JPH09325621A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the unevenness of an image at a wavy part and to prevent the tension member mark or the shrink mark of the finally obtained image by providing surface waviness having specified wavelength on the surface of an intermediate transfer drum and setting the average waveheight of the surface waviness to be equal to or under a specified value. SOLUTION: The average waveheight of the surface waviness of the surface of an intermediate transfer drum 30, that is, the surface waviness of the drum 30 having the surface waviness whose average wavelength is >=0.1mm and <3mm is set to <=10μm. Thus, the difference of distance that toner is moved from the surface of a photoreceptor drum 1 being a 1st image carrier to the drum 30 is reduced between the projected part and the recessed part of the waviness of the drum 30. Therefore, irregular transfer at the primary transfer time is reduced and the retransfer of the projected part at the second primary transfer time is eliminated, so that the tension member mark is reduced. Furthermore, faulty cleaning caused by the toner remaining in the recessed part after secondary transfer is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic method, and more particularly, to a second image after a toner image formed on a first image carrier is once transferred to an intermediate transfer member. The present invention relates to an electrophotographic image forming apparatus which transfers an image on an image carrier to obtain an image formed product.

[0002]

2. Description of the Related Art An image forming apparatus using an intermediate transfer member includes:
A color image forming apparatus or a multi-color image forming apparatus or a multi-color image forming apparatus that sequentially outputs a plurality of component color images of the color image information or the multi-color image information and outputs an image formed by combining and reproducing the color image or the multi-color image. It is effective as an image forming apparatus having a forming function and a multicolor image forming function.

The intermediate transfer member used in the present invention has, for example, a belt shape or a roller shape having an elastic layer made of at least rubber, elastomer or resin on a conductive support, and one or more layers above the elastic layer. The shape of the roller having the coating layer of, and various modes are selected depending on the purpose and need. That is, when miniaturization of the image forming apparatus is demanded, a belt shape having a high degree of freedom of shape is mainly used, and an image without color misregistration (color misregistration) of each color image of the color image forming apparatus is used. When it is desired to obtain easily, a drum shape having excellent rigidity of the intermediate transfer body is mainly used. An example of the apparatus is shown in FIGS.

The following is a description of the intermediate transfer belt, but the shape is not limited to this.

A schematic view of an example of an image forming apparatus using an intermediate transfer belt is shown in FIG.

FIG. 1 shows a color image forming apparatus (copier or laser beam printer) utilizing an electrophotographic process. The intermediate transfer belt 20 uses a medium-resistance elastic body.

Reference numeral 1 denotes a rotary drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) which is repeatedly used as a first image bearing member, and has a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow. It is driven to rotate.

The photosensitive drum 1 is rotated and the primary charger 2
Is charged uniformly to a predetermined polarity and potential, and then image exposure means 3 (not shown) (modulation in accordance with a color original image separation / imaging exposure optical system, a time-series electric digital pixel signal of image information) Receiving an image exposure 3 by a scanning exposure system using a laser scanner that outputs a converted laser beam, thereby forming an electrostatic latent image corresponding to a first color component image (for example, a yellow color component image) of a target color image. Is done.

Then, the electrostatic latent image is developed by the first developing device (yellow developing device 41) with the yellow toner Y which is the first color. At this time, the developing units of the second to fourth developing units (magenta color developing unit 42, cyan color developing unit 43, black color developing unit 44) are in the operation-off state and do not act on the photosensitive drum 1. The first color yellow toner image is not affected by the second to fourth developing devices.

The intermediate transfer belt 20 is rotationally driven in the clockwise direction at the same peripheral speed as the photosensitive drum 1.

The above-mentioned first formed and carried on the photosensitive drum 1.
By the electric field formed by the primary transfer bias applied from the primary transfer roller 62 to the intermediate transfer belt 20 while the yellow toner image of the color passes through the nip portion between the photosensitive drum 1 and the intermediate transfer belt 20, Intermediate transfer belt 2
Intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of 0.

The surface of the photosensitive drum 1 on which the transfer of the yellow toner image of the first color corresponding to the intermediate transfer belt 20 has been completed is cleaned by the cleaning device 13.

Similarly, a magenta toner image of the second color, a cyan toner image of the third color, and a black toner image of the fourth color are successively superimposed and transferred onto the intermediate transfer belt 20 to correspond to the desired color image. The combined color toner image is formed.

Reference numeral 63 denotes a secondary transfer roller, which corresponds to the secondary transfer counter roller 64 and is supported in parallel with the intermediate transfer belt 20.
Is disposed on the lower surface of the so as to be separable.

The primary transfer bias for sequentially superposing and transferring the toner images of the first to fourth colors from the photosensitive drum 1 to the intermediate transfer belt 20 has a polarity opposite to that of the toner, and the bias power supply 29.
Is applied. The applied voltage is, for example, +100 V or more.
The range is +2 kV.

In the primary transfer process of the toner images of the first to third colors from the photosensitive drum 1 to the intermediate transfer belt 20, 2
The next transfer roller 63 and the intermediate transfer belt cleaner 7 can be separated from the intermediate transfer belt 20.

The transfer of the composite color toner image transferred onto the intermediate transfer belt 20 onto the transfer material 24, which is the second image carrier, is performed when the secondary transfer roller 63 is brought into contact with the intermediate transfer belt 20. From the paper feed roller 11 to the transfer material guide 1
0 through the intermediate transfer belt 20 and the secondary transfer roller 63.
The transfer material 24 is fed at a predetermined timing to the contact nip with and the secondary transfer bias is applied from the bias power source 28 to the secondary transfer roller 63. By this secondary transfer bias, the composite color toner image is transferred (secondary transfer) from the intermediate transfer belt 20 to the transfer material 24 which is the second image carrier. The transfer material 24 which has received the transfer of the toner image is the fixing device 15.
And is heated and fixed.

