JPH07117894A - Image forming device - Google Patents

Abstract

PURPOSE:To conduct appropriate cleaning to the type of conveyance failure for a transfer member by making cleaning control different between pickup conveyance failure and jamming in the midst of conveyance. CONSTITUTION:In case of jamming, a printer controller 22 determines it to be jamming due to pick-up miss if a paper feed sensor 10 fails to turn on within a specific period even though a paper feed action starts with the start of the rotation of a paper feed roller 9. For this type of jamming, a cleaning command is issued to an engine control part 24, a high pressure control part 29 is activated, an electric potential of the polarity opposite to that at the time of transfer is applied to a transfer roller 7, toner adhering to a transfer roller 7 is shifted to a photosensitive element drum 1. The shifted toner is removed by a cleaning blade 8. If a different type of jamming occurs, a controller 22 alerts an operator to remove a recording paper sheet which has not been conveyed properly and conducts cleaning work for the transfer roller 7 in a similar manner.

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 for forming an image by, for example, transferring a toner image formed on a photoconductor onto a recording medium.

[0002]

2. Description of the Related Art In recent years, a laser printer has been widely used as an image forming apparatus for printing character information and image information. In this laser printer, an image is formed as an electrostatic latent image on a charged photosensitive member, and this latent image is developed with toner to form a visualized toner image, which is transferred onto a recording paper and subjected to a heat fixing process. It is an image completed through the steps. There are various methods for transferring the toner image onto the recording paper, one of which is by a transfer roller.

The transfer by the transfer roller is applied to the toner image when the transfer roller is arranged in pressure contact with the photoconductor and the recording paper is passed between the photoconductor on which the toner image is formed and the transfer roller. This is performed by applying a transfer bias potential having a polarity opposite to the electric charge to the transfer roller and adsorbing and transferring the toner image on the photoconductor onto the recording paper.

Further, the recording paper is carried on the carrying path by a carrying means having a paper feeding roller, various carrying rollers, a paper discharging roller and the like. That is, the recording paper sent by the rotation of the paper feed roller is carried toward the photoconductor and the transfer roller by the carrying roller, and the recording paper on which the toner image is transferred is carried toward the fixing roller by the carrying roller,
The recording paper on which the toner image is fixed is ejected by the paper ejection roller.

[0005]

In such a laser printer, when the recording sheet is conveyed by the conveying means, there may be a conveyance failure such as a recording sheet pickup error or a paper jam, that is, a jam. Depending on the timing of occurrence of such a jam, the toner of the toner image already formed on the photoconductor may be directly transferred to the transfer roller. The transfer of the toner onto the transfer roller results in the contamination of the recording paper to be fed next, or the transfer bias potential applied to the transfer roller being substantially lowered, resulting in a transfer failure.

By the way, the degree of contamination of the transfer roller when a jam occurs greatly differs depending on where the recording paper is jammed. That is, when a jam occurs, the transfer roller is heavily soiled when the toner image is already formed on the photoconductor, but when the toner image is not yet formed on the photoconductor, the toner is not formed on the photoconductor. Is hardly adhered to the transfer roller, so that the transfer roller is hardly soiled. If the jam that occurred is a pick-up error due to the paper feed roller, etc.,
Since the toner image is not formed on the photoconductor, the transfer roller is not contaminated.

Therefore, the present invention was made by paying attention to the fact that the transfer member has a different degree of contamination depending on whether the recording medium is poorly conveyed due to a pickup error or a jam during conveyance. In the case where the recording medium is poorly conveyed due to the above, image formation capable of performing an appropriate cleaning process on the transfer member according to the type of the poor conveyance is performed in order to prevent the next conveyed recording medium from being soiled or having a poor transfer. The purpose is to provide a device.

[0008]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a conveying means for picking up and conveying recording media one by one, a photoconductor on which a toner image is formed, and a recording medium to be conveyed. A transfer member for pressing the toner image onto the recording medium by pressing the photosensitive member through the cleaning member, a cleaning unit for cleaning the transfer member, and a conveyance defect detection for detecting a conveyance defect of the recording medium by the conveyance unit. In the image forming apparatus, the image forming apparatus comprises: means for controlling the cleaning means when a conveyance failure of the recording medium is detected by the conveyance failure detection means. The image forming apparatus is characterized in that the control for the cleaning unit is made different depending on whether the jam is during conveyance or not.

