JPS62222949A - Paper jam preventer - Google Patents

Abstract

PURPOSE:To prevent any delay of image forming work due to a paper jam happening and damage to a device both from occurring, by stopping progress of the image forming work afterward at a time when folding or bending is produced at a front end of paper being on standby as coming into contact with a timing roller. CONSTITUTION:A timing roller 2 is constituted of a pair of rollers consisting of a drive roller 2a and a driven roller 2b. A feed guide 4 is formed between a paper feeding part installing a paper cassette 26 and provided with a paper feed roller 28 and the timing roller 2. In the lower side of this guide 4, there is provided with a paper detecting switch 5 exposes an actuator 5a in a conveying passage, rocking in an arrow D direction by contact with a lower surface of the paper fed out of the paper feeding part, and detects a fact that the paper has been fed. At the time of feeding the paper 11, both these rollers 2a and 2b are stopped. Therefore, the paper 11 are stopped and on standby as its front end comes into contact with a taction part between these rollers 2a and 2b. A detection sensor 1 detects a front end of the paper being on standby.

Description

Detailed Description of the Invention Technical Field The present invention relates to a paper jam prevention device for preventing paper jams (hereinafter referred to as jams) from occurring during conveyance of fed paper in an image forming apparatus. .

<Summary of the Invention> In summary, the paper jam prevention device according to the present invention includes a detection means for detecting the leading edge of paper waiting to be introduced into the transfer section, and the detection means does not detect the waiting paper. In this case, the progress of the image forming operation is stopped to prevent the occurrence of a jam.

<Prior Art and Its Disadvantages> In an image forming apparatus using electrophotography, such as a copying machine, a developer image is formed on a photoreceptor, and this is transferred onto paper in a transfer process. Therefore, in order to form an image at a proper position on the paper, the paper must be introduced into the transfer section in synchronization with the operation of the photoreceptor.

For this reason, in the conventional image forming apparatus, a timing 1 cola is provided between the paper feeding section and the transfer section. This timing roller is composed of a pair of rollers, and is selectively given a driving force. When paper is fed from the paper feed section prior to the operation of the photoreceptor, the timing roller is not driven, and the paper comes into contact with the timing roller and stops, waiting to be introduced into the transfer section. Thereafter, the movement of the photoreceptor progresses, and at a point in time in synchronization with the movement, the timing roller is driven and the paper is guided to the transfer section. In this way, the timing roller has to stop the fed paper by making contact with it, so the front edge of the paper bends at the position of the timing roller, causing a jam at the transfer section where the corners are extremely small while the paper passes through. There were times when I had to stop.

However, none of the conventional image forming apparatuses is designed to detect that the leading edge of the sheet is bent near the timing roller. For this reason, it is not possible to prevent jams from occurring in the transfer section, which not only impedes the progress of image forming work but also causes damage to devices such as photoreceptors. In view of the above-mentioned drawbacks of the conventional method, when the leading edge of the paper that is waiting in contact with the timing roller bends, the progress of the subsequent image forming operation is stopped, and the image forming process due to the occurrence of jam 1 is stopped. An object of the present invention is to provide a paper jam prevention device that can prevent work delays and damage to the device.

<Structure and Effects of the Invention> The paper jam prevention device of the present invention detects the front edge of the paper that is waiting in contact with a timing roller after the paper is fed from the paper feed unit and before being introduced into the transfer unit. and an operation stopping means that prohibits the paper from being introduced into the transfer unit when the paper is on standby [1] and the paper is not detected by the paper detection means.
It is characterized by +iif.

With the above configuration, according to the present invention, when the front end of a sheet of paper that is on standby is bent, the detection means provided near the timing roller does not detect the sheet of paper. While the paper is on standby, the entire front end of the paper should come into contact with the timing roller, but if the front end is bent, a portion of the paper does not come into contact with the timing roller and the detection means detects the paper. This is because it is not possible. In this way, if the detection means does not detect the paper even though the paper is on standby, it is determined that the paper is bent, and the operation stop means prohibits the introduction of the paper into the transfer section. , the progress of subsequent image forming operations can be stopped. This prevents the paper from becoming stagnant after the transfer area.
There is no occurrence of CJ, and it is possible to prevent delays in work and damage to equipment.

