JP5080752B2 - Tension roller mounting structure - Google Patents

Description

  The present invention relates to a tension roller mounting structure for tensioning a transfer belt of a transfer unit provided in an image forming apparatus such as a copying machine.

  In an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile, a toner image formed on a photosensitive drum as an image carrier is transferred to a recording paper as a transfer material (recording medium) by a transfer device. This is fixed to the recording paper by applying heat and pressure.

  A transfer belt that runs in a predetermined direction is used as a transfer device in this type of image forming apparatus, but this transfer belt may be loosened due to the influence of heat or the like, so it is always urged and slackened in the tension direction. A tension roller is attached to prevent this. An example of an image forming apparatus provided with this type of transfer belt is disclosed in Patent Document 1.

In addition to the tension roller, the unit frame of the transfer unit in which the transfer belt is disposed includes a drive roller for driving the transfer belt, a driven roller provided to face the drive roller, a plurality of transfer rollers, and the like. These rollers are rotatably supported by respective shafts that are passed between a pair of side plates.
JP-A-10-282805

  The transfer unit has a configuration in which a large number of roller shafts are supported by a pair of left and right side plates. Therefore, when assembling, all the rollers must be assembled at the same time, which requires troublesome work. In addition, since the tension roller presses the transfer belt with a coil spring that is a biasing means, there is a case where it is desired to remove only the tension roller for adjustment or repair of this biasing force. There was a problem that it was extremely difficult to attach and detach only the roller.

  The present invention provides a tension roller mounting structure in which a transfer belt tension tension roller can be attached and detached relatively easily in a transfer unit including a transfer belt in consideration of such problems of a conventional image forming apparatus. Objective.

  In order to solve the above problems, the present invention employs the following configuration.

That is, the tension roller mounting structure according to the first aspect of the present invention is a tension roller mounting structure for tensioning a transfer belt provided in an image forming apparatus.
A unit frame for holding the tension roller, a bearing member that rotatably supports the shaft of the tension roller, a coil spring that urges the bearing member in the direction of pressing the transfer belt, and a detachable attachment to the unit frame With a mounting member,
The mounting member has a longitudinal member which is formed integrally on both sides of the bottom plate and the bottom plate for supporting the end portion of the coil spring,
The upper end portion of the vertical member of the attachment member is formed as an inclined surface that opens to the outside,
With the coil spring disposed between the bottom plate of the mounting member and the bearing member, the engagement hole provided in the vertical member is engaged with the protrusion provided in the unit frame body, thereby allowing the It is characterized in that the mounting member while supporting the bearing member mounted on the unit frame.

  According to a second aspect of the present invention, there is provided the tension roller mounting structure according to the first aspect of the present invention, wherein the bearing member is provided with a bar-like leg extending downward, and the coil spring is externally fitted to the leg. is there.

  In addition, according to a third aspect of the present invention, in the above inventions, the bearing member, the coil spring, and the mounting member are made of a conductive material, and a ground wire is connected to a ground terminal provided on the mounting member.

  According to the present invention, the end of the coil spring that urges the bearing member that supports the tension roller to the transfer belt side is supported by the bottom plate of the mounting member, and the engagement holes of the vertical members that are integrally provided on both sides of the mounting member Since the tension roller is supported by engaging with the protrusion provided on the unit frame of the transfer unit, the tension roller can be easily attached and detached by the attaching and detaching operation of the attachment member.

  Hereinafter, an embodiment of an image forming apparatus including a transfer belt tension roller according to the present invention will be specifically described.

  FIG. 1 illustrates a configuration of a copying machine as an example of an image forming apparatus. A document reading unit 60 including an exposure lamp, a lens, a mirror, and the like is provided on the upper portion of the main body 2 of the image forming apparatus 1. Further, at the lower part of the main body 2, two paper feed cassettes 65 and 65 are provided for storing recording paper for forming images and sequentially supplying them.

  In the original reading unit 60, the original is set face down, the back side thereof is held by a pressing plate, and the surface of the original is scanned with light from an exposure lamp, and the reflected light is passed through a lens, mirror, etc. (Not shown). This light is color-separated by a color separation filter, and each color separation component image is supplied as a color image signal (time-series digital electric signal) to the developing device described below.

