JP2006225130A - Endless belt drive device and fixing device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent meandering of a belt and to elongate the service life in an endless belt drive device. <P>SOLUTION: A first chassis 1 rotatably supporting a roller 3 is connected to a second chassis 2 supporting a roller 4 swingable around a bolt 61, by superposing a hole 23 formed on an approximately central part of a lateral plate 22 with a long hole 131 of a lateral plate 12, inserting the bolt 61 into the hole 23 and the long hole 131 from the side of the lateral plate 22 to penetrates through the hole 23 and the long hole 131, and screwing a nut 62 to a tip portion of the bolt 61 protruded from the long bolt 131 of the lateral plate 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an endless belt drive device, and more particularly to an endless belt drive device that prevents belt meandering.

  In an image forming apparatus such as a copying machine, a facsimile machine, or a laser printer, a toner image charged on the peripheral surface of a photosensitive member is transferred to a sheet, and then the toner image is heated and pressurized in a fixing unit to be melted and fixed on the sheet. Yes.

  FIG. 8 shows a configuration diagram of a main part of the fixing device. This fixing device is a fixing device using an endless belt (hereinafter simply referred to as “belt”) 5. A belt 5 is stretched between a heating roller 6 having a rod-like halogen heater H provided in the axial direction and a belt roller 7, and the pressure roller 8 is in pressure contact with the belt roller 7 via the belt 5.

  The heating roller 6 is heated to a predetermined temperature by the halogen heater H. Then, heat is transmitted to the belt 5 in contact with the heating roller 6, and the heated belt 5 rotates to reach the nip portion between the belt roller 7 and the pressure roller 8, where the paper P is heated and pressurized. Then, the image of the toner T on the paper P is melted and fixed.

  In such a fixing device, the belt 5 rotates due to friction with the driving belt roller 7, but the mounting position accuracy of the heating roller 6 and the belt roller 7 is not sufficient, and the load distribution on these rollers is uniform. If not, the belt 5 may meander. Such meandering of the belt 5 causes a positional deviation of the toner image at the time of fixing, and causes a large disturbance in the reproduced image.

Therefore, various proposals have been made so far to prevent the meandering of the belt 5. For example, there has been proposed a technique for preventing meandering of a belt by forming convex portions at both ends of the belt and bringing the convex portions into contact with both ends of the roller (for example, Patent Document 1). 2).
JP 2004-109454 A (Claims, FIGS. 3 and 4) JP 2004-109650 A (Claims, FIGS. 2 and 3)

  However, in the proposed technique, a continuous force is applied to both ends of the belt on which the convex portions are formed, so that the convex portions are peeled off from the belt or cracks are generated at both ends of the belt. There was a possibility that the problem of shortening the service life might occur. Such a problem regarding the meandering of the belt is caused not only in the fixing device but also in the photosensitive belt, the transfer belt, and the conveying belt in the image forming apparatus.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an endless belt driving device that can prevent meandering of the belt and extend the life of the belt. .

  Another object of the present invention is to provide a fixing device capable of obtaining an excellent reproduced image without causing a positional shift of the toner image.

  The present inventor has intensively studied whether or not the belt meandering, which has been inevitably generated until now when the rotational speed is increased, can be suppressed without forming any member on the belt, and rotates in a stretched state. The present invention has been made by paying attention to the characteristic of the belt that the belt moves to the side of higher tension. That is, the endless belt driving device of the present invention is an endless belt driving device in which an endless belt is stretched between two or more rotatable rollers, and the other roller can swing with respect to one roller. It is attached.

  Here, from the viewpoint of more effectively preventing the endless belt from meandering, it is preferable that the roller swings about a substantially central portion in the axial direction of the roller. Moreover, it is preferable to provide the urging member which urges | biases the said both rollers in the direction which mutually spaces apart from the both-sides edge part of the said roller.

  According to the present invention, there is provided a fixing device using the endless belt driving device described above as the endless belt driving device.

  In the endless belt driving device of the present invention, since the other roller is swingably attached to one roller, when the endless belt starts meandering, the roller swings in a direction to suppress meandering, and the meandering of the belt is minimized. To the limit. Further, since a new member is not attached to the belt, the life of the belt can be extended.

  Further, when a biasing member for biasing the rollers in the direction of separating the rollers from each other is provided at both side end portions of the rollers, the roller swings around a substantially central portion in the axial direction of the rollers. Further, meandering of the endless belt can be prevented more effectively.

