JP2010262231A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deflection of a pivotally supporting pin of a transmission gear, and to stabilize transmission of rotation between the transmission gear and a heating roller gear. <P>SOLUTION: An image forming apparatus includes: an apparatus body; a fixing device (fixing unit 80) having a heating roller 81, and made attachable/detachable from one side of the apparatus body; the heating roller gear 83 provided in the fixing device, and coupled with the heating roller 81; the transmission gear (idle gear 110) meshed with the heating roller gear 83 on an inner side in the attaching direction of the fixing unit; a driving source (driving gear 130) giving rotational driving force to the transmission gear; the pivotally supporting pin 120 supporting the transmission gear on a panel of the apparatus body, and having a base end fixed to the panel; and a pin supporting part 92 provided in the apparatus body, and abutting on the tip part of the pivotally supporting pin 120 on the inner side in the attaching direction of the fixing device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a support structure for a gear shaft in an electrophotographic image forming apparatus.

  An electrophotographic image forming apparatus is provided with a fixing device for thermally fixing a toner image formed on a sheet. The fixing device is provided with a heating roller and a pressure roller for sandwiching the paper between the heating roller to apply heat to the paper while transporting the paper, and gears for providing driving force to these are also provided. .

  When the fixing device is configured to be detachable from the apparatus main body of the image forming apparatus, the gear for meshing with the gear of the fixing apparatus and transmitting the driving force is supported by the image forming apparatus main body. For example, as disclosed in Patent Document 1, the intermediate gear that transmits the driving force is cantilevered with respect to the side panel. The gear shaft of the intermediate gear may have to be relatively long for the sake of layout as shown in the document. For this reason, in the image forming apparatus of Patent Document 1, the tip of the gear shaft is in contact with the fixing device so that the position of the gear shaft is regulated by the fixing device so that the gear shaft does not bend excessively.

JP 2008-046549 A

  However, when rotation is transmitted from the intermediate gear to the gear of the fixing device due to the meshing between the gear of the fixing device and the intermediate gear, a force is generated to cause the two gears to separate from each other. Due to this force, the support shaft of the intermediate gear is bent in a direction away from the fixing device. Therefore, the configuration of Patent Document 1 cannot prevent this bending, and it is difficult to ensure stable rotation transmission of the gears. is there.

  SUMMARY OF THE INVENTION An object of the present invention is to realize a stable rotation of a gear that gives a driving force to a fixing device.

  To achieve the above object, the present invention provides an apparatus main body, a fixing device having a heating roller and detachable from one side of the apparatus main body, and a heating unit provided in the fixing device and connected to the heating roller. A roller gear, a transmission gear meshing with the heating roller gear on the back side in the mounting direction of the fixing device, a drive source for applying a rotational driving force to the transmission gear, and supporting the transmission gear on the panel of the apparatus main body, A shaft support pin whose base end portion is fixed to the panel; and a pin support portion provided in the apparatus main body and abutting with a distal end portion of the shaft support pin on the back side in the mounting direction of the fixing device. Features.

  According to such a configuration, when the transmission gear that meshes with the heating roller gear is rotated by the drive source on the back side in the mounting direction of the fixing device, the rotation is transmitted from the transmission gear to the heating roller gear. At this time, force is applied to the transmission gear and the heating roller gear so as to be separated from each other. However, if the tip of the shaft support pin is bent, it contacts the pin support portion on the back side in the mounting direction of the fixing device. Deflection of is minimized. Therefore, stable rotation can be transmitted between the transmission gear and the heating roller gear.

  According to the image forming apparatus of the present invention, the bending of the shaft support pin of the transmission gear is suppressed, and the rotation transmission between the transmission gear and the heating roller gear can be stabilized.

1 is a side sectional view of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view of a fixing device, a paper discharge device, and gears in FIG. 1. It is XX sectional drawing of FIG. (A) is a figure explaining the assembly | attachment of a paper discharge apparatus, (b) is a figure explaining the assembly | attachment of a fixing device. (A) is a figure explaining the effect | action at the time of operation | movement of gears, (b) is an enlarged view of the pivot pin of (a).

