JP3043444B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic system (a system in which an image formed on a photoreceptor is transferred to paper and recorded) using a laser, such as a printer, a copying machine, and a facsimile.
The present invention relates to an electrophotographic apparatus for performing recording on a sheet by using the method.

[0002]

2. Description of the Related Art Conventionally, in a laser printer, as shown in FIG. 7, for example, an endless and wide photosensitive belt 1 is stretched between a driving roller 2 and driven rollers 3.4, and a casing of a transfer unit 5 is provided. There is a configuration in which a wire 5b is wound across the belt surface 1a of the photoreceptor belt 1 within the belt 5a. Then, the driving roller 2 is rotated to drive the photosensitive belt 1, and a high voltage is applied to the wire 5 b to transfer the image formed on the photosensitive belt 1 to the paper 6.

[0003]

However, in this conventional laser printer, the central portion of each of the rollers 2, 3, 4 is subjected to a strong tension of the photosensitive belt 1 as shown in FIG. It rotates with the side always flexing inward. Then, the photoreceptor belt 1 is rotationally driven in a state where the center side is recessed from both ends in the width direction. As a result, a gap is generated between the center of the belt surface 1a of the photoreceptor belt 1 and the sheet 6, and the transfer of the image on the belt surface 1a to the sheet 6 becomes non-uniform.

SUMMARY OF THE INVENTION It is an object of the present invention to uniformly transfer an image on a photoreceptor belt to a sheet and to prevent a transfer failure such as image unevenness from occurring.

[0005]

According to the present invention, a photoreceptor belt is provided on a plurality of rollers such as a driving roller 11, a driven roller 12, and 13 as shown in the following embodiments. 10, a wire 31 wrapped inside the casing 30 is opposed to the belt surface 10 a of the photoreceptor belt 10, and a high voltage is applied to the wire 31 to print an image formed on the photoreceptor belt 10. In the electrophotographic apparatus for transferring the image to the transfer belt 19, the longitudinal center of the casing 30 on the side facing the photoreceptor belt 10 is formed to be gradually convex in accordance with the belt surface 10a.

According to a second aspect of the present invention, in the electrophotographic apparatus according to the first aspect, for example, as shown in the following embodiments, a sheet
And the transfer guide 30b is formed in the convex shape.

Further, according to a third aspect of the present invention, as shown in the following embodiments, the photosensitive belt 10 is wound around a plurality of rollers such as a driving roller 11 and a driven roller 12. The bias roller 40 is pressed against the photoreceptor belt 10 and the bias roller 4
In an electrophotographic apparatus for transferring an image formed on the photoreceptor belt 10 to a sheet 19 by applying a bias voltage to 0, the center of the bias roller 40 in the length direction is set on the belt surface 10a of the photoreceptor belt 10. It is characterized by being formed in a convex shape together.

[0008]

According to the first aspect of the present invention, the image formed on the photoreceptor belt 10 by driving the photoreceptor belt 10 and applying a high voltage to the wire 31 is printed on the paper 1.
Transfer to No. 9. At the time of the image transfer, the interval between the sheet 19 and the belt surface 10a is made uniform at the longitudinal center of the casing 30 on the side facing the photoreceptor belt 10.

Further, according to the present invention, the transfer guide 30b of the casing 30 during the image transfer described above.
The paper 19 is uniformly brought into close contact with the belt surface 10a and guided in the transport direction.

Further, in the present invention according to claim 3,
The photoreceptor belt 10 is driven, and a bias voltage is applied to the bias roller 40 to transfer the image formed on the photoreceptor belt 10 to the paper 19. At the time of the image transfer, the sheet 19 is brought into close contact with the belt surface 10a at the center in the length direction of the bias roller 40.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic configuration of an internal mechanism of a laser printer according to an embodiment of the present invention. A photoreceptor belt 10 is stretched between a driving roller 11 and driven rollers 12 and 13 in the center of the apparatus main body, not shown. The charger 14 and the optical writer 15 are arranged around the photoreceptor belt 10 in the driving direction (the direction indicated by the arrow in the figure) in this order.
A developing unit 16, a transfer unit 17, and a cleaning unit 18 are arranged. On the right side of the apparatus main body in the figure, a paper feed tray 20 containing paper 19 is detachably attached. And
A paper feed unit 23 having a paper feed roller 21, a paper guide plate 22, and the like is provided in a mounting portion of the paper feed tray 20. On the other hand,
A transport guide 24, a fixing device 25, a paper discharge path 26, and the like are arranged side by side on the opposite side of the transfer unit 17 from the paper supply unit 23. Further, a paper discharge receiver 27 is provided on the upper left side in the figure of the apparatus main body.

Thus, the paper feed roller 21 is driven to feed out the paper 19 from the paper feed tray 20. Then, the paper 19 is guided and conveyed by the paper guide plate 22, and the leading end of the paper 19 abuts against the pair of registration rollers 28 and is stopped. On the other hand, the surface of the photoreceptor belt 10 is sequentially and uniformly charged by the charger 14 while being driven in the direction indicated by the arrow. An image is formed, and then the electrostatic latent image is successively visualized by a toner when passing through the developing unit 16. Then, the paper 19 abutting against the pair of registration rollers 28 is sent out toward the photoreceptor belt 10 at the same timing as the image. Then
The image on the photoreceptor belt 10 is transferred by the transfer device 17 to the sheet 19.
Transfer to After the image is transferred, the toner remaining on the photoreceptor belt 10 is scraped off by the cleaning blade 18a of the cleaning device 18, and the surface of the photoreceptor belt 10 is cleaned on the belt surface 10a.

