JPH09138519A - Electrophotgraphic photoreceptor and method and device for forming image using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic photoreceptor preventing image blurring from occurring because the deformation of a base substance is extremely little by setting the thermal deformation start temperature of the transparent base substance equal to or above a specified value, and a method and a device for forming an image in which the photoreceptor is used. SOLUTION: This electrophotographic photoreceptor 10 is provided with a photoreceptive layer on the cylindrical transparent base substance. In the case the organic photoreceptive layer is applied at the time of producing the photoreceptor, it must be heated to be dried, so that the base substance itself is somewhat deformed and dimensional accuracy is lowered. It is the factor of image blurring and irregular density at the time of forming the image. Even when in-machine temperature rises because of heating at the time of producing the photoreceptor or at the time of performing consecutive printing for a long time, it does not matter in practical use by setting the thermal deformation start temperature of the transparent base substance to >=90 deg.C. The composition of resin to be used is, for example, polyolefin or polycarbonate. In this method and this device; the image is formed by using the photoreceptor 10, performing image exposure from the inner surface side of the photoreceptor and developing the image in non-contact state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used for image formation in copying machines, printers, etc., an image forming method using the same, and an image forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic method,
Attention has been focused on a type in which light is exposed from the inner surface of the photoconductor through a cylindrical transparent substrate. This is because it is considered to be the best configuration at present in order to satisfy the recent user needs that high-quality color images can be obtained at high speed and that it must be compact in order to save space in the office. .

However, when exposing from the inner surface of the photoreceptor, a transparent photoreceptor substrate having a large diameter capable of accommodating the exposure device is required. Conventionally, metals such as aluminum, steel, copper, and nickel, and nonmetals such as paper and plastic have been used as the base of electrophotographic photoreceptors, and the cylindrical base has easy grounding and dimensional stability. In view of the above, the present situation is that aluminum is mainly used as the substrate.

However, aluminum has a drawback in that it has high physical distribution costs, cutting and surface polishing costs, and poor workability. In consideration of this point, it has been proposed to use a resin, such as plastic, which is low cost, lightweight and excellent in workability, formed in a cylindrical shape as a base body of a photoreceptor.

On the other hand, when exposing from the inner surface of the photoreceptor, it is necessary to use a transparent substrate. As a typical transparent material, for example, when glass is used as the substrate material, its productivity and accuracy are improved. Besides, there are problems in lightness, cost, and impact resistance, and it seems difficult to put it into practical use.

[0006] Therefore, the applicant of the present invention was previously disclosed in Japanese Patent Application No. 7-
In No. 13983, a method for producing a transparent and highly accurate substrate using a synthetic resin that is lightweight, has excellent impact resistance, and is low in cost was proposed.

However, the resin used in the above-mentioned Japanese Patent Application has a problem in heat resistance and may be deformed due to heat applied during drying when coating the intermediate layer or the photosensitive layer, resulting in deterioration of dimensional accuracy. I understood. Especially when the non-contact development method is used, accuracy of the deflection and straightness of the substrate is required.
However, it is difficult to adopt a resin-based substrate.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an electrophotographic photosensitive member having an exposure device housed therein, which may be heated for drying during coating of the photosensitive layer or continuously image-formed for a long time. The object of the present invention is to provide an electrophotographic photosensitive member having a substrate with very little deformation and causing no image blurring, and an image forming method and apparatus using the same.

[0009]

The object of the present invention is attained by adopting one of the following constitutions.

[1] An electrophotographic photosensitive member comprising a cylindrical transparent substrate provided with a photosensitive layer, wherein the transparent substrate has a thermal deformation starting temperature of 90 ° C. or higher.

[2] A method for forming a large number of images by repeating the steps of imagewise exposure, development, transfer, separation, fixing and cleaning by uniformly charging the surface of a cylindrical electrophotographic photosensitive member. An image forming method, which comprises using the electrophotographic photoreceptor described above, performing image exposure from the inner surface of the photoreceptor, and forming an image by non-contact development.

