JPH09114105A - Photosensitive member drum and electrophotography device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive member drum which is provided with a cylindrical base body, in which uniform thickness is provided while highly precise cylindricity and circularity are provided in its inner circumference face and in its outer circumference face, and generates no image fog by molding the inner circumferential face by means of a roller during production when polymerizing liquid material is polymerized. SOLUTION: A center shaft 113 is inserted into a cylindrical die 111 while ring type side plate are fitted in both ends, synthesized plastic material with a catalyst is injected into the inside of a molding die 100, and the side plates are fixed in the die 111. Steam is let flow into the inside of a steam chamber 110 while the molding die 100 is rotated at a high speed, and centrifugal polymerization is carried out, and consequently, a cylindrical base body 1 is produced. In this process, gears fixed on the side plates and integrated two gears journalled to an arm 114b are driven and rotated when a gear is rotated, and a roller 115 arranged inside the die 111 is rotated on an inner circumferential face of the cylindrical base body 1 by means of a gear which is fixed in the supporting shaft and connected to the gear.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer, an F
The present invention relates to a photosensitive drum used in an image forming apparatus such as AX. In particular, it relates to an electrophotographic photosensitive drum.

[0002]

2. Description of the Related Art Conventionally, as a base material of a cylindrical (drum-shaped) photosensitive drum used in an image forming apparatus such as a copying machine, a printer, and a FAX, a metal material such as aluminum is used to ensure roundness and strength. Many are made using.

On the other hand, plastic is considered to be a preferable material because of its light weight and low cost, but it is not easy to manufacture a photosensitive drum with high accuracy and industrially efficiently. The major factor is the diameter of 50 to 200 mm
It was because we could not find a method for easily and easily manufacturing the cylindrical substrate of 3) with cylindricity and circularity of about 30 μm which are required for image formation. Therefore, conventionally, after molding the cylindrical substrate, it is necessary to secure the accuracy by cutting and polishing the surface, which leads to a decrease in productivity and an increase in cost. Further, it has a defect that it is weak against heat and solvent, and in addition to the accuracy of the surface of the substrate, strength and change with time become problems.

On the other hand, as one of methods for forming a multicolor image, a color image is formed by sequentially performing charging, image exposure and development for each color within one rotation of one image forming body to form a color image. The device is known.

However, although the above-mentioned color image forming apparatus enables high-speed image formation as a method of forming a multicolor image, a charging unit, an image exposing unit and a developing unit are provided within one rotation of the photosensitive member. It is necessary to arrange multiple sets of
The image exposure means may be contaminated by toner leaking from the adjacent developing means and impair the image quality, and in order to avoid this, it is necessary to increase the distance between the image exposure means and the developing device, so the diameter of the photoconductor is inevitably increased There is a drawback that the apparatus becomes large in size. For the purpose of avoiding this drawback, a photoconductor substrate is formed of a transparent material, a plurality of image exposure means are accommodated therein, and an image is exposed on the photoconductor layer formed on the outer periphery thereof through the substrate. An apparatus has been proposed, for example, in Japanese Patent Application Laid-Open No. 5-307307.

[0006]

Although an excellent cylindrical substrate made of plastic for the photosensitive drum of the above-mentioned color image forming apparatus has been desired, it has not been put into practical use at present. It was

As a result of research conducted by the present inventors, in order to synthesize and polymerize a plastic material monomer in a cylindrical mold 406 shown in FIG. 6 as a cylindrical substrate for a photosensitive drum of the color image forming apparatus. After adding the catalyst of (1), the mixture was poured into a cylindrical mold, the left and right side plates 407a, 407b were fixed with screws 408, and this was rotated at high speed, while being moderately heated to promote uniform polymerization, A method was developed to post-cool and produce a transparent cylindrical substrate.

However, in the cylindrical substrate produced by the above-mentioned manufacturing method using centrifugal polymerization, although the cylindricity and the roundness of the outer peripheral surface can obtain the desired accuracy, the wall thickness becomes uneven and the inner peripheral surface No cylindricity or roundness was obtained. Therefore, when it is used as a photoconductor drum of the above-mentioned color image forming apparatus, the image exposure light from the image exposure means is not focused correctly, which causes image blurring.

