JPH0664792A - Paper conveyer for image forming device - Google Patents

Abstract

PURPOSE:To prevent surplus force from being applied to fed out paper by swivelably providing a guide plate corresponding to a loop formed in the paper, and separating the guide plate from a resist part in the case of feeding out the paper straightened, in a paper straightening device arranged in a part just before an image transcription part from a photosensitive unit drum. CONSTITUTION:In a paper straightening device 5 arranged in the upstream part of a photosensitive unit drum 2, a resist roller device 6 and a preresist roller device 9 are arranged through a predetermined space, so as to perform straightening action by forming a loop Pa in paper P between both the roller devices. A lower guide plate 13 for restricting the loop of the paper between both rollers is swivelably constituted through a rotary cam member 15, and in the case of feeding out the straightened paper, the lower guide plate 13 is swiveled so as to release pressing against the loop.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet aligning device for feeding a sheet toward an image carrier such as a photosensitive drum in an image forming apparatus such as an electrophotographic copying machine, and more particularly to a sheet aligning apparatus for forming a loop on the sheet. An image configured to perform a matching operation and prevent the guide plate from pressing the loop of the paper when the paper is fed by the registration roller device so that the aligned paper is normally conveyed. The present invention relates to a sheet conveying device of a forming device.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic system such as an electrophotographic copying machine or a printer device, a toner image formed on an image bearing member such as a photosensitive drum is transferred onto a sheet, and the toner image is transferred. The paper on which the image has been transferred is fixed through a fixing device to make a copy.
In the image forming apparatus, a sheet aligning device is arranged immediately in front of the image transfer portion from the photosensitive drum, and the sheet aligning device is composed of a registration roller device and a pre-registration roller device. Then, the leading end portions of the sheets conveyed in the sheet conveying path one by one from the sheet feeding device that feeds the cut sheets are locked by the stop means provided in the sheet aligning device, and a loop is formed for the stopped sheets. By forming the sheet, the reaction force of the loop of the sheet is used to perform the aligning action on the sheet.

After aligning the sheets as described above, the registration roller device is driven in synchronism with the toner image formed on the photosensitive drum to bring the sheet to the peripheral speed of the photosensitive drum. The toner image is transferred by sending the toner image in this state. As described above, as a means for forming a loop in the sheet in the sheet aligning device and aligning the sheets, for example, the actual open shovel 6
Devices such as those disclosed in Japanese Patent Publication No. 4-555 are known. In the above conventional example, a paper thickness detection sensor is arranged near the entrance of the paper aligning device, and the size of the loop is controlled according to the information on the thickness of the paper, so that the leading edge of thin paper or the like is controlled. So that no extra pressure is applied.

[0004]

In a sheet aligning device of a general image forming apparatus, a guide plate or the like is arranged above and below a portion forming a loop on a sheet, and when a loop is formed on the sheet. The protruding portion of the loop is in contact with the guide plate. However, in a general paper aligning device, the paper is aligned in a state where a loop is formed in the paper, and then the registration roller device and the pre-registration roller device provided in the paper alignment device are driven to feed the paper. At that time, the loop of the paper may slide on the guide plate. When the paper loop slides on the guide plate, the paper may not be fed normally, and the paper may be obliquely fed at the image transfer portion.

Therefore, in order to prevent an excessive pressure from being applied to the loop of the sheet in the state where the sheet is aligned with the sheet aligning device, for example, the actual opening 64-6.
It is also conceivable to use means as disclosed in Japanese Patent No. 5242 or Japanese Patent Laid-Open No. 57-70563. In the above-mentioned conventional example, means for pressing the loop of the sheet by the elastic body is arranged in the sheet aligning device, and by applying a pressing force of a predetermined value to the loop, the sheet aligning device applies the sheet. , It is possible to feed without skew feeding. However, when the loop is formed to align the leading end of the sheet with the sheet being fed obliquely, loops having different sizes may be formed in the width direction of the sheet. Then, if the loop is pressed by applying an even pressure with an elastic body, an inconvenient state such as a state where the sheet is obliquely fed occurs during the transfer of the toner image, and the copy quality is improved. The problem of lowering occurs.

