JPH05229683A - Device for separating feed paper - Google Patents

Abstract

PURPOSE:To prevent folding of paper at separating portions while maintaining the performance of a paper separating device in separating sheets of paper which overlap as they are fed. CONSTITUTION:A device for separating paper fed is provided which has a pair of separation rollers 7 comprising a normal rotation roller 5 which is disposed inside a paper feed passage in which sheets of paper are conveyed at regular intervals and which is driven at fixed intervals in order to separately feed the sheets of paper carried in and a reversing roller 6 which is started to be driven synchronous with the normal rotation roller 5; and a paper detection means 23 disposed in proximity to the paper-feed downstream side of the pair of separation rollers 7 to detect the presence of paper at the position of the pair of separation rollers 7. A drive control means is provided which stops driving of the reversing roller 6 when the paper detection means 23 detects the change from the presence to the absence of paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sheet conveyance in an image forming apparatus such as a copying machine or a printer, and more particularly to a multifeed sheet separating apparatus.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a printer is known which prints addresses and the like sequentially output from a data storage unit such as a personal computer. In this type of image forming apparatus, the transfer paper fed out from the paper feed cassette is separated in the middle, and then the toner image formed on the photoconductor is transferred to form an image. There is.

In the conventional apparatus shown in FIG. 6, transfer sheets are transferred from the paper feed cassettes 101 and 102 to the paper feed rollers 103 and 102.
It is fed out by 104 and conveyed to a separating roller pair 107 composed of a forward rotation roller 105 and a reversing roller 106. When the reversing roller 106 is pressed against the forward rotation roller 105 side with a required pressure and has a torque limiter between the shaft and the roller, when a reverse torque of a predetermined value or more acts. It is designed to spin idle.

That is, the torque limiter is used when the transfer sheet is not conveyed or when one sheet of transfer sheet is conveyed.
6 is set so as to rotate idly, whereby the reversing roller 106 is configured to convey the transfer sheet around the forward rotation roller 105. Further, as shown in FIG. 7, when the transfer sheets are fed from the sheet feeding cassettes 101 and 102 in a double-feeding manner, the double-feeding transfer sheet on the side of the reversing roller 106 receives the force in the opposite direction by the reversing roller 106 and is separated. Then, only one transfer sheet on the side of the forward rotation roller 105 is conveyed.

[0005]

In the above-mentioned conventional sheet conveying apparatus, the double-fed transfer sheet is transferred by the reversing roller 106.
The sheet is fed back to the position immediately before the nip between the forward rotation roller 105 and the reversing roller 106 and stands by. During this time, the tip end thereof is in contact with the reversing roller 106 being driven.
Paper breakage may occur at the tip. Then, there is a fear that this paper break may cause a jam, or may cause a transfer not being properly performed in a printer or the like.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a conveying paper separating device which prevents the occurrence of paper folding at the separating portion while maintaining the separation performance for double-fed paper. And

[0007]

In order to achieve the above-mentioned object, the present invention is arranged in a paper transport path for transporting at a constant interval, and at each of the above-mentioned constant intervals in order to separate and carry out a sheet to be loaded. A separating roller pair composed of a normal rotation roller driven in the direction of and a reverse roller starting to drive in synchronization with the normal rotation roller, and a separation roller pair disposed adjacent to the separation roller pair on the downstream side in the sheet conveying direction. In a conveying paper separating device having a paper detecting means for detecting the presence / absence of paper at a position, a drive control for stopping the driving of the reversing roller when the paper detecting means detects a change from the presence of paper to the absence of paper. It is a structure provided with means.

[0008]

According to the present invention, when the sheets are double-fed, they are separated by the pair of separating rollers and only one sheet is normally conveyed.
The double feed sheet remains between the forward rotation roller and the reverse rotation roller of the separation roller pair, and in this state, the driving of the forward rotation roller is stopped. On the other hand, the reversing roller is driven, so that the reverse feeding of the double-fed sheet is started. Then, the driving of the reversing roller is stopped at the time when the double feed sheet is fed back until it is no longer detected by the sheet detecting means. By stopping the driving of the reversing roller, no force acts on the leading edge of the double-fed paper.

[0009]

2 is a sectional view showing a schematic structure of an image forming apparatus to which the present invention is applied. The image forming apparatus includes a paper feed cassette 1 for normal paper, a paper feed cassette 2 for parallel paper feed, a first separation roller pair 7 including paper feed rollers 3 and 4, a forward rotation roller 5 and a reverse roller 6, Rolling roller 8 and reversing roller 9
The second separation roller pair 10 and the registration roller pair 1
1, a photoconductor 12, a charging device 13 disposed around the photoconductor 12, an image forming unit (not shown), a light emitting unit 14 including a laser optical unit for printing, a polygon mirror 1
5, a transfer roller 16, a fixing roller pair 1 including a heating roller, etc.
7, a pair of discharge rollers 18, 19, a discharge guide 20, a discharge tray 21 and the like. As shown in FIG. 3, the paper feed cassette 2 includes two rows of transfer paper aligning units 2 inside.
a and 2b are provided in parallel.

