JP3325115B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine which has a rotatable branching pawl at a position where a transfer sheet is discharged outside the apparatus and a position where the transfer sheet is guided again inside the apparatus, and is capable of forming images on both sides of the transfer sheet. And an image forming apparatus such as a printer.

[0002]

2. Description of the Related Art For example, in a copying machine as an image forming apparatus, as shown in FIG. 9, a transfer paper P is rotated between a position where the transfer paper P is discharged outside the apparatus main body 1 and a position where the transfer paper P is guided again inside the apparatus. There is a type in which a movable branch claw 2 is provided in the paper discharge unit 3 so that an image can be copied (double-sided copy) on both sides of the transfer paper P.

When copying an image on only one side of a transfer sheet, the copying machine rotates the branch claw 2 between a first position indicated by a solid line and a second position indicated by a virtual line in FIG. The solenoid 4 is always controlled to be in the off state, and the branch claw 2 is set to the first position shown by the solid line. Therefore, the transfer sheet P after the image is copied by the image forming unit 10 is discharged onto the discharge tray 5 outside the apparatus.

When copying is performed by selecting the double-sided copy mode, the solenoid 4 is turned on at the time of copying the first surface (first surface), and the branch claw 2 is moved to the second position indicated by a virtual line. , The transfer paper P copied on the front surface is conveyed to the duplex unit 6, where the transfer paper P is stacked upside down.

Next, in order to perform copying on the back surface (second surface) of the transfer paper P, the solenoid 4 is turned off, and the branch claw 2 is brought to the first position shown by the solid line. The transfer paper P which has been re-fed and the image is also copied on the back side by the image forming unit 10 is discharged as it is onto the discharge tray 5 outside the apparatus.

In such a copying machine, when a plurality of copies are to be made in the double-sided copy mode in a normal case, a plurality of transfer papers are simultaneously transported on a transport path to achieve efficient copying. I'm trying to do it. For example, when the transfer paper is A4 size and is fed horizontally, about five transfer papers P1 to P5 are simultaneously transported on the transport path.

[0007]

However, in such a conventional copying machine capable of performing double-sided copying, when a plurality of double-sided copying is performed, the front side copying is performed.
If the transfer paper P5 or the like immediately after being fed from the paper feed cassette 8 shown in FIG. 9 other than the transfer paper passing through the branch claw portion causes a paper jam, a problem may occur.

That is, in the conventional copying machine, when such a paper jam occurs, the power supply to the main motor that drives the transfer paper conveyance system is automatically stopped, and the image forming operation of the apparatus is also stopped. At that time, since the solenoid 4 is also in a non-energized state (OFF), the branch claw 2 is at the first position shown by the solid line.

However, even if the power supply is stopped, the main motor for driving the transport system or the like stops rotating slightly after that due to the inertia force and then stops. Since the transfer paper is rotated, the transfer paper is conveyed during that time.

However, when the paper jam occurs, if the transfer paper P is being guided to the duplex unit 6 by the branching pawl 2 as shown in FIG. 10, the solenoid 4 is turned off in that state. As a result, the branch claw 2 is rotated from the position indicated by the imaginary line to the position indicated by the solid line, and the transfer paper P is pressed against the guide plate 11a by the leading end 2a, so that further progress is stopped.

In this state, as described above, when the rear side of the transfer paper P is conveyed in the direction of arrow A only while the main motor is rotating due to the inertial force, the transfer paper P is partially branched. 2 and rides on the upper side of the front end portion 2a, enters the gap formed by the front end portion 2a and the guide plate 11c, and stops when the main motor stops.

In this case, as shown by a virtual line in FIG. 10, when one of the guide plates 11a constituting the transport path 11 can rotate about the fulcrum 13, it is rotated. Even if it is opened, it is difficult to remove the transfer paper P that has entered the gap between the tip 2a of the branch claw 2 and the guide plate 11c.

Accordingly, in such a case, if the transfer paper is thin paper, the leading end is torn when the transfer paper is removed and it remains in the machine. If the transfer paper is thick paper, the rigidity of the paper itself is high. As a result, there is a possibility that the tip of the branch claw that is relatively easily deformed may be damaged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-described problems. An object of the present invention is to make it possible to easily remove a transfer sheet without damaging a transfer sheet or a branch claw located at a portion.

