JP3806556B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a plotter, and more particularly to an image forming apparatus including a fixing device having a separation member such as a separation claw for separating a sheet from a fixing roller.
[0002]
[Prior art]
In an image forming apparatus, for example, an image formed on an image carrier such as a photoconductor is transferred to a sheet, and a sheet carrying an unfixed image is fixed through a fixing device.
In general, a heat roller type fixing device has a fixing roller having a heat source and a pressure roller in pressure contact with the fixing roller, and a sheet carrying an unfixed image is sandwiched by a nip portion between the fixing roller and the pressure roller. It is fixed by heat and pressure while being conveyed.
[0003]
The fixing roller that is in direct contact with the image has a surface layer that is excellent in releasability because the paper is easily in close contact with the image. However, the paper is still in close contact, and the paper rolls around the fixing roller and the paper in the fixing device. Jam may occur.
For this reason, in general, a separation claw (separation member) that comes into contact with the surface of the fixing roller is provided in order to reliably separate the sheet from the fixing roller.
An exit side paper guide member is fixedly provided at a position facing the separation claw so as to guide the fixed paper.
[0004]
In Japanese Patent Application Laid-Open No. 5-289570, the fixing device is divided into upper and lower units, and the upper unit supporting the fixing roller is rotated in a direction perpendicular to the sheet conveying direction so that the fixing roller can be separated from the pressure roller. A technique for facilitating processing of a paper jam generated in a fixing device by greatly opening a paper conveyance surface is disclosed.
[0005]
[Problems to be solved by the invention]
Since the tip of the separation claw is sharpened and abuts against the surface of the fixing roller, there is no gap for the paper to enter between the separation claw and the fixing roller in the initial use of the image forming apparatus, and the paper is surely secured by the separation claw. After being separated from the fixing roller, the paper is guided along a paper conveyance path constituted by a separation claw and an outlet side paper guide member.
However, as the usage time of the image forming apparatus increases, the tip of the separation claw may wear over time or the toner may adhere to the tip of the separation claw and may float from the surface of the fixing roller.
[0006]
In such a state, the leading edge of the sheet may be caught between the leading edge of the separation claw and the fixing roller, and a jam may occur in which the sheet stagnate in a bellows shape.
The paper conveyance path between the separation claw and the corresponding exit-side paper guide member is formed narrow from the viewpoint of improving the guideability of the paper, and the exit-side paper guide member is fixedly provided. When the above-mentioned jam occurs, it is very difficult to take out the sheet from the fixing device.
In recent years, in order to shorten the sheet conveyance path for the purpose of improving the image forming speed, a sheet feeding unit, an image forming unit, and a fixing device are arranged in order from the lower side of the apparatus to the upper side. There are many image forming apparatuses in which the angle is substantially vertical. In such an image forming apparatus, there is little space around the fixing device in order to reduce the size of the entire apparatus, and this is in a situation that spurs the difficulty of the jam processing.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can easily perform bellows-like jam processing that occurs in a fixing device, and that can easily perform jam processing particularly in a type in which a sheet conveyance path is substantially vertical. .
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the fixing roller, the pressure roller in pressure contact with the fixing roller, the separating member for separating the paper from the fixing roller, and the paper conveying direction outlet side In an image forming apparatus including a fixing device having an exit-side paper guide member provided to face the separation member, the exit-side paper guide member is provided so as to be rotatable in a paper transport direction, and the fixing device is configured to feed paper. It is arranged so as to be transported substantially vertically, and has a lower frame for holding main fixing members such as the fixing roller and pressure roller, and an upper frame that covers the upper part of the apparatus and is detachable from the lower frame. In addition, the upper frame has a configuration in which a support portion for a rotation fulcrum of the outlet side paper guide member is provided.
[0009]
According to a second aspect of the present invention, in the configuration according to the first aspect, the outlet side paper guide member and the upper frame overlap each other in a vertical direction at a position where the outlet side paper guide member is aligned in the rotation axis direction. Is adopted.
