JPS6356539B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a transfer material feeding control device in an image forming apparatus having a variable magnification function. A feeding control device in a transfer type electrophotographic copying machine will be explained below as an example. Conventionally, in order to align the leading edge of the image formed on the photoconductor through exposure and development with the leading edge of the transfer paper, a predetermined rotational position of the photoconductor is detected and a feeding roller is operated to transfer the transfer material to the transfer station. It was something to send. However, since the start of the optical system or document table that moves back and forth to scan the photoreceptor for exposure is not always constant, the latent image is not necessarily formed at a fixed position on the photoreceptor. The disadvantage was that the leading edge of the image was shifted. In order to solve this problem, there is a system that detects the specific position of the optical system or the moving path of the document table to operate the feeding roller, but in this case, the feeding timing is determined by the reciprocating movement of the optical system or the document table. During this period, there were restrictions. Therefore, it could not be applied to a copying machine that transfers images independently of exposure scanning. In addition, in a copying machine that can change the copy magnification,
The time relationship between the specific position detection timing of reciprocating movement and the feeding timing differs depending on the magnification, and the feeding timing cannot be uniformly determined from the detection timing. Further, even in a case where the length of the feeding path differs depending on each paper feeding section in a copying machine having a plurality of paper feeding sections, the feeding timing cannot be uniformly determined from the detection timing. The present invention aims to eliminate the above-mentioned drawbacks, namely, a scanning means 14 for exposing and scanning an original.
to 16, and an image forming means 1 for repeatedly forming an image corresponding to the document scanned by the scanning means on the recording medium for one scan of the scanning means.
3, 24, etc., means 33, 35, 43 for repeatedly feeding the transfer material to the recording medium, means 130-1 to 130-3 for setting the image forming magnification, and means 130-1 to 130-3 for setting the image forming magnification according to the magnification set by the setting means. The timing for operating the feeding means so that the leading edge of the image on the recording body and the leading edge of the transfer material are in a predetermined positional relationship is determined by determining the time from the reference time until the scanning means reaches a predetermined position. and means (CPU) for repeatedly controlling the feeding timing of the feeding means independently of the operation of the scanning means based on the storage signal of the storage means. It is provided by. Incidentally, when image exposure is carried out while the original (sheet) itself is being transported, it is also possible to set the memory by detecting the transporting position of the original itself. The position detection can be performed by operating a micro switch, a photoelectric element, or a Hall element provided on the moving path using a cam, a light emitter, or a magnet provided on the document table or optical system. The position of the original itself can be detected by activating the above-mentioned microswitch on the original, but by detecting the reflected light from the light emitter provided on the travel path. Examples will be described below with reference to the drawings. FIG. 1 is a sectional view of a screen type copying apparatus to which the control device of the present invention can be applied. In the figure, 11 indicates a housing surrounding the device,
A manuscript such as a literature or a document is placed on a manuscript table 12 made of a transparent member such as glass on the upper part of the housing 11. This document mounting table 12 is of a fixed type, and image irradiation onto a screen drum 13, which will be described later, is performed by partially moving an optical means. This optical means is already well known, and the first mirror 14 and document illumination lamp 15 move at a speed V over the entire distance of the placement table 12 from the solid line position to the leftmost chain line position. On the other hand, at the same time as the first mirror 14 moves to scan the mounting table 12, the second mirror 16 moves at a speed of V/2 from the solid line position to the leftmost chain line position. The original image obtained by the scanning of the first and second mirrors 14 and 16 is irradiated onto the screen drum 13 whose circumferential speed is V via a lens system 17 having an aperture mechanism and a fixed mirror 18. Ru. The screen drum 13 is made of a mesh drum in which a photoconductive layer is provided on a conductive layer, and a transparent insulating layer is further provided on the photoconductive layer. It's like that. The drum 13 rotates in the direction of arrow F, and a latent image forming means is arranged near the drum 13 along the direction of rotation of the screen drum 13. That is, 20 is a corona discharger which is a primary voltage applying means, and charges the rotating screen drum 13 to a sufficient voltage. Reference numeral 21 denotes a corona discharger serving as a secondary voltage applying means, which forms a primary electrostatic latent image by irradiating the original image while eliminating the charge on the screen drum 13 caused by the discharger 20. For this reason, the structure of the discharger 21 is such that the shield plate on the back side is optically open. Reference numeral 22 denotes a lamp for illuminating the entire surface of the screen drum 13, which uniformly irradiates the screen drum 13 with light to rapidly increase the electrostatic contrast of the primary electrostatic latent image. By the above means, a primary electrostatic latent image with high electrostatic contrast is formed on the screen drum 13. The primary electrostatic latent image thus formed on the screen drum 13 is formed as a secondary electrostatic latent image on the insulating drum 24 which rotates in the direction of arrow M by the modulating corona discharger 23. The insulating drum 24 is a conductive support 25 coated with an insulating layer 26, and by applying a voltage between the conductive support 25 and the conductive member of the screen drum 13, the modulated corona ions are transferred to the insulating layer 26.
