JPH08160763A - Image forming device - Google Patents

Abstract

PURPOSE: To prevent irregularities from occurring when toner is moved and to enhance transfer efficiency by restricting the sum of the surface roughness of a first image carrier and the surface roughness of an intermediate transfer body to be equal to or under a prescribed value. CONSTITUTION: The sum of the surface roughness Rmax of the first image carrier 71 and the surface roughness Rmax of the intermediate transfer body 72 is set to be <=20μm. That means, a distance that the toner 73 is moved to the transfer body 72 from the surface of a photoreceptive drum being the first image carrier 71 becomes short by reducing the sum of the surface roughness Rmax 74 of the first image carrier 71 and the surface roughness Rmax 75 of the transfer body 72. As the result, since the toner 73 can be linearly moved, the irregularities in an image is reduced. Besides, the detaching property of the toner 73 is increased and the transfer efficiency is enhanced because the distance that the toner 73 is moved to the transfer body 72 from the surface of the photoreceptive drum being the first image carrier 71 becomes short.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, and more particularly to a toner image formed on a first image carrier, which is once transferred onto an intermediate transfer member and then transferred to a second image carrier. And an image forming apparatus such as a copying machine, a printer or a fax machine, which is further transferred onto the image carrier to obtain an image formed product.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member is
Effective as a color image forming apparatus or a multi-color image forming apparatus that sequentially stacks and transfers a plurality of component color images of color image information or multi-color image information to synthesize a color image or a multi-color image and outputs a reproduced image formed product. Alternatively, it is effective as an image forming apparatus having a color image forming function and a multicolor image forming function, and it is possible to obtain an image having no misregistration (color misregistration) of each component color image.

FIG. 1 shows a schematic view of an example of an image forming apparatus which is a transfer apparatus using an intermediate transfer member having a roller shape. FIG. 1 shows a color image forming apparatus (copier or laser beam printer) using an electrophotographic process, which uses an elastic roller 20 having a medium resistance as an intermediate transfer member. Reference numeral 1 in FIG. 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter,
It is referred to as a photosensitive drum), and is rotationally driven in the clockwise direction indicated by an arrow at a predetermined peripheral speed (process speed).

In the course of rotation, the photosensitive drum 1 is uniformly charged by a primary charger (corona discharger) 2 to a predetermined polarity and potential, and then an image exposure means (not shown) (color separation / combination of color original image). The image exposure optical system, a scanning exposure system by a laser scanner that outputs a laser beam modulated corresponding to a time-series electric digital pixel signal of image information, and the like) undergoes image exposure 3 to receive the first image of the target color image. An electrostatic latent image corresponding to the color component image (for example, magenta component image) is formed.

Next, the electrostatic latent image is developed by the first developing device 41 (magenta developing device) by the magenta toner M which is the first color. At this time, the second to fourth developing devices 42, 4
3, 44 (cyan, yellow, black) developing units)
Is off and does not act on the photosensitive drum 1, and the magenta toner image of the first color is not affected by the second to fourth developing units 42 to 44.

The intermediate transfer member 20 is rotationally driven in the counterclockwise direction indicated by the arrow at the same peripheral speed as the photosensitive drum 1. The intermediate transfer member 20 of the present embodiment is composed of a pipe-shaped core bar 21 and an elastic layer 22 formed on the outer peripheral surface thereof. While the first-color magenta toner image formed and carried on the photosensitive drum 1 passes through the nip portion between the photosensitive drum 1 and the intermediate transfer body 20, the primary transfer bias applied to the intermediate transfer body 20 causes By the electric field formed, the intermediate transfer is sequentially performed on the outer peripheral surface of the intermediate transfer body 20. The transfer process from the photosensitive drum to the intermediate transfer body is called primary transfer.

The surface of the photosensitive drum 1 which has finished transferring the magenta toner image of the first color onto the intermediate transfer member 20 is cleaned by the cleaning device 14. Similarly, the second color cyan toner image, the third color yellow toner image, and the fourth color black toner image are sequentially transferred onto the intermediate transfer body 20 in a superimposed manner to form a composite color toner image corresponding to the target color image. It is formed.

