JP2621177B2 - Image forming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus that transfers a toner image while shifting the toner image in the direction of travel of a transfer sheet, and more particularly to timing control of a developing bias.

2. Description of the Related Art Conventionally, in a copying machine, for example, an image shift mode is provided in order to provide a binding port on paper, and by specifying a shift amount, an image is moved rightward or leftward with respect to the paper. I have. That is, when the original is placed on the contact glass, the original is scanned from the right side, and the transfer paper is ejected in the opposite direction, so that when moving rightward, it is necessary to delay the traveling timing of the paper from the registration rollers, Conversely, when moving left, it is necessary to delay the lamp ON timing.

The present inventor has previously proposed a copier control system capable of efficiently moving an image even when the image exceeds the structural limit of the exposure and register rollers (Japanese Patent Application No. 61-167355).
No. and drawings).

However, in the conventional method, when controlling the bias of the copying machine, the bias is turned on when the leading end of the virtual image reaches the developing bias section by synchronizing with the image forming timing on another drum such as charging and exposure. ing. That is, background contamination within the image range on the drum is prevented. Therefore, in the method described in the specification of the above-mentioned prior application, that is, the method of intentionally shifting the transfer timing to move the image, the toner adheres to the outside of the image area on the drum. Outside soiling may be transferred. In this case, power consumption increases if a bias is continuously applied during copying. Also, the amount of toner attached to the bias portion outside the image range increases, and the toner is consumed quickly,
The deterioration of the photoreceptor due to the recovery of the residual toner causes a reduction in the developing ability.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional problem, and when a toner image is transferred while being shifted in the traveling direction of a transfer body, a transfer sheet due to transfer of a soiled portion outside an image range on a drum is transferred. The purpose of the present invention is to prevent the ground from becoming dirty.

To achieve the above object, the image forming apparatus of the present invention forms a toner image on a latent image carrier by a developing unit,
When an image is formed by transferring the toner image on the latent image carrier to a transfer member, the image forming apparatus transfers the toner image by shifting the toner image in a traveling direction of the transfer member. Characterized in that control means is provided at a timing synchronized with the progress of the process.

Hereinafter, the configuration of the present invention will be described in detail with reference to examples.

FIG. 2 is a sectional structural view of a monocolor copying machine to which the present invention is applied.

An automatic document feeder (hereinafter ADF)
2), a sorter 3 is provided on the side of the paper ejection side, and a paper feed tray is selectively provided on the paper supply side from either a two-stage paper supply cassette or a paper supply tray for large-volume paper supply. A paper feed unit 4 for feeding paper is attached.

The ADF 2 includes a document setting unit 7, an ADF paper feed roller 8, an ADF transport belt 9, a document discharge tray 10, and the like.
The sheet is fed and conveyed to the conveying belt 9, set on the contact glass 11 on the upper part of the copying machine main body 1, and discharged onto the document discharge tray 10 after the copying operation is completed. The ADF 2 is provided so that the whole can be opened and closed on the contact glass 11 with one side as an axis. Therefore, the ADF 2 serves as a document holding plate when a document is manually set on the contact glass 11.

The original set on the contact glass 11
Irradiated at 12. The reflected light from the original is reflected by the first mirror 13,
An image is formed on the surface of the photosensitive drum 20 via the second mirror 14, the third mirror 15, the lens unit 16 and the fourth mirror 17. The photoconductor drum 20 is driven to rotate clockwise by a main motor 21 via a power transmission mechanism (not shown). The lamp 12 and the first mirror 13 are mounted on a first carriage (not shown), and are driven at a constant speed in a direction A of an arrow. The second mirror 14 and the third mirror 15 are
It is mounted on a carriage (not shown) and is driven in the direction of arrow A at half the speed of the first carriage.

