JPH0685044B2 - Image reproduction output device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying apparatus having an automatic document exposure (hereinafter referred to as AE) apparatus. Conventionally, this type of device performs preliminary scanning for AE, detects the lightness and darkness of the original document, and controls the original document exposure lamp and the process means for image formation based on the detected value so that the proper density is obtained. .

Further, in a copying machine capable of changing the magnification of an original image and copying the same, for example, as described in JP-A-56-138747, the scanning speed of the optical system is prevented from becoming too high during reduction copying. Therefore, a copying machine having a structure in which the driving speed of the photoconductor is slowed is considered.

However, if the same density detection method is executed regardless of the image forming magnification in a copying machine in which the driving speed of the photoconductor is variable, the density of the image actually formed becomes incorrect, and the density of the pre-scan is reduced. There is the inconvenience that it takes time to switch the state of the apparatus to the actual scanning for image formation.

The present invention has been made in view of the above points, and provides an image reproducing apparatus capable of accurately measuring the density of an original and obtaining an image of an appropriate density regardless of the driving speed of the photoconductor during preliminary scanning of the original. That is the purpose.

That is, the present invention comprises an exposure scanning means for exposing and scanning a document,
An image forming unit that forms a latent image of a document that has been exposed and scanned by the exposure scanning unit on the photoconductor and develops the latent image; and, if the image forming magnification is equal, drives the photoconductor at a first speed. Then
In the case of reduction, it corresponds to the driving means for driving the photoconductor at the second speed lower than the first speed, the measuring means for measuring the surface potential of the photoconductor, and the driving speed of the photoconductor. The potential of the latent image in a predetermined range of the original formed on the photosensitive member driven at the first speed or the second speed by prescanning the original with a constant light amount by the exposure scanning unit at the scanning speed A density detecting means for measuring by a measuring means, integrating the output of the measuring means, and detecting the density of the document based on the integration result, and an image forming after the preliminary scanning based on the output of the density detecting means. Control means for controlling the exposure scanning means or the image forming means during main scanning to adjust the density of the image developed by the image forming means, and the density detecting means drives the photoconductor. Speed is the second speed above The measuring time of the measuring means is set longer than the measuring time of the measuring means when the driving speed is the first speed, and the detected density of the density detecting means for the same document is concerned with the driving speed. The present invention provides an image reproduction output apparatus that changes the integration condition of the density detecting means depending on whether the driving speed is the first speed or the second speed so that the driving speed is the same.

FIG. 1 shows this embodiment.

Reference numeral 100 is a main body of the copying machine, and reference numeral 200 is an external additional device (ADF in this case) connected to the main body. The copier body and the ADF are connected by the signal shown in FIG.

The reference numeral 33 designates a photosensitive drum, which rotates in the clockwise direction of the arrow.
50 is a main motor, including 33, 44 fixing device, 41 transport section, 38 paper feed roller, etc., and 21 all drive including the optical system drive including original illumination lamp is performed by a chain (not shown). I am doing this.

Further, 31 is a high-voltage charger. As a result, the charge is charged on the 33 photosensitive drum. Then, after the electrostatic latent image is formed by being exposed at the point A, the developing roller in the developing device in 29
At 34, toner adheres and is visualized. Then, the toner image is transferred onto the transfer paper in the transfer charger 40. Prior to this, the cassette 37 feeds the paper feed roller 38 at a timing such that the front end of the toner image and the front end of the transfer paper coincide with each other.
Paper is fed by the rotation of, and the paper is sent out by the registration roller 39.

At this time, the exposure of the original is illuminated by the 21 original illumination lamp, and the optical system including 21 scans the original in the direction of the arrow and passes through the reflecting mirrors 24, 25, 27 and 28, and the lens 26.
33 An image is formed at point A on the photosensitive drum, and exposure is performed over the entire surface of the original. Reference numeral 48 is a registration sensor. The registration roller 39 starts to rotate by this sensor so that the leading ends of the images are aligned with each other as described above. 22 and 23
Is an inversion sensor, and 23B is a home position B for preliminary scanning at the time of AE measurement, and at the same time, a cassette 37
Is also a small size (for example, B5, A4 size, etc.) optical system inversion position. On the other hand, 23 is a large size (for example, A3 size) optical system inversion position.

