JP2001215847A - Electrophotographic image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit write of an image to the portion of a photoreceptor protruded from a sheet of paper when detected that the paper size is smaller than the image size. SOLUTION: The electrophotographic image forming device detects the paper size with the paper sensor of a picking portion located immediately after a hopper. When detected that the paper size is smaller than an image size, the write of the image to the portion of the photoreceptor which protrudes the sheet of paper is prohibited. Or a paper size error is notified to the upper priority unit, and the printing data transmission to the upper priority unit is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, and more particularly to a method for writing an image onto a photosensitive member without protruding from a sheet when the sheet size is detected to be smaller than the image size. The present invention relates to an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, an example of this type of electrophotographic image forming apparatus will be described with reference to FIGS.

In a conventional electrophotographic image forming apparatus,
The paper size error is detected not by the pick sensor 21 but by the registration sensor 19. Therefore, the timing at which a paper size error can be detected is delayed, and in the case of continuous printing, images subsequent to the paper at which the paper size error is detected have already been drawn and developed on the photosensitive belt 1 (FIG. 5). of). Therefore, conventionally, the image drawn on the photoreceptor belt 1 must be picked up and printed before the paper size error is detected. In addition, writing of an image to the photosensitive belt 1 was not stopped when a paper size error was detected. In this case, if the image size is larger than the paper size, the image protrudes from the paper, and the protruding portion of the image is transferred to the fixing roller, causing the back of the paper to be stained. Therefore, the separation between the paper and the transfer roller did not work well, and there was a possibility that the paper jam occurred.

In particular, in the case of an apparatus for simultaneously transferring and fixing an image to a sheet as shown in FIG. 1, the danger is increased. Further, even if a cleaning device that collects an image developed on the photoreceptor belt 1 that does not need to be transferred without transferring it to the paper is provided on the photoreceptor belt 1 or the transfer roller 2, toner is wasted or a cleaning sequence is required. It takes extra time.

[0005]

The problem with this conventional electrophotographic image forming apparatus is that when the sheet is smaller than the image size, the image is printed up to the trailing edge of the sheet. When the image is transferred, the paper is entangled in the transfer roller to cause a jam, and the image protruding from the paper is transferred to the fixing roller to be stained on the back of the paper.

An object of the present invention is to provide an electrophotographic image forming apparatus characterized in that, when it is detected that the sheet size is smaller than the image size, the portion of the image written on the photoreceptor is not protruded from the sheet. It is to provide a device.

[0007]

In the electrophotographic image forming apparatus of the present invention, the paper size is detected by a paper sensor at a pick portion located immediately after the hopper, and when the paper size is detected to be smaller than the image size. In addition, the writing of the image on the photoreceptor is not performed at a portion protruding from the paper.

Further, the electrophotographic image forming apparatus of the present invention comprises:
The paper size is detected by a paper sensor of a pick portion located immediately after the hopper, and when it is detected that the paper size is smaller than the image size, a paper size error is notified to a higher-level device, and print data transmission of the higher-level device is performed. It is characterized by being stopped.

Further, in the electrophotographic image forming apparatus of the present invention, the photosensitive member is a photosensitive belt or a photosensitive drum.

Further, the electrophotographic image forming apparatus of the present invention is characterized in that the image writing on the photosensitive member is performed by a laser beam or a light emitting diode.

[0011]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows an embodiment of the present invention.
Referring to FIG. 1, the electrophotographic image forming apparatus 30 of this embodiment includes a photosensitive belt 1 on which an image is written, a charger 12 for uniformly charging the surface of the photosensitive belt 1, and a surface of the photosensitive belt 1. A laser unit (may be an LED) for writing an image of each color by exposing the image (yellow laser unit 3, magenta laser unit 4, cyan laser unit 5, black laser unit 6) and developing the written image of each color Developing devices (a yellow developing device 7, a magenta developing device 8, a developing device for forming a toner image on the surface of the body belt 1)
A cyan developing device 9, a black developing device 10), a transfer roller 2 and a fixing roller 13 for transferring and fixing a developed image to a sheet, an eraser 11 for removing electric charges remaining on the surface of the photoreceptor belt 1, and a sheet storing section. Hopper 29,
A pick roller 22 for picking a sheet from a hopper 29;
A hopper motor 25 for rotating the pick roller 22 and a transport roller 1 for transporting a sheet to a place where an image is transferred
5, 16, 17, 18; a registration roller 14 for temporarily stopping the conveyed sheet to finely adjust the alignment between the sheet and the image; a registration sensor 19;
And a pick sensor 21, a belt motor 28 for rotating the photoreceptor belt 1, a registration motor 23 for rotating the registration roller 14, a feed motor 24 for rotating the conveyance rollers 15 to 18, a sheet conveyance, the photoreceptor belt 1, The control unit 27 controls the developing units (7 to 10) and the like, and has a function of forcibly masking and not outputting image data sent from the information processing device 26, which is an upper-level device, to the laser units 3 to 6. It is configured.