[0010]
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect , in the portion where the exit side paper guide member and the upper frame overlap, the upper frame is positioned so as to block the inner side of the overlapping portion of the apparatus. It has a configuration with a vertical wall .
[0011]
According to a fourth aspect of the present invention, the fixing roller, the pressure roller that is in pressure contact with the fixing roller, a separation member that separates the paper from the fixing roller, and the separation member are provided facing the separation member on the exit side in the paper conveyance direction. In the image forming apparatus including the fixing device having the exit-side sheet guide member , the exit-side sheet guide member is rotatably provided in the sheet transport direction, and the sheet transport guide member is provided downstream of the exit of the fixing device. The paper conveyance guide member and the outlet side paper guide member each have a comb-shaped guide portion, and the outlet side paper guide member can be rotated to a predetermined position without opening the paper conveyance guide member. It has a configuration that is provided .
[0012]
According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third, or fourth aspect , a sheet feeding unit, an image forming unit, and the fixing device are provided in that order from the lower side to the upper side of the apparatus to convey the sheet. The path is formed substantially vertically, and the outlet side paper guide member is positioned at the upper part of the apparatus .
[0018]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, based on FIG. 1, an outline of the overall configuration of a copying machine as an image forming apparatus in the present embodiment will be described together with operations.
The sheets are fed one by one from the selected sheet feeding tray among the plurality of sheet feeding trays 2, 4, 6, 8 provided at the lower part of the apparatus to the registration roller pair 10 one by one from the top. The sheet is fed out, and an electrostatic latent image is formed on the photosensitive member 16 by the image writing device 14 based on the image information read by the image reading device 12. The electrostatic latent image is visualized as a toner image by the developing device 18.
The paper is temporarily stopped by the registration roller pair 10 and then conveyed upward at a predetermined timing and sent between the photoconductor 16 and the transfer roller to transfer the toner image.
[0019]
The sheet onto which the image has been transferred is further conveyed upward from the transfer unit and sent to the fixing device 22 where the image is fixed by heat and pressure. The sheet on which the image is fixed is discharged to the inner 1 bin tray 26 through the paper discharge device 24, or is sent to the relay unit 28, or is sent to the automatic duplex unit 30.
The paper sent to the relay unit 28 is discharged to a paper discharge tray 32 formed on the upper surface of the unit, or sent to a finisher 34 as a paper post-processing device. The paper sent to the finisher 34 is discharged to the paper discharge tray 36 without post-processing such as binding processing, or is discharged to the paper discharge tray 36 after post-processing.
The sheet conveyance path from the registration roller pair 10 to the fixing device 22 is set to be substantially vertical. After the sheet is sent upward from the fixing device 22, the direction is changed and the sheet is discharged to the inner 1 bin tray 26 and the like. In FIG. 1, reference numeral 38 denotes an auto document feeder, and 40 denotes a manual feed tray.
[0020]
As shown in FIG. 2, the heat roller type fixing device 22 includes a fixing roller 42, a pressure roller 44, a fixing separation claw 46 as a separation member, and the like. The fixing roller 42 has two heaters 48 inside. The thermistor 50 for detecting the surface temperature is in contact with the surface of the fixing roller 42.
The pressure roller 44 is in pressure contact with the fixing roller 42 by a pressure lever 52 and a pressure spring 54. A cleaning roller 56 is pressed against the pressure roller 44 by a spring 58.
A plurality (five in this embodiment) of fixing separation claws 46 are arranged at intervals in the axial direction of the fixing roller 42 (see FIG. 6). Each fixing separation claw 46 is urged by a spring 60, and its tip abuts against the surface of the fixing roller 42 with a predetermined pressure. In FIG. 2, reference numeral 62 denotes a thermal fuse, 64 denotes a static elimination needle, 66 denotes a paper discharge sensor filler, 68 denotes a paper discharge drive roller, 70 denotes a paper discharge driven roller, and 72 denotes a fullness detection sensor filler.
