JPH11174787A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image provided with excellent reproducibility by eliminating an influence of such as miscellaneous light, by the image forming device allowed to perform the image exposing from an inside of the image forming body. SOLUTION: In this image forming device capable of forming the image on the image forming material by performing the electrification, the image exposure and the development, in arranging an electrifying device 11, image exposing means 12 and developing means 13, corresponding to the image forming body 10, the image forming body 10 is constituted of a light transmitting substrate, a light transmitting conductive layer and the high γ photosensitive layer, the image exposing means 12 being arranged inside the image forming body 10, is respectively consisting of exposing element and unmagnification image forming element in a line shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical electrophotographic photosensitive member used for a copying machine, a printer, a facsimile, and the like, and an electrophotographic image forming apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, as one method of forming a multi-color image, charging, image exposure, and development for each color are sequentially performed within one rotation of one photoconductor (electrophotographic photoconductor). 2. Related Art A color image forming apparatus that forms a color image is known.

[0003] However, the above-mentioned color image forming apparatus is capable of forming a high-speed image in a method of forming a multi-color image, but the charging means, image exposing means and developing means within one rotation of the photosensitive member. Need to be installed in multiple sets,
The image exposing means may be stained by toner leaking from the developing means adjacent thereto and impair the image quality. To avoid this, it is necessary to increase the distance between the image exposing means and the developing means. Photoreceptor)
There is a disadvantage that the diameter of the device becomes large and the device becomes large. For the purpose of avoiding this drawback, a photoreceptor layer in which a substrate of an electrophotographic photoreceptor is formed of a translucent material, a plurality of image exposure means are accommodated therein, and an image is formed on the outer periphery of the photoreceptor through the substrate. For example, Japanese Patent Laid-Open No.
No. 307307.

On the other hand, the inventors of the present invention have disclosed a technology in Japanese Patent Application Laid-Open No. Hei 9-114105 for forming an image forming body by molding a substrate of plastic as the above-mentioned cylindrical translucent substrate. .

[0005]

In the image forming apparatus, when the image exposure is performed from the inside of the translucent substrate of the image forming body, excellent features such as the fact that the image exposure means is not contaminated by the toner. On the other hand, there are also problems.

When a transmissive substrate is used for an image forming body, the translucent substrate is insulative, so that it is necessary to provide a translucent conductive layer between the translucent substrate and the photosensitive layer. As a light-transmitting substrate, fine particles of a metal such as ITO (indium tin oxide) and metal oxides are dispersed in a resin and coated. FIG.
(A) schematically shows a state when image exposure is performed from the inside of the light-transmitting substrate. The focus position where the latent image is formed on the image forming body is the interface between the conductive layer and the photosensitive layer.
An image is formed after passing through a μm conductive layer. Since the conductive layer is a layer in which fine metal particles are dispersed in a transparent resin, the exposure light causes light scattering while passing through the conductive layer. At the image exposure position where the image is formed, in addition to the exposure light from the image exposure means, exposure light from the outside or exposure light that has been repeatedly reflected on the surface of a light-transmissive substrate, etc. Where the light intensity distribution as shown in FIG. 10B at the position should be, the light intensity distribution as shown in FIG. Similar results are obtained when the image forming position is shifted by the image exposure means or when the thickness of the light transmitting substrate is uneven.

According to the present invention, an image which is generated when an image is exposed from the inside of a light-transmitting substrate and has a slightly blurred sharpness is restored without being affected by disturbance factors other than the image exposure light. It is an object of the present invention to provide an image forming apparatus in which a stable electrostatic latent image is formed and a good image is stably obtained.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a charging device, an image exposure device, and a developing device on an image forming body, and perform charging, image exposure, and development on the image forming body. In an image forming apparatus for forming an image, the image forming body includes a light-transmitting substrate, a light-transmitting conductive layer, and a high-gamma photosensitive layer,
The image exposing means is provided inside the image forming body, and is achieved by an image forming apparatus comprising a linear exposure element and a 1: 1 image forming element.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an image forming apparatus according to the present invention, an image forming body comprises a light-transmitting substrate, a light-transmitting conductive layer and a high gamma photosensitive layer, and an image exposing means is provided inside the image forming body. The image forming apparatus is characterized in that it is an image exposing means comprising a linear exposure element and an equal-magnification image-forming element.

As the translucent cylindrical substrate of the image forming body (also referred to as an electrophotographic photosensitive member) used in the image forming apparatus according to the present invention, a cylindrical substrate made of plastic is used. Hereinafter, a transparent cylindrical substrate made of plastic and an electrophotographic photosensitive member using the same will be described.

First, a method of manufacturing a light-transmitting cylindrical substrate made of plastic for an electrophotographic photosensitive member according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing steps of a method of manufacturing a cylindrical substrate of an electrophotographic photoreceptor, and FIG. 2 is a cross-sectional view showing one embodiment of the manufacturing apparatus of FIG.

In the manufacturing apparatus shown in FIG. 2, reference numeral 101 denotes a cylindrical portion whose inner surface is polished to form a good and highly accurate cylindrical surface. 1
02 is a right lid, 103 is a left lid, and left and right lids 103 and 10 are shown.
2, the mold 100 is formed by sandwiching the cylindrical portion 101 from the left and right and screwing it with screws 151.
The liquid inside 0 does not leak. 102
b denotes an injection port for injecting the polymerizable liquid material from the injection port 102b. 102c is a thermometer for measuring the temperature inside the mold 100.

Left and right lids 1 sandwiching the cylindrical portion 101 of the mold 100
The shafts 103d and 102d provided on the bearing holders 03 and 102 are sandwiched between bearings B1 and B2 provided on the bearing holder H, and the mold 100 is rotatable.
Mounted on top. Further, the bearing fixing base H on which the mold 100 is mounted is inserted into a steam chamber SC as a heating furnace.

A timing belt TB is hung on a timing pulley TP fixed to the shaft 103d, and the timing belt TB is driven and rotated by driving a drive motor (not shown), and the mold 100 rotates at high speed in response to receiving the bearings B1 and B2. Is done.

[0015] After steam is fed into the steam chamber SC from the intake port SC1 provided in the steam chamber SC to heat and mold the mold 100, the steam is discharged to the exhaust port S1.
It is exhausted from C2. The lower part of the steam chamber SC is filled with warm water, and a part of the mold 100 is immersed in the warm water so that the temperature of the mold 100 is set to be uniform.

