JPH04338983A - Image forming device - Google Patents

Abstract

PURPOSE:To precisely make an original image match with an image formed on a transfer sheet when plural image formations are executed on one transfer sheet. CONSTITUTION:The image forming device is provided with an original feeding and electing control means, image forming means 110 and 120, detecting means 11-14 detecting the distortion of the transfer sheet by the fixing device of the image forming means, an instructing means, a transfer sheet refeeding means stacking the transfer sheet and sequentially feeding it to the image forming means so that the image is formed, again, on the image forming surface of a series of the transfer sheets on which the image is formed, or the back surface of the image forming surface, according to the instruction of the instructing means, and a correction control means changing the image forming magnification of the image forming means at prescribed timing, according to the distortion of the transfer sheet detected by the detecting means.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an image multiple times on a single sheet of transfer paper.

0002

2. Description of the Related Art In recent image forming apparatuses, such as copying machines, exposure light for an original image is irradiated onto a photoreceptor that has been uniformly charged in advance to form an electrostatic latent image, and the latent image is developed. After developing the image in a container and transferring the developed image to transfer paper,
Heat or pressure is applied to fix the toner image and form an image. As an additional function, such a copying machine has a double-sided copying or composite copying function of refeeding a transfer sheet on which an image has been formed and forming an image again on the image forming surface or the back side of the image forming surface.

0003

[Problem to be solved by the invention] In heat fixing,
Since the moisture contained in the transfer paper itself is evaporated by the heat of fixing, the transfer paper shrinks after fixing, and the degree of shrinkage differs depending on the type of transfer paper. It is known from experience that it takes about 15 to 20 minutes for the transfer paper to return to its original shape once it has shrunk.

[0004] In the case of normal one-sided copying, the above-mentioned development does not cause any problems. However, when performing double-sided copying with a copying machine equipped with a double-sided copying function, the toner image is transferred to the back side after the toner image has been transferred and fixed to the front side of the transfer paper. is in a contracted state, and an image transferred with the transfer paper in a contracted state will become larger by the amount of shrinkage of the transfer paper as time passes after copying is completed, resulting in a problem that the user will not be able to obtain the copy that he or she intended. . This applies not only to double-sided copying, but also to
The same applies to composite copying in which an image is once again composited onto a transfer sheet on which an image has been formed.

An object of the present invention is to accurately match an original image with an image formed on a transfer sheet.

[0006]

[Means for Solving the Problems] The image forming apparatus of the present invention has a document feed/discharge control means (200) that sequentially supplies documents one by one from a series of document sets to an exposure position, and controls discharge to a predetermined position after exposure is completed. , 450); A charge carrier (1
21) Form an electrostatic latent image on the surface, and transfer the latent image to a developing device (124).
image forming means (110, 120) that develops the image in ), transfers the developed image to transfer paper, and then fixes it in a fixing device (12C) to form an image on the transfer paper; Detection means (11, 12, 13, 14) for detecting distortion of the transfer paper caused by the fixing device (12C) of (110, 120);
Instruction means (7, 8, 10); Instruction means (7, 8, 10)
A transfer sheet that stacks transfer sheets to form an image again on the image forming surface or the back side of the image forming surface of a series of transfer sheets on which an image has been formed, and feeds the transfer sheets one after another to an image forming means according to instructions from the transfer sheet. Paper refeeding means (140); and detection means (
11, 12, 13, 14)), the image forming means (110, 120)
); correction control means (400) for changing the image forming magnification of the image formation magnification;
Equipped with Note that the symbols in parentheses are corresponding elements in the embodiment described later.

[0007]

[Operation] According to this, the detection means (11, 12, 13,
14) detects the distortion of the transfer paper caused by the fixing device (12C) of the image forming means (110, 120), and according to this distortion, the correction control means (400) adjusts the image forming means (110, 120) at a predetermined timing. ) to change the image formation magnification. Therefore, in double-sided copying or composite copying, two copies are printed on one sheet of transfer paper.
When performing image formation twice, if the distortion of the transfer paper during the first image formation is detected and the correction timing is set to change the image formation magnification during the second image formation according to the distortion, it is possible to It is possible to absorb the distortion of image formation caused by the distortion of the transfer paper in the second printing, and it is possible to perform stable image formation. Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0008]

[Embodiment 1] A copying apparatus as an example of the present invention includes a copying machine main body 100 shown in FIG. 1 and an automatic document feeder/discharge device (hereinafter referred to as RDH) 2 mounted on the upper part of the copying machine main body 100 shown in FIG.
Consists of 00. The copying machine main body 100 is an electrostatic transfer type copying device with a fixed original, and includes an optical system 110, an image forming system 120, a paper feeding system 130, a paper ejection system 140, and the like. The optical system 110 includes a contact glass 111, an exposure lamp 112 arranged below it, a first mirror 113A,
Second mirror 113B, third mirror 113C, fourth mirror 113D, fifth mirror 113E, sixth mirror 113F,
The image forming system 120 includes a lens 114, a dustproof glass 115, etc., and the image forming system 120 includes a photosensitive drum 121, a charger 122, an eraser 123, and a developing device 1 disposed around the photosensitive drum 121.
24, pre-transfer charger 126, separation charger 127
, a separation claw 128, a pre-cleaning charger (hereinafter referred to as PCC) 129, a cleaner 12A, and a conveyor belt 1 disposed downstream of the photosensitive drum 121.
2B, a fixing device 12C, etc. The paper feed system 130 is
It consists of a manual paper feed tray 131, a paper feed tray 131A, a call roller 132, a paper feed roller 133, a reversing roller 134 provided on the paper feed tray, a registration roller 135, a guide mylar 136, and various guides and intermediate rollers. Note that the manual paper feed tray 131 shares a calling roller 132, a paper feed roller 133, and a reversing roller 134 with the paper feed tray 131A. The paper ejection system 140 includes a contact/separation roller 142, a paper ejection roller 141, and the like.

