JP2605749B2 - Separation claw advance / retreat control device in electrophotographic apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention has a sheet forcible discharge function for forcibly discharging a sheet in a transport path when a sheet jam occurs in the transport path in the apparatus. Of the separation claw, which moves the separation claw forward and backward with respect to the latent image carrier in accordance with the sending cycle of the sheet to the transfer position based on the image forming cycle. The present invention relates to a control device.

2. Description of the Related Art In an electrophotographic apparatus such as a copying machine, a latent image formed on a latent image carrier such as a photosensitive drum is developed with toner, and the toner image is transferred onto a sheet supplied to a transfer position by a transfer unit. Transcribed. After the image transfer, the sheet on which the image has been transferred is peeled off from the latent image carrier by the charging action of the peeling corotron. Further, in general, a separation claw is provided at a subsequent stage of the peeling corotron, assuming that the sheet is not completely peeled off only by the charging action in the peeling corotron. The separation claw is to be in sliding contact with the latent image carrier to mechanically peel off the sheet that cannot be peeled off by the peeling corotron. Preferably, the sliding time is as short as possible. Therefore, the separation claw is controlled to move forward and backward with respect to the latent image carrier.

Conventionally, for example, in a copying machine, advance / retreat control of a separation claw is performed as follows.

The paper sent from the paper cassette is temporarily made to stand by at a registration gate, and the paper that has been made to stand by at a paper feed timing in accordance with the timing of an image forming cycle such as charging, exposure, and development on a photosensitive member serving as a latent image carrier is removed. Send to the transfer position. At this time, the timer function is enabled from the transmission timing from the registration gate, and the timing at which the leading end of the sheet 31 is expected to reach the position l1 before the separation claw position A as shown in FIG. Then, the separation claw is advanced to the photoconductor, and thereafter, the separation claw is controlled to be retracted from the photoconductor at a timing when the paper is expected to overlap the separation claw by l2. Therefore, the separation claw is kept in the advanced state for the time tt = (l1 + l2) / v from the timing when the leading end of the paper is at the front l1, and during that time, the separation claw was not separated from the photoconductor by the charging action of the separation corotron. The paper is peeled by the separation claw.

On the other hand, in this type of electrophotographic apparatus, for example, in the case of a copying machine, paper jam in an important part such as a fixing device or a photoconductor is processed by a system down, and the conveyance for a normal paper conveyance is performed. When a jam occurs in a route, there is a device having a function of forcibly discharging the sheet in the transport route as it is as a process at the time of abnormality. The processing in this case is performed by a system other than the transport system, for example, charging, exposure, development,
The process system for transfer, cleaning, and the like is stopped, and in that state, the transport system is enabled to forcibly discharge the paper staying in the transport path.

In a copying machine having such a paper forced discharge function,
When the sheet is discharged from the apparatus as it is based on the sheet forced discharge function, the control system related to the separation claw also goes down similarly to the normal process system, and the separation claw is retracted from the photoconductor. .

[Problems to be Solved by the Invention] By the way, as described above, an electronic device having a sheet forcible discharge function for forcibly discharging the sheet in the transport path when a sheet jam occurs in the transport path in the apparatus body. In a conventional separation claw advance / retreat control device employed in a photographic apparatus, when a sheet in a conveyance path is forcibly discharged based on the sheet forced discharge function, particularly, a sheet at a transfer position is a latent image. There is a possibility that the film cannot be peeled off while being adsorbed on the carrier.

This is because, when the sheet is forcibly discharged, the control for the separation claw is also reduced together with a system other than the conveyance system, for example, the separation corotron, and the separation claw is in a retracted state.

That is, the sheet is discharged in a state where the separation claw is retracted, but at the time when the sheet jam occurs, the sheet in the transfer process is not easily released from the close contact with the latent image carrier,
When the latent image carrier is transported by the movement of the latent image carrier due to forced discharge, it does not receive any peeling action.

When a small-sized sheet is targeted, the number of sheets sent out of the paper cassette for continuous image formation and staying in the conveyance path increases, so that the probability that the sheet stays in the transfer process when a sheet jam occurs is high, It becomes a problem.