After the molding of the cylindrical plastic substrate 1 which is a light-transmitting cylindrical substrate, cold air is sent into the steam chamber SC from the air inlet SC1 together with the extraction of the temperature, and the mold 100 is cooled. Is exhausted from the exhaust port SC2. After the molding, the steam chamber SC is removed, the mold 100 is removed from the bearing fixing base H, and the left and right lids 103 and 1 are removed.
02 is removed, and the translucent cylindrical plastic substrate 1 is taken out.

The molding is performed by a centrifugal polymerization method described below.

In the manufacturing process shown in FIG. 1, first, a polymerizable liquid material, for example, methyl methacrylate monomer is synthesized, and a catalyst is added to rapidly polymerize the monomer to adjust the viscosity to a state of not less than 10 cp and not more than 400 cp. ,
Pour into cylindrical mold 100.

When the viscosity is 10 cp or less, the liquid material is
In the step of injecting into the liquid, the degree of polymerization in the liquid dripping or liquid is low, and it takes a long time to cure, resulting in poor productivity. On the other hand, when the viscosity is 400 cp or more, the viscosity is too high, so that uneven injection occurs and bubbles are hardly removed.

The cylindrical mold 100 has an outer diameter of 50 mm or more and 200 mm or less and a length of 2 mm, together with experimental results when used in an image forming apparatus described later.
It is necessary that the thickness is not less than 00 mm and not more than 2000 mm.

If the outer diameter is 50 mm or less, it is difficult to separate the cylindrical plastic substrate 1 from the mold 100, and the outer diameter is 200m.
If it is more than m, deformation resulting from the difference in the coefficient of thermal expansion between the mold 100 and the cylindrical plastic substrate 1 at the time of peeling is large, and particularly the roundness is deteriorated. When the length is 200 mm or less, the size is insufficient for normal image formation.
Further, when the cylindrical plastic substrate 1 is peeled off, deformation occurs and the uniformity is lost in the length direction, and particularly, the straightness is reduced.

By rotating a driving motor (not shown) to rotate the mold 100 and heating it appropriately, uniform polymerization is promoted. After the completion of the polymerization, an annealing treatment for removing the distortion of the entire cylindrical plastic substrate is performed at the same temperature. After the annealing treatment for a certain period of time, cool air is sent into the steam chamber SC from the inlet SC1 to cool the mold 100, and then exhausted from the outlet SC2 to cool the cylindrical plastic substrate 1 by the cool air.

At this time, cooling by cold air is performed from one side of the mold 100, in this embodiment, from the right side provided with the intake port SC1 shown in FIG. Peeling is gradually performed from the right side to the left side, and the internal stress at the time of peeling is uniformly applied from the right side to the left side, and the surface properties are uniform without unevenness and wrinkles due to internal stress distortion Thus, the cylindrical plastic substrate 1 is cooled and peeled while maintaining high precision roundness.

After the cylindrical plastic substrate 1 is peeled off, the steam chamber SC is removed, the mold 100 is removed from the bearing fixing base H, and the cylindrical plastic substrate 1 is removed from the mold 1.
Take out from 00 and perform buff polishing as a finishing process,
Annealing is performed again if necessary, and the cylindrical plastic substrate 1 used for the electrophotographic photosensitive member (also referred to as an image forming member) is completed.

According to the above-described manufacturing method, the dimensional accuracy such as roundness and straightness is good, the surface property is uniform, and both the cylindricity and the roundness are 1 unit.
A highly accurate translucent cylindrical substrate (cylindrical plastic substrate) having a size of 0 μm to 30 μm is obtained, and the outer peripheral surface of the cylindrical plastic substrate is rotated to 30 μm or less when rotated. Although the rotational runout of the image forming body when used in the process is suppressed to a very small level, as shown by the dotted line in FIG. be able to.

In the above-mentioned production, when a functional monomer or a crosslinking agent is added as necessary and the composition is cured by heat, the heat resistance and the solvent resistance are further improved, and the solvent and the solvent used for coating and drying the photosensitive layer are reduced. Deterioration of dimensional accuracy due to the influence of heat can be further reduced.

The light-transmitting cylindrical plastic substrate obtained by such a manufacturing process has no internal distortion, a hardness comparable to aluminum, a light transmittance of 90% or more, and an impact resistance of about 15 times that of glass. Is obtained.

The above-mentioned centrifugal polymerization method does not leave a die scratch on the surface of the cylindrical plastic substrate, and the inner surface is particularly natural, obtained by centrifugal force, as compared with the extrusion method which is a molding method widely used at present. Formed on a surface to form an extremely smooth inner surface such as a glass surface. Moreover, the strength is higher than the cylindrical plastic substrate obtained by the extrusion method,
It has excellent mechanical strength and heat deformation temperature without directionality. Furthermore, since there is no uneven light refraction when light is transmitted from a place where the internal stress is small, it is used as a transparent cylindrical plastic substrate for an image forming body (photoreceptor drum described later), and an image exposure light source is provided therein. Even when applied to an installation type image forming apparatus, image exposure is not distorted and image performance does not deteriorate. Transparency of the cylindrical plastic substrate means that it is transparent to the image exposure light of the image exposure means of the image forming apparatus disposed inside the substrate and performing image exposure.

As the material of the light-transmitting cylindrical plastic substrate molded by centrifugal polymerization, the material obtained by polymerization using a methyl methacrylate monomer as described above is the most light-transmitting material, the strength, the accuracy, the surface property and the like. Although good, other materials such as poly (ethyl methacrylate), poly (butyl methacrylate), poly (ethyl acrylate), poly (butyl acrylate), polystyrene, polyimide, polyester, polyvinyl chloride, and the like, or a copolymer thereof can be used. In the centrifugal polymerization method, since the roundness is determined by the mold used for molding, a highly accurate cylindrical plastic substrate can be obtained. In addition, uneven thickness varies depending on rotation unevenness and viscosity during polymerization and heating conditions during polymerization. Furthermore, polybutylene terephthalate (PBT), polyethylene terephthalate (P
ET), molded products of engineering plastics such as polyphenylene sulfide (PPS) and nylon are used as substitutes for metal materials.