As a result of improving the present invention to solve this point, image blurring occurs when a cylindrical substrate having a uniform wall thickness and highly accurate cylindricity and roundness on both the inner and outer peripheral surfaces is provided. It is an object of the present invention to provide a photoconductor drum that does not have a photoconductor and an electrophotographic apparatus using the photoconductor drum.

[0010]

The above object is a photosensitive drum having a transparent cylindrical substrate and a photosensitive layer provided on the outer peripheral surface of the cylindrical substrate, wherein the cylindrical substrate comprises: A polymerizable liquid material is injected into a cylindrical mold, and when the polymerizable liquid material is polymerized while rotating the cylindrical mold, the inner peripheral surface is molded by a roller to be manufactured. This is achieved by a photosensitive drum (first invention).

Further, the above object is to provide a transparent cylindrical substrate,
A photoconductor drum having a photoconductor layer provided on an outer peripheral surface of the cylindrical substrate, wherein the cylindrical substrate is prepared by injecting a polymerizable liquid material into a cylindrical mold and rotating the mold. When the polymerizable liquid material is polymerized, the inner peripheral surface is molded by the roller, and the roller is driven at the same peripheral speed as the peripheral speed of the inner surface of the cylindrical substrate. An electrophotographic apparatus comprising: a body drum; and an image exposure unit provided inside the photoconductor drum for exposing the photoconductor drum. It is achieved by (second invention).

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a cylindrical substrate made of plastic for a photosensitive drum according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a process of a method for manufacturing a cylindrical substrate for a photosensitive drum of the present invention, and FIG. 2 is a sectional view showing an embodiment of a molding die for manufacturing a cylindrical substrate. Three
FIG. 3 is a side sectional view of FIG. 2.

Arms 114a and 114b are fixed to a central shaft 113 of a mold 100 for centrifugal polymerization of plastics,
Support shafts 116a and 116b provided at both ends of the roller 115 are fitted into the tip ends of the arms 114a and 114b, and the roller 115 is rotatably attached. A gear G5 is fixedly provided on the support shaft 116b.

The central shaft 113 is inserted into the cylindrical mold 111, and the circular side plates 112a and 112b are fitted at both ends to synthesize a plastic material, for example, a methyl methacrylate monomer, and a catalyst for promptly polymerizing it. The added material is poured into the molding die 100, and the side plate 11
2a and 112b are fixed to the cylindrical mold 111 with screws 151.

The mold 100 is inserted into the steam chamber 110, and the central shaft 113 is attached to a fixing plate (not shown). Gear G11 provided at the end of the circumference of the side plate 112b
2 and a gear G1 connected to a drive motor (not shown) fixed to the chamber 110 are coupled to each other, so that the cylindrical mold 111 can rotate about the central axis 113.

With the mold 100 rotated at high speed,
Steam is introduced through the intake port 110a and the exhaust port 110b,
The cylindrical substrate 1 is introduced into the steam chamber 110, the polymerization is promoted by heating the steam, and the centrifugal polymerization is performed.
Is manufactured. At this time, when the gear G1 is rotated by a drive motor (not shown), the gear G fixed to the side plate 112b.
2. The gears G3 and G4, which are rotatably supported by the arm 114b, are driven and rotated, and the roller 115 provided inside the cylindrical mold 111 is replaced by the support shaft 116 of the roller 115.
It is rotated on the inner peripheral surface of the cylindrical substrate 1 by a gear G5 which is fixed to b and which is connected to the gear G4.

The rotation speed of the roller 115 is the same as the rotation speed of the inner peripheral surface of the cylindrical substrate 1. By rotating at a constant speed, the inner peripheral surface of the cylindrical substrate 1 is not scratched.

After the completion of the polymerization, it is cooled, the obtained cylindrical substrate 1 is taken out from the mold, cut, and if necessary, a finishing process is performed to manufacture a cylindrical substrate for a photosensitive drum of an image forming apparatus.

