JP3283370B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt-like latent image carrier having flexibility and a transfer roller to which a bias voltage is applied.
The present invention relates to an image forming apparatus of a type in which a transfer material is passed between a transfer member and a toner image formed on a latent image carrier.

[0002]

2. Description of the Related Art The use of the above-mentioned type in an electrophotographic image forming apparatus such as a laser printer is well known. Hereinafter, an example of a conventional image forming apparatus will be described with reference to the drawings. In FIG. 3, a belt-shaped photoreceptor 1, which is a latent image carrier, is driven by a driving means (not shown), driven rollers 9 and 11 rotatably supported, and movably provided. Around the movable support roller 10. When an image is formed, the belt-shaped photoreceptor 1 rotates clockwise in the figure by rotation of the drive roller 8, and a developed image is obtained on the surface under the action of a latent image forming unit and a developing unit (not shown). Further, the belt-shaped photoconductor 1 rotates clockwise in the drawing, and the toner image formed on the belt-shaped photoconductor 1 reaches a pressure contact portion between the belt-shaped photoconductor 1 and the transfer roller 5. At this time, the transfer material is conveyed to the press contact portion by a conveying means (not shown), and the developed image is transferred to the transfer material by the action of the voltage applied to the transfer roller 5. The transferred toner image becomes a fixed image under the action of a fixing unit (not shown).

Here, the belt-shaped photosensitive member 1 needs to be wound with a predetermined tension in order to receive the action of the process means such as latent image formation and development as described above. This is indispensable for the belt-shaped photosensitive member 1 to rotate uniformly at a predetermined speed. Accordingly, in the apparatus shown in FIG. 3, an elastic force is applied in a predetermined direction by a compression spring 13 to a movable support roller 10, which is one of the rollers for supporting the belt-shaped photosensitive member 1. I have.

With respect to the transfer operation by the transfer roller 5, the transfer efficiency is closely related to the nip width based on the deformation of the transfer roller 5 caused by the pressing force against the belt-shaped photosensitive member 1. Therefore, the transfer roller needs to be in pressure contact with the belt-shaped photoreceptor 1 with a constant pressure contact force, and the transfer roller 5 is given an elastic force in a predetermined direction by the compression spring 12. .

In the above-described image forming apparatus,
Since a belt-shaped photoconductor is used as the latent image carrier, various shapes can be formed depending on the arrangement of the support members. Therefore, the arrangement of the various process means is not restricted by the shape of the photoconductor, and the apparatus can be easily miniaturized.

Further, in the above-described image forming apparatus, since a transfer roller is used as a transfer means, the amount of generated ozone is much smaller than when a conventional corona discharge transfer apparatus is used.

[0007]

However, in the conventional image forming apparatus, an elastic force applying member for applying a tension to the belt-shaped photosensitive member 1 and the transfer roller 5 are contacted with the belt-shaped photosensitive member by a constant pressing force. An elastic force imparting member for pressing against the body 1 is required. As a result, there is a problem that the number of parts increases, the cost increases, and the apparatus becomes large.

The present invention has been made in view of the above points, and is an image forming apparatus that is reduced in size and generates less ozone. The number of components is reduced to further reduce the size and cost. It is an object of the present invention to provide an image forming apparatus.

[0009]

In order to achieve the above object, the present invention provides a belt-shaped latent image carrier having flexibility,
A plurality of rollers for supporting the latent image carrier, the plurality of support rollers including one movable support roller movably disposed in a direction for applying tension to the latent image carrier. Latent image forming means for forming a latent image on the latent image carrier, developing means for developing a latent image formed on the latent image carrier, and a developed image formed on the latent image carrier And a transfer roller for electrostatically transferring the image to a transfer material.
The transfer roller is disposed so as to be able to press against the movable support roller via the latent image carrier, and the transfer support roller applies a tension to the image carrier by the pressure contact. Provided is an image forming apparatus which is urged by an elastic force applying member.

[0010]

According to the present invention, the tension of the belt-shaped latent image carrier can be simultaneously obtained by the action of the elastic force applying member for pressing the transfer roller against the belt-shaped latent image carrier, and the number of parts can be reduced. Be reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a main part configuration diagram showing an embodiment of the image forming apparatus of the present invention.

In FIG. 1, a belt-shaped photosensitive member 1, which is a belt-shaped latent image carrier, is wound around a plurality of supporting rollers, and the plurality of supporting rollers are driven by driving means (not shown). It is composed of a driving roller 8, driven rollers 9 and 11 rotatably supported, and a movable supporting roller 10 rotatably disposed so as to be movable in the left-right direction in the figure. During image formation, the belt-shaped photosensitive member 1 rotates clockwise in FIG.

