JPS641025B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying apparatus that transfers a toner image on a charge carrier to a transfer material via an intermediate transfer belt.

Generally, the process of image formation using an electrophotographic device involves forming an electrostatic latent image corresponding to the image of a document on a charge holding body using an insulating photoconductor as a photoconductor by corona charging and light irradiation. A visible image is formed by developing this with a developer containing thermoplastic colored fine powder as a main component. The visible image, or toner image, on this charge carrier is transferred onto a copying material, such as transfer paper, by an electrical transfer method such as corona discharge or a bias roller, or by physical means such as pressing or heating. Ru.

The toner image transferred onto the transfer paper by the above method is fixed onto the transfer paper by a conventional heating means, and the image forming process is completed.

As described in the image forming process above, electric methods such as a corona discharge transfer method or a bias roller transfer method are generally known as methods for transferring the toner image formed on the charge carrier to a transfer paper or the like. However, this method has many problems, such as a low transfer rate and disturbances in the transferred image, especially in humid environments, so other methods that do not rely on electrical means are being considered. A transfer method using pressure has also been reported as one of the methods. For example, according to the description in Japanese Patent Publication No. 46-41679, the toner image on the photoreceptor is wrapped in an elastic, heat-resistant intermediate bracket, and the toner image on the photoreceptor is transferred without leaving any residue. A method and apparatus for producing high quality image transfer is described.

When an intermediate transfer body is used as a transfer medium in this way, a blanket or belt whose surface is a rubber-like elastic material that has some degree of adhesion to toner powder and is heat resistant is generally used. be made available for use.

As the substrate for the blanket or intermediate transfer belt, metal sheets or drums or resins such as polyimide, polyester, fluorine resin films or drums are used from the viewpoint of heat resistance, tensile strength, flatness, adhesion of the transfer layer, etc. etc. are suitable for use, and the basic structure is completed by providing silicone rubber, fluorine rubber, etc. as a transfer layer on these substrates.

The toner image formed on the charge carrier by charging, exposure, and development comes into contact with the surface of the intermediate transfer belt at the transfer position, and is physically transferred to the surface of the intermediate transfer belt by being strongly pressed by a pressure roller or the like. Ru. After the toner image is transferred, when the charge carrier and the intermediate transfer belt rotate together and pass the transfer position where strong pressure is applied, the strong pressure is released and the elastic transfer layer of the intermediate transfer belt returns to its original state. However, at this time, it is charged due to separation from the surface of the charge carrier. This charging not only impairs safety but also adversely affects the image quality of the transferred image.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a copying apparatus that uses a belt transfer member with improved charging properties to transfer a toner image on a charge carrier to a transfer material.

The above-mentioned object of the present invention is a copying apparatus that forms a toner image on a charge carrier through charging, exposure, and development, transfers it by pressing it against an intermediate transfer belt at a transfer position, and then transfers and fixes it onto a transfer material by heat and pressure. In the above, the intermediate transfer belt is provided with a transfer layer on a substrate, to which toner can be transferred by adhesion or pressure effect, and the thickness of the substrate is 5 to 200μ, and the thickness of the transfer layer is 20 to 200μ. can be,
This is achieved by a copying apparatus in which a conductive antistatic layer having a thickness of 0.5 to 20 μm is formed on the non-transfer surface of the intermediate transfer belt opposite to the transfer layer.

Hereinafter, a copying apparatus of the present invention will be explained based on the drawings.