Further, the image forming apparatus has transfer paper sensors 22 and 22 'for detecting the presence / absence of the transfer papers in the paper feed cassette 1 and the transfer paper alignment units 2a and 2b, and detects the double feeding of the transfer papers. First double feed sensor 23, second double feed sensor 24, registration sensor 25 for driving timing of registration roller pair 11, timing sensor 26 for light emission start timing by light emitting unit 14, and ejection for detecting ejection of transfer sheet Each sensor such as the sensor 27 is included. The detection units of these sensors can detect the transfer sheets fed in parallel.

In the image forming apparatus having the above-described structure, the transfer sheets in each row of the sheet feeding cassette 2 are fed out by the sheet feeding roller 4 in synchronization, and are sequentially arranged side by side by the second separating roller pair 10. After being conveyed, it passes through the first separating roller pair 7 and comes into contact with the registration roller pair 11. In addition,
At the time of feeding from the paper feeding cassette 2, the reversing roller 6 is idled so that the transfer sheet that has passed through the second separating roller pair 10 can pass smoothly as it is. This drive switching of the reversing roller 6 is discriminated and controlled by data from a 4-bit cassette information section 30 in which a magnet or the like is attached to a required bit formed in the front portion of the sheet feeding cassette 2 as shown in FIG. Alternatively, it is controlled depending on whether or not the paper feed cassette 2 is selected by a manual instruction. The registration roller pair 11 is driven and controlled based on a signal from the registration sensor 25.

After that, when the registration roller pair 11 starts to carry out the transfer sheet and a signal is output from the timing sensor 26, the photosensitive member 12 is driven based on this output signal and the outside of the image forming apparatus is driven. Alternatively, the image signal input from the data storage section of the data storage medium set at a proper position of the device is optically modulated and the light emitting section 14 emits modulated light (laser light).
And the photoconductor 12 is exposed by the laser beam through the polygon mirror 15. The photoconductor 12 may be driven at the start of driving the paper feed roller 4. Then, the photoconductor 12 is formed in parallel by the image forming means in the axial direction of the photoconductor 12. That is, the surface of the photoconductor 12 is charged by the charging device 13, an electrostatic latent image is formed in parallel with the charged area by the above exposure, and is visualized as a toner image by a developing device (not shown). The toner image is transferred to each transfer sheet by the transfer unit 16, fixed by the fixing unit 17, passed through the discharge guide 20 by the discharge roller pair 18 and 19, and discharged to the discharge tray 21.

Further, the transfer paper in the paper feed cassette 1 is fed by the paper feed roller 3, sequentially conveyed one by one by the first separating roller pair 7, and abuts on the registration roller pair 11. Then, the subsequent operations are the same as those described above except those related to the parallel sheet feeding.

Next, the configuration of the control system in one embodiment of the image forming apparatus to which the present invention is applied will be described with reference to FIG. FIG. 4 is a block diagram showing a schematic configuration of a control system in an embodiment of the image forming apparatus to which the present invention is applied.

The present control system is composed of a control device 56, an input unit including a sensor and the like, and an output unit such as a motor and a clutch. The control device 56 outputs a drive signal to the output unit in response to an input signal from the input unit. Is designed to be output.

The control device 56 is composed of a CPU and the like, processes image data to be image-formed, and outputs it to the light emitting section 14 in consideration of the scanning timing. Further, the controller 56 controls the transfer sheet sensor 22, the first double feed sensor 23, the second double feed sensor 24, the registration sensor 25,
The main motor 57, the paper feed clutch 58, the transport system clutch 59, and the like are controlled according to detection signals from the timing sensor 26 and the discharge sensor 27. further,
The control device 56 outputs a signal to that effect to the notifying unit 60 disposed at an appropriate position on the upper surface of the image forming apparatus in order to notify the double feeding of the transfer paper when the double feeding of the transfer paper is detected. ing.

The main motor 57 drives the paper feed rollers 3, 4 to the discharge roller pairs 18, 19 via a paper feed clutch 58 and a transport system clutch 59. When the paper feed clutch 58 is turned on, the drive force of the main motor 57 is applied to the paper feed rollers 3 and 4, the first and second separation roller pairs 7,
It is transmitted to a transfer paper feeding mechanism such as 10. When the conveyance system clutch 59 is turned on, the driving force of the main motor 57 is applied to the registration roller pair 11 and the discharge roller pairs 18 and 19.
And the like to the transfer paper transport mechanism. And
In the case of continuous image formation such as continuous copying, the transfer papers in the paper feed cassettes 1 and 2 are fed out at a constant interval, sequentially conveyed, and guided to the transfer unit 16.

Next, the operation of this embodiment will be described with reference to FIGS. 1A and 1B are cross-sectional views showing a transfer sheet conveyance state. FIG. 1A shows a state in which the first double feed sensor 23 is on, and FIG. 1B shows a state in which the first double feed sensor 23 is off. FIG. 5 is a timing chart showing the operation of the present embodiment, and shows the case where, for example, the transfer papers fed from the paper feed cassette 1 are double fed.

