JPH11222334A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily set start timing of image formation so as to be able to smoothly form images in the heightened state of printing speed in an image forming device that conveys a plurality of rectangular paper successively in a state of substantially no paper space along a conveying path. SOLUTION: This image forming device conveys a plurality of rectangular paper P successively in a state of substantially no paper space along a belt-like conveying path 40 and forms an image on the paper P in a specific position on the conveying path 40 with respect to a conveying direction X. The paper P following the preceding paper P is conveyed in a state of being shifted in the position from the preceding paper P with respect to one direction vertical to the conveying direction X within a plane along the conveying path 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus. More specifically, the present invention relates to an image forming apparatus that sequentially conveys a plurality of rectangular sheets through a conveyance path in a state where there is substantially no sheet interval, and forms an image on the sheet at a specific position on the conveyance path.

[0002]

2. Description of the Related Art In an image forming apparatus which performs an electrophotographic process such as a copying machine or a printer, a plurality of rectangular sheets are arranged in a line at a constant sheet interval. 2. Description of the Related Art There has been widely used a method in which an image (toner image) formed on a photosensitive drum is sequentially conveyed through a conveyance path and transferred to the sheet at a transfer position on the conveyance path. The timing for starting image formation on the photosensitive drum is
The output is set based on a change in the output of the sheet sensor provided on the transport path, specifically, the timing at which the leading edge of each sheet is detected. In this method, the number of sheets processed per unit time (hereinafter, referred to as “print speed”) because of the paper interval.
Has limitations.

Therefore, recently, in order to increase the printing speed, a method has been studied in which a plurality of rectangular sheets are sequentially conveyed through a conveying path in a state where there is substantially no space between the sheets.

However, if the paper interval is simply eliminated, the paper sensor provided on the transport path always detects the paper, and the leading edge of each paper cannot be detected. For this reason, there is a problem that the timing for starting image formation on the photosensitive drum cannot be set.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to simultaneously transport a plurality of rectangular sheets through a transport path in a state where there is substantially no sheet interval, and to easily set the start timing of image formation. An object of the present invention is to provide an image forming apparatus capable of forming an image smoothly at a high speed.

[0006]

According to a first aspect of the present invention, there is provided an image forming apparatus, wherein a plurality of rectangular sheets are sequentially transferred to a belt-like transport path with substantially no sheet interval. In an image forming apparatus that conveys a sheet along a conveying direction and forms an image on the sheet at a specific position on the conveying path with respect to the conveying direction, a sheet following the preceding sheet is moved along the conveying path with respect to a preceding sheet. The conveyance is performed in a state where the position is shifted in one direction perpendicular to the conveyance direction in the plane.

Here, "substantially no paper interval" means that the distance in the transport direction between the preceding paper and the following paper is set to zero except for unintended errors. Means that

In the image forming apparatus according to the first aspect, a sheet following the preceding sheet is positioned relative to a preceding sheet in a direction perpendicular to the transport direction in a plane along the transport path. Is transported in a shifted state, so that the leading edge of the next succeeding sheet can be easily detected based on the positional deviation. That is, since the leading edge of the sheet following the preceding sheet is shifted to one side in the one direction with respect to the trailing edge of the preceding sheet, the leading edge of the next sheet conveyed in the shifted state Should be detected. In such a case, the start timing of image formation can be easily set, and each sheet and the image will not be displaced in the transport direction. Therefore, image formation is performed smoothly with the print speed increased.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus has two paper feeding ports provided at positions different from each other in the one direction, and the two paper feeding ports are provided. The paper feeding means for feeding the paper to the transport path by alternately passing through a mouth is provided.

According to the image forming apparatus of the present invention, the sheet feeding means feeds the sheet to the conveyance path alternately through two sheet feeding ports provided at different positions in the one direction. The sheet is conveyed in a state of being alternately displaced in the one direction.