The plastic cylindrical substrate produced by the above-mentioned manufacturing method is a transparent substrate having a light transmittance of 90%, has a strength comparable to that of aluminum, and has an impact resistance performance 15 times that of glass and a wall thickness. Is uniform, and both the inner and outer peripheral surfaces have highly accurate cylindricity and roundness of about 30 μm. In addition, compared to the extrusion method, which is widely used at present, the die is not left on the outer peripheral surface of the cylindrical substrate, it is formed on a natural surface obtained by centrifugal force, and the inner peripheral surface is also formed by rollers. As a result, a smooth surface such as a glass surface is formed. Moreover, the strength is higher than that of the cylindrical substrate obtained by the extrusion method, the mechanical strength is stable without directivity, and the heat deformation temperature is excellent, and it is most suitable for use in the photoconductor drum.

The structure of the photosensitive drum of the present invention will be described with reference to FIG. FIG. 4 is a sectional view showing an embodiment of the structure of the photosensitive drum of the present invention.

The photosensitive drum 10 comprises a transparent plastic cylindrical substrate 1 molded by centrifugal polymerization described with reference to FIGS. 1 to 3, and a conductive layer 2 formed on the outer peripheral surface of the cylindrical substrate 1. It is composed of an organic photoconductor layer (OPC) 3 as a photoconductive photoconductor layer formed on the outer periphery of the conductive layer 2.

As a material for the transparent plastic cylindrical substrate 1 molded by centrifugal polymerization, a polymer obtained by using a methyl methacrylate monomer as described above is the best in terms of transparency, strength, precision and surface property. However, other polyethyl methacrylate, polybutyl methacrylate, polyethyl acrylate, polybutyl acrylate, polystyrene, polyimide, polyester, polyvinyl chloride, or the like, or copolymers thereof can be used.

As the conductive layer 2, indium tin oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, a metal thin film made of Au, Ag, Ni, Al or the like, ITO or alumina. A conductive resin in which conductive fine particles and a resin are mixed is used, and as a film forming method, a vacuum vapor deposition method, an active reaction vapor deposition method, various sputtering methods, various CVs are used.
D method, dip coating method, spray coating method and the like are used.

The organic photoconductor layer 3 is composed of a charge generating substance (CG
M) as a main component of charge generation layer (CGL) 4 and charge transport material (CTM) as a main component of charge transport layer (CTL) 5
And a two-layered photosensitive layer whose functions are separated. Since the organic photosensitive layer having a two-layer structure has a thin CGL, it has good transparency to image exposure light and is suitable for the present invention. The organic photoreceptor layer 3 may have a single layer structure containing a charge generating substance (CGM) and a charge transporting substance (CTM) in one layer, and the photosensitive layer having the single layer structure or the two layer structure. Usually contains a binder resin.

In the photosensitive drum having the organic photosensitive layer having the two-layer structure, the CGM contained in CGL4 is an azo pigment, an azurenium pigment, a phthalocyanine pigment, which is sensitive to light from a light source such as an LED or LD. Perylene pigments are used, among which infrared light (700 nm to 8 nm) is used.
The CGM of the OPC photoreceptor sensitive to 50 nm) is as follows.
A titanyl phthalocyanine pigment is preferably used.

As the binder resin used for CGL4, a polyvinyl butyral resin or a polycarbonate resin is used, which is excellent in sensitivity and potential change during repeated use. These binder resins can be used alone or as a mixture of two or more.

As the solvent or dispersion medium used for the formation of CGL4, a ketone-based or halogen-based solvent is preferably used, and sensitivity, potential change during repeated use and the like are further improved. These solvents can be used alone or as a mixture of two or more solvents.

The weight ratio of CGM in CGL4 to the binder resin is 100: 1 to 1000 and the film thickness of CGL4 is 0.01 to 10 μm. As a coating method for forming CGL4, a blade is used. There are various coating methods such as coating, wire bar coating, spray coating, dip coating and slide hopper coating.