After the image transfer to the transfer material 24 is completed, the cleaning charging member 7 is brought into contact with the intermediate transfer belt 20,
The bias power source 26 supplies a bias having a polarity opposite to that of the photosensitive drum 1.
By applying the voltage from the above, a charge having a polarity opposite to that of the photosensitive drum 1 is applied to the toner (transfer residual toner) remaining on the intermediate transfer belt 20 without being transferred to the transfer material 24.

The transfer residual toner is electrostatically transferred to the photosensitive drum 1 at the nip portion with the photosensitive drum 1 and in the vicinity thereof, whereby the intermediate transfer member is cleaned.

In a color electrophotographic apparatus having an image forming apparatus using the above-mentioned intermediate transfer belt, a conventional transfer drum is stuck or adsorbed, and an image is transferred from the first image carrier to the transfer drum. A color electrophotographic apparatus having an image forming apparatus, for example, JP-A-63-301960.
In comparison with the transfer device as described in the publication,
Since the image can be transferred from the intermediate transfer belt to the transfer material serving as the second image carrier without requiring any processing or control (for example, gripping by a gripper, adsorbing, giving a curvature, etc.), an envelope, From thin paper (40 g / m ² paper) to thick paper (200 g / m ² paper), such as postcards and label paper, regardless of the width, width, length, or thickness of the second image carrier It has the advantage that the body can be selected in a wide variety.

Due to these advantages, color copiers, color printers and the like using the intermediate transfer belt have already started to operate in the market.

In the image forming apparatus of FIG. 1, the developer is primarily transferred from the photosensitive drum 1 to the intermediate transfer belt 20, and at the same time, the transfer residual developer on the intermediate transfer belt 20 generated in the previous image forming step is generated. May be returned to the photosensitive drum 1 (hereinafter referred to as a primary transfer simultaneous cleaning method). The primary transfer simultaneous cleaning method has an advantage that a throughput is not reduced because a cleaning step is not particularly required.

Further, as shown in FIG. 6, a transfer residual developer collecting member 8 may be provided.

The transfer residual developer collecting member 8 is also a metal roll,
Various forms such as an elastic roll having conductivity, a fur brush having conductivity, and a blade having conductivity can be adopted.

A voltage having a polarity opposite to that of the voltage applied to the cleaning charging member 7 is applied to the transfer residual developer collecting member 8 so that the transfer residual developer can be electrostatically cleaned.

In the apparatus of FIG. 6, for example, when the power is turned on, a bias having a polarity opposite to that of the photosensitive drum 1 is applied to the transfer residual developer recovery member 8 to transfer residual development in the transfer residual developer recovery container 9. It is also possible to charge the agent and collect it in the photosensitive drum cleaning device 13. This method has an advantage that the transfer residual developer collecting container 9 can be downsized.

[0027]

However, are these color electrophotographic devices fully functioning as the above-mentioned advantages and functioning as a device that truly expects and satisfies users? That is no. When the image forming apparatus using this intermediate transfer member is actually repeatedly used, it still has the following problems to be overcome.

Various materials are used for the intermediate transfer belt, but in the case of a so-called plastic belt, due to durability,
Although the change in the length is small, stress cracking easily occurs due to durability, and it is difficult to extend the life. Further, in the case of a rubber belt, although stress cracking due to endurance is small, when it is endured, elongation occurs and image shift easily occurs. As a countermeasure against this, a highly durable belt can be made by inserting a highly durable core material into the rubber belt. However, by inserting this core, the distance between the core and the core is 0.1 m on the surface of the rubber belt.
Waviness may occur at a cycle of about 3 mm from m. When the surface of the rubber belt is polished, this waviness occurs due to a difference in hardness between a portion having a core and a portion having no core at the time of polishing, but the cause is not limited to this. Also, when using paint on the surface layer for both belt and drum shapes, wrinkles may occur on the surface when the drying speed of the outermost surface is high and the internal drying speed is slow in the drying process. The waviness may occur in a cycle of about 0.1 mm to 3 mm. When these undulations occur on the intermediate transfer body, the transfer efficiency of the convex portion of the surface undulation of the intermediate transfer body is high at the time of transferring the toner image on the photosensitive drum of the first color when a four-color full-color image is output. The density is high only in the convex portion, and unevenness occurs in the image. Next, at the time of transferring the second color to the intermediate transfer body, the portion where the second color toner image is not superimposed on the first color toner image and the portion where the first color toner image is on the intermediate transfer body are exposed to light. At the time of contact with the drum, a phenomenon (hereinafter referred to as retransfer) in which a part of the toner on the intermediate transfer body returns to the photosensitive drum may occur (this phenomenon occurs when the primary transfer voltage is high). However, the toner on the convex portions of the surface waviness of the intermediate transfer body may return to the photosensitive drum more than the concave portions, and the image density of the convex portions may decrease. Further, when the toner image of the second color is added to the toner image of the first color, the transfer of the toner image of the second color is hindered by the retransfer of the convex portion of the first color, and the image density of the convex portion becomes low. There is. The same phenomenon occurs in the third and fourth colors, and when the image is finally transferred from the intermediate transfer member to the second image carrier (paper or the like), the convex portion has a low density,
An image with a high density is formed in the recessed portion, and image unevenness equivalent to the shape of the core part (hereinafter referred to as core mark) or image unevenness equivalent to the shape of the surface scratch (hereinafter referred to as “crinkle mark”) may occur. there were.