[3] In an image forming apparatus for forming a large number of images having a cylindrical electrophotographic photosensitive member, a mechanism of uniform charging, image exposure, development, transfer, separation, fixing and cleaning, [1] An image forming apparatus, which uses the electrophotographic photoreceptor described above, performs image exposure from the inner surface of the photoreceptor, and forms an image by non-contact development.

As described above, Japanese Patent Application No. 7-13983 proposes a method of manufacturing a transparent and highly accurate substrate using a synthetic resin which is lightweight, has excellent impact resistance, and is low in cost.

Although a methacrylic acid ester resin or the like is used as the resin, it has been examined by the present inventors that, when an organic photosensitive layer or the like is applied at the time of manufacturing a photoreceptor, heat must be applied for drying and the substrate itself It deforms a little and the dimensional accuracy decreases.
This causes image blurring and density unevenness at the time of image formation, and particularly when using the non-contact developing method, accuracy of the deflection and straightness of the substrate is required, but it has been found that the requirements cannot be satisfied. did.

The thermal deformation start temperature in the present invention is AS
In TM standard (or JIS standard based on this),
Deflection temperature under load (HDT) when a load of 18.6 kgf / cm ² is applied. This is an industrial index based on physical heat resistance. As shown in FIG. 1, a load of 18.6 kgf / cm ² is applied to a test piece by a three-point load in a heating bath, and the temperature is increased at 2 ° C./min. Raise. Since the mechanical strength decreases as the temperature rises, the test piece gradually bends, but this displacement is the temperature at which it reaches 0.254 mm.
It may also be called the heat distortion temperature or the heat distortion temperature.

Reference numeral 1 is a weight, 2 is a dial gauge, 3 is a load bar, 4 is a test piece, 5 is a metal frame, 6 is a thermometer, 7 is a stirrer, and 8 is an electrothermal oil tank. The unit of the entered numbers is mm.

In the examination of the present invention, if the thermal deformation starting temperature is 90 ° C. or higher, heating occurs when the intermediate layer or the photosensitive layer is applied to the surface of the photoconductor substrate, or the temperature inside the machine rises during continuous printing for a long time. However, I found that there was no problem in practical use. It can be said that the higher one is good for practical use as many times as possible, and the higher one is preferable, but the heat deformation start temperature of many resins is 2
In view of matters other than the present invention, such as easiness of molding process of the material, it is not necessarily said that the higher the temperature is, the better, and it is preferable that the temperature does not exceed 200 ° C. Compositionally, for example, polyolefins, polycarbonates, non-quality polyamides, polysulfones, polyether sulfones, polymethylpentene, crosslinked acrylics and the like can be mentioned.

In the present invention, "transparent" means that the image exposure light of the photoconductor is transmitted by 50% or more, preferably 80% or more.

Next, the case where the transparent cylindrical substrate is used as the photoreceptor will be described.

A typical example is an electrophotographic photosensitive member having a conductive layer and a photoconductive photosensitive layer provided on the surface of a cylindrical substrate, which has been conventionally used for providing the conductive layer and the photoconductive photosensitive layer. The method can be widely used.

That is, the transparent conductive layer is formed by vapor deposition or sputtering of a metal or metal oxide such as aluminum or ITO (indium tin oxide), or a mixture of ITO or alumina conductive fine particles and resin. A typical example thereof is the formation of a coating film of a conductive resin with a material.

When the intermediate layer is provided, a resin type intermediate layer using a polyamide type compound such as nylon, or a so-called ceramic type intermediate layer using an organometallic compound and / or a silane coupling agent (also referred to as a hardening type intermediate layer). Say)
Is preferably used.

In forming the photosensitive layer, an inorganic photoconductor layer may be formed by vapor deposition or the like, but an organic photoconductor layer, particularly a function separation type containing both a charge transporting substance and a charge generating substance, particularly each It is desirable to form an organic photoconductor of the type in which the above are separately laminated.