After the transfer, the photosensitive drum 33 is cleaned by the cleaner brush 36 in the cleaner portion 35 and then electrostatically cleaned by the eraser 32 to prepare for the next charging. On the other hand, the transfer paper on which the toner image has been transferred is separated from the photosensitive drum and conveyed by the paper conveyance unit 41 toward the fixing device.

At this time, the suction fan 42 continues to convey while being attracted downward. The copy paper, which is fixed by the fixing roller 44 and is finally completed, is ejected to the paper ejection tray 47 by the paper ejection roller 46. Reference numeral 45 is a web motor for winding a web for cleaning the fixing roller 44. Reference numeral 43 is a power transformer, and 30 is an exhaust heat fan that releases the heat of the 21 lighting lamps.

Next, the name and operation of each part on the ADF side will be described. First, when the operator places a document on the document tray 1, the AF document sensor 10 senses the document. Here, AF is one of the mechanisms that compose the ADF, which is equivalent to 300 in FIG. 1 and which fulfills one function together with 200.
00 is called DF, and AF + DF is called one system function, that is, ADF. AF is the abbreviation for Auto Feeder, and DF is the abbreviation for Document Feeder. When a document is placed in such a mechanism and the ADF start switch D in the operation display section is turned on, the pick-up roller 2 is lowered. After a lapse of a predetermined time, the AF motor (not shown) rotates and the uppermost original among the stacked originals starts to be conveyed. The AF timing sensor 11 is located at the leading edge of the document conveyed between the separation belts 3 and 4 that move in the direction of the arrow
When detected by, the pickup roller 2 moves upward. Then, the document is conveyed from the AF section 300 to the DF section 200. When the leading edge of the document is detected by the DF document sensor 12, the separation belt 4 is pushed down. Also, the operation of the separation belts 3 and 4 is stopped. Then, after a predetermined time has elapsed, the operation of the AF section is stopped.

In the DF section, when the DF document sensor 12 detects the leading edge of the document, the pressing roller 5 moves downward and presses the document. Then, the DF motor (not shown) starts rotating, and the DF section pressing roller 5, the conveying roller 6, the belt driving roller 15, the turn roller 16,
The discharge roller 8 rotates. As a result, the document starts to be conveyed at a faster speed than the AF section.

When the document passes the conveyance roller 6, the leading edge of the document is detected by the entrance sensor 13, and from this point, the clock pulse generated by the clock generator (not shown) synchronized with the DF motor is counted. Then, the pressing roller 5 moves upward. Next, the original is full-face belt 7 and original platen glass 20.
It enters the space and is conveyed by the entire belt 7.

When the entrance sensor 13 detects the trailing edge of the document, if the AF unit has a document to be fed next, the feeding of the next document is started as described above. This document stands by at the position of the DF document sensor 12. When the number of pulses generated from the clock generator reaches a specified value, the DF motor is stopped and a COPY START signal is sent to the copying machine body.

Incidentally, 49 is a potential sensor for measuring the surface potential of the photosensitive drum 33. Generally, the surface potential of the photosensitive drum is as shown in FIG. The surface potential of the drum is charged to V ₀ by the corona discharge. Then, the dark decay occurs until the exposure point A. At the exposure point A, the document illumination lamp 21 irradiates the document and the light according to the document density generated by the reflection is exposed. At this time, when the original is light, the amount of reflected light is large, and accordingly, the surface potential drops to the vicinity of VL shown in FIG.