The surface of the photosensitive drum 20 is uniformly charged by the main charger 22. The charged surface is transmitted through the sub-divided erase unit 23 and is exposed by the above-mentioned image formation, thereby generating an electrostatic latent image on the surface of the photosensitive drum 20. This electrostatic latent image is
The toner image is developed with a developing solution of the developing device 24 to become a visible image, and is sent to the transfer charger unit 25.

The transfer paper is fed out from the paper feed unit 4 by the paper feed roller 26,
The transport rollers 27 and 28 reach the registration rollers 29.
Here, the visible image is transferred again to the transfer paper charger 25 along the paper guide at an appropriate timing. The recorded transfer paper is separated from the photosensitive drum 20 by the separation unit 30, guided by a paper guide 33, and sent out of the copying machine main body 1 from a paper discharge roller 34. In the sorter 3, the sheets are sorted and discharged according to a predetermined type.
Further, in the combination mode and double-sided copying, since printing is performed twice on one sheet of transfer paper, the sheet is conveyed downward by the switch 70 and is temporarily retracted at the retreat position 74 for recopying. Thereafter, the sheet is conveyed along the second conveying path by the rollers 79 and 80 and is conveyed again to the transfer charge 25 position. In the case of double-sided copying, when the transfer paper is directly conveyed from the retreat position 74 to the transfer charger 25, the back side is turned upside down.
The next transfer can be performed as it is. On the contrary,
In undercolor or other composite modes for printing on a single color, the next printing must be performed on the same side. Therefore, transfer the transfer paper at the second retreat position on the way, and then transport it to the transfer charger 25. Thus, printing can be performed on the same surface.

On the other hand, the surface of the photosensitive drum 20 is cleaned by the cleaning unit 35, and the main charger 22 is started again.

Red, green, and blue print liquids 6 are provided below the copying machine body 1.
2, 63 and 64 are separately arranged, each of which is independently piped to the photosensitive drum 20, and a copy liquid circulates between them.

FIG. 3 is a layout view of an operation panel showing one embodiment of the present invention.

When the color button is pressed from the left side, transition is made in the order of green, blue, red, and black. When the synthesizing button is pressed, one of the lamps of the under color and the synthesizing is turned on, and the mode is set. Pressing the shift button alternately turns on centering and image shift. Pressing the trim button alternately turns on delete and save. In the save mode, a part of the image area is designated and the other part is deleted while leaving the area part, and the delete mode is used to delete the area part. When you press the continuous shooting button,
One of the third and third divided copies is selected. When the exposure button is pressed, the density increases in order from right to left. When the cassette button is pressed, the cassettes set in the upper, middle and lower positions are sequentially selected. By pressing the corresponding one of the number buttons, the corresponding number is copied. When the print button is pressed, copying is actually executed. The number display on the upper right side is the total number of copies, and the symbols on the left side are U (upper), D (lower), L (left), R
(Right), X1, X2, Y1, and Y2 mean the distances displayed at the center. That is, when setting data for trimming or image shift, set the movement direction with the arrow above the button, and then set the symbol and the 210 mm below it.
The distance from the base point is set by setting data such as.

FIG. 4 is a configuration diagram of an LED array control circuit for partially erasing the charged surface on the drum in the copying machine of the present invention by the subdivision erase unit 23.

An array signal, which is data for turning on the LED array behind the LED to be turned on from the CPU, is sent by a clock signal to create a bit array corresponding to turning on and off the LED. Thereafter, by inputting a trigger in accordance with the lighting timing, the LED element group is selectively controlled. Note that one shift register and one driver are connected for every four LEDs, but this is only a shift register having four pin terminals. If a shift register with a large number of pins is used, one shift register and one driver are used. Only one LED can drive all LEDs.

 FIG. 5 is a configuration diagram of a control unit of the copying machine of the present invention.

An operation key switch group 8 of the copier, a machine state detection sensor 9, a pulse generator 10 for generating a pulse synchronized with the photosensitive drum 20, and the like are input to the CPU 1 via a buffer 11. The CPU 1 is connected to the ROM 3, the RAM 2, and the input / output port buffers 4, 5 via an address bus, a controller bus, a data bus, and the like. I / O port buffers 4, 5
Are connected via a driver 6 to loads such as driving and display.