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the direction will be described with reference to the user when using the color printer. That is, in FIG. 1, the right side toward the paper surface is “front side”, the left side toward the paper surface is “rear side”, the back side toward the paper surface is “right side”, and the front side toward the paper surface is “left side”. To do. In addition, the vertical direction toward the page is defined as the “vertical direction”.

  As shown in FIG. 1, a color printer 1 as an example of an image forming apparatus includes a paper feeding unit 20 that supplies paper P and an image forming unit 30 that forms an image on the supplied paper P in the apparatus main body 2. And a paper discharge unit 90 for discharging the paper P on which the image is formed.

  An opening 2 </ b> A is formed in the upper part of the apparatus main body 2. The opening 2A is opened and closed by an upper cover 3 that is rotatably supported by the apparatus main body 2. The upper surface of the upper cover 3 is a paper discharge tray 4 that accumulates the paper P discharged from the apparatus main body 2, and a plurality of LED attachment members 5 that hold the LED units 40 are provided on the lower surface.

  The paper feeding unit 20 is provided in the lower part of the apparatus main body 2, and a paper feeding tray 21 that is detachably attached to the apparatus main body 2, and a paper supply mechanism that conveys the paper P from the paper feeding tray 21 to the image forming unit 30. 22 is provided. In the paper feed unit 20, the paper P in the paper feed tray 21 is separated one by one and is sent upward, is turned backward through the transport path 28, and is supplied to the image forming unit 30.

  The image forming unit 30 mainly includes four LED units 40, four process cartridges 50, a transfer unit 70, and a fixing unit 80 as an example of a fixing device.

  The LED unit 40 is swingably connected to the LED mounting member 5, and is appropriately positioned and supported by a positioning member provided in the apparatus main body 2.

  The process cartridge 50 is arranged side by side in the front-rear direction between the upper cover 3 and the paper feed unit 20, and a photosensitive drum 53 on which an electrostatic latent image is formed, a known charger that is not shown by reference numerals, A developing roller and a toner storage chamber are provided. Four photosensitive drums 53 are provided in the front-rear direction along the paper P conveyance path.

  The transfer unit 70 is provided between the paper feeding unit 20 and each process cartridge 50 and mainly includes a drive roller 71, a driven roller 72, a conveyance belt 73, and a transfer roller 74.

  The driving roller 71 and the driven roller 72 are arranged in parallel with a space in the front-rear direction, and a conveyance belt 73 formed of an endless belt is stretched between them. The outer surface of the conveyor belt 73 is in contact with each photosensitive drum 53. In addition, four transfer rollers 74 that sandwich the conveyance belt 73 between the photosensitive drums 53 are arranged inside the conveyance belt 73 in correspondence with the respective photosensitive drums 53. A transfer bias is applied to the transfer roller 74 during transfer.

  The fixing unit 80 is disposed on the rear side of each process cartridge 50 and the transfer unit 70, and includes a heating roller 81 and a pressure roller 82 that is disposed to face the heating roller 81 and presses the heating roller 81. The fixing unit 80 is detachable from an opening 2 </ b> C formed by opening a rear cover 2 </ b> B provided on the rear side surface of the apparatus main body 2.

  In the image forming unit 30 configured as described above, first, the surface of each photosensitive drum 53 is uniformly charged by a charger and then exposed by each LED unit 40. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image based on the image data is formed on each photosensitive drum 53. Thereafter, toner is supplied to the electrostatic latent image from the developing roller, so that the toner image is carried on the photosensitive drum 53.

  Next, the paper P supplied onto the conveyance belt 73 passes between each photosensitive drum 53 and each transfer roller 74 disposed inside the conveyance belt 73, thereby forming on each photosensitive drum 53. The toner image thus transferred is transferred onto the paper P. Then, as the paper P passes between the heating roller 81 and the pressure roller 82, the toner image transferred onto the paper P is thermally fixed.