When the operation is started at time t ₁ , by turning on the main motor 57, the paper feed roller 3 starts to rotate to start feeding the transfer paper, and the forward rotation roller 5 and the reversal roller 5 are started. 6 starts rotating. The forward rotation roller 5 and the reversal roller 6 carry out the transfer paper carried in from the paper feed cassette 1 and carry it out to the registration roller pair 11.
At this time, the transfer paper passes through the first double feed sensor 23 and the registration sensor 25, and sequentially turns on these sensors 23 and 25. The registration roller pair 11 is a registration sensor 25.
Is turned on, and after a lapse of a predetermined time T ₀ , it is determined that the transfer sheet is nipped, and driving is started to guide the transfer sheet to the photoconductor 12.
Then, the forward rotation roller 5 waits for the registration roller pair 11 to start driving until the next transfer sheet is carried in (t
_(4th point), it will be paused.

On the other hand, as shown in FIG. 1, when the transfer paper is double-fed, the double-feed transfer paper is separated and the forward rotation roller 5
And the reversing roller 6 remain between the first double feed sensor 2
3 continues to turn on. At this time, the forward rotation roller 5 is stopped and the reversal roller 6 is driven, so that the double-fed transfer sheet is fed backward (FIG. 1A). By this reverse feeding, the first double feeding sensor 23 changes from on to off (t
₍ Time ₂ ), and further, after a lapse of time when the nip between the normal rotation roller 5 and the reversal roller 6 of the paper is released, the reversal roller 6 is stopped (time t ₃ ; FIG. 1B). Then, when the next transfer sheet is carried in, the driving is started in synchronization with the sheet feeding roller 3. Note that at time t ₂ , that is, the first double feed sensor 23
The reversing roller 6 may be stopped immediately after turning off.

If no double feed occurs, the first
The reverse roller 6 is stopped when the double feed sensor 23 changes from on to off.

As described above, since the rotation drive of the reversing roller 6 is controlled by the change of the first double feeding sensor 23 from ON to OFF, the double feeding transfer sheet is folded by the continuous driving of the reversing roller 6. Can be prevented. Further, as a result, the driving torque of the reversing roller 6 can be increased, so that the separating ability of the first separating roller pair 7,
That is, the performance of preventing double feeding can be improved.

In this embodiment, the first double feed sensor 23
The reverse roller 6 is controlled to be stopped from ON to OFF. However, after the drive of the forward rotation roller 5 is stopped, the state of the first double feed sensor 23 is checked, and if ON, the reverse roller 6 is continuously driven. Alternatively, the first multi-feed sensor 23 may be stopped after being turned off.

In this embodiment, the first separating roller pair 7 is used.
As described above, the reversing roller 9 of the second separating roller pair 10
Can also be applied to control by turning on / off the second double feed sensor 24.

[0025]

As described above, according to the present invention, the driving of the reversing roller is stopped at the time when the paper detecting means detects the change from the presence of the paper to the absence of the paper. It can be surely prevented. As a result, it is possible to prevent the occurrence of a jam and ensure an appropriate copying operation when applied to an image forming apparatus or the like.

[Brief description of drawings]

1A and 1B are cross-sectional views showing a transfer sheet conveyance state, in which FIG. 1A shows a state in which a first double feed sensor 23 is on, and FIG. 1B shows a state in which the first double feed sensor 23 is off.

FIG. 2 is a sectional view showing a schematic configuration of an image forming apparatus to which the present invention is applied.

FIG. 3 is a perspective view showing a structure of a paper feed cassette 2.

FIG. 4 is a block diagram showing a schematic configuration of a control system in an embodiment of an image forming apparatus to which the present invention is applied.

FIG. 5 is a timing chart showing the operation of the present embodiment,
The case where the transfer papers fed from the paper feed cassette 1 are double-fed is shown.

FIG. 6 is a sectional view showing a schematic configuration of a conventional image forming apparatus.

FIG. 7 is a cross-sectional view showing conveyance of double-fed transfer paper.

[Explanation of symbols]

 1, 2 paper feeding cassette 3, 4 paper feeding roller 5, 8 forward rotation roller 6, 9 reversing roller 7 first separation roller pair 10 second separation roller pair 11 registration roller pair 13 charging device 14 light emitting unit 15 polygon mirror 22, 22 'Transfer paper sensor 23 First double feed sensor 24 Second double feed sensor 25 Registration sensor 26 Timing sensor 27 Ejection sensor 56 Control device 57 Main motor 58 Paper feed clutch 59 Conveyance system clutch 60 Notification section

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Masahiro Shinohara 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Industrial Co., Ltd. (72) Kenji Oda 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Within Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A forward rotation roller, which is disposed in a sheet conveyance path that conveys at regular intervals and is driven at regular intervals to separate and carry out a sheet to be carried in, and in synchronization with the forward rotation roller. Conveyance that includes a separation roller pair including a reversing roller that is driven, and a sheet detection unit that is disposed close to the separation roller pair on the downstream side in the sheet conveyance direction and that detects the presence or absence of a sheet at the separation roller pair position 1. A sheet separating apparatus, comprising a drive control section for stopping driving of the reversing roller when the sheet detecting section detects a change from the presence of a sheet to the absence of a sheet.