JP2002072771A - Image forming apparatus, color image forming apparatus, and image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which obtains the high posi tional precision of the top and reverse surfaces of transfer paper even if the transfer paper shrinks before and after fixation. SOLUTION: This electrophotographic image forming apparatus mounted with a variable magnification and nonstick ADU is equipped with a scale factor correction control means which detects the size of a sheet before and after heat fixation and calculates an expansion/contraction ratio from the detection results, and determines the magnification of a toner image to be transferred to the transfer paper send in a toner image forming means again by an inverting conveyance means according to the expansion/contraction ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for thermally fixing toner images on both sides of a transfer sheet by using an electrophotographic method.

[0002] The present invention also relates to a color image forming apparatus for forming a color image on transfer paper using an electrophotographic method.

[0003] The present invention also relates to an image reading apparatus that changes a scanning magnification by changing a scanning speed of the image reading apparatus.

[0004]

2. Description of the Related Art (1) In an image forming apparatus using an electrophotographic method, a technique (heating and fixing method) of fixing an unfixed toner image transferred onto a transfer sheet by heating, melting and fixing the image is known. . As the heat fixing method, a sheet heater method, an infrared lamp method, and a fixing roller method which is currently most widely used are known.

In an image forming apparatus that fixes a toner image by using a heat fixing method, since the moisture contained in the transfer paper evaporates due to heat, the transfer paper shrinks after fixing. The shrinkage ratio (shrinkage ratio) differs depending on the type and thickness of the transfer paper. It is empirically known that it takes about 15 to 20 minutes for the transfer paper, which has shrunk once by heat fixing, to absorb the moisture in the air and return to the original size.

In general, when an image is formed on both sides of a transfer sheet, a toner image is transferred to one side (front side) of the transfer sheet, heated and fixed, and then transferred to the other side (back side) of the transfer sheet. Is transferred and fixed again by heating. Therefore, when the toner image is transferred to the back surface, the transfer paper is transferred while shrinking, and there is a problem that the image sizes of the front surface and the back surface are different.

A technique for solving this problem is disclosed in Japanese Unexamined Patent Publication No.
No. 288560 and JP-A-10-149057.

Japanese Patent Application Laid-Open No. 4-288560 discloses that an optical sensor detects a vertical size and a horizontal size of a transfer sheet at a position immediately upstream of a transfer position on a conveyance path, and then a position immediately downstream of a heat fixing device. A technology is described in which the vertical size and the horizontal size of the transfer paper are detected by the same sensor, the vertical and horizontal expansion / contraction ratios of the transfer paper are calculated, and the scanning speed of the optical system is switched based on the expansion / contraction ratio. .

Japanese Patent Application Laid-Open No. Hei 10-149057 discloses that, in order to reduce the control load of the technology described in Japanese Patent Application Laid-Open No. Hei 4-288560, one sheet is provided by an optical sensor at a position immediately upstream of a transfer position on a transport path. Detects the vertical size of the first transfer paper before and after fixing, calculates the vertical expansion and contraction rate of the first transfer paper, and scans the optical system based on the expansion and contraction rate of the first transfer paper after the second transfer paper. A technique for controlling the speed to be switched is described.

Further, in recent years, digital copying machines have begun to be used for simple publishing (light printing), and the requirements for the positional accuracy of the front and back of a toner image have become strict. When the problem that the image size of the front surface and the back surface is different occurs, there is a problem that the positional accuracy of the images of the front surface and the back surface cannot be obtained.

The techniques described in JP-A-04-288560 and JP-A-10-149057 detect a transfer sheet being transported by an optical sensor, and detect the size of the transfer sheet before and after fixing from the moving time. Therefore, there is a problem that the detection itself has a large error factor. For example, when operating under general control conditions of a conveyance speed of 200 mm / s and a detection interval of the sensor of about 5 ms, 200 mm / s
Since s × 5 ms = 1 mm, it has a detection error of 1 millimeter, and cannot meet recent severe requirements at all. Further, since the behavior of the transfer paper on the transport path is unstable, there is a problem that the detection of the sensor itself has a variation of about 0.5 mm.

(2) In a color image forming apparatus utilizing an electrophotographic system, it has been conventionally determined whether a document is a color document or a monochrome document, and a color image is formed only when the document is determined to be a color document. An ACS method for performing a copying process has been proposed (ACS: Auto color).
Selector). It is known that the adoption of the ACS method makes it possible to prevent a reduction in copying speed and to stop an image forming system for colors irrelevant to image formation to prevent deterioration (scattering, waste) of materials (eg, developer).

There is also a strong demand for high quality color copying. It is well known that faithful reproducibility of a highlight portion (low-density portion) is a major factor affecting the image quality of a color image, and an electrophotographic color image forming apparatus is no exception. For this reason, the reading performance of the scanner unit is remarkably improved and stable, and the color difference of 3.5 is obtained.
In order to suppress the following, a level of about 0.03 is reproduced in reflection density.

However, even if a color image forming apparatus provided with such a scanner unit determines whether a color original or a monochrome original by the ACS system and forms a color image in accordance with the result of the determination, the following problem occurs. Would.

In recent years, paper recycling has progressed. For example, some recycled paper has a yellowish background, and the use of such recycled paper as a color background document has increased. And
It is not uncommon for color copying to be performed using a color background document having specific color information and a reflection density of about 0.1. When such recycled paper is used as a color background document, the background level is reproduced as a fog image in the output image, and specifically, the output in a state where the yellow toner is thinly fixed in the highlight portion. May be obtained. Such an output image is different from the image imagined by the user, and the user may determine that the reproducibility of the color image is rather low.

When a monochrome image is formed, the reproduction of such a fog image can be prevented by not reproducing the reflection density of about 0.2 or less. And the need to improve the reproducibility of color information, if the reproduction level of the reflection density is determined uniformly, copying with a color document having specific color information on the background and a certain reflection density However, there is a problem that it is difficult to prevent the reproduction of the fog image while satisfying the faithful reproducibility of the highlight portion.

In addition, color materials unrelated to image formation deteriorate,
There is a problem of being wasted. In the color image forming apparatus, better output can be obtained by using transfer paper having a certain degree of smoothness, such as coated paper that has been subjected to special processing. However, there is a problem that coated paper is expensive and cannot be used without restriction. To solve this problem, a paper cassette with coated paper and a paper cassette with plain paper are attached to the color image forming apparatus. There is a problem in that the operability of selecting a cassette is complicated.

(3) In many cases, a copying machine is provided with a scaling function for changing the magnification of an image information and an output image of a document, and the image reading device provided in the copying machine changes the scanning speed to provide the scaling function. There are examples to be realized. The change of the scanning speed is realized by changing the number of rotations of the drive motor for driving the optical lamp, the main reflecting mirror, and the optical mirror group.

In recent years, the range of magnification has expanded, for example, 50
Copiers have been introduced in which a user can arbitrarily select a magnification in a range from about% to 400%. Here, 50% magnification means obtaining an output image reduced to 1/2 scale (area ratio 1/4) with respect to the original, and 400% magnification is 4 times (16 times area ratio) with respect to the original. Obtaining an enlarged output image.

In this case, referring to an LUT or the like registered in advance, the rotational speed corresponding to the set magnification is reduced so that the scanning speed is decreased as the magnification is increased, while the scanning speed is increased as the magnification is decreased. The rotation speed after the change is determined.

In order to cover the magnification range of 50% to 400% by controlling the rotation speed of the drive motor, it is necessary to use a rotation range in which the maximum rotation speed is eight times the minimum rotation speed of the drive motor. . Generally, the torque of the motor decreases as the number of rotations increases, and it is necessary to use a motor that can generate a large torque in the high rotation range, considering that the load of the optical lamp, main reflecting mirror, and optical mirror group to be driven is constant. There is. For example, if the torque value t1 is required at the rotation speed r1, the motor A
Is not adopted and the motor B is adopted.

However, the motor is generally large and expensive if it can generate a large torque in a high rotation range, and the use of such a motor causes a problem that the cost of the copying machine increases.

Also, a motor operating in a wide rotation range does not always operate stably in the entire range. For example, the motor may become an unnecessary vibration source, or may become unstable in a low rotation range, causing uneven rotation. In a copier, there is a problem that image defects such as line fluctuation may occur due to such rotation unevenness and vibration.

[0024]

(1) The present invention solves the problem that high-precision size detection cannot be performed by the conventional technology for detecting the size of the transfer paper before and after fixing from the moving time.
It is an object of the present invention to provide an image forming apparatus capable of obtaining positional accuracy of a front surface and a back surface with high accuracy even if transfer paper contracts before and after fixing.

(2) It is an object of the present invention to provide a color image forming apparatus which prevents a fog image from being reproduced even when a color background document such as recycled paper is copied in color.

Another object of the present invention is to provide a color image forming apparatus for selecting a transfer sheet suitable for forming a color image when a document has color information.

(3) An object of the present invention is to realize a low-cost image reading apparatus in which a small and inexpensive motor is operated stably and image defects are less likely to occur.

It is another object of the present invention to realize a low-cost image forming apparatus capable of stably operating a small and inexpensive motor to read an image in which image defects are less likely to occur.

[0029]

Means for Solving the Problems (1) The object of the present invention can be solved by the image forming apparatus according to the first aspect. In other words, the image forming apparatus according to claim 1 is an image reading unit that optically scans a sheet placed on a platen and converts an electric signal converted by a photoelectric conversion element into digitized image data. Magnification changing means for changing the magnification of the toner image formed based on the image data; toner image forming means for transferring the toner image formed based on the magnification to transfer paper; A heat-fixing unit for heat-fixing, and a reversal conveyance unit for reversing the sheet while holding the transfer sheet on which the toner image is heat-fixed on one side and feeding the toner image to the toner image forming unit again, and heat-fixing the toner image on both sides of the transfer sheet An image forming apparatus for detecting the size of a sheet before heating and fixing placed on the platen based on the image data converted by the image reading means. Size detecting means, second size detecting means for detecting the size of the sheet after heating and fixing placed on the platen based on the image data converted by the image reading means, the size of the sheet before heat fixing and heat fixing An expansion / contraction ratio calculating unit that calculates an expansion / contraction ratio from a size of a sheet afterward, and determines the magnification of the toner image to be transferred to the transfer paper sent again to the toner image forming unit by the reverse conveyance unit based on the expansion / contraction ratio. And a magnification correction control unit.

According to this image forming apparatus, even if the transfer paper shrinks before and after fixing, the positional accuracy between the front and back surfaces can be obtained with high accuracy.

(2) The object of the present invention can be solved by the color image forming apparatus according to the ninth aspect. That is, claim 9
A color image forming apparatus that includes: an image reading unit that reads color image information from a document; and a color image forming unit that outputs a color image according to image forming conditions based on the read color image information. A separating unit that separates the background color information and density information of the document from the color image information, and a control unit that changes the image forming condition according to the background color information and density information of the separated document. It is characterized by having.

According to this color image forming apparatus, it is possible to prevent the fog image from being reproduced even when performing color copying of a color background document such as recycled paper.

The object of the present invention can be solved by a color image forming apparatus according to the present invention. That is, the color image forming apparatus according to claim 16 is based on an image reading unit that reads color image information and monochrome image information from a document, a plurality of paper feed trays, and the read color image information.
A color image forming apparatus comprising: an image forming unit that outputs a color image to transfer paper fed from a paper feed tray;
Separation means for separating the background color information of the document from the color image information, classification means for classifying the document based on the separated background color information, and classification of the transfer paper stored in each of the plurality of paper feed trays. Means for assigning an attribute to each paper feed tray, and selecting a paper feed tray to which an attribute matching the classification of the document is added, and feeding the transfer paper from the selected paper feed tray to form an image. Features.

According to this color image forming apparatus, when a document has color information, it is possible to select a transfer sheet suitable for forming a color image.

The object of the present invention can be solved by an image forming apparatus according to the present invention. That is, a color image forming apparatus according to claim 19, comprising: an image reading unit that reads color image information from a document; and an image forming unit that outputs a color image to transfer paper based on the read color image information. In the image forming apparatus, an area determining unit that separates a portion where color density information and color density information are continuous from each other by separating a background area of an original from an image area including image information, Means for determining the occupancy of the background area, and mode selection means for setting image processing conditions for inhibiting the reproduction of the background area of the document, and prohibiting the reproduction of the original background area according to the occupancy. Features.

According to this color image forming apparatus, the reproduction of the fogged image can be prevented even when copying with a color original such as recycled paper.

(3) The object of the present invention can be solved by an image reading apparatus according to the present invention. That is, an image reading apparatus according to claim 20, wherein the drive motor as a drive source is an image reading apparatus that scans an optical lamp, a main reflecting mirror, and an optical mirror group in a sub-scanning direction and reads image information from a document on a platen. And a transmission means for transmitting a drive to change the scanning speed of the optical lamp, the main reflecting mirror, and the optical mirror group.

According to this image reading apparatus, a small and inexpensive motor can be operated stably, and an image reading apparatus in which image defects hardly occur and which is low in cost can be realized.

The object of the present invention can be solved by an image reading device according to claim 26. That is, the image forming apparatus according to claim 26 is an image reading device that scans an optical lamp, a main reflecting mirror, and an optical mirror group in a sub-scanning direction to read image information from a document on a platen; An image forming apparatus comprising: an image forming unit that forms an image based on an electrophotographic method based on a driving motor as a driving source of the image reading unit; and a group of optical mirrors, a main reflecting mirror, and an optical mirror that transmit driving. Characterized by having a speed changing means for changing the scanning speed.

According to this image forming apparatus, a small and inexpensive motor can be operated stably, and an image forming apparatus in which image defects hardly occur and which is low in cost can be realized.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) An embodiment in which the image forming apparatus of the present invention is applied to a digital electrophotographic copying machine will be described below with reference to the drawings, but the present invention is not limited to this. Not something.

First, an overall configuration and a schematic process of the copying machine will be described with reference to FIG. 1 which is a schematic sectional view of the copying machine.

In the copying machine according to the present embodiment, an automatic document feeder 1 is provided at the top of the copying machine main body, and an image reading device 2, an image forming section 3, a storage section 4, a transport path 5, And a paper discharge / re-feed unit 6.

The automatic document feeder 1 is an example of the platen cover of the present invention, and is provided at an upper portion of a copying machine main body, feeds out documents one by one, and conveys them to an image reading position of the document.
This is a device for discharging a document after image reading. The automatic document feeder 1 includes a document table 11 on which a document is placed, a document separation unit 12 for separating the documents placed on the document table 11 one by one, and transports the documents separated by the document separation unit 12. A document transport unit 13, a document discharge unit 14 for discharging a document transported by the document transport unit 13, a document discharge table 15 for receiving and placing a document discharged by the document discharge unit 14, A document reversing unit 16 for reversing the front and back of the document when reading images on both sides of the document is provided.

