JP2005321556A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the belt unit from warping when attaching the belt even if it is not rigid enough in the belt unit frame which attachable to and detachable from an image forming device. <P>SOLUTION: This image forming device has a detachable belt unit. Out of the positioning means of both side plates to attach the belt unit to the main part of the image forming device, at least one of them has three reference positions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as an electronic copying machine, a laser beam printer, an LED printer, and a facsimile, and more particularly, to a belt unit mounting means for conveying a recording paper.

Today, in an image forming apparatus, it is necessary to convey transfer paper at a high speed due to an increase in output speed, and therefore, belt units having high running stability are increasing. Further, due to an increase in demand for full-color output, a tandem type color image forming apparatus that can obtain an output speed comparable to that of a monochrome image has attracted attention, and a belt unit is also used as the image forming unit. The belts of these belt units deteriorate with time. Particularly, a transfer belt or the like that has an influence on image formation deteriorates the image quality due to belt deterioration, and therefore needs to be replaced every time it is used to some extent.
In the conventional belt unit, a frame with high rigidity, such as the use of metal plate front and rear side plates and aluminum extruded stays, was used, and belt replacement was performed by users and service personnel with specialized knowledge.
However, the number of image forming apparatuses that replace the belt unit with the current belt unit is increased so that even a general user can easily replace the belt unit. Therefore, the use of a resin frame is increasing to reduce the weight and cost of the belt unit. Since the frame thickness of the belt unit is reduced due to the size reduction and layout restrictions of the unit, the rigidity of the unit tends to be lowered. When the frame rigidity of the belt unit is weak as described above, the belt unit frame is deformed by bending or the like when attached to the image forming apparatus, and belt running becomes unstable, causing problems such as running of the belt.
In order to solve this problem, there is a proposal to adopt a resin frame in which the front and rear side plates of the belt unit are integrated. However, since the shape is large and complicated, the molding cost is high, and the unit such as the contact / separation mechanism of the transfer belt unit If there are many parts inside, the rigidity will be weak. Further, when the front side plate and the rear side plate of the belt unit are separate parts, it is necessary to increase the thickness of the side plate in order to increase the rigidity of the single part, and thus it is difficult to reduce the size of the unit.

  The present invention has been made in consideration of the above-described circumstances, and even when the belt unit has a low frame rigidity and is suitable for downsizing and weight reduction, the belt unit is not deformed when attached to the image forming apparatus. The purpose is to obtain the means.

In order to solve the above-described problem, the invention described in claim 1 is directed to an image forming apparatus having a removable belt unit, and belt unit mounting side plates for fixing the belt unit to the image forming apparatus main body. Of the positioning means, at least one of the side plates serving as a positioning reference is characterized by at least three recording paper conveying belt units.
According to a second aspect of the present invention, in the recording paper transport according to the first aspect, the positioning means in at least two of the three or more references is a member that holds between both side plates constituting the belt unit. Features a belt unit.
According to a third aspect of the present invention, there is provided a recording paper conveying belt unit in which at least one of the members for holding between both side plates constituting the belt unit according to the second aspect is a roller shaft of a roller constituting the belt unit. It is characterized by.
According to a fourth aspect of the invention, there is provided a recording paper conveying belt unit in which at least one of the roller shafts constituting the belt unit according to the third aspect is a driving roller of the belt unit.
According to a fifth aspect of the present invention, there is provided a recording in which at least one member holding between both side plates constituting the belt unit according to the second aspect also serves as a reference axis of a functional component constituting the function of the belt unit. It features a paper transport belt unit.

  According to the present invention, in an image forming apparatus having a detachable belt unit, among the positioning means of the belt unit mounting side plates for fixing the belt unit to the image forming apparatus main body, at least one of the both side plates. By means of a recording paper conveying belt unit characterized by at least three positioning reference means, even a belt unit having a low rigidity such as a resin frame can be attached with high accuracy to obtain a stable belt running property. Is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

An embodiment according to the present invention is shown in FIG. The belt unit includes a front plate 1 and a rear plate 2 that hold components such as rollers, a driving roller 3 and driven rollers 4 and 5 for running the belt, a tension roller 6 that applies tension to the belt, and tension on the tension roller 6. A spring 8 provided on the shaft portion of the tension roller, a holder 9 that holds and slides the tension roller, and a shaft end portion of the drive roller 3 that provides rotation of the drive motor to the drive roller 3. A coupling 7 is used. These rollers 3, 4, 5, 6 are supported between the front and rear side plates 1, 2. Three reference pins 10 (positioning means) are provided on the outer side surface of the rear side plate 2, and the same reference pins (positioning means) are provided on the outer side surface of the front side plate side 1. At the time of mounting to the image forming apparatus, the reference pin 10 is mounted in a hole (positioning means) provided on the image forming apparatus side so that the unit is positioned at the mounting portion on the image forming apparatus side.
In the embodiment, the shape of the positioning portion is a pin, but there are other methods such as a pin on the image forming apparatus main body side and a hole shape on the belt unit side, or a lower surface of the unit. In addition, the shape, number, position, and the like of the positioning portion may be different between the rear side plate and the front side plate. By this means, even a belt unit having a low rigidity such as a resin frame can obtain a stable belt running property when attached to the main body.

