JPS59228672A - Transfer paper conveyance controller of variable power copying machine - Google Patents

Abstract

PURPOSE:To align the front edge of an original image on a photosensitive body to the forward edge of transfer paper by providing a paper feed control circuit which drives a paper feeding means after a prescribed time corresponding to copy magnification after a scanning means starts operating, and a correcting circuit which corrects a prescribed time according to each device. CONSTITUTION:When a copy start switch 34 is turned on, a driving control signal for a photosensitive body driving device 36 is sent out through a sequence controller 33, and while a photosensitive drum starts rotating, a clock pulse generator 31 operates to supply clock pulses to a timing pulse generating circuit 32 and the sequence controller 33. Further, the ON signal of the copy start switch 34 is inputted to the timing pulse generating circuit 32 and the timing pulse generating circuit 32 is driven on the basis of the input time to generate timing pulses for the control signal generation of a platen driving device 37, electrostatic charging corona generator 38, exposure lamp 39, resist roller driving device 40, etc., successively. Those timing pulses are applied to the sequence controller 33 to obtain a control signal for controlling the driving circuit of each device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable magnification copying machine such as an electrophotographic copying machine that projects an original image onto a photoreceptor in the form of a slit and changes the magnification to a plurality of magnifications including equal magnification to form a copy image. The present invention relates to a transfer paper conveyance control device.

Generally, a slit scanning type electrophotographic copying machine is constructed as shown in FIG. That is, in FIG. 1, reference numeral 1 denotes a photosensitive drum constituting a charge holding body. When the copy start button is pressed, the drum 1 is rotated in the direction of the arrow, and the residual charge is removed by uniform exposure by the static elimination lamp 2. After being erased, it is uniformly charged by the corona charger 3. A document 4 to be copied is placed on a movable document table 5 and starts moving in the direction of the arrow at a speed equal to the circumferential speed of the photoreceptor drum 1. The image is projected onto the photoreceptor drum 1 through the lens 8, thereby forming an electrostatic latent image on the photoreceptor drum 1 corresponding to the original image.

This electrostatic latent image is formed into a toner image by the developing roller of the toner developing device 9. On the other hand, the transfer paper 10 is fed out from the cassette by the paper feed roller 11, and the registration roller 1
2, the toner image on the photosensitive drum is conveyed again toward the transfer point in time with the timing when the toner image reaches the transfer point, and at the transfer point, the toner image and the leading edge of the transfer paper 10 are brought into contact with each other. The toner image is superimposed on the transfer paper 10 so as to match, and is transferred to the transfer paper 10 by the action of the transfer corona charger 13. The transfer paper 10 on which the toner image has been transferred is peeled off from the photoreceptor drum 1 by the action of the peeling corona charger 14, then sent to the fixing roller 15 where the toner image is fixed, and then transferred to the copy tray 16 by the discharge roller. It is configured to be discharged.

In order to obtain variable-magnification copies in a slit-scanning copying machine with such a configuration, when the photoreceptor drum is moved at a constant speed, the slit scanning speed must be changed to the slit scanning speed for full-size copying/variable-magnification line. It is necessary to change only the ratio, and to move the lenses and mirrors of the optical system for optical path correction during variable magnification copying.

By the way, in general, in a slit scanning type copying machine, when performing an exposure process, in order to prevent the influence of vibrations of the document table and mirror at the time of startup, before the start of exposure, as shown by α in FIG. This requires a so-called run-up run in which the original or mirror is moved or scanned a certain distance in advance, and when making full-size copies, the moving speed of the photoreceptor drum and the slit are usually adjusted as described above. The scanning speeds are made to match, so that the leading edge of the original image formed on the photoreceptor and the leading edge of the copy sheet, which is also fed at the same moving speed, coincide.

Therefore, if a variable magnification copying mechanism is simply incorporated into a slit scanning copying machine configured as described above, the run-up time during variable magnification copying will change as the slit scanning speed changes, and the The leading edge of the exposed original image fluctuates and does not match the leading edge of the transfer paper, resulting in transfer misalignment.