In the above-mentioned centrifugal polymerization method, the conditions for producing the polymerizable liquid material as the material and the outer diameter of the base tube of the cylindrical plastic substrate molded by the inner diameter of the mold 100 are as follows. 50 to 2
And the liquid viscosity of the polymerizable liquid material is 10 to 30.
It is preferable to mold using a polymerizable liquid material of 0 millipascal-second. If the liquid viscosity is lower than 10 millipascal-seconds, the liquid adhering to the upper part of the cylinder of the rotating mold 100 drips or flows downward, and the inner wall is not uniform. If the liquid viscosity is higher than 300 millipascal-seconds, the liquid surface does not change due to non-uniform polymerization of the liquid during rotation, resulting in uneven thickness and uneven thickness. As described above, the accuracy of the outer diameter of the substrate formed by centrifugation is better than the accuracy of the mold, but the accuracy of the inner diameter may be non-uniform.

A photosensitive drum 10 as an electrophotographic photosensitive member (also referred to as an image forming member) shown in the sectional view of FIG.
Is a cylindrical plastic substrate 1 as a transparent plastic cylindrical substrate formed by centrifugal polymerization described in FIG. 1, and a light-transmitting conductive layer 2 formed on the outer peripheral surface of the cylindrical plastic substrate 1. And a photoconductive high gamma photosensitive layer 3 formed on the outer periphery of the conductive layer 2.

As the light-transmitting conductive layer 2, indium tin oxide (ITO), tin oxide, lead oxide, indium oxide,
A transparent conductive resin solution obtained by mixing a resin with conductive fine particles made of alumina, copper iodide, Au, Ag, Ni, Al, or the like is used. As a film forming method, a dip coating method, a spray coating method, or the like is used. Is preferably used. Transparent conductive layer 2
Is preferably between 0.5 and 5 μm.

In order to enhance the translucency of the conductive layer 2, the conductive layer 2
Can be controlled to 600 Å or less in the Rayleigh scattering (scattering by fine particles having a diameter of 1/10 or less of wavelength) region where light scattering due to image exposure hardly occurs. desirable. As the constituent material of the conductive fine particles, it is preferable to use fine particles having a primary particle diameter of 600 angstroms or less and to control the central radius to 100 angstroms or less in addition to the light transmitting property and the dispersion stability of the liquid.

A high gamma photosensitive layer 3 is provided on the upper surface of the conductive layer 2. The high gamma photoreceptor has a light attenuation curve having a shape in which the absolute value of the differential coefficient of the light attenuation curve of the photoreceptor is small when the light amount is small, and sharply increases with an increase in the light amount. The relationship between the exposure amount of the photoreceptor and the potential is shown. At the exposure amount indicated by (LOW), the potential does not decrease and no development is performed. Therefore, there is an advantage that a low-exposure portion due to the influence of scattered light does not occur as a fog on an image. Then, the potential sharply drops at a certain exposure amount or more. Therefore, a binary latent image is formed without an intermediate potential. And FIG.
As shown in (b), the exposure distribution due to defocusing or the like approximated to Gaussian in the dot exposure can be obtained by using the high gamma photoreceptor to have “rising” and “cutting off” light energy distributions that adversely affect image formation. A sharp dot latent image can be obtained by cutting the bottom of the curve.

The high gamma photoreceptor used in the present invention is
The light decay curve of the photoconductive semiconductor of the photoreceptor reduces the charged potential by 1 /
When the light sensitivity at the position attenuated to 2 is E1 / 2 and the light sensitivity at the position where the potential is attenuated to 9/10 at the beginning of exposure is E9 / 10, 1 <(E1 / 2) / (E9 / 10) Particularly preferably, a photoconductive semiconductor which gives a relationship of 2 ≦ (E1 / 2) / (E9 / 10) is selected.

The photosensitivity is defined as the amount of potential decrease (absolute value of differential coefficient) of the photoconductor per minute amount of light when the photoconductor is at a specific potential.

These semiconductor characteristics are found in a photoreceptor which is dispersed and contained as powder particles in a binder resin and is coated on a photoreceptor support as a photosensitive layer.

Examples of the photoconductive semiconductor used in the present invention include JP-B-48-34189 and JP-B-49-433.
No. 8, No. 49-17535, JP-A-47-30328
And phthalocyanine-based photoconductive pigments described in JP-A Nos. 47-30329, 50-38543, and 51-23738.

Specifically, it is a phthalocyanine pigment represented by the general formula (C ₈ H ₄ N ₂ ) Rn, wherein R is a hydrogen atom,
Shooterium, lithium, sodium, potassium,
Copper, silver, beryllium, magnesium, calcium, zinc, cadmium, barium, mercury, aluminum, gallium, indium, lanthanum, neodymium, samarium, europium, cadmium, dysprosium, holmium, erbium, thulium, ytterbium, ruthenium, titanium, tin, Hafnium, lead, thorium, panadium, antimony, chrome, molybdenum, uranium,
Manganese, iron, cobalt, nickel, rhodium, palladium, osmium and platinum, n is 0 to 2,
Among these, metal-free phthalocyanine and copper phthalocyanine of the alpha (α), beta (β), gamma (γ), chi (χ), pie (π) or eprosilon (ε) type are particularly preferred, and the average particle size is more than 0.1. 1 to 0.01 μm
Are preferred.

Next, as the binder resin used for the photoreceptor according to the present invention, for example, styrene resin, acrylic resin,
Vinyl chloride-vinyl acetate copolymer, vinyl acetate-methyl methacrylate copolymer, styrene-butadiene copolymer, vinyl toluene-butadiene copolymer, polycarbonate resin, polyurethane resin, phenol resin, melamine resin, furan resin or epoxy resin And the like, and a phenol resin having a structural unit represented by the following general formula is preferable.

[0041]

Embedded image

In the formula, R and R ₁ are a hydrogen atom or a methyl group,
R ₂ is a hydrogen atom or an epoxy group; R ₃ , R ₄ and R ₅ are a halogen atom, a hydrogen atom, a hydroxy group, a nitro group, a cyano group, an amino group, a carboxy group or a sulfonic acid group or a salt thereof, or a substituent. It is a saturated or unsaturated chain hydrocarbon group having 1 to 3 carbon atoms which may have.

The degree of polymerization of these resins is 2 to 10,000.
And preferably 2 to 100.

Alternatively, the phenolic resin represented by the above general formula is melamine, lignin, chroman, indene, hydrocarbon, polyvinyl alcohol, resin amide, acetate, lactone, acetal, chlorphenol, thiophene or styrenated phenol. Alternatively, those modified with these monomers can also be used effectively (JP-A-54-123535, etc.).