FIG. 6A is a flowchart of the basic operation of the copying machine to which the present invention is applied.

When the power of the copying machine is turned on, a power-on initialization process is performed, a pre-print process A and a copy pre-process B are performed, and then a copy process C is started. When the copy process C is completed, a copy end process D is performed, and a pre-process for the next copy is performed.
Alternatively, the end processing is repeated to wait.

FIG. 6B is a detailed flowchart of the print preprocessing A in FIG. 6A.

In the print preprocessing A, first, the input / output processing is performed, the mode setting processing A-1 is performed, and then the abnormality check is performed. If there is an abnormality, an abnormal process is performed. If there is no abnormality, a print preparation process A-2 is performed, a print condition check A-3 is performed, and if print is possible, a print start check is performed. It is determined whether or not the print start has been turned ON. If printing is not possible or print start is not ON, the process returns to the beginning and performs input / output processing.

FIGS. 7A and 7B are flowcharts of the copy pre-processing and the copy processing.

In the copy pre-processing (B) of FIG.
After the initialization, the input / output processing and the abnormality check are performed, and if there is no abnormality, the pre-copy operation processing is performed. If there is an abnormality, the flow branches to an abnormality processing routine.

In the copy process (C) of FIG. 7B, after initial setting, input / output processing and abnormality check are performed. If there is no abnormality, repeat processing and repeat timing check are performed. When the repeat end check is performed to confirm that the repeat is completed, the flow branches to a copy end processing routine.

Trimming Mode As described above, the trimming mode includes a save mode in which a part of an image area is designated and the other area is erased while leaving the area, and a delete mode in which the area is erased. The program mode is set by combining the trimming mode and the combining mode.

Next, a data input operation in the trimming mode will be described.

(Data input) (a) Enter the size of the document to be trimmed.

(B) To specify the trimming area, input the distance from the reference point to the four corners of the trimming area using the direction keys.

(C) First, input the X1 data using the right key.

(D) After inputting the X1 data, use the Enter key to save the data to X1.
Store it in the data memory and turn on the X2 data input flag for X2 data input.

(E) Input the X2 data and store it in the X2 data memory with the enter key.

(F) Input the Y1 and Y2 data in the same way.

(G) If all input of trimming data is completed and shift mode, program mode, etc. are not set,
Pressing the enter key sets a data set end flag and ends data input.

Next, the data conversion process is a process of creating control data of the LED array from the input data.

(Data conversion) (a) The center coordinates of the original paper trimming area are obtained from the original size, paper size, and trimming area data.

(B) If there is movement, increase or decrease the movement amount in the trimming area data.

(C) In the case of magnification and combination, the data converted by the movement amount is converted to a value obtained by multiplying by a magnification.

(D) Using the data converted in each of the above modes, LE
Convert to D array lighting data.

 Next, the copy operation will be described in detail.

(Copy operation) (A) Among the trimming area data, the Y direction data is
The LED array lighting number and X direction data are data for determining the LED array lighting timing, and are transmitted to the optical system (sent together with data such as an optical system start signal and size data).

(B) The optical system converts the X-direction data into position data from the start of the scanner, and transmits the data as a trimming signal to the main body when the scanner reaches the corresponding position.

(C) Receiving the trimming signal from the optical system, controlling the lighting of the LED corresponding to _Xn , and deleting or saving the image area on the drum.

Next, a shift mode for moving or centering a trimmed image will be described.

Shift mode (mode setting) (a) Pressing the shift key on the operation board sets the image shift, centering or OFF mode in the image shift setting routine.

(B) The corresponding mode display on the operation board lights.

(C) If the shift mode is set after setting the magnification mode, the mode changes to the partial magnification mode.

(D) If the shift mode is set after the combination mode or the under color mode is set, the program mode is set.

(Data Input) (a) Image shift data input is performed by pressing a key in the direction in which the user wants to move.