1 is a charge holding drum rotating in the direction of the arrow; 1a is a charge holding body stretched over the charge holding drum 1; the charge holding body may be anything that can hold charges on its surface; For example, selenium, zinc oxide, cadmium sulfide, a photoreceptor with an organic photoconductive material on a suitable support, or an insulator with an insulating material on a suitable support. It is mentioned as a typical example. Reference numeral 2 denotes an electrostatic latent image forming section, which may be any unit as long as it can form a charge as an electrostatic latent image on the charge carrier 1a; for example, a charging device may be used to uniformly form charges on the charge carrier 1a. It may be a means for forming an electrostatic latent image by later erasing a portion of the charge by imagewise exposure, or a means for directly forming the charge as an electrostatic latent image, such as an electrostatic recording needle. 3 is a developing device for converting the electrostatic latent image formed on the charge carrier 1a into a toner image, and 4 is a cleaning device for cleaning the toner remaining on the charge carrier 1a after the toner image is transferred. device, and 5
is a static eliminator for removing the charge remaining on the charge holding member 1a after the toner image has been transferred. Reference numeral 6 denotes an intermediate transfer belt for transferring the toner image on the charge holding member 1a and transferring the toner image to a transfer material, and the side opposite to the toner image bearing surface is treated to prevent charging, as will be described later. A transfer roller 7 is disposed inside the intermediate transfer belt 6 and presses the belt against the charge carrier, and usually a rubber roller is used. 8
A transfer fixing roller is used to transfer the toner image on the intermediate transfer belt 6 to a transfer material, and has a heat source 8a built therein. 9 is a tension roller; 10 is a drive roller connected to a drive source (not shown); It has been passed. It is preferable that at least one of the rollers supporting the intermediate transfer belt 6 is electrically conductive. Reference numeral 11 denotes a transfer paper for carrying a toner image as a permanent image, and although it may be ordinary paper, for example, special paper whose surface has been treated to be insulating may also be used.
12 transfers the toner image on the intermediate transfer belt 6 to a transfer paper 1
This is a pressure roller for pressing the transfer paper 11 against the intermediate transfer belt 6 from the back surface thereof in order to transfer the transfer paper 11 to the intermediate transfer belt 6.

Next, the operation of the illustrated copying apparatus of the present invention will be explained.

The charge holding drum 1 has a charge holding body 1a on its surface.
While rotating in the direction of the arrow, an electrostatic latent image is formed in the electrostatic latent image forming section 2, and then the electrostatic latent image is developed in the developing device 3, and the charge holding drum carrying the toner image is The point of transcription is reached. At the transfer point, the intermediate transfer belt 6 driven by the drive roller 10 moves in the direction of the arrow in synchronization with the rotation of the charge holding drum 1 so as to contact the charge holding body 1a at the transfer point, and the charge is held at this transfer point. The toner image on the body 1a is transferred to the intermediate transfer belt 6 by the pressure of the transfer roller 7. Intermediate transfer belt 6 to which the toner image has been transferred
moves in the direction of the arrow and transfers the toner image onto the transfer paper 11 fed by a feeding means (not shown) by pressure contact between the transfer fixing roller 8 and the pressure roller 12, and at the same time transfers the toner image to the transfer paper 11 fed by a feeding means (not shown). Source 8
The toner image is thermally fused and fixed by step a to become a permanent image.

Although the intermediate transfer belt of the present invention may use the substrate itself as a transfer layer, it is usually a belt in which a transfer layer 62 is provided on a substrate 61 as shown in FIG. 2 in order to maintain mechanical strength. The substrate 61 is required to have excellent properties in heat resistance, tensile strength, flatness, strength (especially heat resistance strength) and adhesion of the transfer layer at high temperatures, and can be made of metal sheets, polyimide resins, polyimide amide resins, polyester resins, Examples of preferred substrates include fluororesins, and particularly polyimide resins.

The transfer layer 62 needs to be able to sufficiently transfer the toner on the charge carrier to the transfer layer by adhesive or pressure bonding effect, and to be able to further transfer the toner image onto the transfer material, especially after each transfer. Preferably, no or little toner remains on the charge carrier and on the transfer layer.

Examples of materials for the transfer layer that satisfy these properties include ordinary rubber-like substances such as natural rubber, urethane rubber, styrene-butadiene rubber, silicone rubber, and fluorocarbon rubber. In this case, silicone rubber and fluorine rubber are preferable in order to perform fixing at the same time and to prevent toner from remaining on the subsequent transfer layer. Silicone rubber is available in room temperature vulcanization type (RTV) and low temperature vulcanization type (LTV).
and high temperature vulcanization type (HTV), LTV, RTV, and silicone rubber are particularly preferred materials for the transfer layer. These silicone rubbers are known as methyl silicone rubber, methyl phenyl silicone rubber, methyl vinyl silicon rubber, methyl phenyl vinyl silicon rubber, etc.
−133WV, KE−133TV, KE−12, KE−44,
KE−1205, KE−62, KE−1300, KE−1800,
[All manufactured by Shin-Etsu Chemical Co., Ltd.], TSE-200, TSE-
201 [all manufactured by Toshiba Silicone Corporation], and Silastic 400, 401, 410, 430,
440 [manufactured by Toray Silicon Co., Ltd.].