On the other hand, when the original is dark, the amount of reflected light is small and the surface potential does not drop so much. Therefore, by reading this surface potential, it is possible to determine the shading of the document. Next, a circuit diagram from the measurement of the drum surface potential to the control of the light amount of the document illumination lamp is shown in FIG. Fifth
In Fig.-1, Q525 is an operational amplifier, and R501 and C501
Together with it, it constitutes an integrator. As a result, the drum surface potential is integrated for a certain period of time, a curve as shown in FIG. 4 is obtained by this value, and a lamp control voltage VLiNT for controlling the light amount of the document illumination lamp is created. Also, 530 is a transistor and 523 is a FET. These constitute a gate circuit, and the signal (e) shown in FIG. 6 is input. or,
531 is a transistor and 524 is a FET. These are C
It constitutes a reset circuit for resetting the charge charged to 501. The signal (f) shown in FIG. 6 is input here. AE used in this example as shown in FIG.
The device has two limiter functions, VLiNTmax and VLiNTmin. The operational amplifier 52 realizes this function.
6 Constant current circuits 527, 528, limiter 529, buffer 532 are elements. Drum surface potential output V ₁ was when the drum surface potential output V ₁ was a 10v next pale document when a dark document as shown in the table 5-2 diagram the 12v. Furthermore, the corresponding integrator output V ₂ is 16v for dark and 12v for light.
Becomes Next, the gain of the differential amplifier 526 is A = 2. If the lightness of the original is darker than the predetermined darkness,
When V ₂ = 16v, the output of 526 is 4v, the current i5 flowing through the constant current circuit is 0, and VLiNT = 16v, so that the proper exposure amount can be obtained by skipping the document (moving in the direction of fading). , Turn on the document illumination lamp.

On the contrary, when the original is light, for example, the drum surface potential output V ₁
Is 11v or more and 12v shown in the table of FIG. 5-2, the output of the differential amplifier 526 becomes 8v and is limited to 8v by the limiter 529. The V ₄ output is 8v. Therefore, VLiNT = 1
It is 0v. Furthermore, when the drum surface potential is between 10v and 11v, it is shown in the graph with the slope of the following equation. This is shown in FIG.

VLiNT = 16− (R504 × R505) / (V ₄ −4) (Equation 1) As shown above, the limiter is provided at the upper and lower limits to make the copied image darker than necessary, or It is possible to prevent lightening.

By the way, as will be described later, in this embodiment, the rotation speed of the photosensitive drum 33 changes. This is because the rotation speed of the main motor 50 is divided into two types, high-speed rotation and low-speed rotation. When copying at the same size, select high-speed rotation (rotation speed of photoconductor 340 mm / sec), Also reduced, for example 86%
Or 70%, select a constant low speed rotation (photoconductor rotation speed 238 mm / sec) regardless of the reduction ratio. In order to change the time constant of the integrator at this time, the circuit shown by the dotted line in FIG. 5-1 is provided, and a resistor is connected in parallel with R501.

Also, in order to always read the shaded area on the document surface shown in FIG. 8 due to the change in process speed, the AE measurement time, t2
Must be variable. Details will be described later.

As described above, the light and shade of the specific portion of the document shown in FIG. 8 is read, and the light amount of the document illumination lamp during image formation is controlled.

Further, as described above, the limiters are provided at the upper limit and the lower limit, but three adjustment points are provided in order to correspond to various kinds of documents as much as possible.

In FIG. 5, the first method is a level shift for 526. This is done by VR101. Second
Is the gradient of the light and shade control. This is done by R505 (which is considered a variable resistor as VR102).
It is a curve shown in Formula (1). The third method is VR103 in Limiter 529. This is graphically
This corresponds to a point in FIG. The adjustment method will be described below with reference to FIG. 4. The points are determined by the above-described first method. Next, the slope in the second method is determined. Next, the points are determined and the adjustment is completed by the third method.

In addition, 109 shown in FIG.
Is a high-voltage charger. This is because the surface potential of the drum was measured by the 49 sensor before measuring the density of the original, and 10
9 Control via high voltage transformer. So-called potential control is executed. This is because after the main power switch of the device is turned on, the drum is rotated for a predetermined time during the waiting time or the standby time before the copy key is turned on.
, The surface potential is converged to a constant potential by the sensor, and the device is set to the standard state. in this case,
A standard white plate is provided near the home position 22A (Fig. 1), the lamp 21 is turned on by the level 5 of the slide lever 907, and the sensor 49 detects the potential of the bright latent image created by the reflected light from the white plate at that time. It is possible to detect and control the light amount of the lamp 21 to converge the bright potential to a predetermined value. By measuring with the lamp 21 turned off and controlling the charger 31, the dark part potential can be stabilized.

In Fig. 6, the lamp light intensity during AE measurement is the concentration selection lever.
Although it corresponds to the specific light quantity at the position 5 in 907, the light quantity near the front and back is also possible.

