JPH05224571A - Running device for photosensitive belt - Google Patents

Abstract

PURPOSE:To stably maintain the rotating speed by providing a pressure roll to rolate following a driving roll in pressure-contact with it through the photosensitive belt and holding and carrying the photosensitive belt together with the driving roll. CONSTITUTION:The roll in contact with a cleaning blade 12 among the rolls over which the photosensitive belt is hung is made to be a driving roll 13 and the roll immediately upstream of a developing device 8 is made to be a following roll 16. The pressure roll 14 following the driving roll 13 is brought into a pressurized contact with the driving roll 13 by a return spring 15 with the photosensitive belt 1 held in driving roll 13. In this case, since pressurizing force of the photosensitive body against the driving roll 13 as well as tension of the photosensitive body 1 and the pressurizing force of the pressure roll 15 against the driving roll 13 contribute, the tension of the photosensitive belt 1 due to the spring force of the spring 5 can be reduced, and furthermore, because the winding angle of the photosensitive belt 1 to the driving roll 13 can be reduced, the curl generated in the photosensitive belt 1 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoconductor belt running device for an electrophotographic apparatus using a belt-shaped photoconductor.

[0002]

2. Description of the Related Art As a photoconductor for an electrophotographic apparatus such as an electrophotographic copying machine or an electrostatic printer, a belt-shaped photoconductor that is wound around a driving roller and a driven roller and runs by a frictional force with the driving roller. Widely used.

A general structure of a belt-shaped photosensitive member traveling device will be described with reference to FIG. The belt-shaped photosensitive member 1 is stretched over the driving roller 2 and the driven rollers 3 and 4, and the driving roller 2
It is driven to run circumferentially by the frictional force with. The driven roller 4 is a tension roller that applies tension to the belt-shaped photoconductor 1, and is biased by a spring 5 in a direction to push the belt-shaped photoconductor 1 outward from the inside of the belt loop. The peripheral surface of 2 is pressed to generate a frictional force to drive the photoconductor.

On the peripheral surface of the photosensitive belt 1, a charging charger 6, an incident position of the exposure line 7, a developing unit 8, a transfer charger 9, a cleaning unit 10 and a charge eliminating lamp 11 are arranged in this order in the direction of the peripheral movement indicated by the arrow. It is arranged. The electrostatic latent image formed by exposure on the photosensitive belt 1 charged to a predetermined potential by the charging charger 6 is developed by the developing unit 8 to become a toner image, and the transfer charger 9
Is transferred to a transfer sheet under the action of, and is fixed and recorded by a fixing device (not shown). The toner remaining on the photoconductor after the transfer is scraped off by the cleaning blade 12 of the cleaning unit 10, and the potential remaining on the photoconductor 1 is removed by the discharging lamp 11 to prepare for the next image formation.

The photoconductor belt driving force due to the frictional force between the photoconductor belt 1 and the driving roller 2 is applied to the cleaning blade 12 and the sliding load between the bearings of the driven roller 3 and the tension roller 4 and the shaft. , If it is not sufficiently large with respect to the sliding load with the photosensitive belt 1, the photosensitive belt 1
Can not stabilize the speed of. However, dust (toner, paper dust, etc.) in the machine enters the inside of the photoconductor belt over time, and the friction coefficient between the driving roller 2 and the photoconductor belt 1 is reduced, and the driving force is reduced and stabilized. This causes a problem that the rotation speed of the photoconductor belt cannot be maintained.