  In the fixing device of the present invention, since the above-described endless belt driving device is used, meandering of the endless belt is suppressed, and an excellent reproduced image can be obtained without causing a positional shift of the toner image.

  Hereinafter, the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

  FIG. 1 is a configuration diagram showing an example of an endless belt driving device according to the present invention. 2 is a cross-sectional view taken along line AA in FIG. The endless belt driving device of FIG. 1 includes a roller 3 and a roller 4, and a belt 5 (broken line in FIG. 1) is stretched between the roller 3 and the roller 4 in a state where tension is applied. The roller 3 and the roller 4 are rotatably attached to different chassis 1 and 2, respectively. The first chassis 1 includes a pair of side plates 11a and 11b that rotatably support the roller 3, and a lateral plate 12 connected between the side plates. A protruding portion 13 extending outward is formed at a substantially central portion of the horizontal plate 12, and a long hole 131 is formed in the central portion of the protruding portion 13 in a direction perpendicular to the axial direction.

  On the other hand, the second chassis 2 that supports the roller 4 is provided with a pair of side plates 21a and 21b that rotatably support the roller 4 and a horizontal plate 22 that is connected between the side plates, as in the first chassis 1. A hole 23 is formed in a substantially central portion of the plate 22. And this hole 23 and the long hole 131 of the horizontal plate 12 are overlapped, and the bolt 61 is inserted from the side of the horizontal plate 22 so as to pass through the hole 23 and the long hole 131, and from the long hole 131 of the horizontal plate 12. A nut 62 is screwed onto the protruding end portion of the bolt 61 to connect the first chassis 1 and the second chassis 2 so as to be swingable around the bolt 61. At this time, since the first chassis 1 and the second chassis 2 are relatively movable within a range in which the bolt 61 can move in the long hole 131, the belt 5 stretched between the roller 3 and the roller 4 is attached to the belt 5. The bolt 61 is moved in the elongated hole 131 so that tension is applied, and a nut 62 is screwed onto the bolt 61 at a place where a predetermined tension is applied, and the first chassis 1 and the second chassis 2 are connected.

  As shown in FIG. 3, in the endless belt driving device having such a configuration, for example, when the belt 5 moves to the right side ((a) → (b) in FIG. 3), the length in the width direction of the belt 5 is the center in the width direction. Since the right side is longer from the position of the bolt 61, the second chassis 2 swings clockwise around the bolt 61. Then, the tension of the belt 5 becomes lower on the right side and higher on the left side. As described above, since the rotating belt 5 has a characteristic of moving to the high tension side, the belt 5 that has moved to the right side starts to move to the left side of high tension this time due to this belt characteristic ( (B) in FIG. Further, when the belt 5 moves to the left side, the second chassis 2 swings counterclockwise around the bolt 61, and when the tension of the belt 5 is low on the left side and high on the right side, the belt characteristic causes the belt 5 to move. 5 moves to the right again ((c) in the figure). The belt 5 stretched between the rollers 3 and 4 continues to rotate while periodically repeating such small meanders. Such meandering of the belt 5 has no effect on actual use since the belt 5 does not move so much as to reach the ends of the rollers 3 and 4.

  FIG. 4 is a block diagram showing another embodiment of the endless belt driving device according to the present invention. The difference between the apparatus shown in FIG. 1 and this apparatus is that a push spring (biasing member) S that urges the chassis 1 and 2 in the direction of separating the chassis 1 and 2 is attached to both ends of the chassis 1 and 2. It is in. That is, the abutting portions 14 and 24 are vertically suspended so as to face both end portions of the horizontal plate 12 and the horizontal plate 22, and the pressing spring S is interposed between the abutting portions 14 and 24. By attaching the push spring S in this manner, when the belt 5 starts to move in the axial direction, the rapid swing of the chassis 2 is suppressed, and thereby the rapid movement of the belt 5 is suppressed. Further, the push springs S attached to both end portions of the chassis 1 and 2 make the tension distribution in the axial direction of the belt 5 more uniform and make it difficult for the belt 5 to meander. Of course, as the urging member, a conventionally known member such as a leaf spring can be used in addition to the push spring, and the attachment position may be the center portion in addition to the both end portions in the axial direction.