[0015]

According to the present invention, in order to achieve the above object, in the above-described image forming apparatus, a paper jam detecting means for detecting a paper jam of a transfer paper on a conveyance path, and a double-sided image forming apparatus. When the paper jam detecting means detects a paper jam during the operation of forming an image on the surface of the transfer paper, the motor stops driving after the power supply to the motor for driving the conveyance system is stopped even after stopping the power supply to the motor.
Means for keeping the solenoid on for a predetermined time which is equal to or longer than the time until the branch claw is in the second position.

The image forming apparatus further includes an opening / closing cover which is opened when the transfer paper having the paper jam has been taken out of the apparatus, and an interlock switch which operates by opening / closing the opening / closing cover. It is preferable to provide a means for turning on the solenoid in conjunction with the opening operation of the interlock switch when the opening / closing cover is opened after the elapse.

[0017]

[0018]

[0019]

According to the image forming apparatus configured as described above, if a paper jam of the transfer paper occurs on the transport path during the operation of forming an image on the surface of the transfer paper in the double-sided image formation, the paper jam detection means detects the paper jam. Detect.

When the paper jam detecting means detects a paper jam, the power supply to the motor for driving the transport system is stopped, the solenoid is turned on for a predetermined time, and the branch pawl guides the transfer paper into the machine again. Since the position 2 is maintained, even after the power supply to the motor is stopped, the branching pawl is rotated to the second position even if the transfer system continues to slightly transfer the transfer sheet due to inertial force. Therefore, when a paper jam occurs, the transfer paper positioned at the branch claw is always guided to the transport path on the side guided to the inside of the apparatus. Therefore, it can be easily taken out.

Further, there is provided an opening / closing cover and an interlock switch operated by opening / closing of the opening / closing cover.
If a means is provided for turning on the solenoid in conjunction with the opening operation of the interlock switch when the opening / closing cover is opened after a lapse of a predetermined time, if the opening / closing cover is opened after a lapse of a predetermined time, the opening / closing cover is linked to the opening state. Then, when the solenoid is turned on and the branching pawl takes out the transfer paper, the branching pawl moves to the second position where it is hard to obstruct, so that the work of removing the transfer paper located at the branching pawl can be easily performed. Become.

[0022]

[0023]

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a digital copying machine which is an image forming apparatus according to an embodiment of the present invention.

The digital copying machine, which is the image forming apparatus, is provided at a paper discharge section and guides the transfer paper to the outside of the apparatus body 1 outside the apparatus body. And a solenoid 4 that is rotatable to a second position indicated by an imaginary line that guides the divergent claw 2 to the first position in the off state and the second position in the on state. Have.

Each transport roller pair 7 for transporting the transfer paper
a, 7b and other transport roller pairs disposed on the transport path, and a motor 44 for driving a transport system such as the transfer device 14 having a belt transport unit.

In this digital copying machine, a solenoid 4 is used to form an image on the front surface (first surface) of a transfer sheet during duplex copying (duplex image formation) in which images are formed on both sides of a transfer sheet.
Is turned on, the transfer paper is again guided in the direction toward the duplex unit 6 in the machine by the branch pawl 2, and when an image is formed on the back surface of the transfer paper, the solenoid 4 is turned off and the branch pawl 2 The transfer paper is guided outside the machine and discharged.

At a substantially center of the apparatus main body 1 of the digital copying machine, a drum-shaped photosensitive member 15 constituting the image forming section 10 is provided rotatably at a constant speed in the direction of arrow C. Similarly, a charging charger 16 constituting the image forming unit 10
, A developing unit 17, a transfer device 14, a cleaning unit 18, and a discharging lamp 19 are provided. Above the image forming unit 10, an optical writing unit 35 is provided, and an image of the document set on the contact glass 36 and read by the scanner 37 is written on the photoconductor 15 by laser light.

Further, a fixing unit 21 is provided on the downstream side of the transfer device 14 in the conveyance direction, and the above-described branch claw is provided on a branch path immediately after the pair of fixing and discharging rollers 22 disposed on the downstream side. 2 is provided rotatably. Immediately before that, a sensor 38, which is, for example, a reflection type photosensor, for detecting the transfer sheet passing through the fixing sheet discharge roller 22 is provided.

A double-sided unit 6 used for performing double-sided copying is disposed below the image forming unit 10, and the transfer paper fed to the unit transport path 23 rotates in the direction of arrow E. The sheet is turned over by the reversing roller 24 and conveyed onto the double-sided tray 25 to be stacked.