According to a third aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the conveying direction is the upstream side of a specific position where the image is to be formed in the conveying direction and the conveying direction is in the one direction. The paper sensors are arranged at positions corresponding to both sides of the road, respectively.

According to the image forming apparatus of the present invention, each of the sheet sensors can detect a sheet conveyed in a state of being shifted every other sheet toward the sensor in the one direction. Therefore, the leading end of each sheet conveyed sequentially can be detected based on the output change of the sheet sensors on both sides. Therefore, the start timing of image formation can be easily set based on the detection timing of the leading edge of each sheet, and each sheet and the image are not displaced in the transport direction. As a result, the image is formed smoothly with the print speed increased.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, an image is formed in the one direction on the transport path according to the position of the sheet sequentially transported in the one direction. An area setting means for setting the area by moving the area is provided.

In the image forming apparatus according to the fourth aspect, the area setting means moves and sets the image forming area in the one direction on the conveying path according to the position of the sequentially conveyed paper in the one direction. As a result, each sheet and the image are not displaced in the one direction with respect to the preceding sheet, even though the position of the sheet following the sheet is shifted in the one direction. Image formation is properly performed on the top.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, a central axis extending along the one direction so as to contact the sheet at the specific position on the transport path. The image forming area is moved and set along the one direction on the outer peripheral surface of the photosensitive drum in accordance with the position of the photosensitive drum having An area setting means for setting an optical density measurement area in an area other than the image forming area on the outer peripheral surface of the drum is provided.

In the image forming apparatus according to the fifth aspect, the area setting means sets the image forming area on the outer peripheral surface of the photosensitive drum along the one direction in accordance with the position of the sequentially conveyed paper in the one direction. The optical density measurement area is set in an area other than the image forming area on the outer peripheral surface of the photoconductor drum. Therefore, the optical density measurement area is set on the outer peripheral surface of the photosensitive drum without overlapping the image forming area, even though the paper is sequentially conveyed with substantially no paper interval. As a result, the optical density of the original image formed in the image forming area can be controlled based on the optical density of the optical density measuring mark formed in the optical density measuring area.

Also, since the area setting means moves and sets the image forming area along the one direction on the outer peripheral surface of the photosensitive drum according to the position of the sequentially conveyed paper in the one direction. In spite of the fact that the position of the sheet following the sheet is shifted in the one direction with respect to the preceding sheet, each sheet is not shifted from the original image in the one direction, Image formation is properly performed on the top. Then, the original image formed in the image forming area is transferred to the sheet by rotating the photoconductor drum around the central axis at the specific position on the transport path and abutting the sheet. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the image forming apparatus of the present invention will be described in detail.

FIG. 1 shows a cross section of an image forming apparatus according to an embodiment.

The image forming apparatus 1 includes a cylindrical photosensitive drum 10 that extends in one direction perpendicular to the cross section in FIG. 1 at a specific position on the transport path 40 substantially at the center of the image forming apparatus.
The photosensitive drum 10 is driven to rotate in the direction of arrow a by a motor (not shown) so as to come into contact with a sheet P conveyed on the conveyance path 40.

In order to execute an electrophotographic process, a charger 11 and a developing device 12 are provided around the photosensitive drum 10.
, A transfer device 14, a paper separating device 15, a cleaning device 16, and an eraser lamp 17 are provided in this order.

When the electrophotographic process is performed, first, the outer peripheral surface of the photosensitive drum 10 is charged by the charger 11. Next, a laser scanning optical system 2, which will be described later, irradiates the charged outer peripheral surface of the photosensitive drum 10 with laser light based on image data input from an external device (for example, an image scanner or the like), and An electrostatic latent image is formed. The electrostatic latent image is developed by the developing device 12 to form a toner image on the outer peripheral surface of the photosensitive drum 10. At the transfer position on the transport path 40, the outer peripheral surface of the photosensitive drum 10 is
This toner image is transferred to the sheet P by contacting the sheet P conveyed above. The sheet P to which the toner image has been transferred is conveyed by the conveying belt 31 and sent to the fixing roller 32. The toner image transferred to the sheet P is pressed and heated by the fixing roller 32 and is fixed on the sheet P. The paper (print) after the image is fixed is discharged onto a discharge tray 34 through a discharge roller 33.

