JPH07215533A - Image forming device and jam process control method thereof - Google Patents

Abstract

PURPOSE:To quickly resume the normal operation when a jammed sheet is removed while a device cover is not opened. CONSTITUTION:When a sheet does not reach the prescribed position in a prescribed period, a jam is judged to occur, and the jam error process is implemented. In step g1, the operations of a high-voltage system, an exposure system, and drive system are stopped. In step g2, whether a cover 22 is opened or not is judged with a cover switch. If the cover 22 is not opened, step g5 is implemented, and the level changes of sheet detectors SA, SB are checked to judge whether the jammed sheet is removed or not. In step g5, if there are level changes of the sheet detectors SA, SB, the jammed sheet is judged to be removed, the content of the travel position data corresponding to the jammed sheet is cleared, and the normal operation is resumed from the jam state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus that conveys a sheet to form an image thereon, and more particularly to a jam processing control method when the sheet remains in a conveying path and a jam occurs.

[0002]

2. Description of the Related Art In a general image forming apparatus, a plurality of sheets are stacked and stored in a sheet feeding cassette, the uppermost sheet is taken out one by one by a sheet feeding roller, and is fed to a registration roller via a conveyance guide. When the image arrives, the registration rollers are activated in synchronization with the printing start timing of the image forming unit using the electrophotographic process, the paper conveyance is restarted, a toner image is formed at a predetermined position on the paper, and then fixed. After passing the sheet, the toner image on the paper is fixed, and then discharged by the discharge roller to the outside of the machine, thus recording the desired image on the paper.

In such an image forming apparatus, it is important that each sheet is accurately conveyed to a predetermined position one by one at a predetermined timing. In order to monitor the traveling state of the sheet, the passage of the sheet is detected. A paper detector is installed in the middle of the transportation path.

For example, in the paper feed section, two sheets may be adsorbed and overlapped, or the paper feed roller and the paper may slip and the transport amount may be insufficient. In the case of overlap feeding, a paper detector provided in the vicinity of the upstream side of the registration roller measures the paper passage time, and when the paper passage time is larger than a predetermined value, it is determined that a paper conveyance abnormality, that is, a jam has occurred. Further, if the amount of conveyance is insufficient, it is similarly determined that a jam has occurred when the paper has not passed through the paper detector even after a lapse of a predetermined time after starting the paper feed roller.

On the other hand, when the paper detector provided upstream of the discharge roller in the conveying section cannot detect the passage of the paper within a predetermined time, it is judged that a jam has occurred.

When a jam occurs in the image forming apparatus, the normal operation is interrupted, and a jam waiting process for waiting for the jammed paper to be removed to the outside of the machine is executed, and a buzzer or a lamp blinks. Has announced the occurrence of a jam. In many cases, the user will open the device cover and then remove the jammed paper to eliminate the jammed state. Therefore, whether or not the image forming apparatus ends the jam waiting process and returns to the normal operation is determined by detecting the opening of the apparatus cover.

[0007]

However, in the conventional image forming apparatus, the jam standby processing is continued until the opening of the apparatus cover is detected. Therefore, for example, the jammed paper generated near the paper feed roller is pulled out to the upstream side of the conveyance. If the jam can be removed without removing the device cover, such as when it can be removed or when the jammed paper generated near the discharge rollers can be pulled out to the downstream side of the conveyance to be removed, it is possible to perform the jam recovery with a simple operation. Nevertheless, the jam waiting process will not end. Therefore, even if the user removes the jammed paper without opening the device cover, the user is forced to perform a wasteful work of opening and closing the device cover in order to return to the normal operation from the jam standby process. There is.

In order to solve the above-mentioned problems, an object of the present invention is to provide an image forming apparatus and a jam processing control method therefor capable of promptly returning to normal operation when the jammed paper is removed without opening the apparatus cover. Is to provide.