  The copying machine 1 in the illustrated example is a tandem color copying machine, and has a black image forming unit 3, a yellow image forming unit 4, a cyan image forming unit 5, and a magenta image forming unit in a main body frame 2 as a developing device. 6 is provided. In addition, the image forming apparatus 1 is provided with an intermediate transfer belt 7 that superimposes the images formed by these four sets of image forming units 3, 4, 5, and 6 before transferring them onto recording paper. .

  The basic configuration of the four sets of image forming units 3, 4, 5, and 6 is the same, and this will be described by taking the magenta image forming unit 6 as an example. The magenta image forming unit 6 includes the photosensitive drum 10 and the belt. An electricity 11, a developing device 12, a primary transfer roller 6a, a cleaning unit 140, and the like are provided. As the photoconductor drum 10, for example, a drum using an amorphous silicon photoconductor is used.

  The cyan image forming unit 5, yellow image forming unit 4, and black image forming unit 3 other than the magenta image forming unit 6 are provided with primary transfer rollers 5a, 4a, and 3a, respectively. As shown in FIG. 2, the primary transfer rollers 3a, 4a, 5a, and 6a are disposed inside the intermediate transfer belt 7 that is a transfer belt according to the present invention, and each of the photosensitive rollers is sandwiched between the intermediate transfer belts 7. The body drum 10 is pressed.

  A laser unit (hereinafter referred to as LSU) 15 is provided below the four sets of image forming units 3, 4, 5, 6. The LSU 15 forms an electrostatic latent image by optically scanning the surfaces of the photosensitive drums 10 of the four sets of image forming units 3, 4, 5 and 6 charged by the respective chargers 11. is there.

  A fixing device 9 for fixing the toner image transferred to the recording paper is provided on the downstream side of the intermediate transfer belt 7. As schematically shown in FIG. 1, the fixing device 9 includes a fixing roller 90 and a pressure roller 92, and is rotationally driven at a predetermined speed by a belt 94 that transmits power from a driving motor.

  On the other hand, a transfer roller 8 for transferring the toner image formed on the intermediate transfer belt 7 onto the recording paper P is provided adjacent to the intermediate transfer belt 7. The transfer roller 8 presses a drive roller 13 provided inside the intermediate transfer belt 7 via the intermediate transfer belt 7.

  The surface of the intermediate transfer belt 7 is formed of a material whose main component is rubber. As shown in FIG. 2, the intermediate transfer belt 7 extends in the direction of arrow A toward the primary transfer rollers 6a, 5a, 4a, and 3a. It moves cyclically. Inside the intermediate transfer belt 7, a drive roller 13 is provided on the downstream side of the primary transfer rollers 6a, 5a, 4a, 3a, and a driven roller 14 is provided on the upstream side of the primary transfer roller 6a. ing. Further, a tension roller 16 for tensioning the intermediate transfer belt 7 is provided on the downstream side of the driving roller 13 and the upstream side of the driven roller 14. The tension roller 16 is urged from the inner side with respect to the intermediate transfer belt 7 by a coil spring 40. In FIG. 2, the unit frame 30 is omitted for convenience of explanation.

  Next, the attachment structure of the tension roller 16 will be described. The tension roller 16 is provided in a transfer belt unit including the intermediate transfer belt 7, the primary transfer rollers 6a, 5a, 4a, and 3a, the driving roller 13, the driven roller 14, and the like. Is attached to the unit frame 30. FIG. 3 shows the unit frame 30.

  4 to 5 show the attachment structure of the tension roller 16. In these drawings, the unit frame 30 supports the bearing member 32 that supports the shaft 17 of the tension roller 16 so as to be movable up and down. A bearing support portion 33 having a pair of frames is provided, and a pair of protrusions 34 are formed on the outer surface of the upper and lower intermediate portions of the bearing support portion 33. Guide grooves 33 a for guiding the vertical movement of the bearing member 32 are provided inside the pair of frames of the bearing support portion 33.

