JPH07146617A - Image transfer method - Google Patents

Abstract

PURPOSE:To improve transfer performance in the case of transferring from an intermediate transfer body to a body to be transferred by transferring a toner image in a state where an intermediate transfer medium is substantially destaticized when the toner image is transferred to the body to be transferred. CONSTITUTION:A photoreceptor drum 1 consisting of an organic photoconductor having infrared sensitivity in an electrophotographic printer is rotated in a direction shown by an arrow and its surface is electrified to be positive by a corona charger 2. A transfer drum 6 having a surface to which the transfer sheet is wound and attached comes in contact with the photoreceptor in a state where its surface is electrified to be negative on the transfer sheet by a corona charger 8, and toner is transferred to the transfer drum by its electrostatic field force. After transfer, the electrifying charge on the surface of the transfer drum 6 is destaticized by an AC destaticizer 9 before the drum 6 comes in contact with an impression cylinder drum 10. Thereafter, the toner which has lost electrostatic attractive force is fixed on a paper surface in a state where it is softened by heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transferring a toner image formed by an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

[0002]

2. Description of the Related Art As a method of transferring a toner image on an image bearing member to a transferred member, a method of directly transferring from the image bearing member onto the transferred member, or a method of transferring the toner image to an intermediate surface and then transferring it again Then there is a method of making the final image. In terms of the quality of the finally obtained image, the method of performing transfer via an intermediate transfer body is generally good. However, the use of the intermediate transfer member has not been put to practical use except for some dry copying machines because of the problem that the machine becomes large, the failure rate, the cost, and the maintainability. However, the use of the intermediate transfer member is highly necessary in applications where image quality is important, particularly when an image is formed by a liquid developing method.

As a method for transferring the toner on the surface of the photosensitive member to the surface of the intermediate transfer member, the adhesiveness of the intermediate transfer member itself is utilized, or at the same time, an electrostatic electric field is applied to transfer the toner. When most of the toner image is transferred, and then the toner on the surface of the intermediate transfer member is transferred to the surface of the final transfer target, the toner is melted or softened by heating and then transferred to the transfer target. Depending on the contacting method, the toner is peeled off from the surface of the intermediate transfer member to transfer the toner. As the intermediate transfer member, a heat-resistant polyamide-imide resin film such as Kapton (trade name of DuPont) is used as a support, and silicone rubber or silicone A resin layer is provided.

Considering electrostatic transfer at the time of transferring the toner image on the photoreceptor, an electric field is applied from the back surface of the support film, or a conductive layer is provided between the silicone rubber layer and the support. It creates an electric field and performs electrostatic transfer,
Both are methods of applying an electric field to the intermediate transfer member itself.
This method has a problem in that an electrostatic field is applied even when the toner image is retransferred to the final transfer target, which gives a negative transfer effect, which hinders complete transfer.

[0005]

An object of the present invention is to improve transferability when transferring from an intermediate transfer member to a transfer target, which is a problem in the electrophotographic method for performing the intermediate transfer as described above. Especially.

[0006]

The present invention provides a method for transferring a toner image on an image bearing member to an intermediate transfer medium, and further transferring the toner image from the intermediate transfer medium to a transfer target,
A voltage is applied to the intermediate transfer medium when the toner image on the image carrier is transferred to the intermediate transfer medium, and the intermediate transfer medium is transferred in a state of being substantially discharged when transferring the toner image on the intermediate transfer medium. Image transfer method. That is, the toner image formed on the surface of the image carrier is transferred by the electrostatic charge force charged on the surface of the intermediate transfer medium, and after transfer, the charge is removed and transferred to the transfer medium. The present invention relates to an image transfer method.