[0009]

When the conveyance failure of the recording medium by the conveyance means occurs, the control means controls the cleaning means in response to the pickup failure if the conveyance failure is a pick-up error, while the conveyance failure results in the middle of conveyance. In the case of a jam, the cleaning unit is controlled accordingly, and the cleaning unit cleans the toner on the transfer member onto which the toner on the photoconductor has been transferred. In this way, the transfer member is appropriately cleaned according to the type of conveyance failure.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing the configuration of a laser printer to which the present invention is applied.

The surface of the photosensitive drum 1 as a photosensitive member is
The charging brush 5 is charged to a predetermined charge. The laser light modulated by the image signal emitted from the semiconductor laser oscillator 2 is scanned in the main scanning direction by the polygon mirror 3 rotating by the polygon mirror drive motor 3a, reflected by the reflection mirror 4 and incident on the photosensitive drum 1. To do. Photoconductor drum 1
Is rotated in the direction a in the figure to perform sub-scanning, and an electrostatic latent image is formed on the surface of the photosensitive drum 1 by the above operation. This electrostatic latent image is developed by the developing device 6 and converted into a toner image.

The paper feed roller 9 causes the recording paper C to be fed by a paper feed command.
The feeding of P is started. The paper feed state of the recording paper CP is detected by the paper feed sensor 10, and the recording paper CP is conveyed on the conveyance path and temporarily stopped by a timing roller (not shown). Then, the recording paper CP is synchronized with the timing when the toner image on the photosensitive drum 1 reaches the transfer position. It is transported to the transfer position. At this time, since a bias having a polarity opposite to the charge of the toner on the photoconductor drum 1 is applied to the transfer roller 7 as a transfer member, the toner image on the photoconductor drum 1 is transferred to the recording paper CP. Chart paper CP
The toner image transferred to is fixed by the fixing roller 11 and then discharged by the discharge roller 13. This recording paper CP
The discharge of the sheet is detected by the sheet discharge sensor 12. The toner remaining on the photosensitive drum 1 after the image transfer is removed by the cleaning blade 8.

FIG. 2 is a block diagram showing the configuration of the control system of the laser printer. The host computer 21 outputs a print request signal for requesting printing of an image read from an image reading device (not shown) or the like, and converts the read image or the like into an image signal and outputs the image signal. The printer controller 22 receives a print request signal from the host computer 21 and outputs a command for printing to the engine control unit 24. The operation panel 23 gives the number of prints and other printer control information to the printer controller 22. The engine control unit 24 controls each unit of the printer based on a command from the printer controller 22. The conveyance control unit 25 controls the feeding of the recording paper CP, and the scanner control unit 28 controls the polygon mirror 3
It controls the operation by. The high voltage controller 29
Charging the photosensitive drum 1, developing bias, transfer roller 7
High voltage control such as application of a transfer bias potential to the laser is performed, and the laser control unit 30 performs modulation control of laser light. The paper feed sensor 10 is used as a sensor for recognizing the size of the conveyed recording paper CP. If the recording paper CP to be fed by the rotation of the paper feed roller 9 does not turn on the paper feed sensor 10 within a predetermined time, it is judged that a jam of the pickup mistake of the recording paper CP has occurred. If the recording paper CP to be ejected does not turn on the paper ejection sensor 12 within a predetermined time after the start of feeding, it is determined that a paper jam jam has occurred in the middle of the conveyance path.

In the structure shown in FIGS. 1 and 2, the paper feed roller 9 and the paper discharge roller 13 function as conveying means,
Paper feed sensor 10, paper discharge sensor 12, and engine control unit 2
Reference numeral 4 functions as a conveyance failure detection unit that detects a conveyance failure of the recording paper CP, and the printer controller 22 and the engine control unit 24 each function as a control unit.

Upon receiving the print request signal from the host computer 21, the printer controller 22 outputs a command for printing to the engine control unit 24. In response to this command, the engine control unit 24 outputs a paper feed command signal to the transport control unit 25 to command the start of paper feeding, and at the same time commands the scanner control unit 28 to perform scanning preparation, and also to expose the light via the high voltage control unit 29. The body drum 1 is charged and the developing bias is set to prepare for printing. In addition, a vertical synchronization request signal is output to the printer controller 22, waiting for reception of the vertical synchronization signal, and when the vertical synchronization signal is output, it is input from the host computer 21 to the laser control unit 30 via the printer controller 22. The laser light is modulated based on the image signal, whereby an electrostatic latent image is formed on the photosensitive drum 1.

