JPH10171142A - Organic photosensitive drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the peeling of edge parts of a coating film of a photosensitive material and to obtain an org. photosensitive drum having a prolonged service life by coating the edge parts with a protective material made of a polymer. SOLUTION: A coating film 2 of a photosensitive material is formed on the surface of a cylindrical photosensitive base body 1 and a protective material 15 is formed so as to coat edge parts of the coating film 2 in the peripheral direction. The protective material 15 is a polymer such as polyamide, PVC or polyester and the thickness is preferably about 5-40μm. The protective material 15 prevents the mechanical friction of the edge parts of the coating film 2 and suppresses the peeling of the edge parts. Even when the coating film 2 peels, electric conduction is prevented by the protective material 15 and a leak can also be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic photosensitive drum, and more particularly to an organic photosensitive drum for electrophotography which is used when an image is formed by an electrophotographic process such as a copying machine, a printer or a facsimile. .

[0002]

2. Description of the Related Art A photoreceptor is one of the most important components for forming a good image on a recording medium such as paper in a device using an electrophotographic technique such as a copying machine, a printer or a facsimile. A photoreceptor for electrophotography is usually a cylindrical substrate and is called a photosensitive drum. There is a coating called photosensitive material on the surface of the photosensitive drum, and in the electrophotographic forming process, the photosensitive material on the photosensitive drum surface is charged, and the charged portion is charged with the opposite charge to the photosensitive material. Colored particles called toner are attached by electrostatic force.

FIG. 4 is a sectional view of an electrophotographic forming apparatus including a photosensitive drum for electrophotography. A photosensitive material coating 2 is formed on the surface of a photosensitive body 1 made of a conductive material such as aluminum. The photosensitive drum 3 composed of these is shown in FIG.
As shown in the overall view of the organic photosensitive drum substrate shown in FIG. Further, the photosensitive material coating film 2 is formed uniformly on the surface of the photosensitive body 1 as shown in the longitudinal sectional view of the conventional organic photosensitive drum body shown in FIG. Hereinafter, components provided in the electrophotographic forming apparatus will be described in the order of rotation of the photosensitive drum 3. First, a charger 4 is in contact with the photosensitive material coating film 2. In this case, the charger 4 using the charging brush 5 is illustrated. Next, a developing device 6 is provided. The developing device 6 has a developing roller 7 and supplies a toner 8 as a developing material to the photosensitive drum 3. Next, a transfer roller 9 is provided, and a recording medium 10 such as paper is supplied between the photosensitive drum 3 and the recording medium 10. Next, a cleaning unit 9 is provided. The cleaning unit 9 has a cleaning blade 10 and is close to the surface of the photosensitive drum 3.

Hereinafter, a more detailed electrophotographic forming process will be described with reference to FIG. (1) Charging Step: Step of Charging the Photoconductor to Give Photosensitivity The entire surface of the photosensitive material coating film 2 on the photosensitive drum 3 is electrically negatively charged by the charger 4 having the charging brush 5. (2) Exposure Step: Step of Forming an Electrostatic Latent Image on the Charged Photoconductor By irradiating the surface of the photosensitive material coating 2 of the photosensitive drum 3 with a laser beam or the like, the exposed surface of the photosensitive material coating 2 is exposed. It becomes electrically positive. By this irradiation, an electrostatic latent image corresponding to an image to be formed on the recording medium 10 is formed on the surface of the photosensitive drum 3. (3) Developing step: a step of attaching toner to the electrostatic latent image portion of the exposed photoreceptor The toner 8 that is electrically negatively charged by the developing roller 7 of the developing device 6 It is attracted and attached by electrostatic force to a portion that is electrically positively charged in the exposure step. (4) Transfer step: a step of transferring the toner image on the photoreceptor to a recording medium such as paper The toner 8 attached to the surface of the photosensitive drum 3 by the transfer roller 9 which is electrically positive is transferred to the transfer roller 9 To the side electrically. At this time, the toner 8 electrically attracted by the transfer roller 9 adheres to a recording medium 10 such as paper interposed between the transfer roller 9 and the photosensitive drum 3. The toner 8 attached to the recording medium 10 is fixed in another fixing step. (5) Cleaning step: a step of removing and cleaning the toner remaining on the photoconductor without being transferred The toner 8 remaining on the surface of the photosensitive drum 3 without being transferred is scraped off by the cleaning blade 12 to clean the surface of the photosensitive drum 3. . (6) Static elimination step: a step of removing the charge on the surface of the photoreceptor A weak light is applied to remove the charge on the photosensitive drum 3.
The steps (1) to (6) are repeated again on the photosensitive drum from which the charge has been removed, and the electrophotographic formation is continued. Further, the toner 8 adhered to the recording medium 10 with a weak electric force in the transfer process is fixed in a fixing process different from these processes.