A plurality of originals placed on the original placing table 11 are separated by the original separating section 12 and conveyed one by one. The document separated and conveyed by the document separation unit 12 is conveyed by the document conveyance unit 13, and the image of the document is read through the slit 21 by the image reading device 2 provided below. The scanned document is
The document is discharged onto a document discharge table 15 by the document discharge unit 14. By the way, when scanning images on both sides of a document,
The original from which the image on the front side has been read is inverted by the original inverting unit 16, and is again conveyed by the original conveying unit 13.
Through 1, the image on the back side of the document is read. Then, the original from which the image on the back side has been read is sent to the original discharge unit 14.
As a result, the document is discharged onto the document discharge table 15. Such a process is repeated for the number of originals placed on the original placing table 11, and an image of the original is read.

The automatic document feeder 1 is integrally foldable. By raising the automatic document feeder 1 and opening the platen glass 22 which is an example of the platen of the present invention, The document can be placed directly on the platen glass 22. In the present embodiment, the image of the document is read while the document is transported by the document transport unit 13. However, the document transported by the document transport unit 13 is stopped on the platen glass 22. It is also possible to read the image above. Further, it is also possible to raise the automatic document feeder 1 to perform scanning exposure while keeping the platen glass 22 open (hereinafter, also referred to as a sky shot).

The image reading device 2 is an example of the image reading means of the present invention, and is a means for reading an image of a document and obtaining image data, and is provided at an upper portion in the main body of the copying machine.
The image reading apparatus 2 includes a slit 21 which is a slit-shaped opening for reading an image of a document being conveyed by the document conveying unit 13 of the automatic document feeder 1, and a document table for directly placing the document. Platen glass 2
2. A first mirror unit 23 in which a lamp 231 that is a light source for irradiating the original with light and a first mirror 232 that reflects reflected light from the original are integrated, and a second mirror that reflects light from the first mirror 232 241 and third mirror 242
And a slit 21
An imaging lens 2 serving as an imaging unit for imaging reflected light from an original on the platen glass 22 on the CCD 26 to be described later
5, a linear CCD 26 for photoelectrically converting the optical image formed by the imaging lens 25, and an A / D converter 27 for A / D converting an electric signal for each pixel output from the CCD 26 into a digital signal. have. Incidentally, the CCD 26 is an example of the photoelectric conversion element of the present invention.

When reading the original fed by the automatic original feeder 1 with the image reading device 2, the first mirror unit 23 and the V mirror unit 24 are connected to the first mirror unit 23 as shown in FIG. It is located below the slit 21. The lamp 231 irradiates the original conveyed on the slit 21 by the original conveyer 13 with light, and the light reflected from the original passes through the first mirror 232 and the second mirror 232.
The light enters the CCD 26 via the mirror 241, the third mirror 242, and the imaging lens 25. The CCD 26 photoelectrically converts the incident light to read the image of the original in the main scanning direction (the direction perpendicular to the paper surface in FIG. 1). On the other hand, since the original is moved in the sub-scanning direction by the original transport unit 13, The entire image can be read. The A / D-converted image data is appropriately subjected to image processing and supplied to a laser writing system 33 which is an exposure unit described later.

When an original is directly placed on the platen glass 22, the first mirror unit 23 and the V mirror unit 24 are moved along the platen glass 22 to the right in FIG. An image on a document can be read. Hereinafter, the operation of operating each unit of the image reading device 2 to scan the original or the transfer paper placed on the platen glass 22 and output the corresponding digital signal is also referred to as a scanning operation.

When detecting the size of the transfer sheet before and after the heat fixing, the transfer sheet is placed on the platen glass 2.
2, the first mirror unit 23 and the V mirror unit 24 are placed along the platen glass 22 as shown in FIG.
, The outer edge of the transfer paper is detected while moving to the right.

In the automatic document feeder 1, the surface in contact with the platen glass 22 is made of a white member so that there is no difference between the light reflected on the white background of the document and the light reflected on the automatic document feeder 1. It is. On the other hand, if reading is performed with the automatic document feeder 1 opened, there is a case where disturbance light enters the CCD 26 from the platen glass 22 and a case where disturbance light is blocked by the document and does not enter the CCD 26. It is possible to accurately detect the outer edge of a document or transfer paper placed on the sheet 22.

The image forming section 3 is an example of the toner image forming means of the present invention, and forms a toner image on the photosensitive drum 31 in accordance with the image data obtained by the image reading device 2, and forms the formed toner image. Is transferred onto a transfer sheet which is a sheet-like recording material. The image forming unit 3 of the present embodiment forms an image using an electrophotographic process. The image forming unit 3 has a photoconductive drum 31 (photoconductor) having a photoconductive photosensitive layer and carrying a toner image, a charger 32 (charging unit) for uniformly charging the photoconductor drum 31, and reading by a CCD 26. A laser writing system 33 (exposure unit) for exposing the photosensitive drum 31 to form a latent image based on image data, and a developing unit 34 for developing the latent image on the photosensitive drum 31 to form a toner image (Developing unit), a transfer unit 35 (transfer unit) that transfers the toner image formed on the photosensitive drum 31 onto transfer paper conveyed at a preset process speed Vp, and a transfer where the toner image is transferred. Paper to photosensitive drum 31
A separator 36 for separating the toner from above, a cleaning unit 3 for removing the toner remaining on the photosensitive drum 31 after the transfer
7. Then, around the photosensitive drum 31,
Charging device 32, laser writing system 33, developing device 34, transfer device 3
5, a separator 36 and a cleaning unit 37 are arranged.

The heat fixing section 38 is an example of the heat fixing means of the present invention, and heat-fixes the toner image transferred to the transfer paper by the image forming section 3.

The photosensitive drum 31 is rotated in the direction of the arrow by a drive unit (not shown), and is uniformly charged by the charger 32. The photosensitive drum 31 is exposed in synchronism with the leading end of the transfer paper conveyed from a registration roller 56 described later. The started latent image formation by the laser writing system 33 and development by the developing device 34 are performed, and a toner image based on the image data read by the CCD 26 is formed. The formed toner image is transferred by the transfer unit 35 onto transfer paper that is separately conveyed. The transfer paper on which the toner image has been transferred is separated from the photosensitive drum 31 by the separator 36 and
Then, the toner image is heated and fixed on the transfer paper by a heating and pressing action. On the other hand, the photosensitive drum 31 on which the toner image has been transferred to the transfer paper continues to rotate further,
The toner remaining on the photosensitive drum 31 is removed by the cleaning unit 37, and is used for the next image formation.

In the present embodiment, the photosensitive drum 31
In the vicinity of the photoconductor drum 31 between the photoconductor drum 31 and the registration roller 56, a pre-drum conveyance roller 39 for conveying the transfer paper sent out from the registration roller 56 is provided. I have. Also, the separator 36
In order to transport the transfer paper separated by the separator 36 between the and the heating and fixing unit 38, a transport roller (unsigned) and a belt (unsigned) for supporting and transporting the back side of the transfer paper are provided. Provided.

The storage section 4 is a storage section for storing a plurality of transfer papers in a stacked state. In the present embodiment, a plurality of storage units 4, that is, a first storage unit 4A, a second storage unit 4B, and a third storage unit 4C are provided, and these storage units 4A to 4C are
It is arranged below the image forming unit 3 in multiple stages. As the recording material stored in these storage sections 4A to 4C, there are various media such as OHT in addition to transfer paper such as plain paper and recycled paper.

The transport path 5 is a part of a transport section for transporting the recording material from the storage section 4 to the image forming section 3 and includes a storage section 4A.
4C is configured to be able to be conveyed to the image forming unit 3. The specific configuration and operation of the transport path 5 will be described later in detail.

The paper discharging / re-feeding unit 6 is an example of the reversing conveyance means of the present invention, and reverses the transfer paper on which the image is formed by the image forming unit 3 on the transfer paper conveyed by the conveyance path 5. Means for re-feeding or discharging the photosensitive drum 31. The paper discharge / re-feed unit 6 discharges the transfer paper on which the toner image is heated and fixed from the heat fixing unit 38, and discharges the transfer paper discharged by the fixing discharge roller 61 to the outside of the apparatus as it is. A switching unit 62 for switching the transport path between a case where the sheet is inverted and then discharged or a case where the sheet is re-fed for forming an image on the back, a discharge roller 63 for discharging the transfer sheet outside the machine, A paper discharge tray 64 provided on the side surface for stacking the transfer paper discharged by the paper discharge roller 63, a reversing unit 65 for reversing the front and back of the re-transferred transfer paper, and a transfer paper reversed by the reversing unit 65. A re-feed unit 66 for re-feeding the image to the image forming unit 3 is provided.

The transfer path for transferring the transfer sheet from the storage section 4 including the transfer path 5 to the photosensitive drum 31 of the image forming section 3 and the transfer sheet from the reversing section 65 including the re-feed section 66 to transfer the transfer sheet to the photosensitive member. Both of the conveyance paths for re-feeding the paper to the drum 31, and
A group of rollers for transporting the transfer paper on these transport paths is collectively referred to as a transport unit that transports the recording material to the image forming unit 3.

When the transfer sheet on which an image has been formed by the image forming section 3 is to be discharged as it is, that is, with the image-formed side facing upward, the switching section 62 is switched to the position shown by the dashed line in FIG. The sheet is discharged to a sheet discharge tray 64 outside the apparatus by a roller 61 and a sheet discharge roller 63. When the transfer sheet on which an image is formed is turned over and discharged, that is, when the transfer is performed with the image-formed side down, the switching unit 62 is switched to the position shown by the solid line in FIG. The transfer paper conveyed by the rollers 61 is once conveyed in the direction of the reversing unit 65, and after the transfer paper passes through the switching unit 62, the conveyance direction is reversed, and the paper is discharged by the paper discharge rollers 63. Discharge to 64.

On the other hand, when forming an image on the back side of the transfer sheet, the switching section 62 is switched to the position shown by the solid line in FIG. 1 and the transfer sheet conveyed by the fixing discharge roller 61 is conveyed in the direction of the reversing section 65. By performing switchback by the reversing unit 65, the reversing is performed, and the sheet is conveyed to the re-feeding unit 66. When the switchback is performed, the switchback is performed while the transfer paper is held between the pair of reverse conveyance rollers 67. Further, in order to prevent the transfer paper being switched back and the subsequent transfer paper from colliding with each other with the reversing conveyance roller pair 67, the transfer paper that has been subjected to the switchback is immediately processed at the process speed Vp by the re-feeding unit 66. The sheet is fed again to the image forming unit 3. Since the process speed Vp is set in advance according to the size of the transfer sheet, the time required for re-feeding, which is determined by the path length of the transport unit and the process speed Vp, is substantially constant for transfer sheets of the same size. Therefore, when compared with a re-feeding unit that picks up the transfer papers once accumulated in the stacker and re-feeds them to the image forming unit 3, all the transfer papers are re-supplied in a very short time. .

In the present embodiment, the platen glass 22 has been described as an example of the platen of the present invention. However, if the image reading means optically scans the sheet, it can be fixed without blocking the sheet. The platen may use any shape and material. Although the automatic document feeder 1 has been described as an example of the platen cover of the present invention,
It is sufficient that the image reading unit optically scans the sheet so as to prevent intrusion of disturbance light.

Next, the operation of the copying machine will be described with reference to FIG. 2 which is a functional block diagram of the copying machine. The copying machine according to the present embodiment switches between two operation modes, a normal mode and a front / back magnification adjustment mode, according to a user's specification, and executes the operation mode. In the normal mode, the copying machine obtains image data from a document placed on the platen glass 22 by the image reading device 2 and executes a copying operation. In the front / back magnification adjustment mode, the image reading device 2 measures the size of the transfer paper before and after heating and fixing, calculates the expansion / contraction ratio, and executes a series of operations up to setting the magnification to be used for backside copying. I do. The original and the transfer paper are each an example of the sheet of the present invention, and the transfer paper is used as a sheet when size detection is performed, and the original is used as a sheet when copying is performed.

The setting / operation unit 100 is provided with a touch panel for displaying necessary information to the user and displaying various buttons by software for giving an instruction to the copying machine. The setting / operation unit 100 includes a normal mode setting button group 101, a mode shift button 102, a transfer paper size setting button 103, a transfer paper quality setting button 104, and a display unit 105.

A normal mode setting button group 101 is used for inputting an instruction necessary for a normal operation of the copying machine, such as selection of a transfer sheet, setting of the number of copies, setting of a copy magnification, selection of a duplex mode, setting of post-processing, cancellation, and the like. It consists of various buttons.

The mode transition button 102 is an example of a mode switching means of the present invention, and is an operation button for switching from the normal mode to the front / back magnification adjustment mode, and is displayed on the setting / operation section 100 while the copying machine is on standby. When the user operates the mode shift button 102, the copier switches from the normal mode to the front / back magnification adjustment mode, and the setting / operation unit 100 displays a transfer paper size setting button 103, a transfer paper quality setting button 104, and a display unit 105. Then, the user's instruction can be input.

The transfer paper size setting button 103 is an example of the size input means of the present invention, and the user specifies the size of the transfer paper placed on the platen glass 22 for size detection in the control program of the copying machine. This is a setting button for giving information. The transfer paper stored in the storage units 4A to 4C can be selected.

The transfer paper quality setting button 104 is an example of the type input unit of the present invention. The user specifies the paper quality of the transfer paper placed on the platen glass 22 for size detection in the control program of the copying machine. This is a setting button for giving information. For example, the paper thickness is selected in the categories of plain paper, thick paper, thin paper, and the like.

Here, the term "paper quality" focuses on the shrinkage after heating and fixing among various characteristics determined by the material and thickness of the paper. Even if the transfer paper has the same paper quality, the shrinkage after passing through the heating and fixing unit 38 at the process speed Vp differs even if the transfer paper has the same size, and it also absorbs moisture in the air and returns to the same size as before the heating and fixing. The required time is also different. Further, since the characteristics of the heating and fixing unit 38 and the process speed Vp are different for each type of copying machine, the shrinkage ratio before and after the heating and fixing differs for each type of copying machine even if transfer paper of the same size and the same paper quality is used. .

The display unit 105 is an example of a warning unit according to the present invention, and is assigned to a part of the above-mentioned touch panel, and displays a warning regarding an error generated during operation in the front / back magnification adjustment mode. For example, in the front / back magnification adjustment mode,
The shrinkage ratio is calculated by actually measuring the size of the transfer paper before and after the heat fixing, and a warning is displayed when the measurement is invalidated as described later.