Although the above description is based on the intermediate transfer member having the core and the coating conditions, it goes without saying that the core is not provided or the surface is formed by coating. Even if not, if the finally obtained surface has the same surface waviness as described above, the same phenomenon may occur.

Further, since the transfer residue from the second image carrier for the recessed part is the recessed part, when the cleaning step for returning the transfer residue to the photosensitive drum is performed, the transfer part returns to the photosensitive drum from the protruding part. It is difficult and insufficiently cleaned, and a large load is applied to the apparatus for cleaning a large amount of transfer residual toner, which makes the cleaning apparatus considerably complicated in structure and expensive. was there.

As measures against these, for example, Japanese Patent Laid-Open No. 59-5.
0475, JP-A-59-202477, JP-A-3-24
2667, JP-A-4-303869 and JP-A-4-30
As can be seen in Japanese Patent No. 3871, an intermediate transfer member having a reduced surface roughness is considered, but this surface roughness corresponds to the surface of toner particles, and in the case of the above-mentioned waviness condition, the surface Even if the roughness was reduced, core marks or crack marks could sometimes occur.

The present invention proposes an image forming apparatus using an intermediate transfer member that solves the above problems.

That is, when the toner moves from the surface of the photosensitive drum, which is the first image carrier, to the intermediate transfer member, there is no image unevenness in the undulation portion, and at the time of retransfer when outputting a multicolor image. (EN) An image forming apparatus which does not increase the amount of retransfer of a waviness convex portion and does not generate a core mark or a scratch mark of an image finally obtained.

[0034]

That is, according to the present invention, an image formed by transferring an image formed on a first image bearing member onto an intermediate transfer member and then further transferring it onto a second image bearing member. In the apparatus, the image forming apparatus is characterized in that the intermediate transfer member has an average surface waviness of a wavelength of 0.1 mm or more and less than 3 mm, and the average wave height of the surface waviness is 10 μm or less.

In the present invention, the surface waviness of the surface of the intermediate transfer member, that is, the average wave height of the surface waviness of the intermediate transfer member having an average surface waviness of a wavelength of 0.1 mm or more and less than 3 mm is set to 10 μm or less. The difference in the distance that the toner moves from the surface of the photosensitive drum, which is the image carrier 1 to the intermediate transfer member, reduces the difference between the convex portion and the concave portion of the undulation of the intermediate transfer member. Is reduced, and the core marks are reduced by eliminating the retransfer of the convex portion at the time of the second primary transfer, and the core trace is eliminated by eliminating the transfer inhibition due to the retransfer of the convex portion. By reducing the number, defective cleaning due to the toner remaining in the concave portion after the secondary transfer is reduced.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Surface waviness on the surface of an intermediate transfer member,
That is, the average wave height of the surface waviness of the intermediate transfer member having an average surface waviness of 0.1 mm or more and less than 3 mm is 10 μm.
The following effects can be obtained, but preferably 5
μm or less. Also, the core trace or the Chijimi trace is
The average wavelength of the surface waviness occurs at an average of 0.1 mm or more and less than 3 mm, but a more prominent generation region is 0.5 mm or more and less than 2.5 mm.

The surface waviness measuring method used in the present invention is measured according to JIS B0610, and the filtered centerline waviness curve is used. The average wavelength of the present invention is represented by the average interval Sm (ISO) of the irregularities of the curve obtained by the filtered centerline waviness curve, and the average wave height is the ten-point average roughness of the curve obtained by the filtered centerline waviness curve. Rz
(JIS). The low-frequency cutoff of the measurement conditions at this time is 0.08 mm, the high-frequency cutoff is 8 mm, the measurement length is 25 mm, and the measurement speed is 2 mm / s. Also,
In the above measurement, when it is desired to accurately measure undulations having a wavelength of 0.5 mm or more, the low cutoff is 0.25 mm, the high cutoff is 8 mm, the measurement length is 25 mm, and the measurement speed is 2 mm / s. .

As a method of reducing the average wave height of the surface waviness of the intermediate transfer member, surface grinding of the intermediate transfer member, in the case of an intermediate transfer member having an elastic layer, surface grinding of the elastic layer, and for surface portions For example, the humidity of the atmosphere is adjusted when the paint is applied.

When the surface of the intermediate transfer member is ground or the surface of the elastic layer is ground, there are a grinder, a lapping device, a belt grinding method, a barrel processing method and the like.

As a method for reducing the surface waviness of the first image carrier, the above-mentioned methods are the main methods, but of course the method is not limited to this.

When adjusting the coating atmosphere at the time of coating the coating material for the surface of the intermediate transfer member, the humidity is preferably 45% RH or more. If it is less than 45 RH%, the drying speed of the paint surface becomes faster, and the difference in drying speed between the surface portion and the inside may appear, which may worsen the surface waviness, and the average of 0.1 mm or more which is the object of the present invention. The average wave height of the surface waviness of the intermediate transfer member having a surface waviness of less than 3 mm is 10 μm.
It becomes difficult to set the thickness to m or less.

Rubber, elastomer, and resin used in the elastic layer and the coating layer of the intermediate transfer member used in the present invention, for example, rubber, and as the elastomer, natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber. , Ethylene-propylene rubber, ethylene-propylene terpolymer, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylonitrile butadiene rubber, urethane rubber, syndiotactic 1,2-polybutadiene, epichlorohydrin rubber, acrylic rubber, silicone rubber , Fluororubber,
Polysulfide rubber, polynorbornene rubber, hydrogenated nitrile rubber and thermoplastic elastomers (for example, polystyrene,
One or more selected from the group consisting of polyolefins, polyvinyl chlorides, polyurethanes, polyamides, polyesters, fluororesins, etc.) can be used. However, it is not limited to the above materials.