The laser scanning optical system 2 is provided above the image forming apparatus 1. As shown in FIG. 3, the laser scanning optical system 2 includes a laser diode 41 as a laser light source, a collimator lens 42 for condensing laser light emitted from the laser diode 41, and a polygon mirror 4
3 and an f-θ lens 45. The laser light emitted from the laser diode 41 is condensed by the collimator lens 42 and enters the polygon mirror 43. The polygon mirror 43 is rotated at high speed around a vertical axis by a polygon motor 44. The laser light reflected by one reflecting surface of the rotating polygon mirror 43 passes through the f-θ lens 45 and is directed horizontally to the outer peripheral surface of the photosensitive drum 10 (this is referred to as a main scanning direction).
Is scanned. A mirror 47 is provided adjacent to the outer peripheral surface of the photosensitive drum 10 for receiving a laser beam that has been swung over the outer peripheral surface of the photosensitive drum 10 before scanning by each reflection surface of the polygon mirror 43 is started. I have. This mirror 4
The light reflected by 7 is detected by an optical sensor 48. Therefore, the output signal of the optical sensor 48 (hereinafter referred to as “SOS
Signal. ), The write start position in the main scanning direction can be synchronized on the outer peripheral surface of the photosensitive drum 10.

As shown in FIG. 1, the image forming apparatus 1 includes a paper feed cassette 2 disposed in three stages as a paper feed port.
1, 22, 23 are provided. As shown in FIGS. 2A and 2B, the upper sheet cassette 21 and the middle sheet cassette 22
Claws 24a, 2 provided for positioning the paper P are provided inside a rectangular tray 20 having edges on all sides.
4b and 24c. On the edge 21 a of the upper paper cassette 21 on the side of the transport path 40, the paper P is transported one by one to the transport path 4.
A pair of paper feed rollers 25, 25 for feeding the paper to zero are provided. Similarly, the transport path 4 of the middle sheet cassette 22
A pair of paper feed rollers 26 for feeding the paper P to the transport path 40 one by one is provided on the edge 22a on the 0 side. The upper paper feed cassette 21 has an edge 2 on the conveyance path 40 side.
A plurality of sheets P of rectangular and the same size are set at positions in contact with the front edge 21b adjacent to 1a.
On the other hand, the middle sheet cassette 22 has
A plurality of sheets P of the same size as the sheet P set in the rectangular upper sheet cassette 21 are set at a position separated from the front edge 22b adjacent to the sheet 2a and in contact with the claw 24c on the opposite side. Have been. During operation, the paper feed rollers 25 of the upper paper cassette 21 and the middle paper cassette 22
The paper feed rollers 26, 26 operate alternately, and the paper P is alternately sent out from the respective paper feed cassettes 21, 22 to the transport path 40 one by one. This means that, as shown in FIG. 3, a sheet P following the preceding sheet P is moved in a plane along the conveying path 40 in the Y direction perpendicular to the conveying direction X, as shown in FIG. This is because the sheet is transported in a state where the position is alternately shifted to the back side and the near side. At this time,
By controlling the operation timing of the middle sheet feeding rollers 25 and 26, the preceding sheet P and the succeeding sheet P are controlled.
Is set to a state in which there is substantially no sheet (zero). The lower paper cassette 23 is larger than the upper paper cassette 21 and the middle paper cassette 22, and can be set to a size larger than the paper P. The paper set in the lower paper cassette 23 is sent out to the transport path 40 by the paper feed roller 27 and the vertical transport roller 28 (however, the lower paper cassette 23 is not used in the following description).