The normal mode setting button group 101, the mode shift button 102, the transfer paper size setting button 103, and the transfer paper quality setting button 10 included in the setting / operation unit 100 are provided.
Reference numeral 4 may be a mechanical push-type button or a slide switch, and the display unit 105 may be configured to warn by flashing a lamp or voice in addition to displaying a character.

The detection operation start button 106 is a mechanical push button which is a part of the setting / operation unit 100 but is separately provided from the touch panel. When the user operates the detection operation start button 106, the copier is set on the platen glass. 22
The reading operation of the transfer paper placed on the printer is started. The detection operation start button 106 may also be used so as to operate as a copy start button in the normal mode.

The image reading device 2 includes the above-described platen glass 22, CCD 26, and A / D converter 27.
A scan control unit 28 that adjusts the operation of each unit of the image reading device 2 when the magnification is changed in the normal mode is provided.

A / D converter 27 provided in image reading device 2
Is output to the image processing unit 110 after being subjected to shading correction and the like, and processed.

The image processing section 110 includes a selector 111, a transfer paper / sky shot discriminating section 121, a sub-scanning direction white line counting section 122, an expansion / contraction ratio calculation section 123, an expansion / contraction ratio storage section 124, a copy processing section 131, and a memory system. Processing unit 13
2. It has a writing system processing unit 133. The transfer paper / sky shot discriminating unit 121, the sub-scanning direction white line counting unit 122, the expansion / contraction ratio calculation unit 123, and the expansion / contraction ratio storage unit 1
Reference numeral 24 denotes a block belonging to the front / back magnification adjustment system A and used in the front / back magnification adjustment mode. The copy processing unit 131, the memory processing unit 132, and the writing processing unit 133 belong to the normal processing system B and are blocks used in the normal mode.

The selector 111 converts the image data output from the image reading device 2 into a front / back magnification adjusting system A and a normal processing system B.
This is a selection means for selecting which of the two is to be passed. The selector 111 selects a state in which the image data is transferred to the normal processing system B when the copier is powered on, and selects a state in which the image data is transferred to the front / back magnification adjusting system A when the user operates the mode shift button 102. Is done. When the front / back magnification adjustment mode ends, the selector 1
11, the state in which the image data is automatically transferred to the normal processing system B can be selected.

The transfer paper / sky shot discriminating section 121
Whether the light incident on the CD 26 is reflected light from the size measurement transfer paper P1 or disturbance light (sky shot) is determined based on the intensity of the incident light. In the front / back magnification adjustment mode, the automatic document feeder 1 is raised to raise the platen glass 22.
Since the scanning exposure is performed with the top open, the reflected light reflected by the transfer paper and incident on the CCD 26 is almost the same as the reflection from the white portion of the document, and is blocked from the platen glass 22 by the transfer paper P1 for size measurement. However, since the disturbance light incident on the CCD 26 is almost the same as the reflection from the black portion or the gray portion of the document, it is possible to determine these.
The transfer paper / sky shot determination unit 121 converts the image data of the pixel corresponding to the reflection from the transfer paper P1 for size measurement into white, and the image data of the pixel corresponding to the sky shot into black and white binary digital data in which the image data is replaced with black. Output.

The white line counting section 122 in the sub-scanning direction
Based on the digital data output from the transfer paper / sky shot determining unit 121, each line is determined as a white line or a black line, and the number of white lines in the sub-scanning direction is counted. In the determination of the white line or the black line, each line data is determined as a white line or a black line based on the number of white pixels and the number of black pixels included in each line. As a reference value for determination, a threshold hold value is set as a preset value, and is loaded as a reference value of a control program.

The sub-scanning white line counting section 122 outputs a count value Hn corresponding to the number of white lines. Since the number of white lines is directly proportional to the size of the transfer paper in the sub-scanning direction, if the count value Hn is obtained, it means that the transfer paper size has been detected.

In this embodiment, an example in which only the size in the sub-scanning direction is detected will be described. Of course, the size in the main scanning direction may be detected by counting the number of white pixels in each line. If the size detection in the direction and the sub-scanning direction is performed, the detection becomes more accurate.

In the front / back magnification adjustment mode, the image reading device 2
Is processed by the transfer paper / sky shot discriminating unit 121 and the sub-scanning white line counting unit 122 to detect the size of the transfer paper. Such a detecting operation is performed once before and after the heat fixing, and the operation of placing the transfer paper after the heat fixing on the platen glass 22 is performed by the heat-fixed transfer paper discharged to the paper discharge tray 64. The paper is manually executed by the user.

The expansion / contraction ratio calculating section 123 is an example of the expansion / contraction ratio calculating means of the present invention, and calculates the expansion / contraction ratio based on the detected size of the transfer paper before and after the heat fixing. In this embodiment, the expansion / contraction ratio is determined based on the size of the transfer paper before heat fixing, and the ratio between the transfer paper size after heat fixing and the transfer paper size before heat fixing is used as the expansion / contraction ratio.

The expansion / contraction ratio storage unit 124 is an example of the expansion / contraction ratio storage unit of the present invention, and stores the expansion / contraction ratio calculated by the expansion / contraction ratio calculation unit 123, and stores the expansion / contraction ratio according to the size of the detected transfer paper. It is also possible to use a rewritable semiconductor memory or the like for storing the size of the transfer paper available in the copier and the corresponding paper quality.

Next, the normal processing system B will be briefly described. The processing executed in the normal processing system B is a well-known technique in the field of digital copiers, and thus description of individual processing is omitted.

The copy processing section 131 performs an area determination process,
Brightness / density conversion processing, spatial filter processing, scaling processing, γ
Conversion processing and the like are sequentially executed. The magnification changing unit 131a that executes the scaling processing is an example of a magnification changing unit of the present invention,
The magnification of a toner image formed based on image data is changed. The memory processing unit 132 sequentially executes an error diffusion process, a tilt correction process, a density correction process, and the like. The write processing unit 133 executes a write start position synchronization process, LD control, and the like. The image data output from the image reading device 2 is sequentially subjected to these processes in the normal processing system B, and is converted into a laser drive signal. The laser drive signal is a signal for determining the timing of turning on and off the laser light emitting element included in the writing exposure unit 140.

The write exposure unit 140 executes laser modulation, synchronization control, and polygon motor control. The laser modulation is performed based on the laser drive signal, whereby a latent image corresponding to the image of the document is formed on the surface of the photosensitive drum 31. Synchronous control is control of the timing of starting writing on the photosensitive drum 31 so that each image data to be formed on both sides of the transfer paper is not shifted.

The image forming system control section 150 includes the charging device 32 and the developing device 3 among the aforementioned members constituting the image forming portion 3.
4. The operations of the transfer unit 35, the separator 36, and the cleaning unit 37 are controlled. For example, when the process speed Vp is changed in accordance with the size of the transfer paper, the operation timing of these units is adjusted. The image forming system control unit 150 also controls the heat fixing unit 38. Since such control is a well-known technique, the description is omitted.

The transfer paper transport section 160 executes paper feed control, reverse transport control, and post-processing control. Since such control is a well-known technique, the description is omitted.

The engine control section 170 includes a first size detection section 170a, a second size detection section 170b, a magnification correction control section 170c, and a time counter 170d. Size / paper quality control, front / back magnification adjustment mode execution control, fixing control, communication control with the image processing unit, and communication control with the operation / setting unit are executed.

The double-sided image forming process control switches the order of the transfer sheets handled by the sheet discharging / re-feeding unit 6 and the transfer path for re-feeding or discharging in accordance with the number of copies and the presence or absence of double-sided copying. In the case where the control is further performed and the original is copied from a plurality of pages, the output order (page order) of the images formed on the photosensitive drum 31 is controlled.

The transfer paper size / paper quality control controls the operation timing of each section according to the size and paper quality of the transfer paper selected by the user.

In the fixing control, the control relating to the temperature management of the heat fixing unit 38 is executed so as to enable stable heat fixing and reduce energy loss.

Communication control with the image processing unit 110 controls communication of necessary set values and detected values in the normal mode and the front / back magnification adjustment mode. For example, the engine control unit 170 obtains the expansion / contraction ratio S (described later) stored in the expansion / contraction ratio storage unit 124 and executes magnification correction, so that communication of the expansion / contraction ratio S is necessary.

The communication control with the operation / setting unit is for communicating between the setting / operation unit 100 and the engine control unit 170 the contents of the user's input, the operation state of the copying machine, confirmation of the contents of the user's input, and the like. Control.

The front and back magnification adjustment mode execution control includes detecting the size of the transfer sheet before heat fixing (hereinafter also referred to as first size detection) and detecting the size of the transfer sheet after heat fixing (also referred to as second size detection). , Calculation of expansion / contraction ratio, setting of magnification, and the like.

The first size detecting section 170a and the second size detecting section 170b are blocks for executing the first size detection and the second size detection, respectively, in the front / back magnification adjustment mode execution control. When performing the first size detection in the front / back magnification adjustment mode execution control, the first size detection unit 1
70a instructs the front / back magnification adjusting system A to execute size detection, and obtains a white line count value H1 from the sub-scanning white line counting unit 122 as a parameter corresponding to the size of the transfer sheet before heat fixing. When the second size detection is performed, the second size detection unit 170b instructs the front / back magnification adjustment system A to perform the size detection, and sets a sub-size as a parameter corresponding to the size of the transfer sheet after heat fixing. The white line count value H2 is obtained from the scanning direction white line counting unit 122. The details of the front and back magnification adjustment mode execution control will be described with reference to the flowchart of FIG. 4, and the count value H1 and the count value H2 will also be described in detail there.

The reading operation control is for controlling the operation of the image reading apparatus 2. That is, when performing double-sided copying in the normal mode, image formation at the magnification selected by the user is performed for front side image formation, and image formation at the rear side magnification corresponding to the user selection is performed for back side image formation. Perform shaping.

The magnification correction control section 170c is an example of magnification correction control means of the present invention, and is a block for executing magnification correction control. The magnification correction control sets the magnification of the image formed on the back surface with respect to the image formed on the front surface by taking the reciprocal of the expansion / contraction ratio S (described later). When performing double-sided copying, the magnification correction control unit 170c gives the magnification of the toner image to be formed on the back surface of the transfer sheet to the magnification changing unit 131a, and the normal processing system B executes the processing of the image data at the given magnification. I do.

The time counter 170d is an example of the time measuring means of the present invention, and measures a time interval from the first size detection to the second size detection.

Next, referring to the flowchart of FIG. 3 for explaining the execution procedure of the size detection processing executed in the front and back magnification adjustment mode and the flowchart of FIG. 4 for explaining the execution procedure of the front and back magnification adjustment mode, The operation will be described.
The size detection processing is a part of the front / back magnification adjustment mode described with reference to FIG. 4, but will be described before the front / back magnification adjustment mode.

The flowchart of FIG. 3 is a procedure executed by the front / back magnification adjusting system A for image data. In the following description, line data refers to one line of image data that is read in synchronization by each element of the line type CCD 26 among image data constituting one screen of image data.

In the transfer paper / sky shot determining section 121, a threshold hold value serving as a reference for determining whether each line is a white line or a black line is set (S1).
1).

Each line data is input to the transfer paper / sky shot discriminating unit 121 in accordance with the output order of the line type CCD 26. Therefore, based on the threshold hold value, either the white line or the black line is determined for each line. Determine.

When the line data changes from a black line to a white line (S12), the sub-scanning white line counting unit 1
Reference numeral 22 counts the number of white lines sequentially input to obtain a count value. It is determined whether or not the count value thus obtained reaches a preset number N of lines (S13).

The set number of lines N is a margin to be set in order to prevent a size detection failure or the like due to dirt or the like adhering to the transfer paper. If the count value is less than the set number of lines N in the determination in step 13, it is expected that some error has occurred, and thus the white line detected in step 12 is not used for size detection. Therefore, the process returns to the detection of the change from the black line to the white line (S12).

On the other hand, if the count value has reached the set number of lines N, it is not an error, but a white line due to the light reflected from the transfer paper placed on the platen glass 22, and the process proceeds to step S14. The counting of the number of lines is started (S14).

When the line data changes from a white line to a black line (S15), it is determined whether or not the count value obtained by counting the number of sequentially input white lines reaches a preset number M of lines. Is determined (S16).

The set line number M is a margin similar to the set line number N. If the count value is less than the set number M of lines in the determination at step 16, it is expected that some error has occurred. Therefore, the black line detected at step 15 is rejected, and the number of white lines is counted again (S1).
Return to 4).

On the other hand, if the count value is equal to or greater than the set number of lines M, the line is a black line by the sky shot, and the line number counting end process is executed (S17). In the line number counting end process in step 17, first, the counting of the number of white lines being continued from step 14 is stopped, and the obtained white line count value Hn is temporarily stored in a RAM or the like.

In the reading operation of the image reading device 2, the read lines in the main scanning direction are at equal intervals.
The count value Hn obtained in Step 7 corresponds to the size of the transfer paper in the sub-scanning direction.

The set number of lines N and M are N = M. In the copying machine of the present embodiment, the white line up to step 13 is ignored, and the counting of step N14 is started from the (N + 1) th line, while the white line is counted up to the black line of the Mth line. The value Hn is obtained. Here, since N = M, the count value Hn can be directly used as the number of white lines. If N ≠ M, (count value Hn) + (number of set lines N) −
(Set number of lines M) = Hn2 is an accurate number of white lines, which is preferably employed.

In the copying machine of the present embodiment, the size detection processing of steps 11 to 17 is executed for both the transfer paper before heat fixing and the transfer paper after heat fixing.

If the line data starts with white data in step 12, a warning is issued because the user's work may be incomplete and the transfer paper may protrude from the platen glass 22 and be placed. It is desirable.

The above example is an example in which white and black are determined by focusing on each line data. Therefore, the efficiency is improved for the transfer paper whose size is determined by the JIS standard or the like in the A row and the B row. Good size detection processing is possible.

If the size detection is performed by discriminating between white and black for each pixel data, it is possible to accurately detect the size of non-standard transfer paper. In this case, the transfer paper / sky shot determination unit 121 serially outputs the binarized pixel data. Specifically, the line type C
The output is performed in accordance with the arrangement order (main scanning direction) of one line of image data read by the CD 26. When the output of one line of pixel data is completed, the pixel data belonging to the next line is sequentially output.

Then, for the pixel data belonging to each line data, by counting the number of pixels from a change from a black pixel to a white pixel to a change from a white pixel to a black pixel, the image size in the main scanning direction can be accurately detected. It is possible to do.
In the present embodiment, since the image reading device 2 has a resolution of 600 dpi, detection at 43.5 μm is theoretically possible. Note that the resolution of 600 dpi indicates a resolution for reading an original as image data of 600 pixels per inch (about 2.54 cm).

