JPS61158343A - Automatic double face copying device - Google Patents

Abstract

PURPOSE:To form an accurate binding margin without providing a specific sensor by obtaining a paper feeding timing based upon a registration roller for feeding transfer paper to a photosensitive body on the basis of an inversional signal for a motor for driving an optical system. CONSTITUTION:The rotation of the motor for the optical sensor is detected by an encoder. The turning direction of the motor, whether the motor is inverted or not, and whether the motor is inverted from a direction A to a direction B or inverted in the reverse direction can be detected by detecting a signal from an output terminal Q. Thereby, a reference point of an exposing light source 3, i.e. the inversional timing from the backward course to the forward course, can be detected by the output of the encoder. If it is defined that the rotation of the direction A is the backward course of the optical system and the rotation of the direction B is the forward course, the detection of the inversion from the direction A to the direction B is the inversional timing of the reference point. A timer or the like is triggered on the basis of the inversional timing and the registration roller 12 is driven by the output of the timer, so that the binding margin having a sufficient width can be formed without exerting influence upon the braking state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automatic double-sided copying apparatus that can obtain accurate binding white when transferring an image.

(Prior Art) A general copying apparatus is schematically shown in FIG. Place original 2 on the surface of platen glass 1, then close the platen cover (
(not shown) and operates the copy start key, the exposure light source 3 exposes and scans the original 2 in the direction of arrow a, and the light image of the original 2 passes through the mirror 4.5 for image formation. The light is guided to the surface of a photosensitive drum 6 as a photosensitive member. The photosensitive drum 6 is a grounded metal cylinder with a photoconductive layer made of selenium or the like provided on the outer peripheral surface thereof, and rotates in the direction indicated by the arrow in conjunction with the exposure scanning.

Before the arrival of the optical image on the photosensitive drum 6, the photoconductive layer is, for example, uniformly charged by a charging electrode 7 to which a DC high voltage is applied, and the photoconductive layer in this state receives the optical image. Then, the conductivity of the area that receives the light increases, and the electrical charge in that area escapes to the metal cylinder, and positive charges remain in the dark area depending on the degree of brightness, and this causes the photoconductive layer to An electrostatic latent image corresponding to the image of the original is formed on the surface of the document.

When the portion on which this electrostatic latent image is formed reaches the developing sleeve 8a of the developing device 8, the negatively charged developer is attracted to the remaining positively charged portion of the photosensitive drum 6 by electrostatic force. Ru. As a result, a developer image corresponding to the electrostatic latent image is formed on the surface of the photosensitive drum 6.

The transfer paper 10 in the paper feed cassette 9 is sent out in the direction of the registration roller 12 by the feed roller 11 and once stopped, and the leading edge of the transfer paper matches the leading edge of the developer image on the photosensitive drum 6. At such timing, the developer image on the surface of the photosensitive drum 6 is transferred by the transfer pole 13 to which a direct current high voltage is applied to the transferred transfer paper.

Thereafter, the transfer paper is separated from the photosensitive drum 6 by the separation electrode 14 to which AC high voltage is applied, and is sent to the fixing device 16 by the general conveyance belt 15, where the developer image is fixed.
is discharged.

Reference numeral 18' denotes a removing electrode for removing charges remaining on the photosensitive drum 6, and reference numeral 19 denotes a cleaning device for removing developer remaining on the surface of the photosensitive drum 6.

FIG. 2 shows the shelf layout of an automatic double-sided copying apparatus. ■
. . . indicates the transfer path of the transfer paper 10. Further, the Δ mark indicates the side to which the image has been transferred. First, in the case of the first copy, the transfer paper 10 fed from the paper feed cassette 9 is fed in the direction of the photosensitive drum 6 at the right timing by the registration roller 12, and the developer image is transferred. After passing through the conveyor belt 15 and the fixing device 16, the transfer paper 10 proceeds in the opposite direction, and the front and back sides of the transfer paper 10 are reversed by the conveyor belt 20 and the guide 21.
In that state, it is dropped onto the stack 22, and the feed roller 23
The paper is fed again to the registration roller (2) by other rollers (not shown). and,
When the photosensitive drum 6 carrying the image of the next document rotates by a predetermined angle, the registration roller 12 is driven, and the transfer paper with its front and back reversed is conveyed to the transfer pole 13, where the image is transferred, and the image is transferred to the conveyor belt 15. and via the fixing device 16 ■
In this way, in an automatic double-sided copying apparatus, images of original documents (same or different) are automatically transferred to one sheet of transfer paper on both sides. Note that if only one side of the copy is made during such an automatic duplex copying operation, in order to align the pages of the transfer paper stacked on the tray 17, the path is changed so that the transfer paper of the single-sided copy is turned over. It is routed through ■′■′■′.