In the illustrated laser printer, the toner image on the photosensitive drum 1 is transferred onto the recording paper CP by the transfer roller 7, and in this type of image forming apparatus, the toner on the photosensitive drum 1 is Since it directly adheres to the transfer roller 7 and causes the recording paper CP supplied later to be soiled, it has a cleaning means for cleaning the transfer roller 7. To clean the transfer roller 7 by this cleaning means, for example, a potential having a polarity opposite to that at the time of transfer is applied to the transfer roller 7 to transfer the toner adhered on the transfer roller 7 to the photosensitive drum 1, and at least this processing is transferred. The process is completed by performing the roller 7 once or more. The cleaning means is not limited to the one described above, but can be changed as appropriate.

Before explaining the detailed operation of the image forming apparatus of the present invention, the general operation of the apparatus will be described.
From the host computer 21, image data read by an image scanner (not shown), data regarding the size of the image, and the like are sent to the printer controller 22. The host computer 21
Alternatively, when a print request signal is output from the operation panel 23, the conveyance control unit 25 operates and the recording paper CP is sent out from the designated paper feed port. The recording paper CP sent out is conveyed toward the photoconductor drum 1 and the transfer roller 7 by a conveying roller (not shown), and the recording paper CP onto which the toner image is transferred is fixed by the fixing roller 11 by a conveying roller (not shown).
The recording paper having the toner image fixed thereon is ejected by the paper ejection roller 13. When the recording paper CP is poorly conveyed, the paper feed sensor 10 or the paper discharge sensor 12
Thus, the occurrence of jam is detected. When a jam occurs, the toner of the toner image already formed on the photoconductor drum 1 directly adheres to the transfer roller 7 and causes the recording paper CP supplied later to be soiled. Therefore, when the cause of the jam is removed and the sheet is returned to the transportable state, the printer controller 22 outputs a command to the engine control unit 24 for cleaning the transfer roller 7. Cleaning of the transfer roller 7 is performed by the above-mentioned cleaning means.

In particular, in the present embodiment, the above-mentioned control of the cleaning means is made different depending on whether the conveyance failure is a pickup error by the paper feed roller 9 or a jam during conveyance.

The above is the general operation of the laser printer. The processing operation when a jam occurs will be described with reference to the flowchart of FIG. This flow chart is
It relates to the printer controller 22.

When a jam occurs, the printer controller 22 determines whether the jam is a pick-up mistake of the recording paper CP or another jam (S1).
3). The printer controller 22 is the engine control unit 2.
4, it is determined whether or not there is a pickup error jam based on the output state of the paper feed sensor 10 input from
That is, if the paper feed sensor 10 is not turned on within a predetermined time even though the paper feed operation of the recording paper CP is started by the rotation of the paper feed roller 9, it is determined that the jam is a pickup error.

In the case of a jam due to a pickup error, a cleaning command is issued to the engine control unit 24 (S14). This is because in the case of a pickup error, there is no paper inside the machine, and even if the cleaning sequence is executed as it is, the engine will not be damaged.

Cleaning of the transfer roller 7 is carried out by a cleaning means, and the engine control section 24 operates the high voltage control section 29 upon receiving the cleaning instruction,
A potential having the opposite polarity to that at the time of transfer is applied to the transfer roller 7 to transfer the toner adhered on the transfer roller 7 to the photosensitive drum 1. The engine control unit 24 performs this processing at least one rotation of the transfer roller 7. The unnecessary toner transferred to the photoconductor drum 1 is removed by a normal cleaning process of the photoconductor drum 1 by the cleaning blade 8.

The cleaning at this time is performed for a shorter time than in the case of other jams. The reason why the cleaning time is short as described above is that in the case of a pick-up error, it is possible to detect in the initial stage of image formation, and therefore writing to the photosensitive member by the laser is hardly performed. If a pickup error is detected early, the laser does not write on the photosensitive member at all, and therefore cleaning may not be executed.