As the resin, polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer is used. Copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer and styrene-acrylic Acid phenyl copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α- Methyl chloroacrylate copolymer, styrene-acryloni Styrene resins such as tolyl-acrylic acid ester copolymers (styrene or homopolymers containing styrene substitution products), methyl methacrylate resins, butyl methacrylate resins, ethyl acrylate resins, butyl acrylate resins, Modified acrylic resin (silicone modified acrylic resin, vinyl chloride resin modified acrylic resin and acrylic / urethane resin, etc.), vinyl chloride resin, styrene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, rosin modified maleic acid resin, Phenolic resin, epoxy resin, polyester resin, polyester polyurethane resin, polyethylene, polypropylene,
Polybutadiene, polyvinylidene chloride, ionomer resin, polyurethane resin, silicone resin, fluorine resin,
Ketone resin, ethylene-ethyl acrylate copolymer,
One or more selected from the group consisting of xylene resin, polyvinyl butyral resin, polyamide resin, modified polyphenylene oxide resin, and the like can be used. However, it is not limited to the above materials.

A conductive agent may be added to adjust the resistance value of the intermediate transfer member used in the present invention. The conductive agent is not particularly limited. For example, carbon, metal powder such as aluminum and nickel, metal oxide such as titanium oxide, quaternary ammonium salt-containing polymethyl methacrylate, polyvinyl aniline, polyvinyl pyrrole, and polydiamine One or more kinds selected from the group consisting of acetylene, polyethyleneimine, boron-containing polymer compounds, and conductive polymer compounds such as polypyrrole can be used. However, it is not limited to the above conductive agent.

The intermediate transfer member used in the present invention has a roller shape other than the belt shape, for example, a roller shape having an elastic layer made of at least rubber, elastomer or resin on a cylindrical conductive support, and further, its elasticity. A roller shape having one or more coating layers on top of the layers can also be selected as required.

As the cylindrical conductive support, a metal or alloy such as aluminum, iron, copper and stainless, a conductive resin having carbon or metal particles dispersed therein, or the like can be used, and the shape thereof is as described above. Such a cylindrical shape, a shape in which a shaft penetrates through the center of the cylinder, a shape in which the inside of the cylinder is reinforced, and the like can be mentioned.

The thickness of the intermediate transfer belt is preferably as thick as possible so that the belt can be smoothly driven, and is preferably thin as long as the mechanical strength and flexibility of the belt are not impaired. Specifically, 0.1 to 2 mm is preferable. Further, when providing a coating layer provided on the core layer,
The thickness of the outermost layer is preferably as thin as possible without impairing the flexibility of the coating layer thereunder, specifically, 1 to 500.
μm, and more preferably 5 to 200 μm.

The film thickness of the elastic layer as the intermediate transfer drum is 0.5 mm or more, more preferably 1 mm or more, and particularly 1 mm to
It is preferably 10 mm. Further, the film thickness of the coating layer is preferably a thin layer for transmitting the flexibility of the lower elastic layer to the upper layer thereabove or the surface of the photoreceptor,
Specifically 3 mm or less, further 2 mm or less, especially 20
It is preferably μm to 1 mm.

The material forming the core used in the intermediate transfer belt is, for example, natural fiber such as cotton, silk, hemp and wool; regenerated fiber such as chitin fiber, alginic acid fiber and regenerated cellulose fiber; acetate fiber and the like. Semi-synthetic fiber, polyester fiber, nylon fiber, acrylic fiber, polyolefin fiber, polyvinyl alcohol fiber, polyvinyl chloride fiber, polyvinylidene chloride fiber, polyurethane fiber,
Synthetic fibers such as polyalkylparaoxybenzoate fibers, polyacetal fibers, aramid fibers, polyfluoroethylene fibers and phenol fibers; inorganic fibers such as carbon fibers, glass fibers and boron fibers; metal fibers such as iron fibers and copper fibers One kind or two or more kinds selected can be used. However, of course, the material is not limited to the above. The role of the core layer in the present invention is to improve the mechanical strength of the intermediate transfer belt. As a specific form of the core layer, as shown in FIGS. 3 to 5, woven cloth, non-woven cloth, thread or film can be considered.

The thickness of the core layer in the present invention means
When the core layer is a woven or non-woven fabric, the woven or non-woven fabric in a state before being formed into an intermediate transfer belt is used.
It refers to a value measured with a thickness measuring instrument TH-102 (manufactured by Tester Sangyo Co., Ltd.).

When the core layer has a thread shape, the thickness of the thread is the thickness of the core layer. Regarding the thickness of the yarn, the yarn in the state before being formed into the intermediate transfer belt is measured by the above thickness measuring machine.

Further, when the core layer is in the form of a film, the value of the film thickness measured by the above thickness measuring machine is taken as the thickness of the core layer. However, if it is impossible to measure with a thickness measuring machine, cut the intermediate transfer belt in the thickness direction,
The value observed with a microscope or the like is defined as the thickness of the core layer.

When the form of the core layer does not correspond to any of the above, the intermediate transfer belt is cut in the thickness direction,
The value observed with a microscope or the like is defined as the thickness of the core layer.

From the viewpoints of easiness of production and production cost, a preferable example of the form of the core is a woven fabric or a thread as shown in FIGS. 3 and 4.

The yarn may be a single filament or a plurality of twisted filaments.
Any twisting method such as a plied yarn and a twin yarn may be used. Further, for example, fibers of the materials shown in the above material group may be blended. Further, in some cases, the yarn may be subjected to an appropriate conductive treatment before use.

Similarly, as the woven fabric, any woven fabric such as knitted fabric can be used, and, of course, a mixed woven fabric can also be used. In some cases, the woven fabric may be used after being subjected to an appropriate conductive treatment.