[0006]

It is an object of the present invention to solve the above-mentioned problems of the conventional sheet aligning apparatus, in which a loop is formed on the sheets for alignment, and when the sheets are sent out by the registration roller device, An object of the present invention is to provide a sheet conveying device of an image forming apparatus that can prevent excessive pressing of a loop portion of a sheet by swinging a guide plate in a direction away from the loop portion.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a sheet fed from a sheet feeding device is guided by a pair of guide plates constituting a resist portion guide and is brought into contact with a stop member to form a sheet. A loop is formed to align the sheets, and the signal that the toner image is formed on the image carrier releases the contact of the sheet with the stop member and drives the registration roller device to direct it toward the image transfer unit. The present invention relates to a sheet aligning device configured to send out. In the present invention, a means for detecting the leading edge of the sheet is arranged upstream of the sheet aligning device, the amount of loops formed on the sheet is controlled based on information from the detecting means, and the registration is performed. One of the pair of guide plates constituting the unit guide is swingably provided via a hinge, and when the paper is sent toward the image transfer portion, the leading end of the paper nips with the registration roller device. After that, a mechanism for swinging the swingable guide plate is configured. Further, in the present invention, the driving means for swinging the guide plate may be constituted by a rotary cam member. Further, according to the present invention, a control means is provided for controlling the drive timing for swinging the guide plate by using a solenoid, and controlling the timing of driving the solenoid by following the opening / closing operation of the gate member. be able to.

As described above, the guide plate arranged in the sheet aligning device is swingably arranged, and the swinging mechanism is provided for the guide plate, and the aligned sheet is nipped to the registration roller device and sent out. Thus, since the mechanism for swinging the guide plate is provided, it is possible to simplify the accessory mechanism in the paper aligning device, and the device is not complicated. Then, when the aligned sheet is sent out, the pressing of the loop by the guide plate is canceled, so that an excessive pressing force does not act on the loop formed on the sheet, so that the sheet can be effectively fed. You can When a cam mechanism or solenoid is used to swing the lower guide plate of the registration section guide,
In accordance with the loop formation of the sheet, the swinging motion of the guide plate can be arbitrarily controlled, and the aligning action of the sheet can be dealt with.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet conveying device of an image forming apparatus of the present invention will be described with reference to the illustrated example. In the image forming apparatus 1 shown in FIG. 1, the image transfer section by the transfer corotron 3 is arranged on the photosensitive drum 2, and the sheet aligning apparatus 5 is arranged immediately in front of the image transfer section. In the sheet aligning device 5, a registration roller device 6 and a gate member 7 are arranged at a position close to the photoconductor drum, and a pre-registration roller is provided upstream of the registration roller device 6 with a predetermined interval. The device 9 is arranged. The gate member 7 is provided so as to be retractable from and into the paper transport path by a drive mechanism such as a solenoid 8.

Further, the sheet conveying device in the sheet aligning device is
It is composed of a delivery section guide 10 arranged between the registration roller device 6 and the photosensitive drum, and a registration section guide 11 arranged between the registration roller device 6 and the pre-registration roller device 9. A guide plate that constitutes a guide member regulates the movement path of the sheet.
Further, in the upstream part of the pre-registration roller device 9,
A sensor S for detecting the leading end of the sheet is arranged so that the sheet fed from a sheet feeding device (not shown) can be controlled for the subsequent conveyance action on the sheet based on the information detected by the sensor. There is.

In the registration section guide 11, an upper guide plate 12 and a lower guide plate 13 are arranged to face each other,
A mechanism that forms a loop Pa in a state of protruding downward with respect to the paper is configured between the roller devices arranged at a predetermined interval. Further, the upper guide plate 12 constituting the resist portion guide 11 is formed in a substantially linear shape in conformity with the downward loop formed on the sheet, and the lower guide plate 13 is configured to be curved downward. . Then, the registration portion guide 11 causes the paper P to loop Pa.
Allow the loop to project downward when forming the. The lower guide plate 13 provided on the resist portion guide 11 is supported at a downstream end portion of the resist portion guide via a hinge 14, and the lower guide plate 1 is provided.
3 at a predetermined position, the rotating cam member 15 and the spring 16
Is arranged, and constitutes a mechanism for swinging the lower guide plate 13 via a hinge by driving the rotary cam member.