The photoreceptor according to the present invention comprises the photoconductive fine powder and resin, if necessary, rose bengal, auramine, bromophenol blue, bromthymol blue,
Sensitizing charges such as fukuzin and other sensitizers
4,7-trinitro-9-fluorenone, 2,4,5
7-Tetranitro-fluorenone is added to an organic solvent such as benzene, toluene, xylene, trichloroethylene, ethyl acetate, acetone, and methyl ethyl ketone, for example, 100 parts of photoconductive powder, 1-1000 parts of resin, and sensitizing dye 0.0
A photosensitive layer paint is prepared by mixing and dispersing the photosensitive layer paint at a ratio of 5 to 10 parts and an organic solvent of 50 to 5000 parts, and the photosensitive layer paint is dried on the conductive layer 2 to a thickness of 10 to 50 μm. It is manufactured by coating and drying to provide a photosensitive layer. If necessary, an intermediate layer such as an organic polymer compound or a rectifying semiconductor layer can be provided.

In the photosensitive layer, in order to reduce fatigue deterioration when repeatedly used or to improve durability, conventionally known antioxidants, ultraviolet absorbers, electron-accepting substances, surface modifiers An appropriate amount of an environment-dependent reducing agent such as a plasticizer or the like can be added as necessary.

Further, in order to improve the durability, a non-photosensitive layer such as an intermediate layer or a protective layer may be provided in addition to the photosensitive layer, if necessary. Typical examples of the intermediate layer include a resin-based intermediate layer such as a polyamide resin and a so-called ceramic-based intermediate layer formed of an organic metal compound and a silane coupling agent.

Next, an image forming process and configuration of an embodiment of the color image forming apparatus of the present invention will be described with reference to FIGS. FIG. 5 is a cross-sectional configuration diagram of the color image forming apparatus, FIG. 6 is a front cross-sectional view illustrating a support structure of the photosensitive drum, and FIG. 7 is a side cross-sectional view illustrating the support structure of the photosensitive drum. .

Photosensitive drum 1 as a drum-shaped image forming body
Numeral 0 indicates that a cylindrical transparent resin substrate formed of a transparent resin member is provided on the inner side as described above, and a transparent conductive layer and a high gamma photosensitive layer are formed on the outer periphery of the substrate. To rotate in the direction shown by the arrow in FIG.

Reference numeral 11 denotes a scorotron charger (hereinafter simply referred to as a charger), which is charged by a grid maintained at a predetermined potential and a (+) corona discharge by a discharge wire with respect to the high gamma photosensitive layer of the photosensitive drum 10. To apply a uniform (+) potential to the photosensitive drum 10.

The n-type photosensitive layer normally used for (−) charging can also be used for (+) charging in backside exposure performed through a transparent substrate. FIG. 8A is an explanatory diagram showing the reason for using the n-type photoconductor with (+) charging. In backside exposure, image exposure forms an image below the photosensitive layer, which is very close to the conductive layer, and generates (+) and (-) charges. Since the surface of the photoconductor carries (+) charges by corona charging, the (+) ions on the surface of the photosensitive layer are erased by the (−) charges by backside exposure. When (+) charging is performed, ozone generation is small, and the photoreceptor tends to be less deteriorated.
When the image exposure light reaches the surface of the photosensitive layer, the charge polarity of the conventional photosensitive member can be used. FIG. 8B is an explanatory diagram showing a case where the photosensitive member is used by charging (+) using the same charge polarity as in the conventional image exposure from the photosensitive member surface side. Since the photoreceptor using zinc oxide is n-type, the method shown in FIG. 8A is preferably used, and the photoreceptor using phthalocyanine is p-type, so the method shown in FIG. 8B is preferably used. Of course, phthalocyanine can be used in the manner shown in FIG. 8A (negative charging).

Reference numeral 12 denotes an image exposure means, that is, the photosensitive drum 1
An exposure optical system including an LED arrayed in the 0 axis direction and a selfoc lens which is an equal-magnification image forming system. Image signals of respective colors read by a separate image reading device are sequentially taken out from a memory. Each of the exposure optical systems 12 is input as an electric signal, and an image is recorded in which gradation is expressed by pulse width modulation in the sub-scanning direction.
Since the pulse width modulation is a binary exposure compared to the intensity modulation, a stable latent image is formed. In particular, a latent image having high sharpness is formed in combination with the use of the high gamma photoreceptor.

Each of the exposure optical systems 12 is attached to a support member 20 provided as an optical system support means, and is housed inside the substrate of the photosensitive drum 10.

Reference numerals 13Y to 13K denote developers for accommodating yellow (Y), magenta (M), cyan (C), and black (K) developers, each having a predetermined gap with respect to the peripheral surface of the photosensitive drum 10. And a developing sleeve 130 that rotates in the same direction while maintaining the same.

Each of the developing units is in a non-contact state by applying a developing bias voltage to the electrostatic latent image on the photosensitive drum 10 formed by the charging by the charger 11 and the image exposure by the exposure optical system 12. To reverse development.

The original image is temporarily stored in an image reading apparatus separate from the present apparatus as an image read by an image sensor or an image edited by a computer as an image signal for each of Y, M, C and K colors. And stored.

At the start of image recording, the photosensitive drum driving motor starts to rotate the photosensitive drum 10 in a counterclockwise direction, and at the same time, application of a potential to the photosensitive drum 10 is started by the charging action of the charger 11 (Y). You.

After a potential is applied to the photosensitive drum 10, exposure by an electric signal corresponding to a first color signal, that is, an image signal of yellow (Y) is started in the exposure optical system 12 (Y), and the photosensitive drum 10 is driven. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface by rotational scanning.

The latent image is reversal-developed by the developing device 13 (Y) in a state where the developer on the developing sleeve is not in contact, and a yellow (Y) toner image is formed in accordance with the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further provided with a potential on the yellow (Y) toner image by the charging action of the charger 11 (M), and the second color signal of the exposure optical system 12 (M), that is, Exposure is performed with an electric signal corresponding to the magenta (M) image signal, and the magenta (M) toner image is formed on the yellow (Y) toner image by non-contact reversal development by the developing device 13 (M). Are sequentially superimposed and formed.

By the same process, the charger 11 (C),
The exposure optical system 12 (C) and the developing unit 13 (C) further form a cyan (C) toner image corresponding to the third color signal, and the charging unit 11 (K), the exposure optical system 12 (K) and the developing unit 13 (C). A black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed by the unit 13 (K), and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10. You.