The method of manufacturing the core is not particularly limited, but for example, a method of covering a metal mold or the like with a woven fabric woven into a cylinder and providing a coating layer thereon, or a woven fabric woven into a cylinder Examples thereof include a method of immersing in a liquid rubber or the like to form a coating layer on one or both sides of the core layer, a method of spirally winding a thread around a mold or the like at an arbitrary pitch, and providing a coating layer thereon. .

The purpose of providing the core on the intermediate transfer member used in the image forming apparatus of the present invention is to reinforce the intermediate transfer belt. Therefore, the thickness of the core is arbitrary, but a preferable range is 10 to 500 μm. The thickness of the core is 10
If it is less than μm, the reinforcing effect becomes small and the original purpose cannot be achieved. If it is thicker than 500 μm, the rigidity of the core increases and it becomes difficult to smoothly drive the intermediate transfer belt, which is not preferable.

The volume resistivity of the intermediate transfer member used in the present invention is preferably 10 ¹ to 10 ¹³ Ω · cm, and particularly preferably 10 ² to 10 ¹⁰ Ω · cm.
Further, at least the volume resistivity of the surface layer is preferably within these ranges.

The photosensitive drum, which is the first image bearing member used in the present invention, has, for example, an organic photosensitive layer provided on a conductive support and, if necessary, has a barrier function and an adhesive function between them. Some have a subbing layer.

As a characteristic of such an organic photoconductor, it is often used as the first image carrier because of its high safety, good chargeability, good productivity and low cost.

As the first electroconductive support for image carrier used in the present invention, for example, the following ones can be used.

(1) Aluminum, aluminum alloys,
Metals such as stainless steel and copper.

(2) By vapor-depositing or laminating a metal such as aluminum, palladium, rhodium, gold or platinum on the surface of the non-conductive support such as glass, resin and paper or the conductive support of the above (1) Formed thin film.

(3) A layer of a conductive polymer, a conductive compound such as tin oxide and indium oxide, is formed on the surface of the non-conductive support such as glass, resin and paper or the conductive support of the above (1). Formed by vapor deposition or coating.

As the material for forming the undercoat layer, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, methyl cellulose, casein, polyamide, glue and gelatin are usually used.

The organic photosensitive layer comprises 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 resin and coating this on a conductive support. Further, the thin film can be formed on the conductive support by a dry method such as vapor deposition, sputtering and 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.

(1) Azo pigments such as monoazo, bisazo and trisazo (2) Indigo pigments such as indigo and thioindigo (3) Phthalocyanine pigments such as metal phthalocyanine and non-metal phthalocyanine (4) Perylene anhydride and perylene Perylene pigments such as acid imides (5) Polycyclic quinone pigments such as anthraquinone and hydroquinone (6) Squarylium dye (7) Pyrylium salts and thiopyrylium salts (8) Triphenylmethane dyes

The binder resin can be selected from a wide range of binder resins, for example, polycarbonate resin, polyester resin, polyacrylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, Examples thereof include, but are not limited to, vinyl acetate resin, phenol resin, silicone resin, polysulfone resin, styrene-butadiene copolymer resin, alkyd resin, epoxy resin, urea resin and vinyl chloride-vinyl acetate copolymer resin. 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 the resin contained in the charge generation layer is 80% by weight or less, preferably 40% by weight or less. Also,
The thickness of the charge generation layer is 5 μm or less, particularly 0.01 μm to 2
It is preferable that the thin film layer has a thickness of μm. Various sensitizers may be further added to the charge generation layer.

The charge generating layer is formed by coating and drying a paint in which a charge transporting 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 and triarylmethane compounds. Further, as the binder resin, those mentioned above can be used. For coating the organic photosensitive layer, any of conventionally known methods such as a dipping method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method and a roll coating method can be used.

Further, when an OPC photosensitive drum containing fine powder of tetrafluoroethylene resin (PTFE) in the outermost layer of the photosensitive drum is used, high primary transfer efficiency can be obtained.

[0075]

Embodiments will be described below.

Example 1 (Preparation of Compound for Elastic Layer) SBR 33 parts (parts by weight, the same applies hereinafter), EPDM 67 parts, vulcanizing agent (precipitated sulfur) 1.5 parts, vulcanization aid (zinc 2 parts, vulcanization accelerator (MBT) 1 part, vulcanization accelerator (TMTM) 1.2 parts, conductive carbon black 25 parts, stearic acid 1 part and plasticizer (naphthene-based process oil) 40 parts, Was mixed with two rolls for 20 minutes while cooling to prepare a compound.

(Preparation of rubber belt) A rubber compound having the above composition was uniformly wound around a cylindrical mold with a thickness of 0.45 mm. Next, a nylon thread (diameter 100 μm) having an adhesive coated on the surface thereof was used to form a pitch of 1.
It was spirally wound at 5 mm. A rubber compound having the following composition extruded into a tube shape was covered thereon and vulcanized at 150 ° C. for 50 minutes to prepare an elastic tube.

(Grinding and lapping of rubber belt surface)
The rubber belt prepared above was ground with a grinding wheel. The surface waviness at this time is the average wavelength (Sm value)
The average wave height (Rz) was 1.497 mm and 20 μm. From this state, lapping was further performed using a # 800 abrasive paper with a lapping device. The surface waviness at this time was almost the same as the average wavelength (Sm value) of 1.498 mm, but the average wave height (Rz) was 7 μm and the waviness height decreased. The resulting rubber belt has an elastic layer with a thickness of 0.35 mm above the core and a thickness of 0.45 below the core.
It had an elastic layer of mm.