When a document is set on the contact glass 111 and a start instruction is given, the paper feed clutch is turned on and the call roller of the paper feed table selected at that time feeds the transfer paper to the paper feed roller. The paper feed roller feeds the transfer paper toward the registration rollers 135. During this time, the optical system 110 scans the original on the contact glass 111, and the exposure lamp 1
12, the reflected light from the original is reflected by the first mirror 113A.
, second mirror 113B, third mirror 113C, lens 1
14, 4th mirror 113D, 5th mirror 113E, 6th mirror
The light is guided to the photosensitive surface of the photosensitive drum 121 via the mirror 113F and the dustproof glass 115. Note that when changing the magnification of the formed image, change the scanning speed and adjust the lens 11.
4, the positions of the fourth mirror 113D, and the fifth mirror 113E are moved.

The photosensitive drum 121 is rotating clockwise in the drawing, and its photosensitive surface is uniformly charged by a charging charger 122 and charged by an eraser 123 before receiving the reflected light from the optical system 110. A latent image area is formed by static electricity removal. Therefore, when this latent image area is irradiated with light reflected from the original, photoconduction occurs depending on the strength of the light, and an electrostatic latent image is formed. This electrostatic latent image is developed by a developing device 124, and becomes a toner image with toner attached thereto according to the density of the document. This toner image is transferred to the transfer paper fed out from the registration rollers 135, but in order to facilitate the transfer, the PTL 125 removes the charge before the transfer.

The transfer paper fed out by the registration rollers 135 is brought into close contact with the photosensitive surface of the photosensitive drum 121 by a guide mylar 136, and the toner image is transferred directly above the transfer charger 126. Immediately after this, the transfer paper is transferred to the separate charger 1.
27, but if the separation is insufficient, the separation claw 128 forcibly separates the photosensitive material. After the transfer paper is separated, residual toner is removed from the photosensitive surface of the photoconductor drum 121 by a cleaner 12A, and the transfer paper is sent to a fixing device 12C by a conveyor belt 12B. The fixing device 12C includes a fixing roller 12C1 and a pressure roller 12C.
2, the transfer paper on which the toner image has been transferred is heated (approximately 185° C.) while applying pressure to fix the toner image.

The transfer paper on which the toner image has been fixed is delivered to a paper refeed system 140. The paper refeeding system 140 guides the transfer paper to the paper discharge roller 14C by the action of the switching claw 141, except when copying the first side in the duplex mode. When copying the first side in duplex mode, the trailing edge of the transfer paper is guided to the reversing guide 143, and when the trailing edge of the transfer paper passes the switching pawl 141, the switching pawl 141 is switched, and the contact/separation roller 142 comes into contact to move the transfer paper to the reversing roller. 1
Send to 44. In addition, in the composition mode, the roller 14C is reversed at a predetermined timing before the rear end of the transfer paper guided by the discharge roller 14C passes through the discharge roller 14C, and the transfer paper is sent to the reversing roller 144.

The reversing roller 144 feeds the gate pawl 145 . There are four gate claws 145, and when the gate claws corresponding to the size of the transfer paper are opened, the transfer paper is discharged onto the intermediate tray 146. The transfer sheets that have fallen onto the intermediate tray 146 are brought together by a leading edge shifting roller 147 until they come into contact with a paper stopper 148, and their leading edges are aligned and stacked. At the second copy start of the second side of the duplex mode and the first side of the composite mode, the transfer sheets stacked on the intermediate tray 146 are transferred to the topmost sheet by the paper feed roller 14A and reverse roller 14B by the calling roller 149. is sent to the registration roller 135.

When detecting the toner concentration of the developing device 124, a standard pattern toner image is formed on the front side of the contact glass 111 prior to forming a toner image of the document, and its density is detected downstream of the developing device 124. P provided in
Read by sensor PSN. Further, 11 and 13 are sensors for detecting the width of the transfer paper, and 12 and 14 are sensors for detecting the length of the transfer paper. Details regarding this sensor will be described later. Next, referring to FIG.
H200 will be explained. The RDH 200 automatically feeds the original onto the contact glass 111 before starting optical scanning,
This is a type of automatic document feeder and ejector that ejects the ejected document after optical scanning is completed. By resetting the ejected document at the end (top in this example) and making it possible to repeatedly feed and eject the same document, it is possible to feed and eject double-sided documents. This is intended to facilitate re-copying in the event of copying or misfeeding. This device includes a document placing table 210, a document feeding system 220, a document resetting system 230, a reversing system 240, and the like. A recycle lever drive motor 211, a recycle lever 212 coupled to the shaft of the recycle lever drive motor 211, and a recycle lever 212 are mounted on the original table 210.
A sensor 213 is provided to detect the rotation of. When the original is set and copy start is instructed, the motor 21
1 rotates the recycle lever 212 and places it on the final document. After that, when the final original is fed and the lever 212 rotates due to its own weight, and the tip of the lever 212 falls from the notch formed in the original placing table 210, the sensor 212
detects the lever 212. In other words, the sensor 213 detects one cycle of the series of originals placed at the beginning. Further, when the number of document feed/discharge cycles is two or more, each cycle is detected by placing the lever 212 on the final document when it is reset at the end.

The feeding system 220 includes a half-moon roller 221, a feeding belt 222, a separating belt 223, a conveying roller 224,
It includes a conveyor belt 225, a presser roller 226, a document sensor 227, a paper feed sensor 228, a paper feed registration sensor 229, and the like. When the document sensor 227 detects a document, a feed-in signal is sent from the main body 100 at a predetermined timing. This starts the document feeding operation, and first, the half-moon roller 221 separates the document. Since a plurality of these documents may overlap, only the lowest document is sent to the conveyance roller 224 by the action of the feed belt 222 and separation belt 223. Conveyance roller 224 passes this document to conveyance belt 225, which further conveys it. At this time, when the registration sensor 229 detects the trailing edge of the document, a predetermined stop timing is set and the feeding of the document is stopped. This results in
A document is positioned on contact glass 111. Note that the paper feed sensor 228 detects misfeed.

The reset system 230 includes a deflection plate 231, discharge rollers 232, 233, and 234, and the like. Resetting is performed by completing the optical scan, and after selecting the ejection guide 235 by the direction change plate 231, the conveyor belt 225 is reversed. As a result, the last part of the document on the document tray (
is discharged to the top).

