JPH0728360A - Soft photoreceptor - Google Patents

Abstract

PURPOSE:To improve the restoration ability of a soft photoreceptor and also to improve the workability at the time of forming the photoreceptor and to obtain an image having no distortion by using an endless belt as a photoreceptor base material and enclosing fluid in the cylinder formed by the endless belt and forming the photoreceptor to a roll shape. CONSTITUTION:The photoreceptor is constituted of a belt photoreceptor 9, a core bar 11 and a sheet-like elastic cap 12 which is formed of an elastic body in order to enclose gas, or liquid 13 therein. When the soft photoreceptor abuts on a developing roller, the belt photoreceptor 9 is recessed. An abutting pressure is transmitted to the elastic cap 12 by the gas, or the liquid 13 enclosed therein, then, the sheet-like elastic cap 12 swells outwardly by the same amount of the recessed cubic content of the belt photoreceptor 9. Thus, on the belt photoreceptor 9, a part abutting on the developing roller is kept in a recessed state, and when the abutting part is moved in accordance with the rotation, the part is restored to a state before it is recessed by the time the process is shifted to the next one, so that the image having no distortion can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive member applied to a one-component contact type developing device.

[0002]

2. Description of the Related Art In the one-component developing system, the contact time between the photosensitive member and the developing roller is the developing time. In order to increase the developing efficiency, the longer the developing time is, the better, but the following method can be considered as a method therefor. 1) Increase the linear velocity ratio of the developing roller to the photoconductor. 2) Increase the diameter of one or both of the photoconductor and the developing roller. 3) One or both of the photoconductor and the developing roller are softened to increase the contact area (see FIGS. 4 and 5: FIG. 4 shows a case where a belt photoconductor is used to soften the photoconductor, and FIG. 4 uses a hard drum photosensitive member 8 and a soft developing roller 7. In FIGS. 4 and 5, 1 is a hard developing roller, 2 is a belt photosensitive member, 3 is an image forming unit, and 4 is an image forming unit.
Is a charging unit, 5 is a cleaning unit, and 6 is a transfer unit. )

The method 1) has a problem that the image processing speed becomes slow, and the method 2) makes the machine large and it is difficult to reduce the size and weight. The method that has been conventionally adopted is 3), but a belt photoreceptor has been used as a method for softening the photoreceptor.

However, even if the belt photoreceptor is miniaturized by using a seamless belt, it requires three or more rollers such as a driving roller and a tension roller, which complicates the driving system and increases the cost.

A soft photosensitive member was conceived there. As shown in FIG. 6, a conventional soft photoreceptor has a seamless roller in which a soft roller 10 made of sponge rubber, soft rubber or the like is press-fitted (Japanese Patent Laid-Open No. HEI 2).
104372)

[0006]

However, in general, soft rubber and sponge rubber have a low restoring force instead of flexibility. In this type of photoconductor, if the place where it was in contact with the developing roller is not restored when it is moved to the next transfer step or the like, the image on the transfer paper or the image on the photoconductor is distorted.

Further, when the soft roller is press-fitted into the seamless belt, it is difficult to press-fit it evenly, and the surface of the belt photosensitive member 9 is greatly shaken with respect to the core metal 11, resulting in image distortion. There's a problem.

The present invention is intended to solve the above-mentioned problems, and its purpose is to improve the restorability of a soft photoconductor and restore it when the portion in contact with the developing roller moves to the next transfer step. The present invention provides a soft photoconductor capable of giving an image free from distortion and further improving the processability when forming the photoconductor to eliminate the distortion of the photoconductor itself, thereby giving an image without distortion. is there.

[0009]

The soft photosensitive member according to claim 1 is a one-component contact developing type photosensitive member, and is formed by the endless belt using an endless belt as a photosensitive member base material. It is characterized in that a fluid is enclosed in the inside of the cylinder to form a roll.

According to a second aspect of the present invention, in the soft photoconductor, sheet-like elastic caps are attached to both ends of the cored bar.
It is characterized in that the elastic cap and the both ends of the cylinder formed by the endless belt are in close contact with each other to seal the fluid.

The soft photosensitive member according to a third aspect is characterized in that an elastic cap having a Young's modulus lower than that of the endless belt of the photosensitive member base is used.

According to a fourth aspect of the present invention, the soft photoconductor is characterized in that the material hardness of the elastic cap is 60 or less as measured by JIS-A hardness meter, and the thickness of the elastic cap is 4 mm or less.

[0013]

The present invention will be described in more detail with reference to the examples shown in the drawings. FIG. 1 is a front view with a partial cross section showing an embodiment of a soft photoconductor of the present invention. The soft photosensitive member of FIG. 1 includes a belt photosensitive member 9, a core metal 11, and a sheet-shaped elastic cap 12 which is an elastic material for enclosing gas or liquid inside.

As shown in FIG. 2, in the soft photosensitive member of the present invention, when it comes into contact with the developing roller 1, the belt photosensitive member 9 is recessed. The gas or liquid enclosed inside transmits the contact pressure to the elastic cap 12, and the elastic cap 12 in the form of a sheet bulges outward by the same amount as the recessed portion of the belt photosensitive member 9.