(Preparation of coating material for coating layer) 100 parts of polyurethane prepolymer, 4 parts of isocyanate, 0.04 of catalyst
Parts, PTFE powder (particle size 0.3 μm) 71 parts, dispersion aid 4 parts, MEK 400 parts and N-methylpyrrolidone 50
The parts were mixed to prepare a coating material for the coating layer.

(Preparation of Intermediate Transfer Member) The coating material for the coating layer was spray-coated on a rubber belt. At this time, the temperature of the coating atmosphere was 25 ° C. and the humidity was 60% RH. After coating, after drying for 1 hour in the same atmosphere as the coating atmosphere, the residual solvent was removed by heating at 120 ° C for 2 hours, and the coating was crosslinked to form a tough coating layer (thickness: 30 μm). Outer layer)
An intermediate transfer belt having The resistance value of the obtained intermediate transfer belt was 1.5 × 10 ⁸ Ω.

The surface waviness of this intermediate transfer belt was equal to the average wavelength (Sm value) of 1.501 mm, which was equivalent to the wavelength of the base layer, but the average wave height (Rz) was 4.9 μm, and the waviness height was higher than that of the base layer. A reduced belt was obtained. The surface roughness of the belt surface was measured according to JIS B0601 under the conditions of a measurement length of 2.5 mm, a cutoff of 0.8 mm, and a measurement speed of 0.5 mm / s. Is 0.7 μm, and the ten-point average roughness (R
z) was 4.1 μm, and a belt having a small surface roughness value was obtained.

(Image forming conditions) Color developer (for all four colors): Non-magnetic one-component toner Primary transfer voltage: + 500V Secondary transfer voltage: + 1500V Process speed: 120 mm / sec (Evaluation of intermediate transfer belt) This intermediate transfer The belt was attached to the full-color electrophotographic apparatus shown in FIG.
^{When a} full-color image was printed on ^two papers, no trace of cores equivalent to the wavelength interval on the belt surface was seen, and a good image was obtained.

The cleaning method for the intermediate transfer belt is the simultaneous primary transfer cleaning method using an elastic roller having a resistance of 1 × 10 ⁸ (Ω) for the cleaning charging member 7, and the cleaning charging member 7 is charged by the bias power source 26. The current value applied to the member 7 was set to +40 (μA), but since the intermediate transfer belt had a small waviness concave portion, no toner remained in the concave portion even during cleaning, and the cleaning property was good.

Example 2 (Preparation of Compound for Elastic Layer) Same as Example 1 (Preparation of Rubber Belt) Same as Example 1 (Grinding of Rubber Belt Surface) The rubber belt prepared above was ground by a grinding stone. went. The surface waviness at this time was an average wavelength (Sm value) of 1.497 mm, and the average wave height (Rz) was 20 μm. The rubber belt obtained as a result had an elastic layer having a thickness of 0.35 mm on the core and an elastic layer having a thickness of 0.45 mm under the core.

(Preparation of coating material for coating layer) Same as in Example 1 (Preparation of intermediate transfer member) The coating material for coating layer was spray-coated on a rubber belt. The temperature of the coating atmosphere at this time is 25
The temperature and humidity were 60% RH. After coating, after drying for 1 hour in the same atmosphere as the coating atmosphere, the residual solvent was removed by heating at 120 ° C for 2 hours, and the coating was crosslinked to form a tough coating layer (thickness: 30 μm). An intermediate transfer belt having an outer layer) was obtained.

The surface waviness of this intermediate transfer belt was 1.500 mm, which was equal to the average wavelength (Sm value), which was equivalent to the wavelength of the base layer, but the average wave height (Rz) was 13.2 μm and the waviness height was high. It was From this state, lapping was further performed using a # 800 abrasive paper and then lapping was performed using a # 2000 abrasive paper. As a result, the surface waviness of the finally obtained intermediate transfer member was almost unchanged at an average wavelength (Sm value) of 1.502 mm, but the average wave height (Rz) was 4.7 μm, which was a decrease in waviness height. The resulting rubber belt has an elastic layer with a thickness of 0.35 mm above the core and a thickness of 0.45 mm below the core.
Had an elastic layer. The surface roughness of the belt surface is measured according to JIS B0601 with a measurement length of 2.5 mm, a cutoff of 0.8 mm and a measurement speed of 0.5 m.
When measured under the condition of m / s, the center line surface roughness (R
a) is 0.4 μm and the ten-point average roughness (Rz) is 4.5.
A belt having a thickness of μm and a small surface roughness value was obtained.
The resistance value of the obtained intermediate transfer belt was 1.8 × 10 ⁸ Ω.

(Image forming conditions) Same as in Example 1 (Evaluation of intermediate transfer belt) This intermediate transfer belt was mounted on the full-color electrophotographic apparatus shown in FIG.
^When a full-color image was printed on No. ² , no traces of cores equivalent to the wavelength interval on the belt surface were seen, and a good image was obtained.

[0088] The cleaning method of the intermediate transfer belt, a primary transfer-cleaning scheme using an elastic roller in cleaning charging member 7 has a resistance of 1 × 10 ⁸ (Ω), the charging cleaning from a bias power source 26 The current value applied to the member 7 was set to +40 (μA), but since the intermediate transfer belt had a small waviness concave portion, no toner remained in the concave portion even during cleaning, and the cleaning property was good.

[Example 3] (Adjustment of compound for elastic layer) 100 parts of EPDM,
4.5 parts of zinc oxide, 1 part of higher fatty acid, 6 parts of conductive carbon black, 10 parts of paraffin oil, 2 parts of sulfur, 1 part of vulcanization accelerator MBT, 1.5 parts of vulcanization accelerator TMTD and vulcanization accelerator. A compound was prepared by mixing 1.5 parts of ZnMDC for 20 minutes while cooling with two rolls.