Next, as the CTM contained in the CTL5, hydrazone compounds, styryl compounds, benzidine compounds, stilbene compounds and the like are used.

The binder resin used in the CTL5 can be appropriately selected from a wide range of insulating resins and used. A preferable binder resin is silicone-
Alkyd resin, phenol-formaldehyde resin,
Insulating resins such as poly-N-vinylcarbazole and polysilane can be mentioned, and these binder resins can be used alone or in combination of two or more kinds.

The compounding ratio of the binder resin and CTM is 1:
It is set to 10 to 500, and preferably 1:20 to 150. The thickness of the CTL 5 is set to 1: 100 μm, and more preferably 5 to 50 μm.

As a coating method, a method similar to that of CGL4 can be used.

An intermediate layer is optionally provided between the organic photoreceptor layer and the conductive layer. Examples of the intermediate layer include vinyl chloride vinyl acetate copolymer, vinyl chloride vinyl acetate / maleic acid copolymer, ethyl cellulose and carboxymethyl cellulose. The resin layer has a thickness of 0.01 to 2 μm, such as a copolymer type or modified type alcohol-soluble polyamide resin.

By using the plastic cylindrical substrate produced by the above-mentioned manufacturing method, the thickness is uniform,
Provided is a photosensitive drum which is excellent in cylindricity and circularity of a transparent cylindrical substrate and has no defocus of image exposure light.

Next, an embodiment of an electrophotographic image forming apparatus (electrophotographic apparatus) using the photosensitive drum of the present invention described with reference to FIGS. 1 to 4 will be described using the color image forming apparatus of FIG. Explain. FIG. 5 is a sectional configuration diagram of a color image forming apparatus showing an embodiment of an electrophotographic apparatus using the photosensitive drum of the present invention.

In the color image forming apparatus as the electrophotographic apparatus of the present embodiment, as described above, the image forming member is a photosensitive drum in which a conductive layer and a photosensitive layer are provided on the outer peripheral surface of a transparent cylindrical substrate. An image exposure means is provided inside the photosensitive drum, and a charger, a developing device, a transfer device, a static eliminator, and an external device.
This is a structure in which an image forming process means such as a cleaning device is arranged.

A cylindrical photosensitive drum 10 which is an image forming body.
Is rotated in the clockwise direction indicated by the arrow in FIG. 1 while being grounded.

A scorotron charger 211 as a charging means
Is used in the image forming process of each color of yellow (Y), magenta (M), cyan (C) and black (K), and is held at a predetermined potential with respect to the above-described organic photoconductor layer of the photoconductor drum 10. The control grid and the corona discharge by the discharge electrode perform a charging action to give a uniform potential to the photosensitive drum 10.

Exposure device 21 as image exposure means for each color
Reference numeral 2 denotes FL (fluorescent substance emission), EL (electroluminescence), PL arranged in the axial direction of the photoconductor drum 10.
(Plasma discharge), LED (light emitting diode) and other linear light exposure elements arranged in an array, or LISA
(Photomagnetic effect optical shutter array), PLZT (transmissive piezoelectric element shutter array), LCS (liquid crystal shutter), and the like. , A selfoc lens as a unity-magnification imaging element is configured as a unit attached to an exposure element holding member that holds an exposure element and a selfoc lens as a unity-magnification imaging element, and The image signal of each color stored in the memory, which is attached to the holding member 220 that holds the exposure device provided internally, is sequentially read from the memory and input to the exposure device 212 for each color as an electric signal. It The emission wavelength of the light emitting element used in this embodiment is 600 to 9
It is in the range of 00 nm.

The developing device 213, which is the developing means for each color,
One-component or two-component developers of yellow (Y), magenta (M), cyan (C), and black (K) are contained, respectively, with a predetermined gap being maintained with respect to the peripheral surface of the photosensitive drum 10. A developing sleeve 213a that rotates in the direction is provided.