Conventionally, as a control means for matching the leading edge of the copy image on the photoreceptor and the leading edge of the transfer paper each time the copying magnification is changed, for example, (1) two detectors are arranged and the actual A method of reading the original transport speed, predicting the projection start position by calculation, and transporting the transfer paper. (2) One detector determines the clock start timing, and each timer is different for each magnification. Other known methods include (3) a method of changing the time point at which the transfer paper is fed, and (3) a method of providing a different detector for each 0 magnification and starting conveyance of the transfer paper by the operation of the detector. However, although method (1) has the advantage of accurately determining the timing of paper feeding based on the actual transport speed of the document, it requires at least two detectors;
In addition, method (2) requires one detector and multiple timers, and method (3) also requires multiple detectors, so no matter which method is applied, the device is There are drawbacks such as complexity and difficulty in adjustment.

The present invention has been made in order to eliminate the above-mentioned drawbacks in the conventional transfer paper conveyance control device of a variable magnification copying machine, and is capable of aligning the leading edge of a document image on a photoreceptor with the leading edge of a transfer paper using a simple configuration. It is an object of the present invention to provide a transfer paper conveyance control device.

In general, in copying machines, the moving speed of the document table or the scanning means consisting of the optical system in the run-up section is not only not constant, but also varies from machine to machine, and the run-up distance itself also differs from machine to machine. However, once the device is specified, it is thought that there will not be much variation in individual copy operations. Focusing on this point, the present invention does not use a separate detector or a timer activated by the detection signal, and instead prints data after a predetermined time period corresponding to the copying magnification has elapsed after the scanning means starts operating. A paper feeding control circuit for driving the paper means and a correction circuit for correcting the predetermined time for each device are provided so that no transfer deviation occurs at the transfer point regardless of changes in copy magnification. be.

The present invention will be described in detail below based on Examples.

FIG. 2 is a schematic configuration diagram for explaining the operation mode of an embodiment of the present invention. In Fig. 2, 21 is a photosensitive drum that rotates at a constant circumferential speed regardless of changes in the copying magnification, and 22 is a movable document table. When the linearization rate is m, it can be moved at a speed of V/m. Reference numeral 23 denotes an original placed on the original table 22, Sae is an exposure lamp, 25 is a projection lens, 26 is a registration roller that is driven to rotate at a circumferential speed ■ after a predetermined period of time has elapsed after the original table 22 starts moving, 27 28 is a registration roller drive circuit, and 29 is a control circuit for controlling the drive circuit.

Note that Pl is the document projection point z2 on the photosensitive drum 21, the transfer point, Q is the exposure position, and a is the distance between the leading edge 23' of the document 23 placed on the document table 22 at the home position and the exposure position Q. L is the length between the document projection point P1 and the transfer point P2 of the photosensitive drum 21, and b is the distance from the registration roller 26 to the transfer point PzJ.

In the transfer paper conveyance control device of the copying apparatus configured as described above, when a copy start button (not shown) is turned on, the photosensitive drum 21 rotates in the direction of the arrow at a circumferential speed of ■ during full-size copying. The document table 22 starts moving in the direction of the arrow at a speed 2, passes through a run-up distance a, and when the leading edge 23' of the document 23 reaches the exposure position Q, exposure of the document is started.

On the other hand, the transfer paper 26 is pressed when this copy start button (7) is turned on.
By operation, the paper is fed by a paper feed roller (not shown),
It hits the registration roller 26 and temporarily waits at that position.

If the circumference of the photoconductor drum 21 is long from the original projection point P1 to the transfer point P2, the distance from the registration roller 26 to the transfer point P2 is normally
Since the distance from the front edge of the document is longer than the
3' reaches the exposure position Q and the exposure starts,
The photosensitive drum 21 advances along the length L-b) of the difference,
When the leading edge of the projected image of the document reaches point P'1, the control circuit 2 is connected to the drive circuit path for driving the registration rollers 26.
9, the registration rollers 26 are rotationally driven at that point, and the transfer paper 27, which has been on standby, is conveyed toward the transfer point P2.

Therefore, the leading edge of the projected image of the original changes from point P'1 to transfer point P2.
The distance from the registration roller 226 to the transfer point P2 is the same, and the circumferential speeds of the photoreceptor drum 21 and the registration roller 26 are also the same, so at the transfer point P2, the developed document projection image is The leading edge and the leading edge of the transfer paper 27 will match.