In order to transfer the toner image from the image bearing member to the intermediate transfer member, the surface of the intermediate transfer member is charged by corona charging or the like before the transfer, and AC is transferred after the transfer (before the transfer to the transfer target).
Alternatively, the charge is eliminated by light or the like, and when the image is transferred to the transfer target, the surface of the intermediate transfer is transferred with substantially no electric charge. Embodiment 1 Hereinafter, the present invention will be described with reference to the drawings. Reference numeral 1 denotes a photoconductor drum made of an organic photoconductor having infrared sensitivity in an electrophotographic printer. The photoconductor drum 1 rotates in a direction of an arrow and its surface is negatively charged by a corona charger 2. Three
Is infrared laser writing light, which scans and exposes an image to form an electrostatic latent image. Reference numeral 4 denotes a liquid developing device, in which the latent image is visualized by toner adhesion. Reference numeral 6 is an intermediate transfer drum, and a transfer sheet 7 in which a room temperature vulcanized silicone rubber according to RTV615 manufactured by General Electric Co. is applied to a thickness of 50 μm on a 100 μm-thick Kapton film is wound around and mounted on the surface.

The transfer drum 6 contacts the photoconductor while the surface of the transfer sheet is positively charged on the transfer sheet by the corona charger 8, and the toner is transferred to the transfer drum by its electrostatic field force. After the transfer, before the contact with the impression drum 10, the AC static eliminator 9 removes the electric charge on the surface of the transfer drum. After that, the toner having lost the electrostatic attraction is fixed on the paper surface while being softened by heat. Compared to the case where a voltage is directly applied to the transfer drum 6, the residual toner on the transfer sheet is reduced and the reproduction stability of transfer is increased. In particular, the transfer efficiency of halftone dots of 20% or less was improved. From this, it was confirmed that the life of the transfer sheet due to the remaining toner can withstand the use of about 5,000 times to 30,000 times or more. Example 21 1 is a photosensitive drum made of an organic photoconductor having infrared sensitivity in an electrophotographic printer, which is rotated in the direction of the arrow and its surface is positively charged by a corona charger 2. Reference numeral 3 denotes infrared laser writing light, which scans and exposes an image to form an electrostatic latent image. Reference numeral 4 denotes a liquid developing device, in which the latent image is visualized by toner adhesion. An intermediate transfer drum 6 is a transfer sheet 8 in which 200 μm NBR rubber including a foam layer is applied on 100 μm cotton cloth, and silicone rubber by RTV3140 manufactured by Dow Corning Co., Ltd. is applied to a thickness of 50 μm on the surface. It is wound around and installed.

The transfer drum 6 contacts the photosensitive member while the surface of the transfer sheet is negatively charged on the transfer sheet by the corona charger 8, and the toner is transferred to the transfer drum by its electrostatic field force. After the transfer, before the contact with the impression drum 10, the AC static eliminator 9 removes the electric charge on the surface of the transfer drum. After that, the toner having lost the electrostatic attraction is fixed on the paper surface while being softened by heat. Compared to the case where a voltage is directly applied to the transfer drum 6, the residual toner on the transfer sheet is reduced and the reproduction stability of transfer is increased. As a result, the life of the transfer sheet due to the remaining toner is reduced from 5,000 times to 20,
It was confirmed that it could be used more than 000 times.

[0010]

According to the image transfer method of the intermediate transfer member of the present invention, the force of electrostatic charge does not affect the transfer to the transfer target member, so that the final transfer efficiency is improved, and the toner on the intermediate transfer sheet is accompanied by it. The remaining amount was reduced and the life of the intermediate transfer sheet could be extended.

[Brief description of drawings]

FIG. 1 is an explanatory view (schematic cross-sectional view) showing an embodiment of the present invention in the configuration of a wet laser printer. (Explanation of symbols) 1. Photoconductor drum 2. Corona charger 3. Laser writing light 4. Liquid developer 5. Coating adjustment roller 6. Intermediate transfer drum 7. Intermediate transfer sheet 8. Corona charger 9. AC static eliminator 10. Impression roller

Claims (1)

[Claims] 1. A method for transferring a toner image on an image carrier to an intermediate transfer medium, and further transferring the toner image from the intermediate transfer medium to a transfer medium, wherein the toner image on the image carrier is transferred to the intermediate transfer medium. The image transfer method is characterized in that a voltage is applied to the intermediate transfer medium during the transfer, and the transfer is performed in a state where the intermediate transfer medium is substantially neutralized when transferring the transfer target.