Next, the operation timing chart and flow chart of each unit in the present embodiment are shown in FIG. 6, FIG. 7-1 to FIG. 7-5, and FIG. The order of the description is the order of the movement of the ADF in the case where the operator uses the ADF to copy two originals, and the copy sequence of the main body following the movement.

As described above, the operator sets the document on the document device tray 1 in the AF section of the ADF and then presses the ADF start switch to bring the ADF into the operating state. Then, the originals are separated one by one from the upper side, and when the originals reach the treatment position by the DF section (point C in FIG. 1), the COPY START signal is sent from the ADF to the main body. This corresponds to step 701 in Fig. 7-1, and in the copying machine main body,
Upon receiving this COPY START signal, the copy operation is started.

First, reset the ADF START signal so that the ADF does not malfunction. In this state, the reset state remains until the end of the copy operation. Next, the optical system starts to move forward for AE measurement. At this time, the peak hold circuit of the AE measurement circuit shown in Fig. 5-1 is reset to prepare for AE measurement, and as shown in Fig. 6 (f). Generates an AE reset signal. This AE reset signal is generated before the copy operation starts, and when the continuous copy operation is interrupted due to the lack of toner or transfer paper during copying,
Since this reset circuit is set so as not to operate, the restart of copying in such a case has a sequence such that AE measurement is not executed. Now, as shown in step 702, the optical system that has started the forward movement continues to advance until it senses the home position B. When the home position B is sensed, the optical system changes from forward to backward, and the original illumination lamp 21 is turned on with standard brightness.

This state is shown in (h) and (i) of FIG. 6 of the time chart. The standard brightness does not change between AE measurements and is always constant. The home position B in this case is 22B in FIG.

When T1 has elapsed since the optical system started backward movement, AE
To start the measurement, (e) AE measurement signal shown in FIG. 6 is generated. This corresponds to step 703 in Figure 7-2.
Then, at step 704, A
E The measurement signal can be stopped. This is for measuring the shaded area shown in FIG. Further, + α in FIG. 8 indicates the exposure point A and the surface potential measurement point B shown in FIG.
This is because the deviation in distance to is corrected. By the way, the AE measurement signal is determined at time T1 and T2 after the backward movement of the optical system is started.However, when all the drive sources are obtained from the main motor 50 as in the present embodiment, the rotation speed of the main motor is In the case of a change, the backward speed of the optical system naturally changes. This will also affect the width of the AE measurement signal. For example, if there are two types of motor rotation speeds, high speed rotation and low speed rotation, and if it is desired to always read the document density in the shaded area shown in FIG. 8, the AE measurement time t2 is short during high speed motor rotation, and vice versa. It is necessary to set t2 longer when rotating at low speed. This is input to the "AE measurement" terminal of the AE measurement circuit shown in FIG. 5-1, but the judgment of high speed or low speed is made by software. At the time of reduction, the rotation speed is low. Here, the speed V ₁ of the surface of the photoconductor during high-speed rotation is
340 mm / sec, the surface speed V ₂ of the photoconductor at low speed rotation is 238 mm / sec.
sec, the backward speed υ ₁ of the optical system during high-speed rotation is 850 mm / sec, the backward speed ν ₂ of the optical system during low-speed rotation is 595 mm / sec, and the length a of the range for measuring the density of the document is 70 mm. Since the drive of the optical system and the drive of the photoconductor are performed from the main motor 50 as described above, the reverse speed of the optical system is proportional to the drive speed of the photoconductor. V ₁ / V ₂ = υ ₁ / υ ₂ ,
The backward speed of the optical system is constant at 595 mm / sec during reduction copying regardless of the reduction rate.

Since the copying apparatus in this embodiment performs slit exposure as in a normal copying apparatus, the length of the latent image in the density measuring range of the original formed on the photoconductor is not affected by the projection magnification of the lens. Instead, it changes according to the ratio between the backward speed of the optical system and the rotational speed of the photoconductor (if the speed is the same, the length of the measurement range and the length of the latent image are the same). Therefore, the length 1 ₁ of the latent image at the time of high speed rotation a · V ₁ / υ _1, i.e., a 28mm. Similarly, the latent image length 1 ₂ at the time of low speed rotation is a · V ₂ / υ ₂ , that is, 28 mm, and the length of the latent image becomes equal at the time of high speed rotation and at the time of low speed rotation.