That is, after the document table 22 starts moving, the leading edge 2 of the document 23
3' passes the run-up distance a and reaches the exposure position Q, and the time a/V required for document exposure to start and the leading edge of the document projected image on the photoreceptor drum reaches point P'1. The time required for (L-b)/V, i.e., a/V
After the time determined by 10(L-b)/V has elapsed, the drive circuit 28 of the registration roller 26 is activated to align the leading edge of the original image on the photosensitive drum with the leading edge of the transfer paper. can.

Generally, when copying at a copying magnification of m, the document table 22 is moved at a speed of V/m, so that the leading edge 23' of the document 23 on the document table passes the run-up distance a and reaches the exposure position Q. The time required is ma/y. Therefore, when copying at a copying magnification of m, after the copying operation is started and the document table 22 starts moving, if the registration roller 26 is driven after the elapse of the time determined by ma/V + (L-b)/V, Similarly to the same size copying, the leading edge of the developed document projection image and the leading edge of the transfer paper 27 can be aligned at the transfer point P2.

In the above embodiment, the circumferential length of the photosensitive drum 21 from the document projection point P1 to the transfer point P2 is the same as that of the registration roller 2.
Although the driving start point of the registration row 226 is shown as being longer than the distance from the transfer point P2 to the transfer point P2, if the circumferential length and the distance are set to be equal, this driving start point is of course Since it is about , it becomes ma/■.

Figures 3 (5) and (B) show the results during full-size copying and variable-magnification copying (
3 shows a timing chart of the operation of each part of the copying process at a variable magnification ratio m). To explain the timing chart for same-size copying shown in FIG. Pass through the manuscript 2
At time t1 when the leading edge 23' of the document 3 reaches the exposure position Q, exposure of the original starts. After the start of exposure, a time determined by (L-b)/V has elapsed, and at time t2 when the leading edge of the projected image of the document formed on the photosensitive drum reaches point P'1, the drive circuit for the registration row 226 is activated. A control signal is generated to 28, the registration rollers 26 are rotated, and conveyance of the transfer paper 27 is started.

During variable-magnification copying, the time required to move the run-up distance a changes by +71 a/v, so the exposure start time and the generation time of the registration roller drive control signal based on it change by ``%'' 2K, respectively. .

By the way, in each device, the above ma/V +
Even if the time determined by (L-b)/v is uniformly determined and the generation point of the drive control signal for the registration roller 26 is set, as described above, in many devices that have actually been completed, The speed of the document table during the run-up period, the run-up distance, etc. vary, and there are slight differences between devices, so transfer misalignment may occur at the transfer point. It may be necessary to correct the time taken.

In the present invention, in order to deal with this, ma/V
It is equipped with a correction circuit that corrects the value. By providing a correction circuit in this way and correcting the ma/■ value as necessary for each device, the leading edge of the original image on the photosensitive drum and the leading edge of the transfer paper can be accurately aligned at the transfer point P2. be able to.

Next, FIG. 4 shows a block diagram of a configuration example of a control circuit of the transfer paper conveyance control device of the present invention including this correction circuit. In FIG. 4, 31 is a clock pulse generator which divides the circumferential length of the photosensitive drum 21 and generates pulses synchronized with its rotation; 32 is a clock pulse from the clock pulse generator 31; A timing pulse generation circuit receives a copy start signal and forms a predetermined timing pulse, 33 is a sequence controller, a copy start switch 34 and other input devices 3.
5 and timing pulses from the timing generation circuit 32, the photoreceptor drive device 36, document table drive device 37, charged corona generator 38, exposure lamp 39,
Registro T drive device 40 and other drive systems 41
A drive control signal is sent to each drive circuit 42 such as. 43 is a variable-magnification copy designation switch, and 44 is a variable-magnification copy designation switch at each magnification copy specified by the variable-magnification copy designation switch 43;
This is an arithmetic circuit that calculates the ma/V+(L-b)/V value in order to determine the starting point of rotational drive of the registration roller 26, and the arithmetic output is configured to be input to the timing pulse generation circuit 32. .