FIG. 6 schematically shows the transport path 40 as viewed from above. The As can be seen from FIG. 6, on the upstream side of the transfer position X ₁ with respect to the conveying direction X, and both sides Bo of the transport path 40 in the Y-direction, respectively the paper sensor 93 and 94 at a position corresponding to the Be is located. Each of the paper sensors 93 and 94 is of a type that detects a portion of the paper P that passes immediately above the sensor. Paper sensors 93 and 94
, The sheet sensor 93 on the back side detects only the sheets P ₁ , P ₃ , P ₅ ,... Which are conveyed every other sheet to the sensor 93 side in the Y direction, while The sheet sensor 94 on the side can detect only the sheets P ₂ , P ₄ ,... Which are conveyed while being shifted every other sheet in the Y direction toward the sensor 94 side. Therefore, based on the output change of the paper sensors 93 and 94 on both sides (the output of each paper sensor 93 and 94 is ON when the paper P is detected, and OFF when the paper P is not detected). each sheet P ₁ being sequentially _{conveyed, P 2, P 3, P} 4, P 5, can be detected ... tip of. Thereby, the paper sensors 93, 9
4 is the position X _{0 of the} leading edge of the sheet when the leading edge of the sheet P is detected.
And the transport speed V of the paper P, it is possible to set the writing start timing in the transport direction of the paper P (corresponding to the sub-scanning direction on the photosensitive drum 10).

More specifically, the position X ₀ of each of the paper sensors 93 and 94 in the transport direction X is located upstream from the transfer position X _{1 by} a distance corresponding to one to two paper sizes. Thus, for example, when the sheet P ₁ is passed through the transfer position X _1, the paper passes through the position X ₀ of the sheet sensor 93 or 94 is a sheet P _2. Writing timing in the sub-scanning direction on the photosensitive drum 10, the leading end of the sheet P continues on the next sheet being currently transferred is a time of reaching the position X _i in FIG. Distance in the conveying direction between the X _i and X ₁ corresponds to the circumferential length between the transfer position and the laser beam scanning position on the photosensitive drum 10.

FIG. 4 shows a block configuration of a control system 90 of the image forming apparatus 1. The control system 90 includes a microcomputer 9 for controlling the operation of the entire image forming apparatus 1.
1, a clock generation circuit 92 for generating a reference clock pulse for the microcomputer 91, a laser diode driver 97 for rotating and driving the polygon motor 44 of the laser scanning optical system 2, and image data capable of storing image data. A memory 96 is provided.

Image data input from an external device (such as an image scanner) is temporarily stored in an image data memory 96 and sent to a laser diode driver 97 according to an instruction from a microcomputer 91. The laser diode driver 97 drives the laser diode 41 of the laser scanning optical system 2 under the control of the microcomputer 91, and makes the laser diode 41 emit laser light modulated according to the image data.

The microcomputer 91 receives an SOS signal from the laser scanning optical system 2 and output signals from the paper sensors 93 and 94. Microcomputer 91
As described above, the writing position in the main scanning direction on the photosensitive drum 10 is synchronized based on the SOS signal from the optical sensor 48, and the paper sensors 93 and 94
The image forming area in the main scanning direction on the photosensitive drum 10 is moved and set on the basis of the output signal from. That is, as shown in FIG. 3, when the output of the paper sensor 93 on the rear side changes from OFF to ON, the image forming area for the paper P following the paper currently being transferred is changed to the rear area. On the other hand, when the sheet sensor 94 on the near side changes from OFF to ON, the image forming area for the sheet P following the sheet currently being transferred is set as the area Ie on the near side.
The microcomputer 91 further includes a paper sensor 93,
The writing start timing in the sub-scanning direction on the photosensitive drum 10 is set based on the output signal from 94. In addition, the microcomputer 91 inputs and outputs necessary signals to and from each unit of the image forming apparatus 1 and inputs and outputs necessary signals to and from an external device.