The time required to measure the potential of the latent image on the photoconductor is obtained by dividing the length of the latent image by the drive speed of the photoconductor, so the measurement time t ₂₁ at high speed rotation is 1 ₁ / V ₁ , That is, 82.
It will be 4 msec. Similarly, the measurement time t ₂₂ at low speed rotation is 1 ₂ /
It becomes V ₂ , that is, 117.6 msec. That is, the potential measurement time is different between the low speed rotation and the high speed rotation. Step 70
In 5, it is judged whether the optical system in the backward movement reaches the home position A, and if it reaches the home position A, the VLiNT signal corresponding to the image density obtained by the AE measurement is determined. Then, the light amount of the original illumination lamp is determined, the light is turned on, and the optical system advances for exposing the original and forming an electrostatic latent image. At this time, the optical system switches from the density measurement-like speed to the image forming speed according to the copy magnification to perform forward scanning.
That is, if the magnification is the same, 340 mm / sec, which is the same as V _1, and 70% reduction is V ₂ ÷ 0.7 = 340 mm / sec, and 86% reduction is V ₂ ÷
0.86 = 277mm / sec. At this time, paper feeding is also performed. From step 706 onward, the sequence is the same as the normal copy copy sequence, but the reversal position changes depending on whether the 37-sheet cassette size shown in FIG. 1 is a large size or a small size. That is, in the case of the large size, the optical system changes from forward to reverse with the 23-inversion sensor, and in the small size, it is inverted by the 22B-inversion sensor.

The 22B inversion sensor is also a home position as described above. At step 707, it is checked whether the predetermined number of copies has been completed. If the predetermined number has been reached, an ADF START signal is sent to instruct the ADF to replace the original.

In response to this, in the ADF, the document feeding or discharging operation is started. In the present embodiment, as shown in FIG. 6, the number of copies is one for two originals, so in step 707, the ADF START signal is immediately generated. If the number of copies is set to multiple, the halogen lamp will be turned on in preparation for the next copy, but the lighting timing should be turned on early considering the rise time of the halogen lamp etc. become. However, the reversal sensor 22
Naturally, the time from when the halogen is turned on to when B and 23 are reversed is different. Therefore, in step 706, this problem can be solved by selecting the timer values T3 and T4 according to the paper cassette size.

At step 708, it is judged whether or not a predetermined number of sheets have been finished, and if not, a jump is performed to repeat the copy operation. If the number of copies reaches a predetermined number, the optical system starts to move forward to the home position B. Then, when it reaches the home position B, the advance of the optical system is stopped and the COPY START signal from the ADF is seen. (Step 709) If the COPY START signal arrives within T5 hours, it means that the document feeding / ejection is completed in the ADF, so the jump is performed so as to start the backward movement of the optical system for the AE measurement. On the other hand, in step 710, the predetermined time T5
If there is no COPY START signal from the ADF even after, the optical system backward movement is started in order to return the optical system in the home position B to the home position A. Then, after returning to the home position A, the backward movement of the optical system is stopped and a series of copy sequences is ended. When the measurement time is lengthened when the photoconductor rotates at a low speed, the dotted line circuit in FIG. 5-1 is connected to lengthen the time constant of the integrator. That is,
The dotted line circuit in Figure 5-1 is designed so that the time constant during low speed rotation is τ · V ₁ / V ₂ = 1.43τ, where τ is the time constant during high speed rotation. As a result, the amount of integration becomes equal between the normal size copy and the reduced size copy.
AE control can be executed accurately. This point can be applied to other copying modes in which the scanning speed and the drum speed are changed.
Further, the control target by the AE may be the developing bias voltage, and the measurement target may be a part of the original light. AE and some other embodiments of the present invention are also effective in an apparatus for reading an original image of an original, a copy, etc. with a CCD, converting it into an electric signal, and processing it for printing or transmission. .

When the time t ₂ is determined by the pulse generated in synchronization with the speed of the movement of the scanning system or the rotation of the drum, it can be determined by a predetermined number of counts (of pulses) regardless of the magnification. The same applies to t ₁ .