6 to form the secondary electrostatic latent image. The secondary electrostatic latent image formed on the insulating layer 24 as described above becomes a toner image developed by a known liquid type or dry type developer (developing means) 27. The toner image is then transferred to a transfer location 28.
Then, the toner image is transferred onto a transfer material (sheet of paper) 29 that has been conveyed in synchronization with the toner image. The insulating drum 24 that has undergone the transfer process is then treated with a cleaner (cleaning means) 30 using a known blade or brush.
The remaining toner on the insulating layer 26 is removed at step 31, and the surface potential is made uniform by corona discharger 31 in preparation for the next copying process. The transfer material 29 to be conveyed to the transfer position 28 is loaded in a first cassette 32 and a second cassette 42, and is moved by delivery rollers 33 and 43, respectively.
and separated one by one by separation claws 34, 44,
The toner image is conveyed by the register roller 35 in accordance with the position of the toner image. Reference numeral 36 denotes a corona discharger for transfer, which is a discharger for applying a bias voltage to the transfer material 29 when transferring a toner image. After the transfer, the transfer material 29 is separated from the insulating drum 24 by a separation belt (not shown), and reaches the fixing device 38.
The toner image is fixed by the fixing roller 39 and conveyed by the conveyor belt 40 to a storage tray 41 for the completed transfer material. In the above-mentioned copying apparatus, once a primary electrostatic latent image is formed on the screen drum 13, a secondary electrostatic latent image is formed from this primary electrostatic latent image. There is no need to scan the original again when making a copy. Therefore, when making multiple copies, it is only necessary to operate the steps after the formation of the secondary electrostatic latent image. Therefore, in this step, the rotational speed of the screen drum 13 is set to be lower than that during the formation of the first latent image, for example. By increasing the speed by three times, the copying speed can be increased. FIG. 2 shows the operating section and display panel of the apparatus shown in FIG. SW in the figure is the process load of the copying machine, the main switch for turning on the power to the control circuit, 12
1 is a copy start key, 122 is a copy number setting key, 123-1 is a set number display, 123-
2 is the copy completion number indicator, each digit has 7 segments.
Displayed by LED. Reference numerals 126 and 127 indicate upper and lower paper feed cassette selection keys, which are illuminated to display selection when the key is turned on, and the paper sizes in the upper and lower cassettes are both displayed by 132. Keys 128-1 to 128-3 are used to select shades of light and dark, medium, and light.When the keys are turned on, the keys themselves light up to indicate this. 129
is a stop key to interrupt the copy operation,
Keys 130-1 to 130-3 are used to specify magnification, and each is set to 1x, 0.76x (hereinafter referred to as reduction (1)), and 0.65x (hereinafter referred to as reduction (2)), and the corresponding part of the display 131 is pressed. Light. The lower cassette 32 can store 2,000 to 3,000 sheets of paper, and the upper cassette 42 can store 500 to 1,000 sheets. FIG. 3 is a schematic diagram extracted from FIG. 1, showing only the portion necessary for registering the copy paper during transfer. A Hall IC for detecting the stop position (hereinafter referred to as the optical system home position) of the optical system (hereinafter referred to as the optical system home position) outputs an optical system home position signal OHP using a magnet provided in the optical system. Reference numeral 45 is a Hall IC installed in the document table movement path to detect the document table movement position (hereinafter referred to as the optical system registration position) in order to determine the feeding timing of the copy paper 29. The optical system resist position signal ORGP is output by passing through. A Hall IC 46 detects the final forward position of the optical system (hereinafter referred to as the reversal position), and outputs an optical system reversal position signal OBP. 47 is the home position of the screen drum 13 (hereinafter referred to as drum home position)
Screen drum 1 with Hall IC to detect
It is operated by a magnet provided at the reference position P of No. 3. 50 is a clock plate with a slit 50';
A photo interrupter 51 consisting of a light emitting diode and a photo transistor generates a clock pulse CP. One clock pulse CP is generated every time the screen drum rotates 1 degree. CL4 is a clutch (hereinafter referred to as a register clutch) for applying a rotational driving force to the register roller 35 in synchronization with the screen drum 13, CL3A is a lower sheet feeding clutch for applying driving force to the sheet feeding roller 33 of the lower cassette 32, and CL3B is a clutch for applying a driving force to the sheet feeding roller 33 of the lower cassette 32. Upper cassette 42
A is the upper stage paper feed clutch for applying driving force to the paper feed roller 43 of the screen drum 13. A modulation position where ions are modulated to form a secondary latent image on the insulating drum 24, C is a transfer position where the leading edge of the powder image on the insulating drum 24 and the leading edge of the copy paper 29 come into contact, and D is the position of the upper and lower rollers of the register roller 35. Indicates the stop position where the copy paper temporarily stops at the contact point. To is the time for the optical system to move from its home position 44 to the registration position 45;
To differs depending on the case, and is shown as To ₁ , To ₂ , and To ₃ .