The unit transport path 23 is provided with sensors (for example, reflection type photo sensors) 39 and 40 for detecting the transfer paper passing therethrough. The reversing roller 24 is also rotatable in the direction opposite to the direction indicated by the arrow E. The reversing roller 24 stacks the transfer paper, which is stacked on the double-sided tray 25 and whose leading end (the right side in FIG. Is rotated in the direction opposite to the direction indicated by the arrow E while being in contact with the peripheral surface of, and is fed again to the image forming unit 10.

A paper feed cassette 8 is detachably provided below the duplex unit 6, and a pair of transport rollers 7a and 7b feeds the transfer paper P fed by a paper feed roller 20 rotating in the direction of the arrow. It is transported to the provided vertical transport path 27.
In the vertical transport path 27, sensors (for example, reflection type photo sensors) 28 and 29 for detecting the transfer paper transported there are arranged at intervals, and the vertical transport path 27, the photoconductor 15 and A registration roller pair 31 is provided in the conveyance path between the rollers.

A sensor 32 similar to the sensor 28 is provided immediately before the pair of registration rollers 31.
The transfer paper fed from either side of the vertical transport path 27 or the manual paper feed unit 33 can be detected by the sensor 32. Reference numeral 12 denotes a fan for exhausting heat, which will be described in detail later.
Plays a role in discharging the air near the area where is disposed to the outside of the machine.

The digital copying machine has a paper jam detecting means for detecting a paper jam (jam) of the transfer paper on the transport path, and the paper jam during the operation of forming an image on the surface of the transfer paper by duplex copying. When the detecting means detects a paper jam, the power supply to the motor 44 is stopped even after stopping.
Control means 50 is provided for controlling the solenoid 4 to be kept ON for the predetermined time described above .

The paper jam detecting means includes a paper feed cassette 8
A paper jam of the transfer paper is detected based on whether or not the transfer paper fed from the printer has passed each of the sensors 28, 29, 32, 38, 39 and 40 within a preset time. The time for judging a paper jam in each case is determined in consideration of the arrangement position of the sensor and the transfer speed of the transfer sheet.

The control means 50 determines the paper jam based on the input timing of the ON / OFF signal input from each of the sensors. That is, in this embodiment, the sensors 28, 29, 32, 38, 39 and 4
0 and the control unit 50 function as a paper jam detection unit.

The control means 50 is a microcomputer, which stores a central processing unit (CPU) having various judgment and processing functions and various programs and fixed data necessary for controlling various operations at predetermined timings. It comprises a ROM as a stored program memory, a RAM as a data memory for storing input data and data processed by the CPU, and an input / output circuit (I / O).

In this digital copying machine, an opening / closing cover 52 that is opened when the transfer paper having a paper jam is taken out of the machine.
And an interlock switch (ILS) 53 that is activated by opening and closing the cover 52.

Next, a basic image forming operation of the digital copying machine will be described. In a one-sided copy mode in which an image is formed (copied) only on one side of the transfer paper, an original (not shown) is set on the contact glass 36 and a copy start key is pressed. Then, image information is read by the scanner 37, and a laser beam is emitted from the optical writing unit 35 based on the image information, and a latent image is written on the photoconductor 15. In addition, at the stage before this optical writing process,
The surface of the photoconductor 15 is uniformly charged by the charging charger 16.

In this way, a latent image is formed on the photoreceptor 15, and the latent image is developed by the developing unit 17 with toner to become a visible image. Thereafter, a transfer process is performed, and the transfer paper P is fed from the paper feed cassette 8 at a predetermined timing.
After it is once waited by the registration roller pair 31, it is conveyed again at a timing corresponding to the developed image on the photoconductor 15, and the developed image on the photoconductor 15 is transferred to the transfer device 14 to which the transfer voltage is applied.
Is transferred onto the transfer paper P by the transfer belt.

Thereafter, the transfer paper P is adsorbed on the belt portion of the transfer device 14 by static electricity, and
After the toner image is fixed there, the sheet is discharged onto the sheet discharge tray 5. On the other hand, the residual toner remaining on the photoconductor 15 after transferring the visible image is cleaned by the cleaning unit 18 and then the photoconductor 15 is removed.
Is uniformly discharged by the discharge lamp 19. By performing the above operation, one cycle of image formation is completed.

In the double-sided copy mode in which an image is formed on both sides of the transfer sheet, the transfer sheet which has exited the fixing unit 21 through the same process as in the case of the single-sided copy described above is indicated by a second dashed line in FIG. Is guided to the double-sided unit 6 by the branching pawl 2 rotating to the position, and when the sheet passes through the unit conveying path 23 and passes through the reversing roller 24, the sheet is turned over and stacked in the double-sided tray 25.