[0021]
Although not explicitly shown in FIG. 2, as shown in FIG. 3, the exit side for guiding the non-image surface of the paper in the case of single-sided copying is located at the position facing the fixing separation claw 46 on the paper exit side of the fixing device 22. A paper guide member 74 is provided to be rotatable in the paper transport direction. A paper conveyance guide member 76 is provided downstream of the fixing device 22 so as to be pivotable outwardly about a shaft 78.
The right cover 80 of the apparatus main body is rotatably provided around the shaft 82 as a fulcrum, and most of the substantially vertical sheet conveyance path is opened by opening the right cover 80. It has become.
When a jam occurs in the fixing device 22, first, the right cover 80 is opened, the paper transport guide member 76 is rotated outward to be opened, and then the jammed paper P is taken out. A position indicated by a solid line in FIG. 3 is an open position of the paper transport guide member 76 and the right cover 80.
[0022]
As shown in FIG. 4, the fixing device 22 has a two-part fixing frame composed of an upper frame 84 having a sheet conveyance outlet E and a lower frame 86. The fixing device 22 includes a fixing roller 42, a pressure roller 44, and the like. The main fixing component is assembled to the lower frame 86.
The exit side paper guide member 74 has a rotation shaft 74a as a rotation fulcrum extending in the axial direction of the fixing roller 42. The rotation shaft 74a is supported by the upper frame 84 and is rotatably provided.
[0023]
As shown in FIG. 5, a torsion coil spring 88 as an urging means is assembled to the rotating shaft 74a, and urges the exit side paper guide member 74 to the fixing separation claw 46 side. Each of the exit side paper guide member 74 and the upper frame 84 has overlapping portions 74b and 84a that overlap in the vertical direction at a position where the exit side paper guide member 74 is aligned in the rotation axis direction, and the overlapping portions 74b and 84a. The normal paper guide position (predetermined position) of the outlet side paper guide member 74 is positioned by the contact between them.
Further, in the vicinity of the overlap portion 84a of the upper frame 84, a vertical wall 84b is formed so as to close the overlap portions 74b and 84a on the inner side of the apparatus.
[0024]
By providing the vertical wall 84b as described above, it is possible to prevent the steam generated in the fixing device 22 from escaping from the exit side paper guide member 74 and the overlap portions 74b and 84a of the upper frame 84 to the outside of the device. Condensation of the paper discharge device 24 and the like located above can be prevented.
In particular, the vertical wall 84b is formed on the overlap portions 74b and 84a from the upper frame 84 side, so that a steam reservoir is formed. Therefore, the gap between the outlet side paper guide member 74 and the upper frame 84 is managed. It is not necessary to carry out strict, and even when the exit side paper guide member 74 and the upper frame 84 are warped due to fixing heat, it is possible to effectively prevent the vapor from going out of the fixing device 22.
[0025]
A plurality of ribs 74 c extending in the paper transport direction are formed on the paper guide surface side of the exit side paper guide member 74. The presence of the rib 74c reduces the friction between the sheet and the guide surface of the exit side sheet guide member 74, and improves the transportability.
Further, since the exit side paper guide member 74 can be easily rotated by hand so that the jam can be easily handled (see FIG. 7), the exit side paper guide is heated by the fixing heat. When a hand touches a wide area of the guide surface of the member 74, there is a risk of burns and the like, but such a concern is eliminated by the presence of the rib 74c. Since the fin-shaped rib 74c has good heat dissipation, even if the rib 74c itself is touched by hand, the heat of the guide surface is hardly transmitted.
[0026]
As shown in FIG. 6, the position of the rotation fulcrum S of the exit side paper guide member 74 is the normal line of the guide surface 74 d at the intermediate position of the length L in the paper transport direction of the guide surface 74 d of the exit side paper guide member 74. It is set on the upstream side in the paper conveyance direction with respect to G.