  The paper discharge unit 90 includes a paper discharge device 91 provided in the apparatus main body 2 above the fixing unit 80. The paper P on which the toner image has been transferred and heat-fixed is conveyed by the paper discharge device 91, discharged outside the apparatus main body 2, and accumulated in the paper discharge tray 4.

  As shown in FIGS. 2 and 3, the heating roller 81 of the fixing unit 80 is provided with a heating roller gear 83 coaxially with the heating roller 81. An idle gear 110 as an example of a transmission gear meshes with the heating roller gear 83 on the back side, that is, the front side, in the mounting direction of the fixing unit 80 (the direction from the rear to the front). The idle gear 110 is rotatably supported by a shaft support pin 120. On the front side of the idle gear 110, a drive gear 130 that is an example of a drive source that applies a rotational drive force to the idle gear 110 is engaged. A driving force is input to the driving gear 130 from the motor 140 directly or indirectly.

  The shaft support pin 120 has a base end 121 fixed by caulking to a side panel 2D, which is an example of a panel, provided in the apparatus main body 2. The tooth width of the idle gear 110 is relatively wide due to the meshing relationship between the heating roller gear 83 and the drive gear 130, and there are other layout restrictions, so the shaft support pin 120 is formed to be very long. Yes. Although it is not impossible to support the shaft support pin 120 with a frame that supports both sides of the idle gear 110 in a both-end supported state, in this embodiment, the space required for supporting these gears is reduced to reduce the color. In order to reduce the size of the printer 1, the pivot pin 120 is fixed to one side panel 2D in a cantilever state.

  The shaft support pin 120 is gradually reduced from the base end side in order to minimize the bending deformation and to enable the assembly and positioning of the idle gear 110, so that the large diameter portion 122, the medium diameter portion 123, and the small diameter portion. Part 124. The idle gear 110 is fitted to the medium diameter portion 123 among them. The thrust position of the idle gear 110 is regulated by a step between the large diameter portion 122 and the medium diameter portion 123 and a stopper (not shown).

  As shown in FIG. 2, the paper discharge device 91 is provided with a pin support portion 92 that protrudes downward and extends at the lower end. The rear surface of the pin support portion 92 is a support surface 93 that abuts on the small-diameter portion 124 of the shaft support pin 120 and restricts deformation of the shaft support pin 120. A chamfer 93 </ b> A is formed between the lower end of the support surface 93 and the lower surface 94 of the pin support portion 92.

  As shown in FIG. 3, a support rib 84 that slightly protrudes forward is formed at the left end of the casing of the fixing unit 80. The support rib 84 has a function of contacting the small-diameter portion 124 of the shaft support pin 120 from the front side in the mounting direction of the fixing unit 80, that is, from the rear side, and restricting the bending deformation of the shaft support pin 120. When viewed from the side, the support rib 84 has a V-shape that opens forward as shown in FIG. 4B, and this V-shape is a circular bottom portion that approximately follows the outer diameter of the small-diameter portion 124. 84A and upper and lower guide portions 84B that are connected to the circular bottom portion 84A and are separated from each other as it goes forward. As shown in FIG. 5B, the radius of curvature R2 in the side view of the circular bottom 84A is strictly set to be slightly larger than the radius of curvature R1 of the small diameter portion 124, whereby the small diameter portion 124 is It always comes into contact with the bottom of the circular bottom 84A.