T ₁ is screen drum 13 P is home position 4
7 until the optical system reaches the Hall IC ₄₅ at _the optical system resist _position . Indicated by ₁₃ . T ₂ is the time it takes for the copy paper to move from the stop position D of the copy paper on the register roller 35 to the transfer position C on the insulated drum 24 . T ₄ indicates the time from when the lower paper feed roller 33 starts rotating until the copy paper 29 reaches the stop position D, and T ₃ indicates the time from when the upper paper feed roller 43 starts rotating until the copy paper 29 reaches the stop position D. Since the length of the paper feed path is different between the lower stage and the upper stage, T ₃ and T ₄ are different from each other. As shown in FIGS. 3 and 4, the position of the lens system 17 and the initial position of the second mirror 16 are
The positions of the lens systems 17 are different depending on the reduction magnification (1) and reduction magnification (2), respectively.
7-3, and the initial position of the second mirror 16 is set to 16.
-1, 16-2, 16-3. Note that the initial position of the first mirror 14 remains unchanged. Therefore, the first mirror 14 and the second
The position of the mirror 16 differs depending on whether it is the same magnification, reduction (1), or reduction (2). Therefore, at the same magnification, when the first mirror 14 is detected by the Hall IC 45 (the first mirror 14 is at the position 14-1 in FIG. 4), the generatrix of the reflected light from the leading edge of the document 49 and the generatrix of the optical path are matches, but
At the time of reduction (1), the ORGP signal is detected after a time α after the generatrix of the reflected light and the generatrix of the optical path coincide (the first mirror 14 is at the position 14-2 in FIG. 4), and the reduction (2) )
At this time, the signal ORGP is detected after a time β of the first mirror 14 from the position 14-3 in FIG. Accordingly
The relationship between T ₁₁ , T ₁₂ , and T ₁₃ can be expressed as follows. T ₁₁ + α = T ₁₂ , T ₁₃ = T ₁₁ + β Here, if the registration roller 35 is driven uniformly with a predetermined delay time with respect to the registration position signal ORGP, the following results will be obtained: equal magnification, reduction (1), reduction (2) As a result, the leading edge of the image on the insulating drum and the leading edge of the copy paper 29 no longer match. The present invention eliminates such unreasonableness and furthermore uses a Hall IC4 for resist position detection.
The position of No. 5 is not moved according to the magnification. That is, since the time T ₁ was measured and stored in a RAM which will be described later, the time T ₁ was stored in order to determine the timing for driving the paper feed rollers 33 and 34.
This process subtracts time α and β according to the copying magnification from . In other words, as shown in the flowchart of Figure 5,
The screen drum 13 determines the timing for driving the paper feed clutch CL3 and the register clutch CL4.