Further, the cleaning at this time does not require detection of the opening / closing of the cover. That is, in the case of a normal jam, it is necessary to remove the paper, and at that time, it is necessary to open and close the cover of the engine. However, in the case of a pick-up mistake, the paper does not remain in the machine, and thus the cover opening / closing work for the above purpose is unnecessary. In this way, in the case of a pickup error, the operator does not perform unnecessary work by cleaning without opening / closing the cover. Further, since it is not necessary to turn on and off the power when opening and closing the cover, it is possible to quickly recover from the jam.

When the cleaning of the transfer roller 7 is completed, the printer controller 22 causes the engine controller 24 to
In response, a jam cancellation request is output (S15). In response to this command, the engine control unit 24 receives the commands from the control units 25, 2 and 2.
8 to 30 are restarted under a predetermined operating condition, and the printing operation is restarted.

If the jam that has occurred is not a pick-up error (S13), the printer controller 22 displays a jam message indicating that a jam has occurred on the operation panel 23 and alerts the operator to eliminate the cause of the jam. (S16). When the cover of the laser printer is opened and the recording paper CP having the conveyance failure is removed (S
(17, S18), the printer controller 22 outputs a command to the engine control unit 24 to perform cleaning for removing the toner adhering to the transfer roller 7 (S19). In response to this command, the engine control unit 24
Performs the cleaning process of the transfer roller 7 in the same manner as described above. In the case of a jam other than a pick-up error, there is a possibility that a toner image has already been formed on the photosensitive drum 1 and the transfer roller 7 is heavily soiled. Therefore, the cleaning of the transfer roller 7 is performed in comparison with the time in step S14. Take a long time to do enough.

When the cleaning of the transfer roller 7 is completed, the printer controller 22 causes the engine controller 24 to
A jam release command is output to (S20), and
The jam display on the operation panel 23 is erased. The engine control unit 24 receives the jam clearing command and then the control units 2
5, 28 to 30 are restarted under predetermined operating conditions, and the printing operation is restarted.

As described above, in the laser printer according to the present embodiment, when the recording medium is not properly conveyed by the conveying means, that is, when a jam occurs, and when the jam is a paper feed pickup error, the cover opening / closing operation is a condition. Without performing the cleaning, the cleaning can be performed or the cleaning time can be shortened, or the cleaning can be resumed without the cleaning.

[0029]

As described above, according to the present invention, when the conveyance failure of the recording medium by the conveyance means occurs, the control means cleans the control according to the conveyance failure when the conveyance failure is a pickup error. On the other hand, if the conveyance failure is a jam in the middle of conveyance, the cleaning means is controlled to remove the toner on the transfer member onto which the toner on the photoconductor has been transferred. Since the cleaning is performed, it is possible to easily perform an appropriate cleaning process on the transfer member according to the type of conveyance failure.
In particular, when the conveyance error is a pick-up error, it is possible to quickly recover from the jam without the condition of opening and closing the cover.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a laser printer according to an embodiment of the present invention.

2 is a block diagram showing a configuration of a control system of the laser printer shown in FIG.

FIG. 3 is a flowchart showing a processing operation when a jam occurs in the laser printer shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum (photosensitive member), 7 ... Transfer roller (transfer member), 9 ... Paper feeding roller (conveying means), 1
0 ... Paper feed sensor (conveyance failure detection means), 12 ... Paper ejection sensor (conveyance failure detection means), 13 ... Paper ejection roller, 2
2 ... Printer controller (control means), 24 ... Engine control section (conveyance failure detection means, control means), CP ... Recording paper (recording medium).

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Claims (1)

[Claims] 1. A conveying means for picking up and conveying a recording medium one by one, a photoconductor on which a toner image is formed, and a recording medium which is brought into pressure contact with the photoconductor via the conveyed recording medium to record the toner image. A transfer member for transferring onto a medium, a cleaning unit for cleaning the transfer member, a conveyance failure detection unit for detecting a conveyance failure of the recording medium by the conveyance unit, and a conveyance failure of the recording medium by the conveyance failure detection unit. In the image forming apparatus having a control unit that operates the cleaning unit when is detected, the control unit is configured to detect the cleaning unit depending on whether the conveyance failure is a pickup error or a jam in the middle of conveyance. The image forming apparatus is characterized in that the controls for the above are different.