The photosensitive drum 1 by each of these exposure optical systems
The exposure of the organic photosensitive layer of No. 0 is performed from the inside of the drum through a substrate transparent to the above-mentioned exposure wavelength. 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. Each exposure optical system 1
In order to stabilize the temperature inside the photosensitive drum 10 and prevent the temperature from rising due to the heat generation of 2, the support member 20 is made of a material having good thermal conductivity, a heater is used at a low temperature, and a heat pipe is used at a high temperature. By taking measures such as dissipating heat to the outside through the device, it can be suppressed to a level that does not cause any trouble.
Further, at the time of the developing action by each developing device, a developing bias to which a direct current or a further alternating current is applied is applied to the developing sleeve 130, and a jumping development is performed by a one-component or two-component developer contained in the developing device, so that the developing sleeve 130 is transparent. Non-contact reversal development is performed on the photosensitive drum 10 that grounds the conductive layer.

FIG. 9 shows a cross-sectional structure of one example of the developing device 13, which is provided so as to face the photosensitive drum 10 which rotates in the direction of the arrow.

Reference numeral 130 denotes a developing sleeve which is made of a non-magnetic conductive material such as aluminum or stainless steel, and whose rotating shaft is fitted into the side wall of the housing 136 and rotates in the direction of the arrow. A voltage is applied to the developing sleeve 130 via a protective resistor 138 by a bias power supply 137 in which a DC power supply and an AC power supply are superimposed.

Reference numeral 131 denotes a magnet body fixed inside the developing sleeve 130 and having a plurality of N and S magnetic poles arranged in the circumferential direction.
The S magnetic pole is usually magnetized to a magnetic flux density of 300 to 1500 Gauss, and forms a spike of developer on the developing sleeve 130 by the magnetic force.

Reference numeral 132 denotes a developer layer thickness regulating member made of a rod-shaped magnetic material for regulating the developer layer thickness on the developing sleeve 130 to a predetermined amount. Reference numeral 133 denotes a developer supply roller which supplies a newly stirred two-component developer onto the developing sleeve. 134 is a developer stirring screw, 135 is a toner replenishing roller, and supplies toner from a toner hopper positioned above to a developer pool in the housing 136.

The toner newly supplied by the toner replenishing roller 135 is stirred with the existing developer by the developer stirring screw 134, and is set to a predetermined charge (Q / M) by frictional charging. After being attached to the surface, the developer is supplied to the developing sleeve 130 by the developer supply roller 133. Developing sleeve 1
A magnetic carrier having toner adhered to the surface by the internal magnet body 131 adheres on the 30 circumferential surface, and rotates in the direction of the arrow. The developer attached to the peripheral surface of the developing sleeve 130 is regulated by the developer layer thickness regulating member 132 such that the layer thickness of the developer becomes a uniform thin layer. The technique for making the layer thickness of the developer on the developing sleeve 130 uniform is described in detail in Japanese Patent Application Laid-Open No. 2-64675 by the present applicant.

With the rotation of the developing sleeve 130, the developer layer regulated to a uniform layer thickness is grounded on the base portion and moves to the developing area facing the photosensitive drum 10. 137, the photosensitive drum 10 and the developing sleeve 1
An oscillating electric field is generated between the photosensitive drum 30 and the toner, so that the toner in the developing area is separated from the carrier by the toner and adheres to the latent image portion on the photosensitive drum 10 to visualize the latent image with toner particles. Development takes place.

By appropriately setting the arrangement relationship of the magnetic poles of the magnet body 131 and the magnetic flux density of the magnetic poles, the developing gap Ds can be reduced.
d can be set, a sufficient developing electric field is maintained,
Further, since the magnetic carrier is also held by the strong magnetic binding force, the toner easily flies in a non-contact state, and a good quality toner image is formed on the latent image portion of the photosensitive drum 10.

The developing device used in the present invention has an excellent feature that a non-contact developing method can easily perform development with a high image density without fogging, but can develop a clear image without fog. Preferred conditions for performing the above are described in more detail below.

Conventionally, a two-component developer composed of a non-magnetic toner having an average particle size of tens of μm and a magnetic carrier having an average particle size of tens to hundreds of μm has been used for the developing device. However, as the developer used in the present invention, the transfer of the toner can be effectively controlled by the oscillating electric field. Therefore, the toner having an average particle diameter of 1 to 20 μm, preferably 4 to 10 μm, and the average particle diameter of 10 to 60 μm, More preferably, 20-50μ
It is preferable to use a two-component developer comprising m carriers. This will be described.

(Carrier) In general, if the average particle size of the magnetic carrier particles is large, the state of the ears of the magnetic brush formed on the developing sleeve 130 becomes coarse, so that the electrostatic latent image is developed while being vibrated by an electric field. However, there is a problem that unevenness tends to appear in the toner image, and the toner density in the ears becomes low, so that high-density development is not performed. In order to solve this problem, the average particle diameter dc of the magnetic carrier particles may be reduced.
It has been found that the above problem does not occur when the thickness is 0 μm, preferably 20 to 50 μm.

When dc is 10 μm or less, it is difficult to sufficiently magnetize the carrier, and the carrier adheres to the surface of the image forming body 1 together with the toner particles, or easily scatters.

When dc is 60 μm or more, the specific surface area of the carrier becomes small, so that the toner cannot be sufficiently charged. Further, since the covering ratio is high, toner scattering is also likely to occur.

The volume average particle diameter dc can be measured by a laser diffraction type particle size distribution analyzer “HEROS” (S
YMPATEC). First, 10 mg of magnetic particles were added together with a surfactant to 50 m of water using a wet disperser.
g and then an ultrasonic homogenizer (output 15
0W), and the value was measured after performing a pretreatment of dispersing for 1 to 10 minutes while taking care not to cause re-aggregation due to heat generation.

The intensity of magnetization of the carrier (maximum magnetization) is 5
-60 emu / g, preferably 10-40 emu / g. Although this strength depends on the magnetic flux density on the developing sleeve 2, under a general magnetic flux density condition of the developing sleeve 130, if it is less than 5 emu / g, the magnetic binding force does not work and causes carrier scattering. . On the other hand, if it exceeds 60 emu / g, the ears of the carrier will be too high, and it will be difficult to maintain a non-contact state with the photosensitive drum 10.

The measurement of the magnetization intensity of the carrier is performed by filling the carrier particles while tapping them into a sample cell of 0.25 cm × 3 cm ² , attaching the sample to a pickup coil, setting the sample in a magnetizer, and setting the DC magnetization characteristics automatically. Recording device "TY
This is performed by causing the XY recorder to draw a hysteresis curve using "PE3257" (manufactured by Yokogawa Hokushin Electric Co., Ltd.).