The operational effects of the color printer 1 of the present embodiment configured as described above will be described.
When assembling the idle gear 110, the fixing unit 80, and the paper discharge device 91 to the apparatus main body 2, first, as shown in FIG. 3, the shaft support pins 120 are caulked and fixed to the side panel 2D of the device body 2, and the shaft support pins are fixed. The idle gear 110 is supported by 120. Then, as shown in FIG. 4A, the paper discharge device 91 is lowered from above and assembled to the device main body 2. That is, the pin support portion 92 approaches the shaft support pin 120 along a direction perpendicular to the longitudinal direction of the shaft support pin 120. The support surface 93 of the pin support portion 92 is preferably located at the same position as the front end of the small-diameter portion 124 of the shaft support pin 120 after assembly of the paper discharge device 91. However, in the dimensions before assembly, due to manufacturing errors of each portion The support surface 93 may be located at a position after the front end of the small diameter portion 124. Further, the position of the support surface 93 moves back and forth due to shaking of the operator's hand during assembly. In the color printer 1 of the present embodiment, the paper discharge device 91 is assembled to the apparatus main body 2 by bringing the pin support portion 92 of the paper discharge device 91 close to the shaft support pin 120 along the direction perpendicular to the longitudinal direction of the shaft support pin 120. Therefore, even when the support surface 93 is slightly rearward from the front end of the pivot pin 120, the curved surface of the small diameter portion 124 is supported by the curved surface of the small diameter portion 124. The pin support portion 92 is moved forward by hitting the contact portion 93 and can be assembled in a state where the support surface 93 and the small diameter portion 124 are in contact with each other. Further, since the chamfer 93A is formed at the lower end of the support surface 93, this chamfer 93A also serves as a guide when assembling, and absorbs the positional deviation in the front-rear direction of the support surface 93 due to manufacturing errors and fluctuations in the assembling operation. be able to.

  After the paper discharge device 91 is assembled, the fixing unit 80 is inserted from the rear side of the apparatus main body 2 (see FIG. 4B), and the V-shaped portion of the support rib 84 is aligned with the small diameter portion 124 to fix the fixing unit. 80 is assembled to the apparatus main body 2.

  When the color printer 1 performs a printing operation, when the color printer 1 receives printing data, the paper P is supplied from the paper feeding unit 20 to the image forming unit 30 as shown in FIG. Thus, the toner image corresponding to the data is transferred onto the paper P. The sheet P onto which the toner image has been transferred enters the fixing unit 80 and is sandwiched between the heating roller 81 and the pressure roller 82 to fix the toner image.

  At this time, as shown in FIGS. 2 and 3, the rotation of the drive gear 130 driven to rotate by the motor 140 is transmitted to the idle gear 110, and the rotation of the idle gear 110 is transmitted to the heating roller gear 83 to rotate to the heating roller 81. Driving force is given.

  As shown in FIG. 5A, the engagement of the drive gear 130 and the idle gear 110 causes a force F1 that separates the two from each other, and this force F1 is the fixing unit 80 disposed after the shaft support pin 120. The support rib 84 is received, and the backward bending of the pivot pin 120 is restricted. Further, the engagement of the idle gear 110 and the heating roller gear 83 causes a force F2 that separates the two from each other, and this force F2 is received by the support surface 93 of the pin support portion 92 disposed in front of the shaft support pin 120. Thus, forward deflection of the pivot pin 120 is suppressed.

  As described above, according to the color printer 1 of the present embodiment, when assembling the paper discharge device 91, the support surface 93 is assembled from the top to the bottom, which is the direction perpendicular to the longitudinal direction of the shaft support pin 120. Is positioned after the front end of the small diameter portion 124, the upper half of the small diameter portion 124 and the curved surface portion of the front half serve as a guide and can be easily assembled.

  During the operation of the color printer 1, the force F <b> 1 that causes the idle gear 110 to deflect the shaft support pin 120 received from the drive gear 130 is received by the support rib 84 of the fixing unit 80, and the heating roller gear 83 and the idle gear 110. It is prevented that the inter-axis distance D becomes too close. Further, the force F <b> 2 that the idle gear 110 receives from the heating roller gear 83 to bend the shaft support pin 120 is received by the pin support portion 92 of the paper discharge device 91. Thereby, the shaft support pin 120 is restricted from being bent and deformed forward. Therefore, the bending deformation of the pivot pin 120 is suppressed, and the rotation transmission between the idle gear 110 and the heating roller gear 83 can be stabilized.