Reference numeral 45 denotes a correction circuit for correcting the ma/■ value in the arithmetic circuit 44.

In the control circuit configured as described above, when the copy start switch 34 is turned on, a drive control signal for the photoconductor drive device 36 is sent via the sequence controller 33, and the photoconductor drum starts rotating. At the same time, the clock pulse generator 31 operates and supplies clock pulses to the timing pulse generation circuit 32 and the sequence controller 33. Also, copy start switch 3
The ON signal No. 4 is input to the timing pulse generation circuit 32, and based on this input signal, the -timing pulse generation circuit 32 is driven based on that point in time, and the document table driving device 37, charging corona generator 38, and exposure lamp 39 are driven. , the registration roller drive device 40, etc., and sequentially generates timing pulses for generating control signals for each drive circuit. Each of these timing pulses is applied to the sequence controller 33 and becomes a control signal for controlling the drive circuit 42 of each device. The points are driven sequentially.

The above is the operation for same-size copying, but for variable-magnification copying, the variable-magnification copy designation switch 43 is operated to specify the variable magnification ratio. This magnification ratio designation signal calculates the timing to start driving the registration roller in the arithmetic circuit material, and the output signal determines the time point at which the timing pulse for driving the registration roller at the same magnification, which is generated by the timing generation circuit 32, is generated. is changed at the time of variable-magnification copying. In addition, as mentioned earlier, the length of the run-up distance a and the run-up distance a
The average speed at which the leading edge of the document passes varies between individual devices. In order to prevent transfer misalignment, correct the In a/v value for each device.

Although the embodiment described above is applied to a copying machine with a movable document table, the present invention can be similarly applied to a copying machine with a movable optical system.

As described above in detail based on the embodiments, the present invention provides a transfer paper conveyor that generates a control signal for driving the transfer paper conveyor after a predetermined time period corresponding to the copying magnification has elapsed after the start of the operation of the scanning means. comprising a control circuit and a correction circuit for correcting fluctuations in the predetermined time due to device variations,
The transfer paper conveyance control device is configured so that no transfer deviation occurs at the transfer point regardless of changes in copy magnification, so changes can be made with a simple configuration without using a separate detector or a timer activated by it. The original image on the photoreceptor can be aligned with the leading edge of the transfer paper during double copying. Furthermore, effects such as the ability to easily adjust transfer deviations caused by variations in devices can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the configuration of a conventional electrophotographic copying machine, FIG. 2 is a schematic diagram of an embodiment of the present invention, and FIG. FIG. 4, which is a timing chart showing the operation of each part in the copying process of the illustrated apparatus, is a block configuration diagram of an example of the configuration of the control circuit of the transfer paper conveyance control apparatus according to the present invention. In the figure, 21 is a photosensitive drum, 22 is a document table, and 23
C N document, 26 is the registration roller, 27 is the transfer paper, part is the registration roller drive circuit, 29 is the registration roller drive control circuit, Pl is the original projection point, P2 is the transfer point, Q is the exposure position, and a is the run-up distance. show. Patent applicant: Olympus Optical Industry Co., Ltd. Figure 1 Figure 2 Figure M3 (A) (B)

Claims (1)

[Claims] In a variable magnification copying machine, a copy document is scanned by a scanning means that varies the scanning speed depending on the copy magnification, and copy images of multiple magnifications are formed on a photoreceptor that moves at a constant speed. The magnification is m, the approach distance of the scanning means is a,
L is the length from the photoconductor's original projection point to the transfer point, B is the distance from the transfer paper conveyance means to the transfer point, and is the scanning speed during full-size copying, the moving speed of the photoconductor, and the transfer paper conveyance speed. ②, after the scanning means starts operating, ma/V0(L
-b) A transfer paper conveyance control circuit that generates a control signal for driving the transfer paper conveyance means at a timing determined by /V, and a correction for correcting fluctuations in the above ma/■ value due to device variations. 1. A transfer paper conveyance control device, comprising a circuit, and configured to align the leading edge of a document image on a photoreceptor with the leading edge of a transfer paper at a transfer point, regardless of changes in copying magnification.