JP4463967B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that forms an image on a sheet such as a copying machine, a printer, or a facsimile, and particularly has a feature in sheet conveyance.
[0002]
[Prior art]
Examples of the image forming apparatus using the electrophotographic system include a copying machine, a printer, and a facsimile machine. A copying machine generally has a function of reading an image such as an original, and forms an image on a sheet based on the read image information. In recent years, a copying machine has a communication function or the like to send image information sent from the outside. Some have the ability to input. The printer generally forms an image on a sheet based on image information sent from an external device such as a computer. The facsimile apparatus generally has a function of reading an image such as a document and a communication function, sends the read image information to the outside, and forms an image on a sheet based on the information sent from the outside.
[0003]
A conventional image forming apparatus will be described with reference to FIG. The figure shows an example of a laser printer. A toner image is formed by a developing device 101 on a photosensitive drum 100 as an image carrier, and a transfer means 104 is transferred to a sheet fed by a pair of registration rollers 102 and a pair of pre-transfer rollers 103. To transfer the toner image. The sheet onto which the toner image has been transferred is guided to a fixing device 106 by a conveyance guide 105, and the image is fixed by heating and pressurizing, and then discharged outside the apparatus, thereby forming an image.
[0004]
In the above apparatus, it is necessary to remove a jammed sheet such as a paper jam during conveyance, and it is necessary to secure a space for jamming between the photosensitive drum 100 and the fixing device 106. Therefore, particularly when the distance between the photosensitive drum 100 and the fixing device 106 is short, the transfer unit 104 and the conveyance guide 105 are supported by the conveyance frame 107, and a rotation fulcrum 107a is provided on the upstream side of the conveyance frame 107 in the sheet conveyance direction, It is known to secure the space by rotating the conveyance frame 107 by rotating the handle 108.
[0005]
Here, the transfer guide 109, which is a guide member for guiding a sheet from the pair of pre-transfer rollers 103 to the photosensitive drum 100, has a mainstream in which guide members are fixedly attached above and below the sheet conveyance path. However, in consideration of the jam processing, there is also known a configuration in which one of the upper and lower guide members can be opened and closed.
[0006]
[Problems to be solved by the invention]
However, in the configuration in which the upper and lower guide members of the transfer guide 109 are fixedly attached as shown in FIG. 4, the sheet is damaged by pulling the sheet toward the front during the jam processing, and the sheet remaining in the transfer guide 109 is the next. In some cases, jamming occurs again during image formation.
[0007]
Further, in the configuration in which the transfer guide 109 is opened and closed, it is necessary to lift one of the guide members by hand at the time of jam processing, and there is a possibility that the unfixed image portion of the sheet may be touched and the hands and the surroundings may be stained. Further, if the operation of closing the lifted guide member is neglected, the guide member may come into contact with the photosensitive drum 100 and be damaged when the transfer guide 109 is returned to the normal position after the jam processing.
[0008]
SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that improves the operability of a transfer guide and improves jam handling and maintenance.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, a representative configuration of an image forming apparatus according to the present invention is disposed inside the apparatus main body, an image bearing member for bearing a toner image, transfer means for transferring the toner image on the sheet When a transfer guide for guiding the sheet to the transfer unit, while supporting the transfer means and the transfer guide, a transport frame which is rotatably arranged with a fulcrum in the sheet conveyance direction upstream side, the conveyor A shaft member movably attached to the frame, and the transfer guide is composed of a pair of guide members disposed above and below the sheet conveyance path, and one of the guide members is rotatable to the conveyance frame. mounted, and are biased in the other guide member with biasing means, in the course of the conveyor frame is rotated, one end of said shaft member on one of the guide members of the pair of guide members those In addition, the other end of the shaft member abuts on a member inside the apparatus main body, and the shaft member moves relative to the transport frame as the transport frame rotates, so that the pair of guide members It is characterized by opening .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment, FIG. 2 is a schematic configuration diagram illustrating a state in which a conveyance frame is lowered, and FIG. 3 is a schematic configuration diagram illustrating a state in which jam processing is performed. It should be noted that the dimensions, materials, shapes, relative positions, and the like of the components described in the following description are examples unless otherwise specified, and are not intended to limit the scope of the present invention.