Next, the execution procedure of the front / back magnification adjustment mode will be described with reference to the flowchart of FIG.

When the user operates the mode shift button 102, the copying machine starts the front / back magnification adjustment mode. When the front / back magnification adjustment mode starts, a message indicating that the automatic document feeder 1 should be raised to open the platen glass 22 is displayed on the display unit 105 (S21).

[0119] The engine control unit 170 controls the image processing unit 110
To the image reading device 2 so that the image data is transferred to the front-back magnification adjusting system A, and the selector 111 is switched to such a state (S2).
2).

The setting / operation unit 100 displays a transfer paper size setting button 103 and a transfer paper quality setting button 104,
Since the user is waiting for the input, the user sets the transfer paper size setting button 103 and the transfer paper quality setting button 104.
To set the paper size and paper quality (S23).
The expansion / contraction rate calculated by the following procedure is determined in this step (S23).
It becomes clear that the expansion rate is related to the transfer paper of the paper size and the paper quality specified by. The copying machine is in a standby state in which the size of the transfer paper stored in the storage units 4A to 4C, for example, A3, B4, A4, B5, etc. can be selected by using the transfer paper size setting button 103. By using the transfer paper quality setting button 104, the user stands by in a state where the size of the transfer paper stored in the storage units 4A to 4C, for example, plain paper, thick paper, thin paper, and the like can be selected.

The display unit 105 places the transfer paper before heat fixing on the platen glass 22 and then performs a detection operation start button 1
A guide to operate 06 is displayed (S24). FIG. 4 shows a display example of “Please set the transfer paper before heat fixing on the platen and press the copy button”.
In this embodiment, the copy button also functions as the detection operation start button 106.

When the user operates the detection operation start button 106 (S25), the engine control section 170 issues a scan operation start instruction to the scan control section 28 and an image formation operation start instruction to the image formation system control section 150 based on predetermined conditions. Execute a data processing start instruction to the image processing unit 110 (S2).
6).

When the scan control unit 28 receives a scan operation start instruction in step 26, it controls the operation of each unit of the image reading apparatus 2 and optically removes the transfer paper placed on the platen glass 22 before heating and fixing. Scan to get image data,
This is given to the image processing unit 110. Image data obtained by the image reading device 2 and given to the image processing unit 110 is sent to the front / back magnification adjusting system A by the selector 111.

When the image forming section 3 receives the image forming operation start instruction in step 26, the image forming operation is started based on the instruction from the engine control section 170.

In the present embodiment, for the image forming operation executed in the front / back magnification adjustment mode, transfer of the transfer paper from the storage section 4 is started, and each section is operated without forming a latent image on the photosensitive drum 31. . The transfer paper conveyed by such an operation passes through the heating and fixing unit 38 at the process speed Vp without transferring the toner image, and is discharged to the discharge tray 64.
In the normal image forming operation, the process speed is changed according to the paper size and quality of the transfer sheet. To match the process speed, the process speed Vp used in the image forming operation executed in the front / back magnification adjustment mode is set at step 23. Is changed according to the paper size and paper quality set by the user.
It goes without saying that the transfer paper discharged to the paper discharge tray 64 is contracted in the same manner as the transfer paper subjected to the normal heat fixing process.

When receiving the data processing start instruction (S26), the image processing section 110 starts the size detection processing (S27) for the received image data. When the image processing unit 110 receives the data processing start instruction in step 26, the selector 111 is in a state of sending the image data to the front / back magnification adjustment system A. This is a size detection process.

The size detection processing performed in step 27 is the size detection of the transfer paper before heat fixing (hereinafter also referred to as first size detection processing), and the front / back magnification adjustment system A is used by the first size detection means of the present invention. This is an operation example that operates as an example.

When the first size detection processing and the image forming operation started in step 26 are completed (S28), the time counter 170d provided in the engine control unit 170 operates as an example of the time measuring means of the present invention, and immediately counts the time. Is started (S29). Prior to the start of the time count, the count value Tn is reset.

The display section 105 displays a guide to the effect that the detection operation start button 106 should be operated after the transfer paper discharged to the paper discharge tray 64 is placed on the platen glass 22.

When the user operates the detection operation start button 106 (S30), the engine control section 170 issues a scan operation start instruction to the scan control section 28 and a predetermined condition to the imaging system control section 150 as in step 26. The image forming operation start instruction and the data processing start instruction to the image processing unit 110 are executed (S31).

Upon receiving the data processing start instruction (S31), the image processing section 110 starts size detection processing (S32) for the received image data. When the image processing unit 110 receives the data processing start instruction in step 32, the selector 111 is in a state of sending the image data to the front / back magnification adjustment system A. This is a size detection process.

The size detection processing performed in step 32 is the size detection of the transfer paper after heat fixing (hereinafter also referred to as a second size detection processing), and the front / back magnification adjustment system A is used by the second size detection means of the present invention. This is an operation example that operates as an example.

When the second size detection processing and the image forming operation started in step 31 are completed (S33), the engine control section 170 ends the time count, and the count value Tn is determined (S34).

When the count value Tn is determined, it is determined whether or not the count value exceeds a preset count limit value TL.
That is, it is determined whether the count value Tn <the count limit value TL is true or false (S35). If true, the second size detection is enabled and the process proceeds to step 36. If false, the second size detection is invalidated and a warning is issued again. Display (S38),
Return to step 24. In the present embodiment, control is performed such that engine control section 170 invalidates the second size detection. That is, the engine control unit 170 is an example of the invalidation unit of the present invention.

The count limit value TL is set in advance and stored in a ROM (not shown) or the like, and is loaded by a control program of the copying machine. The count limit value TL is a value corresponding to a time width from when the transfer paper once passes through the heating and fixing unit 38 to when an image is formed on the back surface again when an image is formed on the back surface.

If the count limit value TL is set in this manner, the transfer paper contracted through the heat fixing unit 38 is left between the first size detection and the second size detection, and the second size detection is performed. It is possible to avoid the problem that the size is returned by absorbing moisture before the start and the calculation of the shrinkage ratio becomes inaccurate.

As described above, in step 35, the count value T
If it is determined that n is less than the count limit value TL (that is, true), the expansion / contraction ratio calculation unit 123 executes the calculation of the expansion / contraction ratio, and stores the calculation result in the expansion / contraction ratio storage unit 124 (S
36). The expansion ratio is obtained by calculating the expression of expansion ratio S = count value H2 / count value H1. In the expression, H1 is the count value Hn (corresponding to the transfer paper size before heat fixing) obtained by the size detection in step 27, and the count value H
2 is the count value Hn obtained in the step 32 size detection
(Corresponding to the transfer paper size after heat fixing).

The expansion / contraction ratio S thus calculated is determined by
The transfer paper that has contracted after passing through 8 reflects the degree of contraction at the time when the transfer paper is conveyed again to the image forming unit 3 and an image is formed on the back surface. The magnification of the toner image to be formed is set.

When the calculated expansion / contraction ratio S is stored in the expansion / contraction ratio storage unit 124, it is stored in step 23 in association with the size and quality of the transfer paper designated by the user.

Subsequently, the display unit 105 displays a message for confirming with the user whether or not to execute the detection of the expansion / contraction ratio for transfer paper of another size and / or paper quality (S37). The user who wishes to newly detect the expansion / contraction ratio returns to step 32 and operates the transfer paper size setting button 103 and the transfer paper quality setting button 104 to set the paper size and the paper quality.

If the determination result of step 35 is false (No), the size detection is invalid on the display unit 105,
Displays a warning that size detection should be performed again. That is, when the count value Tn <the count limit value TL, the transfer paper that has expanded and contracted has absorbed moisture and returned to the original size because a longer time has elapsed since the heat fixing process was performed, or Even if the back side image is formed at a magnification set based on the expansion / contraction ratio S, the positional accuracy between the front side and the back side cannot be obtained. Therefore, the procedure following step 24 is executed again.

In the copying machine of this embodiment, the expansion / contraction ratio S is obtained by the procedure described with reference to FIGS. 3 and 4, and is stored in the expansion / contraction ratio storage unit 124 in association with the size and quality of the transfer paper. Then, when performing double-sided image formation, the user is allowed to specify the size and quality of the transfer paper before the start of the job, and refer to the corresponding expansion / contraction ratio S to determine the reciprocal thereof, and perform the back side image formation. Is adopted as the magnification.

Therefore, in the copying machine according to the present embodiment, the size of one transfer paper is affected by the heat fixing process when forming a toner image on the front surface and when forming a toner image on the back surface. Even in the different case, it is possible to form the back surface image by using the magnification reflecting the shrinkage ratio due to the influence of the heat fixing process, and to obtain the position accuracy of the front surface and the back surface with high accuracy.

In the front / back magnification adjustment mode described with reference to FIG. 4, a step for checking whether or not the automatic document feeder 1 has occurred may be provided, or a warning may be displayed only when the automatic document feeder 1 has not occurred.

The expansion ratio S is affected by the environment (temperature and humidity) in which the copying machine operates. Therefore, the expansion / contraction ratio storage unit 12
The expansion / contraction ratio S stored in No. 4 is rewritable without being made permanent. For example, the calculated expansion / contraction ratio Sne
When w is stored in the expansion / contraction ratio storage unit 124 in step 36, the expansion / contraction ratio Sold stored in association with the transfer paper of the same size and paper quality may already be stored. Therefore, in the present embodiment, the previously stored expansion ratio Sold is overwritten by the newly obtained expansion ratio Snew. New expansion ratio Snew and expansion ratio Sold
Is overwritten, a confirmation message to the user may be displayed on the display unit 105. (2) Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

FIG. 5 is a schematic sectional view of a color copying machine as an example of the image forming apparatus of the present invention. The color copying machine of the present embodiment develops a toner image of a different color on each of four sets of photoconductors, and obtains a color toner image by transferring and aligning the developed toner image on an intermediate transfer body. This is a method of transferring this from an intermediate transfer body to transfer paper.

The color copying machine includes an automatic document feeder 401 serving as a document feeder, an image reading unit 402, a color image forming unit 403 for performing an image forming operation, and a feed path 405 and a discharge path 408 which constitute a part of the transfer means. , A paper feed tray 406 as a transfer paper storage unit and a paper discharge tray 40 as a discharge unit
9.

The original is placed on the original feeder table 411 of the automatic original feeder 401 with the image side facing upward, sent out one by one by the operation of the feed roller 412, temporarily stopped by the registration roller 413, and the leading edge is adjusted. Is transported to the transport drum 414,
While the original is being conveyed along the peripheral surface of the
Image reading is performed below 14. Then, the sheet is separated from the transport drum 414 at a position substantially halfway around, and is discharged to a sheet discharge table 415. Although the automatic document feeder 401 has a transfer function for double-sided reading in addition to the transfer function for single-sided reading, this operation is omitted.

In the image reading unit 402, the light source 423
a and a first mirror unit 423 including a mirror 423b
Is stationary at a position directly below the transport drum 414,
A mirror 424 a and a mirror 424 are arranged so as to sequentially illuminate and read the passing documents, and are arranged so as to be orthogonal to the moving direction of the documents
The light is reflected by the second mirror unit 424 including the image b, forms an image on the linear imaging element 426 via the imaging lens 425, and reads color image information and monochrome image information. The image sensor 426 can read a color original by using an image sensor corresponding to, for example, R, G, and B primary colors, or by using an image sensor having a mosaic color filter. The document thus read is discharged to the paper discharge tray 415. On the other hand, the image reading unit 4
The image information of the document image read in 02 is temporarily stored in an image memory (not shown).

Next, the color image forming section 403 will be described. In FIG. 5, four image forming units 430Y,
M, C, K are charging, exposure,
Each of the development and cleaning processes and the primary transfer are performed, and each image forming unit forms one color toner image from four color (single color) toner images of yellow, cyan, magenta, and black. In addition, Y, M, C, and K indicate yellow image, magenta image, cyan image, and black image, respectively. May be attached.

The formation of a yellow toner image by the image forming unit 430Y will be described. Reference numeral 431Y denotes a drum-shaped photoconductor, which is formed by applying an OPC photoconductor (organic photoconductor) on a drum base, is grounded, and rotates clockwise in the drawing. Reference numeral 432Y denotes a scorotron charger (hereinafter, referred to as a charger) which applies uniform high-potential charging to the peripheral surface of the photosensitive drum 431Y by corona discharge. Prior to charging by the charger 432Y, the photosensitive drum 431
In order to eliminate the history of Y, exposure is performed by a static eliminator (PCL) (not shown) using a light emitting diode or the like to eliminate the charge on the peripheral surface of the photosensitive drum 431Y.

After uniform charging of the photosensitive drum 431Y,
The image information stored in the above-described image memory is read, and image exposure based on the image information is performed by the image writing unit 433Y, and an electrostatic latent image is formed on the surface of the photosensitive drum 431Y. (Latent image forming step). Image writing unit 433Y
Is deflected by a rotating polygon mirror 434Y, and corrected by an fθ lens and a cylindrical lens (not shown).
1Y, the main scanning is performed, and the photosensitive drum 431Y
The sub-scan is performed by the rotation of, and an electrostatic latent image is formed. A laser beam scanning optical device using a laser diode is used. As a light source for image exposure, a light emitting element such as a light emitting diode can be used.

At the periphery of the photosensitive drum 431Y, there is provided a developing device 435Y containing a two-component developer composed of a yellow (Y) toner and a carrier (developing means). Each of the developing sleeves 436Y has a built-in magnet, and is configured to rotate while holding the developer.
The gap between the developing sleeve 436Y for each color and the photosensitive drum 431Y in the developing area is larger than the developer layer thickness.
5 mm to 1.0 mm, during which a developing bias in which an AC voltage and a DC voltage are superimposed is applied. The DC voltage has the same polarity as the electrostatic latent image, and reversal development is performed. With the above configuration and operation, the image forming unit 430Y forms a yellow toner image on the surface of the photosensitive drum 431Y.

The image forming units 430M, 430K, and 430K are different from the image forming unit 430Y except that the colors of the toners to be shared are different.
With the same configuration and operation as above, cyan, magenta and black toner images are respectively formed on the photosensitive drums 43.
1Y, M, C, and K are formed on the peripheral surface.

The intermediate transfer belt 470 includes the driving roller 4
While being stretched between the driven roller 71 and the driven rollers 472 and 473 and stretched in a tensioned state by the action of the tension roller 474, while locally abutting against a backup member (not shown) provided on the inner peripheral surface, as indicated by an arrow in the drawing. Rotate as shown. The backup member is in contact with the back surface of the intermediate transfer belt 470, and the intermediate transfer belt 470 and the photosensitive drum 431
The relative positional relationship between Y, M, C, and K is regulated, and the regulation stabilizes the transfer area formed between the photosensitive drums 431Y, M, C, and K and the intermediate transfer belt 470.