The reversing system 240 includes the switchback roller 2
41, a reversal sensor 242, a reversal registration sensor 243, and part of the original feeding system 220 and original resetting system 230 are used together. Here, the document resetting system 230
During ejection, the reversal sensor 242 detects the point at which the trailing edge of the document passes the ejection guide 235, and the document is guided to the switchback roller 241 by reversing the ejection rollers 232, 233, and 234. The switchback roller 241 first guides the document to a reversing guide 244 , then reverses it and guides it to a reversing paper feed guide 245 . At this time, the reversing paper feed guide 245 is selected by the direction change plate 231 and the document is sent to the conveyor belt 225. Note that the timing of stopping the document in this case is determined by detection by the reversal registration sensor 243.

The operations of the document feeding system 220, document resetting system 230, and reversing system 240 described above allow the document to be fed normally and ejected normally in the "normal feed and eject mode", and the document to be reversed and fed. "Reverse feed forward/discharge mode" that feeds and discharges as is.
"Normal feed/counter-discharge mode" in which the document is normally fed, reversed and ejected, "Reverse feed/counter-discharge mode" in which the document is reversed, fed, reversed and ejected, and "Reverse" is simply reversed. mode” becomes possible.

FIG. 3 shows a part of the external appearance of the operation board 150 provided in this copying apparatus. Each key and display will be explained. Reference numeral 1 is a print start key for inputting copy start instructions, number 2 is a mode clear key for clearing each mode, reference numeral 3 is a stop/clear key for inputting instructions such as clearing the number of copies in a copy set and interrupting copying.
Reference numeral 4 indicates a numeric keypad for inputting the number of copies to be set, etc., reference numeral 5 indicates a 7-segment display for the number of originals set, and reference numeral 6 indicates a 7-segment display for the number of copies to be processed. Further, reference numeral 7 is a double-sided copy mode key for copying from a double-sided original onto both sides of transfer paper, reference numeral 8 is a double-sided copy mode key for copying from a single-sided original to both sides of transfer paper, and reference numeral 9 is a double-sided copy mode key for copying from a single-sided original to both sides of transfer paper. A copy mode key 10 is used to make a copy on one side of transfer paper, and a composite copy mode key 10 is used to feed the copy paper once again and combine it with another original image to make a copy. Note that there are various other keys and indicators on the operation board 150, such as density adjustment and magnification keys, but they are omitted here.

FIG. 4 schematically shows the mechanical configuration of the transfer paper sensor. This mechanism is provided upstream of the fixing device 12C. The transfer paper sensor 11 is attached to a moving body 20 that is supported so as to be movable in a direction perpendicular to the traveling direction of the transfer paper. Further, the movable body 20 is moored to a drive wire 21 and is moved at a constant speed by a motor 24 via pulleys 22 and 23. In addition, the guide rod 25, pulleys 22, 23
and the motor 24 are all fixed to the main body of the copying machine. Note that the transfer paper sensor 13 provided on the downstream side of the fixing device 12C also has the same configuration as the transfer paper sensor 11 shown in FIG. 4.

Next, calculation of the width and length direction of the transfer paper will be explained. Transfer paper width sensor 1 is controlled by the mechanism shown in Fig. 4.
1 (13) and the transfer paper conveyance speed V4 are constant speeds, the width of the transfer paper can be derived from the time from the detection ON signal to the detection OFF signal of the width sensor 11 (13). Regarding the length, the transfer paper sensor 12 (installed on the upstream side of the fixing device 12C) fixed in the main body conveyance path, and the transfer paper sensor 14 (installed on the downstream side of the fixing device 12C)
The length can be derived directly from the sensor detection time.

FIG. 5 shows the sensor configuration, and FIG. 6 shows the sensor output. A reflective type sensor is used as the sensor, and as shown in FIG. 6, the sensor is turned on/off depending on the presence/absence of transfer paper. Therefore, move (transport)
It is possible to detect the time Δt when ON/OFF is switched at the end of the transfer paper and the presence of the transfer paper is detected.

The components described above are controlled by an electrical control system shown in FIG. This electrical control system includes a main control section 400, a storage section 410, an optical control section 420,
It consists of an AC control section 430, an operation control section 440, an RDH control section 450, and the like.

The main control unit 400 monitors various sensors 420 (including a transfer paper size sensor) provided in each part of the main body 100 and controls the loads of solenoids, motors, etc. of each part. The optical control unit 420 controls the lens motor that drives the lens 114 and the scanner motor that performs optical scanning, and the AC control unit 430 controls the exposure lamp 112, the heater of the fixing device 12C, the main motor, the developing motor, and the transport motor. and controls AC loads such as the paper feed motor. The operation control section 440 performs key operation reading and display control on the operation and display board 150. Further, the RDH control unit 450 controls the RDH 200.

FIGS. 8 and 9 outline the processing procedure of the main control unit 400 during double-sided copying. First, when duplex copying is instructed on the operation board (either key 7 or 8 is pressed) and a start instruction is given, the duplex counter is reset (Step a1: Hereinafter, the word step is omitted in parentheses. ), and the memory counter N=0 (a2). Next, front side copy mode processing (settings necessary for front side copying, etc.) is performed (a3). Thereafter, copy processing is performed (a4). This copy processing is an image forming process with reference to FIG. Width W of transfer paper detected by sensors 11 and 13 during copy processing
1 and W2, and also read the lengths L1 and L2 of the transfer paper detected by the sensors 12 and 14, calculate the correction amount, and store this in the memory (a5 to a8).

Now, to explain the calculation of the correction amount (a7), from the transfer paper width W1 detected by the pre-fixing transfer paper sensor 11 and the transfer paper width W2 detected by the post-fixing transfer paper sensor 13, the width correction amount= Calculate W2/W1. Also,
The length L1 of the transfer paper detected by the pre-fixing transfer paper sensor 12 and the length L2 of the transfer paper detected by the post-fixing transfer paper sensor 14
From this, length correction amount=L2/L1 is calculated. Note that when using only width sensors 11 and 13, width correction amount =
W2/W1, length correction amount = W2/W1. If only length sensors 12 and 14 are used, width correction amount = L2/L1, length correction amount = L2/L1. Bye. This is because it is known empirically that the same transfer paper has approximately the same shrinkage rate in the length direction and width direction.