(B) When the left / right and up / down keys are pressed, data is input to X or Y, and the direction flag is set.

(C) The direction indication on the board is turned on by the data and the direction flag, and the movement data is displayed.

(D) When the enter key is pressed for each input, the data is stored in the memory.

(E) If the enter key is pressed without inputting the data key, the previous data is maintained in the memory.

(F) If another mode is set, pressing the enter key sets the data set end flag and ends the data input.

(G) In the centering mode, data input is unnecessary.

(Data conversion) (a) In the case of magnification and combination, the shift data is converted into a value obtained by multiplying by a magnification.

(B) For the combination with the trimming mode, see the section on the trimming mode.

(C) Centering data conversion (a) In centering data conversion, a difference (movement amount) between the center of the trimming area and the center of the paper size is obtained.

(B) Addition and subtraction from the trimming data. This allows
Centered trimming data at the same magnification is obtained.

(C) Multiply the above data by a magnification and terminate the data conversion.

(Copy operation) (a) The shift of the Y axis is performed by moving the lens by transmitting shift data to the optical system.

(B) The shift of the X axis is performed by changing the relative position between the image on the drum and the transfer paper.

FIGS. 1 (b-1) and (b-2) are positional diagrams of the related members around the drum in the present invention.

(B-1): When the bias ON of the developing bias roller is located before the slit ON position (slit side) of the registration roller, (b-2): When the bias ON of the developing bias roller is 3 shows a case in which it is located after the resist ON position (on the side of the transfer charger).

In the case of (b-1), the control target is the bias ON timing, and the resist ON timing is a timing delayed by a predetermined amount ( ₁₅ ) of the movement of the photoconductor surface from the bias ON timing.

In the case of (b-2), the control target is the resist ON timing, and the bias ON timing is a timing delayed by a predetermined amount (l ₅ ) of the movement of the photoconductor surface from the resist ON timing.

The control mode for shifting the toner image in the direction of the transfer paper
It has the following four modes.

I. When the shift amount <l ₃ when moving to the left, 1: The time from when the reflected light from the document reaches the photoconductor (when the scanner slit signal is turned on) to when the bias or resist is turned on (reference value) ) Is the shift amount (distance data)
Is reduced by the time converted to time data, and FIG.
In the case of -1), the resist is turned on with a delay of the bias ON and a predetermined amount of time that the photosensitive member surface has moved from the bias ON. Alternatively, in the case of FIG. 1 (b-2), the resist is turned on and the bias is turned on by delaying the photoconductor surface by a predetermined amount of time after the resist is turned on (see C-2, 3 in FIG. 10).

2: Alternatively, the copy start (lamp ON) is delayed from the normal time by the time obtained by converting the shift amount (distance data) into time data, and at the first time (b-1), the bias is turned on and a predetermined amount is exposed from the bias ON. The resist is turned ON with a delay by the time the body surface moves. Alternatively, in the case of FIG. 1 (b-2), the resist is turned on and the bias is turned on by delaying the photosensitive member surface by a predetermined amount of time from the resist ON (see B-2-3 in FIG. 1 (a)).

II. When moving to the left and l ₃ + l ₂ > shift amount> l ₃ , l ₂
Is the distance between the lamp ON and the center of the slit.

1: After the lamp is turned on, in the time when the distance data of [(l ₂ + l ₃ )-(shift amount)] is converted to time data, at the first time (b-1), the bias is turned on and the bias is turned off. Bias delayed by the time the photoreceptor surface moves
It is turned on (see B-2-4 in FIG. 8, B-2-5 in FIG. 9 (a), and B-2-6 in FIG. 9 (b)).