By the way, regarding the operation method, FIG. 9 shows an operation unit. 900 is the operation panel, 901 is the cassette size display,
902 is a manual feed display section, 903 and 905 are upper and lower selection keys, 90
4,906 is an upper and lower cassette selection display, 907 is a copy density lever, 908 AE selection key, 909 is a clear key, and 910 is a numeric keypad. 911 is a jam display, 912 is a 7-segment display, 913 is an interrupt display, 916 is an interrupt selection key, 917 is a stop key, 914 is a weight display lamp, and 918 is a power-saving selection key. Is.

Speaking of an interrupt, the normal usage is a function of stopping the operation currently being copied and executing an emergency copy when it is desired to make an emergency copy during continuous copying. However, regarding this operation method, if you do not use ADF and only copy the main body, there is no problem, but as described above, AD
When using F, inconvenience may occur in the following cases. For example, when copying multiple originals using the ADF, if a series of copies is not completed and there is a request for interrupt copy, and the 916 interrupt key is pressed, the copy sequence of the copier will be Stops and enters interrupt state. However, the copied originals are ejected and stacked on the original ejecting section 9 shown in FIG.
On the other hand, the uncopied original document remains on the original document tray 1. In this state, the emergency interrupt copy is executed, but in order to prevent the page order of the original document before the interrupt state from being disturbed, it is impossible to remove the uncopied original document left on the original document tray 1. . Therefore, it is better to prohibit the use of ADF in the interrupt status. In this embodiment, the use of ADF is prohibited when it is in the interrupt state,
The operation of the ADF start switch D shown in FIG. 1 is prohibited.

918 is a power saving selection key, and 919 is a power saving mode display section. Power saving mode is a normal fixing temperature setting, for example 180 ℃
Is a function for lowering the temperature and controlling the temperature at, for example, 150 ° C. to save power. Reference numeral 44 shown in FIG. 1 is a fixing roller of a system generally called a thermal fixing system.

As described above, when the power saving mode is selected, the temperature of the fixing roller 44 decreases from 180 ° C. to 150 ° C., for example. At the same time, the display section of the operation section shown in FIG. 9 is turned off except for the power saving selection display section 919. This contributes to power saving. However, the power saving selection key 918 is not always accepted. For example, the input of the power-saving selection key is prohibited during copying, and the input of the power-saving selection key is prohibited when a jam occurs, warm-up after turning on the power, or warm-up after canceling the power-saving mode selection. There is.

Therefore, the input of the power saving selection key is permitted only when the copying machine is in the standby state.

Further, reference numeral 918 denotes an alternate key, which is selected by pressing and released by pressing again.

Next, 908 is an AE selection key. Normally, the AE mode is selected with priority. For example, when the power is turned on, the AE mode is given priority. Further, 908 has a structure such that it can be displayed at the same time as a selection key. This AE selection key is also an alternate key like the power saving selection key described above. Also, the input of the AE selection key is prohibited when a jam occurs or when an error occurs during copying (error is abnormality detection of the copying machine, but detailed description is omitted). Further, during the prohibited copy, the optical system is switched from forward to reverse in the final paper copy of continuous copy, that is, permission is changed at so-called reversal. Therefore, when the ADF is in use, the (b) signal shown in Fig. 6 indicates that when the last sheet is reversed (in this case, one copy is made), the ADF is performing document feeding and discharging, and performing AE measurement. Therefore, it is allowed before the advance of the optical system for pre-scanning is started.

Reference numeral 902 denotes a manual feed display unit. The manual feed is a function to place a paper other than the transfer paper in the upper cassette 51 in FIG. 1 such as a postcard or a straw-sized paper by placing the postcard on the manual feed guide 54 and making a copy. Is. In that case, lower the manual feed lever 53 downward and
The transfer paper inside 51 is blocked by the upper paper feed roller from being fed. Reference numeral 55 denotes a manual feed detector, which detects when the manual feed lever 53 is pushed downward and the manual feed mode is selected. If the manual feed mode is selected, the manual feed indicator 902 in FIG. 9 lights up. For example, when the lower cassette is selected, naturally the lower cassette selection display area 906
Is turned on, but even in this case, when the manual feed lever 53 selects manual feed, the 906 lower selection display is automatically switched to the 904 upper selection display, and at the same time, the manual feed display section 902 is turned on. Of course, after switching to the upper row, key input of the upper / lower row selection keys 903 and 905 is permitted. When the 53 manual feed lever is selected, the 902 manual feed display section is displayed as described above, and at the same time, the copy number display on the 912 7-segment display section is forcibly displayed as "1".