Next, the overall operation of this embodiment will be described in detail with reference to FIGS.

First, a print request is sent to the control unit 27 from the information processing device 26 as a host device. At this time, the paper size of the data to be printed is sent from the information processing device 26 to the control unit 27 at the same time, or the control unit 27 recognizes the paper size by the paper size sensor of the hopper 29 (S41 in FIG. 2). . The control unit 27 activates the laser of each color, rotates the photoreceptor belt 1, and turns on the charger 12 and the eraser 11. When the activation of the laser units 3 to 6 is completed and the printer is ready for printing, the information processing device 26 transmits image data of each color to the electrophotographic image forming device 30.
The control unit 27 of the electrophotographic image forming apparatus 30 starts writing the electrostatic latent image on the photosensitive belt 1 by the laser units 3 to 6 (see FIG. 4). The electrostatic latent images written by the laser units 3 to 6 are developed by the respective developing units 7 to 10 and transferred to the transfer roller 2.

On the other hand, when the image written on the photoreceptor belt 1 reaches the transfer roller 2, the sheet is picked by the pick roller 22 at a proper timing so that the sheet comes to the transfer roller 2, and the hopper 29. Then, the transfer is started (FIG. 4). At this time, the paper is
Is turned on, and the paper size length is determined from the time and the paper transport speed (S42 in FIG. 2). Alternatively, the regular pick sensor ON time for each paper size is prepared as a table, and the pick sensor 2
The time when 1 is on may be compared. Then, when it is determined that the value obtained by subtracting the margins at the front and rear of the sheet from the sheet size length is shorter than the size of the print data, the laser units 3 to 6 write the photoreceptor belt 1. Stop image output (S43 in FIG. 2, FIG. 4)
of).

As described above, according to this embodiment, it is detected that the printing paper is smaller than the image size during printing in the electrophotographic image forming apparatus such as a printer, a facsimile, and a copying machine, and that the image runs off the paper. sometimes,
The writing of the image on the photoreceptor belt 1 is stopped, and the image transferred to the rear end of the sheet causes the sheet to be entangled in the transfer roller 2 to cause a jam. It is possible to prevent the back of the paper printed on the paper from becoming dirty.

Next, referring to FIG. 1 in conjunction with FIG. 3 showing a flow chart of the operation of another embodiment of the present invention, the difference from the embodiment of FIG. Control unit 2 prints a mask of the print data when detecting
In step 7, the print data is sent to the information processing apparatus 26 notifying the information processing apparatus 26 that is sending the print data of a paper size error, instead of preventing printing of the portion that protrudes from the paper. The point is to stop.

[0018]

As described above, the effect of the present invention is as follows.
If the paper is smaller than the image size, the image will be printed up to the trailing edge of the paper.Therefore, when the image at the trailing edge of the paper is transferred, the paper will get caught in the transfer roller and jam, Another object of the present invention is to prevent the paper from being transferred to the fixing roller and being stained on the back of the paper.

The reason is that a paper size error can be detected before the laser unit writes the electrostatic latent image on the photosensitive belt and is developed by the developing device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of an operation according to the embodiment;

FIG. 3 is a flowchart showing an example of an operation according to another embodiment.

FIG. 4 is a time chart showing an example of an operation according to the embodiment.

FIG. 5 is a time chart showing an example of an operation in a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor belt 2 transfer roller 3 yellow laser unit 4 magenta laser unit 5 cyan laser unit 6 black laser unit 7 yellow developing device 8 magenta developing device 9 cyan developing device 10 black developing device 11 eraser 12 charger 13 fixing roller 14 resist roller 15, 16, 17, 18 Conveying roller 19 Registration sensor 20 Paper sensor 21 Pick sensor 22 Pick roller 23 Registration motor 24 Feed motor 25 Hopper motor 26 Information processing device 27 Control unit 28 Belt motor 29 Hopper 30 Electrophotographic image forming device

Claims (6)

[Claims] A paper size is detected by a paper sensor of a pick portion located immediately after a hopper, and when it is detected that the paper size is smaller than an image size, a portion of an image to be written on a photoconductor protruding from the paper is removed. An electrophotographic image forming apparatus, wherein the processing is not performed. 2. A paper sensor of a pick portion located immediately after the hopper detects a paper size, and when it is detected that the paper size is smaller than an image size, a paper size error is notified to a higher-level device. An electrophotographic image forming apparatus, wherein the transmission of print data is stopped. 3. An electrophotographic image forming apparatus according to claim 1, wherein said photoconductor is a photoconductor belt. 4. An electrophotographic image forming apparatus according to claim 1, wherein said photosensitive member is a photosensitive drum. 5. The electrophotographic image forming apparatus according to claim 1, wherein the image writing on the photoconductor is performed by a laser beam. 6. The electrophotographic image forming apparatus according to claim 1, wherein the image writing on the photoconductor is performed by a light emitting diode.