[0009]

According to the present invention, there is provided a paper feeding means for feeding a paper, an image forming means for forming an image on the paper fed from the paper feeding means, and the image forming means. A sheet discharging unit for discharging the sheet that has passed through the sheet, a sheet detecting unit installed at a predetermined position of a path along which the sheet travels, for detecting the passage of the leading edge or the trailing edge of the sheet, and detecting the opening of the apparatus cover. Cover opening detection means for
In the image forming apparatus, the image forming apparatus includes: a control unit that controls the paper feeding unit, the image forming unit, and the paper discharging unit, and that receives a signal from the paper detecting unit and the cover opening detecting unit. If the passage of the leading edge or the trailing edge of the sheet is not detected within a predetermined time, it is determined that a jam has occurred, and the jam waiting process is performed to wait until the jammed sheet is removed from the machine. In the image forming apparatus, if the signal of the sheet detecting means is inverted before the cover opening detecting means detects the opening of the apparatus cover, the jam waiting process is ended.

Further, according to the present invention, a first paper detecting means is provided between the paper feeding means and the image forming means, and a second paper detecting means is provided between the image forming means and the paper discharging means. It is characterized by being provided.

Further, according to the present invention, a sheet feeding unit for feeding a sheet, an image forming unit for forming an image on the sheet fed from the sheet feeding unit, and a sheet passing through the image forming unit are provided. A sheet discharging unit for discharging, a sheet detecting unit installed at a predetermined position of a path along which the sheet travels, for detecting passage of the leading edge or the trailing edge of the sheet, and a cover opening for detecting opening of the apparatus cover. A jam processing control method for an image forming apparatus, comprising: a detection unit, wherein when a leading edge or a trailing edge of a sheet is not detected within a predetermined time, it is determined that a jam has occurred, and the sheet causing the jam is detected as a machine. If the signal of the paper detecting means is inverted before the cover opening detecting means detects the opening of the apparatus cover while performing the jam waiting processing for waiting until it is removed to the outside,
A jam processing control method for an image forming apparatus, characterized in that the jam standby processing is ended.

[0012]

According to the image forming apparatus of the present invention, the control means is
If the passage of the leading edge or trailing edge of the paper is not detected within the specified time, it is determined that a jam has occurred, and the jam standby process is executed to wait until the jammed paper is removed from the machine. If the signal of the sheet detecting means is inverted before the opening detecting means detects the opening of the apparatus cover, the jam waiting process is ended. Therefore, when the user removes the jammed paper without opening the device cover, the user can quickly return to the normal operation, and the wasteful work of opening and closing the device cover is unnecessary.

Further, by providing the first paper detecting means between the paper feeding means and the image forming means, it becomes possible to detect the occurrence of a jam near the paper feeding means, and the jam occurs in the upstream direction of conveyance of the paper feeding means. It is possible to detect whether the paper has been removed. Further, by providing the second paper detection means between the image forming means and the paper discharge means, it is possible to detect the occurrence of a jam near the paper discharge means, and the jammed paper is discharged in the downstream direction of conveyance of the paper discharge means. It can be detected whether or not it has been removed.

According to the jam processing control method of the present invention, when the leading edge or the trailing edge of the sheet is not detected within a predetermined time, it is determined that a jam has occurred, and the jammed sheet is ejected outside the machine. The jam waiting process of waiting for removal is executed, and if the signal of the sheet detecting unit is inverted before the cover opening detecting unit detects the opening of the apparatus cover, the jam waiting process is ended. Therefore, when the user removes the jammed paper without opening the device cover, the user can quickly return to the normal operation, and the wasteful work of opening and closing the device cover is unnecessary.

[0015]

1 is a sectional view showing the construction of an image forming apparatus according to an embodiment of the present invention. A plurality of sheets are stacked and stored in the sheet feeding cassette 10, and a part of the bottom plate is biased upward by a spring or the like, so that the uppermost sheet can contact the sheet feeding roller 11 having an arc-shaped cross section. Then, the sheets are taken out one by one by the rotation of the sheet feeding roller 11 and run along the conveyance guide 12. Note that the paper transport path is indicated by a chain line in the figure. When the paper feed roller 11 rotates several times, the leading edge of the paper reaches the stopped registration roller 13. A sheet detector SA for detecting passage of the leading edge or the trailing edge of the sheet is provided near the upstream side of the registration roller 13.