As a result, the portion of the belt photosensitive member 9 that is in contact with the developing roller 1 is in a recessed state, but if the contacted portion moves due to rotation, it will be recessed before moving to the next step. Since the state is restored to, the image formation without distortion becomes possible.

A fluid (gas or liquid) is enclosed in a space surrounded by the belt photosensitive member 9, the core metal 11 and the sheet-like elastic cap 12, and the sheet-like elastic cap 12 is a space. Since it can swell and recover due to pressure fluctuation during the period, it can be assembled without distortion of the photoreceptor itself when assembled to the soft photoreceptor, which also enables image formation without distortion. .

The material hardness of the elastic cap 12 is preferably 60 or less as measured by the JISA hardness tester, and the thickness of the film portion 15 is preferably 4 mm or less. The elastic cap 12 is fixed to the belt photoreceptor 9 and the cored bar 11 while being sealed with an adhesive or the like.

Examples of the elastic material used for the sheet-like elastic cap 12 include silicone rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, nitrile butadiene rubber, chloroprene rubber, butyl rubber, urethane rubber, and thermoplastic elastomer. Examples of the thermoplastic elastomer include polyvinyl chloride-based, olefin-based, and polyester-based thermoplastic elastomers.

When these elastic materials are used for a sheet-like elastic cap, carbon black may be added to provide conductivity, or some reinforcement may be required, as shown in FIG.
Fibers 14 may be incorporated as shown in (a) and (b).

The fluid (gas or liquid) to be enclosed should be selected so that it does not corrode the elastic cap 12 and does not undergo a phase change at -40 ° C. to 70 ° C., which is the environment of use and storage of the apparatus body. is there. For example, gas such as air and nitrogen can be used, and liquid such as ethylene glycol or an aqueous solution thereof can be used.

[0021]

According to the soft photosensitive member of the first aspect, since the fluid is enclosed, the recess of the belt photosensitive member which is in contact with the developing roller is restored by the internal pressure when it is separated from the developing roller. Since the surface is uniform, a normal image without distortion can be obtained, and the entire image forming unit is compact and high-speed processing is possible. According to the soft photosensitive member of the second aspect, by using the sheet-like elastic cap, it becomes possible to make the photosensitive member a soft drum-shaped photosensitive member by bulging only the concave portion of the belt photosensitive member. . According to the soft photoconductor of the third aspect, since the Young's modulus of the elastic cap is lower than that of the belt photoconductor, the elastic cap can absorb the amount of depression caused by the contact with the developing roller. According to the soft photoreceptor of claim 4, by setting the material hardness of the elastic cap to 60 or less by the JIS-A hardness tester and the thickness to 4 mm or less,
The Young's modulus of the elastic cap can be made smaller than that of the belt photosensitive member, and the elastic cap can be deformed more easily. Further, by using the elastic cap according to the fourth aspect, the thermal expansion and the thermal contraction due to the environment of the enclosed fluid can be absorbed by the elastic cap without affecting the belt photosensitive member.

[Brief description of drawings]

FIG. 1 is a front view with a partial cross section showing an embodiment of a soft photosensitive member of the present invention.

FIG. 2 is an explanatory view showing a state where a soft photosensitive member of the present invention and a hard developing roller are in contact with each other.

3A and 3B show an example of reinforcement of an elastic cap used in the soft photoconductor of the present invention, in which FIG. 3A is a front view and FIG. 3B is a side view.

FIG. 4 is a schematic configuration diagram showing an image forming system using a conventional belt photosensitive member-hard developing roller.

FIG. 5 is a schematic configuration diagram showing an image forming system using a conventional hard drum photosensitive member-soft developing roller.

FIG. 6 is a cross-sectional view schematically showing an example of a conventional soft photoconductor.

[Explanation of symbols]

 1 Hard Developing Roller 2 Belt Photosensitive Body 3 Imaging Unit 4 Charging Unit 5 Cleaning Unit 6 Transfer Unit 7 Soft Developing Roller 8 Hard Drum Photosensitive Body 9 Belt Photosensitive Body 10 Soft Roller 11 Core Bar 12 Elastic Cap 13 Fluid (Gas or Liquid) 14 fiber 15 membrane part

Claims (4)

[Claims] 1. A one-component contact developing type photoconductor, wherein an endless belt is used as a photoconductor base material, and a fluid is enclosed in a cylinder formed by the endless belt to form a roll. And a soft photoconductor. 2. A sheet-shaped elastic cap is attached to both ends of the core metal, and the elastic cap and the both ends of a cylinder formed of an endless belt are in close contact with each other to seal the fluid. Soft photoconductor. 3. An elastic cap having a Young's modulus lower than that of the endless belt of the photoconductor substrate is used.
The soft photosensitive member described in. 4. The soft photoconductor according to claim 1, wherein the material hardness of the elastic cap is 60 or less as measured by JIS-A hardness tester, and the thickness of the elastic cap is 4 mm or less.