It is determined based on the drum home position signal DHP of the rotation. When copying at the same size, 3rd rotation DHP
When the time obtained by subtracting the time _T4 from the time _T11 has elapsed, the lower paper feed clutch CL3 is driven;
When _T11 hours have elapsed since the third rotation of the DHP, the paper feed clutch CL3 is turned off and the registration clutch CL4 is driven. In addition, at the time of reduction (1), the lower paper feed clutch CL3A is driven after the time equal to the time _T12 minus the time _T4 and the correction time α has elapsed based on the DHP of the third rotation; When the time obtained by subtracting the correction time α from the time _T12 based on the DHP of the third rotation has elapsed, the paper feed clutch CL3 is turned off and the registration clutch CL4 is driven. Reduce(2)
In the case of , the clutch drive control is similarly performed at the timing after subtracting the correction time β. Repeat this process if you want to make multiple copies. Although we have explained the case where the lower cassette is used, when the upper cassette is used, the time it takes to drive the paper feed clutch is
It becomes T ₃ . As mentioned above, depending on the copying magnification, the feeding clutch,
Since the timing for operating the feeding means such as a registration clutch is set in advance, the set timing is memorized and the feeding means is repeatedly operated, the specific position detection means outputs a registration position signal according to the magnification. The leading edge of the image and the leading edge of the transfer paper can be aligned without moving the image, and the transfer can be controlled independently of exposure scanning. Furthermore, stable control is possible even when the length of the paper feeding path differs depending on the paper feeding section. The following description will be made based on the control flowcharts shown in FIGS. 6 to 8 and the timing chart shown in FIG. 9. (STEP 1) When the copy start button is pressed, the main motor M1, fuser motor M4, powder image transfer high voltage transformer HVT7, and insulating drum static elimination transformer HVT8
Turn on. (STEP 2) Check whether the optical system home position signal OHP is being output. If OHP is not being output, turn on the optical system reverse clutch CL2 to return the optical system to the home position. (STEP 3) Check whether the drum home position signal DHP is being output. Once the DHP is output, proceed to STEP 4. (STEP 4) Enter the ROM address specified by label TL1.
Working register WA (O) in RAM (Figure 11)
Store in. In other words, WA107 contains the drum clock pulse, which is executed by the subroutine SUBCP described later.
It contains the ROM address where the CP count number CPX is stored. Further resist flag
Set FLAGRG1, clear the previous registration counter RGCNT1, and turn on the primary charging high voltage transformer HVT1. (STEP 5) After counting 110 clock pulses CP in the subroutine SUBCP described later, the secondary static elimination high voltage transformer
Turn on HVT3, original exposure lamp L1, and full-surface exposure lamp L3. (STEP6, STEP7, STEP8) Here, select whether the copy magnification is 1x, reduced (1), or reduced.
(2) Determine whether the corresponding clutches CL1A, CL1
B and CL1C are each driven at predetermined timings. (STEP 9) When the screen drum 13 completes one rotation and the drum home position signal is output again, the primary charging high voltage transformer HVT1 is turned off. (STEP 10) Screen drum 2 with sublatin SUBCP
When the rotation reaches 115°, the secondary static elimination high voltage transformer
Turn off HVT3 and original exposure lamp L1. This completes the formation of the primary latent image on the screen drum 13. (STEP 11) When the screen drum 13 reaches the second rotation of 132 degrees, the main motor M1 is switched to high speed M1H and the optical system reverse clutch CL2 is turned on. The main motor rotates at three times the speed when forming the primary latent image. Therefore, the clock pulse CP is also output at three times the speed. (STEP 12) When the screen drum 13 reaches the second rotation of 165°, the entire surface exposure lamp L3 is turned off. (STEP 13) When the screen drum 13 reaches the second rotation of 200°, the developer motor M2 is turned on. (STEP 14) When the screen drum 13 reaches the second rotation of 250°, the latent image transfer high voltage transformer HVT 6 is turned on. (STEP 15) Here, the timing for driving the paper feed clutch and registration clutch is corrected according to the copying magnification. (STEP 16) Determine whether the paper feed cassette is in the upper or lower tier, and set the paper feed counter and registration counter depending on the tier. (STEP 17) Determine whether or not the screen drum 13 has reached the DHP of the third rotation. When the screen drum 13 reaches the third rotation, determine whether there is a stop command or whether there is paper in the selected paper feed section. do. If a stop command has been issued or there is no paper in the selected paper feed section, the process advances to step 1 and enters the stop routine. If there is no abnormality, proceed to STEP 18. (STEP 18) Transfer paper feed counter data and registration counter data in RAM to another address, and set paper feed flag FLAGPF and registration flag 2FLAGRG2. Additionally, specified by label TL3
ROM address to working register in RAM
Store in WA(O). (STEP 19) When the screen drum 13 reaches the third rotation of 110°, the resist clutch CL4 is turned off. (STEP 20, STEP 21) When the screen drum 13 reaches the third rotation of 120 degrees, brake clutch CL5 is turned on, and when it reaches 150 degrees, brake clutch CL5 is turned off. (STEP 22) Here, determine whether the number of completed copies and the set number are equal or not. If the number of completed copies has not yet reached the set number, return to STEP 17 and continue copying. If they are equal,
Proceed to the stop routine after STEP 23. (STEP 23) After completing the set number of copies, detect the drum home position signal DHP. For convenience, this DHP is assumed to be the 4th rotation DHP, but the actual copy setting number is M.