The transfer rollers 437Y, M, C, and K apply a transfer voltage for transferring (primary transfer) the toner images formed on the surfaces of the photosensitive drums 431Y, M, C, and K to the intermediate transfer belt 470. It is a means for applying. Transfer roller 43
7Y, M, C and K are photosensitive drums 431Y, M, C and K
And the intermediate transfer belt 470.

The photosensitive drums 431Y, M, C, K, and the intermediate transfer belt 470 are driven at a predetermined process speed Vp.
When the toner image on the peripheral surface of the photosensitive drum 431 approaches the intermediate transfer belt 470 according to the rotation, the toner image on the peripheral surface of the intermediate transfer belt 470 is controlled by the transfer voltage. Transferred to the surface.

In each of the image forming units 430Y, M, C, and K, the start timing of image exposure is controlled so that the toner image of each color after the primary transfer does not shift on the surface of the intermediate transfer belt 470. Is executed.

That is, first, the first color yellow image forming process is started, and the uniform charging by the charger 432Y and the exposure by the image writing section 433Y are performed to form a yellow electrostatic latent image, and the yellow toner is formed. The image is transferred onto the intermediate transfer belt 470 by the action of the transfer roller 437Y (primary transfer)
Is done.

During the development and primary transfer of the first color, the magenta toner image of the second color is formed by the image forming unit 430M through the same process as the formation of the yellow toner image.
The primary transfer is performed on the intermediate transfer belt 470. The timing of starting the exposure of the magenta toner image is determined by the photosensitive drum 431.
The magenta toner image primarily transferred from M to the intermediate transfer belt 470 is controlled so as to overlap the yellow toner image primarily transferred onto the surface of the intermediate transfer belt 470.

For the third color cyan and the fourth color black, the same image formation as that for the second color magenta is performed, and toner images of each color are sequentially superimposed on the peripheral surface of the intermediate transfer belt 470. A full-color toner image is formed on the peripheral surface within one rotation of the transfer belt 470.

The transfer roller 475 is means for applying a transfer voltage for applying a transfer voltage for transferring (secondary transfer) the color toner image from the intermediate transfer belt 470 to transfer paper. The transfer roller 475 is disposed so as to sandwich the intermediate transfer belt 470 together with the drive roller 471.

The color toner image formed on the intermediate transfer belt 470 is transferred (secondarily transferred) from the intermediate transfer belt 470 to transfer paper by the action of the transfer roller 475.
During the secondary transfer, the transfer paper is in contact with the peripheral surface of the intermediate transfer body belt 470 while being conveyed at the process speed Vp. However, since the intermediate transfer body belt 470 bends sharply at the position of the drive roller 471, it is separated by curvature. The color toner that has been separated and transferred by being heated and pressurized by the heat fixing unit 476 is fused (fixing step), and the transfer paper on which the color image is formed passes through a discharge roller pair 481 and 482, and is discharged from a discharge tray. 409.

On the other hand, the intermediate transfer belt 470 from which the transfer paper has been separated, and the intermediate transfer belt 470
The photoconductor drums 431Y, 431Y, 431M, 431C, and 431K are cleaned by press-contact of blades (not shown) of cleaning units provided correspondingly, and the next image forming operation cycle is started.

The paper feed tray 406 is a transfer paper storage means for storing a plurality of transfer papers in a stacked state. In this embodiment, a plurality of paper feed trays 406, that is, a first paper feed tray 406A, a second paper feed tray 406B, and a third paper feed tray 406C are provided. It is arranged below the color image forming unit 403 in multiple stages. Hereinafter, since each component member corresponding to each of the paper feed trays 406A to 406C is the same,
The symbol C may be omitted.

As the transfer paper stored in the paper feed tray 406, there are media of various materials such as paper and OHP sheets (resin). The types are also different depending on the difference in the degree of conformity to the formation of a high-definition color image. For example, there are types such as coated paper, smooth paper, and plain paper. It is well known that coated paper, smooth paper, and plain paper have higher suitability for forming high-definition color images in this order.

In the present embodiment, the paper feed tray 40
6, the pickup roller 451, the separation unit 452, and the pre-registration roller 453 are unitized as a unit 450. That is, the unit 450 is provided on the front surface of the image forming apparatus so as to be integrally pulled out. Therefore, when there is no more transfer paper in the paper feed tray 406, the unit 450 can be pulled out to replenish the transfer paper. Further, when various types of transfer papers are used, paper jams are likely to occur near the feeding and separation. Therefore, when only the paper feed tray 406 is provided so as to be able to be pulled out, the jammed transfer papers are nipped by rollers. State, which complicates the processing at the time of pulling out. However, as in the present embodiment, the unit can be pulled out while being sandwiched by the rollers, thereby facilitating the processing of paper jams. It can be done reliably.

As described above, in the feeding path 405, the transfer paper stored in each of the paper feed trays 406 is transferred to the color image forming section 403 by the pickup roller 451, the separation section 452, the pre-registration roller 453, and the registration roller 455. Is conveyed. The transfer paper conveyed to the color image forming unit 403 has the toner image transferred thereon and is fixed.
The sheet passes through the discharge path 408 and is discharged to the sheet discharge tray 409 (conveying step).

The control of each component and the sequence control of the image forming operation are performed by a CPU as a control means.
(Not shown). CPU is usually
The control board is provided at an appropriate place of the image forming apparatus.

Next, the operation of the copying machine will be described with reference to FIG. 6 which is a functional block diagram of the copying machine. The color copying machine according to the present embodiment switches between two operation modes, a normal mode and a paper background registration mode, according to a user's specification, and executes the mode.
In the normal mode, the color copier obtains image data from a document placed on the platen glass 422 by the image reading unit 402, and determines a background detection level of the obtained image data based on a determination level described later (described later). Is executed to determine whether or not the background level is to be reproduced, and then the copying operation is executed. Further, in the paper background registration mode, a series of processing is performed until color information of the background of the paper such as a document or transfer paper is actually measured using the image reading unit 402 provided in the color copying machine and stored as a determination level in the normal mode. Perform the operation of

The setting / operation section 500 includes a touch panel for displaying necessary information to the user and displaying various buttons for giving an instruction to the color copier by software. The setting / operation unit 500 includes a normal mode setting button group 501, a mode shift button 502, a document background non-reproduction instruction button 503, and a color attribute match instruction button 50.
4. ACS setting section 505, paper type attribute matching instruction button 50
6, a transfer paper attribute registration mode shift button 507, an operation start button 508, and a display unit 509.

A normal mode setting button group 501 is used to input instructions necessary for the operation of a normal color copier, to select transfer paper (select paper feed tray), set the number of copies, select duplex mode, set post-processing, It consists of various buttons such as cancel.

A mode transition button 502 is a button for instructing switching between two operation modes, a normal mode and a paper background registration mode.

An original background non-reproduction instruction button 503 is used to reproduce image information other than the background in the image information read from the original without reproducing the original background level when performing color copying in the normal mode. Button for giving an instruction to the control program to perform the operation.

A color attribute match instruction button 504 is used to instruct the control program to select a transfer sheet that matches the background level of the original and execute color copy when performing color copy in the normal mode. Button to give. The transfer paper color attribute is the color attribute of the background of the transfer paper, and in the present embodiment, the color information of the background of the transfer paper in the L ^* a ^* b ^* color system and obtained from the color original. An example of processing image information will be described.

[0176] The ACS setting unit 505 is a setting unit for the user to instruct whether or not to execute the ACS. ACS
(Auto color selector) is a method in which it is determined whether or not the original is a color original. If the result of the determination is a color original, color copying is executed, and if the original is a single-color original, copying is executed in a single color. That is, if the user
If S execution is selected, one of a color copying operation and a single-color copying operation is selected and executed in accordance with the type of the document, the determination result of which is a color document or a monochrome document.
If S execution is not selected, a color copying operation is executed regardless of the document type.

The paper type attribute matching instruction button 506 is used to select a paper type suitable for color copying, such as smooth paper or coated paper, if the original is a color original when performing copying in the normal mode. After copying, if it is a monochromatic original,
Monochrome copying is performed by selecting a paper type that is not suitable for color copying such as recycled paper and plain paper but is sufficient for single-color copying and has low cost. In the color copying machine of the present embodiment, the paper size of the transfer paper
Attributes such as transfer paper color attribute data and transfer paper attribute data are stored as attributes for each tray.
If a copy is executed by selecting 06, a specific paper type is selected. Note that the transfer paper attribute is an attribute relating to the structure of the transfer paper, such as recycled paper, plain paper, smooth paper, coated paper, and the like. In general, recycled paper and plain paper have low costs, but output of color images is more difficult than smooth paper or coated paper.
On the other hand, although smooth paper and coated paper are expensive, they are suitable for color copying.

Transfer paper attribute registration mode shift button 507
Is an example of a mode switching unit of the present invention, which is an operation button for switching from the normal mode to the paper background registration mode, and is displayed on the setting / operation unit 500 while the color copying machine is on standby.

The operation start button 508 is operated by the setting / operation unit 50.
0 is a mechanical push button that is separately configured from the touch panel, and is operated by the user.
08, the color copier changes to the platen glass 422
The reading operation of the transfer paper placed on the printer is started. The operation start button 508 may double as a copy start button in the normal mode.

The display unit 509 is assigned to a part of the touch panel, and displays messages and warnings to be displayed in the normal mode or the paper background registration mode.

The image reading section 402 includes the above-described platen glass 422, image pickup device 426, and A / D conversion section 427, and further adjusts the operation of each section of the image reading section 402 when the magnification is changed in the normal mode. The scan control unit 28 is provided. The image reading unit 402 separates the image information of the original into RGB, which are the three primary colors of light, and outputs respective image data.

A / D conversion section 4 provided in image reading section 402
The color-separated image data output from 27 is subjected to shading correction and the like for each color, and then sent to an image processing unit 410 for processing.

The image processing section 510 includes the area determination processing section 51
1, first selector 512, first document background detection unit 513,
Background information storage unit 514, second selector 515, second document background detection unit 516, background information comparison unit 517, copy system processing unit 518, background removal processing unit 519, memory processing unit 52
0, a write processing unit 521 is provided.

The first original background detection unit 513 and the background information storage unit 514 belong to the paper background registration system C.
This block is used in the paper background registration mode. A second original background detection unit 516 and a background information comparison unit 517 belong to the background detection processing system D and are blocks used in the background detection processing mode. Copy processing unit 518, background removal processing unit 519, memory processing unit 520, writing processing unit 5
Reference numeral 21 denotes a block belonging to the normal processing system E and used in the normal mode.

The area determination processing section 511 is an example of the area determination means of the present invention. The area determination processing section 511 performs brightness / density conversion processing on the image data output from the image reading section 402,
An area discriminating process is executed to separate a document into characteristic portions (print / photo area and character area) and a background area, and then output normal image data and separated background data.

As image data, a background area, a character area,
There is a print / photo area, of which the character area and the print / photo area belong to the normal image area. The background area is a solid color area, and is characterized in that color information and density information do not change within a predetermined area. The character region and the print / photo region are characterized in that the density information (density level, density uniformity, density change periodicity, etc.) changes within a predetermined area. Therefore, the change of the density information can be measured and determined within an arbitrarily determined range, and the area can be separated. In the present embodiment, when no change is found in the density information of 8 × 8 pixels around the target pixel, it is determined as background data.

The character area is an area where the density information and color information change rapidly, and the print / photo area is an area where the density information and color information change gradually. The difference between the character area and the print / photo area is the difference in the degree of change in density information and color information. Various techniques for distinguishing between a character area and a print / photo area based on the degree of such a change are known.
Applicable to the present invention.

The first selector 512 includes the area discriminating unit 5
11 is a selection unit for selecting which of the paper background registration system C and the second selector 515 the image data and the background data output from 11 are to be transferred to. The first selector 512 selects a state in which the image data is transferred to the second selector 515 when the power of the color copier is turned on. When the user operates the transfer paper attribute registration mode shift button 507, the image data is detected as the first original background detection. The state passed to the unit 513 is selected. Further, a configuration may be adopted in which, when the paper background registration mode ends, a state in which the image data is automatically transferred to the second selector 515 is selected by the first selector 512.

The first original background detection unit 513 is an example of the separating means of the present invention, and is a block for executing color space processing. The background data represented by a system separated into three primary colors of RGB is inputted. Then, based on the background data, L ^*
Conversion to background data using the a ^* b ^* color system is performed. The background data in the L ^* a ^* b ^* color system, which is the conversion result, is output as data indicating color information and density information of the background of the document. The background data is information indicating color information and density information of the background area since the character area of the document has already been separated from the normal image area by the area determination processing unit 511.

The background information storage unit 514 is an example of a storage unit of the present invention, and is a block for storing detected color information and density information of the background, and a rewritable semiconductor memory or the like can be used. The background information storage unit 514 stores background color information and density information stored in advance in a program.

In the paper background registration mode, the area discrimination processing unit 511 and the first document background detection unit 513 separate the background color information and the background density information of the document from the image data.
The information is registered in the background information storage unit 514. Background information storage unit 51
At the time of registration to the paper feed tray 4, the user operates the setting / operation unit 500 to register the paper feed tray 506A, B, or C from which paper is fed.

The second selector 515 is a selection means for receiving the image data and the background data via the first selector 512 and selecting which of the background detection processing system D and the normal processing system E to transfer.

The second original background detection unit 516 detects the first original background.
A block that performs the same color space processing as the skin detection unit 513
And the color separation input through the first selector 512.
The background data and the image data represented by the
Then, based on the background data, L^*a^*b^*To color system
To the background data. L which is the conversion result^*a ^*
b^*The background data in the color system is based on the background color information of the original.
It is output as data indicating density information. Background data
Is the character area of the original by the area determination processing unit 511,
Since it is separated from the image area, the color information of the background area
This is information indicating density information.

That is, the area discrimination processing section 51 of the present embodiment
1 and the second document background detection unit 516 constitute an example of a separating unit according to the present invention. The area discrimination processing unit 511 separates the background area of the document from the image data which is an example of the color image information. The background detection unit 516 separates background color information and background density information of the document from the background data.

On the other hand, the second document background detection unit 516 receives the input
Similarly, the L ^*a^*b^*Color system drawing
Conversion to image data is performed. The second document background detection unit 516
L^*a ^*b^*Based on the image data converted to the color system,
The original read by the image reading unit 402 is a color original.
And whether the document is a monochrome document.