Therefore, an object of the present invention is to make it possible for a sheet in close contact with a latent image carrier to undergo a peeling action when a sheet is ejected from the inside of the apparatus based on a forced sheet ejection function.

[Means for Solving the Problems] As shown in FIG. 1, the present invention relates to a method for controlling a sheet 1 in a transport path when a sheet jam occurs in the transport path in the apparatus.
In the electrophotographic apparatus having a sheet forcible discharge function A for forcibly discharging the sheet, the separation claw 2 is attached to the latent image carrier 3 in accordance with the sending cycle of the sheet 1 to the transfer position P based on the image forming cycle. It is assumed that the separation claw advance / retreat control device is configured to advance and retract B. In this device, the technical means for solving the above-mentioned problem is that the sheet 1 is moved inside the machine based on the sheet forced discharge function A. When it is detected that a sheet jam has occurred in the transport path in the machine body when the sheet is ejected from the printer, the advance holding means 4 for forcibly bringing the separation claw 2 into the advanced state with respect to the latent image carrier 3 is provided. It is provided.

Here, the “sheet forced discharge function A” refers to a function of forcibly discharging the sheet in the transport path when a sheet jam occurs in the transport path in the apparatus, as described above.

The “transport path in the machine” includes, for example, a sheet feed path, a sheet reversing path, a discharge path, a return path, and the like, as described in embodiments described later. When the sheet is conveyed at a position related to the image forming operation, such as in the fixing device or the lower portion of the photosensitive drum, or when the sheet is located in the sheet feeding system in the middle of the sheet being fed from the sheet cassette. Not included. In other words, the “conveyance path inside the machine” in the present invention means a case where the sheet is located on a path that moves only because the sheet is simply conveyed, and performs image forming operations such as fixing and transfer on the sheet. The path moving to perform the operation or the path moving to separate a plurality of stacked sheets one by one and feed the sheet from the sheet cassette corresponds to the “transport path in the machine” here. do not do.

[Operation] In a normal image forming process, the separation claw 2 is controlled to move forward and backward with respect to the latent image carrier 3 in accordance with a sending cycle of the sheet 1 to the transfer position P based on the image forming cycle.

On the other hand, a sheet jam occurs in the transport route inside the machine,
When the sheet 1 is forcibly ejected from the inside of the apparatus based on the sheet forced ejection function A, the advance holding unit 4 forcibly holds the separation claw 2 in the advanced state with respect to the latent image carrier 3. In this state, the sheet 1 forcibly discharged is separated from the latent image carrier 3 by the separation claw 2 which keeps the advanced state even if the sheet 1 is brought into close contact with the latent image carrier 3 and conveyed.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 is a diagram showing an example of an electrophotographic apparatus to which the separation claw advance / retreat control device according to the present invention is applied.

This is an example of a two-color copying machine. In FIG. 2, a mirror 13, 14, 15, 17, 18, 19 and a lens 16 are provided below a platen 11 together with an exposure lamp 12 along with an exposure lamp 12. An exposure optical system is disposed, and reflected light of the light emitted from the exposure lamp 12 on the surface of the original 10 on the platen 11 is reflected by mirrors 13, 14, 1
5, the photosensitive drum 2 via the lens 16 and the mirrors 17, 18 and 19
The exposure position is guided to 0. Around the photosensitive drum 20, a charging device 21, a first developing device 22a for red toner, a second developing device 22b for black toner, a transfer device 23, and a peeling corotron 24 are arranged to execute an image forming process. ,
Further, at the subsequent stage, a separation clog 25 and a cleaning device 26 are arranged. In addition, an erase lamp 27 for removing electricity in an inter-image portion of the photosensitive drum 20 is disposed at a stage preceding the first developing device 22a.

Focusing on the paper transport system, a paper reversing path (U-turn path) 3 and a paper feed transport path 32 following the paper reversing path (U-turn path) 3 from the paper cassette 30 to the transfer position (the transfer device 23 and the separating corotron 24 arrangement position). The toner image is transferred to the sheet supplied to the transfer position through these transport paths, and then the fixing device is transported through the transport path 35.
The image is sent to 36 where the image is fixed. The sheet on which the image has been fixed is further discharged to a tray 40 via a discharge conveyance path 37. On the paper supply side to the transfer position, a manual paper conveyance path 34 for conveying the manual paper to the paper conveyance path 32 is formed. A return transport path 38 for returning the sheet on which the image has been fixed once for copying to an intermediate tray (not shown) is formed, and a gate 39 moves the sheet between the discharge path 37 and the return path 38 according to a command from the control system. It is configured to perform distribution.

