JPH06250460A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an image not having a difference in the level of a density caused by transfer memory, to prevent time abrasion of a photosensitive body and to extend the exchange interval of the photosensitive body by specifying the ratio of the circumferential length of an image carrier to that of a recording material carrier. CONSTITUTION:In the image forming device turning an electrostatic latent image formed on the image carrier 1 into a visual image by reversal development and electrostatically transferring the visual image onto a recording material carried on the recording material carrier 5f, to form the image, the ratio of the circumferential length of the image carrier 1 to that of the recording material carrier 5f is set 1:1 and influence by the transfer memory is removed. The image carrier 1 can serve as an organic photoconductor and the photosensitive body incorporating the conductive metallic grain body of <=0.3mum primary grain size or fluororesin on the surface layer of a photosensitive layer on a conductive supporting body, as well. This kind of organic photosensitive body is used to prevent a change in the color balance of a color image caused by dark decay at the time of making the circumferential length of the image carrier 1 the same as that of the recording material carrier 5f.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an electrophotographic type or electrostatic recording type image forming apparatus, and more particularly, for example,
A visible image (toner image) formed on the image carrier by electrostatically attracting and holding the recording material on a recording material carrier such as a dielectric sheet and applying an electric field to the recording material. It is preferably embodied in a color image forming apparatus such as a multicolor electrophotographic copying machine or a color printer that obtains a color image by superposing and transferring on the recording material.

[0002]

2. Description of the Related Art Conventionally, many image forming apparatuses have been proposed to obtain a color image by using, for example, an electrophotographic method.
As one method, a latent image is formed on an electrophotographic photosensitive drum having a photosensitive layer such as OPC (organic photoconductor), Se, and a-Si, which is an image carrier, according to a color separation signal of an original image. Perform development visualization with colored toner, transfer to the recording material carried on the recording material carrier to form a multicolor toner image each time development is performed, and then fix the toner image on the recording material to obtain a color copy. There is an image forming apparatus. FIG. 3 shows an example of such a color image forming apparatus.

In this example, in a color image forming apparatus, a photosensitive drum 1 which is an image bearing member is rotatably supported in the direction of an arrow, and a corona charger 2, an optical system 3 and a developing device are provided around the photosensitive drum 1. 4, a transfer device 5, and a cleaning device 6 are arranged.

The optical system 3 is, for example, a laser beam exposure apparatus which comprises a document scanning section and a color separation filter and irradiates the photosensitive drum 1 with a color-separated light image or a light image E corresponding thereto.

The photosensitive drum 1 uniformly charged by the charger 2 is image-scanned with a light image E for each separated color to form a latent image. The developing device 4 is a rotary developing device,
Four developing devices, that is, a black developing device 4K, a cyan developing device 4C, a magenta developing device 4M, and a yellow developing device 4Y are arranged around the central axis 4b, and a predetermined developing device is provided on the photosensitive drum 1
The latent image on the photosensitive drum 1 is reversely developed by rotating the photosensitive drum 1 to a developing position opposite to, and an image is formed on the photosensitive drum 1 by toner having resin as a base.

Further, the toner image on the photosensitive drum 1 is transferred to the recording material supplied from the recording material cassette 7 via the conveying system and the transfer device 5 to the transfer position facing the photosensitive drum 1. The transfer device 5 includes a transfer drum 5a having a peripheral length corresponding to the maximum recording material length and a transfer corona charger 5 in this example.
b, Adsorption corona charger 5 for electrostatically adsorbing the recording material
a suction roller 5g facing the c, an inner corona charger 5d,
It has an outer corona charger 5e and is driven to rotate. or,
A recording material carrier made of a dielectric sheet, that is, a recording material carrying sheet 5f is integrally stretched in a cylindrical shape in the peripheral opening area of the transfer drum 5a.

As the transfer drum 5a rotates, the toner image on the photosensitive drum 1 is transferred onto the recording material carried on the recording material carrying sheet 5f by the transfer charger 5b.
Is electrostatically transferred with a polarity opposite to the polarity of uniform charging of.

