JPH05119602A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To provide an electrophotographic device capable of always and properly forming an image without abrading a developing roller and the substrate of a photosensitive body, and changing a gap between the developing roller and the photosensitive body in the lapse of time. CONSTITUTION:Both end parts 21a of a photosensitive drum 21 is covered with polyacetal. A gap roller 110 is made of the polyacetal. Therefore, the hardness of both end parts 21a of the photosensitive drum 21 is the same as that of the gap roller 110.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus such as a copying machine.

[0002]

2. Description of the Related Art In a full-color copying machine or the like, developers of yellow, magenta, and cyan colors are supplied to an electrostatic latent image formed on a photosensitive member for development. 7 and 8
In FIGS. 1A and 1B, reference numeral 1 indicates a photoconductor drum mounted in a full-color copying machine. The photoconductor drum 1 rotates clockwise and an electrostatic latent image is formed by a device (not shown). The base of the photosensitive drum 1 is made of metal such as aluminum.

Reference numeral 9 indicates a developing roller of a developing device mounted on a full-color copying machine, and the developing roller 9 is a rotary shaft 1
It is fixed at 1. The gap rollers 10 are fixed to both ends of the rotary shaft 11. The diameter of the gap roller 10 is larger than the diameter of the developing roller 9 by a predetermined dimension. The gap roller 10 is made of resin.
Although not shown in the figure, this full-color copying machine is provided with a developing device that supplies the developer of each color of yellow, magenta, cyan, and black to the electrostatic latent image on the photosensitive drum 1.

In this copying machine, the developers of the respective colors carried on the developing roller 9 are sequentially supplied to the electrostatic latent image on the photosensitive drum 1, and the images of the respective colors are superposed and developed.
In this way, the developing roller 9 is supplied to the electrostatic latent image a plurality of times by using a plurality of developing devices, and in order to avoid color mixture, the developing roller 9 is fixed to the photosensitive drum 1 with a constant gap G (developing roller The distance between the center of the photosensitive drum and the surface of the photosensitive drum is required to be set.

Further, since the toner images of the respective colors are formed in an overlapping manner, in order not to disturb the toner images previously formed on the photosensitive drum 1, a developing roller for supplying the developer at least at the second time and thereafter. In the case of 9, the developer needs to be supplied with a certain gap from the photosensitive drum 1. Therefore, as described above, the gap rollers 10 are provided on both sides of the rotary shaft 11, the gap rollers 10 are brought into contact with the base of the photosensitive drum 1, and the gap G between the developing roller 9 and the photosensitive drum 1 is kept constant. Development is performed in this state.

[0006]

However, since the gap roller 10 is made of resin and the base of the photosensitive drum 1 is made of aluminum and has different hardness, the gap roller 10 wears over time and the developing roller 9 And the gap G between the photosensitive drum 1 and
This makes it impossible to form an appropriate image. Such a phenomenon similarly occurs when the hardness of the material forming the developing roller 9 is higher than the hardness of the material forming the base of the photosensitive drum 1. In particular, when the smoothness of the photosensitive drum 1 is lower than that of the gap roller 10, the gap roller 10 is worn by being scraped off by the photosensitive drum 31 as shown in FIG. Will be significant.

The present invention has been made by paying attention to the above-mentioned conventional problems, that is, the developing roller or the base of the photosensitive member is not worn, and the gap between the developing roller and the photosensitive member does not change with time. An object of the present invention is to provide an electrophotographic apparatus capable of always forming an appropriate image.

[0008]

According to a first aspect of the present invention, there is provided an electrostatic latent image carrier on which an electrostatic latent image is formed, and a developer supplied to the electrostatic latent image on the electrostatic latent image carrier. And a contact member that is provided on the side of the developer carrier and that contacts the electrostatic latent image carrier to keep the gap between the developer carrier and the electrostatic latent image carrier constant. In the electrophotographic apparatus having :, the contact portion between the contact member and the electrostatic latent image carrier is made of a material having the same hardness.

According to a second aspect of the present invention, an electrostatic latent image carrier on which an electrostatic latent image is formed, and a developer carrier for carrying a developer to be supplied to the electrostatic latent image on the electrostatic latent image carrier. And a contact member which is provided on the side of the developer bearing member and contacts the electrostatic latent image bearing member to keep the gap between the developer bearing member and the electrostatic latent image bearing member constant. In the electrophotographic apparatus, in the contact member and the electrostatic latent image carrier, the smoothness of the contact portion having a higher hardness is higher than the smoothness of the contact portion having a lower hardness.

[0010]

In the invention of claim 1, since the contact portion between the contact member and the electrostatic latent image carrier is made of a material having the same hardness,
Neither the contact member nor the electrostatic latent image carrier is worn. Therefore, the gap between the developer bearing member and the electrostatic latent image bearing member does not change over time. According to the second aspect of the present invention, the contact member and the electrostatic latent image bearing member have a higher smoothness in the contact portion than in the contact member and the electrostatic latent image bearing member. Wear of the carrier is prevented. Therefore, the gap between the developer bearing member and the electrostatic latent image bearing member does not change over time.

[0011]

Embodiments of the present invention will be described with reference to the drawings. In the embodiments, the same members as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. An embodiment corresponding to claim 1 will be described. Reference numeral 21 denotes a photoconductor drum, and on the peripheral surface of the photoconductor drum 21, a charging device 2, a yellow developing device 4a, a magenta developing device 4b, a cyan developing device 4c, a black developing device 4d, and a transfer separation charger. 5, a static eliminator 7 and a cleaning unit 8 are arranged.