  The bearing member 32 is formed of a plate-like member provided with a hole 35 for inserting and supporting the shaft 17 of the tension roller 16, and a lower end portion thereof is provided with a rod-like leg 37 extending downward. A pair of drooping portions 38, 38 that slightly protrude downward are formed on both sides. A coil spring 40 (see FIGS. 2 and 6) is externally fitted to the leg 37 as a biasing means for biasing the tension roller 16 toward the intermediate transfer belt 7 side. The upper end portion of the coil spring 40 is located between the hanging portions 38 and 38.

  On the other hand, an attachment member 42 (see FIGS. 2, 5, and 6) for attaching the bearing member 32 to the bearing support portion 33 of the unit frame 30 is provided. The attachment member 42 is formed by bending a metal material such as a stainless steel plate, and includes a bottom plate 44 in which an upward projection 43 is cut and raised at the center. The projection 43 is for fitting a lower end portion of the coil spring 40 extending downward from the lower end portion of the leg 37 to prevent the displacement of the coil spring 40. In addition, a pair of left and right vertical members 45, 45 that are bent at right angles from the bottom plate 44 and extend upward are integrally formed at both ends of the bottom plate 44. .

  An engaging hole 48 that engages with the protrusion 34 of the unit frame 30 is provided in the upper and lower intermediate portions of the vertical member 45, and an inclined portion 46 that opens outward is formed at the upper end portion. Further, the attachment member 32 is provided with a ground terminal 49 formed by bending the bottom plate 44 upward. The ground terminal 49 is provided with connection holes 49a and 49b.

  When the tension roller 16 is attached to the unit frame 30, first, all the rollers other than the tension roller, that is, the primary transfer rollers 6a, 5a, 4a, 3a, and the driving roller are attached to the unit frame 30 having a pair of side plates. 13. Install the driven roller 14.

  Next, the bearing member 32 is fitted in the guide groove 33a of the unit frame 30, and the intermediate transfer belt 7 is fitted outside the rollers. After that, one end of the coil spring 40 is fitted to the protrusion 43 of the mounting member 42, and the other end is fitted to the leg 37 of the bearing member 32 in this state and attached to the unit frame 30. As a result, the tension roller 16 is pressed against the intermediate transfer belt 7 by the coil spring 40. When the intermediate transfer belt 7 is stretched due to the influence of heat or the like, the coil spring 40 is stretched to tension the intermediate transfer belt 7 so as not to loosen.

  The lower end portion of the coil spring 40 is in contact with the bottom plate 44 of the attachment member 42, and the reaction force that presses the intermediate transfer belt 7 acts downward on the bottom plate 44. The attachment member 42 is made of an elastic metal material. When this reaction force acts on the bottom plate 44, the central portion of the bottom plate 44 is elastically deformed downward. When the central portion of the bottom plate 44 moves downward, an inward force acts on the left and right vertical members 45, 45 formed integrally with the bottom plate 44. For this reason, a force that deepens the engagement between the engagement hole 48 and the unit frame 34 acts, and it is difficult for both to deviate.

  When the attachment member 42 is removed from the unit frame 34, the left and right inclined portions 46, 46 provided at the upper end portion may be widened by hand so that the engagement hole 48 deviates from the protrusion 34. When the engagement between the engagement hole 48 and the projection 34 is released, the attachment member 42 can be pulled down to be easily removed from the unit frame, and the tension roller 16 and the bearing member 32 can also be removed from the unit frame 34. it can.

  The tension roller 16 and the shaft 17 are made of a metal material. The bearing member 32 is formed of a conductive resin material, and is electrically connected to the mounting member 42 via a coil spring 40 made of a metal material. One end of a tension spring 50 constituting an earth wire is engaged with one of the two connection holes 49a and 49b provided in the earth terminal 49. The other end of the tension spring 50 is connected to the side plate 30a of the unit frame 30 that is grounded. The other connection hole 49b is engaged with the end of a tension spring (ground wire) 50 drawn from the ground terminal of another roller, and is connected to the side plate 30a via the attachment member 42. As described above, since the grounding is performed by using the attachment member 42 for the tension roller, the structure is simple.

  The case where an image is formed on the recording paper P by the image forming apparatus 1 will be described. First, the color separation component image from the document reading unit 65 is supplied to the LSU 15 as a color image signal, and the LSU 15 scans according to each color. A latent image is formed on the photosensitive drum 10. This latent image is converted into a toner image of each color separation component by the four sets of image forming units 3, 4, 5, 6. These image forming units 3, 4, 5 and 6 are for attaching toner to a latent image formed on the surface of each photosensitive drum 10 to form toner images of respective color separation components. An appropriate amount of toner is supplied to the surface of the photosensitive drum, and the toner is attached only to the charged portion of the surface of the photosensitive drum 10.