A desired number of color images are transferred to the recording material sucked and conveyed by the recording material carrying sheet 5f to form a full-color image.

When the transfer of the desired number of toner images is completed in this way, the recording material is separated from the transfer drum 5a by the separating means 8 and discharged onto the tray 10 via the heat roller fixing device 9.

On the other hand, after the transfer, the photosensitive drum 1 is subjected to the image forming step again after the residual toner on the surface is cleaned by the cleaning device 6.

[0011]

However, in the above-mentioned conventional apparatus, since the polarity of transfer charging is opposite to the polarity of uniform charging of the photosensitive drum 1, the transfer charged charge is the recording material carrying sheet 5f and the recording material. The photosensitive drum 1 is affected by the influence of the electrostatic latent image, and the uniform charging of the photosensitive drum 1 at the time of forming the next latent image becomes non-uniform. In some cases, so-called “transfer memory” occurs.

In particular, as shown in FIG. 3, when the peripheral length of the photosensitive drum 1 is shorter than the maximum recording material length, the uniform charging of the first round is not affected by the transfer, whereas the second round and thereafter. The uniform charging of No. 1 was affected by the transfer, and a density step called an increase in the density after the second round on the image occurred.

The influence of the reverse polarity transfer as described above is remarkable when the organic photoconductor having the advantage of being safe and inexpensive is used for the photosensitive drum 1.

On the other hand, after transfer, there is an apparatus for charging by arranging a charger for removing the influence of transfer before uniform charging. It is difficult to remove the influence of transfer following the above, and the influence of transfer may appear on the image.

Therefore, an object of the present invention is to obtain an image having no density difference due to a transfer memory, and even when an OPC photosensitive member having a surface protective layer is used as an image bearing member, it is simple. It is an object of the present invention to provide an image forming apparatus that can be used in a configuration, can prevent abrasion of a photoconductor, and can extend the replacement interval of the photoconductor.

[0016]

The above object can be achieved by an image forming apparatus according to the present invention. In summary, the present invention is
An image forming apparatus for forming an image by forming an electrostatic latent image formed on an image bearing member into a visible image by reversal development, and electrostatically transferring this visible image to a recording material carried on a recording material bearing member. In the image forming apparatus, the ratio of the peripheral length of the image carrier to the peripheral length of the recording material carrier is 1: 1. The image carrier can be an organic photoconductor,
The image bearing member may be a photosensitive member containing a conductive metal particle having a primary particle diameter of 0.3 μm or less or a fluorine-based resin in the surface layer of the photosensitive layer on the conductive support.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention will be described below in more detail with reference to the drawings. In the embodiments described below, the present invention is described as being embodied in an electrophotographic color image forming apparatus.

Embodiment 1 In this embodiment, a color image forming apparatus has a digital color image reader section in the upper part and a digital color image printer section in the lower part.

In the reader unit, the original 30 is placed on the original table glass 31 and exposed and scanned by the exposure lamp 32, so that the reflected light image from the original 30 is condensed by the lens 33 on the full-color sensor 34, and color images are obtained. Obtain a decomposed image signal. The color-separated image signal is processed by a video processing unit (not shown) via an amplifier circuit (not shown) and sent to the printer section.

In the printer section, the photosensitive drum 1, which is an image bearing member, is a photosensitive member made of an organic photoconductor, which will be described later, and is rotatably supported in the arrow direction.
Around the area, there are a pre-exposure lamp 11, a corona charger 2, a laser exposure optical system 3, a potential sensor 12, four developing devices 4Y, 4M, 4C and 4K having different colors, and a drum light amount detecting means 1
3, the transfer device 5, and the cleaning device 6 are arranged.

In the laser exposure optical system 3, the image signal from the reader section is converted into an optical signal for image scan exposure by a laser output section (not shown), and the converted laser light is reflected by the polygon mirror 3a. , Is projected onto the surface of the photosensitive drum 1 through the lens 3b and the mirror 3c.

When forming an image on the printer section, the photosensitive drum 1
Is rotated in the direction of the arrow, and the photosensitive drum 1 after the charge is removed by the pre-exposure lamp 11 is uniformly negatively charged by the charger 2, and the light image E is emitted for each separated color to form a latent image. .