In the sheet aligning device 5 of the present invention configured as shown in FIG. 1, the leading edge of the sheet fed by the sheet feeding device from the sheet accommodating device such as the sheet feeding tray is detected by the sensor S. The pre-registration roller device 9 introduces the sheet to the sheet conveying path of the sheet aligning device 5. At that time, the gate member 7 arranged immediately in front of the registration roller device 6 is stopped at the projecting position so as to block the movement path of the sheet, and the sheet P is locked to the gate member 7. It will be stopped in the state of being. Then, while the sheet is stopped by the gate member, the pre-registration roller device 9 is driven for a predetermined time to form a loop Pa on the sheet, and the leading end portion of the sheet is aligned.

When a toner image is formed on the photosensitive drum on the aligned sheets in the above-described state, the timing is adjusted to the time when the front end of the toner image on the photosensitive drum reaches the transfer position. , The solenoid 8 is driven to retract the gate member 7 from the locking position for the sheet. The leading end of the sheet held and held by the gate member is pushed into the nip position of the registration roller device 6 by the repulsive force of the loop, and is sent toward the image transfer portion by the registration roller device 6. With the leading end of the sheet nipped by the registration roller device 6,
In response to a command from the control device of the electrophotographic copying machine, the rotary cam member 15 is driven to swing the lower guide plate 13 via the hinge 14, and as shown in FIG.
The paper feed action is performed in a state where is not in contact with the paper loop Pa.

As shown in FIG. 2, when the rotary cam member 15 is driven to swing the lower guide plate 13, a spring 16 arranged between the lower guide plate and a frame (not shown) or the like. However, the action of assisting the swing of the lower guide plate can be exhibited. Therefore, the loop of the fed sheet is prevented from sliding on the lower guide plate, and the action of feeding the sheet loop toward the image transfer portion is performed without applying other force to the loop of the sheet. The operation of each component in the sheet aligning device shown in FIG. 1 is set as shown in the timing chart of FIG.

In the timing chart shown in FIG. 3, the sensor S arranged upstream of the pre-registration roller device 9 outputs a detection signal after detecting the leading edge of the sheet until the sheet has finished passing. Then, when the trailing edge of the sheet finishes passing the position of the sensor, the detection signal is turned off. In addition, the paper stop member constituted by the gate member 7 is held in a projecting position in advance so as to close the paper transport path, or the detection signal from the sensor S energizes the solenoid to move the gate member to the paper transport path. Project toward. Then, in a state where the leading end of the sheet is locked and held with respect to the gate member 7, the sheet is stopped until the information for forming the toner image on the photosensitive drum is input.

The pre-registration roller device 9 arranged at the entrance of the paper aligning device is driven for a predetermined time after the leading edge of the paper is stopped by the gate member 7 to feed the extra paper. By giving an action,
Make the paper form a loop. Then, when the additional feeding time set in the control unit has elapsed, the drive of the pre-registration roller device is interrupted, the signal of the toner image formed on the photoconductor drum is waited for, the drive is restarted, and the next sheet is fed. Is stopped by the gate member to form a loop and then stopped.

In addition to the gate member and the pre-registration roller device, the rotating cam member 15 is rotated halfway after a predetermined time has elapsed after a signal indicating that a toner image has been formed on the photosensitive drum is output. As shown in FIG. 2, the sheet is swung to a position away from the loop. Then, the sensor S detects the trailing edge of the sheet and, after a predetermined time has elapsed after the OFF signal is output, the sensor S is further rotated a half turn to return the lower guide plate to the position shown in FIG. 1 to form a loop. Correspond to. In the sheet aligning device 5 having the above-described configuration, the sheet aligning action is performed with the loop formed on the sheet, and when the sheet is sent to the image transfer unit, the lower guide plate causes the sheet loop. There is no need to apply a pressing action or the like. Therefore, it is possible to prevent the aligned sheet from being obliquely fed again due to the pressing force applied to the loop, and the transfer operation of the toner image on the sheet can be performed in a good state.

In the embodiment of the present invention described above, the device for performing the aligning action by locking the leading end portion of the sheet by the gate member has been described, but the swinging mechanism of the lower guide plate of the present invention is
It can also be applied to an apparatus that does not use a gate member as shown in FIG. In the sheet aligning apparatus shown in FIG. 4, the leading end of the sheet is temporarily stopped in a state of being projected into the nip position of the registration roller device 6, and the pre-registration roller device 9 performs additional feeding to form a loop. To do. Then, when the aligned sheets are sent out from the photosensitive drum 2 to the image transfer portion, the lower guide plate 13 is retracted from the position where the loop is pressed so that the loop is not adversely affected.