. III left movement, when the shift _{amount> l 3 + l 2, 1} : when the first view (b-1) is to resist ON delayed by the time a predetermined amount photoreceptor surface from the bias ON and bias ON moved . Or, in the case of FIG. 1 (b-2),
The resist is turned on and the bias is turned on with a delay of a predetermined amount of time that the photoconductor surface has moved from the resist ON. And
The lamp is turned on at the time when the distance data of [(shift amount) − (l ₃ + l ₂ )] is converted into time data (B-2-B in FIG. 8).
4, B-2-5 in FIG. 9 (a), B-2--5 in FIG. 9 (b)
6, see Figure 13).

IV. In the case of rightward movement, regardless of the shift amount, the time from when the reflected light from the document reaches the photoconductor (when the scanner slit signal is turned on) to when the bias is turned on or the resist is turned on (reference value) (B-1) after the value obtained by adding the shift amount (distance data) to the time data converted into the time data.
At this time, the resist is turned ON with a delay of the bias ON and a predetermined time from the bias ON by the time when the photosensitive member surface moves. Alternatively, in the case of FIG. 1 (b-2), the resist is turned on and the bias is turned on by delaying the photosensitive member surface by a predetermined amount of time after the resist is turned on (see FIG. 10C-2-3).

As described above, the leftward movement corresponds to three modes. This is because the movement beyond the area, that is, the reference control target is different, so that when the reflected light from the document reaches the photoconductor or when the lamp is turned on, the transport unit stop timing Or the mode according to the difference.

 The above is a brief description of the shift mode.

As described above, in order to perform the trimming and shifting operations, the optical lamp is moved in the Y-axis direction, which is the vertical movement, and the X-axis direction, which is the left and right movement, is between the image on the drum and the transfer paper. This is done by changing the relative position.

Next, the details of the shift mode will be described using a flow.

FIG. 8 is a flowchart of the registration sensor check in the pre-copy operation processing.

When the registration sensor provided near the registration roller is ON, if the conveyance stop timer is not set, the timer is started by setting the conveyance stop timer ON. This is a delay operation for turning off the transport clutch of the transport rollers (27, 28) after the leading edge of the paper collides with the registration roller and creates a slack of about 10 mm. When the time is up, the transfer clutch is turned off, the copy start flag 1 is turned off and the copy start flag 2 is turned off when there is shift data, not rightward movement, and when the shift data is larger than 30 and smaller than 148.
To ON. Copy (lamp ON) by this flag 2
Is executed.

When the shift data is larger than 148, set the bias to O
Set to N and start the resist counter. In addition,
In the present embodiment, the shift data is a shift of 1 mm with respect to one shift data. In addition, hereinafter, in order to simplify the description of FIGS. 9A and 9B, a time converted from a distance such as a shift amount will be described as a shift amount (distance).

FIG. 9 is a flowchart of a shift counter set (B-2-5 in FIG. 9A) and a copy start check 2 (B-2-6 in FIG. 9B) in the pre-copy operation processing. It is.

In the shift counter set of FIG. 9 (a), if shift data is present and the shift is to the left, and the shift data is greater than 30 and less than or equal to 148, the pulse reference is set to a value obtained by subtracting the shift data from 148 and ramping. After confirming that it is ON and confirming that the shift timer set is OFF (not ON), turn on the shift timer and start shift counting. When the shift data is larger than 148, the pulse reference is set to a value obtained by subtracting 148 from the shift data,
After confirming that the bias is ON and not confirming that the shift timer set is ON, the shift counter is started.

As described above, when the shift amount is l ₃ + l ₂ > l ₃ when moving to the left, the bias counter is turned on at (l ₃ + l ₂ ) − (shift amount) from the lamp ON, and the shift counter is turned on to turn on the resist. Start.

Further, when the shift amount is greater than l ₃ + l _2, from the bias ON or resist ON (shift amount) - in (l ₃ + l _2), and starts the shift counter to ON the lamp.

In the copy start check 2 in FIG. 9B, when the shift timer is ON and the shift data is larger than 30 and 148 or less and the shift counter is equal to the pulse reference, the bias is turned ON and the registration counter is set. Start. When the shift data is larger than 148, the copy start flag 1 is turned off and the copy start flag 2 is turned on to execute the copy (lamp ON).