Next, a predetermined developing device is operated to reversely develop the latent image on the photosensitive drum 1 to form a toner image on the photosensitive drum 1 with a negative toner made of resin as a base. The developing device selectively approaches the photosensitive drum 1 in accordance with each separated color by the operation of the eccentric cams 24Y, 24M, 24C, and 24K to perform development.

Further, the toner image on the photosensitive drum 1 is
The recording material is transferred from the recording material cassette 7 (7a, 7b, 7c) to the recording material supplied to the transfer position facing the photosensitive drum 1 via the transport system and the transfer device 5. In this embodiment, the transfer device 5 includes a transfer drum 5a having a peripheral length corresponding to the maximum recording material length, a transfer charging device 5b, an adsorption charging device 5c for electrostatically adsorbing the recording material, and a suction roller 5g facing the suction charging device 5c. It has an inner charger 5d and an outer charger 5e. Further, the transfer drum 5a, which is rotatably driven, has a cylindrical recording material carrier 5f integrally stretched in an opening area of its peripheral surface. As the recording material carrier 5f, a dielectric sheet such as a polycarbonate film is used.

As the transfer device 5, that is, the transfer drum 5a is rotated, the toner image on the photosensitive drum is transferred to the recording material carrier, that is, the recording material carrier sheet 5f by the transfer charger 5b.
The image is transferred onto the recording material carried by the recording medium. In this way
A desired number of color images are transferred to the recording material that is adsorbed and conveyed to the recording material carrying sheet 5f, and a full-color image is formed.

In the case of forming a full-color image, when the transfer of the four color toner images is completed in this way, the recording material is separated from the transfer drum 5a by the action of the separating claw 8a, the separating push-up roller 8b and the separating charger 5h, Heat roller fixing device 9
The sheet is discharged to the tray 10 via the.

On the other hand, after the transfer, the photosensitive drum 1 is subjected to the image forming process again after the residual toner on the surface is cleaned by the cleaning device 6.

When images are formed on both sides of the recording material,
Immediately after the fixing device 9 is discharged, the transport path switching guide 19 is driven, and after being guided to the reversing path 21a through the transport vertical path 20, the reverse end of the reversing roller 21b causes the trailing end when fed to the beginning. Then, it is withdrawn in the direction opposite to the direction in which it was fed and is stored in the intermediate tray 22. After that, an image is formed on the other surface by the above-described image forming step.

Further, in order to prevent the scattering of powder on the recording material carrying sheet 5f of the transfer drum 5a and the adhesion of oil on the recording material, the fur brush 14 and the recording material carrying sheet 5 are prevented.
The backup brush 15 facing the brush 14 via f, the oil removing roller 16 and the recording material carrying sheet 5f
Backup brush 1 facing the roller 16 through
Cleaning is performed by the action of 7. Such cleaning is performed before or after image formation, and at any time when a jam (paper jam) occurs.

Further, in this embodiment, the eccentric cam 25 is operated at a desired timing and the cam follower 5i integrated with the transfer drum 5a is operated, so that the gap between the recording material carrying sheet 5f and the photosensitive drum 1 is reduced. The configuration can be set arbitrarily. For example, during standby or when the power is off, the transfer drum and the photosensitive drum are separated from each other.

With the above structure, according to the present invention, the ratio of the peripheral length of the photosensitive drum 1 to the peripheral length of the recording material carrier 5f is 1: 1. With such a configuration, the function and effect of the present invention of eliminating the adverse effect brought about by the transfer memory described above is achieved. This point will be described later.

Further, the above-described operational effects achieved by the present invention are obtained when a photosensitive member made of an organic photoconductor as described below (hereinafter referred to as "organic photosensitive member") is used as the photosensitive drum 1. It is remarkable.

That is, although the organic photoreceptor has the advantages of low cost and safety, it has a weak film strength and is easily damaged by contact with the protrusion of the transfer drum 5a, and further, NOx generated by the corona charger when the apparatus is stopped. It has a weak point that it may be damaged. Such a problem is also greatly improved by the configuration in which the ratio of the peripheral length of the photosensitive drum 1 to the peripheral length of the recording material carrier 5f is 1: 1.