The background information comparison unit 517 is an example of the comparison means of the present invention, and compares the background data stored in the background information storage unit 514 with the background data output from the second original background detection unit 516. It is a block. The comparison between the background data includes a first comparison regarding background density information and a second comparison regarding background color information. Both the first and second comparisons may be performed. The background data stored in the background information storage unit 514 includes background data output from the first original background detection unit 513 and background data stored in advance in a program.

The background data stored in the program in advance and the background data output by the second original background detection unit 516 are compared. If the comparison results show that the density information is similar, color copying is performed. In this case, reproduction of the ground level is prohibited.

When the background data output by the first original background detection unit 513 and the background data output by the second original background detection unit 516 are compared, and based on the comparison result, the two color information are similar. Alternatively, when both the color information and the density information are similar, the transfer paper is fed from a specific paper feed tray 506 during color copying.

Next, the normal processing system E will be briefly described. The processing executed in the normal processing system E is a well-known technique in the field of digital color copiers, and thus description of individual processing is omitted.

The copy processing unit 518 performs spatial filtering such as moiré removal and edge emphasis corresponding to features such as character areas and image areas, scaling processing, γ conversion processing, and color separation of image data into three primary colors of RGB. L ^* a ^* from the system
b ^* Color space processing for converting to a color system is sequentially executed.

The background removal processing unit 519 converts the image data represented by the background color removal processing, the color conversion processing, and the L ^* a ^* b ^* color system into each of Y, M, C, and K image data. Processing and the like are sequentially executed.

The memory processing section 520 sequentially executes compression / expansion processing of image data, error diffusion processing, inclination correction processing, density correction processing, and the like. The writing system processing unit 521 performs a write start position synchronization process, LD control, and the like. Image reading unit 402
The image data output by is sequentially subjected to these processes in the normal processing system E and is converted into a laser drive signal. The laser driving signals are the image writing units 433Y, M,
It is a signal for determining the timing of turning on and off the laser light emitting elements of C and K.

The write processing section 530 executes laser modulation, synchronization control, and polygon motor control. The laser modulation is performed based on the laser drive signal, whereby a latent image corresponding to the image of the document is formed on the surfaces of the photosensitive drums 431Y, 431Y, 431C, 431K. Synchronous control is performed on the photosensitive drum 431Y,
This is control of writing start timing for M, C, and K, and is control for transferring toner images of each color to the surface of the intermediate transfer belt 470 so as not to shift.

The image forming system control unit 550 includes the image forming unit 43
Of the above-described members constituting 0Y, M, C, and K, chargers 432Y, M, C, and K, and developing devices 435Y, M, and C,
K, the operation of the transfer rollers 437Y, M, C, K, and a cleaning unit (not shown) are controlled. For example, when the process speed Vp is changed in accordance with the size of the transfer paper, the operation timing of these units is adjusted. The image forming system control unit 550 also executes fixing control for the heat fixing unit 476, communication control with the image processing unit 510, and the like. Since such control is a well-known technique, the description is omitted.

The transfer paper transport section 560 executes paper feed control, reverse transport control, and post-processing control. Since such control is a well-known technique, the description is omitted.

The engine control unit 570 includes a paper background registration mode control unit 570a and a paper background storage / comparison control unit 570.
b, document background non-reproduction control unit 570c, transfer paper selection control unit 570d, tray attribute comparison / selection control 570e,
In addition to the control operation of each unit, reading control, image forming system control, fixing control, communication control with the image processing unit, setting / operation unit 500
Executes communication control with.

The paper background registration mode control unit 570a includes a first paper feed tray 406A, a second paper feed tray 406B, and a third paper feed tray 406B.
The control of the procedure for registering the background data of the transfer paper stored in the paper feed tray 406C in association with each tray is executed.

The paper background storage / comparison control unit 570b stores the background data of the document read by the image reading unit 402, and stores the background data stored in advance in the program and the background data registered in association with each tray. Perform a comparison.

The original background non-reproduction control unit 570c does not execute image formation for pixels having a density lower than the density level indicated by the background data, and performs image formation for pixels having a density higher than that. Is executed.

The transfer paper selection control section 570d executes control for selecting a corresponding transfer paper based on the background data.

The tray attribute comparison / selection control 570e
In the CS control, a control for selecting a transfer sheet based on background data registered in association with each tray is executed.

In the fixing control, the control relating to the temperature management of the heat fixing unit 476 is executed so as to enable stable heat fixing and reduce energy loss.

Communication control with the image processing unit 510 controls communication of setting values and detection values required in the normal mode and the paper background registration mode. Communication control with the setting / operation unit 500
This is control for communication between the setting / operation unit 500 and the engine control unit 570 about user input contents, the operation state of the color copying machine, confirmation of user input contents, and the like.

The reading operation control is a control for the operation of the image reading unit 402. That is, when performing double-sided copying in the normal mode, image formation at the magnification selected by the user is performed for front side image formation, and image formation at the rear side magnification corresponding to the user selection is performed for back side image formation. Perform shaping.

Next, the execution procedure of the background detection processing executed in the paper background registration mode will be described with reference to the flowchart of FIG. The flowchart of FIG. 7 is a procedure executed by the paper background registration system C for image data of a transfer paper.

When the user operates the mode shift button 502 to instruct the start of the paper background registration mode, the color copying machine starts the paper background registration mode (S41). When the paper background registration mode starts, the display unit 509 displays a message prompting to operate the operation start button 508 after placing the transfer paper for which background data registration is to be performed on the document feeding table 411. It is displayed (S42). FIG. 7 shows an example in which "Please set the paper for background registration on the platen and press the copy button."

When the operation start button 508 is operated, the engine control unit 570 switches the first selector 512 so that the image data and the background data are transferred to the paper background registration system C (S43). 402
Is instructed to start the reading operation (S44).

When the reading operation of the image reading unit 402 is started, the background data separated by the area determination processing unit 511 based on the image data is obtained as described above. Background data converted to the L ^* a ^* b ^* color system is obtained (S45).

With reference to the acquired background data, L ^* >
The authenticity of 80 is verified (S46). If the verification result in step 46 is true, the background data acquired in step 45 is stored in the background information storage unit 514 as a registered value L (1) a (1) b (1) (S47).

On the other hand, if the verification result in step 46 is false, the density of the original in the background area is extremely high, and it is difficult to accurately reproduce the color information. Therefore, the background data acquired in step 45 is invalidated, and a message prompting to execute the background detection process again is displayed on the display unit 509 (S48).

Next, the execution procedure of the document preliminary scanning process will be described with reference to the flowchart of FIG.
The process of acquiring background data of a document to be read by the image reading unit 402 and determining whether or not it is necessary to reproduce the background level in the original document scanning process is a procedure mainly executed by the background detection processing system D. .

When the user presses the document background non-reproduction instruction button 503
Is operated (S51), the engine control unit 570 switches the second selector 515 so that the image data and the background data are transferred to the paper background registration system C (S5).
2), the document preliminary scanning process is started (S53).

When the preliminary scanning process starts, the image data from the image reading unit 402 is separated into normal image data and background data by the area determination processing unit 511 (S5).
4) The separated background data is sent to the paper background registration system C, and is converted into background data by the L ^* a ^* b ^* color system of the first document background detection unit 513 (S55). The actual background level value L (m) a (n) b (p) of the document read by the preliminary scan is calculated (S5).
6).

Next, the registered value L (1) a (1) b (1) stored in the background information storage unit 514 or the programmed default value L (0) a (0) b (0) is called. (S5
7) determining whether the background level value L (m) a (n) b (p) is close to the registered value L (1) a (1) b (1);
The registered value L (1) a (1) b (1) is the default value L (0) a
(0) It is determined whether it is within the range of b (0) (S5).
8) If one of them is satisfied, the background level value L
(M) The reproduction condition is changed according to a (n) b (p) (S
59) If both are not satisfied, the reproduction condition is not changed (S60). When the reproduction condition is changed, the reproduction of the background level is prohibited.

Here, the determination in step 58 will be described. For example, there is an example shown in Table 1 as a background level value L (m) a (n) b (p) obtained based on background data of a yellowed document.

[0226]

[Table 1]

In the table, white paper for color is a paper that can be used as a good transfer paper, and is given as a reference without yellowing. Other papers are used as transfer papers and originals, although they may have low reflection density or have a specific color (yellowishness).

As shown in Table 1, when an original such as recycled paper, newspaper, or postcard having density and color information on the background is used, it is difficult to determine the background only by the reflection density. However, (1) L ^* > 85 (2) −0.5 <a ^* <0.8 (3) It is not possible to set conditions satisfying the three conditions of 2 <b ^* <7 and to detect it as background information. It is possible. That is, in the color copying machine of the present embodiment, the default value L (0) a (0) satisfying such a condition is satisfied.
b (0) is set in advance, incorporated in the program, and the background level value L (m) calculated and processed in step 56
The value of a (n) b (p) is a predetermined value L (0) a (0) b (0)
It is determined in step 58 whether or not a value within the range is taken.

When a user who uses a specific recycled paper uses a color copying machine, when the user uses an image output from the color copying machine as a document to execute color copying, the recycled paper is used as a document. It may be used.
In this case, the registered value L (1) a (1) b (1) registered in advance in the paper background registration mode is called, and the background level value L (m) calculated in step 56 is processed.
The value of a (n) b (p) is the default value L (0) a (0) b (0)
It is determined whether or not approximation is made. In addition, as a criterion for approximation, when the background level value L (m) a (n) b (p) falls within about ± 1.0 of the registered value L (1) a (1) b (1). Judge as approximate.

Next, the procedure of executing the original scanning process will be described with reference to the flowchart of FIG. The flowchart of FIG. 9 is a process of executing image formation based on the determination in the document preliminary scanning process when reproducing image data read from a document, and is a procedure mainly executed in the normal processing system E.

Following the step 59 or 60 in the preliminary scan mode described with reference to FIG. 8, the user of the original document scanning process starts.

Original Document Scan Processing When the user starts,
The engine control unit 570 switches the second selector 515 so that the image data and the background data are transferred to the normal processing system E (S61), and instructs the image reading unit 402 to start the original document scanning process (S62).

When the original scanning process is started, the image data from the image reading unit 402 is separated into normal image data and background data by the area determination processing unit 511 (S6).
3) The separated normal image data and background data are sent to the normal processing system E, where conversion by the L ^* a ^* b ^* color system of the first document background detection unit 513 is performed (S64).

It is determined whether it is determined in step 59 of the preliminary scan process that the reproduction condition of the background level has been changed, or whether it has been determined in step 60 of the preliminary scan process that the normal background level reproduction process has been executed (S65). Then, the original background level non-reproduction process is executed (S66). In the original background level non-reproduction processing, normal image data is sent to the background removal processing unit 519 to perform background level removal processing. The image data on which the background level removal processing has been performed is sequentially processed in the normal processing system E, and the writing processing (S6).
Steps up to 7) are executed.

On the other hand, if it is determined in step 60 of the preliminary scan process that the normal reproduction process of the background level is to be executed, the write process is immediately executed without going through step 66 (S67). That is, although the normal image data is sent to the background removal processing unit 519, the image data is passed to the memory processing unit 520 without any processing, and is sequentially processed in the normal processing system E, until the writing process (S67). Be executed.

In executing a series of procedures from the document preliminary scan to the document original scan, the background level value L (m) a (n) b (p) is set to a predetermined value L (0) a (0).
When a value within the range of b (0) is taken, it can be considered that a yellowed document (containing color information specific to the background area) is used, and therefore, reproduction of image data belonging to the background area is performed. The reproduction condition has been changed to prohibit. Therefore, even when a document having a low reflection density but a specific color is used, the background level does not fog.

In the case where a job for copying each page of the document one or more times is performed for a plurality of pages of the document, a preliminary document scanning process and a main document scanning process are performed for each page of the document. Configuration,
Even if the reflection density and color of the document are different for each page, the background level does not fog.

Next, a description will be given of a procedure for executing the paper type matching mode including the original document pre-scanning process and the original document main scanning process for selecting a transfer sheet according to the result, with reference to the flowcharts of FIGS.

FIG. 10 is a flow chart for explaining the procedure for executing the preliminary document scanning process.

[0240] The ACS setting unit 5 executes the ACS, and further executes the color image formation in the paper type matching mode.
05 and the paper type attribute matching instruction button 506 (S71), the engine control unit 570 causes the second selector 51 to operate.
5, the image data and the background data are transferred to the normal processing system E (S72), and the document preliminary scanning process is started (S73).

When the preliminary scanning process is started, the image data from the image reading unit 402 is sent to the normal processing system E, and is converted into the background data by the L ^* a ^* b ^* color system of the first original background detection unit 513. Conversion is performed (S74). The actual level value L (m) a (n) b (p) of the document read in the preliminary scan is calculated, and it is determined whether or not a color image area exists in the document ( S7
5).

If it is determined in step 75 that the color image area does not exist, the flow advances to step 76 to store that the transfer paper attribute is plain paper. In the present embodiment, the result of the preliminary document scan is the case 1 (CASE 1).
Is stored so that the transfer paper attribute corresponds to the storage of plain paper.

If it is determined in step 75 that a color image area exists, the flow advances to step 77 to determine whether a print / photo area exists in the color image area (S77). The determination as to whether or not a print / photo area exists is made based on the output of the area determination processing unit 511.

If it is determined in step 77 that there is no print / photograph area, the flow advances to step 78 to store that the transfer paper attribute is plain paper or smooth paper. In the present embodiment, the result of the original preliminary scan is the case 2 (CA
By storing that it corresponds to SE2), the transfer paper attribute is made to correspond to the storage that it is plain paper.

If it is determined in step 77 that there is no print / photograph area, the flow advances to step 79 to store that the transfer paper attribute is coated paper or smooth paper. In the present embodiment, the result of the document preliminary scan is Case 3 (C
By storing that the transfer paper corresponds to ASE 3), the transfer paper attribute is made to correspond to the storage of plain paper.

According to the procedure from step 75 to step 79, one transfer paper attribute suitable for reproducing the image data corresponding to one screen of image data read by the image reading unit 402 is selected. In the present embodiment, three types of transfer paper attributes, plain paper, smooth paper, and coated paper, have been exemplified. However, other transfer paper attributes may also be used. It is well known that it is suitable for forming a high-definition color image in the order of coated paper, smooth paper, and plain paper.

When the transfer paper attribute is stored in any of Steps 76 to 79, the presence or absence of the corresponding transfer paper attribute is determined by referring to the transfer paper attribute corresponding to the transfer paper stored in each tray. (S80). If there is no corresponding transfer paper attribute, a warning that the setting executed in step 71 is invalid is displayed on the display unit 509 (S81).

If it is determined in step 80 that there is a corresponding transfer paper attribute, the flow proceeds to the original scanning process described with reference to FIG.