Reference numeral 25 denotes a transfer roller, which is arranged in parallel with the intermediate transfer member 20 so as to be in bearing and in contact with the lower surface. The primary transfer bias for sequentially superimposing and transferring the toner images of the first to fourth colors from the photosensitive drum 1 to the intermediate transfer body 20 has a polarity (+) opposite to that of the toner, and the bias power source 6 is used.
It is applied from 1. The applied voltage is, for example, +2 kV to +
It is in the range of 5 kV.

In the step of sequentially transferring the toner images of the first to fourth colors from the photosensitive drum 1 to the intermediate transfer body 20, the transfer roller 25 and the intermediate transfer body cleaner 35 can be separated from the intermediate transfer body 20. is there. Intermediate transfer body 20
When transferring the composite color toner image superimposed and transferred onto the transfer material 24, which is the second image carrier, the transfer roller 25 is brought into contact with the intermediate transfer member 20 and the intermediate transfer member 25 moves from the paper feeding cassette 9 to the intermediate position. The transfer material 24 is fed to the contact nip between the transfer body 20 and the transfer roller 25 at a predetermined timing, and at the same time, the secondary transfer bias is applied to the transfer roller 25 from the bias power supply 29. The secondary transfer bias causes the synthetic color toner image to be transferred from the intermediate transfer body 20 to the transfer material 24 which is the second image carrier. This process is called secondary transfer. The transfer material 24 that has received the toner image transfer is the fixing device 15
And is heated and fixed.

After the image transfer to the transfer material 24 is completed, the transfer residual toner on the intermediate transfer body 20 is removed by the intermediate transfer body cleaner 3.
It is cleaned by the contact of 5. A color electrophotographic apparatus having an image forming apparatus using the above-mentioned intermediate transfer member,
A conventional color electrophotographic apparatus having an image forming apparatus for adhering or adsorbing a second image support on a transfer drum and transferring an image from the first image support to the second image support, for example, Japanese Patent Application Laid-Open Publication No. It is superior to the transfer method as described in Japanese Patent Laid-Open No. 63-301960 in the following points. That is, there is little color misregistration at the time of superimposing the toner images of the respective colors, and as shown in FIG. 1, there is no processing or control on the second image support (for example, gripping by a gripper, adsorption, curvature Since the image can be transferred from the intermediate transfer member without the need for holding the second image supporting member, a wide variety of second image supporting members can be selected. For example, from thin paper (40 g / m ² paper) to thick paper (200 g / m ² paper)
It is possible to transfer regardless of the width of the second image support, the length of the second image support, the thickness of the second image support, and the thickness of the second image support.In addition, it is possible to handle envelopes, postcards, label paper, etc. It is possible.

Further, since the intermediate transfer member has excellent rigidity, dimensional accuracy such as dents, distortions, and deformations does not easily occur even if it is repeatedly used, so that the frequency of replacement of the intermediate transfer member can be reduced. .

[0012]

As described above, due to the advantages of using the intermediate transfer member, color copying machines, color printers and the like using this image forming apparatus have already started to operate in the market. However, these color electrophotographic apparatuses do not always function as apparatuses that fully utilize the above-mentioned advantages to satisfy and satisfy user's expectations. When the image forming apparatus using the intermediate transfer member is actually used repeatedly in various environments, it still has the following problems to be overcome.

When the toner moves from the surface of the first image carrier, for example, the photosensitive drum to the intermediate transfer member, if the moving distance is large, it becomes difficult for the toner to move linearly, and thus the first image carrier. It becomes impossible to properly transfer the toner held on the intermediate transfer body to a predetermined position.
As a result, the transferred image sometimes becomes a so-called uneven image.

Further, since the transfer efficiency from the first image carrier, for example, the photosensitive drum to the intermediate transfer member, is not sufficiently high, a cleaning device which must be provided for the photosensitive drum and the intermediate transfer member is indispensable. Moreover, since a large amount of transfer residual toner is cleaned, the load on the apparatus becomes large, and the cleaning apparatus may be considerably complicated in structure and expensive.