The charge generation layer is formed by dispersing a charge generation material (CGM) in a binder resin as needed. Examples of CGM include metal or metal-free phthalocyanine compounds, azo compounds such as bisazo compounds and trisazo compounds, squarium compounds, azurenium compounds, perylene compounds, indico compounds, quinacridone compounds, polycyclic quinone compounds, cyanine dyes, xanthene dyes, Examples include, but are not limited to, charge transfer complexes comprising poly-N-vinylcarbazole and trinitrofluorenone. These may be used as a mixture of two or more as necessary. However, in order to achieve the object of the present invention at the highest level, one of perylene compounds, one of imidazole perylene compounds and one of metal phthalocyanine compounds, titanyl phthalocyanine (TiOP
c) is preferred.

Examples of the binder resin usable in the charge generation layer include polystyrene resin, polyethylene resin, polypropylene resin, polyacrylic resin, polymethacryl resin, polyvinyl chloride resin, polyvinyl acetate resin, polyvinyl butyral resin, and poly (vinyl butyral) resin. Epoxy resin, polyurethane resin, polyphenol resin, polyester resin, polyalkyd resin, polycarbonate resin, polysilicone resin, polymelamine resin, and copolymer resin containing two or more of the repeating units of these resins, for example, vinyl chloride-acetic acid. Vinyl copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and high molecular organic semiconductors such as poly-N-vinylcarbazole,
And the like, but are not limited thereto. Among the above, as a preferred binder when an imidazole perylene compound is used as CGM, a polyvinyl butyral resin is used. As a preferred binder when using TiOPc, a polysilicone resin and a polyvinyl butyral resin, or a mixture of both are used. No.

The charge transport layer is composed of a charge transport material (CTM) alone or together with a binder resin.
Examples of the CTM include a carbazole derivative, an oxazole derivative, an oxadiazole derivative, a thiazole derivative, a thiadiazole derivative, a triazole derivative, an imidazole derivative, an imidazolone derivative, an imidazolidine derivative, a bisimidazolidine derivative, a styryl compound,
Hydrazone compounds, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives,
Benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives,
Examples include, but are not limited to, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, and the like. These may be used alone or in combination of two or more.

Examples of the binder resin usable in the charge transport layer include polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin,
Examples thereof include, but are not limited to, styrene-acrylonitrile copolymer resin, polymethacrylate resin, and styrene-methacrylate copolymer resin.

Further, in order to reduce fatigue deterioration after repeated use or to improve durability, conventionally known antioxidants, ultraviolet absorbers, electron accepting substances, surfaces may be used in any of the layers of the photoreceptor. A modifier, a plasticizer, and the like, an environment-dependent reducing agent, and the like can be added in an appropriate amount, if necessary.

If desired, a non-photosensitive layer such as a protective layer may be provided in addition to the photosensitive layer in order to improve durability.

For the substrate, more preferable physical properties can be realized by using a cross-linking agent, a conductivity-imparting agent, a colorant and the like mixed with the polymerizable liquid material for the photoreceptor substrate. For example, the addition of a cross-linking agent improves heat resistance, solvent resistance, and strength, and the conductivity-imparting agent can prevent electrostatic contamination such as dust and replace the conductive layer. These are effective for photoconductors that are subjected to external force or heat during use or coated with a solution on a substrate.

Next, an embodiment of the image forming apparatus of the present invention will be described.
The color image forming apparatus of FIG. 2 will be described. FIG.
FIG. 3 is a cross-sectional configuration diagram of a color image forming apparatus showing an example of an image forming apparatus to which the electrophotographic photosensitive member manufactured using the cylindrical substrate of the present invention described above is applied.

The image forming apparatus of the present invention is mechanically, at least in the case of image formation for the second and subsequent colors, non-contact development (the latent image formed on the surface of the photoconductor and the developer layer on the developing sleeve do not come into contact with each other in the developing area). It is necessary to carry out the development method under the conditions). In this case, it is necessary to accurately set a condition in which the two do not come into contact with each other but do not separate too much, and the dimensional accuracy of the photoconductor substrate is more strictly required.