<Embodiment> FIG. 2 is a schematic front sectional view showing the configuration of a copying machine equipped with a paper jam prevention device according to an embodiment of the present invention.

Approximately in the center of the copying machine main body 21 is a photosensitive drum J.
22 is provided, and together with each device on the outer periphery, constitutes a copying process section. On the right side of this copy process section,
Attach the paper cassettes 25.26 and press the paper feed rollers 27.2.
A paper feeding section including a paper feed section 8 is configured. On the other hand, on the right side of the copying process section, there is a general conveyance belt 29 and a fixing device "F?".
30 is provided, and a paper ejection unit is constituted by a paper ejection 1-ray 31 and a paper ejection 11-ray 32.

A paper transport path is formed from the paper feed section to the paper discharge section via the copy process section. In this paper transport path, a timing roller 2 and a paper entry detection switch 5 are provided between the paper feeding section and the copying process section. ,
Further, a transfer charger 23 is attached to the photosensitive drum 22 with a gap L-1 at a position where the paper conveyance path passes through the copying process section, and constitutes a transfer section 24 .

A document table 33 is formed on the top surface of the zero bed of the copying machine.

The image of the document placed on the document table 33 is scanned by a light source 34 included in the scanner.

The light reflected from the original by the light source 34 is irradiated onto the surface of the photoreceptor drum 22 via the lens 35 as shown by the dashed line in the figure, and is exposed to form an electrostatic latent image. The photosensitive drum 22 rotates in the direction indicated by the arrow, and the electrostatic latent image formed on the surface is visualized by being supplied with developer from the developing device 36 . The developer image formed in this way is transferred onto the paper in the transfer section 24. The paper onto which the image has been transferred is led to a fixing device 30 by a conveyor belt 29, and after being heated and pressurized to fix the image, it is discharged to a paper discharge section.

In the above copying process, the paper is
The paper is fed from the paper feed section prior to rotation in the six directions of arrows. At this time, the timing roller 2 is not rotating, and the front end of the sheet comes into contact with the timing roller 2 and stops.

The photosensitive drum 22 rotates in the six directions of the arrow, and the timing roller 2 starts rotating at the timing when the front end of the image reaches the transfer section 24 and the front end of the paper is guided to the transfer section 24. A paper entry detection switch 5 provided on the paper feeding section side of the timing roller 2 in the conveyance path is a switch that detects when paper is fed from the paper feeding section and reaches the position of the timing roller 2 .

FIG. 1 is a front view showing the configuration of essential parts of the copying machine.

The timing roller 2 includes a driving roller 2a and a driven roller 2b.
It consists of a pair of rollers. Drive roller 2
A driving force is transmitted by a transmission device (not shown), and it rotates in the direction of arrow 13). The driven roller 2b is the driving roller 2
a is in contact with the drive roller 2a under a constant pressing force, and the drive roller 2a
Rotation in the direction of arrow B causes rotation in the direction of arrow C. A conveying guide 4 is formed between the timing roller 2 and a paper feeding unit equipped with a paper cassette 26 and a paper feeding roller 28 . A paper entry detection switch 5 is provided below the conveyance guide 1'4. The paper entry detection switch 5 has an actuator 5a exposed in the conveyance path. This actuator5. J swings in the direction of the arrow due to contact with the bottom surface of the paper fed from the paper feeding section, and detects that the paper has been fed.

When feeding the paper 11, the drive roller 2a is not receiving any driving force and is stopped together with the driven roller 2b. Therefore, the front end of the paper 11 comes into contact with the contact portion between the drive roller 2a and the driven roller 2b, and the paper 11 stops and waits to be introduced into the transfer section.

A detection sensor 1 consisting of a light emitting element 1a and a light receiving element 1b is provided above the conveyance guide 4 in the vicinity of the timing roller 2. This detection sensor 1 is a detection means of the present invention, and detects the leading edge of a sheet of paper that is on standby.

FIG. 3 is a block diagram of the control section of the copying machine.