In addition, examples of fluorocarbon rubbers include vinylidene fluoride-6-propene fluoride rubber and vinylidene fluoride-3-fluoroethylene rubber, which are Daiel G-501, G-601, and G-601.
701 [all manufactured by Daikin Industries, Ltd.], Viton A, B, C, E, LM [manufactured by DuPont],
Kel-F-Elastomer
It is commercially available as [manufactured by 3M].

In addition, fluorine-containing silicone rubber is also used as a material for the transfer layer of the present invention, and examples thereof include 1,1,1-
Examples include trifluoropropylmethylsiloxane rubber, which is commercially available as Silastic LS (manufactured by Dow Corning).

FIG. 3 shows an example of the intermediate transfer belt of the present invention. The substrate 61 and the transfer layer 62 are the same as the intermediate transfer belt shown in FIG. 2, except that 63 is an antistatic layer.
This antistatic layer 63 may be a layer of a metal sheet, a layer of conductive fine powder such as carbon black or fine metal powder dispersed in a resin, or a polymer of quaternary ammonium chlorine. It may also be a layer of conductive polymer like material. The metal sheet preferably used is a highly conductive metal such as copper, aluminum, silver, etc., and the same fine metal powder is also used. Further, as the conductive polymer, a polymer having a quaternary ammonium salt,
Ionene type polymers are used. Examples of the resin in which the conductive powder is dispersed include silicone resin, polyimide resin, polyamideimide resin, polyamide resin, thermosetting acrylic resin, thermosetting alkyd resin, polyester resin, epoxy resin, vinyl chloride resin, vinyl acetate resin, and vinyl chloride resin. Vinyl resins such as vinyl acetate copolymers and acrylic resins, and organic polymer resins such as phenolic resins are preferably used. In the present invention, resins with high heat resistance such as silicone resins, polyimide resins, polyamideimide resins, and epoxy resins are particularly preferred.

The thickness of the transfer layer of the intermediate transfer belt is preferably as small as possible as long as transfer performance is maintained, but it is usually 5μ.
The thickness of the substrate is preferably about 5 to 200 μm, with the lower limit determined by mechanical strength and the upper limit determined by thermal conductivity.

The thickness of the antistatic layer is preferably thinner, and the upper limit is determined by the conductivity and mechanical strength, and is 0.5 to 20μ.
is preferred.

Although FIG. 3 shows an example in which an antistatic layer is provided to prevent static electricity on the intermediate transfer belt, the substrate 61 in FIG. 2 contains conductive powder and conductive polymer to make the substrate itself conductive. However, in this case, the strength of the base body may deteriorate, so it is not very preferable.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a copying apparatus of the present invention, FIG. 2 is an intermediate transfer belt, and FIG. 3 is an intermediate transfer belt subjected to antistatic processing of the present invention. 1... Charge retention drum, 6... Intermediate transfer belt, 7... Transfer roller, 8... Transfer fixing roller,
61...Substrate, 62...Transfer layer, 63...Antistatic layer.

Claims (1)

[Claims] 1. In a copying apparatus that forms a toner image on a charge carrier by charging, exposing, and developing, transfers the toner image by pressing it against an intermediate transfer belt at a transfer position, and then transfers and fixes it to a transfer material by heat and pressure. is provided with a transfer layer on a substrate to which toner can be transferred by adhesion or pressure effect, the thickness of the substrate is 5 to 200μ, the thickness of the transfer layer is 20 to 200μ, and the intermediate transfer belt is A copying device characterized in that a conductive antistatic layer having a thickness of 0.5 to 20 μm is formed on the non-transfer surface opposite to the transfer layer.