At the time of image formation, the belt-shaped photosensitive member 1 is first charged to a surface potential of -1100 V under the action of the charging device 2,
Next, a latent image is formed by the exposure device 3. The exposure apparatus is constituted by, for example, a laser exposure apparatus. At the time of image formation, digital recording image information sent to the image forming apparatus is received by a line driver circuit (not shown) and amplified by a laser driver circuit (not shown). The digitally recorded image information is a one-bit (recorded / non-recorded) binary signal per pixel, and the laser driver circuit emits a laser diode (not shown) corresponding to the binary signal. Energize. The laser light emitted from the laser diode irradiates the belt-shaped photosensitive member 1 with an image.

Here, the surface potential of the belt-shaped photoreceptor 1 in the portion (image portion) irradiated with light is 0 to -290 V,
Since a developing bias of -800 V is applied to the developing device 4 provided on the downstream side in the rotation direction of the belt-shaped photosensitive member 1, toner charged negatively by the developing device 4 adheres. On the other hand, since the non-image portion is not irradiated with light and the surface potential of the belt-shaped photosensitive member 1 remains at about -1100 V, the negatively charged toner does not adhere even by the developing device 4.

The belt-shaped photosensitive member 1 carrying the developed image developed by the developing device 4 further rotates clockwise in the drawing, and reaches a pressure contact portion between the belt-shaped photosensitive member 1 and the transfer roller 5. At this time, the transfer paper (not shown) is applied to the pressure contact portion between the belt-shaped photosensitive member 1 and the transfer roller 5 such that the leading edge of the transfer paper coincides with the leading edge of the toner image on the belt-shaped photosensitive member 1. And is clamped by the pressure contact portion. The transfer roller 5 has a configuration in which a conductive elastic member is wound around the outer periphery of a metal core, and a voltage having a polarity different from that of the toner on the belt-shaped photosensitive member 1 is applied. As a result, the toner image on the belt-shaped photosensitive member 1 is transferred to a transfer sheet.

Then, the transfer paper on which the toner image has been transferred is separated at the curvature of the belt-shaped photosensitive member 1 and is conveyed to a fixing device (not shown). Here, the toner image on the transfer paper is fused to the transfer paper under the action of heat and pressure to form a fixed image. On the other hand, the belt-shaped photoconductor 1 further rotates clockwise in the figure,
The toner remaining untransferred on the belt-shaped photoreceptor 1 is removed by the action of the cleaning device 6, and then the residual charge remaining on the surface is erased by the action of the static eliminator 7. The image forming operation ends.

Here, in the image forming apparatus of the present invention, the movable support roller 10 has its shaft supported by an elongated hole, and is provided so as to be movable in the horizontal direction in the figure.
The transfer roller 5 is provided so as to be movable in the vertical direction in the figure, and is urged upward by a predetermined force by a compression spring 12 as an elastic force applying member. Accordingly, the driven roller 10 and the transfer roller 5 via the belt-shaped photoreceptor 1
In the pressure contact portion, the driven roller 10 is urged leftward in the drawing by the component of the pressure contact force of the transfer roller 5, and a predetermined tension is applied to the belt-shaped photosensitive member 1. In addition, the transfer roller 5
Is brought into contact with the belt-shaped photoreceptor 1 at a predetermined pressure, so that a predetermined nip is formed.

With the above construction, the transfer roller 5 is pressed against the belt-shaped photosensitive member 1 only by the compression spring 12 for urging the transfer roller 5 with a predetermined force, and the belt-shaped photosensitive member 1 is pressed. Extension is possible, and the mechanism is simplified and the cost can be reduced.

This embodiment has been described with reference to the case where the number of support rollers around which the belt-shaped photosensitive member 1 is wound is four.
As shown in FIG.
Good results can be similarly obtained even with two lines.

[0020]

According to the present invention, there is provided an image forming apparatus which is reduced in size and generates less ozone by using a belt-shaped latent image carrier having flexibility and a transfer roller. Is reduced, it is possible to provide an image forming apparatus that is further reduced in size and cost.

[0021]

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a main part configuration diagram showing a first embodiment of the present invention.

FIG. 3 is a main part configuration diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Belt-like photoreceptor 2 Charging device 3 Exposure device 4 Developing device 5 Transfer roller 6 Cleaning device 7 Static eliminator 8 Driving roller 9,11 Follower roller 10 Movable support roller 12,13 Compression spring

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Claims (1)

(57) [Claims] A belt-shaped latent image carrier having flexibility;
A plurality of rollers for supporting the latent image carrier, the plurality of support rollers including one movable support roller movably disposed in a direction for applying tension to the latent image carrier. Latent image forming means for forming a latent image on the latent image carrier, developing means for developing a latent image formed on the latent image carrier, and a developed image formed on the latent image carrier And a transfer roller for electrostatically transferring the image to a transfer material.
The transfer roller is disposed so as to be able to press against the movable support roller via the latent image carrier, and the transfer support roller applies a tension to the image carrier by the pressure contact. An image forming apparatus, which is urged by an elastic force applying member.