Then, the sheet is again fed from the duplex unit 6 by the reversing roller 24 rotating in the direction opposite to the arrow E, and the visible image is transferred to the back surface of the transfer sheet P through the above-described image forming process. Is guided by the branch claw 2 rotating to the first position shown by the solid line in FIG.

Next, the details of the operation of the paper discharge / reversal unit provided with the branch claws 2 will be described in detail. At the time of one-sided copying, the branch claw 2 is at the first position shown in FIG. 2, and at this time, the solenoid 4 (FIG. 1) is in the off state, and is brought into the rotation position shown by the urging force of a spring (not shown). I have. Therefore, the transfer paper conveyed by the fixing discharge rollers 22 is guided by the branch claws 2 to the pair of discharge rollers 43, and is discharged onto the discharge tray 5.

When copying the front side during double-sided copying, the branch claw 2 is in the second position as shown in FIG.
At this time, the solenoid 4 is in the ON state, and the transfer sheet conveyed from the fixing sheet discharge roller 22 is guided to the conveyance path side inside the machine where the pair of reverse relay rollers 45 are provided. Transported to

Next, when copying is performed on the back side of the transfer paper conveyed to the duplex unit 6, the branch claw 2 is in the first position as shown in FIG. 2 (the solenoid 4 is off). Accordingly, the transfer sheet re-fed from the duplex unit 6 and having the visible image transferred to the back surface is discharged onto the discharge tray 5 with the back surface facing upward.

Next, a description will be given of a paper jam process when a paper jam occurs during the front side copy of the transfer paper in the double-sided copy mode, which is a feature of the present invention. In this embodiment, when copying on the surface of the transfer paper in the double-sided copy mode as described above, the branch claw 2 is at the second position shown in FIG.
Here, if any one of the transfer papers other than the transfer paper passing through the branch claw 2 becomes a paper jam when, for example, five double-sided copies are being made, the control unit 50 shown in FIG.
The paper jam process is executed according to the routine shown in FIG.

First, it is determined whether or not a double-sided copy mode is set. If so, it is determined whether or not an operation of copying on the surface of the transfer paper is being performed. Determines whether a paper jam has occurred. If a paper jam has not occurred, the processing is terminated because it is not necessary to perform the paper jam processing. If a paper jam has occurred, the power supply to the motor 44 for driving the transport system is stopped, and the solenoid 4 is turned on in the next step. The process is continued after being kept on for a predetermined time t (several seconds).

As described above, when a paper jam occurs, the solenoid 4 is controlled so as to be kept on for a predetermined time t thereafter, so that the branch claw 2 remains in the predetermined state even after the power supply to the motor 44 is stopped. Until the time t, the transfer position is the rotation position for guiding the transfer paper to the duplex unit 6 (FIG. 1) while maintaining the second position shown in FIG.

Therefore, as shown in FIG. 5, the transfer paper P passing through the branching pawl 2 is stopped in the transport path 11 as shown in the figure, so that the solenoid 4 is turned off after the predetermined time t. As shown in the figure, the tip 2a of the branch claw 2 presses the guide plate 11a.

When the guide plate 11a is opened in the direction of arrow F as shown in FIG. 6, the transfer paper P pressed against the guide plate 11a by the tip 2a of the branch claw 2 becomes free. , Can be easily removed (the branch claw 2 is at the position shown by the phantom line).

As described above, according to this embodiment, FIG.
As described in the above, a paper jam occurs and the motor 4
After the power supply to the feeding pawl 4 is stopped, it is rotated by the inertial force, and the transport system continues to rotate slightly, so that a part of the transfer paper P rides above the leading end 2a of the branch claw 2 and guides the leading end 2a with the guide. There is no such thing as getting into the gap with the plate 11c.

Therefore, when copying is performed on both sides of the transfer sheet, even if a paper jam occurs on the transport path during the copy on the front side, the transfer sheet located at the branch claw 2 is not damaged. It can be easily taken out. Note that the predetermined time t is at least a time from when power supply to the motor 44 is turned off to when the motor 44 stops.

FIG. 7 is a flowchart showing a paper jam process according to the embodiment in which the processability of the paper jam is further improved. This embodiment is different from the embodiment of FIG. 1 only in the method of handling a paper jam, and the configuration of the mechanical part of the entire apparatus is the same as that of the embodiment of FIG. The description will be made using the reference numerals assigned to the respective parts in FIG. 1 as necessary.