FIG. 1A shows a copy start check (B-2-
It is a flowchart of 3).

In this embodiment, when there is a left shift within 30 mm in the X-axis movement direction, the copy start timing is delayed by the time obtained by converting the shift amount (distance data) into time data. In the copy start check flow, when the copy start flag 1 is ON, the shift data is converted to time data. Next, instead of right shifting, the shift data is 31
When the delay timer is smaller than mm and the delay timer is not turned on, the delay timer set flag is turned on and the delay timer is started.

Next, when the delay timer is equal to the time data, the copy start flag 1 is turned off and the copy start flag 2 is turned on.

Alternatively, the left shift within 30 mm is performed by subtracting the reference value from the slit signal input (see FIG. 10 (a)). Therefore, the start of copying with respect to the paper must be relatively delayed.

Next, a case where the sheet feeding speed and the drum rotation speed are included in FIG. 1 (b-1) will be described.

After the surface of the photoreceptor drum is charged by the main charger, light is incident on the slit and exposed, whereby an electrostatic latent image is generated on the surface of the drum. The distance from the position of the copy start (lamp ON) to the slit on the drum is a distance l ₂ for obtaining a ramp rise time, and a distance l ₃ from the slit as a distance for delaying the copy start by the shift amount to a position where the bias is turned on. , the distance from the bias ON position to the transfer charger l _4, and the distance from the bias ON position to resist ON position and l _5, the distance l ₄ from the transfer charge to bias ON, further (l ₂ + l ₃₎ ×
The position separated by (v _P / v _D ) is the normal start position of the transfer paper. Here, v _P is the sheet feeding speed, v _D is the rotational speed of the drum.

In normal copying (when there is no shift), when copying is started when the leading edge of the sheet reaches the transfer sheet start position, the image and the sheet are efficiently matched by the transfer charger.

During a shift left movement, to copy start from a position is advanced forward by the shift amount l _3. That is, the copy start is delayed by the time obtained by converting the shift amount (distance data) into time data.

That is, in this embodiment, the relative position between the image on the drum and the transfer paper is changed, that is, (a) the copy start is performed based on the bias ON of the developing bias roller or the registration ON timing of the registration roller. The image is moved to the left by delaying the time of (lamp ON). (B) The image is moved to the right by delaying the bias ON of the developing bias roller or the ON timing of the registration of the registration roller with reference to the copy start (lamp ON).

Thus, copy start (lamp ON) and registration
The three modes can be controlled by the relative relationship of ON or bias ON.

The image forming process on the drum is started (exposure lamp ON) a predetermined time before the transfer paper is fed from the supply port and reaches the registration roller. After the scanner that operates as part of the process reaches the predetermined position, the bias is released. Mode to change the time until O or resist ON operation.

When the transfer paper reaches the registration roller, the above process is started, and from that point on, bias ON or registration
Mode to change the time until ON is activated.

In this mode, the resist is turned on or the bias is turned on when the transfer paper reaches the registration roller and a certain amount of slack is formed, and the time from that point until the process is started is changed.

In FIGS. 10 (a) and 10 (b), in the bias control processing indicating the actual operation transmission, if the scanner slit signal is ON and the bias timer (or the registration timer) has not been set yet, the bias timer (or the registration timer) After turning on the timer) set, start the bias timer (or) the resist counter.
Then, the reference value is set to 10 msec. The scanner slit signal is a signal sent to the copier main body when the reflected light from the document reaches the photosensitive member. If there is shift data, the shift data (distance data) is converted to time data. In the case of right shift, the above time data is added to the reference value (that is, bias ON or resist ON
Is further delayed). In the case of the left shift, when the shift data is smaller than 31 mm, that is, within 30 mm, the time data is subtracted from the reference value (that is, the bias ON or the resist ON is earlier). If the timer exceeds the reference value, turn on the bias (or resist) and start the resist counter (or resist pulse). Note that the shift amount is larger than 30 mm, that is, 31 mm
In this case, it is not enough to turn on the bias (or the resist) immediately after the scanner slit signal is turned on.