Further, the torque T that urges the exit side paper guide member 74 by the torsion coil spring 88 is F from the force that the exit side paper guide member 74 receives from the conveyed paper, and from the rotation fulcrum S to the application point of the force F. When the distance is r, it is set so as to satisfy the relationship of T−r × F> 0.
Although F varies depending on the type of paper, it is set so as to satisfy the above relational expression even when it is the largest value among the papers corresponding to the fixing device 22 and the copying machine.
[0027]
As shown in FIG. 5, the leading end of the rib 74c of the outlet side paper guide member 74 protrudes from the guide base 74e, whereby the leading end of the outlet side paper guide member 74 has a comb-shaped guide portion. is doing.
As shown in FIG. 9, the paper transport guide member 76 also has a plurality of ribs 76a, and a comb-shaped guide portion is formed. The rib 74c of the exit-side sheet guide member 74 and the rib 76a of the sheet transport guide member 76 are formed at positions that do not interfere with each other, and the exit-side sheet guide member 74 can be moved to a predetermined position without opening the sheet transport guide member 76. It is provided to be rotatable.
[0028]
Next, a fixing operation and a jam processing operation will be described.
As shown in FIG. 10, the sheet P on which the image has been transferred by the image forming unit of the copying machine is sent into the fixing device 22 from the entrance guide portion 90 opened in the lower frame 86 of the fixing device 22, and the fixing roller 42. The image is fixed by heat and pressure.
Normally, the sheet P on which the image has been fixed is separated from the roller surface by the curvature of the fixing roller 42, and is discharged out of the fixing device 22 through the outlet formed in the upper frame 84 and the outlet side sheet guide member 74. At this time, depending on the conveyance state of the paper P, the leading edge of the thin paper or the like may be discharged along the conveyance guide 84c (FIG. 4) formed by the upper frame 84 on the image surface side, or a strong paper such as thick paper In P, the leading end of the sheet may be discharged along the exit-side sheet guide member 74 on the non-image surface side.
[0029]
As described above, the exit-side sheet guide member 74 is rotatably supported by the upper frame 84. However, even when the sheet P is discharged along the exit-side sheet guide member 74, the normal conveyance is performed as described above. The exit-side sheet guide member 74 does not move with the force of the sheet P, and the conveyance of the sheet P can be guided well.
When the paper P cannot be separated only by the curvature of the fixing roller 42, such as a thin paper or a paper P on which many images are formed near the leading edge of the paper, the paper P is discharged so as to be wound around the fixing roller 42 and fixed. Separation is performed by a fixing separation claw 46 that is in contact with the roller 42.
[0030]
In this case, if the tip of the fixing separation claw 46 is worn or a lot of toner or the like is accumulated at the tip of the nail and the tip of the nail is floating from the surface of the fixing roller 42, the leading edge of the sheet is fixed to the fixing separation claw 46 And the fixing roller 42 may be jammed.
Further, when a jam occurs downstream of the fixing device 22 during continuous copying, the succeeding paper P may catch up with the previous paper P at the exit portion of the fixing device 22.
Since it takes a certain time from the occurrence of the jam until the apparatus stops, in such a jam, the paper P continues to be fed into the fixing device 22 even after the jam occurs, and the paper P is accordion-like at the exit portion of the fixing device 22. If the paper length is short, such as A4 landscape paper, the trailing edge of the paper may enter the fixing device 22.
[0031]
At this time, the sheet P is pressed over almost the entire guide surface of the exit-side sheet guide member 74 while forming a bellows shape at the exit of the fixing device 22. This pressing force is larger than the force acting during normal conveyance.
Since the position of the rotation fulcrum S of the exit-side sheet guide member 74 is set as described above, the exit-side sheet guide member 74 is rotated in the opening direction by the force of the sheet P, so that the exit portion of the fixing device 22 Space becomes wider.
As a result, there is a space for the paper P to escape, so that the paper P becomes easier to process and stops compared to the conventional configuration in which the exit-side paper guide member 74 is fixed. That is, the complicated entanglement of the jammed paper due to the absence of escape space is greatly reduced.