As measures against these, for example, Japanese Patent Laid-Open No. 59-5.
0475, JP-A-59-202477, JP-A-3-242667, and JP-A-4-303871.
As can be seen in the publication, an intermediate transfer member having a reduced surface roughness is known, but this transfer unevenness and insufficient transfer efficiency from the first image carrier to the intermediate transfer member are In some cases, it could not be solved simply by improving the surface roughness of only the intermediate transfer member.

That is, as shown in FIG. 6, the intermediate transfer member 7
Even if the individual surface roughness Rmax75 of No. 2 is reduced, if the surface roughness Rmax74 of the photosensitive drum that is the first image carrier 71 is large, it becomes difficult for the toner 73 to move linearly, and transfer unevenness occurs. However, the transfer efficiency may be insufficient due to the long moving distance of the toner 73.

Similarly, as shown in FIG. 7, the surface roughness Rmax of the photosensitive drum, which is the first image carrier 71, is independent.
Even if 74 is made small, if the surface roughness Rmax 75 of the intermediate transfer body 72 is large, it becomes difficult for the toner 73 to move linearly, transfer unevenness occurs, and further, the moving distance of the toner 73. However, the transfer efficiency may be insufficient due to the long length.

Naturally, as shown in FIG. 8, if the surface roughness Rmax74 of the photosensitive drum, which is the first image carrier 71, is large and the surface roughness Rmax75 of the intermediate transfer member 72 is also large, It becomes difficult for the toner 73 to move linearly, and transfer unevenness occurs,
In addition, the transfer distance of the toner 73 is long, which may result in insufficient transfer efficiency.

The present invention proposes an image forming apparatus which solves the above problems. That is, the object of the present invention is to prevent the occurrence of unevenness when the toner moves from the surface of the photosensitive drum, which is the first image carrier, to the intermediate transfer member, and to transfer the toner from the first image carrier to the intermediate transfer member. Very high transfer efficiency,
An object is to provide an image forming apparatus.

[0020]

Means for Solving the Problems As a result of intensive studies made by the present inventors in order to achieve the above object, the sum of the surface roughness Rmax of the first image carrier and the surface roughness Rmax of the intermediate transfer member is obtained. It was found that the above object can be achieved by limiting the value to a predetermined value or less, and the image forming apparatus of the present invention was completed.

That is, the image forming apparatus of the present invention is an image forming apparatus for transferring an image formed on a first image carrier to an intermediate transfer member and then further transferring it to a second image carrier. The sum of the surface roughness Rmax of the first image carrier and the surface roughness Rmax of the outer intermediate transfer member is 20 μm or less. In an image forming apparatus that transfers the image formed on the first image carrier to the intermediate transfer member and then further transfers the image on the second image carrier, as shown in FIG. Surface roughness Rmax7 of the carrier 71
4 and the surface roughness Rmax 75 of the intermediate transfer body 72 are reduced, the distance that the toner moves from the surface of the photosensitive drum, which is the first image carrier, to the intermediate transfer body becomes shorter, and the toner 73 becomes By being able to move linearly, image unevenness is reduced, and the distance that toner moves from the surface of the photosensitive drum, which is the first image bearing member, to the intermediate transfer member is shortened. The releasability is increased and the transfer efficiency is improved.

The effect of the present invention can be obtained if the total of the surface roughness Rmax of the first image carrier and the surface roughness Rmax of the intermediate transfer member is 20 μm or less, but preferably 15 μm.
The following is desirable, and more preferably 10 μm or less. As a method for reducing the surface roughness of the first image bearing member, there are a method of adjusting the atmospheric humidity at the time of applying the coating material for the surface portion, a method of polishing and the like.

When adjusting the coating atmosphere at the time of coating the coating material for the surface of the first image carrier, the humidity is 40% RH.
The above is desirable. If it is less than 40% RH, the drying rate of the coating material becomes too fast, and the difference in the drying rate between the surface portion and the inside may cause the surface roughness to deteriorate.
The surface roughness R of the first image carrier, which is a constituent feature of the present invention
20 and the surface roughness Rmax of the intermediate transfer member
It becomes difficult to reduce the thickness to μm or less.