As means for increasing the driving force, a method of increasing the tension applied to the belt and a method of increasing the winding angle of the belt with respect to the driving roller are known.
The former method increases the sliding load between the shaft of the roller that supports the belt and the bearing, and also increases the required driving force itself, so it is less effective, and the belt is stopped for a certain period of time. If left unattended, the permanent distortion (winding tendency) that occurs in the part of the belt that was wrapped around the roller increases,
In the latter case, on the other hand, the curvature of the photoconductor belt is repeatedly changed, so that the CT layer of the photoconductor is cracked and the image quality is deteriorated. For the purpose of improving this point, preventing the occurrence of cracks in the CT layer of the photoconductor, and improving the life, JP-A-1
Japanese Patent Laid-Open No. 170975 discloses a photoconductor unit in which a photoconductor belt is held in a substantially circular shape by using a guide member or the like to increase a radius of curvature and prevent the curvature from being repeatedly changed. However, the belt becomes complicated, and it is not easy to replace the belt.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the conventional photosensitive belt running device, the present invention is a photosensitive belt capable of stabilizing and maintaining the rotational speed of the photosensitive belt for a long period of time. An object is to provide a traveling device.

[0008]

In order to solve the above-mentioned problems, the photosensitive belt traveling device of the present invention press-follows a driving roller via the photosensitive belt, and nips and conveys the photosensitive belt together with the driving roller. A pressure roller is provided.

[0009]

With the above construction, the pressure roller can press the driving roller against the driving roller to increase the frictional force determined by the product of the friction coefficient and the pressing force without applying a large tension. Thus, the circumferential speed of the belt can be stably maintained without increasing the driving force generated when a large tension is applied to the photoconductor. In this case, the tension applied to the photoconductor belt can be reduced, so that the permanent strain of the photoconductor belt can be suppressed. Further, even if the belt tension is zero, the photoconductor can be nipped and conveyed by the drive roller and the pressure roller, and the belt tension release mechanism for attaching and detaching the photoconductor belt is not required.

By providing the driving roller with a pressure roller for pressing the photoconductor belt, the surface of the photoconductor is charged to a predetermined voltage or the toner image on the photoconductor is transferred to one roller of the roller pair. By providing a means for applying a bias voltage suitable for transferring to the material or removing the residual charge on the photoconductor, the pressure roller can be made to function as a charging charger, a transfer charger, or a charge eliminating device, These chargers and static eliminators can be omitted.

Further, by providing the pressure roller outside the image forming area in the width direction of the photoconductor belt, it is possible to prevent the pressure roller from damaging the image forming area of the photoconductor.

Further, a groove extending in the circumferential direction of the photoconductor belt is provided on one of the pair of rollers for holding the photoconductor belt, and a ridge that fits into the groove is provided on the surface of the photoconductor belt facing the roller. When these are fitted to prevent the meandering of the photoconductor and the displacement in the width direction, the photoconductor belt is sandwiched by a pair of rollers, so it is possible to reliably prevent the ridge from coming off the groove. It

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment in which the present invention is applied to the conventional photosensitive belt running device described in FIG. Therefore, members having the same function are designated by the same reference numeral, and different points will be mainly described.

In this embodiment, the roller which is in contact with the cleaning blade 12 among the rollers around the photosensitive belt 1 is the driving roller 13 and the roller immediately upstream of the developing device 8 is the driven roller 16. A pressure roller 14 driven by the drive roller 13 is pressed against the drive roller 13 by a torsion spring 15 sandwiching the photosensitive belt 1.

Other configurations are the same as those of the conventional device shown in FIG.

The frictional force between the photosensitive belt 1 and the driving roller 13 which gives the driving force for conveying the photosensitive belt 1 is the friction coefficient between them and the driving roller 13 of the photosensitive belt 1.
In this apparatus, the pressing force of the photosensitive belt 1 against the driving roller 13 contributes not only the tension of the photosensitive belt 1 but also the pressing force of the pressing roller 15 against the driving roller 13 in this apparatus. Therefore, the tension of the photoconductor belt due to the spring force of the spring 5 can be made smaller than before, and the wrapping angle of the photoconductor belt around the drive roller can be made smaller. Is reduced, and deterioration of image quality is prevented.

According to the experiment, in the case of the above structure, the tension applied to the photosensitive belt 1 by the spring 5 is 80.
It can be set to gf / cm or less.