(Preparation of coating material for coating layer) 100 parts of polyurethane elastomer, 41 parts of conductive titanium oxide Dispersion aid 1
2 parts, tetrafluoroethylene resin powder (particle size 0.3 μm) 2
50 parts and DMF 1200 parts were mixed and the coating material for 2nd layer was prepared.

(Preparation and Evaluation of Intermediate Transfer Drum) Diameter 18
A rubber roller having an elastic layer was obtained by first transfer molding and vulcanizing an elastic layer compound on the surface of an aluminum cylindrical roller having a length of 2 mm, a length of 320 mm and a thickness of 5 mm using a mold. Next, the coating material for the coating layer was spray-coated on this. At this time, the temperature of the coating atmosphere was 23 ° C. and the humidity was 55% RH. After coating, after drying for 1 hour in the same atmosphere as the coating atmosphere, 12
The residual solvent was removed by heating at 0 ° C. for 2 hours to obtain an intermediate transfer drum having a coating layer (outermost layer) having a thickness of 50 μm. The surface waviness of this intermediate transfer belt was 45% RH or more in the coating atmosphere, so the average wavelength (Sm value)
It was 0.35 mm, and the average wave height (Rz) was 5.3 μm, and the belt had a low waviness height.

This intermediate transfer member was heated at a temperature of 23 ° C. and a humidity of 65%.
Under the environment, the transfer surface of the intermediate transfer member is placed in contact with the aluminum plate of 350 mm × 200 mm, and a voltage of 1 kV is applied by a high voltage power supply between the aluminum cylinder and the aluminum plate on the inner surface of the intermediate transfer member. The potential difference before and after the 1 kΩ resistor connected in series was measured and converted into a current value, and the resistance value of the intermediate transfer member was calculated from the applied voltage (1 kV) and this current value. It was ⁷ Ω.

(Image forming conditions) Color developer (for all four colors): Non-magnetic one-component toner Primary transfer voltage: + 100V Secondary transfer voltage: + 1500V Process speed: 120 mm / sec (Evaluation of intermediate transfer drum) This intermediate transfer The belt is attached to the full-color electrophotographic apparatus shown in FIG.
^{When a} full-color image was printed on ^two papers, a fine image similar to the wavelength interval on the belt surface was not seen, and a good image was obtained. In FIG. 2, 25 is a transfer roller, 30 is an intermediate transfer drum, 31 is a cylindrical conductive support, 32 is an elastic layer,
33 is a coating layer, 35 is a paper feed cassette, 38 is a bias power supply, and 62 is a bias power supply.

[0094] The cleaning method of the intermediate transfer drum, a primary transfer-cleaning scheme using an elastic roller in cleaning charging member 7 has a resistance of 1 × 10 ⁸ (Ω), the charging cleaning from a bias power source 26 The current value applied to the member 7 was +40 (μA), but since the intermediate transfer drum had a small waviness concave portion, no toner remained in the concave portion even during cleaning, and the cleaning property was good.

Comparative Example 1 (Preparation of Compound for Elastic Layer) Same as Example 1 (Preparation of Rubber Belt) Same as Example 1 (Grinding of Rubber Belt Surface) The rubber belt prepared above was ground with a grinding stone. went. At this time, the surface waviness was 1.498 mm in average wavelength (Sm value), and the average wave height (Rz) was 20.2 μm. The rubber belt obtained as a result has an elastic layer with a thickness of 0.35 mm on the core,
It had an elastic layer having a thickness of 0.45 mm under the core.

(Preparation of coating material for coating layer) Same as in Example 1 (Preparation of intermediate transfer member) The coating material for coating layer was spray-coated on a rubber belt. The temperature of the coating atmosphere at this time is 25
The temperature and humidity were 60% RH. After coating, after drying for 1 hour in the same atmosphere as the coating atmosphere, the residual solvent was removed by heating at 120 ° C for 2 hours, and the coating was crosslinked to form a tough coating layer (thickness: 30 μm). An intermediate transfer belt having an outer layer) was obtained.

The surface waviness of this intermediate transfer belt was an average wavelength (Sm value) of 1.496 mm, which was equivalent to the wavelength of the base layer, but the average wave height (Rz) was 13.8 μm, which was a high waviness belt. It was The surface roughness of this belt is measured according to JIS B0601, and the measured length is 2.5 m.
When measured under the conditions of m, cutoff 0.8 mm, and measurement speed 0.5 mm / s, the center line surface roughness (Ra) is
The ten-point average roughness (Rz) was 0.6 μm, and a belt having a small surface roughness value was obtained. The resistance value of the obtained intermediate transfer belt was 1.8 × 10 ⁸ Ω.

(Image forming conditions) Same as in Example 1 (Evaluation of intermediate transfer belt) This intermediate transfer belt was mounted on the full-color electrophotographic apparatus shown in FIG.
^{When a} full-color image was printed on ^two papers, since the wave height of the belt surface waviness was larger than 10 μm, core marks equivalent to the wavelength interval were generated even though the surface roughness was small, resulting in a defective image.

The cleaning method for the intermediate transfer belt is the simultaneous primary transfer cleaning method using an elastic roller having a resistance of 1 × 10 ⁸ (Ω) for the cleaning charging member 7, and the cleaning charging member 7 is charged by the bias power source 26. The current value applied to the member 7 was +40 (μA), but the residual toner remained in the concave portions during cleaning due to the corrugated concave portions, resulting in poor cleaning.