For polishing the surface of the first image carrier, there are a method using a grinder, a belt grinding method, a barrel processing method and the like. As a method for reducing the surface roughness of the first image carrier, the above-mentioned methods are the main methods, but the method is not limited to these. Also,
As a method of reducing the surface roughness of the intermediate transfer member, there are a method of adjusting the atmospheric humidity at the time of applying the coating material for the surface portion, a method of polishing and the like.

When adjusting the coating atmosphere at the time of coating the coating material for the surface portion of the intermediate transfer member, the humidity is preferably 40% RH or more. If it is less than 40% RH, the drying speed of the coating material becomes too fast and a difference in the drying speed between the surface portion and the inside may occur, which may deteriorate the surface roughness, which is a constituent feature of the present invention. Surface roughness Rmax of first image carrier
It becomes difficult to set the total of the surface roughness Rmax of the intermediate transfer member to 20 μm or less.

In the present invention, the surface roughness Rmax
Is measured according to JIS B0601. When polishing the surface of the intermediate transfer member, there are a method using a grinder, a belt grinding method, a barrel processing method, and the like. As a method of reducing the surface roughness of the intermediate transfer member,
The methods described above are the main methods, but the method is not limited to these.

The photosensitive drum which is the first image carrier used in the present invention is, for example, a conductive support provided with an organic photosensitive layer, and if necessary, a barrier function and an adhesive function may be provided between the two. Some have a subbing layer. These organic photoreceptors are often used as the first image carrier because of their high safety, good chargeability, good productivity, and low cost.

As the conductive support constituting the first image carrier used in the present invention, the following can be used, for example. (1) Aluminum, aluminum alloy, stainless steel,
Metals such as copper. (2) A thin film is formed by vapor-depositing or laminating a metal such as aluminum, palladium, rhodium, gold or platinum on the surface of a non-conductive support such as glass, resin or paper or the conductive support of (1) above. What I did. (3) A layer of a conductive compound such as a conductive polymer, tin oxide or indium oxide is vapor-deposited or applied on the surface of a non-conductive support such as glass, resin or paper or the conductive support of the above (1). Formed by

As the material for forming the undercoat layer, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, methyl cellulose, casein, polyamide, glue, gelatin, etc. are usually used. The organic photosensitive layer includes a charge generation layer and a charge transport layer, and a protective layer may be provided on the photosensitive layer for controlling charge injection, for example.

The charge generating layer can be formed by dispersing the charge generating substance in a suitable binder and coating the same on a conductive support. The charge generation layer can also be formed as a thin film on the conductive support by a dry method such as vapor deposition, sputtering or CVD. Examples of the charge generating substance include the following substances. These charge generating substances may be used alone or in combination of two or more kinds. (1) Azo pigments such as monoazo, bisazo and trisazo. (2) Indigo pigments such as indigo and thioindigo. (3) Phthalocyanine-based pigments such as metal phthalocyanine and non-metal phthalocyanine. (4) Perylene-based pigments such as perylene anhydride and perylene imide. (5) Polycyclic quinone pigments such as anthraquinone and hydroquinone. (6) Squalilium dye. (7) Pyrylium salts and thiopyrylium salts. (8) Triphenylmethane dye.

The binder can be selected from a wide range of binder resins such as polycarbonate resin, polyester resin, polyacrylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, acetic acid. Examples include, but are not limited to, vinyl resin, phenol resin, silicone resin, polysulfone resin, styrene-butadiene copolymer resin, alkyd resin, epoxy resin, urea resin, vinyl chloride-vinyl acetate copolymer resin, and the like. is not.

Further, these may be used alone or in combination of two or more as a homopolymer or a copolymer polymer. The amount of resin contained in the charge generation layer is 80% by weight or less, preferably 40% by weight or less. Further, the film thickness of the charge generation layer is 5
A thin film layer having a thickness of not more than μm, particularly 0.01 μm to 2 μm is preferable. Various sensitizers may be further added to the charge generation layer.

