JPH1191979A - Belt drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably prevent deviation of an endless belt running around a plurality of rollers through simple constitution. SOLUTION: When a development belt 8 is rotated, the development belt 8 is positioned closer to the truncated cone roller 15, and an end part is rotated over the truncated cone roller 15 to rotated the truncated cone roller 15. Through rotation of the truncated cone roller 15, a holding string 16 is wound, and the end part of a belt deviation detecting roller 7 around which the hold string 16 is wound through rotation of the truncated cone roller 15 and the end part of a belt deviation detecting roller 7 is displaced in an opposite direction to a spring 18. The end part of the belt deviation detecting roller 7 is further displaced in an opposite direction to the spring 18, and a development belt 8 is started to approach the opposite side to the truncated cone roller 15 side. An amount of rotation of the development belt 8 over the truncated cone roller 15 is decreased and rotation torque of the truncated cone roller 15 is decreased and the hoising force of the holding string 16 is gradually decreased. The end part of the belt deviation detecting roller 7 is returned in the direction of a spring through the tensile force of the spring 18, and deviation of the development belt 8 is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for an endless belt used in an image forming apparatus such as a copying machine or a printer, and more particularly to a device for preventing the belt from being shifted.

[0002]

2. Description of the Related Art An endless belt which is wound around rollers and used for a developing belt of a copying machine or the like has dimensional errors and mounting errors of each roller, imbalance in belt tension, uneven belt circumference, and the like. And / or if an external force is applied to the belt, they cause the belt to shift. The driving roller connected to the driving motor for driving the endless belt contributes most to the dimensional error and the mounting error of each roller. In order to prevent the deviation of the belt, for example, as shown in FIG. 6, an endless belt conveying device disclosed in Japanese Patent Application Laid-Open No. 4-144850 includes a driving roller 62 connected to a driving motor 61 and a plurality of driven rollers. Endless belts 69, 63, 64, support rollers 65, 66 for ensuring flatness in the sheet conveying area, and a steering roller 67 and an auxiliary roller 68 which are provided between the support roller 66 and the driven roller 64 and whose alignment can be adjusted. Is crossed over. Then, the alignment of the steering roller 67 is changed, and the endless belt 69 is moved in the width direction at a speed corresponding to the amount of change in the alignment to correct the belt deviation.

[0003]

However, the driving roller 62 contributes most to the belt deviation due to the dimensional error and the mounting error of each roller. However, a plurality of rollers are provided between the steering roller 67 for changing the alignment and the driving roller 62. Therefore, the amount of change in the alignment of the steering roller 67 needs to be increased in order to adjust the belt shift. This steering roller 67
The auxiliary roller 68 is provided between the steering roller 67 and the driven roller 64 to minimize the amount of change in the alignment of the belt 69, and the winding angle of the belt 69 around the steering roller 67 is increased. It becomes expensive.

[0004] It is an object of the present invention to improve such disadvantages and to obtain a belt driving device capable of stably preventing deviation of an endless belt stretched over a plurality of rollers with a simple structure. .

[0005]

SUMMARY OF THE INVENTION A belt driving apparatus according to the present invention includes at least four rollers including a driving roller and a plurality of driven rollers, and a belt shift detection provided at a position adjacent to the preceding or succeeding stage of the driving roller. A drive device for an endless belt stretched over rollers, wherein at least one end of the belt shift detection roller is rotatably supported on a rotation shaft of the belt shift detection roller, and the inside on the side of the belt shift detection roller is smaller than the outside. Belt deviation correcting means having a frusto-conical roller formed to have a diameter, a holding cord attached to an end of the frusto-conical roller, and a spring for pulling the circular belt deviation detecting roller in a direction opposite to a holding direction of the holding cord. Is provided.

It is desirable to increase the winding angle of the endless belt around the belt deviation detecting roller.

The endless belt is a developing belt, and the developer is preferably transferred to the latent image carrier between the driven rollers.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A belt driving apparatus according to the present invention includes a driving roller connected to a driving motor, at least two driven rollers, a belt deviation detecting roller provided at a position adjacent to the driving roller, and each roller. And an endless belt stretched over the endless belt. One end of the belt shift detection roller is swingably supported by belt shift correcting means. The belt shift correcting means includes a frusto-conical roller rotatably supported on a rotation shaft of the belt shift detecting roller, and one end fixed to the main body and the other end wound around the end of the frusto-conical roller. And a spring attached to a bearing attached to the rotation shaft of the belt shift detection roller and pulling the belt shift detection roller in a direction opposite to the holding direction of the holding string. The truncated cone roller is formed with a small diameter on the side of the belt shift detection roller, and the small diameter side is equal to or slightly smaller than the outer diameter of the belt shift detection roller.