Next, the registration roller 13 is synchronized with the printing start timing of the image forming section using the electrophotographic process.
To restart paper transport. The image forming unit has a photoreceptor 1 having a high electric resistance in the unexposed portion and a reduced electric resistance in the exposed portion, a primary charger 2 for uniformly charging the surface of the photoreceptor 1, and a photoreceptor. An exposure unit 3 that exposes the surface of the photosensitive member 1 on the basis of a printing signal to form an electrostatic latent image, a developing unit 4 that adheres toner to a charged portion of the photosensitive member 1, and a toner formed on the surface of the photosensitive member 1. Transfer device 5 for transferring images to paper
And a cleaner unit 6 for removing the toner remaining on the surface of the photoconductor 1.

When the sheet is conveyed by the registration rollers 13 and passes between the photoconductor 1 and the transfer device 5 along the conveyance guide 14, a desired toner image is formed on the sheet.
Further, the toner on the sheet is heated and melted by passing through the fixing device 16 along the transport guide 15, and is fixed on the sheet. Further, the sheet that has passed through the fixing device 16 is conveyed by a discharge roller 17, travels along a conveyance guide 18, and is discharged onto a sheet discharge tray 20 by a second discharge roller 19. A paper detector SB for detecting the passage of the front end or the rear end of the paper is provided near the upstream side of the discharge roller 17.

The image forming apparatus includes a housing 21 for accommodating each component, a cover 22 that can be opened and closed, and a cover switch SC that contacts a part of the cover 22, and detects whether or not the cover 22 is open. ing.

FIG. 2 is a block diagram showing the electrical construction of the image forming apparatus shown in FIG. The CPU (Central Processing Unit) 31 that executes control of the entire image forming apparatus includes a CPU 3
ROM (Read Only Memory) 32 for storing programs and data necessary for 1 to operate, and RAM (Random Access Memory) capable of writing and reading data
33, a motor 35 serving as a power source in the device, and a motor 3
Paper feed clutch 36 for connecting the output of No. 5 to the paper feed roller 11
A registration clutch 37 that connects the output of the motor 35 to the registration roller 13, a high-voltage power supply 38 that supplies a high voltage to the transfer device 5, and a fixing heater 39 incorporated in the fixing device 16.
A drive circuit 34 for driving the motor 35, the paper feed clutch 36, the registration clutch 37, the high-voltage power supply 38 and the fixing heater 39, and paper detectors SA, SB for detecting the passage of the leading or trailing end of the paper. A cover switch SC for detecting whether the cover 22 is open or not is connected. The CPU 31 includes a timer counter for measuring the elapsed time from a certain time. The RAM 33 is provided with a traveling position memory for storing the position of the sheet traveling in the apparatus.

FIG. 3 is a development view in which the configuration of FIGS. 1 and 2 is developed along the sheet conveyance path. The sheet runs from the right side to the left side in FIG. 3 along the alternate long and short dash line in the figure. When the paper feed clutch 36 is turned on and the paper feed roller 11 rotates, one sheet of paper is taken out and conveyed, passes over the paper detector SA including a combination of an actuator and a photocoupler, and the registration roller 13 To reach. Next, when the registration clutch 37 is turned on and the registration roller 13 is rotated, the sheet is continuously conveyed, and when the sheet reaches the transfer device 5, the high voltage power supply 38 operates to transfer the toner image of the photoconductor 1 onto the sheet. To be done. Next, the fixing heater 39 of the fixing device 16 is energized, and when the sheet passes through the fixing device 16, the toner image is fixed. The fixed paper passes over the paper detector SB including a combination of an actuator and a photo coupler,
It is discharged by the discharge roller 17.

FIG. 4 is a memory layout diagram showing the contents of the traveling position memory in the RAM 33 of FIG. 2, and FIG. 5 is an explanatory diagram showing the correspondence between the data of the traveling position memory and the actual sheet position. In the running position memory, running position data consisting of 1 byte (8 bits) is assigned corresponding to each sheet existing in the apparatus. For example, one sheet of paper is placed in the upper 4 bits (b7 to b4) of the running position data D1. The trailing edge position of the eye is stored, and the leading edge position of the first sheet of paper is stored in the lower 4 bits (b3 to b0).
The upper 4 bits of 2 store the trailing edge position of the second sheet, and the lower 4 bits store the leading edge position of the second sheet.

Next, the relationship between the traveling position data and the leading end position of the paper will be described. Hereinafter, “X” is an arbitrary value of 4 bits, and “h” means hexadecimal notation.

1) When the traveling position data D1 is X0h, it indicates a state where the paper is stored in the paper feed cassette 10 before the paper feed clutch 36 is turned on.