[0005] As described above, the photosensitive material in the electrophotographic forming process is important in carrying out the electrophotographic forming step. In electrophotography, the amount of adhered toner is controlled by finely controlling the charge amount and charged portion of the photosensitive material, and a complex image is formed. The photosensitive material must be reliably charged and its state must be accurately maintained. The performance and condition of the photosensitive material greatly affect the image quality of the formed electrophotograph.

[0006] The photosensitive material is an organic material, an inorganic material, a composite thereof or the like. The photosensitive material applied and formed on the surface of the cylindrical photosensitive drum for electrophotography exists only on the surface of the photosensitive drum that performs electrophotography. No photosensitive material is required at the end of the cylindrical substrate other than the area that can be recorded on a recording medium without being used for exposure. Using photosensitive material of organic material,
In order to form a photosensitive material coating on the surface of the cylindrical substrate, the photosensitive material is not previously applied to the end of the cylindrical substrate, or an excess coating film is peeled off after the application.

[0007]

However, the conventional organic photosensitive drum has the following problems.
The photosensitive material coating on the photosensitive drum is inevitably subjected to mechanical friction in performing the electrophotographic forming process. Therefore, the surface is peeled off or cut by friction. In particular, since the end of the coating film is exposed, peeling is more likely to occur than near the center in the longitudinal direction of the photoreceptor substrate. This is selenium or selenium
When a photosensitive material made of an inorganic material such as tellurium alloy is used, there is no problem. However, when an organic photosensitive material is used, peeling is likely to occur because the hardness is lower than that of an inorganic photosensitive material.

Hereinafter, a state in which the coating film of the photosensitive material is peeled off will be described with reference to the drawings. In the electrophotographic forming process, the photosensitive material coating film 2 on the organic photosensitive drum for electrophotography is subjected to mechanical friction by the charging brush 5, the developing roller 7 of the developing device 6, the cleaning blade 12 of the cleaner unit 11, and the like.
When subjected to mechanical friction, the photosensitive material coating 2 is worn, and as the wear progresses, the photosensitive material coating 2 is peeled off. In particular, peeling is more likely to occur at the end of the photosensitive material coating film 2 than near the center of the photosensitive body 1 in the longitudinal direction.

FIG. 6A is a longitudinal sectional view of a part of a component including a conventional organic photosensitive drum for electrophotography. Due to mechanical friction, the end of the photosensitive material coating film 2 is peeled off, and the photosensitive body 1 of the photosensitive drum 3 is exposed. FIG.
FIG. 6B is a cross-sectional view in the longitudinal direction of a part of components different from FIG. 6A and a conventional organic photosensitive drum. When the photosensitive material coating film 2 peels off, it may come into contact with the charging brush 5 used in the charging step. Depending on the peeling state of the end of the photosensitive material coating film 2, the tip of the charging brush 5 comes into contact with the photosensitive body 1,
It becomes electrically conductive.

Further, when a gear for rotating the organic photosensitive drum is provided in the cylindrical substrate of the photosensitive drum during the production of the organic photosensitive drum, the photosensitive material coating film may be peeled off. FIG. 7 is a longitudinal sectional view when a gear is press-fitted into the conventional organic photosensitive drum shown in FIG. Gear 13
After the terminal 14 is fitted into the photoreceptor substrate 1 for rotation prevention and electrical continuity, the terminal 14 is pressed into the photoreceptor base 1. The diameter of the terminal 14 is substantially equal to the inner diameter of the cylinder so that the terminal 14 is stabilized in the cylindrical photosensitive body 1. Therefore, when the terminal 14 is press-fitted into the end of the cylindrical photoconductor substrate 1, the inside of the cylinder is expanded and the portion of the photoconductor substrate 1 in contact with the terminal 14 is expanded.
Pressure may be applied to the outside of the photosensitive material coating film 2 to cause a crack at the end of the photosensitive material coating film 2 and peel off (a peeled portion a). If the photosensitive material coating film 2 is cracked or peeled off, the surface of the photoreceptor substrate 1 and the bristle tip of the charging brush 5 come into contact with each other and become electrically conductive.