On the other hand, the paper 19 is sent to a fixing device 25 by a conveyance guide 24, and the transferred image is transferred to the fixing device 25.
To settle. After fixing, the paper 19 is discharged from the apparatus main body through a paper discharge path 26 and is sequentially stacked on a paper discharge receiver 27.

By the way, in the illustrated laser printer,
As shown in FIG. 8, the photoreceptor belt 10 is stretched over the rollers 11, 12, and 13 by the tension thereof, and is stretched around the photoconductor belt 10 in a state where the center side is depressed.

Further, as shown in FIG.
A wire 31 is wound around the casing 30 in the length direction thereof. Then, it is disposed below the driven roller 13 via the photosensitive belt 10. The casing 30 is composed of a case body 30a having a U-shaped cross section opening the upper side in the figure and a sheet 19 formed by bending the case body 30a from the upper edge of the front side (right side in the figure) of the case body 30a in the sheet transport direction. And a transport guide 30b. The transport guide 30b is shown in FIG.
As shown in FIG. 3 and FIG. 3, it is formed in a gradually convex shape from both ends in the longitudinal direction to the center. Then, as shown in FIG. 1, the wire 31 is connected to the belt surface 10a of the photoreceptor belt 10.
And the belt surface 10
The transport guide 30b is arranged close to the transport guide 30a.

In the illustrated laser printer, at the time of image transfer, the drive roller 11 is rotated to drive the photosensitive belt 10 and, at the same time, a high voltage is applied to the wire 31 so that the wire 31 is placed on the belt surface 10a of the photosensitive belt 10. The formed image is transferred to a sheet 19 passing below the belt surface 10a. At this time, the belt surface 10 having a concave center is formed by the transport guide 30b.
The sheet 19 is guided in the transport direction while closely adhering to the sheet a.

In the illustrated embodiment, the center of the conveying guide 30b of the casing 30 in the longitudinal direction is the belt surface 1.
Although the configuration is such that it is gradually convexed in accordance with 0a, for example, as shown in the following illustrated embodiment, the configuration may be such that the center in the length direction of the bias roller is gradually convexed in accordance with the belt surface. That is, in this other embodiment, as shown in FIG. 4, the transfer device 17 includes a bias roller 40, and the bias roller 40 is pressed against the photosensitive belt 10.
A high voltage is applied to the bias roller 40 to apply the photosensitive belt 1
The image formed on the photoreceptor belt 10 is transferred to the sheet 19 passing through the transfer nip portion of both the 0 and the bias roller 40.

As shown in FIGS. 5 and 6, the center of the bias roller 40 in the length direction is gradually convex from both ends, and is adapted to the central concave belt surface 10a of the photosensitive belt 10 shown in FIG. It is formed in a drum shape as a whole.

However, in this embodiment, at the time of image transfer, the belt surface 10a having a concave center at the bias roller 40 is used.
The sheet 19 is brought into close contact with the sheet 19, and the image is transferred to the sheet 19.

[0020]

Therefore, according to the present invention, the longitudinal center of the casing of the transfer unit or the bias roller is formed in a convex shape in accordance with the belt surface of the photosensitive belt stretched in a state where the center is concavely concave. When the image is transferred, the paper is brought into close contact with the belt surface of the photoreceptor belt, and the image thereon is uniformly transferred to the paper, thereby preventing transfer defects such as image unevenness. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an internal mechanism of a laser printer according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a casing of a transfer device in the laser printer.

FIG. 3 is a side view of the casing.

FIG. 4 is a configuration diagram schematically showing an internal mechanism of a laser printer according to another embodiment of the present invention.

FIG. 5 is a perspective view showing a bias roller of a transfer unit in the laser printer.

FIG. 6 is a side view of the bias roller.

FIG. 7 is a configuration diagram schematically showing an internal mechanism of a conventional laser printer.

FIG. 8 is a perspective view showing a state in which a photosensitive belt is stretched in the laser printer.

[Explanation of symbols]

 Reference Signs List 10 photoreceptor belt 10a belt surface 11 drive roller (roller) 12/13 driven roller (roller) 19 paper 30 casing 30b transport guide 31 wire 40 bias roller

Claims (3)

(57) [Claims] 1. A photoreceptor belt is laid over a plurality of rollers, and a wire wrapped in a casing is opposed to the belt surface of the photoreceptor belt, and a high voltage is applied to the wire to apply a high voltage to the photoreceptor belt. An electrophotographic apparatus for transferring a formed image to a sheet, wherein a longitudinal center of the casing on the side facing the photoreceptor belt is formed to be gradually convex in accordance with the belt surface. 2. The electrophotographic apparatus according to claim 1, wherein a transport guide for paper is provided on the casing, and the transport guide is formed in the convex shape. 3. A photoreceptor belt is wound around a plurality of rollers, a bias roller is pressed against the photoreceptor belt, and a bias voltage is applied to the bias roller to transfer an image formed on the photoreceptor belt to a sheet. An electrophotographic apparatus, wherein a center of the bias roller in a length direction is formed to be gradually convex in accordance with a belt surface of the photosensitive belt.