Examples 3 to 9 will be described in detail as to the organic photoreceptors that can be effectively used in the present invention.

Embodiment 2 FIG. 2 shows another embodiment of the image forming apparatus according to the present invention. The image forming apparatus of this embodiment is the same as that of the first embodiment shown in FIG.
The difference is that a photosensitive belt 1'is adopted as an image bearing member instead of the photosensitive drum 1 which is an image bearing member in the image forming apparatus, and other configurations and operations are the same. Therefore, members having the same configuration and operation are designated by the same reference numerals, and detailed description thereof will be omitted.

According to this embodiment employing the photoconductor belt 1 ', if the number of constituent members around the photoconductor belt 1'is small, and if it is small, the circumference of the photoconductor belt 1'and the recording material carrier 5f. The area occupied by the photoconductor belt 1'can be set small by devising the arrangement of the photoconductor belt 1'while maintaining the ratio of the circumferences of 1 to 1.

That is, in this embodiment, the ratio of the peripheral length of the photosensitive belt 1'to the peripheral length of the recording material carrier 5f is 1: 1.
To eliminate the effects of transfer, thereby eliminating the need for additional auxiliary means such as post-transfer chargers traditionally required to remove transfer memories,
Also in this respect, the configuration of the entire apparatus can be downsized, which is advantageous.

Example 3 Next, a method for producing a photoconductor (hereinafter referred to as “organic photoconductor”) which is an organic photoconductor that can be preferably used in the present invention will be described.

In the case of producing an organic photoreceptor, the conductive support is provided with a conductive layer in which conductive particles are dispersed in a suitable binder resin on a support such as metal such as aluminum and stainless steel, or paper or plastic. A cylindrical cylinder or film is used. However, when the support itself is conductive, the support may not be provided with a conductive layer.

An undercoat layer (adhesive layer) having a barrier function and an undercoat function can be provided on these conductive supports.

The subbing layer is for improving the adhesiveness of the photosensitive layer, improving the coating property, protecting the conductive support, covering defects on the conductive support, improving the charge injection property from the conductive support, and the photosensitive layer. It is formed for protection against electric breakdown of

Known materials for the undercoat layer include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide copolymerized nylon, glue and gelatin. . These are dissolved in a suitable solvent and coated on a support. The film thickness is about 0.2 μm to 2 μm.

As the charge generating substance, a cyanine dye,
Azo pigments such as azulene dyes, squarylium dyes, pyrylium dyes, tispyrylium dyes, phthalocyanine pigments, anthanthrone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, monoazo pigments, disazo pigments and trisazo pigments. Indigo pigments, quinacridone pigments, asymmetric quinocyanines, quinocyanines, and the like can be used.

As the charge transport material, pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-
Methyl-N-phenylhydrazino-3-methylidene-9
-Ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-
Diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N, N-diphenylhydrazino-3-
Methylidene-10-ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-
Naphthyl-N-phenylhydrazone, p-pyrrolidinobenzaldehyde-N, N-diphenylhydrazone, 1,
3,3-Trimethylindolenine-ω-aldehyde-
Hydrazones such as N, N-diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1
-Phenyl-3- (p-diethylaminostyryl) -5
-(P-diethylaminophenyl) pyrazoline, 1-
[Quinolyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylamino) Phenyl) pyrazoline, 1- [6-methoxypyridyl (2)]-3-
(P-Diethylaminostyryl) -5- (p-diethylaminophenylpyrazoline, 1- [pyridyl (3)]-
3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [lepidyl (2)]-3- (p-diethylaminostyryl) -5-
(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl)
-4-Methyl-5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (α-methyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1-phenyl -3- (p
-Diethylaminostyryl) -4-methyl-5- (p-
Diethylaminophenyl) pyrazoline, 1-phenyl-
3- (α-benzyl-p-diethylaminostyryl)-
Pyrazolines such as 5- (p-diethylaminophenyl) pyrazoline and spiropyrazoline, 2- (p-diethylaminostyryl) -6-diethylaminobenzoxazole, 2- (p-diethylaminophenyl) -4- (p
-Dimethylaminophenyl) -5- (2-chlorophenyl) oxazole-based compounds such as oxazole, 2-
Thiazole compounds such as (p-diethylaminostyryl) -6-diethylaminobenzthiazole, bis (4
-Diethylamino-2-methylphenyl) phenylmethane-based compounds such as phenylmethane, 1,1-bis (4-N, N-diethylamino-2-methylphenyl)
Heptane, 1,1,2,2-tetrakis (4-N, N-
Polyarylalkanes such as dimethylamino-2-methylphenyl) ethane, 5- (4-diphenylaminobenzylidene) -5Hdibenzo [a, d] cycloheptene, 1,2-benzo-3- (d-phenylstyryl)-
A stilbene compound such as 9-n-putylcarbazole can be used.