FIG. 3 is a block diagram showing a basic configuration example of a control system of the copying machine having the above structure.

In the figure, reference numeral 50 denotes a CPU for controlling the entire system, 5
1 is RAM for storing programs, tables, etc., 52 is CPU50
RAM that stores necessary data obtained as a result of the calculation in
The CPU 50, the ROM 51, and the RA 52 are bus-connected respectively. An operation signal from a key switch 55 provided on the operation panel and an output signal from a jam sensor 56 provided in each transport path are input to the CPU 50 via the input interface 53. Here, the jam sensor 56
Is composed of a transmission type optical sensor etc. set so as to sandwich the paper in the transport path, and compares the detection timing at each position that should be originally obtained in the series of image forming process with the actual detection timing. When the timings are significantly different, the CPU 50 recognizes that a sheet jam has occurred at the preceding stage of the sensor position. A control signal from the CPU 50 is supplied to a transport system 59 and a process system 60 such as charging, exposure, development, transfer, and cleaning on the photosensitive drum 20 via an output interface 54. The transport system 59 and the process system 60 are controlled. The CPU 50 also determines the separation claw 25 based on the sheet sending timing based on the image forming cycle.
A control signal is output to a drive circuit 57 of a solenoid 58 for moving forward and backward. The functions of the CPU 50 include a control function for the normal transport system and the process system (normal RUN mode), as well as an abnormality processing function when a sheet jam occurs. This abnormality processing function is divided into the following three modes.

… Normal cycle down: When a paper jam occurs due to misfeed in the paper feed system, a mode in which the paper remaining in the conveyance path at the time of the jam detection is discharged while executing a normal copy cycle… Shutdown: Fixing device 36 When a jam occurs at a position where a serious trouble may occur, such as the lower part of the photosensitive drum 20, etc., a mode in which the entire copying machine is stopped when the jam is detected: Blank paper discharge cycle down: paper reversing path 33, return When a jam occurs in a conveyance path such as the conveyance path 38, the manual paper conveyance path 34, or the like, a mode in which the paper remaining in the conveyance path at the time when the jam is detected is discharged without copying as it is Next, FIG. The operation will be described according to the flowchart shown in FIG.

When copy conditions such as the number of copies and density are set by the operation input with the key switch 55, and the copy is started, the output signal from the jam sensor 56 is monitored. Is done. That is, the paper transport system 59 and the process system 60 are both controlled according to a fixed image forming cycle, and the paper fed from the paper cassette 30 is fed at a predetermined paper feed timing via the paper reversal path 33 and the paper feed path 32. Supplied to the transfer position. And
After the image transfer, the image is sequentially discharged to a tray 40 via a conveyance path 35, a fixing device 36, and a discharge conveyance path 37. In the normal RUN mode, the separation claw 25 moves forward and backward at the timing in the positional relationship shown in FIG. 5 described above with reference to the timing at which the sheet is sent to the transfer position according to the image forming cycle. Is turned on and off.

If a jam occurs inside the machine during the above-described process, the position of the jam is determined based on the state of the output signal from the jam sensor 56. Here, if it is determined that the jam occurrence position is the feeding position (misfeed) of the paper cassette 30, the control shifts to the normal cycle down mode (). That is, the paper supply system is stopped to stop the new supply of paper, and the paper staying in each transport path is discharged to the tray 40 while performing a normal image forming process. In the normal cycle down mode, the separation claw 25 is controlled to advance and retreat as usual. When it is determined that the jam occurrence position is below the fixing device 36 and the photosensitive drum 20,
Shift to the shutdown mode (). That is, the entire copying machine is stopped simultaneously with the detection of the occurrence of the jam. In this state, the operator removes the sheet remaining on the transport path.