Since the exit side paper guide member 74 and the paper conveyance guide member 76 of the fixing device 22 are formed in a comb-teeth shape at each intersection, the normal operation state where the jam does not occur, that is, the right cover 80 is attached. Even when the paper transport guide member 76 is opened and the paper transport guide member 76 is not opened, the exit side paper guide member 74 does not interfere with the paper transport guide member 76 and cannot be fully opened.
[0032]
When the jam processing is performed, the right side cover 80 and the sheet conveyance guide member 76 of the copying machine main body are opened, and the exit side sheet guide member 74 that is half open by the pressing force of the jam sheet from above the fixing device 22 is maximized. The jammed paper can be pulled out as much as possible.
When the leading edge of the paper is caught between the fixing separation claw 46 and the fixing roller 42, it is very difficult to pull out the jammed paper with the configuration in which the conventional exit-side paper guide member is fixed. In the embodiment, the exit side paper guide member 74 is rotated to widen the exit portion of the fixing device 22 so that a finger is inserted to remove the leading end of the paper from between the fixing separation claw 46 and the fixing roller 42 and pull out the jammed paper. be able to. Immediately after the jam occurs, the heat of the fixing device 22 causes the guide surface 74d side of the exit side paper guide member 74 to be hot. However, as described above, the guide surface 74d is formed with a plurality of ribs 74c. The heat is difficult to be transmitted to your hands.
[0033]
After the jammed paper is removed, the exit-side paper guide member 74 is automatically returned to a predetermined position for guiding the normal paper by the biasing force of the torsion coil spring 88, so that a trouble due to the operator forgetting to return is prevented. .
During maintenance of the fixing device 22, the upper frame 84 is removed from the lower frame 86, but since the exit side paper guide member 74 is assembled to the upper frame 84, it can be removed as a whole, improving maintainability. Can be made.
[0034]
【The invention's effect】
According to the first aspect of the present invention, since the exit-side paper guide member is provided so as to be rotatable in the paper transport direction, the exit of the fixing device is used when processing the accordion jammed paper in the fixing device. Since the portion can be largely opened, it is possible to easily perform jam processing that occurs in the fixing device.
Further, the sheet caught on the separating member can be easily removed without disassembling the fixing device.
In addition, the fixing frame of the fixing device has a two-part configuration including a lower frame that holds main fixing components such as a fixing roller and a pressure roller, and an upper frame that covers the upper portion of the device and is detachable from the lower frame. Since the upper frame has a support portion for the rotation fulcrum of the exit side paper guide member, the exit side paper guide member can be attached to and detached from the fixing device at the same time as the upper frame, thereby improving the maintainability of the fixing device. be able to.
[0040]
According to the second aspect of the present invention, the exit-side paper guide member and the upper frame are configured to overlap in the vertical direction at the alignment portion in the rotation axis direction of the exit-side paper guide member. It is possible to prevent the vapor generated in the apparatus from going out of the apparatus and to prevent dew condensation in other units and apparatuses.
[0041]
According to the third aspect of the present invention, since the upper frame has the vertical wall positioned so as to close the inner side of the overlapping portion in the portion where the exit side paper guide member and the upper frame overlap, Thus, it is possible to reliably prevent the vapor from leaking out of the fixing device even if the exit side paper guide member or the upper frame is warped by the fixing heat.
[0042]
According to the fourth aspect of the present invention, the fixing roller, the pressure roller that is in pressure contact with the fixing roller, the separation member that separates the sheet from the fixing roller, and the separation member facing the separation member on the exit side in the sheet conveyance direction. In an image forming apparatus including a fixing device having an exit-side paper guide member provided , the exit-side paper guide member is provided to be rotatable in the paper transport direction, and a paper transport guide member is provided downstream of the exit of the fixing device. The paper conveyance guide member and the outlet side paper guide member each have a comb-shaped guide portion, and the outlet side paper guide member rotates to a predetermined position without opening the paper conveyance guide member. Since it is configured to be possible, when the bellows-like jam occurs in the fixing device, the exit-side paper guide member rotates regardless of the open / close state of the paper transport guide member. Position can be obtained, it is possible to form the escape of jammed paper.