This is because one manual copy is in principle.
In addition, when the manual feed mode is selected, the numeric keypad 910
Is prohibited from inputting. When the lever 53 is switched to the hand side, the value is switched to 1 regardless of the number of indications. When the lever is returned, the numeric keypad can be input. AE is possible regardless of hand selection and interrupt copy selection.

The ADF start key is prohibited until the interrupt signal is released by turning the stop key on after the interrupt key is turned on or until the interrupt copy is completed.However, when the interrupt key during copying without ADF is turned on, the copy of the set number is completed. The copy was interrupted before, the ADF start key was accepted, and the interrupt copy of the ADF can be executed. In this case, when the preset number of interrupts is completed, the normal control that automatically returns to the copy mode before interruption is prohibited until the original is lost in the feeding section, and when it is lost, it automatically returns to the previous copy mode. Then, the remaining number of copies in the previous mode is displayed, and if the previous mode is AE, AE is displayed. By the way, when the previous copy is being executed in non-AE mode and the interrupt copy key is turned on, even if the copy number display is set to 1 (automatically), it is not set to the AE mode of AE display. Therefore, it is easy to operate. All keys including the AE key are not prohibited without paper.

The warm-up time mentioned above is the wait time until the fixing heater reaches the copy-enabling temperature, and the standby state means the machine state at least before the start of drum rotation and after the stop of drum rotation. When the power-saving key is turned on, all but the power supply of the temperature control circuit of the fixing heater and the power supply of the microcomputer described later are cut off.

In FIG. 6, the drum is pre-cleaned by the cleaner and is pre-exposed by the lamp 32 to stabilize the drum until the scanning of the first original is started.

During this time, the transfer charger 40 is in the inoperative state, and therefore fatigue of the drum can be prevented. Each charger is operated after the start of scanning the original until the scanning of the final original is finished, but thereafter, it is inoperative until the start of AE measurement, and the drum 32 is made uniform in potential by the lamp 32. Also, the drum stops after being left after being cleaned. After a further 2 hours, the main power switch is turned off and only the microcomputer is powered on. The same is true even if left for 2 hours after the power saving switch is turned on. If left unattended during a jam, return to AE mode and copy number non-AE, 1 is prohibited, but after 2 hours, the power is turned off as described above and the display etc. disappears. Returning to non-AE, 1 is the control that is performed after a fixed time (30 seconds) has elapsed after the main motor was stopped. Note that this return control can also be performed in synchronization with the drum stop by the main motor.

When the 915 copy key shown in FIG. 9 is pressed,
Enter the copy sequence. A certain amount of time is required from the start of the preliminary scanning by the optical system to the start of the actual exposure. If you want to stop the copy operation during this time, you can press the 917 Stop key to stop the copy operation. That is, in steps 701, 702, 703, 704, and 705 shown in FIGS. 7-1 and 7-2, the copying operation can be stopped until the paper feeding is started. Since it gets in, the copy operation proceeds. In this case, copying is performed by AE, but if it can be stopped, the optical system (scanning system) is set to the home position.
Stop at position 22B and wait. If left for a predetermined time, it returns to the home position 22A as described above. In synchronization with the return of 22A, the AE display disappears and the camera enters non-AE mode. If the AE is canceled during the waiting period, the AE display disappears, but the scanning system remains at the 22B position, and the copy key is turned on to return to 22A later. Do this while the drum is rotating for pre-cleaning and pre-exposure.