  Further, since the circular bottom portion 84A of the support rib 84 has a shape that substantially follows the curved surface of the small diameter portion 124, even if the shaft support pin 120 repeatedly hits the support rib 84 due to the operation of the fixing unit 80, The surface pressure is relatively low, and wear of the support ribs 84 is minimized.

  As shown in FIG. 5 (b), the radius of curvature R2 of the circular bottom 84A of the support rib 84 is larger than the radius of curvature R1 of the small diameter portion 124, so that the small diameter portion 124 always touches the bottom of the circular bottom 84A. For this reason, it becomes easy to manufacture the center distance D between the heating roller gear 83 and the idle gear 110 accurately.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented as described below.

  For example, in the embodiment, the heating roller gear 83 is directly connected to the shaft of the heating roller 81, but the heating roller gear 83 may be connected to the heating roller 81 via one or more gears.

  In the above-described embodiment, only the configuration in which the fixing device can be attached / detached from the rear side of the apparatus main body is illustrated, but the present invention can also be applied to an image forming apparatus that can be attached / detached from the front side or the upper side of the apparatus main body.

  In the embodiment, the idle gear 110 is shown as an example of the transmission gear, and the drive gear 130 is shown as an example of the drive source. However, a mode in which the transmission gear is the drive gear and the drive source is a motor is also adopted. sell.

  Furthermore, in the embodiment, the example in which the base end portion of the pivot support pin 120 is fixed to the side panel 2D by caulking is shown, but the base end portion of the pivot support pin 120 is fixed to the panel by other means such as screwing. May be.

  Further, the portion where the fixing device abuts on the shaft support pin may be a flat surface or a curved surface. Even in the case of a curved surface, the curvature radius may be a surface smaller than the curvature radius of the pivot pin.

  In the above embodiment, only a color printer is exemplified as the image forming apparatus, but the present invention can be similarly applied to a monochrome printer. Further, the present invention can be applied not only to a printer but also to other image forming apparatuses such as a copying machine and a multifunction machine.

DESCRIPTION OF SYMBOLS 1 Color printer 2 Apparatus main body 2B Rear cover 2D Side panel 80 Fixing unit 81 Heating roller 83 Heating roller gear 84 Support rib 84A Circular bottom part 90 Paper discharge part 91 Paper discharge apparatus 92 Pin support part 93 Support surface 110 Idle gear 120 Axis support pin 121 Base End portion 122 Large diameter portion 123 Medium diameter portion 124 Small diameter portion 130 Drive gear 140 Motor

Claims (5)

The device body;
A fixing device having a heating roller and detachable from one side of the device body;
A heating roller gear provided in the fixing device and connected to the heating roller;
A transmission gear meshing with the heating roller gear on the back side in the mounting direction of the fixing device;
A driving source for applying a rotational driving force to the transmission gear;
The transmission gear is supported on the panel of the apparatus main body, and the base pin is fixed to the panel.
An image forming apparatus, comprising: a pin support portion that is provided in the apparatus main body and abuts against a distal end portion of the pivot support pin on a rear side in a mounting direction of the fixing device.   2. The fixing device according to claim 1, wherein the fixing device is configured to be positioned on a front side in a mounting direction of the fixing device with respect to a distal end portion of the shaft supporting pin, and to restrict bending of the shaft supporting pin. Image forming apparatus.   The image forming apparatus according to claim 2, wherein a portion of the fixing device that restricts the shaft support pin has a curved surface shape that follows the shape of the shaft support pin.   The image forming apparatus according to claim 3, wherein a radius of curvature of the curved shape is larger than a radius of curvature of the support pin.   The said pin support part is provided in the components inserted and assembled with respect to the said apparatus main body along the direction perpendicular | vertical to the longitudinal direction of the said axial support pin, The any one of Claims 1-4 characterized by the above-mentioned. 2. The image forming apparatus according to item 1.

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