2) When the traveling position data D1 is X1h, the sheet feeding clutch 36 is turned on for the first time and the sheet starts traveling.

3) When the traveling position data D1 is X2h, the sheet feeding clutch 36 is set to 2 after the sheet has traveled to some extent.
The state in which the leading edge of the sheet is in front of the sheet detector SA after the second turning-on is shown.

4) When the traveling position data D1 is X3h, the state is shown in which the leading edge of the sheet reaches the registration roller 13 after passing the sheet detector SA until the registration clutch 37 is turned on.

5) When the traveling position data D1 is X4h, it shows the state after the registration clutch 37 is turned on until the sheet travels and a high voltage is applied to the transfer device 5.

6) When the traveling position data D1 is X5h, after the high voltage is applied to the transfer device 5, the leading edge of the paper is located upstream or downstream of the fixing device 16 and before the paper detector SB. Indicates the status.

7) When the traveling position data D1 is X6h, it indicates a state in which the leading edge of the sheet has passed the sheet detector SB and is in front of the discharge roller 17.

8) When the traveling position data D1 is X7h, it indicates that the leading edge of the sheet has passed the discharge roller 17.

Next, the relationship between the traveling position data and the trailing edge position of the paper will be described.

1) When the traveling position data D1 is 0Xh, it means that the trailing edge of the sheet is in front of the sheet detector SA after the sheet is stored in the sheet feeding cassette 10.

2) When the traveling position data D1 is 1Xh, it shows the state until the registration clutch 37 is turned off after the trailing edge of the sheet has passed the sheet detector SA.

3) When the traveling position data D1 is 2Xh, the transfer clutch 5 is turned off after the registration clutch 37 is turned off.
The state until the application of the voltage to the is finished is shown.

4) When the traveling position data D1 is 3Xh, it indicates a state in which the trailing edge of the paper is in front of the paper detector SB after the voltage application to the transfer device 5 is completed.

5) When the traveling position data D1 is 4Xh, it means that the trailing edge of the sheet is in front of the discharge roller 17 after passing the sheet detector SB.

6) When the traveling position data D1 is 5Xh, it indicates that the trailing edge of the sheet has passed the discharge roller 17.

The running position data D1 for the first sheet has been described above.
When the third sheet is continuously conveyed, the traveling position data D2 and D3 are written in correspondence with the leading end position or the trailing end position of the second and third sheets.

Next, the operation of the image forming apparatus will be described. FIG. 6 is a flowchart showing the overall operation of the image forming apparatus. First, when the power is turned on, an internal initialization process for initializing the data stored in the CPU 31 and the RAM 33 is performed in step a1, and the driving circuit 3 is executed in step a2.
4 and the operation initialization processing of each device are performed, and the standby operation for preparing the temperature rise of the fixing device 16 is performed in step a3.

FIG. 7 is a flow chart showing the standby operation of step a3 of FIG. First, in step b1, the CPU 31 determines whether or not a print signal is received from a host device (not shown). In step b2, preheating control for keeping the fixing device 16 at the standby temperature is performed and waiting is performed until the print signal is received. If a print signal is received, the process returns.

Returning to FIG. 6, in the next step a4, the printing preprocessing for preparing the printing operation is performed. FIG. 8 is a flowchart showing the printing preprocessing of step a4 of FIG. First, in step c1, the temperature of the fixing device 16 is set to a predetermined temperature during the printing operation, then in step c2, the driving of the motor 35 is started, the primary charger 2 is turned on in step c3, and the development is performed in step c4. The developing bias of the container 4 is turned on and the process returns.

Returning to FIG. 6, the printing operation is performed in the next step a5. FIG. 9 is a flow chart showing a schematic operation of the printing operation of step a5 of FIG. 6, and shows a typical example of a plurality of processing block units constituting the printing operation. First, at step d1, each operation such as data input, output or detection is performed, at step d2 the traveling position data of the paper stored in the RAM 33 is updated, and at step d3 the CPU 3
With reference to the count value of the timer counter 1, the system waits until a predetermined time has elapsed, and after the predetermined time has elapsed, shifts to the next processing block. A detailed concrete example of this printing operation will be described later.