Such a magnetic carrier is made of a metal such as iron, chromium, nickel, cobalt or the like, or a compound or alloy thereof, such as triiron tetroxide, γ-oxide, as in a conventional magnetic carrier. Ferromagnetic spherical particles such as ferric iron, chromium dioxide, manganese oxide, ferrite, and manganese-copper alloy, or the surfaces of these spherical magnetic particles are made of styrene resin, vinyl resin, ethylene resin. , Rosin-modified resin, acrylic resin, polyamide resin, epoxy resin, polyester resin, silicone resin, fluorine resin, or the like, or by spherical coating with a copolymer.

A so-called resin dispersion type carrier in which magnetic fine particles are dispersed and contained in these resins can also be used.

(Toner) Generally, when the average particle size of the toner particles is reduced, the charge amount is qualitatively reduced in proportion to the square of the particle size, and the adhesive force such as van der Waals force is relatively increased. Scattered easily, and fogging is likely to occur. Then, when the average particle size is 10 μm or less, this problem becomes remarkable. In the developing device of the present invention, this problem is solved by performing the development under an oscillating electric field.

When the volume average particle diameter D ₅₀ (μm) of the toner is large, as already mentioned, the roughness of the image becomes conspicuous. If D ₅₀ is used the toner following micronized 10 [mu] m, the resolution is remarkably improved, so give a clear high-quality images shading difference also faithfully reproduced. D ₅₀ is 20μm or more, results in degradation of image quality, at the 1μm or less, poor charging, scattering and the like easily occurs.

For the above reasons, the volume average particle diameter D _{50 of the} toner
Is 1 to 20 μm, preferably 3 μm ≦ D ₅₀ ≦ 10 μm.

When the D ₅₀ is larger than 10 μm, the particle size is large and the resolution is insufficient. When the D ₅₀ is smaller than 3 μm, the cohesive force is large and the triboelectric charging tends to be poor.

Here, the volume average particle diameter D used for the average particle diameter is
₅₀ is a coulter counter TA-II type (aperture 1
00 μm, manufactured by Coulter Corporation).

Further, since the toner particles follow the electric field, the absolute value of the charge amount of the toner particles is preferably set to 3 to 30 μC / g in the case of a two-component developer, in order to secure the developing property, to prevent fogging and scattering. It is desirable from the viewpoint of prevention. In particular, when the particle size is small, a high charge amount is required.

Examples of the binder resin for such a toner include styrene resin, vinyl resin, ethyl resin, rosin modified resin, acrylic resin, polyamide resin, epoxy resin, polyester resin, and styrene-acryl resin. And the like, or a mixed resin or the like. To these resins, a coloring component such as a color pigment, and if necessary, a charge controlling agent, a release agent such as a wax, etc. are added, and toners such as a conventionally known pulverization granulation method, suspension polymerization method and emulsion polymerization method are used. It can be made by a method equivalent to the manufacturing method.

(Developer) As the two-component developer used in the developing device used in the present invention, the above-described spherical carrier particles and toner are mixed at the same ratio as in the conventional two-component developer. An agent is preferably used. As a carrier, a general coating carrier (density 5 to 5) is used.
8 g / cm ³ ), the toner concentration in the developer is 2 to 30% by weight, preferably 5 to 20% by weight.

If the amount is less than 2% by weight, the number of toners required for development cannot be secured, and the coverage is reduced, resulting in excessive charging and a decrease in developability.

If the content is more than 30% by weight, the coverage becomes large, and poor charging and toner scattering tend to occur.

However, when a relatively light (2-4 g / cm ³ ) resin-dispersed carrier having the above-mentioned density is used as the carrier in the developer, the toner concentration in the developer is as follows:
Slightly higher than when using a general resin-coated carrier,
The content is preferably 5 to 40% by weight, more preferably 10 to 30% by weight.

[0091] If necessary, a fluidizing agent for improving the fluid sliding of particles, a cleaning agent useful for cleaning the surface of the image forming body 1 and the like are mixed with the developer. As the fluidizing agent, colloidal silica, silicon varnish, metal soap or nonionic surfactant can be used. As the cleaning agent, a surfactant such as fatty acid metal salt, organic group-substituted silicon or fluorine can be used. Can be.

The conditions for the developer have been described above. Next, the developing conditions for forming a developer layer with such a developer and developing the electrostatic latent image on the photosensitive drum 10 will be described.

It is preferable that the gap between the developing sleeve 130 and the photosensitive drum 10 is set between 50 and 1,000 μm. If this gap is smaller than 50 μm, it is difficult to form a non-contact developing layer that uniformly performs a developing action, and it is also impossible to supply a sufficient amount of toner to the developing area, so that stable development cannot be performed. Conversely, when the gap exceeds 1,000 μm, the counter electrode effect is reduced, and a sufficient development density cannot be obtained. When the gap is in the range of 50 to 1,000 μm, a non-contact developer layer having an appropriate thickness can be uniformly formed. Therefore, the gap and the thickness of the developer layer are adjusted so that the developer layer does not come into contact with the surface of the photosensitive drum 10 and is as close as possible under the condition that no oscillating electric field is generated during non-image formation. Setting is done. As a result, it is possible to prevent sweeping or fogging from occurring in the toner image. The position where the developing sleeve 130 is close to the photosensitive drum 10 is used to prevent scattering of toner and the like.
A position where the direction of gravity is directed toward the developing sleeve 130 is preferable, but, of course, the position is not limited thereto.
The outer diameter of the developing sleeve 130 is preferably 10 mm to 30 mm, and the rotation speed and the rotation direction of the developing sleeve 130 are changed at a low speed in order to prevent scattering of toner and the like. The direction is preferably opposite to the moving direction, but from the viewpoint of image reproducibility due to the developer layer, it is preferable that the speed is almost the same as or faster in the same direction as the moving direction of the photosensitive drum 10. Therefore, it is preferable that the peripheral speed of the developing sleeve 130 be kept within 1.5 to 3.5 times the peripheral speed of the photosensitive drum 10, and the direction be the same. However, it is not limited to this.

