JP3680186B2 - Transport guide in image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paper conveyance guide in an electrophotographic image forming apparatus such as a copying machine, a print, and a facsimile machine, and other apparatuses having a paper conveyance mechanism.
[0002]
[Prior art]
In electrophotographic image forming apparatuses such as copying machines and printers, the transfer paper fed from the transfer nip formed by nipping the transfer roller on the outer peripheral surface of the photosensitive drum is guided to the entrance of the fixing unit. An unfixed toner image is fixed on the paper surface by an internal fixing roller. There is an unfixed toner image on the upper surface of the transfer paper fed out from the transfer nip, and in order to prevent the toner image from being disturbed, a fixing unit is conventionally arranged in the lateral direction of the transfer nip. In most cases, however, it is necessary to save space on the equipment, and in recent years, transfer paper that holds unfixed toner images is also transported upward. This requires vertical transport, which saves space. However, when the transfer paper holding the unfixed toner image is conveyed vertically in the vertical direction, the stiffness of the transfer paper cannot be used. The transfer paper may fall over due to its own weight, making it impossible to carry. In order to prevent the transfer paper from collapsing, the paper feeding direction from the transfer nip portion is set to a direction inclined from the vertical direction, and the entrance of the fixing unit is arranged on the extension of the feeding direction. ing. When the angle of the conveyance guide plate is set to be vertical with respect to the paper discharge angle from the transfer nip portion, the space is saved, but the stiffness of the transfer paper is used as described above. It becomes impossible to fall down of paper easily. On the other hand, if the conveyance guide plate is tilted greatly in order to prevent the paper from collapsing, the space is not saved, and the merit of the vertical conveyance is reduced. Further, if a guide member is provided on the unfixed image surface side to prevent the transfer paper from falling during conveyance, the image quality is adversely affected by contact with the guide member. In addition, there is a method of using a suction fan for preventing the above-described collapse during paper conveyance. However, this increases the number of parts and increases the cost.
[0003]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above. The transfer paper fed out from the transfer nip formed by the nip between the photosensitive drum and the transfer roller is directed upward, and the fed transfer paper is guided. It is an object of the present invention to provide a conveyance guide in an image forming apparatus that prevents the transfer paper from falling and improves the conveyance performance by setting the shape of the conveyance guide plate to a predetermined value and saving the space of the apparatus.
[0004]
[Means for Solving the Problems]
To achieve the above object, a first aspect of the present invention, a fixing nip portion formed by the fixing roller pair above the transfer nip is arranged, transported to the paper transport path from the transfer nip to the fixing nip portion In an image forming apparatus having a vertical conveyance form in which a guide plate is arranged, the shape of the conveyance guide plate has a multi-face configuration in which the inclination angle changes stepwise from the upstream side to the downstream side. The inclination angle of each surface gradually approaches the vertical direction as it goes downstream, and the most downstream surface of the conveyance guide plate is opposite to the direction in which the paper falls than the guide direction toward the fixing nip. A fixing inlet guide plate that guides the leading end of the paper guided and conveyed by the most downstream surface to the fixing nip is disposed further downstream of the most downstream surface of the conveying guide plate. Have It is characterized in.
The invention according to claim 2 is characterized in that the inclination angle of the first surface located on the upstream side of the conveyance guide plate is set in parallel with the paper discharge angle from the transfer nip portion.
The invention according to claim 3 is characterized in that the inclination angle of the first surface located on the upstream side of the conveyance guide plate is inclined more in the direction of falling of the paper than the paper discharge angle from the transfer nip portion.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
FIG. 1 is a front view showing a schematic configuration of an embodiment corresponding to claim 1. Reference numeral 1 denotes a photosensitive drum, 2 denotes a transfer roller, 3 denotes a conveyance guide plate, 4 denotes a fixing unit, and 5 denotes a fixing inlet guide. is there. The fixing unit 4 includes a heating roller 7 provided with a heater 6 inside, and a pressure roller 8 that presses against the heating roller 7. The heating roller 7 and the pressure roller 8 constitute a fixing roller pair, and the contact portion between both the rollers 7 and 8 forms a fixing nip portion.
The characteristic configuration of this embodiment is that the conveyance guide plate 3 has a multi-surface structure, for example, a three-surface configuration. Specifically, the shape of the conveyance guide plate 3 is inclined from the upstream side toward the downstream side. Is a multi-surface configuration that changes stepwise, and the inclination angle of each surface 3a, 3b, 3c of the transport guide plate is configured to gradually approach the vertical direction as it goes downstream. The configuration of each surface is such that the second surface 3b stands in the vertical direction rather than the first surface 3a. Further, the third surface (the most downstream surface) 3c is configured to stand more vertically than the second surface 3b, and conveys the transfer paper to the inlet of the fixing unit 4 via the fixing inlet guide plate 5. The third surface 3c is configured to be slightly tilted to the opposite side of the vertical direction or the direction in which the transfer paper falls (right direction in the drawing).
As a result, the stiffness of the transfer paper guided by the third surface can be used. The reason why the guide plate 5 is not led directly from the third surface to the unit inlet is due to reasons such as prevention of wrinkles.
The first surface 3a extends in a direction substantially coinciding with the feeding direction from the transfer nip portion.
[0006]
In the above embodiment, the conveyance guide plate 3 has a three-surface structure, but it may have a three-surface structure or a step structure having four or more surfaces.