On the other hand, if it is determined that the jam occurrence position is on the return conveyance path 38 or the like, the flow shifts to the blank sheet discharge cycle down mode (). That is, the process system 60 and the like other than the transport system 59 are stopped, and the solenoid 58 is turned on so that the separation claw 25 maintains the advanced state with respect to the photosensitive drum 20. Then, in this state, the transport system 59 is driven together with the rotation of the photosensitive drum 20, and the paper remaining in each transport path is forcibly discharged to the tray 40 as it is. Even if the paper remaining in the transfer process at the time of the detection of the jam is conveyed in close contact with the photosensitive drum 20 in the process of the forcible discharge, the separation claw is in the advanced state.
The paper is peeled off from the photosensitive drum 20 by abutment with 25, and is further discharged to the tray 40 via the subsequent conveyance path 35, the fixing device 36, and the discharge conveyance path 37.

When a jam occurs, after the processing is executed in one of the above modes, the copying machine enters a restart standby state and waits.

As described above, in the present embodiment, in the blank paper discharge cycle down mode, the separation claw 25 is forcibly held in the advanced state with respect to the photosensitive drum 20 regardless of various timings. When forcibly discharging paper,
Even if the sheet is in close contact with the photosensitive drum 20, the sheet is reliably peeled and discharged to the tray 40.

Although the present embodiment has been described by taking a copying machine as an example, the present invention is of course applicable to other electrophotographic apparatuses such as a printer.

[Effects of the Invention] As described above, according to the present invention, the separation claw is forcibly advanced to the latent image carrier when the sheet is ejected from the body based on the sheet forced ejection function. Since the sheet is held, when the sheet is forcibly discharged, the sheet in close contact with the latent image carrier is always subjected to the separating action by the separation claw. Therefore, there is no danger that the sheet may not be peeled off when the sheet is attracted to the latent image carrier, and it is possible to prevent a trouble caused by the sheet being caught in the subsequent cleaning device in a copying machine or the like.

Further, the present invention is configured to include an advance holding means for forcibly setting the separation claw to the latent image carrier in a state where it is detected that a sheet jam has occurred in the transport path in the machine. As a result, when the sheet is discharged, the sheet that is in close contact with the latent image carrier can be surely peeled off by the separation claw, and the separation claw acts on the latent image carrier in addition to the normal image forming cycle. Can be minimized, such as when a sheet jam occurs,
Unlike when the separation claw is applied to the latent image carrier for a predetermined time immediately after the start of the image forming operation, the time during which the separation claw acts on the latent image carrier is not unnecessarily long, and the latent image carrier is Wear can be minimized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of the present invention, FIG. 2 is a diagram showing an example of an electrophotographic apparatus to which a separation claw advance / retreat control device according to the present invention is applied, and FIG. 3 is a basic configuration example of a control system. FIG. 4 is a flowchart showing the flow of the process, and FIG. 5 is a diagram showing the state of the normal separation claw advance / retreat control timing. [Explanation of Symbols] 1 ... Sheet 2, 25 ... Separation claw 3 ... Latent image carrier 4 ... Advance holding means 20 ... Photosensitive drum 30 ... Paper cassette 32 ... Sheet conveyance path 33 ... Sheet Reversing path 35 ... Conveying path 36 ... Fixing unit 37 ... Ejecting and conveying path 38 ... Returning conveying path 40 ... Tray 50 ... CPU 56 ... Jam sensor 58 ... Solenoid 59 ... Conveying system 60 ... Process system

Claims (1)

(57) [Claims] 1. An electrophotographic apparatus having a sheet forcible discharge function (A) for forcibly discharging a sheet (1) in a transport path when a sheet jam occurs in a transport path in an apparatus. In the separation claw advance / retreat control device, the separation claw advances and retreats (B) with respect to the latent image carrier in accordance with a sheet transfer to a transfer position of a sheet based on an image forming cycle. When it is detected that a sheet jam has occurred in the path, when the sheet (1) is ejected from the body based on the sheet forced ejection function (A), the separation claw (2) is moved to the latent image carrier. An advance / retreat control device for a separation claw in an electrophotographic apparatus, comprising an advance holding means (4) for forcibly entering an advanced state with respect to (3).