The charge transport layer is formed by coating and drying a paint in which a charge transport substance and a binder resin are dissolved in a solvent. Examples of the charge transport material include various triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triarylmethane compounds, and the like. Further, as the binder resin, those mentioned above can be used. For coating the organic photosensitive layer, any conventionally known method such as dipping method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, and roll coating method can be used.

As the intermediate transfer member used in the present invention, for example, a roller shape (FIG. 2) having an elastic layer 101 made of rubber, elastomer or resin on the outer peripheral surface of a cylindrical conductive support (core metal) 100, Further, a roller shape having one coating layer 102 on the outer peripheral surface of the elastic layer 101 (FIG. 3) or a roller shape having two coating layers 102 and 103 on the outer peripheral surface of the elastic layer 101 (FIG. 4). Further, the belt shape 104 as shown in FIG. 5 and intermediate transfer members of various modes can be selected according to the purpose and need. In consideration of color misregistration in superimposing images and durability due to repeated use, a more preferable shape of the intermediate transfer body is a roller shape.

The cylindrical conductive support (core bar) can be produced using a metal or alloy such as aluminum, iron, copper and stainless steel, a conductive resin in which carbon or metal particles are dispersed, and the like. Examples of the shape include a cylindrical shape as described above, a shape in which a shaft penetrates through the center of the cylinder, and a shape in which the inside of the cylinder is reinforced. An elastic layer of the intermediate transfer member used in the present invention, a rubber used to form the coating layer,
Examples of elastomers and resins include elastomers and rubbers such as styrene-butadiene rubber, high styrene rubber, butadiene rubber, isoprene rubber, ethylene-propylene copolymer, nitrile butadiene rubber, chloroprene rubber, butyl rubber, silicone rubber, and fluorine. Examples thereof include rubber, nitrile rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber and norbornene rubber. Further, the resins include polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene. -Acrylic ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer,
Styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer,
Styrene-phenyl methacrylate copolymer, etc.), styrene-α-chloromethyl acrylate copolymer, styrene-
Styrene resins such as acrylonitrile-acrylic acid ester copolymers (styrene or styrene-substituted homopolymers or copolymers), vinyl chloride resins, styrene-
Vinyl acetate copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene Examples thereof include resins and polyvinyl butyral resins.

The thickness of the elastic layer is preferably 0.5 mm or more, more preferably 1 mm or more, and particularly preferably 1 to 10 mm. The film thickness of the coating layer is preferably a thin film in order to convey the flexibility of the lower elastic layer to another coating layer on the coating layer or to the surface of the photoconductor, specifically 3 mm or less. , 2 mm or less, particularly 20 μm to 1
It is preferably mm.

The volume resistance of the intermediate transfer member used in the present invention is 1
It is preferably 0 ¹ to 10 ¹³ Ω, and particularly 10 ²
It is preferably from 10 to 10 ¹⁰ Ω. Furthermore, the volume resistivity of the surface layer is preferably within these ranges.

[0038]