Then, it is the (M+3)th rotation. (STEP 24) Enter the ROM address specified by label TL4.
Store in working register WA(O) in RAM. (STEP25~STEP32) After the screen drum 13 reaches the fourth rotation, the developer motor M2 and resist clutch are closed at 110°.
Turn off CL4 (STEP 25), turn on brake clutch CL5 at 120° to stop the registration roller (STEP 26), turn off brake clutch CL5 at 150° (STEP 27), and turn on latent image transfer high voltage transformer HVT6 at 260°. Turn off (STEP 28). Furthermore,
At STEP 29 and 30, DHP at the 5th and 6th rotations is detected, and at 210° in the 6th rotation, the main motor high speed is switched to low speed (STEP 31), and at 260°, the main motor M1,
Turn off the powder image transfer high voltage transformer HVT7 and the insulating drum static elimination high voltage transformer HVT8. This completes the main routine and waits for the copy start signal to be output again. Next, the subroutine SUBCP shown in FIG. 8 will be explained. (STEP S1) Set the ROM data specified by the working register WA(O) in the RAM to the clock pulse counter CPX in the RAM. That is, the number of clock pulses to be counted in one subroutine SUBCP is stored in CPX. (STEP S2) Detect whether clock pulse CP is “1” or not, “1”
If so, set the RAM clock pulse flag FLAGCP. (STEP S3) Determine whether the optical system home position signal OHP is being output, and if OHP is being output, turn on the optical system reverse clutch CL2. (STEP S4) Determine whether the optical system back position signal OBP is being output, and turn off the optical system forward clutches CL1A, CL1B, and CL1C for equal magnification, reduction (1), and reduction (2). (STEP S5) Determine whether the optical system registration position signal ORGP is output. When ORGP is being output, the register flag 1 FLAGRG1 set in STEP 4 of the main routine is reset. (STEP S6) Determine whether the clock pulse flag FLAGCP is set, and if it is set, check whether the clock pulse flag FLAGCP is set or not.
Proceed to STEP-S7 and if it is not set,
Return to STEP-S2. (STEP S7) It is determined that the clock pulse CP is “0”, and if it is “1”, the process returns to STEP-S2, and when CP falls, it becomes “0”.
If the value (CPX) in the clock pulse counter CPX is reached, the value (CPX) in the clock pulse counter CPX is decremented by 1, the value is stored in CPX, and the flag FLAGCP is reset. In other words, STEP−S2,
Detect the fall of CP at S6 and S7 and reduce (CPX) by -1
are doing. (STEP S8) Register flag 1 FLAGRG1 when CP falls
is set. If it has been set, the registration counter 1 is incremented by 1. The registration flag 1 FLAGRG1 is set during the time _T1 , and the count number during that time is counted in the registration counter 1RG-CNT1.
In other words, the time _T1 is clocked and stored. (STEP S9) Determine whether the paper feed flag FLAGPE, which was set in STEP 18 of the main routine, is set.
If it has been set, proceed to STEP-S11.
If set, paper feed counter 2 in RAM
Subtract 1 from the value of PF-CNT2 (PF-CNT2). After that, it is determined whether (PF-CNT2) is 0 or not. If it is 0, proceed to STEP-S13; if it is not 0, proceed to STEP-S13.
Proceed to -S10 (STEP S10) Determine whether the paper feed section is the lower or upper step. If it is the lower step, turn on the lower paper feed clutch CL3A, if it is the upper step, turn on the upper paper feed clutch CL3B, and then set the paper feed flag.
Reset FLAGPF and proceed to STEP-S13. In other words, in STEP-S9 and S10, the main routine
3 of 13 screen drums determined by PTEP16
Measure the time (T ₁ - _{T 4} ) or (T ₁ - T ₃ ) from the DHP of the rotation to the paper feed, and turn on the paper feed clutch. (STEP S11) Determine whether or not the registration flag 2 FLAGRG2 is set, and if it is not set,
Proceed to STEP-S13 and if it is set
The value (RG-CNT2) of the registration counter 2RG-CNT2 in the RAM is decremented by 1. (STEP S12) Determine whether (RG-CNT2) is 0. If it is 0, turn off upper and lower paper feed clutches CL3A and B, turn on registration clutch CL4, and register clutch 2.