Each time the copying process for one sheet is completed, the value of the duplex counter and the value of the memory counter N are incremented by 1 (a9, a10), and steps a4 to a10 are repeated until the value of the duplex counter becomes equal to the number of sheets set. The process is repeated (a11).

[0028] When the front side copy is completed, perform the back side copy processing (settings etc. required for performing the back side copy).
a12). Next, the correction data is called from the memory and the vertical magnification and the horizontal magnification are corrected (a13 to a15).

Here, vertical magnification and horizontal magnification correction (a14
, a15), the correction is performed as follows: vertical magnification after correction=setting magnification (mt)×(L2/L1) and horizontal magnification after correction=setting magnification (mr)×(W2/W1). For example, L1=100, W1=100, m
t=100%, L2=99, W2=99, mr=100
%, vertical magnification after correction = (mt) x (L2/L1) = 100 x 9
9/100 = 99%, that is, perform correction control to expose at the scanner speed when the magnification is 99%, and after correction lateral magnification = (mr) x (W2/W1) = 100 x 99/100 =
99%, that is, the movement correction is performed to the positions of the lenses and mirrors of the optical system when the magnification is 99%. After the correction, image formation is performed on the back side of the transfer paper under the corrected conditions (a16),
The values of the double-sided counter and memory counter N are decremented by 1 (a17, a18), and the processes of steps a13 to a18 are repeated until the value of the double-sided counter becomes 0 (a1
9).

After that, the vertical and horizontal magnification corrections are canceled, the correction data memory is cleared, the normal copying state is restored, and the double-sided copy mode is ended (a20 to a22).
). As described above, in this embodiment, in the double-sided copy mode, each time an image is formed on the front side of a series of transfer papers, the size of the transfer paper is detected before and after fixing, and the distortion caused by fixing is detected. Each time an image is formed on the back side of the transfer paper, the magnification of the image formation is corrected according to the distortion of the transfer paper due to fixing.

[0031]

[Embodiment 2] In the second embodiment, the hardware configuration is the same as in the first embodiment, but the control operation of the main control section 400 is different. This control operation is shown in FIG. First, when double-sided copying is instructed on the operation board and a start instruction is given, the same processing as shown in steps a1 to a11 (FIG. 8) of the first embodiment is performed on the front side of the transfer paper. When the front side copy is completed, the average value of the memory input data is calculated (b1), and the back side copy process (settings necessary for performing the back side copy, etc.) is performed (b2). Next, the correction data is called from the memory card, and the vertical magnification and the horizontal magnification are corrected (b3 to b5).

Here, vertical magnification and horizontal magnification correction (a14
, a15), correction is performed as follows: Vertical magnification after correction=setting magnification (mt)×(L2/L1) horizontal magnification after correction=setting magnification (mr)×(W2/W1). For example, L1=100, W1=100,
mt=100%, L2=99, W2=99, mr=10
If it is 0%, vertical magnification after correction = (mt) x (L2/L1) = 100 x 9
9/100 = 99%, that is, perform correction control to expose at the scanner speed when the magnification is 99%, and after correction lateral magnification = (mr) x (W2/W1) = 100 x 99/100 =
In other words, movement correction is performed on the lens and mirror positions of the optical system when the magnification is 99%.

After the correction, image formation is performed on the back side of the transfer paper under the corrected conditions (b6), the value of the double-sided counter is decremented by 1 (b7), and the process continues until the value of the double-sided counter reaches 0 (step b6). , b7 is repeated (b8). After that, cancel the vertical magnification and horizontal magnification correction, and use the correction data.
The data memory is cleared to return to the normal copying state, and the double-sided copy mode is ended (b9 to b11).

As described above, in this embodiment, in the double-sided copy mode, each time an image is formed on the front side of a series of transfer sheets, the size of the transfer sheet is detected before and after fixing, and distortion due to fixing is detected. However, before forming images on the back side of a series of transfer sheets, the magnification of image formation is corrected in accordance with the distortion of the transfer sheets due to fixing.

[0035]

[Third Embodiment] In this third embodiment, the hardware configuration is the same as that in the first embodiment, but the control operation of the main control section 400 is different. This control operation is shown in FIG. First, when double-sided copying is instructed on the operation board and a start instruction is given, the double-sided counter is reset (c1) and the memory counter N=0 (c2). Next, front side copy mode processing (settings necessary for front side copying, etc.) is performed (c3), and copy processing is performed (c4).

It is checked whether the number of originals placed is the first one, and if not, the process advances to step c9. When the number of originals placed is the first, the widths W1 and W2 of the transfer paper detected by sensors 11 and 13 are read, and the widths W1 and W2 of the transfer paper detected by sensors 11 and 13 are read.
The lengths L1 and L2 of the transfer paper detected in step 4 are read, the correction amount is calculated, and this is stored in the memory (c5 to c8). Here, to explain the calculation of this correction amount (c7), the transfer paper width W1 detected by the pre-fixing transfer paper sensor 11,
From the transfer paper width W2 detected by the post-fixing transfer paper sensor 13,
Calculate width correction amount = W2/W1. Further, a length correction amount=L2/L1 is calculated from the length L1 of the transfer paper detected by the pre-fixing transfer paper sensor 12 and the length L2 of the transfer paper detected by the post-fixing transfer paper sensor 14. Note that when using only width sensors 11 and 13, width correction amount = W2/W1,
It is sufficient to calculate the length correction amount = W2/W1, and when using only the length sensors 12 and 14, the width correction amount =
It may be calculated as L2/L1, length correction amount=L2/L1.

Each time the copying process for one sheet is completed, the value of the duplex counter and the value of the memory counter N are incremented by 1 (c8, c9), and steps c3 to c9 are repeated until the value of the duplex counter becomes equal to the number of sheets set. The process is repeated (c10).