The CPU 41 receives the count data of the on-signal of the four ink printer 48 from the counter 45 via the I10 ink face 44. The four interrupter 48 detects a slit in a PT disk 49 provided coaxially with the photoreceptor 1.22, and outputs an ON signal to the counter 45. The Cr'U 41 knows the progress status of the copying process from this count data. When this count data reaches a predetermined value, I? Control data is output based on the control program for each device stored in OM 4.2. This control data includes control data for the solenoid S L I that is output to the solenoid drive section 46 . This solenoid S
], 1 turns on/off transmission of the driving force to the driving roller 2a. Furthermore, detection data from the detection sensor and the paper entry detection switch 5 is input to the CPtJ 41 via the I10 ink face 44.

After the paper entry detection switch 5 detects the paper entry, if the detection sensor I21 does not detect the paper, no control data is output to the solenoid drive unit 4G.

FIG. 4 is a flowchart 1 showing a part of the operation of the copying machine.

When the power is turned on to the copying machine main body 21, step nl (
The warming amplifier is started at step n2 (hereinafter referred to simply as "ni"). When the warming-up is completed at n2, the process proceeds to n3, where copy data is input by the operator's key operation. After this, at step n4
When the print switch is operated in
□ Feed paper from either 25 or 26. The paper feed roller is driven m'tc until the paper entry detection switch 5 is turned on at n6, and when the paper entry detection switch 5 is turned on at n6, the process proceeds to 07. At n7, it is determined whether the detection sensor 1 is in the on state.

When the detection sensor 1 is turned on at n7,
It is determined that the leading edge of the paper in the standby state is not bent, and the process proceeds to n8 to perform a copying operation.

If detection sensor 1 is not turned on at n7,
It is determined that a bend has occurred in the front edge of the paper in the standby state, and n9. Proceed to nlo. In n9, copy machine body 21
A display prompting the paper paste sensor 1- is displayed on the operation section (not shown) on the top surface of the machine. This display operation is performed when the fed paper is taken out from between the paper feeding section and the timing roller 2, and the n I O
Im&iL is performed until the paper entry detection switch 5 is turned off. When the paper entry detection switch 5 is turned off at n10, the process returns to n3 and the operation is repeated again from data input. In "2" below, n7. n9. n and 10 correspond to the operation stopping means of the present invention.

As described above, according to this embodiment, the detection sensor 1 detects the leading edge of the paper that is in the standby state after being fed from the paper feeder, and if the detection sensor 1 is not outputting an on signal, then the paper When the front edge of the paper is bent and the sensor 1 cannot detect the front edge of the paper, the progress of the copying operation is stopped and the operator is prompted to insert the paper. In this way, it is possible to prevent bent sheets from being introduced into the transfer section and prevent jams from occurring.

Note that the front edge of the paper is likely to bend at the corner due to contact with the timing roller, so by installing detection sensors near both edges of the paper in the direction perpendicular to the paper feeding direction, the front edge It is possible to reliably detect the occurrence of a bend in the curve. Furthermore, if there are multiple sizes of paper that can be fed, if the detection sensor is configured to move in the direction perpendicular to the paper feeding direction, the detection sensor that should be installed regardless of the number of paper sizes that can be fed. The number of can be two. Further, in the case of a device having a paper feed tray, a detection sensor is connected to a paper feed guide operated by an operator according to the size of the paper to be fed, and a driving means is not required to move the detection sensor. In addition, although a reflective photosensor is used as the detection sensor in this embodiment, other photosensors such as a transmission type can also be used.

[Brief explanation of drawings]

FIG. 1 is a front view showing the configuration of main parts of a copying machine in which a paper jam prevention device according to an embodiment of the present invention is used; FIG. 2 is a schematic front cross-sectional view showing the configuration of the copying machine; The figure is a program diagram of the control section of the copying machine, and FIG. 4 is a flowchart showing part of the operation of the copying machine. I-detection sensor (detection means), 2-timing roller.

Claims (1)

[Claims] (1) A detection means that detects the leading edge of the waiting paper by contacting the timing roller after the paper is fed from the paper feeding section and before being introduced into the transfer section; A paper jam prevention device comprising: operation stopping means for prohibiting introduction of paper into a transfer section when paper is not detected.