As shown in FIGS. 1 and 2, the photosensitive drum 21
Both end portions 21a of are covered with polyacetal. It is formed by the gap roller 110. Therefore, the hardness of both ends 21a of the photosensitive drum 21 and the hardness of the gap roller 110 are the same. Gap roller 110
Are in contact with both ends 21a of the photosensitive drum 21.

Next, the operation of this copying machine will be described.
The photoconductor drum 21 rotates clockwise and is charged by the charger 2. Then, the exposure light 3 is irradiated to form an electrostatic latent image on the photosensitive drum 21. Then, development is performed by the yellow developing device 4a. Further, the development by the magenta developing device 4b, the cyan developing device 4c, and the black developing device 4d is performed in the same procedure.

The toner image formed on the photosensitive drum 21 is transferred to the transfer paper 6 by the transfer separation charger 5.
Further, the transfer paper 6 is separated from the photoconductor drum 21. Then, the transfer paper 6 is ejected out of the machine after the toner image is fixed. The photoconductor drum 21 further rotates in the clockwise direction, and after the charge is removed by the charge remover 7, the cleaning unit 8
To prepare for the next image forming operation.

In this copying machine, both ends 21a of the photosensitive drum 21 are covered with polyacetal and the gap rollers 110 are formed with polyacetal. Therefore, both members have the same hardness and are not worn, and the photosensitive member is aged with time. The gap G between the drum 21 and the developing roller 9 does not change.

As shown in FIG. 3, the circumferential surface of the gap roller 210 is covered with polyacetal to form the polyacetal layer 2
10a may be formed. Even with such a configuration, it is possible to obtain the same effects as the above. In addition to polyacetal, any material having high wear resistance can be used.

An embodiment opposed to claim 2 will be described. Since the copying machine according to the embodiment corresponding to claim 2 has a part having the same structure as the copying machine according to claim 1, the description of the part having the same structure is omitted as shown in FIG. A base made of aluminum is exposed at both end portions 31a of the photosensitive drum 31, and the gap roller 310 is made of resin.
The hardness of a is larger than that of the gap roller 310.

The smoothness of both ends 31a is set higher than that of the gap roller 310. Therefore, even if the both end portions 31a of the photoconductor drum 31 and the gap rollers 310 slide, the progress of wear of the gap rollers 310 is prevented, and the change of the gap G with time can be prevented.
The present invention is not limited to the above-mentioned ones, but can be applied to a driven roller that comes into contact with a transfer roller mounted on a copying machine or the like. The present invention can be applied not only to a copying machine but also to a facsimile and various printers.

[0019]

As described above, according to the present invention, the gap between the developing roller and the photosensitive member can be prevented from changing over time without causing the base body of the developing roller and the photosensitive member to be worn, and therefore, it is always appropriate. Image formation becomes possible.

[Brief description of drawings]

FIG. 1 is a plan view of a photosensitive drum and a developing device main part of a copying machine according to an embodiment corresponding to claim 1. FIG.

FIG. 2 is a side view of a photosensitive drum and a gap roller according to an embodiment corresponding to claim 1. FIG.

FIG. 3 is a side view of a photosensitive drum and a gap roller according to another embodiment corresponding to claim 1.

FIG. 4 is a plan view of a photosensitive drum and a developing device main part of a copying machine according to an embodiment corresponding to claim 2;

FIG. 5 is a side view of a photosensitive drum and a developing device main part of a copying machine according to an embodiment corresponding to claim 2;

FIG. 6 is a schematic configuration diagram of a copying machine according to an embodiment of the present invention.

FIG. 7 is a plan view of a photosensitive drum and a main part of a developing device of a copying machine according to a conventional example.

FIG. 8 is a diagram for explaining a problem of a copying machine according to a conventional example.

[Explanation of symbols]

 21 Photoreceptor Drum 31 Photoreceptor Drum 21a Both Ends 31a Both Ends 9 Developing Roller 110 Gap Roll 210 Gap Roll 210a Polyacetal Layer 310 Gap Roll

Claims (2)

[Claims] 1. An electrostatic latent image carrier on which an electrostatic latent image is formed,
A developer carrying body carrying a developer to be supplied to the electrostatic latent image on the electrostatic latent image carrying body, and the developer carrying body provided on the developer carrying body side in contact with the electrostatic latent image carrying body. In an electrophotographic apparatus having a body and a contact member for keeping a gap between the electrostatic latent image carrier and the electrostatic latent image carrier, a contact portion between the contact member and the electrostatic latent image carrier is made of a material having the same hardness. An electrophotographic device characterized by. 2. An electrostatic latent image carrier on which an electrostatic latent image is formed,
A developer carrying body carrying a developer to be supplied to the electrostatic latent image on the electrostatic latent image carrying body, and the developer carrying body provided on the developer carrying body side in contact with the electrostatic latent image carrying body. In an electrophotographic apparatus having a body and a contact member that keeps a gap between the electrostatic latent image carrier and the electrostatic latent image carrier constant, the smoothness of the contact member or the electrostatic latent image carrier having the higher hardness at the contact portion. The electrophotographic apparatus is characterized in that the hardness is higher than the smoothness of the lower hardness.