When the front side copy is completed, back side copy mode processing (S1) is performed. This processing is the same as the processing shown in steps a12 to a22 (FIG. 9) shown in the first embodiment.

As described above, in this embodiment, when forming an image on the front side of a series of transfer papers in the double-sided copy mode, the size of the transfer paper is detected before and after fixing the first transfer paper. Distortion due to fixing is detected, and before images are formed on the back side of a series of transfer sheets, the magnification of image formation is corrected in accordance with the distortion of the transfer sheets due to fixing.

[0040]

[Fourth Embodiment] In this fourth embodiment, the hardware configuration is the same as in the first embodiment, but the control operation of the main control section 400 is different. FIGS. 12 and 13 outline the processing procedure of the main control unit 400 during composite copying. First, when a composite copy is instructed on the operation board (key 10 is pressed) and a start instruction is given, the composite counter is reset (d1) and the memory counter is set to 0 (d2).
). Next, initial copy mode processing (settings necessary for performing the first copy, etc.) is performed (d3). Thereafter, copy processing is performed (d4). This copy processing is an image forming process with reference to FIG. Transfer paper width W1, W detected by sensors 11 and 13 during copy processing
2, and also read the lengths L1 and L2 of the transfer paper detected by the sensors 12 and 14, calculate the correction amount, and store this in the memory (d5 to d8). Here, to explain the calculation of this correction amount (d7), from the transfer paper width W1 detected by the pre-fixing transfer paper sensor 11 and the transfer paper width W2 detected by the post-fixing transfer paper sensor 13, the width correction amount = W2/
Calculate W1. Further, from the length L1 of the transfer paper detected by the pre-fixing transfer paper sensor 12 and the length L2 of the transfer paper detected by the post-fixing transfer paper sensor 14, the length correction amount = L2/L1
Calculate. Note that when using only width sensors 11 and 13, width correction amount = W2/W1, length correction amount = W2
/W1, and the length sensors 12 and 1
If only 4 is used, the width correction amount may be calculated as L2/L1, and the length correction amount may be calculated as L2/L1.

Each time the copying process for one sheet is completed, the value of the composition counter and the value of the memory counter N are incremented by 1 (d9, d10), and steps d4 to d10 are repeated until the value of the composition counter becomes equal to the set number of copies. The process is repeated (d11).

[0042] When the first copy is completed, composite copy processing (settings necessary for performing the second copy, etc.) is performed (d12). Next, recall the correction data from memory and
Correct the vertical magnification and horizontal magnification (d13 to d15)
.

Here, vertical magnification and horizontal magnification correction (d14
, d15), the correction is performed as follows: vertical magnification after correction=setting magnification (mt)×(L2/L1) and horizontal magnification after correction=setting magnification (mr)×(W2/W1). For example, L1=100, W1=100, m
t=100%, L2=99, W2=99, mr=100
%, vertical magnification after correction = (mt) x (L2/L1) = 100 x 9
9/100 = 99%, that is, perform correction control to expose at the scanner speed when the magnification is 99%, and after correction lateral magnification = (mr) x (W2/W1) = 100 x 99/100 =
In other words, movement correction is performed on the lens and mirror positions of the optical system when the magnification is 99%.

After the correction, image formation is performed on the surface of the transfer paper under the corrected conditions (d16), and the values of the composition counter and memory counter N are decremented by 1 (d17, d16).
18) Then, the processes of steps d13 to d18 are repeated until the value of the synthesis counter becomes 0 (d19).

After that, the correction of the vertical magnification and the horizontal magnification is canceled, the correction data memory is cleared, the normal copying state is restored, and the composite copy mode is ended (d20 to d22).
). As described above, in this embodiment, in the composite copy mode, each time an image is formed on the front side of a series of transfer papers, the size of the transfer paper is detected before and after fixing, and the distortion caused by fixing is detected. Each time a composite image is formed on the front side of the transfer paper, the magnification of the image formation is corrected in accordance with the distortion of the transfer paper due to fixing.

[0046]

[Embodiment 5] In this embodiment 5, the hardware configuration is the same as in the embodiment 1, but the control operation of the main control section 400 is different. FIG. 14 shows this control operation. First, when composite copying is instructed on the operation board and a start instruction is given, the same processing as shown in steps d1 to d11 (FIG. 12) of the fourth embodiment is performed on the front surface of the transfer paper. When the front side (first time) copying is completed, the average value of the memory input data is calculated (e1), and the second (composite) copying process (settings necessary for performing composite copying, etc.) is performed (e2). Next, the correction data is called from the memory and the vertical magnification and the horizontal magnification are corrected (e3 to e5).

Here, vertical magnification and horizontal magnification correction (d14
, d15), the correction is performed as follows: vertical magnification after correction=setting magnification (mt)×(L2/L1) and horizontal magnification after correction=setting magnification (mr)×(W2/W1). For example, L1=100, W1=100, m
t=100%, L2=99, W2=99, mr=100
%, vertical magnification after correction = (mt) x (L2/L1) = 100 x 9
9/100 = 99%, that is, perform correction control to expose at the scanner speed when the magnification is 99%, and after correction lateral magnification = (mr) x (W2/W1) = 100 x 99/100 =
In other words, movement correction is performed on the lens and mirror positions of the optical system when the magnification is 99%.

After the correction, a composite image is formed on the surface of the transfer paper under the corrected conditions (e6), and the value of the composite counter is decremented by 1 (e7), until the value of the composite counter becomes 0.
Repeat steps e6 and e7 until e8
). After that, cancel the vertical and horizontal magnification corrections, clear the correction data memory, and return to the normal copying state.
The composite copy mode is ended (e9 to e11).

As described above, in this embodiment, in the composite copy mode, each time an image is formed on the front side of a series of transfer sheets, the size of the transfer sheet is detected before and after fixing, and the distortion caused by fixing is detected. However, before forming a composite image on the front side of a series of transfer sheets, the magnification of image formation is corrected according to the distortion of the transfer sheet due to fixing.