In this embodiment, when the paper jam occurs, the solenoid 4 is turned on for a predetermined time t, and when the open / close cover 52 is opened after the lapse of the predetermined time t, the interlock switch 53 is opened. Then, the solenoid 4 is turned on. The control is performed by a microcomputer (not shown) similar to the control means 50 of the embodiment of FIG.
Is performed according to the paper jam processing routine shown in FIG.

That is, when the routine shown in FIG. 7 is started, the same processing as the paper jam processing described in FIG.
It is determined whether or not the predetermined time t has elapsed, and if it has not elapsed, it is waited as it is, and if it has elapsed, it is determined in step 7 whether or not the open / close cover 52 is open.

If it is not open, wait as it is,
When the user opens the opening / closing cover 52 to remove the transfer paper that has caused a paper jam, the interlock switch 53 is operated in conjunction therewith, so that the opening of the opening / closing cover 52 is determined based on a signal at that time. 4 is turned on, and in the next step 9, it is determined whether or not the open / close cover 52 is closed.

If it is not closed, the transfer cover having the paper jam is being removed while the cover 52 is still open.
When 2 is closed, the solenoid 4 is turned off in the next step 10, and the process is terminated.

According to this embodiment, when the opening / closing cover 52 is opened after the predetermined time t, the solenoid 4 is turned on, and as shown by a solid line in FIG. Since the transfer paper P having the paper jam has been removed, the branch claw 2 does not hinder the transfer paper P which has caused the paper jam as compared with the embodiment of FIG. It can be more easily removed.

The tip 2a of the branch claw 2 has an opening 11d.
Since it penetrates into the inside, it is possible to prevent the user from being injured by the tip 2a, and also to prevent the branch claw 2 from being deformed or damaged.

FIG. 8 is a flow chart for explaining a reference technique for improving the processing performance of a paper jam. In the description of this reference technology, the configuration of the mechanical part of the entire apparatus is the same as that of the embodiment of FIG. Description will be made using the attached reference numerals.

In this reference technique , when the paper jam detecting means similar to the embodiment of FIG. 1 detects a paper jam during the operation of copying on the surface of the transfer paper in the duplex copy mode, the power supply to the motor 44 is stopped. Means for continuing to keep the solenoid 4 on, and when the open / close cover 52 is closed while the solenoid 4 is on, the solenoid 4 is turned off in conjunction with the closing operation of the interlock switch 53. And means for performing the operation.

The means for keeping the solenoid 4 on and the means for turning off the solenoid 4 in conjunction with the closing operation of the interlock switch 53 are the same as the control means 50 described in the embodiment of FIG. The microcomputer (not shown) having the configuration functions. The microcomputer executes a paper jam process according to a routine shown in FIG.

That is, when the routine shown in FIG. 8 starts, the same processes as those in steps 1 to 4 in FIG. 7 are performed in steps 11 to 14, and the solenoid 4 is turned on in the next step 15. Next, in step 16, it is determined whether or not the open / close cover 52 is closed. If it is not closed, the transfer paper that has caused a paper jam has been removed with the open / close cover 52 still open. When the opening / closing cover 52 is closed, the solenoid 4 is turned off in the next step 17 to end the processing.

In this reference technology , when a paper jam occurs during the operation of copying on the surface of the transfer paper in the duplex copy mode, the power supply to the motor 44 is stopped, and the solenoid 4 remains in the ON state. Then, when the user opens and closes the open / close cover 52 in order to remove the transfer paper that has caused the paper jam, and closes the open / close cover 52 after the processing, the solenoid 4 is turned off by the signal of the interlock switch 53 linked therewith. According to this reference technique , the control is simpler than the paper jam processing of FIG.

By the way, if the apparatus is left in a state where the transfer paper has a paper jam, as in this reference technology , the solenoid 4 is kept on when a paper jam occurs. When the energization of the solenoid 4 is continued, the temperature of the solenoid 4 rises, and safety may be impaired. Therefore, in this reference technology , FIG.
However, a fan 12 for exhausting heat is provided as means for cooling the solenoid 4. The fan 12 also serves as a cooling unit for the fixing unit 21.

That is, in the image forming apparatus using the electrophotographic method, since the heat generated from the fixing unit 21 must be discharged to the outside of the machine, it is necessary to take advantage of the fact that the fixing unit 21 and the solenoid 4 are close in position. , Fixing unit 21
Fan 1 for discharging heat, which also serves to cool the solenoid 4
2 are provided. By doing so, it is possible to suppress an increase in cost for cooling the solenoid 4.