The development under the oscillating electric field is performed by the developing sleeve 13.
The bias power supply 137 applies a superimposed voltage of a DC voltage related to fogging prevention and development density and an AC voltage related to development density and gradation, thereby generating an oscillating electric field in the development area. It is preferred to do so. As the DC component, in the reversal development, the DC component of the bias voltage is set to a voltage substantially equal to the received potential in the non-image background portion of the photosensitive drum 10. The frequency of the AC component is 100 Hz to 20 kHz, preferably 1 to 10 kHz.
Hz and an amplitude of 100 to 5000 V are used.
The AC component is not limited to a sine wave, but may be a rectangular wave, a triangular wave, or the like. If the frequency of the AC component is too low, the pitch of the vibration will appear in the development. Conversely, if it is too high, the developer will not be able to follow the vibration of the electric field, and the development density will decrease, resulting in a clear high image quality. There is a tendency that images cannot be reproduced. The amplitude of the AC component is related to the frequency, but the greater the amplitude, the more the developer layer vibrates, and the more the effect increases.On the other hand, the greater the amplitude, the easier it is to cause fog, Such dielectric breakdown is likely to occur. However, if the carrier particles of the developer are insulated by a resin or the like and are made spherical, the dielectric breakdown can be prevented, and the generation of fog can be prevented by the DC component. The surface of the developing sleeve 130 may be insulated or semi-insulated with a resin or an oxide film,
The surface may be provided with irregularities to improve the transportability of the developer layer. By using the above-mentioned developer and developing conditions, clear development with no fog and excellent resolving power can be performed stably.

The color toner image formed on the peripheral surface of the photosensitive drum 10 is once transferred to the peripheral surface of the intermediate transfer belt 14 provided as an intermediate transfer means.

The intermediate transfer belt 14 has a thickness of 0.5 to 2.0.
mm, a semiconductive substrate of silicon rubber or urethane rubber having a resistance of 10 ⁸ to 10 ¹² Ω · cm, and a thickness of 5 to 50 μm as a toner filming prevention layer on the outside of the rubber substrate. And a two-layer structure with fluorine coating. This layer also preferably has a similar semiconductivity. 0.1-0.5m thickness instead of rubber belt base
m, a semiconductive polyester, polystyrene, polyethylene, polyethylene terephthalate, or the like can also be used. The intermediate transfer belt 14 has rollers 14A, 14B,
The photosensitive drum 10 is stretched between the rollers 14C and 14D and circulated clockwise in synchronization with the peripheral speed of the photosensitive drum 10 by the power transmitted to the roller 14D.

The intermediate transfer belt 14 has a roller 14A.
The belt surface between the roller 14B and the roller 14B is in contact with the peripheral surface of the photosensitive drum 10, while the belt surface on the outer periphery of the roller 14C is in contact with the transfer roller 15, which is a transfer member, to form a toner image transfer area at each contact point. ing.

The color toner image adhered to the peripheral surface of the photosensitive drum 10 first has a polarity opposite to that of the toner applied to the roller 14B at the contact point with the intermediate transfer belt 14 (in the present embodiment, minus). The transfer is sequentially performed on the peripheral surface side of the intermediate transfer belt 14 by applying a bias voltage. That is, the color toner image on the drum is conveyed to the transfer area without scattering the toner by the guidance of the grounded roller 14A, and is efficiently transferred to the intermediate transfer belt 14 side by applying a bias voltage of 1 to 2 kV to the roller 14B. .

On the other hand, the transfer paper P is carried out by the operation of the paper feed roller 17 of a paper feed cassette (not shown) and fed to the timing roller 18, and synchronized with the transport of the color toner image on the intermediate transfer belt 14. The paper is fed to the transfer area of the transfer roller 15.

The transfer roller 15 is connected to the intermediate transfer belt 14.
The transfer paper P fed in the counterclockwise direction is synchronized with the peripheral speed of the intermediate transfer in the transfer area formed by the nip portion between the transfer roller 15 and the roller 14C in the ground state. The color toner images are successively transferred onto the transfer paper P by applying a bias voltage of the opposite polarity to the toner of 1 to 2 kV to the transfer roller 15 in close contact with the color toner image on the belt 14.

The transfer paper P to which the color toner image has been transferred is neutralized, conveyed to the fixing device 91 via the conveyance plate 19, and sandwiched and conveyed between the heat roller 91A and the pressure roller 91B to be heated. After the toner is fused and fixed, the toner is discharged to the outside of the apparatus via a discharge roller 92.

Cleaning devices 100 and 140 are installed on the photosensitive drum 10 and the intermediate transfer belt 14, respectively, and the blades of the cleaning devices 100 and 140 are always in pressure contact with each other. It is kept clean.

To describe the structure, the support member 20 is composed of a pair of front and rear members fixed to the rotation support shaft 30 of the photosensitive drum 10 as shown in FIGS. Both ends of each exposure optical system 12 are adjusted so that the distance to the photosensitive surface is in a predetermined positional relationship via the attaching member 21, and is fixed at the adjustment position by bonding.

On the other hand, the photosensitive drum 10 has flange members 10A and 10B provided at both ends thereof rotatably supported by the support member 20 via bearings B, respectively, and is driven by a gear 10G provided in the flange member 10B. It is rotated about the rotation support shaft 30 in a fixed state as a rotation center.

The rotation support shaft 30 is connected to the photosensitive drum 10
Each of the symmetrical front and rear side plates 40 formed in a U-shape and integrally connected while supporting each of the exposure optical systems 12.
The bearing is supported between.

The side plate 40 is provided with rail members 50 as hanging means at front and rear connecting portions, and the rail members 50 are inserted into and engaged with guide members 60 provided in the apparatus main body to be in a suspended state. By doing so, the rotation support shaft 30, and thus the photosensitive drum 10 and each of the exposure optical systems 12 are placed at substantially predetermined positions.

The image forming apparatus described above is characterized in that an electrostatic latent image with high sharpness is formed without being affected by light other than image exposure light, without causing a focus shift or a defocus. However, after charging, uniform exposure is performed before and after the image exposure, so that the amount of image exposure light can be reduced and a sharp dot latent image with a sharp drop in the peripheral potential of the dot latent image can be obtained. As the light source for uniform exposure used here, in addition to a halogen lamp and a tungsten lamp, for example, a fluorescent lamp or LED used in a transfer-type copying machine can be effectively used. The amount of light for image exposure is usually 0.01% for the phthalocyanine photoreceptor, and the amount of uniform exposure used for
The range is preferably 0.4 to 0.4 times, particularly 0.1 to 0.3 times.

Finally, an example in which a good image is obtained by using the above-described image forming apparatus to produce and use the high gamma photosensitive layer 3 will be specifically described.