[0011]
In this embodiment, a laser printer is used as the image forming apparatus. The laser printer shown in FIG. 1 emits a laser beam from a laser scanner (not shown) based on image information obtained from an external device, and irradiates the photosensitive drum 1 as an image carrier. As a result, a latent image is formed on the photosensitive drum 1, and the latent image is developed by the developing device 3 to form a toner image.
[0012]
On the other hand, sheets stored in a cassette (not shown) are separated and fed one by one, conveyed by the registration roller pair 4 and the pre-transfer roller pair 5, and sent to the nip between the photosensitive drum 1 and the transfer roller 6. The pre-transfer roller pair 5 includes a pre-transfer upper roller 5a disposed on the upper side of the sheet conveyance path and a pre-transfer lower roller 5b disposed on the lower side.
[0013]
The transfer roller 6 is supported by the transfer arm 7 and is urged against the photosensitive drum 1 by a spring 8 with a predetermined pressure. In this way, the transfer roller 6 is urged to the photosensitive drum 1 to form a transfer portion, and the toner image is transferred from the photosensitive drum 1 to the sheet at the transfer portion. Further, the photosensitive drum 1 is provided with a cleaner 2 to remove a toner image remaining on the photosensitive drum 1 after transfer, and the photosensitive drum 1 is used for the next image formation.
[0014]
A conveyance guide 9 is disposed on the downstream side of the transfer unit, and guides the sheet to a fixing device 11 as fixing means. In the fixing device 11, the sheet is heated and pressed to fix the toner image. The sheet is further conveyed and discharged outside the apparatus by a pair of discharge rollers (not shown), and image formation is completed.
[0015]
Here, the transfer roller 6, the transfer arm 7, and the conveyance guide 9, which are transfer means, are supported by the conveyance frame 12, and the conveyance frame 12 is rotated with respect to the apparatus main body by a rotation fulcrum 12 a provided on the upstream side in the sheet conveyance direction. It is arranged to be movable. The conveyance frame 12 is fixed in contact with a positioning portion (not shown) of the cleaner 2 by a pressure plate 13, and the transfer roller 6 and the conveyance guide 9 are arranged at predetermined positions with respect to the photosensitive drum 1. The pressure plate 13 is supported by a cam 15 fixed to the handle 14, and supported or released by rotating the handle 14.
[0016]
Further, a lower transfer guide 16 and an upper transfer guide 17 are arranged between the pre-transfer roller pair 5 and the photosensitive drum 1 as guide members constituting a transfer guide for guiding the sheet. The lower transfer guide 16 is fixedly attached to the transport frame 12. On the other hand, the upper transfer guide 17 is rotatably attached to the pre-transfer upper roller 5a of the pair of pre-transfer rollers 5, and is biased in a direction approaching the lower transfer guide by a spring 18 as a biasing means. Further, a protrusion 17 a is provided at the tip of the transfer upper guide 17 and on the transfer lower guide 16 side. Even when the transfer upper guide 17 is urged by the transfer lower guide 16, the protrusion 17 a abuts on the transfer lower guide 16. A gap for sheet conveyance is formed between the two.
[0017]
A shaft member 19 that is a moving member for opening and closing the transfer upper guide 17 is provided in the vicinity of the transfer guide pair of the transport frame 12 (in the longitudinal direction in the drawing). The shaft member 19 is attached to a hole (not shown) of the transport frame 12 so as to be movable in the rotation direction of the transport frame 12 (vertical direction in the drawing). One end of the shaft member 19 is configured to come into contact with the upper transfer guide 17 without coming into contact with the lower transfer guide 16, and by contacting the upper transfer guide 17, it resists the biasing force of the spring 18. Can be opened. Further, the other end of the shaft member 19 is extended below the transport frame 12, and when the transport frame 12 is rotated, it is attached to a double-sided upper plate 20 that is an upper plate of a double-sided re-transport unit (not shown) inside the apparatus body. It is configured to abut and move relative to the transport frame 12. The inside of the apparatus main body is not limited to the double-sided upper plate 20, but may be a bottom plate of the apparatus main body, a rib provided independently, or the like.