A method for preparing an organic photoreceptor will be described by taking a case of a function-separated photoreceptor in which a charge transport layer is laminated on a charge generation layer as an example.

A homogenizer, an ultrasonic wave, and the above charge generating substance together with a binder resin and a solvent in an amount of 0.3 to 10 times.
Disperse well by methods such as ball mill, vibration ball mill, sand mill, attritor, and roll mill. This dispersion was coated on the support coated with the subbing layer, dried, and then dried.
A coating film of about 1 to 1 μm is formed.

In this example, since the surface layer serves as the charge transport layer, the fluororesin powder is dispersed therein.

That is, the binder resin and the fluororesin powder are dispersed together with a solvent by a homogenizer, ultrasonic wave, ball mill, sand mill, attritor, roll mill or the like, and a solution of the charge transporting substance and the binder resin is added to this to obtain the desired mixture. The charge transport layer liquid is prepared. The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 4.

As the solvent, aromatic hydrocarbons such as toluene and xylene, dichloromethane, chlorobenzene,
Chlorine hydrocarbons such as chloroform and carbon tetrachloride are used. When applying this solution, for example, a coating method such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method or a curtain coating method can be used, and drying is performed at 10 to 200 ° C. It can be carried out at a temperature in the range of 20 to 150 ° C. for 5 minutes to 5 hours, preferably for 10 minutes to 2 hours under blast drying or static drying. The thickness of the formed charge transport layer is about 10 to 30 μm.

Further, in the case of a photoconductor in which the charge generation layer is coated on the charge transport layer, the charge generation layer serves as the surface layer, and therefore the dispersion-stabilized fluorine resin powder is contained therein. .
This charge generation layer dispersion is prepared by adding and mixing the dispersion prepared by dispersing the fluororesin powder in the binder resin used for the charge generation layer to the charge generation dispersion prepared as described above. The dispersion can be coated on the charge transport layer to obtain a photoreceptor.

When the photosensitive layer has a protective layer, the protective layer serves as a surface layer of the photosensitive layer, and the dispersion-stabilized fluororesin powder is contained in the protective layer. This protective layer can be obtained by applying a dispersion liquid of the fluorine-based resin powder dispersion-stabilized in the resin forming the protective layer onto the photosensitive layer as described above.

Although it is not essential for the organic photoreceptor to have a surface protective layer, the surface protective layer will be described below.

The surface protective layer has a conductive metal powder, and examples of the conductive metal powder include metals such as aluminum, copper, nickel and silver, zinc oxide, titanium oxide, tin oxide,
Metal oxides such as antimony oxide, indium oxide, bismuth oxide, indium oxide doped with tin, tin oxide doped with antimony and zirconium oxide, and one or more thereof are appropriately selected, and the primary particles are 0.3 μm. The following are preferred.

Further, as the fluorine resin powder constituting the surface protective layer, tetrafluoroethylene resin, trifluorochloroethylene resin, tetrafluoroethylene hexafluoropropylene resin,
One or more kinds are appropriately selected from vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride chloride resin and copolymers thereof, but are particularly low-molecular grade and have primary particles of 0.3 μm The following are preferred. Since this value should be shorter than the semiconductor laser beam wavelength, it seems to be too short, but in the implementation system, secondary particles and tertiary particles were inevitably produced, and as a result of experiments considering this, the primary particle size was A value of 0.3 μm or less is an appropriate value.