The developing device 213 for each of the above-mentioned colors is the charging and exposing device 212 by the above-mentioned scorotron charger 211.
The electrostatic latent image formed on the photosensitive drum 10 by the image exposure by and is reverse-developed in a non-contact state by a non-contact developing method by applying a developing bias voltage.

As the original image, an image read by an image pickup device of an image reading apparatus separate from this apparatus or an image edited by a computer is temporarily stored as an image signal for each color of Y, M, C and K. Store and store in.

At the start of image recording, a photoconductor drive motor (not shown) is rotated to rotate the photoconductor drum 10 in the clockwise direction in FIG. 1, and at the same time, a Y scorotron charger placed on the left side of the photoconductor drum 10. The charging action of 211 starts to apply the potential to the photoconductor drum 10.

After the photosensitive drum 10 is applied with an electric potential, the Y exposure device 212 starts the exposure with the electric signal corresponding to the first color signal, that is, the Y image signal to rotate the cylindrical photosensitive drum 10. By scanning, an electrostatic latent image corresponding to the Y image of the original image is formed on the photosensitive layer on the surface thereof.

The latent image is reversely developed by the Y developing device 213 in a state where the developer on the developing sleeve 213a is not in contact with the latent image, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Then, the photosensitive drum 10 is charged on the yellow (Y) toner image by the charging action of the magenta (M) scorotron charger 211 arranged on the left side of the photosensitive drum 10 and above Y. Exposure is performed by the electric signal corresponding to the second color signal of the M exposure device 212, that is, the M image signal.
Yellow (Y) by non-contact reversal development
A magenta (M) toner image is sequentially superimposed on the toner image.

A cyan (C) scorotron charger 21 disposed on the photosensitive drum 10 by the same process.
Further, the cyan (C) toner image corresponding to the third color signal is generated by the exposure devices 212 for C and C and the developing device 213 for C, and black (K ) Scorotron charger 211, exposure device 2
12 and the developing device 213 sequentially form a black (K) toner image corresponding to the fourth color signal,
A color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10.

These Y, M, C and K exposure devices 212
The exposure of the organic photosensitive layer of the photoconductor drum 10 is performed through the transparent substrate described above from the inside of the drum.
Therefore, the exposure of the images corresponding to the second, third, and fourth color signals is performed without any influence from the previously formed toner image, and the same exposure as the image corresponding to the first color signal is performed. It is possible to form an electrostatic latent image.

The developing device 213 uses a contact roller (not shown) and the photosensitive drum 10 and a predetermined value, for example, 100 μm to 1
The developing sleeve 213 is held in a non-contact state with a gap of 000 μm, and the developing sleeve 2 is used for the developing action of the developing device 213 for each color.
A developing bias in which a direct current or an alternating current is applied to 13a is applied, jumping development is performed by a one-component or two-component developer accommodated in the developing device, and the transparent conductive layer is grounded to the photosensitive drum 10. Non-contact reversal development is performed in which a DC bias having the same polarity as that of the toner is applied to attach the toner to the exposed portion.

The transfer sheet P, which is the transfer material, is sent out from the paper feed cassette 215, which is the transfer material storage means, and is conveyed to the timing roller 216. The color toner image formed on the peripheral surface of the photoconductor drum 10 is a transfer material that is fed in synchronization with the toner image on the photoconductor drum 10 by driving the timing roller 216 in the transfer device 214a. It is transferred to the transfer paper P.

The transfer paper P on which the toner image has been transferred is separated from the peripheral surface of the photoconductor by removing the charge in the static eliminator 214b, and is then transferred to the fixing device 217 by the transfer belt 214e which is a transfer unit. . After being heated and pressed by the fixing device 217 to fuse and fix the toner on the transfer paper P, the toner is discharged from the fixing device 217, conveyed by a pair of discharge conveyance rollers 218 a, and discharged onto a tray at the top of the apparatus via the discharge rollers 218. Is discharged with the toner image surface facing down.