Reference numeral 10 denotes a drum-shaped photoreceptor, which is a function-separated organic photosensitive layer having a transparent conductive layer, a charge generation layer and a charge transfer layer on the outer periphery of a cylindrical substrate formed of a highly transparent polymer resin. Is formed. 110Y, 110
M, 110C and 110K are scorotron corona charging devices used in the image forming process of each color of yellow (Y), magenta (M), cyan (C) and black (K), and are the above-mentioned organic photosensitive layers of the photoconductor 10. On the other hand, in order to hold the electric charge of a predetermined potential, a charging action is performed by corona discharge, and a uniform potential is given to the photoconductor 10.

12Y, 12M, 12C and 12K are
FL (phosphor emission), EL (electroluminescence), PL (plasma discharge), LED (light emitting diode), and lamp and optical shutter functions in which light emitting elements arranged in the axial direction of the photoconductor 10 are arranged in a line in an array. LISA (Opto-Magnetic Effect Optical Shutter Array) in which elements with
PLZT (transmissive piezoelectric element shutter array), LCS
An image of each color read by a separate image reading device with an exposure optical system that is an image exposure device configured as a unit with an exposure element such as a (liquid crystal shutter) and a SELFOC lens as a unity-magnification imaging element. The signals are sequentially taken out from the memory and the exposure optical systems 12Y, 12M, 1
It is input as an electric signal to 2C and 12K, respectively. The exposure optical systems 12Y, 12M, 12C and 1
Each of the 2K is attached to a cylindrical holding member 20 and accommodated inside the base of the photoconductor 10.

13Y, 13M, 13C and 13K are developing devices which are non-contact developing devices for accommodating yellow (Y), magenta (M), cyan (C) and black (K) developers. The developing sleeve 1 rotates in the same direction with a predetermined gap from the peripheral surface of the photoconductor 10.
30Y, 130M, 130C and 130K.

The developing devices 13Y, 13M, 13C and 13K are the corona charging devices 110Y and 110 described above.
Optical system 1 for charging and exposing by M, 110C and 110K
The electrostatic latent image formed on the photoconductor 10 by image exposure with 2Y, 12M, 12C and 12K is reversely developed in a non-contact state by applying a developing bias voltage.

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

When the image recording is started, the photoconductor driving motor is started to rotate the photoconductor 10 in the clockwise direction, and at the same time, the photoconductor 10 is charged by the corona charging device 110Y.
Application of electric potential is started.

After a potential is applied to the photoconductor 10, the exposure optical system 12Y starts exposure by an electric signal corresponding to a first color signal, that is, a yellow (Y) image signal, and the drum is rotationally scanned to expose it. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface.

The latent image is reversal-developed by the developing device 13Y with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Then, the photosensitive drum 10 is further covered with the corona charging device 110M on the yellow (Y) toner image.
Is applied with a potential by the charging action of the exposure optical system 12M, the exposure is performed by an electric signal corresponding to the second color signal of the exposure optical system 12M, that is, the image signal of magenta (M), and the non-contact reverse development by the developing device 13M causes A magenta (M) toner image is sequentially formed on the yellow (Y) toner image.

By the same process, the corona charging device 11
0C, the exposure optical system 12C and the developing device 13C further convert a cyan (C) toner image corresponding to the third color signal into a fourth color signal by the corona charging device 110K, the exposure optical system 12K and the developing device 13K. Corresponding black (K) toner images are sequentially superposed and formed, and a color toner image is formed on the peripheral surface of the photosensitive drum 10 within one rotation.

These exposure optical systems 12Y, 12M, 12C
The exposure of the organic photosensitive layer of the photoconductor drum 10 by (1) and (12K) is performed from the inside of the substrate through the transparent substrate described above. Therefore, the exposure of the image corresponding to the second, third, and fourth color signals is performed without any influence of the toner image previously formed, and is equivalent to the image corresponding to the first color signal. It is possible to form an electrostatic latent image. In order to stabilize the temperature inside the photoconductor drum and prevent the temperature rise due to the heat generated by the exposure optical systems 12Y, 12M, 12C and 12K, a material having good thermal conductivity is used for the holding member 20, and a heater is used at low temperature. In the case of high temperature, it is possible to suppress the heat to the outside by taking measures such as radiating heat to the outside through a heat pipe. Further, during the developing operation by the developing devices 13Y, 13M, 13C and 13K, the developing sleeves 130Y, 130M,
A developing bias in which a direct current or an alternating current is applied to 130C and 130K is applied, and jumping development is performed by a one-component or two-component developer accommodated in the developing device, so that the photoconductor 10 that grounds the transparent conductive layer is grounded. On the other hand, a non-contact reversal development in which a DC bias having the same polarity as that of the toner is applied to attach the toner to the exposed portion is performed.