Further, as in the embodiment shown in FIG. 2, the tension of the photosensitive belt 1 can be made zero by eliminating the spring 15 for applying the tension to the photosensitive belt 1. In that case, the three rollers 4, 1 around which the photosensitive belt 1 is wound.
The axial positions of 3 and 16 can be fixed, and if the circumferential length of the belt is made slightly longer than the sum of the tangent line connecting the outer circumferences of the rollers and the circular arc, the belt tension releasing member becomes unnecessary. In this case, since the tension for obtaining the frictional force is not applied to the photoconductor belt 1, the life is extended, and the spring 5 is unnecessary, and the roller 4 is not required to be moved, so that the structure is simplified.

In the embodiment shown in FIG. 3, similarly to FIG. 9, the roller 2 immediately upstream of the developing device 8 is a driving roller, and the roller 3 in contact with the cleaning blade 12 is a driven roller. The driving roller 2 is pressed against the driving roller 2 by the torsion spring 15 of the pressure roller 19 via the photosensitive belt 1. Further, in the apparatus of this embodiment, the charging charger 6 is not provided, and instead, when the surface of the photosensitive belt 1 is provided on the pressure roller 19 with the charging charger, the same voltage as the potential charged by the charging charger is obtained. A bias power source 20 for applying a bias voltage for charging is connected. Further, the writing position by the exposure light beam 7 is located on the downstream side of the pressure roller 19. Other configurations are the same as those in FIG.

Therefore, the tension of the photosensitive belt 1 can be reduced or reduced to zero as in the above-mentioned embodiment,
In addition, the bias power source 20 causes the pressure roller 19 to function as a bias roller, and functions as a charging charger.

In the other embodiment shown in FIG. 4, the roller 13 contacting the cleaning blade 12 is the same as the embodiment shown in FIG.
Is a driving roller, and the roller 16 in front of the developing device 8 is a driven roller. The tension roller 4 for applying a tension to the belt 1 by the spring 5 is provided on the pulley and the driving roller 13 provided coaxially therewith. It is rotated at a peripheral speed equal to that of the driving roller 13 by a transmission belt stretched between the pulley and the pulley and acts as a driving roller. In this embodiment, the transfer charger 9 facing the roller 4 is not provided, and the roller 4 is in pressure contact with the pressure roller 22 urged by the spring 15 ′ via the photosensitive belt 1. A bias power source 21 for applying a bias voltage for transferring the toner image on the photosensitive belt 1 to a transfer material is connected to the pressure roller 22.

Therefore, the photosensitive belt 1 includes the roller 4 acting as a driving roller and the pressure roller 2 in pressure contact with the roller 4.
The pressure roller 22 acts as a transfer charger, and is fed between the rollers 4 and 22 by the registration roller pair 25. The toner image on the photosensitive belt 1 can be transferred while the transfer material is held and conveyed.

In yet another embodiment shown in FIG. 5, instead of eliminating the static elimination lamp 11 of the embodiment described in FIG.
A bias power source 2 in which a bias voltage suitable for removing the residual charge on the photoconductor belt 1 is applied to the pressure roller 14 that is in pressure contact with the driving roller 13 via the photoconductor belt 1 is a DC voltage.
3 is applied.

Therefore, the photosensitive belt 1 is nipped and conveyed by the driving roller 13 and the pressure roller 14, so that the tension of the photosensitive belt can be reduced and the pressure roller 1 can be used.
Since No. 4 also functions as a static elimination roller, the static elimination lamp can be omitted, which is useful for cost reduction.

The pressure roller 14 that is in pressure contact with the driving roller 13 via the photosensitive belt 1 in the embodiment shown in FIGS. 1 and 2 is shown by hatching in the width direction of the photosensitive belt 1 as shown in FIG. By providing it outside the image forming area, it is possible to prevent the image forming area of the photosensitive belt 1 from being damaged by the pressure roller.