On the upper surface of the image forming apparatus 1, there is provided an operation panel 70 for an operator to perform various input operations on the image forming apparatus 1 as shown in FIG. The operation panel 70 includes a print start key 71 for starting a print operation, a user interrupt key 72 for designating an interrupt print, a clear / stop key 73, an all reset key 74, a ten key 75, a set key 76, a cancel key. A key 77, jog dials 82 and 83, and a liquid crystal display 84 for displaying various messages are provided.

The image forming apparatus 1 operates as a whole according to an operation flow (main routine of the microcomputer 91) shown in FIG.

When the power is turned on and the microcomputer 91 is reset, first, initial settings are performed (S1). That is, various registers are initialized, and the operation mode is set to the initial mode.

Next, an internal timer is started (S2). This internal timer determines the time required for one cycle of the main routine shown in FIG. 7 irrespective of the processing contents of the subroutine. Note that the time until the counting by the internal timer is completed is set in advance in the initial setting in step S1.

Next, paper selection is performed (S
3). That is, a sheet on which an image is to be formed is selected in accordance with an input by the operator through the operation panel 70 or an input from an external device. Here, the paper P of the size set in the upper paper cassette 21 and the middle paper cassette 22 in FIG.
It is assumed that the sheets P are alternately sent out onto the transport path 40 as shown in FIGS. Upper paper cassette 21
And the paper setting position in the middle paper cassette 22,
The sheet P to be conveyed is in a state of being alternately displaced to the rear side and the front side in the Y direction perpendicular to the conveyance direction X in the plane along the conveyance path 40. The microcomputer 91 controls the operation timings of the upper and middle paper feed rollers 25 and 26 so that the sequentially conveyed paper P,
The paper interval between P,... Is set to a substantially non-existent state (zero).

Next, a printing operation is performed (S4).

I) More specifically, as shown in FIG. 8, first, it is determined whether or not the output of the paper sensor 93 on the back side has changed from OFF to ON, that is, whether or not the paper P has been detected (S).
41). If the output of the paper sensor 93 on the back side is turned on and the paper P is detected, the image forming area on the photosensitive drum 10 is moved in the main scanning direction for the paper P following the currently transferred paper. It is set in the back side area Io (see FIG. 3) (S43).

On the other hand, if the rear paper sensor 93 is not ON, the output of the front paper sensor 94 is OFF.
Then, it is determined whether or not the sheet P has been turned on, that is, whether or not the sheet P has been detected (S42). If the output of the paper sensor 94 on the front side is turned ON and the paper P is detected, the photosensitive drum 10
The upper image forming area is the area I on the near side with respect to the main scanning direction.
e (S44).

Ii) A timer (not shown) for setting a writing start timing in the sub-scanning direction on the photosensitive drum 10 when the paper sensor 93 on the back side or the paper sensor 94 on the front side detects the leading end of the paper P. Is started (S45). The time to be counted by the timer is predetermined based on the position X _{0 of the} leading edge of the sheet when the sheet sensor 93 or 94 detects the leading edge of the sheet P, and the transport speed V of the sheet P.

Iii) Next, in step S46, it is determined whether or not the counting by the timer has been completed. At the time when the counting by the timer is completed, the laser by the laser scanning optical system 2 is applied to the image forming area Io on the back side or the image forming area Ie on the near side set on the photosensitive drum 10 according to the input image data. Start light irradiation. By the irradiation of the laser beam, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 10. The electrostatic latent image is developed by the developing device 12 to form a toner image on the outer peripheral surface of the photosensitive drum 10. The toner image is transferred to the sheet P at the transfer position X ₁ on the conveying path 40. The paper (print) P on which the toner image has been transferred is discharged onto a discharge tray 34 after fixing.

