JP3648027B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an image forming apparatus having a configuration for facilitating jam processing.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, and a facsimile, a configuration has been proposed for facilitating processing of a sheet remaining on a sheet conveyance path in the apparatus when a jam occurs. As a configuration for facilitating such a jam processing, there is a configuration in which a sheet in a sheet conveyance path on the upstream side of a registration roller is automatically discharged by opening a guide member in the conveyance path. Here, automatic paper discharge when a jam occurs is called a recovery operation.
[0003]
Contact Itewa the conventional image forming apparatus, when a jam occurs, whether or not to perform recovery operation, has been determined by whether the paper is in the registration unit. This is because when the paper is stopped due to a jam and the paper is positioned across the registration roller (stopped), the paper is returned to the front (upstream) of the registration roller by the recovery operation. This is to prevent adhesion of an unfixed image (unfixed toner) generated on the registration roller.
[0004]
[Problems to be solved by the invention]
However, since recent image forming apparatuses are required to have high productivity, the number of high-speed machines is increasing. Narrower paper interval during paper feeding is in high-speed machines, depending jam occurrence position and the conveying path (sheet feeding path) is multi no longer the paper to the resist portion is located, often not to the recovery operation It was. Not performing the recovery operation requires manual removal of the paper stopped at the registration unit, which is troublesome and cumbersome. That is, there are many cases where a function of recovery operation is provided but the function is not used, and therefore, there is a problem that processing when a jam occurs is not easy.
[0005]
The present invention solves the above-mentioned problems in a conventional image forming apparatus, and provides an image forming apparatus that can perform a recovery operation without being affected by a paper feed stage and a paper size and facilitates jam processing. Is an issue.
[0006]
[Means for Solving the Problems]
According to the present invention, there is provided a sheet feeding unit including a sheet feeding unit that separates and feeds sheets one by one according to the present invention, a registration unit that feeds a sheet in time with an image on an image carrier, Intermediate conveyance means disposed in the paper conveyance path upstream of the registration means, transfer means for transferring the image on the image carrier to the paper, and opening means for opening the guide member provided in the paper conveyance path upstream of the registration means A first paper detection means attached to the paper feed section, a second paper detection means attached to the intermediate transport means, a third paper detection means attached to the registration means, and at least the opening means and an image forming apparatus and a control means for controlling driving of the sheet feeding means and said register means and said intermediate conveyor means, when the paper jam occurs, the first or second sheet detection means a sheet And knowledge, and in a case where the third sheet detection means detects the paper, but before the leading edge of the sheet from the third sheet detection means detects the sheet reaches the transfer position, wherein, The driving of the paper feeding means is stopped, the opening means is operated, and the driving of the intermediate conveying means is continued to release the paper already fed from the paper feeding unit and in the conveying path upstream of the registration means. The problem is solved by executing a recovery operation for discharging to the space near the guide member .
[0007]
In order to solve the above-described problem, the present invention provides a control unit that performs normal feeding only on an upstream portion of the registration unit when a paper jam occurs when the first and second sheet detection units do not detect a sheet. It is proposed that the paper operation is continued for a predetermined time, and the recovery operation is executed when the first or second paper detection means detects the paper while the paper supply operation is continued.
[0008]
In order to solve the above problem, the present invention proposes that the control unit performs the recovery operation until the second sheet detection unit detects the trailing edge of the final sheet.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a schematic configuration of a copying machine according to an embodiment of the present invention. The copying machine shown in FIG. 1 includes an apparatus main body 1, a paper feeding device 2 mounted on the lower portion thereof, and an automatic document feeder 3 mounted on the upper surface of the main body. In the apparatus main body 1, an exposure apparatus 10 is disposed at an upper position, and a photosensitive drum 11 is disposed in a substantially central part of the main body.
[0010]
A charging device 12, an eraser 13, a developing unit 14, a transfer conveyance unit 15, a cleaning unit 16, and the like are disposed around the photosensitive drum 11 along the rotation direction to form an image forming unit. A fixing unit 17 is provided on the side of the transfer / conveying unit 15, and a double-sided tray 18 is provided below the image forming unit.
[0011]
In the present embodiment, the sheet feeder 2 mounted at the lower part of the apparatus body 1 is provided with four stages of sheet cassettes 21a to 21d. Paper feed units (paper feed means) 20a to 20d are provided corresponding to the respective paper feed cassettes. Paper feed sensors 22a to 22d are disposed on the roller portions of the paper feed units 20a to 20d. The sheets fed from the sheet feeding cassettes 21 a to 21 d by the sheet feeding units 20 a to 20 d are sent into the apparatus main body 1 through the conveyance path 23.
[0012]
In the apparatus main body 1, an intermediate roller 6 is provided in the conveyance path for sending the paper from the paper supply device 2 to the image forming unit, and a registration roller 4 is provided in front of the transfer unit 15. A registration sensor 7 is attached to the registration roller 4, and an intermediate sensor 8 is attached to the intermediate roller 6. An openable guide plate 5 for performing a recovery operation is provided on the conveyance path between the registration roller 4 and the intermediate roller 6.