In Figure 10 (b), the image leading edge reaches the slit portion, usually causes bias ON after t ₃ has elapsed. That is, with l ₃ = 30 mm and t ₃ = 100 msec, the time data obtained by converting the shift data to t ₃ is added or subtracted.

FIG. 13 is a flowchart for turning on the registration clutch (registration ON) for a predetermined time (l ₅ / v _D ), that is, 50 msec after the bias is turned on.

That is, in the registration clutch control, if the bias is ON and the registration counter has passed 50 msec, the registration is turned ON, then the registration counter (registration pulse) is started, and the control is terminated.

Next, the combining mode will be described in detail. The composition mode is
This is a mode in which after copying the first document, the second document is copied on the same side of the copy sheet, and is configured to be able to be performed in a combination mode such as trimming, image shifting, and color.

Compositing mode (mode setting) (b) In the compositing mode setting, set the compositing mode / under color mode or OFF mode. The corresponding mode display on the operation board lights.

(B) After selecting the combination mode or the under color mode, if another mode such as color, magnification, and the number of copies is selected for the paper size, the program mode is set.

FIG. 14 is a processing flowchart of the combination mode setting (A-1-2) in the mode setting processing.

In the composition mode setting, make sure that copying is not in progress (the copying flag is ON when printing is initialized and OFF when copying is completed). If the composition key ON signal on the operation board is turned on at the time of input, the composition key loop Increment the counter by one.
This counter is a counter that is incremented by one each time this flow is executed. In this case, when the loop counter value is larger than 1 and smaller than 40, the key is pressed and released, so that a mode switching process is performed at regular time intervals. Each mode flag is turned ON depending on whether the mode is the undercolor mode or the composition mode, and the corresponding mode display on the operation board is turned on.

Next, the first flag is turned on, and the first display on the operation board is turned on. Turn on the buzzer and execute the composition mode, then turn off the program flag. This flag
This flag is set when the trimming mode or the image shift mode is set after the synthesis mode is set.

 Next, a copy operation in the case of simple composition will be described.

(Copy operation) (a) The sequence from print ON to fixing is the same as the normal copy sequence.

(B) At the path where the fixed paper is discharged, just before reaching the entrance of the intermediate tray gate, the intermediate tray gate claw SOL is turned ON according to the value of the registration counter that was started when the registration was turned ON, and the paper was transferred to the intermediate tray. Lead (C-
2-4).

(C) When the leading edge of the paper has passed the intermediate tray sensor, turn on the intermediate tray set SOL and lift up the intermediate tray set roller.

(D) When the trailing edge of the sheet passes through the sensor, the sheet discharge counter is incremented by one, and the intermediate tray control pulse is started.

(E) With the intermediate tray control pulse, the set SOL is turned off, the intermediate tray set roller is lowered, the sheets are stored in the intermediate tray, and then lifted up again.

(F) For the last sheet of repeat, the intermediate tray control is executed in the end operation processing during the copy end processing to press the sheet pressing plate to prepare for the second sheet feeding.

(G) The second copy is fed by turning on the feed clutch of the intermediate tray.

(H) When the sheet reaches the front of the combining tray gate claw at the leading end of the sheet, the gate claw is opened, and the sheet is turned over and guided to the combining tray.

(I) When the trailing edge of the sheet has passed the combining sensor, a combined sheet supply control pulse is started.

(G) By the above-described pulse control, the sheet that has entered the synthesis tray is sent out to the sheet feeding conveyance path of the sheet feeding unit L in a direction in which the trailing end of the sheet is the leading edge.

(R) The distance where the leading edge of the paper is in front of the registration roller (first
The copy start flag 1 is set at the timing when it reaches the timing shown in B-2-3 in FIG.

(E) When the copy start flag 1 is set, if there is no shift data, the copy start flag 2 is immediately set. If other conditions are satisfied, the process proceeds to the copy routine.