As described above, based on the output signals from the paper sensors 93 and 94, the image forming area I on the photosensitive drum 10
Since o and Ie are alternately set with respect to the main scanning direction (Y direction), each of the sheets P conveyed sequentially on the conveyance path 40 is displaced in the Y direction even though they are alternately displaced in the Y direction. The paper P and the original image are not displaced in the main scanning direction. Further, since the writing timing in the sub-scanning direction on the photosensitive drum 10 is set based on the detection timing of the leading end of each sheet P by the sheet sensors 93 and 94, each sheet P and the image are There is no displacement. As a result, an image can be formed smoothly with the print speed increased.

Iv) If the counting by the timer has not been completed, another printing operation is executed in step S48, and the flow advances to step S5 in the main routine (FIG. 7).

Thereafter, if there is a request for interrupt printing by the user, interrupt printing is executed (S5), and communication with another CPU (Central Processing Unit) is performed as needed (S6). Then, the process returns to step S2 after the internal timer has finished counting.

In the electrophotographic process, before forming an original toner image on the photosensitive drum, a toner mark (AIDC mark) for measuring optical density is formed, and based on the optical density of the toner mark, In many cases, the optical density of the original toner image is controlled.

In the image forming apparatus 1, the microcomputer 91 functions as an area setting unit, and alternately sets the image forming area on the photosensitive drum 10 to the back side or the front side in the main scanning direction as described above. At the same time, an optical density measurement area is set in an area other than the image forming area on the outer peripheral surface of the photosensitive drum 10. For example,
In FIG. 3, if the image forming area currently being written is the back side area Io, the optical density measurement area is set to the near side, while if the image forming area currently being written is the near side area Ie. , The optical density measurement area is set on the back side. Accordingly, the optical density measurement area can be set on the outer peripheral surface of the photosensitive drum 10 without overlapping the image forming areas Io and Ie, even though the paper is sequentially conveyed with substantially no paper interval. . As a result, the optical density of the original image formed in the image forming area Io or Ie can be controlled based on the optical density of the toner mark formed in the optical density measurement area.

The sensors for measuring the optical density may be moved in accordance with the area for measuring the optical density, or may be provided in advance at two positions in the main scanning direction, that is, on the far side and on the near side. For reference, the position of the optical density measurement area 60 set on the near side is shown in FIG.

In this embodiment, the paper P sequentially conveyed
Is alternately shifted to the rear and front sides in the Y direction in the plane along the transport path 40, but is not limited to this. The paper P sequentially conveyed may take three or more different positions in the Y direction in the plane along the conveyance path 40.

Further, the set position of the paper P with respect to the tray 20 in the paper feed cassettes 21 and 22 is shifted in the Y direction, but the present invention is not limited to this. Tray 20
And the paper cassettes 21 and 22 themselves may be shifted from each other in the Y direction and mounted on the apparatus 1 body.

Further, the present invention is applicable not only to the case where a toner image is formed on the photosensitive drum 10 and transferred to the sheet P, but also to the case where an image is formed directly on the sheet P conveyed on the conveyance path 40. Applicable. In this case as well, by shifting the sequentially conveyed paper P in the Y direction within the plane along the conveyance path 40, the leading edge of the paper P following the preceding paper P can be easily adjusted with respect to the preceding paper P. Can be detected. Therefore, the start timing of image formation can be easily set.

[0049]

As is apparent from the above description, in the image forming apparatus according to the first aspect, the leading end of the sheet following the preceding sheet can be easily detected. Can be easily set, and each sheet and the image are not displaced in the transport direction. Therefore, it is possible to form an image smoothly with the print speed increased.

In the image forming apparatus according to the second aspect, the sheet feeding means feeds the sheet to the conveyance path alternately through two sheet feeding ports provided at different positions in the one direction. Are conveyed in a state where they are alternately displaced in one direction.