[0043]
According to the fifth aspect of the present invention, the sheet conveying path is formed substantially vertically, the fixing device is arranged at the upper part of the image forming apparatus, and the outlet side paper guide member is located at the upper part of the fixing apparatus. Therefore, the visibility and processability of jammed paper can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic front view of a copying machine as an image forming apparatus according to an embodiment of the present invention.
2 is a schematic front view of the vicinity of a substantially vertical conveyance path of the copying machine shown in FIG. 1;
FIG. 3 is a schematic front view showing a state where a right cover and a paper transport guide member of the copying machine are opened.
FIG. 4 is an exploded perspective view of the fixing device.
FIG. 5 is an enlarged perspective view of a main part of an upper frame and an exit side paper guide member.
FIG. 6 is a schematic front cross-sectional view of the fixing device, and shows a state in which an exit side paper guide member is in a predetermined position.
FIG. 7 is a schematic front sectional view of the fixing device, and shows a state in which an exit side paper guide member is in an open position.
FIG. 8 is a schematic front cross-sectional view of the fixing device, and is a diagram for explaining torque by an urging means of an exit side paper guide member.
FIGS. 9A and 9B are diagrams illustrating a relationship between an exit-side sheet guide member of the fixing device and a sheet conveyance guide member positioned downstream of the fixing device, in which FIG. 9A is a schematic front view, and FIG. 9B is a schematic side view.
FIG. 10 is a schematic front cross-sectional view of the fixing device, and shows a displacement state of the exit side paper guide member by paper when a jam occurs.
[Explanation of symbols]
22 fixing device 42 fixing roller 44 pressure roller 46 fixing separation claw 74 as separation member outlet side paper guide member 74a rotating shaft 74c rib 74d guide surface 84 upper frame 84b vertical wall 86 lower frame 88 torsion coil spring G as urging means Normal line S fulcrum

Claims (5)

A fixing roller; a pressure roller that is in pressure contact with the fixing roller; a separation member that separates the sheet from the fixing roller; and an exit-side sheet guide member that is provided facing the separation member on the exit side in the sheet conveyance direction. In an image forming apparatus provided with a fixing device,
The outlet side paper guide member is provided so as to be rotatable in the paper conveyance direction, and the fixing device is arranged to convey the paper substantially vertically, and the fixing main constituent members such as the fixing roller and the pressure roller. And a lower frame that covers the upper part of the apparatus and that can be attached to and detached from the lower frame, and the upper frame has a support portion for a rotation fulcrum of the outlet side paper guide member. Image forming apparatus. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the exit-side sheet guide member and the upper frame overlap in a vertical direction at a position where the exit-side sheet guide member is aligned in the rotation axis direction . The image forming apparatus according to claim 2 .
The image forming apparatus according to claim 1, wherein the upper frame has a vertical wall positioned so as to close the inner side of the overlapping portion in the portion where the exit side paper guide member and the upper frame overlap . A fixing roller; a pressure roller that is in pressure contact with the fixing roller; a separation member that separates the sheet from the fixing roller; and an exit-side sheet guide member that is provided facing the separation member on the exit side in the sheet conveyance direction. In an image forming apparatus provided with a fixing device ,
The exit side paper guide member is rotatably provided in the paper transport direction, and a paper transport guide member is provided downstream of the fixing device. The paper transport guide member and the exit side paper guide member are each comb-like. An image forming apparatus characterized in that the exit side paper guide member is rotatably provided to a predetermined position without opening the paper transport guide member . The image forming apparatus according to claim 1, 2, 3, or 4.
A sheet feeding unit, an image forming unit, and the fixing device are provided in order from the lower side to the upper side of the apparatus, the sheet conveyance path is formed substantially vertically, and the outlet side sheet guide member is located at the upper part of the apparatus. Image forming apparatus.

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