[0018]
An operation when performing jam processing in the image forming apparatus having the above configuration will be described. When a jam occurs, as shown in FIG. 2, the handle 15 is rotated in the counterclockwise direction in the drawing, so that the cam 15 is also rotated in the counterclockwise direction, and the pressure plate 13 is dropped accordingly. As a result, the support of the transport frame 12 is released and rotation about the rotation fulcrum 12a is started. At this time, the lower end of the shaft member 19 contacts the double-sided upper plate 20 and moves upward relative to the transport frame 12. As a result, the upper end of the shaft member 19 comes into contact with the upper transfer guide 17 and rotates by a predetermined amount around the pre-transfer upper roller 5a against the biasing force of the spring 18, so that the transfer guide pair is opened.
[0019]
In this state, a jammed sheet is fed to the fixing device side by rotating a knob (not shown) attached to the pre-transfer lower roller 5b counterclockwise. Then, as shown in FIG. 3, the entire sheet is positioned between the conveyance frame 12 and the fixing device 11, and can be easily pulled out to the front. At this time, since the lower transfer guide 16 and the upper transfer guide 17 of the transfer guide pair are open, the sheet is not damaged and remains, and there is no possibility of causing another jam.
[0020]
After the jam processing is completed, by rotating the handle 14 in the clockwise direction in the figure, the transport frame 12 can be rotated and supported again in the transportable state. At this time, since the end of the shaft member 19 is also separated from the double-sided upper plate 20, the shaft member 19 moves downward, and the transfer upper guide 17 is a position where the protrusion 17 a contacts the transfer lower guide 16 by the biasing force of the spring 18. Return to. As described above, since the transfer guide pair is also opened and closed as the transport frame 12 is opened and closed, there is no possibility that the photoconductor drum 1 will be damaged by forgetting to close the guide member.
[0021]
In addition, during regular maintenance, the transfer guide pair is also opened as the transport frame 12 is opened, so that the dirt adhering to the lower transfer guide 16 and the upper transfer guide 17 can be easily wiped off. Can be planned.
[0022]
【The invention's effect】
As described above, in the image forming apparatus according to the present invention, one of the transfer guides including a pair of guide members that guide the sheet to the transfer unit is rotatably attached to the transport frame, and the other has the biasing unit. In addition to improving the operability of the transfer guide, it is possible to reliably perform jam processing, cleaning, etc. The maintainability can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present invention.
FIG. 2 is a schematic configuration diagram illustrating a state in which a transport frame is lowered.
FIG. 3 is a schematic configuration diagram illustrating a state in which jam processing is performed.
FIG. 4 is a diagram illustrating a conventional image forming apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Cleaner 3 ... Developing device 4 ... Registration roller pair 5 ... Pre-transfer roller pair 5a ... Pre-transfer upper roller 5b ... Pre-transfer lower roller 6 ... Transfer roller 7 ... Transfer arm 8 ... Spring 9 ... Conveyance guide
11… Fixer
12… Conveying frame
12a… Rotating fulcrum
13… Pressure plate
14 ... handle
15… Cam
16… Transfer guide
17… Transcription guide
17a ... projection
18… Spring
19… Shaft member
20… Double-sided upper plate

Claims (1)

An image carrier disposed inside the apparatus body and carrying a toner image;
Transfer means for transferring the toner image to a sheet;
A transfer guide for guiding the sheet to the transfer means;
A transport frame that supports the transfer means and the transfer guide, and has a fulcrum on the upstream side in the sheet transport direction, and is rotatably disposed .
A shaft member movably attached to the transport frame,
The transfer guide includes a pair of guide members disposed above and below the sheet conveyance path, and one of the guide members is rotatably attached to the conveyance frame, and is urged by the urging means to the other guide member. It is,
While the transport frame is rotating, one end of the shaft member abuts on one guide member of the pair of guide members, and the other end of the shaft member abuts on a member inside the apparatus main body. The image forming apparatus , wherein the shaft member moves relative to the transport frame as the transport frame rotates to open the pair of guide members .

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