According to the image forming apparatus of the present invention, each sheet sensor moves one direction to the sensor side in the one direction.
Since the paper conveyed in a shifted state can be detected for each sheet, the leading edge of each paper conveyed sequentially can be detected based on the output change of the paper sensors on both sides. Therefore, the start timing of image formation can be easily set based on the detection timing of the leading edge of each sheet, and each sheet and the image are not displaced in the transport direction. As a result, an image can be formed smoothly with the print speed increased.

In the image forming apparatus according to the fourth aspect, the area setting means moves and sets the image forming area in the one direction on the conveying path in accordance with the position of the sequentially conveyed paper in the one direction. As a result, each sheet and the image are not displaced in the one direction with respect to the preceding sheet, even though the position of the sheet following the sheet is shifted in the one direction. Image formation is properly performed on the top.

In the image forming apparatus according to the fifth aspect, the area setting means moves the image forming area along the one direction on the outer peripheral surface of the photosensitive drum according to the position of the sequentially conveyed paper in the one direction. In addition, since the optical density measurement area is set in an area other than the image forming area on the outer peripheral surface of the photoconductor drum, the paper is sequentially conveyed with substantially no paper interval. Nevertheless, the optical density measurement area can be set on the outer peripheral surface of the photosensitive drum without overlapping the image forming area. As a result, the optical density of the original image formed in the image forming area can be controlled based on the optical density of the optical density measuring mark formed in the optical density measuring area.

Since the area setting means moves and sets the image forming area on the outer peripheral surface of the photosensitive drum along the one direction in accordance with the position of the sequentially conveyed paper in the one direction. In spite of the fact that the position of the sheet following the sheet is shifted in the one direction with respect to the preceding sheet, each sheet is not shifted from the original image in the one direction, An image can be properly formed on the top.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a cross section of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a sheet cassette of the image forming apparatus.

FIG. 3 is a perspective view illustrating a main part of the image forming apparatus.

FIG. 4 is a diagram illustrating a block configuration of a control system of the image forming apparatus.

FIG. 5 is a diagram showing an operation panel of the image forming apparatus.

FIG. 6 is a diagram schematically illustrating a sheet conveyance path of the image forming apparatus when viewed from above.

FIG. 7 is a view showing a schematic flow of an operation of the image forming apparatus.

FIG. 8 is a diagram illustrating a flow of a printing operation of the image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Laser scanning optical system 10 Photoreceptor drum 21, 22, 23 Paper feed cassette 34 Discharge tray 40 Transport path

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Minoru Nakamura 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Tatsuya Eguchi Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Osaka Metropolitan Building Minolta Co., Ltd. (72) Inventor Masanobu Onohara 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka

Claims (5)

[Claims] 1. A plurality of rectangular sheets are sequentially conveyed along a belt-shaped conveyance path with substantially no sheet interval, and an image is formed on the sheet at a specific position on the conveyance path in the conveyance direction. In the image forming apparatus, a sheet following the preceding sheet is conveyed in a plane along the conveyance path in a state shifted in one direction perpendicular to the conveyance direction. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, further comprising two paper feed ports provided at different positions in the one direction, and passing the two paper feed ports alternately. An image forming apparatus, further comprising a sheet feeding means for feeding the sheet. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is located at an upstream side of a specific position where the image is to be formed in the transport direction and at a position corresponding to both sides of the transport path in the one direction. An image forming apparatus, wherein a paper sensor is arranged. 4. The image forming apparatus according to claim 1, wherein an image forming area is set by moving an image forming area in the one direction on the conveyance path in accordance with a position of the sheet sequentially conveyed in the one direction. An image forming apparatus comprising: 5. The image forming apparatus according to claim 1, wherein the photosensitive drum having a central axis extending along the one direction so as to contact the sheet at the specific position on the transport path; The image forming area is moved along the one direction on the outer peripheral surface of the photoconductor drum in accordance with the position of the sheet to be formed in the one direction, and the image forming area is formed on the outer peripheral surface of the photoconductor drum. An image forming apparatus comprising: an area setting unit that sets an optical density measurement area in an area other than the area.