FIG. 11 is a flowchart for explaining an execution procedure of the original scanning process which is executed subsequent to the original preliminary scanning in the paper type matching mode. In this embodiment, plain paper is used for the first paper feed tray 406A, smooth paper is used for the second paper feed tray 406B, and third paper
An example in which coated paper is stored in C will be described.

When it is determined in step 80 described in FIG. 10 that there is a corresponding transfer paper attribute, the engine control unit 57
0 switches the second selector 515 (S82), and the main document scanning process is started with the image data and the background data being transferred to the normal processing system E (S83).

When the original document scanning process is started, reading from the image reading unit 402 and various image processes such as area discrimination and spatial filtering for image data are executed (S84).

Next, the result of the original preliminary scan is the case 1
It is determined which of the cases 3 corresponds to (S8)
5). In case 1, an instruction is issued to the transfer paper transport unit 560 to execute paper supply from the first paper supply tray 406A (S86). In the case 2, the transfer paper transport unit 5 is configured to perform paper supply from the second paper supply tray 406B.
60 is instructed (S87). In case 3, an instruction is issued to the transfer sheet transport unit 560 to execute sheet supply from the third sheet supply tray 406C (S88).

In step 84, the selected paper feed tray 506 is selected based on the image data subjected to various image processing.
, A color image forming process is performed on the transfer paper fed to the color image forming unit 403 (S89).

In the above-described paper type matching mode, the original data is scanned by a preliminary scan of the image data such as plain paper when the original is a monochrome original and smooth paper or coated paper when the original is a color original. Is selected from the paper feed tray 506, and if it is a color document, it is determined whether the color document contains only character information or print / photo information. In the case of color images only, smooth paper is used. When print / photo information is included, coated paper is used.
More suitable transfer paper is supplied to the paper feed tray 5 according to the substantial contents.
06.

(3) Hereinafter, the image reading apparatus and the image forming apparatus of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

FIG. 12 is a schematic diagram showing a part of the image reading device 2 provided in the copying machine shown in FIG. FIG. 13 is a schematic diagram of the transmission mechanism 220.
FIG. 12 shows the first mirror unit 23 and the V mirror unit 24 included in the image reading device 2, and the imaging lens 25 and the like are omitted. In addition, a speed change mechanism 220, a wire member 237, a first guide pulley 238, and a second guide pulley 239 are provided.

In FIG. 12, the first mirror unit 23 and the V mirror unit 24 are supported by individual guide rails (not shown) so as to be movable left and right in the figure. As described above, the first mirror unit 23 is a light source that irradiates the document with light and is a lamp 231 (see FIG. 1), which is an example of the optical lamp of the present invention, and a reflecting mirror that reflects light reflected from the document. A first mirror 232 (see FIG. 1), which is an example of the main reflecting mirror of the present invention, is integrated. Also, V
The mirror unit 24 is an example of the optical mirror group of the present invention, and as described above, the second mirror 241 (see FIG. 1) that reflects the light from the first mirror 232 and the third mirror 2
42 (see FIG. 1) and the reflected light
Lead to 5. In the following description, the first mirror unit 23 and the V mirror unit 24 are collectively referred to as a moving optical system.

The wire member 237 is connected to a driving pulley 2 described later.
35, first guide pulley 238, second guide pulley 23
9, a predetermined portion of the wire member 237 is integrally connected to the first mirror unit 23, and another predetermined portion is integrally connected to the V mirror unit 24. When operated, tension is generated, and the first mirror unit 23 and the V mirror unit 24 move. At this time, the V mirror unit 24
It moves at half speed in the same direction as the mirror unit 23.
The winding force of the wire member 237 wound several times around the driving pulley 235 causes the first mirror unit 2
3. The V mirror unit 24 is configured to be transmitted without loss.

The first guide pulley 238 and the second guide pulley 239 are moving sheaves, and the peripheral surfaces of the first guide pulley 238 and the second guide pulley 239 have a predetermined depth for winding the wire member 237. The wire member 237 has a V-shaped groove so that it does not come off when the wire member 237 rotates.

The drive motor M is a stepping motor capable of arbitrarily controlling the number of revolutions, and is a drive source for a scanning operation in the optical system.

The speed change mechanism 220 is an example of the speed change means of the present invention, and includes ten gears 221-2 having different pitch circle diameters.
The transmission of the drive is performed by changing the combination of the gears constituting the gear train and changing the reduction ratio of the drive motor M in four stages. The last stage of the speed change mechanism 220 includes a wire member 237.
Is provided.

As shown in FIG. 12, the speed change mechanism 220
Gears 221 to 230, support shafts 243 and 245, push-pull solenoids 244 and 246, butting plates 233 and 2
34, and a drive pulley 235.

The gears 221 and 222 are fixed to the drive shaft of the drive motor M, and have different pitch circle diameters. The gears 221 and 222 are restricted from moving in the thrust direction.

The gear 223 and the gear 224 are fixed to a support shaft 243 and can rotate coaxially. Also, the support shaft 243
A push-pull solenoid 244 is arranged at one end of the shaft, and the support shaft 243 is arbitrarily displaced in the thrust direction.
Change the combination of gears in the gear train.

The gears 225 and 226 are supported by a support shaft (not shown).
And can rotate coaxially. Gear 2
The movement of the gear 25 and the gear 226 in the thrust direction is restricted.

The gear 227 and the gear 228 are fixed to the support shaft 245 and can rotate coaxially. Also, the support shaft 245
A push-pull solenoid 246 is disposed at one end of the shaft, and arbitrarily displaces the support shaft 245 in the thrust direction.
Change the combination of gears in the gear train.

The gear 229 and the gear 230 are supported by a support shaft (not shown).
And can rotate coaxially. Gear 2
The movement of the gear 29 and the gear 230 in the thrust direction is restricted.

The abutment plates 233 and 234 are disk-shaped plate members sandwiched between two gears. Butt plate 23
3 is sandwiched between the gears 221 and 222,
34 is sandwiched between the gears 225 and 226.

The driving pulley 235 is provided with a concave groove for winding the driving wire several times. The drive pulley 235 is sandwiched between gears 229 and 230, similarly to the end plates 233 and 234.

Next, an example of a combination of gears forming a gear train in the transmission mechanism 220 will be described with reference to FIGS.

The gears 223 and 224 displaced in the thrust direction by the action of the push-pull solenoid 244
By abutting against the abutting plates 233 and 234, it is restricted to a position where it meshes with another gear. That is, when the gear 223 abuts against the plates 233 and 234, the rows of the gears 221, 223, and 225 mesh as part of the gear train. Similarly, when the gear 224 abuts against the abutting plates 233 and 234, the gear 22 becomes part of the gear train.
2. The rows of gear 224 and gear 226 engage.

The gears 227 and 22 displaced in the thrust direction by the action of the push-pull solenoid 246.
8 is restricted to a position where it engages with another gear by abutting against the abutting plate 234 and the driving pulley 235.
That is, the gear 227 abuts against the plate 234 and the driving pulley 2.
35, the gear 225 as part of the gear train,
The rows of the gears 227 and 229 mesh with each other. Similarly, when the gear 228 abuts against the abutting plate 234 and the driving pulley 235, the gears 226, 22
8. The rows of gears 230 engage.

FIG. 13 shows a push-pull solenoid 244.
The gear 224 abuts against the abutment plate 233 and the abutment plate 234 by the action of the gear 228, and the gear 228 abuts against the abutment plate 234 and the drive pulley 235 by the action of the push-pull solenoid 246, whereby the gear 222, the gear 224, and the gear 226 , Gear 228 and gear 230 constitute a gear train.

In the state shown in FIG. 13, both push-pull solenoid 244 and push-pull solenoid 246 are OF
F.

FIG. 14 shows a push-pull solenoid 244.
The gear 223 abuts against the abutting plate 233 and the abutting plate 234 by the action of the gear 228, and the gear 228 abuts against the abutting plate 234 and the driving pulley 235 by the action of the push-pull solenoid 246. , Gear 226, gear 228, and gear 230 constitute a gear train.

In the state shown in FIG. 14, the push-pull solenoid 244 is turned on, and the push-pull solenoid 246 is turned on.
Is turned off.

FIG. 15 shows a push-pull solenoid 244.
The gear 223 abuts against the abutting plate 233 and the abutting plate 234 by the action of the push-pull solenoid 246, and the gear 227 abuts against the abutting plate 234 and the driving pulley 235 by the action of the push-pull solenoid 246. , Gear 227 and gear 229 constitute a gear train.

In the state shown in FIG. 15, the push-pull solenoid 244 is turned off and the push-pull solenoid 244 is turned off.
6 is ON.

FIG. 16 shows a push-pull solenoid 244.
The gear 224 abuts against the abutment plate 233 and the abutment plate 234 by the action of the gear 227, and the gear 227 abuts against the abutment plate 234 and the drive pulley 235 by the action of the push-pull solenoid 246, so that the gear 222, the gear 224, and the gear 226 , Gear 225, gear 227, and gear 229 form a gear train.

In the state shown in FIG. 16, both the push-pull solenoid 244 and the push-pull solenoid 246 are turned on.
I have to.

The transmission mechanism 220 according to this embodiment is the same as that shown in FIG.
Thus, the gear ratios (in this embodiment, deceleration) can be changed in four stages by changing the combinations of the gears constituting the four gear trains shown in FIG.

Next, an example of control in which the combination of the gears forming the gear train is changed and the gears are shifted stepwise will be described with reference to the flowcharts of FIGS. FIG. 17 is a flowchart illustrating a procedure up to the start of reading according to the set reading magnification.

In the image forming apparatus, an arbitrary magnification can be set in a range of 50% to 400% in 1% steps. When the user operates the setting / operation unit 100 to set the reading magnification (S101), it calculates which block the selected reading magnification belongs to (S102). Here, the block refers to each range when the magnification selection range is divided into four, and a reading magnification of 50% to 100% is a block of range number 1, a reading magnification of 101% to 200% is a block of range number 2, Reading magnification from 201% to 30
0% is a block of range number 3 and reading magnifications from 301% to 400% are blocks of range number 4.

After calculating the range number, the gear ratio changing operation is started (S103). The push-pull solenoid 244 and the push-pull solenoid 24
By controlling the ON / OFF state of No. 6, a gear combination corresponding to the block is obtained from the four-stage gear ratio.

When the gear ratio changing operation by the push-pull solenoid 244 and the push-pull solenoid 246 is completed (S104), the number of revolutions of the drive motor M is set according to the selected reading magnification and speed ratio (S105), and step S105 is performed. Gear ratio changed in 104, and step 10
The reading operation is executed based on the number of rotations set in Step 5 (S106).

Next, the calculation in step 102 and the gear ratio changing operation in step 103 will be described in more detail with reference to FIGS.

FIG. 18 is a flowchart for explaining the calculation. In the calculation step of step 102 (FIG. 17), when the block calculation starts, it is determined whether or not the reading magnification set by the user belongs to 50% to 100% (S111). set. On the other hand, if it does not belong to the determination in step 111, the process proceeds to step 113.

In step 113, it is determined whether the reading magnification set by the user belongs to 101% to 200% (S113), and if so, the range number 2 is set (S114). On the other hand, if it does not belong to the determination in step 113, the process proceeds to step 115.

In step 115, it is determined whether or not the reading magnification set by the user belongs to 201% to 300% (S115), and if so, the range number 3 is set (S114). On the other hand, if it does not belong to the determination in step 115, the process proceeds to step 117.

In step 117, it is determined whether the reading magnification set by the user belongs to the range from 301% to 400% (S117), and if so, the range number 4 is set (S118). On the other hand, if it does not belong to the determination in step 117, the process proceeds to step 119.

Step 119 is error processing. A message to the effect that the reading magnification cannot be selected is displayed on the setting / operation section 100 for the user.

Note that steps 112, 114, 116,
Range numbers 1 to 4 set at 118 correspond to each block and the gear ratio.

FIG. 19 is a flowchart for explaining the gear ratio changing operation. In the gear ratio changing operation in step 103 (see FIG. 17), it is determined whether or not the range number set in step 102 (see FIG. 17) is 1 (S12).
1) If the range number = 1, both the push-pull solenoid 244 and the push-pull solenoid 246 are turned off (S122). On the other hand, if it is determined in step 121 that the range number is not 1, the process proceeds to step 123.

In step 123, it is determined whether or not the range number is 2, and if the range number is 2, the push-pull solenoid 244 is turned on and the push-pull solenoid 246 is turned off (S124). . on the other hand,
If the determination in step 123 is that the range number is not 2, the process proceeds to step 125.

At step 125, it is determined whether or not the range number is 3, and if the range number is 3, the push-pull solenoid 244 is turned off and the push-pull solenoid 246 is turned on (S126). . on the other hand,
If the determination in step 125 is that the range number is not 3, the process proceeds to step 127.

At step 127, it is determined whether or not the range number is 4, and if the range number is 4, the push-pull solenoid 244 and the push-pull solenoid 246 are set.
Are turned ON (S128). Step 12
If it is determined in step 7 that the range number is not 4, step 1
Go to 29.

[0297] Step 129 is error processing, and a message to the effect that the reading magnification cannot be selected is displayed on the setting / operation section 100 for the user.

In the above-described image reading apparatus 2 of the present embodiment, when the first mirror unit 23 and the V mirror unit 24 scan in the sub-scanning direction, the drive of the drive motor M is transmitted by changing the speed by the transmission mechanism 220. I do. Accordingly, it is possible to perform the scanning operation by selectively using the rotation region in which the driving motor M operates stably, and to operate the small and inexpensive motor stably so that image defects are less likely to occur and the cost is reduced. A low image reading device was realized.

The speed change mechanism 220 uses a plurality of gears having different pitch circle diameters to transmit the drive, and changes the combination of gears to change the speed stepwise. Therefore, the image reading apparatus can be made small and inexpensive.

The gear is moved in the direction of the rotation axis by using a push-pull solenoid.
The mechanism for changing the combination of gears included in the gear 20 can be reduced in size and cost.

Since the speed is changed in accordance with the reading magnification, a small and inexpensive motor can be stably used even in an image reading apparatus having a wide variable magnification range or an image forming apparatus having such an image reading apparatus. , The image reading apparatus and the image forming apparatus can be realized at a low cost and capable of reading an image in which image defects are less likely to occur.

Further, since the speed ratio of the transmission mechanism 220 is set so as to be driven in a rotation range where the rotation fluctuation of the drive motor is small, the drive motor operates stably, and the scanning of the moving optical system is stabilized.

Since the speed change ratio capable of stably operating a small and inexpensive motor is set by the speed change mechanism 220, the moving optical system is stable even if the number of rotations of the drive motor M is changed according to the reading magnification. Since scanning can be performed, image reading in which image defects hardly occur can be performed.