By the way, as a means for preventing the meandering and the widthwise deviation of the photosensitive belt wound around a plurality of rollers, for example, in JP-A-63-75779, grooves are provided at the side ends of the rollers in the circumferential direction. There is disclosed a structure in which a ridge is provided at a side end of the belt so as to face the ridge, and these are fitted together.
However, when the tension of the belt is weak, there is a drawback that the ridges are easily removed from the groove. 7 and 8 are diagrams in which this idea is applied to the present invention. An annular groove 1 is provided at the side end of the drive roller 13.
3a is provided. On the other hand, a ridge 28 is provided on the inner surface of the photoconductor belt 1 along the entire circumference thereof. Further, the photoconductor belt 1 is sandwiched between the drive roller 13 and
The pressure roller 14 is in pressure contact with. Therefore, the ridge 28 of the photosensitive belt 1 does not come off from the annular groove 13a of the driving roller 13, and it is possible to reliably prevent the belt-shaped photosensitive body from meandering and lateral deviation.

[0028]

As described above, according to the present invention, the driving force can be secured without increasing the tension of the photoconductor belt, so that the photoconductor belt is less likely to be curled and the conveyance failure is prevented. Can be prevented, which helps improve the life.

Further, a bias voltage is applied to the pressure roller which holds and conveys the photosensitive belt in cooperation with the driving roller, and the pressure roller is used as a bias roller.
Either the transfer charger or the static elimination lamp can be omitted, which contributes to cost reduction. Further, when an annular groove is provided at one side end of the roller that holds the photoconductor belt and a ridge is provided at the side end of the photoconductor belt, the meandering and lateral deviation can be reliably prevented. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a sectional view showing still another embodiment of the present invention.

FIG. 4 is a sectional view showing still another embodiment of the present invention.

FIG. 5 is a sectional view showing still another embodiment of the present invention.

FIG. 6 is a perspective view showing still another embodiment of the present invention.

FIG. 7 is a perspective view showing a meandering / lateral deviation prevention unit combined with the photosensitive belt traveling device according to the present invention.

FIG. 8 is a front view thereof.

FIG. 9 is a cross-sectional view showing the configuration of an example of a conventional photosensitive belt traveling device.

[Explanation of symbols]

 1 Photoreceptor Belt 2, 13 Drive Roller 3, 16 Driven Roller 5 Spring 6 Charging Charger 7 Writing Light 8 Developing Unit 9 Transfer Charger 10 Cleaning Unit 11 Electrification Lamp 14, 19, 22 Pressure Roller 20, 21, 23 Bias Power Supply 28 convex stripes

Claims (6)

[Claims] 1. A photoconductor belt traveling device in which a photoconductor belt wound around a drive roller and a driven roller is circulated by the drive roller. The photoconductor belt traveling device presses the drive roller via the photoconductor belt and follows the drive roller. A photosensitive belt traveling device comprising a pressure roller for holding and conveying the photosensitive belt. 2. A means for applying a bias voltage for charging the surface of the photoconductor to a predetermined voltage is provided on one roller of a roller pair that holds the photoconductor belt.
The photosensitive belt running device described in 1. 3. A means for applying a bias voltage for transferring a toner image formed on a photoconductor onto a transfer material is provided on one roller of a roller pair that holds the photoconductor belt. The photosensitive belt running device described in 1. 4. The photoconductor belt according to claim 1, wherein one of the pair of rollers holding the photoconductor belt is provided with means for applying a bias voltage for removing residual charges on the surface of the photoconductor. Traveling device. 5. The photosensitive belt running device according to claim 1, wherein the pressure roller is provided outside the image forming area in the width direction of the photosensitive belt. 6. A groove extending in the circumferential direction of the photoconductor belt is provided on one roller of a roller pair that holds the photoconductor belt, and a protrusion that fits into the groove is formed on the surface of the photoconductor belt facing the roller. A line is provided, and it is characterized by the above-mentioned.
The photosensitive belt running device described in 1.