[0050]

[Embodiment 6] In this Embodiment 6, the hardware configuration is the same as in Embodiment 1, but the control operation of the main control section 400 is different. FIG. 15 shows this control operation. First, when a composite copy is instructed on the operation board and a start instruction is given, the composite counter is reset (f1) and the memory counter N is set to 0 (f2). Next, the surface (first time)
Copy mode processing (settings necessary for front side copying, etc.) is performed (f3), and copy processing is performed (f4).

It is checked whether the number of originals placed is the first one, and if not, the process advances to step f9. When the number of originals placed is the first, the widths W1 and W2 of the transfer paper detected by sensors 11 and 13 are read, and the widths W1 and W2 of the transfer paper detected by sensors 11 and 13 are read.
The lengths L1 and L2 of the transfer paper detected in step 4 are read, the correction amount is calculated, and this is stored in the memory (f5 to f8). Here, to explain the calculation of this correction amount (f7), the transfer paper width W1 detected by the pre-fixing transfer paper sensor 11,
From the transfer paper width W2 detected by the post-fixing transfer paper sensor 13,
Calculate width correction amount = W2/W1. Further, a length correction amount=L2/L1 is calculated from the length L1 of the transfer paper detected by the pre-fixing transfer paper sensor 12 and the length L2 of the transfer paper detected by the post-fixing transfer paper sensor 14. Note that when using only width sensors 11 and 13, width correction amount = W2/W1,
It is sufficient to calculate the length correction amount = W2/W1, and when using only the length sensors 12 and 14, the width correction amount =
It may be calculated as L2/L1, length correction amount=L2/L1.

Each time the copying process for one sheet is completed, the value of the composition counter and the value of the memory counter N are incremented by 1 (f8, f9), and steps f3 to f9 are repeated until the value of the composition counter becomes equal to the set number of copies. The process is repeated (f10).

When the front side (first time) copying is completed, second (composite) copy mode processing (S2) is performed. This process is performed in steps d12 to d22 (FIG. 13) shown in Example 4.
This is the same process as shown in .

As described above, in the sixth embodiment, when forming an image on the front side of a series of transfer papers in the composite copy mode, the size of the transfer paper is changed before and after fixing the first transfer paper. The distortion caused by fixing is detected, and the magnification of image formation is corrected in accordance with the distortion of the transfer paper caused by fixing before forming a composite image on the front side of a series of transfer papers.

In Examples 1 to 6 described above, when the magnification is corrected according to the distortion of the transfer paper due to fixing, the magnification (vertical magnification and However, in each embodiment, the vertical magnification can be corrected by changing the rotational speed of the photoreceptor and the conveyance speed of the transfer paper. This correction will be explained below.

First, the calculation of the correction amount will be explained.
A width correction amount = W2/W1 is calculated from the transfer paper width W1 detected by the pre-fixing transfer paper sensor 11 and the transfer paper width W2 detected by the post-fixing transfer paper sensor 13. Further, a length correction amount=L2/L1 is calculated from the length L1 of the transfer paper detected by the pre-fixing transfer paper sensor 12 and the length L2 of the transfer paper detected by the post-fixing transfer paper sensor 14. Note that when using only the width sensors 11 and 13, the width correction amount = W2/W1 and the length correction amount = W2/W1 may be used. When using only the length sensors 12 and 14, the width Correction amount = L
2/L1, length correction amount=L2/L1.

Next, when performing correction using this correction amount, correction speed = set speed (Vo) x reciprocal of length correction amount (L1
/L2) Lateral magnification after correction = Setting magnification (mr) x Width correction amount (W2/W
1) Correct as follows. For example, L1=100, W1=1
00, Vo=100 (mm/s), L2=99, W2=
99, mr = 100%, correction speed = (Vo) x (L1/L2) = 100 x 100
/99=101 (mm/s) That is, correction control is performed to change the rotational speed of the photoreceptor and the transport speed of the transfer paper to 101 (mm/s) for exposure, and the horizontal magnification after correction = (mr) ×(W2/W1)=100×9
9/100=99%, that is, movement correction is performed on the lens and mirror positions of the optical system when the magnification is 99%.

Note that when changing the rotational speed of the photoreceptor and the conveyance speed of the transfer paper, this is done by controlling the rotational speeds of the main motor and the conveyance motor to adjust them to predetermined rotational speeds. Since this is already known, the description thereof will be omitted.

[0059]

As described above, according to the present invention, the detection means (11, 12, 13, 14) detects the image forming means (11, 14).
The distortion of the transfer paper caused by the fixing device (12C) of 0.0, 120) is detected, and the correction control means (400) changes the image forming magnification of the image forming means (110, 120) at a predetermined timing according to this distortion. do. Therefore, when forming an image twice on one sheet of transfer paper for double-sided copying or composite copying, the distortion of the transfer paper during the first image formation is detected, and the image formed during the second image formation is adjusted according to the distortion. By setting the correction timing to change the formation magnification, it is possible to absorb distortion in image formation caused by distortion of the transfer paper in the second time.
Stable image formation can be performed.

[Brief explanation of drawings]

FIG. 1 is a side view showing a schematic configuration of an image forming section of a copying apparatus 100 of the present invention.

FIG. 2 is a side view showing a schematic configuration of an RDH 200 provided in the copying apparatus 100.

[Fig. 3] Operation board 150 provided in the copying apparatus 100
2 is a plan view schematically showing a part of the FIG.

FIG. 4 is a perspective view showing an outline of the mechanism of the transfer paper size sensor 11 (13).

[Figure 5] Transfer paper size sensor 11 (12, 13, 1
4) is a plan view schematically showing the sensor section of FIG.

FIG. 6 is a time chart showing an example of ON/OFF timing of the sensor 11.

FIG. 7 is a block diagram schematically showing a control system of the present invention.

FIG. 8 is a flowchart showing the control operation of the main control unit 400 during double-sided copying (Embodiment 1).

FIG. 9 is a flowchart showing the control operation of the main control unit 400 during double-sided copying (Embodiment 1).

FIG. 10 is a flowchart showing the control operation of the main control unit 400 during double-sided copying (Embodiment 2).

FIG. 11 is a flowchart showing the control operation of the main control unit 400 during double-sided copying (Embodiment 3).

FIG. 12 is a flowchart showing the control operation of the main control unit 400 during composite copying (Embodiment 4).