Returning to FIG. 6, in the next step a6, it is determined whether or not the next print signal is received. If the next print signal is received, the process returns to step a5 to perform the next printing operation. If the next print signal has not been received, step a7 is entered.

FIG. 10 is a flow chart showing the operation of the post-printing process of step a7 in FIG. First, step e
At 1, it is determined whether the paper discharge is completed. Specifically, if the traveling position data of the relevant paper is 57h,
The sheet has been completely discharged from the discharge roller 17. When the sheet is discharged, the primary charger 2 is turned off in the next step e2, the developing bias of the developing device 4 is turned off in the step e3, and the driving of the motor 35 is stopped in the step e4 to return.

Returning to FIG. 6, when the post-printing process of step a7 is completed, the process proceeds to step a3 and the standby operation starts again. Thus, the initialization operation, the standby operation, the printing pre-processing, the printing operation, and the printing post-processing can be performed to form a desired image on the paper.

11 and 12 show step a in FIG.
6 is a flowchart showing a specific operation of the printing operation of No. 5. Here, the first sheet will be described. First, at step f1, it is determined whether or not the paper feed timing can be changed by looking at the paper feed timing change flag set in the jam error process described later. Immediately after the power is turned on or during the normal operation, the change flag is reset and the process proceeds to step f4. The steps f2 and f3 will be described later because they are related after the jam error processing.

Next, at step f4, the paper feed clutch 36 is turned on, and at step f5, the traveling position data D1 is 01h.
Is written, and the process waits until the time for turning on the paper feed clutch 36 for the second time in step f6. Next, at step f7, the paper feed clutch 36 is turned on again, at step f8, the contents of the traveling position data D1 is incremented by 1 to set it to 02h, and at step f9 until the time when the sheet detector SA performs the detection operation is reached. stand by.

Next, at step f10, it is judged whether or not the sheet detector SA detects the passage of the leading edge of the sheet, and if it cannot be confirmed, a jam error process is executed. When the passage of the leading edge of the sheet is confirmed, the content of the traveling position data D1 is incremented by 1 and set to 03h in step f11.

Next, in step f12, a print cueing process is performed in synchronism with the print start timing of the image forming section using the electrophotographic process, the registration clutch 37 is turned on in step f13, and the traveling position data D1 in step f14. +1 is added to the contents of to set to 04h, and step f
At 15, the process waits until the transfer device 5 is turned on.

Next, in step f16, the transfer device 5 is turned on, and in step f17, the content of the traveling position data D1 is increased by +1.
After adding and setting to 05h, it moves to the flowchart of FIG.

In step f18 of FIG. 12, the sheet detector SB waits until the time for performing the detecting operation. Next, in step f19, it is determined whether or not the sheet detector SB detects the passage of the leading edge of the sheet, and if it cannot be confirmed, a jam error process is executed. When the passage of the leading edge of the sheet is confirmed, the content of the traveling position data D1 is incremented by 1 and set to 06h in step f20.

Next, at step f21, the sheet detector SA waits until the time for performing the detecting operation. Then step f
In step 22, it is determined whether or not the sheet detector SA detects the passage of the trailing edge of the sheet, and if it cannot be confirmed, a jam error process is executed. After confirming that the trailing edge of the paper has passed, step f23
Then, the content of the traveling position data D1 is added by + 10h for 16h.
Set to.

Next, in step f24, the registration clutch 3
Wait until the time to turn off 7. Then step f25
Then, the registration clutch 37 is turned off in step f26.
Then, add + 10h to the contents of running position data D1 and 26h
Set to. Next, in step f27, the process waits until the leading edge of the paper reaches the discharge roller 17, and in step f28, the content of the traveling position data D1 is incremented by 1 and set to 27h. Next, in step f29, the process waits until the transfer device 5 is turned off, and in step f30, the content of the traveling position data D1 is added by +10 h and set to 37 h.

Next, in step f31, the sheet detector SB waits until the time for performing the detecting operation. Then step f
At 32, it is determined whether or not the sheet detector SB has detected the passage of the trailing edge of the sheet, and if it cannot be confirmed, a jam error process is executed. After confirming that the trailing edge of the paper has passed, step f33
Then, + 10h is added to the content of the driving position data D1 and 47h is added.
Set to.

Next, in step f34, the process waits until the trailing edge of the paper reaches the discharge roller 17, and in step f35, the content of the traveling position data D1 is added by + 10h to 57h, and the process returns to the main routine.