The content of the conductive metal powder dispersed in the surface layer is appropriately 5 to 90% by weight, preferably 10 to 90% by weight, based on the weight of the solid content of the surface layer. Content rate is 5
If it is less than wt%, the resistance value will be too high and the remaining amount will be high.
If it exceeds 0% by weight, the surface layer has a low resistance, which lowers the charging ability and causes pinholes.

The content of the fluororesin powder dispersed in the surface layer is 1 to 50% by weight based on the weight of the solid content of the surface layer.
Is suitable, and particularly preferably 2 to 30% by weight. If the content is less than 1% by weight, the effect of modifying the surface layer by the fluororesin is not sufficient, while if it exceeds 50% by weight, the light transmittance is lowered and the carrier mobility is also lowered.

The binder resin for forming the surface layer may be a polymeric substance having film-forming properties, but it is not necessary to use a polymer because it has hardness to a certain degree and does not interfere with carrier transportation. Methacrylic acid ester, polystyrene, methacrylic acid ester / styrene copolymer,
Polycarbonate, polyester, polysulfone and the like are preferable.

The curable resin for forming the surface layer is a photocurable resin represented by thermosetting resins such as polyurethane resin, epoxy resin, melamine resin or guanamine resin and polyacrylates as described above. Resins are used.

Next, the method for producing the organic photoconductor will be described more specifically.

Example 4 50 parts by weight of conductive titanium oxide powder coated with tin oxide containing 10% antimony oxide, phenol resin 25
Parts by weight, methyl cellosolve 20 parts by weight, methanol 5 parts by weight and silicone oil (polydimethylsiloxane polyoxyalkylene copolymer, total average molecular weight 3000)
0.002 parts by weight was dispersed for 2 hours with a sand mill using glass beads having a diameter of 1 mm to prepare a conductive paint. Aluminum cylinder (diameter 80mm x length 360m
m) was coated with the above coating by dipping and dried at 140 ° C. for 30 minutes to form a conductive layer having a film thickness of 20 μm.

Next, 30 parts by weight of methoxymethylated nylon resin (number average molecular weight 32000) and 10 parts by weight of alcohol-soluble copolymerized nylon resin (number average molecular weight 29000) are mixed solvent of 260 parts by weight of methanol and 40 parts by weight of butanol. The liquid dissolved therein was applied on the conductive layer by a dipping coater to form an undercoat layer having a film thickness after drying of 1 μm.

Next, the disazo pigment of the following structural formula [I]

[0063]

[Chemical 1] 4 parts by weight, benzal resin 2 parts by weight, and tetrahydrofuran 40 parts by weight are dispersed for 60 hours in a sand mill using glass beads having a diameter of 1 mm, and then diluted with a cyclohexanone / tetrahydrofuran mixed solvent to prepare a charge generation layer coating material. did.

This coating solution was applied onto the above-mentioned undercoat layer by a dipping coating machine to form a charge generation layer having a film thickness after drying of 0.1 μm.

Next, a charge transport material represented by the following structural formula [II]

[0066]

[Chemical 2] And 0 parts by weight of polycarbonate resin (number average molecular weight 25
000) 10 parts by weight are dissolved in a mixed solvent of 20 parts by weight of dichloromethane and 40 parts by weight of monochlorobenzene, and this solution is dip-coated on the charge generation layer to obtain 120 parts.
After drying at 60 ° C. for 60 minutes, a charge transport layer having a film thickness of 20 μm was formed.

Next, 4 parts by weight of an acrylic monomer resin, 5 parts by weight of tin oxide (average primary particle size 0.3 μm), and 1 part by weight of a photopolymerization initiator were dispersed in a solvent of 30 parts by weight of ethanol,
Dissolve, and dip-coat the solution on the charge transport layer to produce a metal halide lamp (560 mW / cm ² : 36
Irradiation was performed for 30 seconds at an illuminance of a sensor having a central sensitivity of 0 nm. As a result, a surface protective layer having a film thickness of 3 μm was formed.