The operation timing of the copying machine shown in FIG. 1 has been described above, and the control unit that operates these loads will be described. FIG. 10 is a block diagram of the control unit. 102
Is a micro computer. The operation of 102 is basically as shown in FIGS. 7-1 to 7-5.
The timing chart for AE measurement is shown in FIG. In FIG. 10, 101 is a control board. 101 There is the above-mentioned microcomputer on the board, and as other input protection
There are 103 buffers or 104 and 107 as drivers. Ten
5 is a temperature control circuit. As described above, this is a circuit for controlling the temperature of the fixing roller 44, and 57 is a roller heater. 533 is a driver for driving the roller heater. 116 is a power plug. 115 is a power switch, 11
By inputting 5, the copier enters the wait time. This is because copying cannot be executed until the 44 fixing roller reaches a predetermined temperature. At this time, it is generally called weight up time, and the 914 weight lamp shown in FIG. 9 is turned on to notify this. When the power switch 115 is turned on, the power is supplied to the power circuit 114 through the 43 power transformer. Then, 24 vDC and 5 vDC are supplied to each load and the control board 101. Reference numeral 113 is a DC load, 112 is an AC load, and 111 is an AC driver for driving the load. Also, 106 is an illumination lamp light quantity control unit 108 including FIG. 5 which calculates the measurement result of the drum surface potential and controls the corona current of the high voltage transformer. This is called a potential control circuit.

Naturally, including the AE measurement, it is sent to the 106 illumination lamp light quantity control unit.

As described above, according to the present invention, in the image reproduction output device in which the driving speed of the photoconductor changes in accordance with the image forming magnification from among the kinds of speeds which are smaller than the kind of the image forming magnification capable of forming an image, Pre-scan with a constant amount of light to measure the potential of the latent image formed on the photoconductor driven at a speed according to the image forming magnification, calculate the measurement output, and detect the density of the document based on the calculation result. At this time, by changing the potential measurement time according to the drive speed of the photoconductor and changing the calculation method according to the drive speed so that the calculation results of the measurement output of the same document are the same regardless of the drive speed. Even in a copying machine in which the driving speed of the photoconductor changes during the preliminary scanning of the document depending on the image forming magnification, the document density can be accurately detected, and thus an image having an appropriate density can be obtained.

Also during the preliminary scanning for density measurement, by changing the driving speed of the photoconductor in accordance with the image forming magnification, it is possible to smoothly shift to the main scanning after the preliminary scanning.

[Brief description of drawings]

FIG. 1 is a sectional view of a copying machine to which the present invention can be applied, FIG. 2 is an explanatory view of control signals, FIGS. 3 and 4 are potential characteristic diagrams, and FIG.
E control circuit diagram, FIG. 5-2 is its output explanatory diagram, FIG. 6 is an operation time chart, FIGS. 7-1 to 7-5 are control flow charts, and FIG. 8 is a shade measurement area diagram. , FIG. 9 is a plan view of the operating portion, and FIG. 10 is a control block diagram.
Is a photosensitive drum, 21 is a document illumination lamp, 49 is a potential sensor,
Reference numeral 200 is an ADF and 106 is a lamp control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideki Adachi, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-58-172654 (JP, A) JP-A-59 -136728 (JP, A)

Claims (1)

[Claims] 1. An exposure scanning means for exposing and scanning an original, an image forming means for forming a latent image of the original exposed and scanned by the exposure scanning means on a photoconductor, and developing the latent image, and an image forming magnification Driving means for driving the photoconductor at a first speed in the case of equal magnification, and driving the photoconductor at a second speed lower than the first speed for reduction, and a surface of the photoconductor. Measuring means for measuring the electric potential, and photosensitive being driven at the first speed or the second speed by prescanning the document with a constant light amount by the exposure scanning means at a scanning speed corresponding to the driving speed of the photoconductor. Density detecting means for measuring the potential of the latent image of a document formed on the body in a predetermined range by the measuring means, integrating the output of the measuring means, and detecting the density of the document based on the integration result, After the preliminary scanning based on the output of the density detecting means Control means for controlling the exposure scanning means or the image forming means at the time of main scanning for image formation to adjust the density of the image developed by the image forming means, and the density detecting means When the driving speed of the photoconductor is the second speed, the measuring time of the measuring means is set longer than the measuring time of the measuring means when the driving speed is the first speed, and the same document is read. The integration condition by the density detecting means is changed according to whether the driving speed is the first speed or the second speed so that the density detected by the density detecting means is equal regardless of the driving speed. Image reproduction output device characterized by.