FIG. 13 is a flow chart showing the jam error processing of FIGS. 11 and 12. First, step g
In 1, the power supply of the high voltage system such as the primary charger 2 and the transfer unit 5 is shut off, the operation of the exposure unit 3 is stopped, and the operation of the drive system such as the motor 35, the paper feed clutch 36, the registration clutch 37 is stopped. To do.

Next, at step g2, it is judged using the cover switch SC whether or not the cover 22 is opened. When the user opens the cover 22 to remove the jammed paper, the process proceeds to step g3 and waits until the cover 22 is closed. Next, in step g4, the paper detectors SA and S
By looking at the level change of B or the like, it is determined whether or not the jammed paper is removed, and the process returns to step g2 and waits until the level of the paper detector SA, SB or the like changes.

On the other hand, if the cover 22 is not opened in step g2, the process proceeds to step g5 and step g4.
Similarly to the above, it is determined whether or not the jammed paper is removed by looking at the level change of the paper detectors SA, SB, etc., and step g2 is performed until the level change of the paper detectors SA, SB, etc. is made.
I will return to and wait.

If there is a level change of the paper detectors SA, SB, etc. in step g5, it is judged that the jammed paper has been removed, and the traveling position data corresponding to the jammed paper, for example, 1
If the first sheet is jammed, the contents of the traveling position data D1 are cleared and set to 00h to recover from the jammed state. Here, the paper detector S without the cover 22 being opened
Explaining an example in which the level change of A, SB, etc. occurs, 1)
When the paper is jammed near the paper feed roller 11 and the paper detector SA, the user pulls out the jammed paper from the paper feed opening to eliminate the jam, 2) near the paper detector SB and the discharge roller 17. When the paper jams, it is assumed that the user pulls out the jammed paper from the discharge opening to eliminate the jam. Thus step g4 or step g
After passing 6, the jammed paper has been removed.

When the jammed paper is removed without opening the cover 22 as described above, it becomes possible to quickly recover from the jam processing, and the wasteful work of opening and closing the apparatus cover becomes unnecessary.

Next, at step g7, whether or not the feeding operation of the next sheet has started, for example, when the first sheet is jammed, the content of the traveling position data D2 of the second sheet is other than 00h. If the next sheet is not fed yet, it means that the jam has been completely eliminated, and the process proceeds to step a3 in FIG. 6 to enter the standby operation for the next sheet.

On the other hand, if the feeding operation of the next sheet has started in step g7, whether or not the content of the traveling position data D2 corresponding to the next sheet is 03h or more in the next step g8, that is, It is determined whether the leading edge of the paper has already reached the registration roller 37 and the registration clutch 37 has completed the ON operation. If the content of the traveling position data D2 is 03h or more, the reuse of the next paper is abandoned in step g9. Then, it is judged that a jam of the next sheet has occurred, the sheet retention position is displayed on the display panel or the like to notify the user, and the process returns to step g2.

On the contrary, if the content of the traveling position data D2 is equal to or less than 02h in step g8, that is, if the next sheet feeding is started but the registration clutch 37 is not yet turned on, the next sheet is continued as it is. It is possible to use it. This is because the operation of the registration clutch 37 and the printing start timing of the image forming unit can be synchronized. Therefore, when the next sheet can be reused, it is necessary to newly set the paper feed timing interrupted by the jam, and the paper feed timing change flag is set in step g10, and then the process proceeds to step a3 in FIG. Then, the standby operation for the next sheet is started.

The reuse of the next sheet will be described below. After the standby operation and the printing preprocessing are executed in steps a3 and a4 of FIG. 6, the printing operation of step a5 is started. In step f1 of FIG. 11, if the paper feed timing change flag set in the jam error process of FIG. 13 is set, it is necessary to change the paper feed timing according to the position of the next paper that has already started feeding. is there. If the content of the traveling position data D2 of the next sheet is 01h in the next step f2, the first operation of the sheet feeding clutch 36 has already been completed, and the process proceeds to step f7. Next, at step f3, if the content of the traveling position data D2 of the next sheet is 02h,
Since the second operation of the paper feed clutch 36 has already been completed, the process proceeds to step f11. On the other hand, if the content of the traveling position data D2 of the next sheet is not 02h in step f3, the content is 03h, and the process proceeds to step f12.