In this way, the color toner image formed on the peripheral surface of the photosensitive drum is sent from the paper feeding cassette 15 by the sending roller 15a in the transfer device 14a, and is sent to the timing roller 16 by the pair of carrying rollers 15b and 15c. The sheet is conveyed, and is driven by the timing roller 16 to be transferred onto a transfer sheet P that is a transfer material that is fed in synchronization with the toner image on the photoconductor 10.

The transfer paper P on which the toner image has been transferred is separated from the drum peripheral surface by being subjected to the removal of charge in the static eliminator 14b, and then the transport driving roller 14c and the driven roller 14d.
The fixing device 17 is provided by the conveyance belt 14e stretched between
In the fixing device 17, the fixing roller 17 is conveyed to
a, the toner is fused and fixed on the transfer paper P by being heated and pressure-bonded between the pressure roller 17b and the fixing outlet roller pair 17d.
Is discharged from the fixing device 17 by the
8a, and the sheet is discharged onto the sheet discharge tray 200 at the upper part of the apparatus through the sheet discharge roller 18, but the one using the photosensitive drum 10 having the photosensitive layer on the cylindrical substrate of the present invention described above is used. A clear and extremely good image was obtained.

On the other hand, the photoconductor 10 from which the transfer paper is separated is cleaned by the cleaning blade 19a in the cleaning device 19.
Thus, the surface of the photoconductor 10 is rubbed to remove and clean residual toner, and the toner image of the original image is continuously formed or is temporarily stopped to form a new toner image of the original image. The waste toner scraped off by the cleaning blade 19a is removed by the toner transport screw 19b.
It is discharged to a waste toner container (not shown).

Since the photoconductor 10 has the exposure optical system housed therein, even if the diameter of the drum is relatively small,
A plurality of corona charging devices 110 described above are provided on the outer peripheral surface thereof.
Y, 110M, 110C and 110K, developing device 13
Y, 13M, 13C, 13K, etc. can be provided, and the volume of the apparatus can be made compact by using a small-diameter drum having an outer diameter of 30 mm to 150 mm.

[0048]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

1 Production of Cylindrical Transparent Substrate The substrate has a thermal deformation starting temperature and a glass transition temperature (Tg).
Of different materials were processed, and the obtained base body was cut at the ends to obtain a cylindrical base body having an outer diameter of 100 mm and a length of 360 mm. Furthermore, if necessary, the outer peripheral surface was cut with a cutting tool to obtain a cylindrical substrate of the present invention.

[0050]

[Table 1]

The four cylindrical transparent substrates thus obtained are cylindrical substrates having a transmittance for light having a wavelength of 780 nm of 85% or more.

2 Formation of Conductive Layer Conductive paint X-101H10 manufactured by Sumitomo Metal Mining Co., Ltd.
To the conductive layer coating solution diluted with 100 parts by weight of toluene to 0 parts by weight, the above cylindrical transparent substrate was applied by dip coating, followed by heat treatment at 80 ° C. for 30 minutes to give a thickness of 0.5.
A conductive layer of μm was provided.

3 Formation of Photosensitive Layer (Intermediate Layer) A1 Titanium chelate compound TC-750 (Matsumoto Pharmaceutical Co., Ltd.) 20 parts by weight B1 Silane coupling agent KBM-503 (Shin-Etsu Chemical Co., Ltd.) 13 parts by weight 2-propanol 100 parts by weight were mixed to obtain an intermediate layer liquid. This was dip-coated on a cylindrical transparent substrate having the above conductive layer and dried at 100 ° C. for 90 minutes to obtain an intermediate layer having a thickness of 1.0 μm.