As described above, when the base material and the photosensitive material coating are electrically connected to each other through the brush of the charger due to peeling or cracking of the photosensitive material coating, the negative charge in the photosensitive material charged in the charging step is reduced. Flows to the photoreceptor substrate, and the electric charge becomes 0, and as a result, a part or the whole of the surface of the photosensitive material becomes electrically positive. This phenomenon is called leak. When the toner adheres to the electrically positive portion and is transferred to the recording medium, an image other than the image exposed in the exposure step is transferred, resulting in an image defect. When the leak state becomes remarkable, the entire outer surface of the photosensitive drum becomes electrically positive, as if the entire surface was exposed. In this case, the toner adheres to the entire surface in the developing process, and no longer serves as a photosensitive drum for electrophotographic formation. Further, when the photosensitive material coating film is peeled off, the life of the photosensitive drum is significantly shortened.

The problem to be solved by the present invention is that an organic film capable of preventing peeling of an end portion of a coating film of a photosensitive material, which causes a problem of deterioration of image quality of electrophotography, and at the same time, improving the life as a photosensitive drum. It is to provide a photosensitive drum.

[0013]

According to a first aspect of the present invention, there is provided an organic photosensitive drum, wherein a protective material made of a polymer material covers an end of the photosensitive material coating film.

According to a second aspect of the present invention, in the organic photosensitive drum according to the first aspect, the polymer material contains one or more selected from the group consisting of polyamide, polyvinyl chloride, and polyester. It is characterized by.

According to a third aspect of the present invention, in the organic photosensitive drum according to the first or second aspect, the thickness of the polymer material is 5 to 40 μm.

The organic photosensitive drum of the present invention has a protective material at the end of the photosensitive material coating on the surface of the cylindrical substrate of the electrophotographic photosensitive member. The protective material is formed so as to cover a part of the end, and prevents peeling from the end due to friction or the like. Therefore, the material must have high mechanical strength. However, until the end of the life of the photosensitive drum, it is sufficient if the end has a hardness enough to protect the end, and it is not necessary to have the same hardness as a metal such as a base of the photosensitive drum. As the protective material, it is appropriate to select a material whose resistance value is equal to or higher than the resistance value of the coating film of the photosensitive material. If necessary, an insulating material is selected. This is to prevent the negative charges charged in the charging step from leaking electrically to the base. As a protective material suitable for these conditions, there is a polymer material such as polyamide, polyvinyl chloride, and polyester. They are also excellent in ease of formation and cost. A protective material is formed using one or more of these materials.

As for the protective material at the end of the photosensitive material, after applying the photosensitive material, a resinous protective material is formed so as to cover the end of the coating film of the photosensitive material. Depending on the characteristics of the organic material used as the protective material, a formation method of forming by a dipping method, a vacuum evaporation method, a sputtering method, or the like is selected. In the formation of the protective material by the dipping method, first, the protective material is dissolved in a solvent, and the substrate is once immersed in the solution and then pulled up, whereby the solvent containing the protective material adheres to the surface of the substrate. Next, the solvent in the protective material-containing solvent is volatilized by drying to fix the protective material on the substrate surface. The formation of the protective material by the vacuum evaporation method is performed by heating and evaporating the protective material in a vacuum, and attaching the vapor to the substrate. The formation of the protective material by the sputtering method utilizes the sputtering phenomenon in which high-energy protective material particles collide with the target substrate, and the atoms and molecules on the substrate surface exchange momentum with the impinging particles, and are repelled from the surface. It is done. By forming the protective material in this way, even if a crack occurs when the gear is pressed into the photosensitive drum, electric leakage can be prevented because of electrical insulation.

The thickness of the protective material is suitably about 5 to 40 μm. This is about the same as the thickness of the photosensitive material coating film of a normal organic photosensitive drum, and is a thickness that can be maintained until the service life of the organic photosensitive drum even if cutting due to friction occurs.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an organic photosensitive drum for electrophotography according to the present invention. FIG. 1A shows an overall view of the photosensitive drum substrate. Also, FIG. 1B shows FIG.
1 is a cross-sectional view in the longitudinal direction of the organic photosensitive drum substrate of FIG. A photosensitive material coating 2 is provided on the surface of the cylindrical photosensitive body 1. A protective material 15 is formed in the circumferential direction of the cylindrical surface so as to cover a part of the end of the photosensitive material coating 2. This protective material 1
The thickness of 5 is about 5 to 40 μm. Thus, the photosensitive drum 3 of the present invention is formed.