The lower guide plate 13 shown in FIG.
Then, an auxiliary guide plate 17 for pressing and regulating the loop of the sheet is provided at the end portion on the pre-registration roller device side. The auxiliary guide plate 17 is swingably supported at the upstream end of the lower guide plate 13 via a hinge 18, and a compression spring 19 is provided at the downstream lower part of the auxiliary guide plate 13.
Is provided. When forming a downward loop on the sheet, the auxiliary guide plate 1 is formed by the loop of the sheet.
It is possible to align the sheets by pressing 7 and exerting the action of pushing back the loop by the reaction force of the spring.

Therefore, as described above, when the auxiliary guide plate is additionally provided to the lower guide plate, it becomes possible to perform the sheet aligning operation in the sheet aligning device in a good state. Furthermore, when sending out aligned paper, the lower guide plate retracts from the position where it contacts the paper.
It is possible to prevent the sheet from being obliquely fed during the transfer of the image without giving an extra action to the sheet. It should be noted that providing another pressing member to the lower guide plate as shown in FIG. 4 can also be applied to the device shown in FIG. 1, and the mechanism of the auxiliary guide plate is also elastic. It is possible to use a member having an arbitrary configuration such as disposing a film member having the above or providing other pressing means.

As shown in the above embodiment, a rotating cam member is arranged with respect to the lower guide plate of the resist portion guide, and means for swinging the lower guide plate by rotating the cam member is provided. In addition, in the present invention, as shown in FIG. 5, it is also possible to dispose a driving means by a solenoid with respect to the lower guide plate to swing the lower guide plate. In the example shown in FIG.
In place of the rotary cam member, a drive mechanism by a solenoid 20 is provided, and a bracket 21 is attached to a lower guide plate 13 supported via a hinge 14 at a predetermined position on the swing side. The operation shaft of the solenoid 20 is connected to the valve 21.

A spring 23 is arranged to adjust the lowering position of the lower guide plate 13, and the lower guide plate 1
When the 3 is lowered by the solenoid 20, the spring 2
3, so that the lower position of the lower guide plate can be controlled. Then, the lower guide plate 1 shown in FIG.
When the solenoid 3 is swung to the lowered position by the solenoid 20, it is held at the position shown in FIG. Therefore, when the lower guide plate 13 is swung to the position shown in FIG. 6, the lower guide plate 13 does not interfere with the downward loop Pa of the sheet.

As shown in FIG. 5, when the swinging mechanism of the lower guide plate by the solenoid is incorporated, the operating timing of each operating device is set as shown in the timing chart of FIG. In the timing chart shown in FIG. 7, the sensor S arranged upstream of the pre-registration roller device 9 continues to output a detection signal after detecting the leading edge of the sheet until the sheet has finished passing, When the trailing edge of the sheet has passed the sensor position, the detection signal turns off. In addition, the paper stop member constituted by the gate member 7 is held in a projecting position in advance so as to close the paper transport path, or the detection signal from the sensor S energizes the solenoid to move the gate member to the paper transport path. Project toward. Then, in a state where the leading end of the sheet is locked and held with respect to the gate member 7, the sheet is stopped until the information for forming the toner image on the photosensitive drum is input.

The pre-registration roller device 9 arranged at the entrance of the paper aligning device forms a loop on the paper, and after a predetermined time elapses, the driving of the roller device is stopped, and the paper is moved. Holds the state that keeps the loop of. The solenoid for the lower guide plate 13 is driven in conjunction with the operation of each member, but the solenoid 20 arranged on the lower guide plate is operated by using the signal that the gate member 7 is closed, and the lower guide plate 13 is operated. 13 is swung in the retreating direction via a hinge. Then, the aligned sheets turn off the solenoid 20 and swing the lower guide plate 13 to a closed position in response to a signal that opens the gate and sends it out. Therefore, when the solenoid 20 is turned off, the lower guide plate is returned to the position shown in FIG. In the timing chart, the operation of opening and closing the gate member and the operation of outputting the image signal to the photoconductor drum are interlocked, and the writing of the image to the photoconductor drum is started. The operation of opening the gate member 7 and the operation of driving the registration roller device 6 to feed the paper toward the image transfer portion are performed at the same timing.