FIG. 13 is a flowchart showing the control operation of the main control unit 400 during composite copying (Embodiment 4).

FIG. 14 is a flowchart showing the control operation of the main control unit 400 during composite copying (Embodiment 5).

FIG. 15 is a flowchart showing the control operation of the main control unit 400 during composite copying (Embodiment 6).

[Explanation of symbols]

100: Copying machine main body 110: Optical system
120: Image forming system (110, 120: Image forming means) 130: Paper feeding system
140: Paper refeed system 150: Operation board 7, 8: Double-sided copy mode key (instruction means) 10: Composite copy mode key (instruction means) 11, 12, 13, 14
: Transfer paper sensor (detection means) 200: Automatic document feeder 210: Document placement table
220: Original feeding system 230: Original resetting system 400: Main control section (correction control means) 410: Storage section 420
:Optical control section 430:AC control section
440: Operation control unit 450: RDH control unit (200, 450: Original supply/discharge control means)

Claims (27)

[Claims] Claims: 1. Original supply/discharge control means for sequentially supplying originals one by one from a series of original sets to an exposure position and ejecting them to a predetermined position after exposure; An electrostatic latent image is formed on a uniformly charged charge carrier, the latent image is developed with a developing device, and the developed image is transferred to transfer paper, and then fixed with a fixing device. an image forming means for forming an image on a transfer paper; a detection means for detecting distortion of the transfer paper caused by the fixing device of the image forming means; an instruction means; a transfer paper refeeding unit for stacking transfer papers and sequentially feeding the transfer papers to the image forming means so as to form an image again on the image forming surface or the back side of the image forming surface; An image forming apparatus comprising: a correction control means for changing an image forming magnification of an image forming means at a predetermined timing according to distortion; 2. The detecting means is a detecting means for detecting the width of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means detects the width of the transfer paper before and after the fixing of the fixing device. 2. The image forming apparatus according to claim 1, wherein the correction control means performs the correction every time a series of transfer sheets are fed by the transfer sheet refeeding means.
The image forming apparatus described above. 3. The detecting means is a detecting means for detecting the length of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means detects the length of the transfer paper before and after the fixing of the fixing device. The method according to claim 1, further comprising instructing image formation on the reverse side of the image forming surface of the subsequent transfer paper, and further comprising: the correction control means performing the correction every time a series of transfer paper is fed by the transfer paper refeeding means. 1. The image forming apparatus according to 1. 4. The detecting means is a detecting means for detecting the width and length of the transfer paper before and after fixing by the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means includes: The above method is characterized in that it instructs to form an image on the reverse side of the image forming surface of the transfer paper after the image formation, and further, the correction control means performs the correction every time a series of transfer paper is fed by the transfer paper refeeding means. The image forming apparatus according to claim 1. 5. The detecting means is a detecting means for detecting the width of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means detects the width of the transfer paper before and after the fixing of the fixing device, and the indicating means detects the width of the transfer paper after the image is formed. 2. The image forming apparatus according to claim 1, wherein the correction control means performs correction before feeding a series of transfer sheets to the transfer sheet refeeding means.
The image forming apparatus described above. 6. The detecting means is a detecting means for detecting the length of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means detects the length of the transfer paper before and after the fixing of the fixing device. The method according to claim 1, wherein image formation is instructed on the reverse side of the image forming surface of the subsequent transfer sheet, and further, the correction control means performs correction before feeding a series of transfer sheets to the transfer sheet refeeding means. 1. The image forming apparatus according to 1. 7. The detecting means is a detecting means for detecting the width and length of the transfer paper before and after fixing by the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means includes: The above method is characterized in that it instructs to form an image on the reverse side of the image forming surface of the transfer paper after the image formation, and further, the correction control means performs the correction before feeding a series of transfer papers to the transfer paper refeeding means. The image forming apparatus according to claim 1. 8. The detecting means is a detecting means for detecting the width of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the indicating means detects the width of the transfer paper before and after the fixing of the fixing device. 2. The method of claim 1, wherein image formation is instructed on the image forming surface of a subsequent transfer sheet, and the correction control means performs correction before feeding a series of transfer sheets to the transfer sheet refeeding means.
The image forming apparatus described above. 9. The detecting means is a detecting means for detecting the length of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the indicating means detects the length of the transfer paper before and after the fixing of the fixing device. Claim 1, further comprising: instructing image formation on the image forming surface of the transfer paper after formation, and further comprising: the correction control means performing correction before feeding a series of transfer papers to the transfer paper refeeding means. The image forming apparatus described above. 10. The detecting means is a detecting means for detecting the width and length of the transfer paper before and after fixing by the fixing device at the time of forming a series of initial images before refeeding the transfer paper, and the indicating means The above claim instructs to form an image on the image forming surface of the transfer paper after the image has been formed, and further, the correction control means performs the correction before feeding a series of transfer sheets to the transfer paper refeeding means. Item 1. Image forming apparatus according to item 1. 11. The detecting means is a detecting means for detecting the width of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means detects the width of the transfer paper before and after the fixing of the fixing device. 2. The image forming apparatus according to claim 1, wherein the correction control means performs the correction every time a series of transfer sheets are fed by the transfer sheet refeeding means. The image forming apparatus described above. 12. The detecting means is a detecting means for detecting the length of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the instruction means detects the length of the transfer paper before and after the fixing of the fixing device. Instruct image formation on the image forming surface of the subsequent transfer paper,