EXAMPLES Examples will be described below. Example 1 (Preparation of Photoreceptor) An aluminum cylinder of 80 mmφ × 360 mm was used as a support, and soluble nylon 5
% Methanol solution was applied by dip coating to form an undercoat layer having a thickness of 1 μm. On the other hand, 10 parts by weight of disazo pigment, 5 parts by weight of polyvinyl butyral and 50 parts by weight of cyclohexanone are added to 1 m.
It was dispersed for 20 hours by a sand mill using mφ glass beads. To this dispersion, 100 parts by weight of methyl ethyl ketone was added and coated on the undercoat layer to form a charge generation layer having a thickness of 0.1 μm. Next, 10 parts by weight of bisphenol Z-type polycarbonate and 10 parts by weight of hydrazone compound are dissolved in 65 parts by weight of monochlorobenzene, and dip-coated to form 18
A charge transport layer having a thickness of μm was formed. The humidity of the coating atmosphere at this time was 65%. Rmax of this photoconductor is 0.
It was 8 μm. (Preparation of intermediate transfer member) EPDM 100 parts by weight, zinc oxide 5 parts by weight, higher fatty acid 1 part by weight, conductive carbon black 5 parts by weight, paraffin oil 10 parts by weight, sulfur 2 parts by weight, vulcanization accelerator MBT 1 part by weight, Vulcanization accelerator TMTD
1.5 parts by weight and 1.5 parts by weight of the vulcanization accelerator ZnMDC were mixed for 20 minutes while cooling with a two-roll to form a compound, and the compound for the elastic layer was 182 mmφ.
A rubber roller having an elastic layer was obtained by transfer molding and vulcanization on the surface of an aluminum cylindrical roller having a size of 320 mm and a thickness of 5 mm using a mold. Next, a mixture of 50 parts by weight of polyurethane prepolymer, 40 parts by weight of conductive titanium oxide, 5 parts by weight of dispersion aid, 100 parts by weight of toluene, and 50 parts by weight of curing agent is spray-coated on this to form a surface layer. A transfer body was obtained. The humidity of the coating atmosphere at this time was 65%. Rmax of this intermediate transfer member
Was 8.7 μm, and the total Rmax of the photoconductor and the intermediate transfer member was 9.5 μm. (Evaluation) The above-mentioned photoreceptor and intermediate transfer member were mounted on the full-color electrophotographic apparatus shown in FIG. 1 and a full-color image print test was conducted. The full-color print image had a uniform image quality in a solid image.

The transfer efficiency (primary transfer efficiency) from the photosensitive drum to the intermediate transfer member was 96%, which was a good value. Comparative Example 1 (Preparation of Photoreceptor) An aluminum cylinder of 80 mmφ × 360 mm was used as a support, and soluble nylon 5 was used as the support.
% Methanol solution was applied by dip coating to form an undercoat layer having a thickness of 1 μm. On the other hand, 10 parts by weight of disazo pigment, 5 parts by weight of polyvinyl butyral and 50 parts by weight of cyclohexanone are added to 1 m.
It was dispersed for 20 hours by a sand mill using mφ glass beads. To this dispersion, 100 parts by weight of methyl ethyl ketone was added and coated on the undercoat layer to form a charge generation layer having a thickness of 0.1 μm. Next, 10 parts by weight of bisphenol Z-type polycarbonate and 10 parts by weight of hydrazone compound are dissolved in 65 parts by weight of monochlorobenzene, and dip-coated to form 18
A charge transport layer having a thickness of μm was formed. The humidity of the coating atmosphere at this time was 5%. Rmax of this photoconductor is 9.4
μm. (Preparation of intermediate transfer member) An intermediate transfer member was prepared in the same manner as in Example 1. The Rmax of this photoconductor is 11.8 μm, and the total Rmax of the photoconductor and the intermediate transfer body is 21.
It was 2 μm. (Evaluation) The above-mentioned photoreceptor and intermediate transfer member were mounted on the full-color electrophotographic apparatus shown in FIG. 1 and a full-color image print test was conducted. The full-color printed image had unevenness in the solid image.