Comparative Example 2 (Adjustment of Compound for Elastic Layer) Same as Example 2 (Preparation of coating material for coating layer) Same as Example 2 (Preparation and evaluation of intermediate transfer drum) Diameter 182 mm, length 320 mm, First, a rubber roller having an elastic layer was obtained by transfer-molding and vulcanizing the compound for elastic layer using a mold on the surface of a cylindrical roller made of aluminum having a thickness of 5 mm. Next, the coating material for the coating layer was spray-coated on this. The temperature of the coating atmosphere at this time is 23 ° C,
Humidity was 5% RH. After coating, after drying for 1 hour in the same atmosphere as the coating atmosphere, the residual solvent was removed by heating at 120 ° C. for 2 hours to obtain an intermediate transfer drum having a coating layer (outermost layer) with a thickness of 50 μm. It was The surface waviness of this intermediate transfer belt had a coating atmosphere of 5% RH, so wrinkles and wrinkles occurred on the surface, and the average wavelength (Sm value)
0.75mm, average wave height (Rz) 18.3μm
The belt has a high swell.

This intermediate transfer member was heated at a temperature of 23 ° C. and a humidity of 65%.
Under the environment, the transfer surface of the intermediate transfer member is placed in contact with the aluminum plate of 350 mm × 200 mm, and a voltage of 1 kV is applied by a high voltage power supply between the aluminum cylinder and the aluminum plate on the inner surface of the intermediate transfer member. The potential difference before and after the 1 kΩ resistor connected in series was measured and converted into a current value, and the resistance value of the intermediate transfer member was calculated from the applied voltage (1 kV) and this current value. 3.8 × 10 It was ⁷ Ω.

(Image forming conditions) Same as in Example 3 (Evaluation of intermediate transfer drum) This intermediate transfer belt was mounted on the full-color electrophotographic apparatus shown in FIG.
^{When a} full-color image was printed on ² papers, the wave height of the belt surface waviness was larger than 10 μm, so that a wrinkle mark equivalent to the wrinkle wavelength interval due to wrinkle wrinkles was generated and a defective image was obtained.

The cleaning method of the intermediate transfer drum is the simultaneous primary transfer cleaning method using an elastic roller having a resistance of 1 × 10 ⁸ (Ω) as the cleaning charging member 7, and the cleaning power is charged from the bias power source 26. The current value applied to the member 7 was +40 (μA), but the residual toner remained in the concave portions during cleaning due to the corrugated concave portions, resulting in poor cleaning.

[0104]

As described above, according to the present invention, the average wave height of the surface waviness of the intermediate transfer member having the surface waviness of the wavelength of 0.1 mm or more and less than 3 mm on average is 10 μm or less. As a result, traces of the core and cracks due to the waviness on the surface will not occur, and
The cleaning failure due to the toner remaining in the concave portion after the next transfer does not occur.

Therefore, even when the image forming apparatus using the intermediate transfer member is actually used, it is possible to always obtain a uniform image.

[Brief description of drawings]

FIG. 1 is a schematic view of a color image output device using an intermediate transfer belt.

FIG. 2 is a schematic diagram of a color image output device using an intermediate transfer drum.

FIG. 3 is a schematic view of a part of a base layer of the intermediate transfer belt of the present invention having a woven cloth core layer.

FIG. 4 is a schematic view of a part of a base layer of the intermediate transfer belt of the present invention having a filamentous core layer.

FIG. 5 is a schematic view of a part of a base layer of the intermediate transfer belt of the present invention having a film-shaped core layer.

FIG. 6 is a schematic diagram of a color image output device using an intermediate transfer belt.

[Explanation of symbols]

 1 Photosensitive Drum 2 Primary Charger 3 Image Exposure Means 7 Cleaning Charging Member 8 Transfer Residual Developer Collection Member 9 Transfer Residual Developer Collection Container 10 Transfer Material Guide 11 Paper Feed Roller 13 Photosensitive Drum Cleaning Device 15 Fixer 20 Intermediate Transfer belt 21 Covering layer 22 Core layer 23 Covering layer 24 Transfer material 25 Transfer roller 26 Bias power supply 27 Bias power supply 28 Bias power supply 29 Bias power supply 30 Intermediate transfer drum 31 Cylindrical conductive support 32 Elastic layer 33 Covering layer 35 Paper feeding Cassette 38 Bias power source 41 Yellow color developing device 42 Magenta color developing device 43 Cyan color developing device 44 Black color developing device 61 Roller 62 Bias power source 63 Secondary transfer roller 64 Secondary transfer opposing roller

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Akihiko Nakazawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akira Shimada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Minoru Shimojo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hiroyuki Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (7)

[Claims] 1. An image forming apparatus for transferring an image formed on a first image bearing member onto an intermediate transferring member and then further transferring it onto a second image bearing member, wherein the intermediate transferring member has an average of 0. Having a surface waviness of a wavelength of 1 mm or more and less than 3 mm,
An image forming apparatus, wherein the average wave height of the surface waviness is 10 μm or less. 2. The image forming apparatus according to claim 1, wherein the intermediate transfer member has an elastic layer and one or more coating layers. 3. The image forming apparatus according to claim 1, wherein the elastic layer has a core body. 4. The image forming apparatus according to claim 2, wherein the coating layer is formed by coating. 5. The image forming apparatus according to claim 1, wherein the first image carrier is an organic photoconductor. 6. The first image carrier is a photosensitive drum having a photosensitive layer on a conductive rigid roller, and at least the outermost layer of the photosensitive drum contains fine powder of tetrafluoroethylene resin. Item 6. The image forming apparatus according to any one of items 1 to 5. 7. The image forming apparatus cleans the intermediate transfer member by applying a charge to a transfer residual developer not transferred from the intermediate transfer member to the second image carrier by using a cleaning charging member. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.