On the other hand, the photosensitive drum 10 from which the transfer paper is separated
In the cleaning device 219, the surface of the photoconductor drum 7 is rubbed by the cleaning blade 219a to remove the residual toner and cleaned, and the toner image of the original image is continuously formed, or the toner image of a new original image is temporarily stopped. Formation. The waste toner scraped off by the cleaning blade 219a and the cleaning roller 219b is discharged to a waste toner container (not shown) by the toner conveying screw 219c.

By using the photosensitive drum of the present invention in which the cylindricity, roundness, wall thickness and the like of the inner and outer peripheral surfaces are molded with high precision, good electrophotography free from image blur due to defocus of image exposure light. A color image forming apparatus as an apparatus is provided.

[0054]

According to the first aspect of the present invention, the plastic cylindrical substrate is a transparent substrate having a light transmittance of 90%, has a strength comparable to that of aluminum, and has an impact resistance performance 15 times that of glass. It has a roundness accuracy of about 30 μm.
In addition, compared to the extrusion method, which is a widely used molding method, no die scratches are left on the surface of the cylindrical substrate, and in particular, the surface is formed on a natural surface obtained by centrifugal force and has a smooth surface such as a glass surface. A surface is formed. Moreover, it is stronger than the cylindrical substrate obtained by the extrusion method and is excellent in the stable mechanical strength with no directionality and the heat distortion temperature. The photosensitive drum using the cylindrical substrate is a transparent cylinder. The cylindricity and circularity of the cylindrical substrate are molded with high precision on both the inner and outer peripheral surfaces, and there is no defocus of the image exposure light, and image blurring is prevented.

According to the second aspect, in particular, the inner peripheral surface of the cylindrical substrate is not scratched, and the smooth surface is formed.

According to the third aspect of the present invention, by using the photoconductor drum of the present invention in which the cylindricity, the roundness, the wall thickness, etc. of the inner and outer peripheral surfaces are molded with high precision, an image due to defocus of the image exposure light is used. A color image forming apparatus as an excellent electrophotographic apparatus without blurring is provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing steps of a method for manufacturing a cylindrical substrate for a photosensitive drum of the present invention.

FIG. 2 is a sectional view showing an embodiment of a molding die for manufacturing a cylindrical substrate.

FIG. 3 is a side sectional view of FIG. 2;

FIG. 4 is a cross-sectional view showing an example of the configuration of a photosensitive drum of the present invention.

FIG. 5 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of an electrophotographic apparatus using a photosensitive drum of the present invention.

FIG. 6 is a view showing a mold for molding a plastic cylindrical substrate under consideration by the present inventors.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical substrate 2 Conductive layer 3 Organic photoconductor layer 10 Photoconductor drum 100 Mold 110 Steam chamber 111 Mold 112a, 112b Side plate 113 Center shaft 114a, 114b Arm 115 Roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Hama ▼ Shuta Ta, 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock company (72) Inventor Toshihide Miura 5-14-14 Midori-cho, Koganei-shi, Tokyo

Claims (3)

[Claims] 1. A photosensitive drum having a transparent cylindrical substrate and a photosensitive layer provided on an outer peripheral surface of the cylindrical substrate, wherein the cylindrical substrate is a polymerizable liquid in a cylindrical mold. A photosensitive drum, wherein the inner peripheral surface is molded by a roller when the material is injected and the polymerizable liquid material is polymerized while rotating the cylindrical mold. 2. The photosensitive drum according to claim 1, wherein the roller is driven at a peripheral speed of the roller that is the same as the peripheral speed of the inner surface of the cylindrical substrate. 3. A photosensitive drum having a transparent cylindrical substrate and a photosensitive layer provided on an outer peripheral surface of the cylindrical substrate, wherein the cylindrical substrate is a polymerizable liquid in a cylindrical mold. When injecting a material and polymerizing the polymerizable liquid material while rotating the mold, the inner peripheral surface is molded by a roller,
The peripheral speed of the roller is the same as the peripheral speed of the inner surface of the cylindrical substrate, and a photosensitive drum manufactured by driving the roller and the photosensitive drum provided inside the photosensitive drum are provided. An electrophotographic apparatus, comprising: an image exposing unit for exposing.