[0013]
Here, the copying operation in the copying machine of this embodiment will be briefly described.
The documents D set on the document table of the automatic document feeder 3 with the image surface facing downward are sequentially sent leftward from the lower side, turned downward, and sent onto the contact glass (not labeled). Is stopped at a predetermined exposure position. It is also possible to manually set a document on the contact glass without using the automatic document feeder 3. The original D is scanned by the exposure device 10, and the original image is projected onto the photosensitive drum 11 (exposure process), and an electrostatic latent image is formed on the surface of the photosensitive drum 11. Note that the surface of the photosensitive drum 11 is uniformly charged by the charging unit 12 prior to exposure. The electrostatic latent image formed on the photosensitive drum 11 is erased by the eraser 13 in the non-image area, and then developed (visualized) by applying toner from the developing unit 14.
[0014]
On the other hand, the paper (recording paper) fed from each of the paper feeding cassettes of the paper feeding device 2 or the manual feed tray 24 provided on the side of the main body 1 is transferred to the toner image on the photosensitive drum 11 by the registration rollers 4. And is sent to the transfer position. The toner image is transferred onto the sheet by the transfer (conveyance) unit 15, and the sheet carrying the unfixed toner image is sent to the fixing unit 17 by the transfer conveyance unit 15. The unfixed toner image is heated and fixed by the fixing unit 17 and the paper is discharged.
[0015]
FIG. 2 is a perspective view showing a guide plate release mechanism for performing a recovery operation. This guide plate releasing mechanism opens the guide plate 5 disposed between the registration roller 4 and the intermediate conveyance roller 6. This figure shows a state in which the guide plate 5 is opened. Normally, the guide plate 5 held so as to close the conveyance path by the gate lock claw 9 is rotated as shown in the figure when the lock claw 9 is removed by the operation of the solenoid 19. Open automatically. That is, the sheet (solid line) conveyed by the intermediate roller 6 at the normal time (when closed) as indicated by the thick arrow is conveyed in the direction indicated by the broken line when the guide plate 5 is opened, and the space on the upper surface of the guide plate 5 (above the double-sided tray 18). It is discharged into the nearby cabin space.
[0016]
Next, control of the recovery operation when a jam occurs in the present embodiment will be described with reference to the flowchart of FIG. Note that the detection of the paper jam is the same as the conventionally known device, it is omitted.
[0017]
In the present embodiment, when a paper jam occurs, one of the paper feed sensors 22a to 22d or the intermediate sensor 8 detects the paper and the registration sensor 7 detects the paper, and the leading edge of the paper is transferred. If the position has not been reached, the recovery operation is executed.
[0018]
That is, in order to execute the recovery operation, it is a condition that the registration sensor 7 detects the sheet, and in the flowchart of FIG. 3, the condition that the registration sensor 7 detects the sheet is omitted. I'm.
[0019]
The recovery operation in the present embodiment is also performed under the condition that the sheet has not reached the transfer position after the registration sensor 7 detects the sheet. This condition is also omitted in the flowchart of FIG. Therefore, the flowchart of FIG. 3 shows that the recovery operation is executed when any of the paper feed sensors 22a to 22d or the intermediate sensor 8 detects the paper.
[0020]
Note that whether or not the sheet has reached the transfer position can be determined based on whether or not a predetermined time has elapsed after the start of registration roller driving, and can therefore be determined based on the driving timing of the registration roller. Of course, it goes without saying that the sheet has not reached the transfer position before the registration roller driving is started.
[0021]
Thus, in the present embodiment, the execution of recovery operation is judged based on the paper edge position, since the sheet (no image transfer sheet) discharged to the front register stroller, takes the hassle to jam Operability is improved.
[0022]
By the way, there are various aspects of paper jam. There is a case where a jam occurs because the detection timing of the paper is delayed for some reason (timing jam) instead of a jam caused by the paper being bent or damaged. For example, in the paper feed tray, when the paper call is somewhat delayed, even if the paper is transported without delay, it may be delayed to a predetermined transport timing. In such a case, the paper may be detected as a jam as a result of delaying the allowable timing at the sensor on the way. In addition, although the conveyance of the sheet itself is possible, it may be determined as a jam.
[0023]
In such a paper jam, if the jammed paper (the paper determined to be jammed) can be discharged by the recovery operation, the jam processing becomes easy and the operability is improved. Therefore, in this embodiment, when a paper jam occurs when the paper feed sensors 22a to 22d and the intermediate sensor 8 do not detect the paper, the normal paper feed operation is continued only for a predetermined time only in the upstream portion of the registration roller 4, When any of the paper feed sensors 22a to 22d or the intermediate sensor 8 detects a paper (while the paper feeding operation at the upstream portion of the subsequent registration roller 4 is continued), the recovery operation is performed.
[0024]
Conventionally, the recovery operation has not been performed when a timing jam has occurred in which the paper in the paper feed unit is not damaged. Therefore, if the paper feed tray (cassette) is pulled out when the device stops due to a jam, the paper is separated ( The paper is damaged due to the paper being stopped between the paper feed rollers).