2. The image forming apparatus according to claim 1, further characterized in that said correction control means performs correction each time a series of transfer sheets are fed by a transfer sheet refeeding means. 13. The detecting means is a detecting means for detecting the width and length of the transfer paper before and after fixing by the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means includes: The above method is characterized in that it instructs to form an image on the surface of the image forming surface of the transfer paper after the image formation, and further, the correction control means performs the correction every time a series of transfer paper is fed by the transfer paper refeeding means. The image forming apparatus according to claim 1. 14. The detecting means is a detecting means for detecting the width of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means detects the width of the transfer paper before and after the fixing of the fixing device, and the indicating means 2. The apparatus according to claim 1, wherein the correction control means performs the correction before feeding a series of transfer sheets to the transfer sheet refeeding means. Image forming device. 15. The detecting means is a detecting means for detecting the length of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the instruction means detects the length of the transfer paper before and after the fixing of the fixing device, and the instruction means 2. The method according to claim 1, wherein the image formation surface of the subsequent transfer sheet is instructed to form an image, and the correction control means performs the correction before the transfer sheet refeeding section feeds the series of transfer sheets. image forming device. 16. The detecting means is a detecting means for detecting the width and length of the transfer paper before and after fixing by the fixing device for each series of image formation before refeeding the transfer paper, and the indicating means includes: The method according to claim 1, wherein image formation is instructed on the image forming surface of the transfer paper after the image has been formed, and further, the correction control means performs correction before feeding a series of transfer paper to the transfer paper refeeding means. 1. The image forming apparatus according to 1. 17. The detecting means is a detecting means for detecting the width of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the indicating means detects the width of the transfer paper before and after the fixing of the fixing device. 2. The method according to claim 1, wherein the image formation surface of the subsequent transfer sheet is instructed to form an image, and the correction control means performs the correction before the transfer sheet refeeding section feeds the series of transfer sheets. image forming device. 18. The detecting means is a detecting means for detecting the width of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the instruction means detects the width of the transfer paper before and after the fixing of the fixing device. 2. The method according to claim 1, wherein the image formation surface of the subsequent transfer sheet is instructed to form an image, and the correction control means performs the correction before the transfer sheet refeeding section feeds the series of transfer sheets. image forming device. 19. The detecting means is a detecting means for detecting the width of the transfer paper before and after fixing by the fixing device during the first series of image formation before refeeding the transfer paper, and the indicating means detects the width of the transfer paper before and after the fixing of the fixing device. 2. The method according to claim 1, wherein the image formation surface of the subsequent transfer sheet is instructed to form an image, and the correction control means performs the correction before the transfer sheet refeeding section feeds the series of transfer sheets. image forming device. 20. The detecting means is a detecting means for detecting the length of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the indicating means detects the length of the transfer paper before and after the fixing of the fixing device. Instruct image formation on the image formation surface of the transfer paper after formation,
Furthermore, the correction control means adjusts the focal length of the document exposure light, the transport speed of the transfer paper, and the rotational speed of the charge carrier of the image forming means before feeding a series of transfer papers to the transfer paper refeeding means. 2. The image forming apparatus according to claim 1, wherein the image forming magnification is changed by changing the image forming magnification. 21. The detecting means is a detecting means for detecting the length of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the instruction means detects the length of the transfer paper before and after the fixing of the fixing device. The correction control means instructs image formation on the image forming surface of the subsequent transfer paper, and furthermore, the correction control means adjusts the focal length of the original exposure light of the image forming means, the transfer Claim 1 characterized in that the image forming magnification is changed by adjusting the conveyance speed of the paper and the rotation speed of the charge carrier.
The image forming apparatus described above. 22. The detection means is a detection means for detecting the length of the transfer paper before and after fixing of the fixing device for each series of image formation before refeeding the transfer paper, and the instruction means detects the length of the transfer paper before and after the fixing of the fixing device, and the instruction means The correction control means instructs image formation on the image forming surface of the subsequent transfer paper, and furthermore, the correction control means adjusts the focal length of the document exposure light of the image forming means and the transfer value for each series of transfer paper fed by the transfer paper refeeding means. Claim 1 characterized in that the image forming magnification is changed by adjusting the conveyance speed of the paper and the rotation speed of the charge carrier.
The image forming apparatus described above. 23. The detecting means is a detecting means for detecting the width of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the indicating means detects the width of the transfer paper before and after the fixing of the fixing device. The correction control means instructs image formation on the image forming surface of the subsequent transfer sheet, and furthermore, the correction control means adjusts the focal length of the original exposure light of the image forming means before the transfer sheet refeeding means feeds the series of transfer sheets.
2. The image forming apparatus according to claim 1, wherein the image forming magnification is changed by adjusting the transfer speed of the transfer paper and the rotation speed of the charge carrier. 24. The detecting means is a detecting means for detecting the length and width of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the indicating means instructs to form an image on the image forming surface of the transfer paper after the image is formed, and furthermore, the correction control means controls the focus of the document exposure light of the image forming means before feeding a series of transfer sheets of the transfer paper refeeding means. 2. The image forming apparatus according to claim 1, wherein the image forming magnification is changed by adjusting the distance, the transfer speed of the transfer paper, and the rotation speed of the charge carrier. 25. The detecting means is a detecting means for detecting the length of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the indicating means detects the length of the transfer paper before and after the fixing of the fixing device. The correction control means instructs image formation on the back side of the transfer paper after the formation, and furthermore, the correction control means adjusts the focal length of the document exposure light of the image forming means before the transfer paper refeeding means feeds the series of transfer paper. 2. The image forming apparatus according to claim 1, wherein the image forming magnification is changed by adjusting the transfer speed of the transfer paper and the rotation speed of the charge carrier. 26. The detection means is a detection means for detecting the width of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the instruction means detects the width of the transfer paper before and after the fixing of the fixing device. Instruct image formation on the back side of the subsequent transfer paper,
Furthermore, the correction control means adjusts the focal length of the document exposure light, the transport speed of the transfer paper, and the rotational speed of the charge carrier of the image forming means before feeding a series of transfer papers to the transfer paper refeeding means. 2. The image forming apparatus according to claim 1, wherein the image forming magnification is changed by changing the image forming magnification. 27. The detecting means is a detecting means for detecting the length and width of the transfer paper before and after fixing by the fixing device during the first image formation in a series before refeeding the transfer paper, and the indicating means Instructs to form an image on the back side of the transfer paper after the image formation, and furthermore, the correction control means adjusts the focus of the document exposure light of the image forming means before feeding a series of transfer papers of the transfer paper refeeding means. 2. The image forming apparatus according to claim 1, wherein the image forming magnification is changed by adjusting the distance, the transfer speed of the transfer paper, and the rotation speed of the charge carrier.