Example 5 The organophotoreceptor of this example was prepared according to the above procedure except that 1 part by weight of tin oxide particles (average primary particle size 0.3 μm) were contained in the surface protective layer of the organophotoreceptor. It was produced under the same conditions as the organic photoconductor of Example 4.

Example 6 The organophotoreceptor of this example was prepared as in Example 4 except that the acrylic monomer resin in the surface protective layer of the organophotoreceptor was an epoxy resin, which was included in an amount of 10 parts by weight. It was produced under the same conditions as the organic photoconductor of.

Example 7 A conductive layer, an undercoat layer, a charge generation layer and a charge transport layer were formed on an aluminum cylinder in the same manner as in Example 4.

Next, 6 parts by weight of a polycarbonate resin (number average molecular weight 25,000), 3 parts by weight of the above charge transport material, polytetrafluoroethylene (average primary particle size 0.3 μm)
1 part by weight was dissolved in a mixed solvent of 200 parts by weight of dichloromethane and 300 parts by weight of monochlorobenzene, and this solution was spray coated on the charge transport layer and dried at 120 ° C. for 60 minutes to give a surface having a thickness of 5 μm. A photoconductor was prepared under the same conditions as the organic photoconductor of Example 4 except that the protective layer was formed.

Example 8 The organophotoreceptor of this example does not have a surface protective layer of the organophotoreceptor and contains 10% of polytetrafluoroethylene particles (average primary particle size 0.3 μm) in the charge transport layer. Other than the above, the organic photoreceptor of Example 7 was manufactured under the same conditions.

Example 9 The organophotoreceptor of this example was the same as Example 7 except that the average primary particle diameter of the polytetrafluoroethylene particles in the surface protective layer of the photoreceptor of Example 4 was 0.1 μm. It was produced under the same conditions as.

The organic photoconductors shown in the above examples have the merit of organic polymer photoconductors that are safe and inexpensive. Furthermore, these photoreceptors have a small initial dark attenuation,
Further, since the surface protection layer has high wear resistance and the change in film thickness due to abrasion after endurance, that is, the change in capacitance is small, the change in dark attenuation is small.

By using such an organic photoreceptor in the image forming apparatus of the present invention, the color balance of the color image due to the influence of dark attenuation when the photosensitive drum 1 is enlarged to the same circumference as the transfer drum 5a. It is possible to prevent the change, and the peripheral lengths of the photosensitive drum 1 and the transfer drum 5a are 1: 1
Could be set to.

On the contrary, the photoconductor having the surface protective layer may be strongly affected by the transfer as described above, and the constitution of the present invention is effective in making full use of the photoconductor having the surface protective layer.

[0077]

As described above, the image forming apparatus according to the present invention is configured such that the ratio of the peripheral length of the image bearing member to the peripheral length of the recording material bearing member is 1: 1. Even if the developing means of the developing method is adopted, it is possible to obtain an image having no density difference due to the transfer memory, and even if an organic photoconductor having a surface protective layer is used as the image carrier, Since the photoconductor can be used in the configuration, it is possible to prevent the photoconductor from being worn and to extend the replacement interval of the photoconductor.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional configuration diagram of another embodiment of the image forming apparatus according to the present invention.

FIG. 3 is a cross-sectional configuration diagram of a conventional image forming apparatus.

[Explanation of symbols]

 1 image carrier 5 transfer device 4 developing device 5f recording material carrier

Claims (3)

[Claims] 1. An electrostatic latent image formed on an image bearing member is made into a visible image by reversal development, and this visible image is electrostatically transferred onto a recording material carried on a recording material carrying member to form an image. In the image forming apparatus to be formed, the ratio of the peripheral length of the image carrier to the peripheral length of the recording material carrier is 1: 1. 2. The image forming apparatus according to claim 1, wherein the image carrier is an organic photoconductor. 3. The image bearing member is a photosensitive member containing a conductive metal particle having a primary particle diameter of 0.3 μm or less or a fluorine resin in a surface layer of a photosensitive layer on a conductive support. Item 1
Image forming device.