In the belt deviation correcting means, the belt deviation detecting roller is inclined at a predetermined angle toward the spring in an initial state, and the rotating developing belt rides on the truncated cone roller. In this state, when the driving roller is rotated to rotate the developing belt, the developing belt is biased toward the frustoconical roller side, and the end rides on the frustoconical roller, and a rotational torque acts on the frustoconical roller due to friction with the developing belt. And rotate. Due to the rotation of the truncated cone roller, the holding cord is wound around the truncated cone roller, and the end of the belt shift detection roller is displaced in the direction opposite to the spring. When the end of the belt deviation detecting roller is displaced to some extent, the deviation of the developing belt on the side of the truncated cone roller stops. In this state, when the end of the belt deviation detecting roller is further displaced in the direction opposite to the spring, the developing belt starts to move toward the side opposite to the frustoconical roller, and the amount of the developing belt riding on the frustoconical roller decreases, and the frustoconical roller , The winding torque of the holding cord is gradually reduced, and the end of the belt shift detecting roller is returned in the direction of the spring by the pulling force of the spring.
In this way, the amount of inclination of the belt shift detecting roller is automatically adjusted to prevent the shift of the developing belt.

[0010]

FIG. 1 is a block diagram of one embodiment of the present invention.
As shown in the drawing, an image forming section of the image forming apparatus has a developing device 2 for visualizing an electrostatic latent image formed on the photoconductor 1. The developing device 2 is connected to a drive motor 3, and is provided at a position adjacent to the drive roller 4, two driven rollers 5 and 6, and an outer peripheral surface made of a material having a high friction coefficient such as rubber. A developing belt 8 comprising an endless belt which is wound around a belt deviation detecting roller 7 and each of the rollers 4 to 7 and to which a developing bias potential is applied by driven rollers 5 and 6.
And a liquid storing a high-viscosity liquid developer 9 of 100 to 10,000 mPa · s in which toner as visualized particles is dispersed in a high concentration in a developer solvent made of an insulating liquid such as dimethylpolysiloxane oil. A developer storage unit 10, an application roller 11 that applies a liquid developer 9 to the developing belt 8 to form a liquid developer thin layer, and supplies the application roller 11 with the liquid developer 9 in the liquid developer storage unit 10. And a belt cleaning unit 13. While the developing belt 8 is being rotated by the driving roller 4, a thin layer of liquid developer is formed on the surface by the application roller 11, and the liquid developer is applied to the photoconductor 1 when passing through the developing area between the two driven rollers 5 and 6. By transferring the thin layer, the electrostatic latent image formed on the photoconductor 1 is made a visible image. The liquid developer remaining on the developing belt 8 passing through the developing area is removed by the belt cleaning unit 13 and collected.

As shown in FIG. 2, one end of the belt shift detecting roller 7 is swingably supported by a belt shift correcting means 14. The belt deviation correcting means 14 includes a frusto-conical roller 15 rotatably supported by a rotation shaft of the belt deviation detecting roller 7, one end fixed to the main body, and the other end fixed to the end of the frusto-conical roller 15. It is attached to a holding cord 16 attached so as to be wound and a bearing 17 attached to the rotation shaft of the belt shift detecting roller 7, and pulls the belt shift detecting roller 7 in a direction opposite to the holding direction of the holding string 16. And a spring 18. The inside of the truncated cone roller 15 on the side of the belt shift detection roller 7 is formed to have a smaller diameter than the outside, and the small diameter side is formed to be the same as or slightly smaller than the outer diameter of the belt shift detection roller 7, or the end of the small diameter side is chamfered. It has an R shape. An outer end of the truncated cone roller 15 on the large-diameter side has a winding portion 151 of a holding cord 16 formed of a cylindrical portion.

The belt shift correcting means 14 is pulled by a spring 18 in an initial state, and the amount of the holding string 16 wound around the winding portion 151 of the truncated cone roller 15 is small, and as shown in FIG. The roller 7 is inclined at a fixed angle toward the spring 18, and the rotating developing belt 8 rides on the truncated cone roller 15.