If the next sheet has already started feeding at the time when the jam occurs, the next sheet can be reused by changing the sheet feeding timing according to the position of the next sheet. Therefore, it is possible to save paper resources and quickly perform a jam restoration process.

[0066]

As described above in detail, according to the present invention, when the jammed paper is removed without opening the device cover, it is possible to quickly return to the normal operation, which is a waste of opening and closing the device cover. No work required.

Further, it becomes possible to detect the occurrence of a jam near the paper feed means and the paper discharge means, and it is detected whether or not the jammed paper is removed in the upstream direction of the paper feed means and the downstream direction of the paper discharge means. Therefore, it is possible to increase the proportion of jams that can be returned without opening the device cover.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus that is an embodiment of the present invention.

FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus shown in FIG.

FIG. 3 is a development view in which the configurations of FIGS. 1 and 2 are developed along a sheet conveyance path.

FIG. 4 is a memory layout diagram showing the contents of a traveling position memory in RAM 33 of FIG.

FIG. 5 is an explanatory diagram showing a correspondence between data in a traveling position memory and an actual sheet position.

FIG. 6 is a flowchart showing the overall operation of the image forming apparatus.

FIG. 7 is a flowchart showing a standby operation of step a3 of FIG.

FIG. 8 is a flowchart showing the print pre-processing of step a4 in FIG.

FIG. 9 is a flowchart showing a schematic operation of the printing operation of step a5 of FIG.

10 is a flowchart showing an operation of a post-printing process of step a7 of FIG.

FIG. 11 is a flowchart showing a specific operation of the printing operation of step a5 of FIG.

12 is a flowchart showing a specific operation of the printing operation of step a5 of FIG.

FIG. 13 is a flowchart showing jam error processing of FIGS. 11 and 12;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Primary charger 3 Exposure part 4 Developing device 5 Transfer device 6 Cleaner part 10 Paper feed cassette 11 Paper feed roller 12, 14, 15, 18 Conveying guide 13 Registration roller 16 Fixing device 17, 19 Ejection roller 20 Ejection Paper tray 21 Housing 22 Cover 31 CPU 32 ROM 33 RAM 34 Drive circuit 35 Motor 36 Paper feed clutch 37 Registration clutch 38 High-voltage power supply 39 Fixing heater SA Paper detector SB Paper detector SC cover switch

Claims (3)

[Claims] 1. A paper feeding means for feeding a paper, an image forming means for forming an image on the paper fed from the paper feeding means, and a paper for ejecting the paper having passed through the image forming means. Paper ejection means, a paper detection means installed at a predetermined position of the path along which the paper travels, for detecting passage of the leading edge or the trailing edge of the paper, and a cover opening detection means for detecting opening of the apparatus cover. An image forming apparatus including: a control unit that controls the sheet feeding unit, the image forming unit, and the sheet discharging unit, and that receives a signal from the sheet detecting unit and the cover opening detecting unit, If the passage of the leading edge or the trailing edge of the sheet is not detected within a predetermined time, it is determined that a jam has occurred, and the jam waiting process is performed to wait until the jammed sheet is removed from the machine. At the same time, if the signal of the sheet detecting means is inverted before the cover opening detecting means detects the opening of the apparatus cover, the jam waiting process is ended. 2. A first paper detecting means is provided between the paper feeding means and the image forming means, and a second paper detecting means is provided between the image forming means and the paper discharging means. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. 3. A paper feeding unit for feeding a sheet, an image forming unit for forming an image on the sheet fed from the sheet feeding unit, and a sheet for ejecting the sheet that has passed through the image forming unit. Paper ejection means, a paper detection means installed at a predetermined position of the path along which the paper travels, for detecting passage of the leading edge or the trailing edge of the paper, and a cover opening detection means for detecting opening of the apparatus cover. In a method for controlling a jam of an image forming apparatus including, if the leading edge or the trailing edge of a sheet is not detected within a predetermined time, it is determined that a jam has occurred, and the jammed sheet is removed from the machine. If the signal of the sheet detecting means is inverted before the cover opening detecting means detects the opening of the apparatus cover, the jam waiting processing is ended until the jam waiting processing is executed. Jam processing method for controlling an image forming apparatus characterized by.