(W) By the above operation, the second copy is performed on the first copied surface, and the combined copy is completed.

FIG. 11 and FIG. 12 are flowcharts of sequence control processes 1 and 2, which are repeat processes in the copy process.

In the sequence control process (see C-2-1 in FIG. 11), when the sequence pulse reaches 10, the exposure lamp is turned on, and when the pulse reaches 40, the optical system start is turned on. Here, a signal (sequence pulse) from a pulse generator linked to the drive motor is counted and controlled. When the optical system start is turned on, a scanner start signal is transmitted to the optical system. The pulse count value is
When the charge reaches 42, the charge is turned ON.

In sequence control process 2 (see C-2-4 in FIG. 12), when the resist pulse (the pulse started by C-2-3 in FIG. 10) reaches 30, the transfer charger is turned on,
When the pulse reaches 45, the separation jam check is performed. When the pulse reaches 210, the fixing jam check is performed. When the pulse reaches 240, the composite mode is turned on and the adder color is turned on.
Or, when the both sides are ON and the first time, the intermediate gate SOL is turned ON. If the leading edge of the sheet is set so as to reach a position short of the intermediate tray gate pawl, the pulse becomes 240.

Further, when the pulse reaches 310, the composite mode is turned ON, the under color is turned ON, or the both sides are turned ON, and the intermediate tray jam check is performed at the first time, and the discharge jam check is performed when the one side is ON. When the pulse reaches 360, a sorter jam check is performed.

Effects As described above, according to the present invention, when the toner image is transferred while being shifted in the traveling direction of the transfer paper, the developing bias is controlled at a timing synchronized with the progress of the transfer paper, so that the toner image on the drum is controlled. It is possible to prevent the background stain on the transfer paper due to the transfer of the value background stain portion outside the image range.

[Brief description of the drawings]

FIG. 1 is a flowchart and positional relationship diagram of a copy start check showing one embodiment of the present invention, FIG. 2 is a sectional structural view of a monocolor copying machine to which the present invention is applied, and FIG.
FIG. 4 is a layout diagram of the operation panel of the copying machine shown in FIG. 4, FIG. 4 is a configuration diagram of the LED array in FIG. 2, FIG. 5 is a block diagram of a control unit in FIG. 2, FIG. FIG. 7 is a flowchart of a pre-copy process and a copy process. FIG. 8 is a flowchart of a registration sensor check in the pre-copy operation process. FIG. 9 is a flowchart of a shift counter set and copy start check 2 in the pre-copy operation process. FIG. 11 is a flowchart of a bias (or registration clutch) control process and a positional relationship diagram in the repeat process. FIGS. 11 and 12 show sequence control processes 1 and 2 in the repeat process, respectively.
13 is an operation flowchart of the registration clutch control, and FIG. 14 is a processing flowchart of the combination mode setting (A-1-2) in the mode setting processing. 1: Copy machine body, 2: ADF, 3: Sorter, 4: Paper feed section, 7: Document set section, 8: ADF paper feed roller, 9: ADF transport belt, 10: Document discharge tray, 11: Contact glass , 16: lens unit, 12: lamp, 13, 14, 15, 17: mirror, 20: photosensitive drum,
21: main motor, 22: main charger, 23: subdivided erase unit, 26: transport roller, 27, 28: transport roller, 29:
Registration roller, 30: separation unit, 33: paper guide,
34: paper discharge roller, 35: cleaning unit.

Claims (2)

(57) [Claims] A developing means for forming a toner image on the latent image carrier and transferring the toner image on the latent image carrier to a transfer paper to form an image; An image forming apparatus for transferring images in a shifted direction, wherein a means for controlling a developing bias at a timing synchronized with the progress of a transfer sheet is provided. 2. An image forming apparatus according to claim 1, wherein said timing control means applies the developing bias with a predetermined time lag with respect to the timing of the advance of the transfer paper. apparatus.