In this state, when the driving roller 4 is rotated by the driving motor 3 to rotate the developing belt 8, the rotating developing belt 8 is biased toward the frustoconical roller 15 side, and the end portion is conical with the frustoconical roller 15. On the surface. When the end of the developing belt 8 rides on the conical surface of the truncated cone roller 15,
The frustoconical roller 15 is rotated by a rotational torque acting due to friction with the developing belt 8. The rotation of the truncated cone roller 15 causes the holding cord 16 to be wound around the winding portion 151, and the end of the belt shift detection roller 7 is displaced in the direction opposite to the spring 18. As the end of the belt deviation detecting roller 7 is displaced, the amount of deviation of the developing belt 8 on the side of the truncated cone roller 15 decreases, and when the end of the belt deviation detecting roller 7 is displaced to some extent, the truncated cone of the developing belt 8 is displaced. The deviation on the roller 15 side stops. In this state, when the end of the belt deviation detecting roller 7 is further displaced in the direction opposite to the spring 18, the developing belt 8 starts to move toward the side opposite to the frustoconical roller 15 side, and the amount of the frustoconical roller 15 riding on the conical surface decreases. . When the amount by which the developing belt 8 rides on the frusto-conical roller 15 decreases, the frictional force of the developing belt 8 on the frusto-conical roller 15 decreases, the rotational torque of the frusto-conical roller 15 decreases, and the winding force of the holding cord 16 gradually decreases. The end of the belt shift detecting roller 7 is returned toward the spring 18 by the pulling force of the spring 18.

In this manner, the deviation of the developing belt 8 can be prevented by automatically adjusting the amount of inclination of the belt deviation detecting roller 7. Further, since the belt deviation detecting roller 7 having the belt deviation correcting means 14 is provided at a position adjacent to the driving roller 4 which contributes to the belt deviation most due to dimensional errors and mounting errors, the belt deviation can be adjusted stably. Further, since the deviation of the developing belt 8 is adjusted outside the developing area between the two driven rollers 5 and 6, the developing belt 8 does not move in the width direction in the developing area between the driven rollers 5 and 6, and the photosensitive member 1 is not moved. And a stable visible image can be formed.

In the above embodiment, the description has been given of the case where the belt deviation detecting roller 7 is provided at the preceding stage of the driving roller 4 in the moving direction of the developing belt 8, but as shown in FIG. It may be provided at a later stage. As shown in FIG. 5, the winding angle θ of the developing belt 8 with respect to the belt deviation detecting roller 7 is, for example, about 60 degrees to 90 degrees.
Degree, the developing belt 8 is
5 can be increased, and the rotational torque of the truncated cone roller 15 can be stably obtained.

Although the above embodiment has been described with reference to the case where the deviation of the developing belt 8 composed of an endless belt is corrected, the deviation of various endless belts such as an intermediate transfer belt can be similarly corrected.

[0017]

As described above, according to the present invention, the amount of inclination of the belt deviation detecting roller is mechanically automatically adjusted by utilizing the deviation of the endless belt, so that the deviation of the endless belt can be reliably prevented. it can.

Further, by providing the belt deviation detecting roller having the belt deviation correcting means at a position adjacent to the driving roller which most contributes to the belt deviation due to a dimensional error or an installation error, the belt deviation can be adjusted stably. At the same time, the amount of correction of the belt shift can be reduced, and the size of the apparatus can be reduced.

Further, since the deviation of the developing belt composed of the endless belt is adjusted outside the developing region between the driven rollers, the developing belt does not move in the width direction in the developing region between the driven rollers, and is stable on the latent image carrier. A visible image can be formed.

Further, by increasing the winding angle of the endless belt with respect to the belt deviation detecting roller,
The endless belt can increase the frictional force acting on the truncated cone roller, and can stably correct the deviation of the belt.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a belt shift correcting unit.

FIG. 3 is a configuration diagram illustrating an initial state of a belt shift correcting unit.

FIG. 4 is a configuration diagram of a second embodiment.

FIG. 5 is a configuration diagram of a third embodiment.

FIG. 6 is a configuration diagram of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 2 developing device 3 drive motor 4 drive roller 5 driven roller 6 driven roller 7 belt deviation detection roller 8 development belt 14 belt deviation correction means 15 frustoconical roller 16 holding string 17 bearing 18 spring

Claims (3)

[Claims] 1. An endless belt driving device which is wound around at least four rollers including a driving roller and a plurality of driven rollers, and a belt deviation detection roller provided at a position adjacent to the front or rear stage of the driving roller. A frusto-conical roller, rotatably supported on at least one end of the belt-deviation detection roller on a rotation shaft of the belt-deviation detection roller, and having an inner side on the belt-deviation detection roller side formed to have a smaller diameter than an outer side; And a spring for pulling a belt shift detection roller in a direction opposite to a holding direction of the holding string. 2. The belt driving device according to claim 1, wherein the winding angle of the endless belt around the belt deviation detecting roller is increased. 3. The belt driving device according to claim 1, wherein the endless belt is a developing belt, and the developer is transferred between the driven rollers to the latent image carrier.