By the way, in such an automatic double-sided copying apparatus, the driving timing (paper feeding timing) of the registration roller 12 for feeding the transfer paper toward the photosensitive drum 6 is set to the third timing.
As shown in the figure, using the detection signal of the brake sensor on the return trip as a reference, or using a special paper feed sensor to detect this on the outward trip, and using this detection signal as the reference,
Furthermore, a home position sensor for detecting a reference point is specially provided, and the detection signal is used as a reference for setting.

However, if the detection signal from the brake sensor is used as a reference, and the detection signal is used as a trigger signal to operate the timer, the optical system feed is quite unstable during brake operation, so the set optical system The transfer amount may not match the timer setting value, and the registration drive timing becomes inconsistent. As a result, variations occur in the amount of binding white (image shift), making it impossible to obtain a good double-sided copy image.

On the other hand, when using the detection signal from the paper feed sensor as the reference,
This detection occurs after the optical system has reversed at the reference point, so it has come out of the braking state and there is no instability factor, but because the timing of obtaining the detection signal is too late, a sufficient amount of binding white In some cases, it may not be possible to obtain a paper feed sensor, and it may also be necessary to provide a special paper feed sensor.

Furthermore, when the detection signal from the home position sensor is used as a reference, it is not affected by instability during braking compared to the above two types of cases, and since the detection time is relatively early, it is possible to ensure that the amount of stapling is sufficient. Although it is possible to do so, there is still a problem in that it is necessary to provide a special home position sensor.

(Object of the Invention) The present invention has been made in view of the above points, and its purpose is to enable the registration roller to be driven at accurate timing without providing a special sensor as described above. An object of the present invention is to provide an automatic double-sided copying device that can form accurate binding whites.

(Structure of the Invention) For this purpose, the automatic double-sided copying apparatus of the present invention obtains the paper feeding timing by the registration roller that sends the transfer paper to the photoreceptor based on the reversal signal of the motor that drives the optical system. .

(Example) Examples of the present invention will be described below. Exposure light source 3
A DC motor is used as a drive source for scanning the image below the document table glass 1, and the motor is controlled by, for example, PLL control. Therefore, in the present invention, the rotation of the motor of this optical system is detected by an encoder.

For example, as shown in FIG.
1a, and a 211M optical sensor 32.33 with a phase difference of 90 degrees is provided to detect the hole 31a, and the detection signal from the sensor 32.33 is sent to the waveform shaping circuit 34.
．． Shaped into a rectangular wave at 35, and then connected to a D-type flip-flop 36.
It is configured so that it can be input.

In this encoder, when the rotary plate 31 rotates in the direction of arrow A, the pulse input to the clock input terminal rCJ of the flip-flop 35 is delayed by 90 degrees in phase from the pulse input to the data input terminal D-1, so the output terminal The rQJ signal becomes high level, and if it rotates in the direction of arrow B, the pulse input to the clock input terminal "C" advances 90 degrees, so the output &
The signal of 1MrQJ becomes low level (FIG. 5).

Therefore, by detecting the signal at the output terminal rQJ, it is possible to detect the rotation direction of the motor and whether or not it has been reversed, as well as whether it has reversed from input direction rotation to B direction rotation or vice versa. can.

Therefore, the reference point of the exposure light source 3, that is, the return path -
The inversion timing on the outward path (hereinafter simply referred to as inversion timing) can be known from the output of the encoder described above.

For example, if the incoming direction rotation is the return path of the optical system, and the B direction rotation is the similar outgoing path, if a reversal of the B direction rotation from the A direction rotation is detected, this becomes the reference point reversal timing. The detection time point of this reversal timing is the same timing as the detection time point by a conventional home position sensor.

Therefore, if a timer or the like is triggered by the timing signal using this inversion timing as a reference, and the registration roller 12 is driven by the output of the timer, it will not be affected by the brake state and a sufficient amount of stapling will be achieved. It becomes impossible to form white.

FIGS. 6 to 8 are for double-sided copying.

First, FIG. 6 shows a case where a single-sided original is copied on both sides. Transfer paper 1 that is a copy of a single-sided original 2A having a character portion 2A2 named rFJ with a binding white 2A+ formed on the left side.
0A has a copy image (binding white 10A+, character part 1'0A2) formed on its top surface, and the route ■ shown in Figure 2 is
~■ are transported (Fig. 6(a)). Then, it is turned over by the conveyor belt 20 and the guide 21, and the next one-sided original 2B is set and stands by until the start of copying (FIG. 6(b)). This single-sided original 2B has a binding white 2B+ formed on the left side, similar to the single-sided original 2A described above.
There is a character part 2B2 named "P". Then, on the back side of this reversed transfer paper 10A, there is a binding white 10 on the right side of the front side.
The character portion 2B2 of the original 2B is transferred so that the same binding white as A1 remains (FIG. 6(C)). Therefore, the registration roller 1 in the case of copying this one-sided original 2B
The drive timing of No. 2 is delayed by an amount corresponding to the binding white 2B+ compared to the timing when copying the document 2A. In this way, the drive timing of the registration roller 12 is different when copying on the front side of the transfer paper 10A and when copying on the back side, but even in this case, the drive timing is set based on the motor reversal timing. This allows accurate binding whiteness to be obtained.