The range of each block is determined based on the torque characteristics of the drive motor M and the scanning speed of the moving optical system determined by the reading magnification. That is, the range of each block is determined so as to realize stable movement when changing the scanning speed of the moving optical system by controlling the rotation speed of the drive motor M. If the range of each block is determined, the number of blocks necessary to cover the reading magnification is determined naturally, so the number of steps of the speed change mechanism 220 is the same as the number of blocks.

Although the description has been given of the example of the image reading apparatus fixed to the copying machine main body, the present invention is also applicable to an image reading apparatus detachable from the copying machine main body.

[0306]

According to the image forming apparatus of the present invention, the positional accuracy of the front and back surfaces can be obtained with high precision even if the transfer paper contracts before and after fixing.

According to the color image forming apparatus of the ninth aspect, it is possible to prevent the fog image from being reproduced even when performing color copying of a color background document such as recycled paper.

According to the color image forming apparatus of the present invention, when a document has color information, it is possible to select a transfer sheet suitable for forming a color image.

According to the color image forming apparatus of the present invention, it is possible to prevent a fog image from being reproduced even when copying a color original such as recycled paper.

According to the image reading apparatus of the present invention, a small and inexpensive motor can be operated stably to realize an image reading apparatus which is less likely to cause image defects and has a low cost.

According to the image forming apparatus of the twenty-sixth aspect, a small and inexpensive motor can be operated stably to realize an image forming apparatus in which image defects hardly occur and the cost is low.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a copying machine.

FIG. 2 is a functional block diagram of the copying machine.

FIG. 3 is a flowchart illustrating an execution procedure of a size detection process.

FIG. 4 is a flowchart illustrating an execution procedure of a front / back magnification adjustment mode.

FIG. 5 is a schematic sectional view of a color copying machine as an example of the image forming apparatus of the present invention.

FIG. 6 is a functional block diagram of the copying machine.

FIG. 7 is a flowchart illustrating an execution procedure of a background detection process.

FIG. 8 is a flowchart illustrating an execution procedure of a document preliminary scan process.

FIG. 9 is a flowchart illustrating an execution procedure of a main document scanning process.

FIG. 10 is a flowchart illustrating an execution procedure of a document preliminary scan process.

FIG. 11 is a flowchart illustrating an execution procedure of a main document scanning process.

FIG. 12 is a schematic diagram illustrating a part of the image reading apparatus taken out and schematically illustrated from above.

FIG. 13 is a schematic diagram of a transmission mechanism.

FIG. 14 is a schematic diagram showing a combination example of gears forming a gear train.

FIG. 15 is a schematic diagram showing a combination example of gears forming a gear train.

FIG. 16 is a schematic diagram showing a combination example of gears forming a gear train.

FIG. 17 is a flowchart illustrating a procedure up to the start of reading according to a set reading magnification.

FIG. 18 is a flowchart illustrating calculation.

FIG. 19 is a flowchart illustrating a gear ratio changing operation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Automatic document feeder 2 Image reading device 3 Image forming unit 6 Discharge / refeed unit 22 Platen glass 23 First mirror unit 24 V mirror unit 26 CCD 38 Heat fixing unit 102 Mode shift button 103 Transfer paper size setting button 104 Transfer paper paper quality setting button 105 Display unit 111 Selector 123 Expansion / contraction ratio calculation unit 124 Expansion / contraction ratio storage unit 131a Magnification change unit 170c Magnification correction control unit 170d Time counter 220 Transmission mechanism 231 Lamp 232 First mirror 244,246 Push-pull solenoid 402 Image reading Unit 403 color image forming unit 406 paper feed tray 507 transfer paper attribute registration mode shift button 511 area discrimination processing unit 513 first original background detection unit 514 background information storage unit 516 second original background detection unit 517 background information comparison unit A Back magnification adjustment system B Normal processing system M drive motor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/01 G03G 15/01 S 5C076 Y 5C077 H04N 1/04 105 H04N 1/04 105 5C079 1/29 1 / 29 HG 1/31 1/31 1/393 1/393 1/60 1/40 D 1/40 F 1/46 1/46 Z (72) Inventor Kenji Izumimiya Konica 2,970, Ishikawacho, Hachioji City, Tokyo Inside the Company (72) Inventor Shinobu Kishi 2970, Ishikawacho, Hachioji-shi, Tokyo Konica Corporation Inside the Company (72) Eiji Nishikawa 2970, Ishikawacho, Hachioji-shi, Tokyo Inside Konica Corporation (72) Inventor Ryuji Okutomi Tokyo Konica Co., Ltd., 2970 Ishikawa-cho, Hachioji-shi (72) Inventor Masahiro Shigetomi 2970 Konica Co., Ishikawa-cho, Hachioji-shi, Tokyo F-term (reference) 2H027 DA38 DB01 DB09 DC00 DC19 DE02 EB01 EB02 EB04 EC01 EC06 EE03 FA11 FA30 FB06 FB12 FB13 FB15 FD00 FD06 GB05 ZA07 2H028 BA06 BA09 BB00 2H030 AA02 AB02 AD06 AD12 AD16 BB02 5C072 AA05 BA09 BA13 BA15 BA19 BA20 DA04 QA02 A03 MB03 CC26 DD13 DD16 DD19 DD28 EE08 EE15 FF03 FF06 FF13 FF15 GG04 GG12 GG15 GG19 HH02 5C076 AA21 AA22 BA02 BB31 CB01 CB05 5C077 LL17 LL19 MM03 MM16 MP05 MP06 MP08 PP15 PP20 SS25PP60 PP12 PP25 PP27 PP28 PP44 TT06 5C079 HB01 HB03 HB08 HB11 JA01 JA04 JA23 KA02 KA17 KA20 LA01 LA06 LA07 LA10 LA21 LA31 LA37 MA01 MA19 NA02 NA09 NA25 NA29 PA02

Claims (32)

[Claims] An image reading unit that optically scans a sheet placed on a platen to convert an electric signal converted by a photoelectric conversion element into digitized image data; and forms an image based on the image data. Magnification changing means for changing the magnification of the toner image to be printed, toner image forming means for transferring a toner image formed based on the magnification to transfer paper, heat fixing means for heating and fixing the toner image transferred to the transfer paper, one side An image forming apparatus that heats and fixes the toner image on both sides of the transfer sheet and outputs the toner image on both sides of the transfer sheet while reversing the sheet while holding the transfer sheet on which the toner image has been heated and fixed and reversing the transfer sheet. A first size detecting unit for detecting a size of a sheet before heating and fixing placed on the platen based on image data converted by the image reading unit, an image reading unit A second size detecting means for detecting the size of the sheet after heating and fixing placed on the platen based on the image data converted by the printer, and expanding and contracting from the size of the sheet before heating and the size of the sheet after heating and fixing. Expansion / contraction ratio calculating means for calculating the ratio, and magnification correction control means for determining the magnification of the toner image to be transferred to the transfer paper sent again to the toner image forming means by the reverse conveyance means based on the expansion / contraction ratio. An image forming apparatus comprising: 2. A type input means for inputting type information corresponding to the type of the sheet, an expansion / contraction ratio storage means for storing the calculated expansion / contraction ratio in association with the input type information, 2. The image forming apparatus according to claim 1, further comprising a selection unit that selects a desired expansion / contraction ratio adjustment mode and a duplex copying mode in which an image is formed at the determined magnification. 3. 3. A size input means for inputting size information corresponding to the size of the sheet; an expansion / contraction ratio storage means for storing the calculated expansion / contraction ratio in correspondence with the input size information; 3. The image forming apparatus according to claim 1, further comprising: a selection unit configured to select an expansion / contraction ratio adjustment mode for obtaining the magnification and a duplex copying mode in which an image is formed at the determined magnification. 4. The expansion / contraction ratio storage means can store a plurality of the expansion / contraction ratios.
An image forming apparatus according to claim 1. 5. The image reading unit includes a platen cover that blocks light that passes through a platen and enters the photoelectric conversion unit. The first size detection unit and the second size detection unit include a platen cover. 5. The image forming apparatus according to claim 1, wherein the size of the sheet placed on the platen in an opened state is detected. 6. The first size detecting means separates the image data into black and white pixel information of a certain level, detects the size of the sheet before heat fixing based on the number of white level pixels, and 3. The apparatus according to claim 1, wherein the second size detecting unit separates the image data into black and white pixel information of a fixed level and detects the size of the sheet after fixing based on the number of white level pixels. 6. The image forming apparatus according to 3, 4, or 5. 7. A time measuring means for measuring a time interval of size detection executed by the first size detecting means and the second size detecting means, and the first size detecting means when the time interval exceeds a predetermined time. 7. The image forming apparatus according to claim 1, further comprising: a unit and an invalidating unit that invalidates a detection result of the second size detecting unit. 8. The image forming apparatus according to claim 1, further comprising a warning unit that issues a warning when the invalidation unit invalidates the detection result. 9. A color image forming apparatus comprising: an image reading unit that reads color image information from a document; and a color image forming unit that outputs a color image according to image forming conditions based on the read color image information. Separating means for separating color information and density information of the background of the document from the information, and control means for changing the image forming conditions according to the color information and density information of the background of the separated document. Color image forming apparatus. 10. A storage means for storing background color information and background density information of a document, and background color information and density information of the document obtained by separating the stored background color information and density information of the document. 10. The color image forming apparatus according to claim 9, further comprising comparison means for comparing, wherein the control means switches a reproduction level between background color information and density information of the document according to the comparison result. 11. The color image forming apparatus according to claim 9, wherein said storage means stores in advance color information and density information of the background of an arbitrary document. 12. The image processing apparatus according to claim 9, further comprising a mode switching unit for switching to a background information registration mode in which the background color information and the density information of the document separated by the separation unit are stored in the storage unit. Or the color image forming apparatus according to 11. 13. The apparatus according to claim 9, wherein said control means performs image processing that does not reproduce background information of the document.
13. The color image forming apparatus according to 0, 11 or 12. 14. The color image forming apparatus according to claim 9, wherein said image processing is processing for reproducing a background level of a document as a white level. 15. The control device according to claim 1, wherein the control unit is configured not to reproduce a part of the color image information read by the image reading unit, the part corresponding to the stored background color information and density information of the document. 15. The color image forming apparatus according to claim 9, further comprising a setting unit that performs a reproduction process and instructs execution of the background level non-reproduction process. 16. An image reading section for reading color image information and monochrome image information from a document, a plurality of paper feed trays, and a color image on transfer paper fed from a paper feed tray based on the read color image information. A color image forming apparatus including an image forming unit that outputs the background color information of the document from the color image information; a classifying unit that classifies the document based on the separated background color information; A selection means for assigning an attribute to each paper feed tray in accordance with the classification of the transfer paper stored in each paper feed tray, and a paper feed tray to which an attribute matching the classification of the original is provided are selected. A color image forming apparatus which forms an image by feeding transfer paper from a paper tray. 17. An attribute corresponding to monochrome transfer paper or color transfer paper stored in the plurality of paper feed trays, and an attribute corresponding to color transfer paper when color image information is read. The color image forming apparatus according to claim 16, wherein a paper feed tray provided with a character is selected. 18. An image processing apparatus comprising: an area determining unit configured to determine whether a character area and a print / photo area are included in the color image information. When the color image information includes only a character area, the color image information corresponds to a monochrome transfer sheet. A paper feed tray provided with an attribute corresponding to a color transfer paper when a color / image area is included in the color image information when a print / photo area is included 2. A color image forming apparatus is selected to execute color image formation.
18. The color image forming apparatus according to 6 or 17. 19. A color image forming apparatus comprising: an image reading unit that reads color image information from a document; and an image forming unit that outputs a color image to transfer paper based on the read color image information. The part where the constant density and color information are continuous is the background area of the original,
A mode for setting an image processing condition for prohibiting the reproduction of the background area of the document; a means for determining an area occupancy of the background area with respect to the entire area; A color image forming apparatus comprising: selecting means for prohibiting reproduction of the background area of the document in accordance with the occupancy. 20. An image reading apparatus for reading image information from an original on a platen by scanning an optical lamp, a main reflecting mirror, and an optical mirror group in a sub-scanning direction. Optical lamp and main reflector,
An image reading apparatus comprising: a shift unit that shifts a scanning speed of a group of optical mirrors. 21. The transmission device according to claim 20, wherein the transmission means transmits the drive by using a plurality of gears having different pitch circle diameters, and changes the combination of the gears to change the speed stepwise.
The image reading device according to claim 1. 22. A push-pull solenoid for moving the gear in the rotation axis direction, and magnification control means for setting a reading magnification of a document image, wherein the gear is controlled by the push-pull solenoid according to the set reading magnification. 22. The image reading device according to claim 21, wherein the shift is performed by moving the image reading device. 23. The image reading apparatus according to claim 21, wherein said speed change ratio is set so as to be driven in a rotation range where rotation fluctuation of said drive motor is small. 24. The image reading apparatus according to claim 21, wherein the rotational speed of the drive motor is controlled according to the magnification in a state where each speed ratio of the speed change means is determined. 25. The speed change device according to claim 22, wherein the speed change means can change the speed in at least four steps.
The image reading device according to claim 1. 26. Image reading means for scanning an optical lamp, a main reflecting mirror, and an optical mirror group in a sub-scanning direction to read image information from a document on a platen, and forming an image by electrophotography based on the read image information. In an image forming apparatus provided with an image forming unit for forming, a driving motor as a driving source of the image reading unit, and a shift unit for transmitting a drive to change a scanning speed of the optical lamp, the main reflecting mirror, and the optical mirror group. An image forming apparatus comprising: 27. The transmission device according to claim 26, wherein the transmission means transmits the drive by using a plurality of gears having different pitch circle diameters, and changes the combination of the gears to change the speed stepwise.
An image forming apparatus according to claim 1. 28. A push-pull solenoid for moving the gear in the direction of a rotation axis, and magnification control means for setting a magnification for reading a document image. 28. The image forming apparatus according to claim 27, wherein the shift is performed by moving the image forming apparatus. 29. The image forming apparatus according to claim 27, wherein the speed ratio is set so as to be driven in a rotation range where the rotation fluctuation of the drive motor is small. 30. The image forming apparatus according to claim 27, wherein the rotational speed of the drive motor is controlled in accordance with the magnification in a state where each speed ratio of the speed change means is determined. 31. The speed change device according to claim 28, 29 or 3, wherein the speed change means can change the speed in at least four steps.
0. The image forming apparatus according to item 0. 32. Magnification input means for inputting a magnification desired by a user, wherein the magnification control means controls a reading magnification in accordance with the desired magnification.
The image forming apparatus according to 6, 27, 28, 29, 30, or 31.