  FIG. 5 is a block diagram showing still another example of the endless belt driving device according to the present invention, and FIG. 6 is a cross-sectional view taken along the line BB of FIG. The first chassis 1 includes a pair of side plates 11a and 11b that rotatably support the roller 3, and a bottom plate 15 connected between the side plates. The bottom plate 15 extends outward, and a long hole 151 is formed at the center in the width direction of the tip portion. On the other hand, like the first chassis 1, the second chassis 2 includes a pair of side plates 21a and 21b that rotatably support the roller 4, and a bottom plate 25 connected between the side plates. A hole 23 is formed in the part. And this hole 23 and the long hole 151 of the bottom plate 15 are overlapped, and the bolt 61 is inserted from the bottom plate 25 side so as to penetrate the hole 23 and the long hole 151, and the bolt protruding from the long hole 151 of the bottom plate 15. A nut 62 is screwed onto the tip portion of 61 to connect the first chassis 1 and the second chassis 2 so as to be swingable around a bolt 61. At this time, since the first chassis 1 and the second chassis 2 are relatively movable within a range in which the bolt 61 can move in the long hole 151, the belt 5 stretched between the roller 3 and the roller 4 is attached to the belt 5. The bolt 61 is moved in the elongated hole 151 so that the tension is applied, and the nut 62 is screwed into the bolt 61 at a place where the predetermined tension is applied, so that the first chassis 1 and the second chassis 2 are connected.

  The apparatus of this embodiment is structurally different from the apparatus of FIG. 1 in that the connecting position of the first chassis 1 and the second chassis 2 is substantially the center of the rotating shaft of the roller 4 in FIG. The point is that it is on the lower side. Since the second chassis 2 swings around the bolt 61 positioned below the roller 4 with respect to the first chassis 1, distortion of the chassis 2 due to external force is suppressed, and the chassis 2 swings stably.

  Further, as shown in FIG. 7, a push spring S that urges the chassis 1 and 2 in the direction of separating them may be attached to both ends of the chassis 1 and 2. Similarly to the above, when the belt 5 starts to move in the axial direction, the rapid swing of the chassis 2 is suppressed, and thereby the rapid movement of the belt 5 is suppressed. Further, the push springs S attached to both end portions of the chassis 1 and 2 make the tension distribution in the axial direction of the belt 5 more uniform and make it difficult for the belt 5 to meander.

  The endless belt driving device of the present invention can be used in the fixing device shown in FIG. In this case, the belt to be used is preferably one in which a base is mainly formed from a heat-resistant resin film such as polyimide, and a silicone rubber as an elastic layer is formed thereon, and PTFE, PFA or the like is formed on the silicone rubber. What coated the release layer of this is more preferable.

  The endless belt driving device of the present invention can naturally be used in a device using a photosensitive belt, a paper transport belt, an intermediate transfer belt, in addition to a fixing device.

It is a block diagram which shows an example of the endless belt drive device which concerns on this invention. It is the sectional view on the AA line of FIG. It is explanatory drawing which shows the drive state of the endless belt drive device of FIG. It is another block diagram which shows the endless belt drive device based on this invention. It is another block diagram which shows the endless belt drive device based on this invention. FIG. 6 is a sectional view taken along line B-B in FIG. 5. It is another block diagram which shows the endless belt drive device based on this invention. FIG. 3 is a configuration diagram illustrating an example of a belt-type fixing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st chassis 2 2nd chassis 3 Roller 4 Roller 5 Belt (endless belt)
6 Heating roller 7 Belt roller 8 Pressure roller H Halogen heater S Push spring (biasing member)
11a, 11b Side plate 12 Horizontal plate 13 Projection 14 Extension plate 21a, 21b Side plate 22 Horizontal plate 23 Hole 24 Bottom plate 61 Bolt 62 Nut 131, 151 Long hole

Claims (4)

In an endless belt driving device in which an endless belt is stretched between two or more rotatable rollers,
An endless belt driving device, wherein the other roller is swingably attached to one roller.   The endless belt driving device according to claim 1, wherein the roller swings about a substantially central portion in the axial direction of the roller.   The endless belt driving device according to claim 1 or 2, wherein a biasing member that biases the two rollers in a direction away from each other is provided at both end portions of the roller. In a fixing device using an endless belt driving device,
A fixing device using the endless belt driving device according to claim 1.

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