FIG. 2 shows an electrophotographic forming apparatus including the electrophotographic photosensitive drum of the present invention. FIG. 2A shows an overall view of some components of an electrophotographic forming apparatus including an organic photosensitive drum. A protective material 15 is provided between the charging brush 5 and the cleaning blade 12 at the end of the photosensitive material coating 2. The protective material 15 can prevent the end of the photosensitive material coating 2 from being directly subjected to mechanical friction from the charging brush 5, the cleaning blade 12, and the like, and can prevent the end of the photosensitive material coating 2 from peeling.

FIG. 2B is a cross-sectional view in the longitudinal direction including the charger 4 and the organic photosensitive drum which are other components different from FIG. 2A. Since the bristle tips of the charging brush 5 of the charger 4 do not come into contact with the photosensitive material coating film 2 by the protective material 15, it is possible to prevent a leak state.

FIG. 3 is a longitudinal sectional view of an electrophotographic forming apparatus including a gear for rotating the organic photosensitive drum inside the electrophotographic photosensitive drum shown in FIG. As described above, when the terminal (not shown) is inserted into the inside of the photosensitive material base 1 and a gear (not shown) is press-fitted, the portion of the photosensitive body 1 that is in contact with the terminal (not shown) Pressure may be applied to the outside of the film, and the photosensitive material coating film 2 may be cracked. At this time, since the protective material 15 also covers the crack, the tip of the charging brush 5 of the charger 4 is
Is prevented from contacting with the surface of the photosensitive material coating 2 in the exposure step, and the electric charge charged to the photosensitive material coating film 2 in the exposing step can be prevented from leaking to the photosensitive body 1 via the charging brush 5 of the charger 4.

[0023]

Since the present invention is configured as described above, it has the following excellent effects.
A protective material made of a polymer material is formed so as to cover the end of the coating film of the photosensitive material on the surface of the cylindrical substrate of the organic photosensitive drum for electrophotography. The protective material prevents mechanical friction at the edges of the coating film of the photosensitive material, and as a result, peeling of the edges of the coating film can be significantly reduced. Further, even when the photosensitive material coating film is peeled off, electrical conduction can be prevented by the protective material, and occurrence of a leak state can be prevented. Further, when the gear is pressed into the inside of the base with the terminal interposed therebetween, even if a crack occurs in the photosensitive material coating film, the presence of the protective material prevents electrical conduction, prevents leakage, and prevents image defects. . Since the production yield can be improved in this way, the cost of the product can be reduced.

[Brief description of the drawings]

FIG. 1 is a view for explaining an organic photosensitive drum of the present invention, wherein (a) is an overall view of an organic photosensitive drum base;
FIG. 2B is a longitudinal sectional view of the organic photosensitive drum substrate of FIG.

FIG. 2 is a view when an organic photosensitive drum is arranged in an electrophotographic forming apparatus having the organic photosensitive drum of the present invention, and FIG. 2 (a) is an overall view of a part of components including the organic photosensitive drum. (B) is a longitudinal sectional view including a part of components different from (a) and an organic photosensitive drum.

FIG. 3 is a view for explaining the organic photosensitive drum of the present invention, and is a longitudinal sectional view when a gear is press-fitted in the organic photosensitive drum shown in FIG. 2;

FIG. 4 is a cross-sectional view of an electrophotographic forming apparatus including a photosensitive drum for electrophotography for explaining the concept of the electrophotographic process.

5A and 5B are diagrams illustrating a case where an organic photosensitive drum is arranged in an electrophotographic forming apparatus having a conventional electrophotographic photosensitive drum, wherein FIG. 5A is an overall view of a conventional organic photosensitive drum base, and FIG. (A) is a longitudinal sectional view of the conventional organic photosensitive drum substrate of (a).

6A and 6B are views for explaining a conventional organic photosensitive drum for electrophotography, and FIG. 6A is an overall view of some components of an electrophotographic forming apparatus including the conventional organic photosensitive drum;
(B) is a longitudinal cross-sectional view of a part of another component different from (a) and a conventional organic photosensitive drum.

7 is a view for explaining a conventional organic photosensitive drum for electrophotography, and is a longitudinal sectional view when a gear is pressed into the conventional organic photosensitive drum shown in FIG. 6;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor substrate 2 photosensitive material coating 3 photosensitive drum 5 charging brush 8 toner 13 gear 14 terminal 15 protective material a peeling part

Claims (3)

[Claims] 1. An organic photosensitive drum, wherein a protective material made of a polymer material covers an end portion of a coating film of the photosensitive material. 2. The organic photosensitive drum according to claim 1, wherein the polymer material includes one or more members selected from the group consisting of polyamide, polyvinyl chloride, and polyester. 3. The organic photosensitive drum according to claim 1, wherein the thickness of the polymer material is 5 to 40 μm.