(Charge Generation Layer) G1 Y-type titanyl phthalocyanine 4 parts by weight Silicone resin KR-5240 (Shin-Etsu Chemical Co., Ltd.) 45 parts by weight 2-butanone 100 parts by weight are mixed and dispersed in a sand mill for 10 hours to charge. A generating layer coating solution was obtained. This solution was applied onto the undercoat layer by dip coating to obtain a charge generation layer having a thickness of 0.25 μm.

(Charge Transport Layer) T1 charge transport material 8 parts by weight Bisphenol Z-type polycarbonate Z-300 (Mitsubishi Gas Chemical Co., Inc.) 12 parts by weight 1,2-dichloroethane 100 parts by weight are mixed and dissolved to apply the charge transport layer. A liquid was obtained. This solution was applied onto the charge generation layer by dip coating and heat-treated at 95 ° C. for 1 hour to form a charge transport layer having a thickness of 25 μm.

[0056]

Embedded image

4 Evaluation Method and Results The following tests were performed on each of the photoconductors thus produced.

(1) Thermal deformation start temperature (deflection temperature under load)
HDT) It was measured by the method described in the text.

(2) Dimensional Change Amount of change in circularity and straightness (Δμm) when a cylindrical substrate that was self-supported in an oven was heated was taken as the amount of dimensional change.
Heating temperature is 90 ℃, 100 minutes and 120 ℃, 2/100
The condition was processed.

(3) Image Performance Each image bearing member was mounted on the inner side exposure type color image forming apparatus shown in FIG. 2 and image evaluation was performed. The image performance was evaluated by evaluating the printing characteristics. The character image information was applied to the photoconductor by LED exposure, and the quality of the character image formed on the plain paper was evaluated through a regular image forming process.

Display in Table ◯: Image quality is clear Δ: Image blur is slight X: Image blur is conspicuous and clearly unsuitable for practical use (Image blur is not enough resolution of the character image, and the stroke is small in small kanji. Is a state in which it cannot be sufficiently determined.)

[0062]

[Table 2]

As is clear from Table 2, Examples 1 to 3 in the present invention have a high thermal deformation start temperature, a small dimensional change amount, and a small image performance and can be used practically. The examples prove to be problematic in practice.

[0064]

According to the present invention, even when the photosensitive layer is heated when the photosensitive layer is coated by using the photosensitive body substrate in which the exposure device can be housed,
It is possible to provide a photoreceptor in which deformation of a substrate is extremely small and image blurring does not occur, and an image forming method and apparatus using the photoreceptor.

[Brief description of the drawings]

FIG. 1 is a front view (a) and a side view (b) for explaining an apparatus for measuring a thermal deformation starting temperature of the present invention.

FIG. 2 is a sectional configuration diagram of an image forming apparatus of the present invention.

[Explanation of symbols]

10 Photoreceptor (Photoreceptor Drum) 12Y, 12M, 12C, 12K Yellow, Magenta, Cyan, Black Exposure Optical System (Exposure Device) 13Y, 13M, 13C, 13K Yellow, Magenta, Cyan, Black Developing Device 110Y, 110M , 110C, 110K yellow,
Magenta, cyan, and black corona charging device 15 Paper feed cassette 16 Timing roller 17 Fixing device 19 Cleaning device P Transfer paper

Claims (3)

[Claims] 1. An electrophotographic photosensitive member comprising a cylindrical transparent substrate provided with a photosensitive layer, wherein the transparent substrate has a thermal deformation starting temperature of 90 ° C. or higher. 2. A method for forming a multicolor color image by uniformly charging a surface of a cylindrical electrophotographic photosensitive member and repeating the steps of image exposure, development, transfer, separation, fixing and cleaning. An image forming method comprising using the electrophotographic photoconductor of item 1 above, performing image exposure from the surface side of the photoconductor, and forming an image by non-contact development. 3. An image forming apparatus for forming a multicolor image having a cylindrical electrophotographic photosensitive member, uniform charging, image exposure, development, transfer, separation, fixing and cleaning mechanisms. An image forming apparatus, which uses the electrophotographic photosensitive member of 1 above, performs image exposure from the surface side of the photosensitive member, and forms an image by non-contact development.