[0025]
However, in this embodiment, when a jam occurs when the paper feed sensors 22a to 22d and the intermediate sensor 8 do not detect the paper, the normal paper feed operation is continued for a predetermined time only in the upstream portion of the registration roller 4 and the paper is detected. By performing the recovery operation, no paper is left in the paper feeding unit, so that it is not necessary to perform jam processing in the paper feeding unit, and operability can be improved. Further, it is possible to prevent damage to the paper due to separation of paper without providing a lock mechanism or the like for preventing the paper feed tray from being pulled out when a timing jam occurs.
[0026]
Further, in the conventional apparatus, when performing the recovery operation, the recovery operation is continued for a predetermined time calculated in advance corresponding to the maximum size sheet, and the operation is stopped. Therefore, in some cases, the paper cannot be completely discharged, resulting in a recovery failure.
[0027]
Therefore, in this embodiment, the execution of recovery operation, instead of doing only predetermined time (continues for a predetermined time), the intermediate sensor 8 performs the recovery operation until detecting the trailing edge of the paper motion Configure to stop. As a result, the sheet can be reliably discharged, and recovery failure can be prevented. Since the operation is stopped after the paper is discharged, power saving can be achieved. During continuous copying (printing), it is assumed that the blank paper transport operation is performed until the intermediate sensor 8 detects the trailing edge of the final paper (paper already fed).
[0028]
FIG. 4 is a flowchart showing the contents of the recovery operation.
As shown in this flowchart, the guide plate 5 is opened, and after waiting for the intermediate sensor 8 to change from on to off, the stop timer is started. When the stop timer reaches a predetermined time, the operation is terminated (motor off). On the other hand, the timer is counted up to a predetermined time, and if the intermediate sensor is not turned on (the timer is at the predetermined time), the operation is terminated. Further, when the intermediate sensor is turned on before a predetermined time, the stop timer is reset to wait for the intermediate sensor 8 to change from on to off. Thus, the recovery operation is performed until the trailing edge of the last sheet is detected.
[0029]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, since the sheet is discharged before the registration by the recovery operation , it is possible to facilitate the jam processing and improve the operability of the apparatus.
[0030]
Further, the resist roller upstream portion only normal paper feeding operation when a jam occurs for the predetermined period, by performing the recovery operation if it detects the paper therebetween, can prevent the problem associated with timing jam occurs in the paper feed unit Jam processing can be facilitated.
[0031]
Further, by performing the recovery operation until the trailing edge of the paper is detected, it is possible to reliably discharge the paper and prevent a recovery failure.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a copying machine according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a guide plate release mechanism for performing a recovery operation.
FIG. 3 is a flowchart showing control of a recovery operation when a jam occurs in the present embodiment.
FIG. 4 is a flowchart showing the contents of the recovery operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Copier body 2 Paper feeder 3 Automatic document feeder 4 Registration roller 5 Guide plate 6 Intermediate conveyance roller 7 Registration sensor (third paper detection means)
8 Intermediate sensor (second paper detection means)
DESCRIPTION OF SYMBOLS 10 Exposure apparatus 11 Photosensitive drum (image carrier)
15 Transfer conveyance unit 20a-d Paper feed unit (paper feed means)
21a-d paper feed cassettes 22a-d paper feed sensors (first paper detection means)
23 Paper transport path

Claims (3)

A sheet feeding unit including a sheet feeding unit that separates and feeds the sheets one by one, a registration unit that feeds the sheet in time with an image on the image carrier, and a sheet conveyance path upstream of the registration unit. An intermediate conveying means provided, a transfer means for transferring the image on the image carrier onto the paper, an opening means for opening a guide member provided in the paper conveying path upstream of the registration means, and an attachment to the paper feeding unit. First paper detection means, second paper detection means attached to the intermediate transport means, third paper detection means attached to the registration means , at least the opening means, the paper feed means, and the registration means. And an image forming apparatus having a control unit that controls driving of the intermediate conveyance unit ,
When a paper jam occurs, the first or second paper detection means detects the paper, and the third paper detection means detects the paper, and the paper is detected after the third paper detection means detects the paper. If the leading edge has not reached the transfer position, the control means stops driving the paper feeding means, operates the opening means and continues driving the intermediate conveying means, and has already been driven by the paper feeding unit. An image forming apparatus , wherein a recovery operation is performed to discharge the fed paper in the conveyance path upstream of the registration means to a space near the opened guide member . When a paper jam occurs when the first and second paper detection means do not detect the paper, the control means continues the normal paper feeding operation for a predetermined time only in the upstream portion of the registration means, and continues the paper feeding operation. 2. The image forming apparatus according to claim 1, wherein the recovery operation is executed when the first or second sheet detection unit detects a sheet. The image forming apparatus according to claim 1 , wherein the control unit performs the recovery operation until the second sheet detecting unit detects the trailing edge of the final sheet.

Images