  The image of each color separation component formed on the photosensitive drum 10 is transferred onto the intermediate transfer belt 7 and transferred onto the surface of the recording paper P at a nip portion formed by the intermediate transfer belt 7 and the transfer roller 8. The recording paper P is fed from the paper feed cassette 65 at a predetermined timing, and the toner image on the intermediate transfer belt 7 is transferred while passing through the gap between the intermediate transfer belt 7 and the transfer roller 8.

  After the transfer, the photosensitive drum 10 and the transfer belt 7 are cleaned by a cleaning device. As described above, a full-color image is formed on the surface of the recording paper P. However, when forming a black single-color image, for example, instead of the full-color image as described above, only the black image forming unit 3 is used. Development may be performed.

  The recording paper P to which the image has been transferred is fixed by the fixing device 9. As described above, the fixing device 9 includes the fixing roller 90 and the pressure roller 92, and the fixing roller 90 includes a heater. On the other hand, the pressure roller 92 is urged toward the fixing roller 90 by an urging means (not shown). The pressure roller 92 is driven by the rotation of the fixing roller 90 while pressing against the fixing roller 90 and pressing the fixing roller 90. It is designed to rotate. When the recording paper P carrying the toner image is passed through the nip portion between the fixing roller 90 and the pressure roller 92, the toner melts and adheres firmly to the surface of the recording paper by the heat and pressure of the fixing roller 90. To do.

  In this image forming apparatus 1, the tension roller 16 that tensions the intermediate transfer belt 7 is attached to a predetermined position of the unit frame 30 via the attachment member 42, so that the unit frame to which other rollers are attached, The tension roller 16 can be attached and detached independently. This facilitates maintenance and inspection, and is extremely convenient in practice. Further, since the grounding is performed via the mounting member 42, the grounding structure is simple.

  The tension roller mounting structure according to the present invention enables the tension roller for tensioning the transfer belt to be attached and detached relatively easily in a transfer unit for an image forming apparatus, and is effective for electrophotographic copying machines, printers, facsimiles, and the like. Can be used.

1 is a front view schematically showing an outline of an image forming apparatus. 2 is a front view of an intermediate transfer belt. FIG. It is the perspective view seen from the upper side of the unit frame. It is a perspective view of a tension roller attachment part. It is an exploded view of the principal part. It is a typical sectional view of a tension roller attachment part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body 3 Image forming unit 4 Image forming unit 5 Image forming unit 6 Image forming unit 7 Intermediate transfer belt 8 Transfer roller 9 Fixing device 10 Photosensitive drum 16 Tension roller 30 Unit frame 34 Projection 40 Coil spring (biasing) means)
42 Mounting member 47 Leg 48 Engagement hole 49 Ground terminal 50 Ground wire

Claims (3)

A tension roller mounting structure for tensioning a transfer belt provided in an image forming apparatus,
A unit frame for holding the tension roller, a bearing member that rotatably supports the shaft of the tension roller, a coil spring that urges the bearing member in the direction of pressing the transfer belt, and a detachable attachment to the unit frame With a mounting member,
The attachment member includes a bottom plate that supports an end portion of the coil spring and vertical members that are integrally formed on both sides of the bottom plate,
The upper end portion of the vertical member of the attachment member is formed as an inclined surface that opens to the outside,
With the coil spring disposed between the bottom plate of the mounting member and the bearing member, the engagement hole provided in the vertical member is engaged with the protrusion provided in the unit frame body, thereby allowing the A tension roller mounting structure, wherein the mounting member is mounted on the unit frame in a state where the bearing member is supported.   The tension roller mounting structure according to claim 1, wherein the bearing member is provided with a bar-like leg extending downward, and the coil spring is externally fitted to the leg.   The tension roller mounting structure according to claim 1 or 2, wherein the bearing member, the coil spring, and the mounting member are made of a conductive material, and a ground wire is connected to a ground terminal provided on the mounting member.

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