FIG. 7 shows a case where a double-sided original such as a book is to be copied on both sides. The above double-sided document 2C has a character portion 2B2 rFJ with a binding white 2C+ formed on the right side on one side, and a character portion 2C “P” with a binding white 2C3 formed on the other side on the left side. Transfer paper 10B with one side copied
has a copy image (binding white 10B+, character part 10) on the top surface.
In the state in which B2) is formed, it is conveyed along the routes (1) to (2) shown in FIG. 2 (FIG. 7(a)). And the conveyor belt 20
is reversed by the guide 21, and its front and back sides are reversed, and the above-mentioned double-sided original 2C is set with the front and back sides reversed and waited until the start of copying (Fig. 7 (bl)).The other side of this original 2C is A binding white 2C1 is formed on the opposite left side.Then, on the reverse side of the reversed transfer paper 10I3,
The character portion 2C on the other side of the double-sided original 2C is copied so that a binding white similar to the binding white 10B+ on the front side remains on the left side thereof (FIG. 7(C)). Therefore, the drive timing of the registration roller 12 in this case is
The timing is the same as the timing when copying the above one side of C.

FIG. 8 shows another example of duplex copying of a single-sided original. Character part 2 “F” with binding white 2D+ formed on the right side
The transfer paper 10G on which the single-sided original 2D having the size D2 was copied is
The copied image (binding white 10C1, character part 10C2) is printed on the top surface.
) is conveyed through the paths ■ to ■ shown in Figure 2 (Figure 8 (al)).Then, it is reversed by the conveyor belt 20 and guide 21, and its front and back are reversed, and the next A single-sided original 2E is set and waited until copying starts (FIG. 8(b)).This single-sided original 2E is similar to the single-sided original 2D
Similarly, it has a character portion 2E2 rPJ with a binding white 2B+ formed on the right side. Then, the above-mentioned inverted transfer paper 10
The character portion 2E2 of the document 2E is copied on the back side of G so that a binding white similar to the binding white 10C1 on the front side remains on the left side thereof. Therefore, the drive timing of the registration roller 12 when copying this single-sided original 2E is different from the timing when copying the original 2D.
Speed up by the amount corresponding to El. In this way, when speeding up the registration drive timing, it is extremely effective to utilize the motor reversal timing.

It may not be possible to obtain a detection signal using a conventional paper feed sensor as a reference.

(Effects of the Invention) As described above, in the automatic double-sided copying apparatus of the present invention, the paper feeding timing by the registration roller that feeds the transfer paper to the photoreceptor is obtained based on the reversal signal of the motor that drives the optical system. Therefore, the registration roller can be driven accurately without providing a special sensor, and accurate binding white can be formed.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an electronic copying device, FIG. 2 is a schematic explanatory diagram of an automatic double-sided copying device, FIG. 3 is an explanatory diagram for obtaining a reference signal for the conventional drive timing of a registration roller, and FIG. A configuration diagram of an encoder for obtaining a reversal signal of the motor according to an embodiment of the present invention, FIG. 5 is a timing chart of the operation of the encoder, and FIGS. It is an explanatory diagram. 1...Platen glass, 2.2A, 2B, 2C. 2D, 2E...Original, 3...Light source for exposure, 4.5.
...Mirror, 6...Photosensitive drum, 7...Charging electrode, 8
. . . Developing device, 9 . . . Paper feed cassette, 10. IOA
~IOC...Transfer paper, 11...Feeding roller, 12.
...Registration roller, 13...Transfer pole, 1
4... Separation electrode, 15... Conveyor belt, 16... Fixing device, 17... Receiver is plate, 18... Eliminating electrode, 19...
...Cleaning device, 20...Transport belt, 21.
... Guide, 22 ... Stack, 23 ... Feed roller, 31 ... Rotating plate, 31a ... Hole, 32.33.
・・Optical sensor, 34. 35 ・・Waveform shaping circuit, 36
...D type flip-flop.

Claims (2)

[Claims] (1) In an automatic double-sided copying device that transfers images of the same or different originals obtained by an exposure scanning optical system onto both sides of the same transfer paper, the paper feeding timing by the registration roller that feeds the transfer paper to the photoreceptor is An automatic double-sided copying apparatus characterized in that a reversal signal of a motor that drives the optical system is obtained as a reference. (2) The paper feeding timing is set based on a reversal point at the starting end of the optical system obtained by an encoder that detects the rotation of the motor. Automatic double-sided copying machine.