Therefore, when a solenoid is used to open and close the lower guide plate 13 of the registration portion guide 11, the structure of the opening and closing mechanism of the lower guide plate is simplified as compared with the case of a cam. However, depending on the structure of the electrophotographic copying machine, it may be necessary or mechanically necessary to provide an opening / closing means for the lower guide plate using a cam member to transmit the drive from another drive mechanism to the cam. . Also,
Depending on the configuration of the copying machine, it may be required to form the loop of the paper upward, but for those that form such an upward loop, the swing mechanism is arranged on the upper guide plate. As the swinging mechanism for the upper guide plate, the driving means as shown in the embodiment of the present invention can be provided. But,
In general, in an apparatus for forming a loop of a sheet upward, it may be possible to deal with the registration section guide by forming an allowance section for forming a loop on the upper guide plate by an opening. Therefore, in particular, when an upward loop is formed on a sheet and a swing mechanism for the guide plate is required, it is possible to dispose the swing mechanism for the upper guide plate as described above. .

[0026]

As described above, according to the present invention, the guide plate disposed in the sheet aligning device is swingably arranged, and the swing mechanism is provided for the guide plate to align the aligned sheets with the registration roller device. Since the mechanism for swinging the guide plate by the signal sent by nipping the sheet to the sheet aligning device is provided, it is possible to simplify the attachment mechanism of the sheet aligning device and not to complicate the device. Then, when the aligned sheet is sent out, the pressing of the loop by the guide plate is canceled, so that an excessive pressing force does not act on the loop formed on the sheet, so that the sheet can be effectively fed. You can Further, when another pressing member is provided for the lower guide plate of the present invention, a reaction force is applied to the loop formed on the paper so that the paper aligning action is favorably performed. You can Furthermore, when a cam mechanism or a solenoid is used to swing the lower guide plate of the registration section guide, in accordance with the loop formation of the paper,
The swinging motion of the guide plate can be arbitrarily controlled, the aligning action of the sheets can be dealt with, and the structure of the swinging mechanism of the guide plate can be simplified.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of a sheet aligning device of the invention.

FIG. 2 is a side view showing a state in which a lower guide plate is released to free a sheet loop.

FIG. 3 is a timing chart showing an operation state of each device in the paper aligning device of the present invention.

FIG. 4 is a side view of a second embodiment showing the configuration of the lower guide plate of the present invention.

FIG. 5 is a side view of a fifth embodiment showing the configuration of the lower guide plate of the present invention.

6 is an explanatory view of a state where the guide plate of FIG. 5 is opened.

FIG. 7 is a timing chart showing an operation state of each device in the paper aligning device of FIG.

[Explanation of symbols]

1 image forming apparatus, 2 photoconductor drums, 5
Paper aligning device, 6 registration roller device, 7 gate member, 9 pre-registration roller device, 10
Delivery section guide, 11 Registration section guide, 12
Upper guide plate, 13 lower guide plate, 14 hinge, 15 rotating cam member, 17 auxiliary guide plate, 20 solenoid, 23 spring.

Claims (3)

[Claims] 1. A sheet fed from a sheet feeding device is guided by a pair of guide plates constituting a registration portion guide, and a loop is formed in the sheet in a state of abutting against a stop member to align the sheet, By a signal that a toner image is formed on the image carrier, the contact of the sheet with the stop member is released, the registration roller device is driven, and the sheet is sent toward the image transfer unit. In the paper aligning device, a means for detecting the leading end of the paper is arranged upstream of the paper aligning device to control the amount of loop formed on the paper based on the information from the detecting means, Of the pair of guide plates constituting the unit guide, a guide plate arranged in the protruding direction of the loop of the paper is provided so as to be swingable via a hinge, and when the paper is sent toward the image transfer portion, tip A sheet conveying device of an image forming apparatus, wherein the swingable guide plate is swung after a section is nipped by a registration roller device. 2. The sheet conveying device of the image forming apparatus according to claim 1, wherein the driving means for swinging the guide plate is configured by using a rotating cam member. 3. A drive means for swinging the guide plate is performed by using a solenoid, and a control means for controlling the drive timing of the solenoid by following the opening / closing operation of the gate member is provided. The sheet conveying device of the image forming apparatus according to claim 1.