(Photoconductor Example 1) Epsilon (ε) type copper phthalocyanine pigment Lionol Blue ER (manufactured by Toyo Ink Co., Ltd.) 1 g Desmorfen 800 (polyester polyol resin manufactured by Nippon Polyurethane) 2 g hexamethylene diisocyanate 2 g 6 g of methyl ethyl ketone The composition according to the above weight ratio was dispersed at room temperature by an ultrasonic disperser for 10 minutes, and dried on a conductive layer 2 in which 3 μm thick ITO was dispersed in a resin using a rotary coating machine. The coating was performed by rotating the coating machine at 800 revolutions per minute so that the thickness became 15 μm. The photosensitive layer of the photoreceptor was dried by heating for about 2 hours in a dryer heated to 160 to 170 ° C.

The photoreceptor thus produced is exposed through a transparent substrate 1 using an LED and a 1: 1 image forming element.
Kawaguchi Electric Co., Ltd. Electrostatic Paper Analyzer (Electrostatic Paper Ana)
(lyzer) SP-428 to measure electrostatic properties. The previously defined photosensitivity ratio obtained here was (E1 / 2) / (E9 / 10) = 8.0. Further, when uniform exposure was accompanied after charging with near-infrared light having an illuminance of 3 lux on the charged sample surface, (E1 / 2) / (E9 / 10) = 2.0. When uniform exposure is performed, the effect of sharpening the latent image is low, but the amount of exposure light required for forming the latent image is small, and the spectral sensitivity is substantially increased. Regarding the charging potentials, both are approximately in the vicinity of -800 V, and no remarkable difference is recognized.

(Photoreceptor Example 2) Alpha (α) type copper phthalocyanine pigment Festogen Blue GP (manufactured by Dainippon Ink and Chemicals, Inc.) 0.33 g Pylon 200 (saturated polyester resin manufactured by Toyobo Co., Ltd.) 2 g Methyl ethyl ketone 8 g After the composition having the above weight ratio was ultrasonically dispersed at room temperature for 15 minutes, the dried film was formed on the conductive layer 2 in which 3 μm thick ITO was dispersed in a resin while rotating the rotary coating machine at 700 rpm. Coating was performed so that the thickness became 15 μm. The photosensitive layer was dried by heating at 80 ° C. for about 10 minutes in a heating dryer to prepare a photosensitive member.

The sensitivity characteristics were as follows: the charging potential was -900 V; the dark decay rate was 20%, and the light sensitivity ratio was (E1 / 2) / (E9 / 10) = 7.0 when compared with the amount of light during the light decay half-life. Was. Further, when uniform exposure was accompanied after charging, (E1 / 2) / (E9 / 10) = 2.0.

(Photoconductor Example 3) Beta (β) type copper phthalocyanine pigment Festogen Blue GNPT (manufactured by Dainippon Ink and Chemicals, Inc.) 0.05 g Panlite (polycarbonate resin manufactured by Teijin Chemicals Ltd.) 1.4 g methylene Since the chloride was charged at 14 g (+), the photoconductive content was reduced as compared with (Photoconductor Examples 1 and 2) so that the image exposure light could sufficiently pass through the photoconductor. The composition according to the above weight ratio at room temperature was 10
After ultrasonic dispersion for about 1 minute, the rotary coating machine was rotated about 800 times on the conductive layer 2 in which ITO having a thickness of 3 μm was dispersed in the resin, and coating was performed so that the film thickness after drying became 20 μm.
The photosensitive layer was dried with hot air at 50 ° C. for 10 minutes to obtain a photosensitive member.

The sensitivity characteristics are as follows: the charging potential is +1100 V, the dark decay rate is 22%, and the light sensitivity ratio is (E1 / 2) / (E9 / 10) = 5.0. Was (E1 / 2) / (E9 / 10) = 2.5.

[0115]

According to the image forming apparatus in which the image exposure is performed from the inside of the image forming body, scattered light and external light other than the image exposure light affect the image forming apparatus in spite of many excellent features. Image tends to be obtained. Conventionally, processing to remove these effects has been performed in the image processing unit.However, the use of the high gamma photoreceptor according to the present invention may cause background fogging when a latent image is formed. As a result, a stable potential pattern having no reproducibility was formed, and in the case of a color image, an image having excellent reproducibility without color smear was obtained.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing a cylindrical substrate.

FIG. 2 is a cross-sectional view showing one embodiment of an apparatus for manufacturing a cylindrical substrate.

FIG. 3 is a cross-sectional view of the photosensitive drum 10.

FIG. 4 is an explanatory diagram showing characteristics of a high gamma photoconductor.

FIG. 5 is a cross-sectional configuration diagram of a color image forming apparatus.

FIG. 6 is a front sectional view showing a support structure of the photosensitive drum.

FIG. 7 is a side sectional view showing a support structure of the photosensitive drum.

FIG. 8 is an explanatory diagram showing a charging mechanism of a photoconductor.

FIG. 9 is a cross-sectional configuration diagram of a developing device.

FIG. 10 is an explanatory diagram of a problem in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate, cylindrical plastic substrate 2 Conductive layer 3 High gamma photosensitive layer 10 Photoconductor drum 11 Charger, scorotron charger 12 Exposure optical system 13 Developing device 130 Developing sleeve 14 Intermediate transfer belt

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 5/14 102 G03G 15/01 Z 15/05 21/00 350 15/01 15/00 115 21/00 350

Claims (5)

[Claims] 1. An image forming apparatus comprising: a charging unit, an image exposing unit, and a developing unit disposed on an image forming body to perform charging, image exposing, and developing to form an image on the image forming body; The formed body is composed of a light-transmitting substrate, a light-transmitting conductive layer, and a high-gamma photosensitive layer, and the image exposing means is disposed inside the image forming body, and includes a linear exposure element and a 1: 1 imaging element. An image forming apparatus comprising: 2. The high-gamma photosensitive layer of the image forming body has a photosensitive member having a shape in which the absolute value of the differential coefficient of the light attenuation curve of the photosensitive member is small when the amount of light is small, and increases sharply as the amount of light increases. The image forming apparatus according to claim 1, wherein the photoconductive semiconductor powder of the photoconductor contains zinc oxide or phthalocyanine, and performs (-) charging. 3. The image forming apparatus according to claim 1, wherein the transparent substrate of the image forming body is a plastic substrate. 4. The image forming apparatus according to claim 1, wherein the conductive layer of the image forming body has conductive fine particles dispersed therein. 5. An image forming apparatus according to claim 1, wherein said image exposure means performs pulse width modulation during image exposure.