Next, Example 2 is shown in FIG. In the belt unit, both end portions of the reference shafts 11 and 12 are held by the front and rear side plates 1 and 2, and the end portions 11a and 12a of the reference shaft protrude from the both side plates. At the time of attachment to the image forming apparatus, positioning is performed by holding the end portions 11a and 12a of the reference shaft and the reference pin 10 of the side plate through holes provided on the apparatus main body side. That is, the reference shafts 11 and 12 and their end portions 11a and 12a constitute positioning means.
In the present embodiment, both ends of the reference shaft are held, but it is also possible to hold the reference shaft only on one side and hold the side plate on the opposite side. By this means, distortion and misalignment between the front and rear side plates of the belt unit when attached to the image forming apparatus can be reduced.

Next, Example 3 is shown in FIG. In the belt unit, the end portions 4a and 5a of the driven rollers 4 and 5 protrude from the front and rear side plates 1 and 2, and when attached to the image forming apparatus, the end portions 11a and 12a of the driven rollers and the reference pins of the side plates It is positioned by holding 10. In the embodiment, the roller shaft is held, but there is also means for holding the roller shaft only on one side and holding the side plate on the opposite side. In addition, when holding the rotating shaft, in addition to holding the shaft itself, there may be a case where a bearing that is attached to the shaft or a portion that supports the shaft of the side plate is held.
That is, the driven rollers 4 and 5 and their end portions 4a and 5a constitute positioning means.
By this positioning means, the accuracy of the roller position at the time of attachment to the image forming apparatus is increased, so that the belt travelability is stabilized, and parts such as a reference shaft are not required, so that weight reduction and cost reduction can be achieved.

  Next, Example 4 is shown in FIG. At the time of attachment to the image forming apparatus, the coupling (positioning means) 7 of the driving roller 3, the driven roller end (positioning means) 5a, and the reference pin (positioning means) 10 are held by the support portion (positioning means) on the apparatus main body side. It is positioned by doing. In the embodiment, the coupling of the driving roller is held. However, the driving roller shaft, a bearing attached to the driving roller shaft, and a portion of the side plate that supports the driving roller shaft may be held. The positioning means described above increases the positional accuracy of the drive roller, so that more stable belt travelability can be obtained.

Next, Example 5 is shown in FIGS. The embodiment is a transfer belt unit, and the transfer belt 12 is stretched endlessly by a driving roller 3, driven rollers 4, 5 and a tension roller 6, and the driving roller 3, driven rollers 4, 5, and tension roller 6 are run. Is held by the front and rear side plates 1 and 2 via bearings or the like. Inside the unit, there are transfer rollers 13 to 16 that come into contact with the photosensitive member. The driven roller 5 and the transfer rollers 14 to 16 are held by a bracket 17, and the bracket 17 rotates about a shaft 18 to rotate as shown in FIG. Thus, in the state of rotating downward, it is separated from the photosensitive member positioned below. At this time, the shaft (positioning means) 18 supported by the both side plates protrudes outside the both side plates, and serves as a support member for positioning the belt unit when attached to the support portion (positioning means) of the image forming apparatus. Also has a role.
That is, in this embodiment, at least one of the members that hold between both side plates constituting the belt unit also serves as a reference axis for the functional component that constitutes the function of the belt unit. With such a configuration, the functional parts in the belt unit are directly positioned on the image forming apparatus main body, so that the positional accuracy with respect to the main body parts can be increased.

It is a perspective view which shows the structure of the belt unit of this invention. It is a perspective view which shows the other structure of the belt unit of this invention. It is a perspective view of the example of roller axis utilization of the belt unit of the present invention. It is a perspective view of the example of utilization of the drive roller of the belt unit of the present invention. It is a perspective view of the example of utilization of the functional component of the belt unit of the present invention. It is a perspective view of the example of utilization of the functional component of the belt unit of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Front side plate, 2 Rear side plate, 3 Driving roller, 4, 5 Driven roller, 5a End of driven roller, 6 Tension roller, 7 Coupling, 8 Spring, 9 Holder, 10 Reference pin, 11, 12 Reference shaft, 11a, 12a Reference shaft end, 13 driven roller, 14, 15, 16 transfer roller, 17 bracket, 18 shaft

Claims (5)

  In the image forming apparatus having a detachable belt unit, among the positioning means for both side plates for attaching the belt unit for fixing the belt unit to the image forming apparatus main body, means serving as a positioning reference for at least one of the both side plates Is a belt unit for conveying recording paper, characterized in that there are at least three locations.   2. The belt unit for conveying recording paper according to claim 1, wherein at least two positioning means among the three or more references are members that hold between both side plates constituting the belt unit.   A belt unit for conveying recording paper, wherein at least one of the members that hold between both side plates constituting the belt unit according to claim 2 is a roller shaft of a roller constituting the belt unit.   4. A recording paper conveying belt unit, wherein at least one of the roller shafts constituting the belt unit according to claim 3 is a driving roller of the belt unit.   A belt unit for conveying a recording paper, wherein at least one member that holds between both side plates constituting the belt unit according to claim 2 also serves as a reference axis of a functional component constituting the function of the belt unit.

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