In short, the effect of this embodiment is that, in an image forming apparatus having a vertical conveying structure, a transfer paper discharge position, such as a nip portion (transfer nip portion) between a photosensitive member and a transfer roller, by providing a multi-sided conveyance guide plate. The transfer paper can be conveyed while using the stiffness of the transfer paper without abruptly changing the transfer paper conveyance angle from the paper, so that the transfer paper can be prevented from falling down and the conveyance surface on the downstream side of the conveyance guide plate can be set up vertically. It is possible to save space.
[0007]
Next, FIG. 2 is a schematic view of an example of a conveyance guide plate corresponding to claim 2. The conveyance guide plate 3 of this embodiment has a two-surface configuration, and the upstream first surface 3a is connected to the transfer nip. It is characteristic that it is configured to be parallel to the transfer paper discharge angle from the section. The second surface 3b is tilted slightly perpendicularly, preferably slightly to the opposite side of the transfer paper tilt direction (right direction). Thus, the transfer paper P can be stably guided to the entrance of the fixing unit while preventing the transfer paper P from falling down.
In short, the effect of this embodiment is to make the conveyance angle of the first surface 3a stand in the vertical direction within a range where stable transfer paper can be conveyed, that is, the discharge angle of the transfer roller and the first of the conveyance guide plate. By making the surfaces parallel, the installation width of the conveyance guide plate can be reduced, so that space can be saved.
[0008]
Next, FIG. 3 is a schematic view of an example of a conveyance guide plate corresponding to claim 3. The conveyance guide plate 3 has a two-surface configuration, and the upstream first surface 3a is formed from the transfer nip portion. It is configured so that the required angle is tilted in the direction in which the transfer paper falls (rightward) than the original discharge angle. For this reason, it is possible to realize a more compact size than the embodiment of FIG.
In short, the effect of this embodiment is that the first surface 3a of the conveyance guide plate is raised from the transfer paper discharge angle of the transfer nip portion (the direction in which the transfer paper stands up), so that the stiffness of the transfer paper with respect to the curled transfer paper or the like Since it can be conveyed while being used, it is possible to improve the conveyance property.
[0009]
【The invention's effect】
As described above, according to the present invention, the conveyance guide plate that guides the transferred transfer paper while making the transfer paper sent out from the transfer nip portion composed of the nip portion between the photosensitive drum and the transfer roller upward. By setting the shape of the sheet to a predetermined value, it is possible to prevent the transfer paper from falling and improve the transportability while saving the space of the device.
That is, according to the first aspect of the present invention, in the image forming apparatus having a vertical conveyance structure, the conveyance guide plate is formed into a multi-sided structure so that the transfer paper is discharged from the nip portion (transfer nip portion) between the photosensitive member and the transfer roller. Transfer paper can be conveyed while using the stiffness of the transfer paper without abruptly changing the transfer paper conveyance angle from the position, so that the transfer paper can be prevented from falling and the conveyance surface on the downstream side of the conveyance guide plate can be set vertically The space can be saved by standing. According to the second aspect of the present invention, the conveyance angle of the first surface is made to stand in the vertical direction within a range where stable transfer paper conveyance can be performed (the discharge angle of the transfer roller and the first surface of the conveyance guide plate are parallel to each other). ), It is possible to reduce the installation width of the conveyance guide plate, thereby saving space.
In the third aspect of the invention, the first surface of the conveyance guide plate is raised from the transfer paper discharge angle of the transfer nip portion (direction in which the transfer paper stands up) while using the stiffness of the transfer paper with respect to the curled transfer paper or the like. Since the conveyance is possible, the fall is prevented and the conveyance property can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of a conveyance guide plate according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a configuration of a conveyance guide plate according to another embodiment of the present invention.
FIG. 3 is a schematic diagram showing the configuration of a conveyance guide plate according to another embodiment of the present invention.
[Explanation of symbols]
1 Photosensitive drum, 2 transfer roller, 3 transport guide plate, 3a, 3b, 3c surface, 4 fixing unit, 5 fixing inlet guide, 6 heater, 7 heating roller, 8 pressure roller,

Claims (3)

Imaging with a fixing nip portion formed by the fixing roller pair above the transfer nip is arranged, the vertical transporting configuration of disposing the sheet guide in the sheet conveying path from the transfer nip to the fixing nip portion In the apparatus, the shape of the conveyance guide plate has a multi-surface configuration in which the inclination angle changes stepwise from the upstream side to the downstream side, and the inclination angle of each surface of the conveyance guide plate gradually increases as it goes downstream. The most downstream surface of the conveyance guide plate is tilted to the opposite side of the paper tilt direction from the guide direction toward the fixing nip,
A fixing inlet guide plate for guiding the leading edge of the paper guided and conveyed by the most downstream surface to the fixing nip is disposed further downstream of the most downstream surface of the conveying guide plate. A conveyance guide in the image forming apparatus.   2. The conveyance guide in an image forming apparatus according to claim 1, wherein an inclination angle of the first surface located on the upstream side of the conveyance guide plate is set in parallel with a paper discharge angle from the transfer nip portion.   The image forming apparatus according to claim 1, wherein an inclination angle of the first surface located on the upstream side of the conveyance guide plate is inclined in a paper tilt direction with respect to a paper discharge angle from the transfer nip portion. Transport guide.

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