The transfer efficiency (primary transfer efficiency) from the photosensitive drum to the intermediate transfer member was 87%, which was a poor value with many transfer residues. Comparative Example 2 (Preparation of Photoreceptor) A photoreceptor was prepared in the same manner as in Example 1. The Rmax of this photoconductor was 0.8 μm. (Preparation of intermediate transfer member) EPDM 100 parts by weight, zinc oxide 5 parts by weight, higher fatty acid 1 part by weight, conductive carbon black 5 parts by weight, paraffin oil 10 parts by weight, sulfur 2 parts by weight, vulcanization accelerator MBT 1 part by weight, Vulcanization accelerator TMTD
1.5 parts by weight and 1.5 parts by weight of the vulcanization accelerator ZnMDC were mixed for 20 minutes while cooling with a two-roll to form a compound, and the compound for the elastic layer was 182 mmφ.
A rubber roller having an elastic layer was obtained by transfer molding and vulcanization on the surface of an aluminum cylindrical roller having a size of 320 mm and a thickness of 5 mm using a mold. Next, a mixture of 50 parts by weight of polyurethane prepolymer, 40 parts by weight of conductive titanium oxide, 5 parts by weight of dispersion aid, 100 parts by weight of toluene, and 50 parts by weight of curing agent is spray-coated on this to form a surface layer. A transfer body was obtained. The humidity of the coating atmosphere at this time was 7%. Rmax of this photoconductor is 2
It was 5.6 μm, and the total Rmax of the photoconductor and the intermediate transfer member was 26.4 μm. (Evaluation) The above-mentioned photoreceptor and intermediate transfer member were mounted on the full-color electrophotographic apparatus shown in FIG. 1 and a full-color image print test was conducted. The full-color printed image had unevenness in the solid image.

The transfer efficiency (primary transfer efficiency) from the photosensitive drum to the intermediate transfer member was 82%, which was a poor value with many transfer residues.

[0042]

As described above, in the image forming apparatus of the present invention, the moving distance of the toner becomes short, the unevenness of the image at the time of the transfer does not occur, the transfer efficiency is increased, and the image is always uniform. It is possible to obtain a clear image.

[Brief description of drawings]

FIG. 1 is a schematic view of a color image output device using a roller-shaped intermediate transfer member.

FIG. 2 is a cross-sectional view of a roller-shaped intermediate transfer member having an elastic layer.

FIG. 3 is a sectional view of a roller-shaped intermediate transfer member having a coating layer on an elastic layer.

FIG. 4 is a cross-sectional view of a roller-shaped intermediate transfer member having a plurality of coating layers on an elastic layer.

FIG. 5 is a schematic diagram of a color image output device using an intermediate transfer belt.

FIG. 6 is a surface roughness R of the first image carrier and the intermediate transfer member.
FIG. 6 is a schematic cross-sectional view showing the relationship between max and toner transfer unevenness.

FIG. 7 is a surface roughness R of the first image carrier and the intermediate transfer member.
FIG. 6 is a schematic cross-sectional view showing the relationship between max and toner transfer unevenness.

FIG. 8 is a surface roughness R of the first image carrier and the intermediate transfer member.
FIG. 6 is a schematic cross-sectional view showing the relationship between max and toner transfer unevenness.

FIG. 9 is a surface roughness R of the first image carrier and the intermediate transfer member.
FIG. 6 is a schematic cross-sectional view showing the relationship between max and the transfer state of toner.

[Explanation of symbols]

 1 Photosensitive Drum 2 Primary Charger 3 Image Exposure Means 9 Paper Feed Cassette 14 Photosensitive Drum Cleaning Device 15 Fixing Device 20 Intermediate Transfer Body 21 Core Metal 22 Elastic Layer 24 Transfer Material 25 Transfer Roller 35 Intermediate Transfer Body Cleaner 41 Magenta Color Development Device 42 cyan developing device 43 yellow developing device 44 black developing device 61 bias power source 71 first image carrier 72 intermediate transfer member 73 toner 74, 75 surface roughness Rmax 100 core metal 101 elastic layer 102 coating layer 103 coating layer 104 Belt-shaped intermediate transfer member

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Akihiko Nakazawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hiroyuki Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Within the corporation

Claims (4)

[Claims] 1. An image forming apparatus for transferring an image formed on a first image bearing member onto an intermediate transfer member, and further transferring the image onto a second image bearing member. An image forming apparatus characterized in that the sum of the surface roughness Rmax and the surface roughness Rmax of the intermediate transfer member is 20 μm or less. 2. The image forming apparatus according to claim 1, wherein the first image carrier is an organic photoconductor. 3. The image forming apparatus according to claim 2, wherein the surface layer of the organic photoconductor is formed by coating. 4. The image forming apparatus according to claim 1, wherein the surface layer of the intermediate transfer member is formed by coating.