[0068]

As described above, according to the present invention, the paper jam of the transfer paper on the conveyance path during the operation of forming the image on the front side of the transfer paper in the mode of forming the image on both sides of the transfer paper. Occurs, and at that time, even if the power supply to the motor for driving the transport system is stopped and the transport system continues to slightly transport the transfer paper due to the inertial force, the branching pawl remains in the second position while the transfer paper is being transported. , The transfer paper is conveyed to the second position where it is easy to take out and is stopped, so that the transfer paper located at the branch claw portion can be easily taken out. Therefore, the transfer paper can be easily taken out of the apparatus main body without breaking the transfer paper or damaging the branch claws.

If a means is provided for turning on the solenoid in conjunction with the opening operation of the interlock switch when the opening / closing cover is opened after a lapse of a predetermined time after the power supply to the motor is stopped, a predetermined time can be provided. When the opening / closing cover is opened after elapse of the time, the solenoid is turned on, so that the leading end of the branch claw moves to the second position where it is hard to obstruct the transfer paper, so that the transfer located at the branch claw portion Paper can be easily removed.

[0070]

[0071]

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a digital copying machine which is an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a state in which a branch claw is at a first position during single-sided copying in the digital copying machine.

FIG. 3 is a schematic diagram showing a state where a branch claw is in a second position when copying is performed on the surface of a transfer sheet during double-sided copying with the digital copying machine.

FIG. 4 is a flowchart showing a routine relating to a paper jam process executed by a control unit 50 provided in the digital copying machine of FIG. 1;

FIG. 5 is a schematic diagram showing a transfer sheet stopped by being pressed down by a branch claw when a paper jam occurs during copying on the surface of the transfer sheet in the double-sided copy mode by the digital copying machine.

FIG. 6 is a schematic diagram showing a state in which the guide plate 11a is opened from the state of FIG. 5 and the transfer paper is taken out.

FIG. 7 is a flowchart illustrating a paper jam process according to an embodiment in which the processability of the paper jam is further improved.

FIG. 8 is a reference for improving the handling property of a paper jam.
It is a flowchart for demonstrating a technique .

FIG. 9 is a schematic configuration diagram showing an example of a conventional copier capable of performing double-sided copying.

FIG. 10 is a schematic diagram illustrating how a problem occurs when a paper jam occurs in a conventional copier capable of performing double-sided copying when the paper jam occurs.

[Explanation of symbols]

 2: Branch claw 3: Discharge part 4: Solenoid 12: Fan 21: Fixing unit 28, 29, 32, 38, 39, 40: Sensor 44: Motor 50: Control means 52: Opening / closing cover 53: Interlock switch

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G03G 15/00 106 G03G 15/00 106 526 526 21/00 398 21/00 398 (58) Investigation field (Int. Cl. ⁷ , DB name) B65H 29/60 B65H 5/06 B65H 7/06 B65H 85/00 G03B 27/52 G03G 15/00 106 G03G 15/00 526 G03G 21/00 398

Claims (2)

(57) [Claims] A branch claw disposed on a paper discharge unit and rotatable between a first position for guiding transfer paper to the outside of the machine and a second position for guiding the transfer paper back into the machine; A solenoid for moving the pawl to the first position and the branch pawl to the second position in an on state; and a motor for driving a conveyance system for conveying the transfer paper, forming images on both sides of the transfer paper When forming an image on the front surface of the transfer paper during double-sided image formation, the solenoid is turned on, and the transfer paper is guided again into the machine by the branch claws, and when an image is formed on the back surface of the transfer paper, An image forming apparatus that guides the transfer paper out of the machine and discharges the transfer paper by the branch claw with the solenoid turned off, wherein a paper jam detection unit that detects a paper jam of the transfer paper on a conveyance path; Form an image on the transfer paper surface That when the paper jam detecting means during operation detects jams, even after stopping the power supply to the motor
After the motor has continued to rotate due to inertial force,
Means for keeping the solenoid on for a predetermined period of time. 2. The image forming apparatus according to claim 1, wherein
An open / close cover that is opened when the transfer paper having caused the paper jam is taken out of the machine, and an interlock switch that is activated by opening and closing the open / close cover, wherein when the open / close cover is opened after the lapse of the predetermined time, An image forming apparatus comprising: means for turning on the solenoid in conjunction with an opening operation of the interlock switch.