Reset FLAGR2. In other words, S11,S
12, the time from when the paper feed clutch is turned on to when the registration clutch is driven (for the upper stage, the time T
3. If it is the lower stage, time T4) and drive the resist clutch. (STEP S13) Determine whether the clock pulse counter CPX set in STEP-S1 has reached O. If it is not 0, continue counting clock pulses.
If it is 0, set the ROM address stored in WA (0) to 1
Take one step forward. Here, in the timing chart of FIG. 9, arrows indicate clock pulse counts performed in each subroutine SUBCP. The table below shows the relationship between the ROM address of the label that determines the CPX value in RAM, the stored data, and the drum angle.

[Table] Figure 10 shows a control circuit for executing the above process using a microcomputer. 1st
Figure 1 shows the RAM map. ROM in Figure 10
is a read-only memory in which the sequence contents of the key input data display operation and the copying process operation shown in Figures 6 to 8 are arranged in advance and stored in each address, and the contents can be retrieved each time an address is set. Use μPD454 manufactured by Manufacturer. RAM is a read/write memory that stores the number of copies and temporary control signals during process control, and a memory that stores one set of binary codes. One set is composed of a plurality of sets, and an arbitrary set is selected by an address designation signal, and data is written to or read from a plurality of flip-flops within the set. I/O ₁₀₀ to I/ON ₀₀ are input/output devices such as OHP,
It reads data input signals such as DHP signals, paper out signals, and key input signals, and outputs output signals that drive clutches, solenoids, motors, etc., all of which are sequentially driven by the sequence in ROM. The screen-type copying machine has been described above, but in a typical copying machine that exposes a photosensitive drum or magnetic drum to form an electrostatic or magnetic latent image, develops the latent image, and transfers the developed image to a transfer material. It is also possible to apply the invention for paper-to-image registration during transfer. In other words, this is effective when the registration roller is driven before the image exposure scan starts or after the scan ends. As described above, the present invention measures and stores the timing for operating the feeding means so that the leading edge of the transfer material and the leading edge of the image contributing to transfer are in a predetermined positional relationship according to the copying magnification, and based on the stored value. Since the operation of the feeding means is controlled, an image can be formed at a predetermined position on the transfer material no matter when the image formation period that contributes to transfer occurs, and even when transferring is performed repeatedly from one image, the image can always be formed at a predetermined position. can.

[Brief explanation of drawings]

Figure 1 is a sectional view of a screen type copying device, Figure 2
The figure shows the operation section of the copying machine in Figure 1, Figure 3 is a diagram for explaining the registration timing, Figure 4 is a diagram for explaining the optical system registration position, and Figure 5 is a diagram for explaining the registration timing. 6 to 8 are control flowcharts, FIG. 9 is a diagram showing the control timing of the copying machine of FIG. 1, FIG. 10 is a control circuit diagram, and FIG. FIG. 3 is a diagram showing a map of RAM in the control circuit of FIG. In the figure, 13 is a screen drum, 26 is an insulated drum, 33 is a lower paper feed roller, 43 is an upper paper feed roller, 35 is a registration roller, and 14 is a first paper feed roller.
Mirror, 16 is a second mirror, 17 is a lens system, 4
4 is a Hall IC that outputs an optical system home position signal OHP, 45 is a Hall IC that outputs an optical system registration position signal ORGP, 47 is a Hall IC that outputs a drum home position signal DHP, 50 is a clock board, and 51 is a clock pulse. Each photo interrupter that outputs CP is shown.

Claims (1)

[Scope of Claims] 1. A scanning means for exposing and scanning a document; and image formation for repeatedly forming an image corresponding to the document scanned by the scanning means on a recording medium for each scan of the scanning means. means for repeatedly feeding the transfer material to the recording medium; means for setting an image forming magnification; and according to the magnification set by the setting means,
The timing for operating the feeding means so that the leading edge of the image on the recording body and the leading edge of the transfer material are in a predetermined positional relationship is measured by the time from the reference timing until the scanning means reaches a predetermined position. and means for repeatedly controlling the feeding timing of the feeding means independently of the operation of the scanning means using the stored signal of the storage means.