JPS6281680A - Separating device - Google Patents

Abstract

PURPOSE:To make stable separation irrespective of the state of transfer material by forming a static removing needle and an insulator block integrally and placing it near a transfer charger. CONSTITUTION:A separating member 3 made by forming a insulator block 3a made of insulating synthetic resin and a static removing needle integrally is fixed to a transfer shield unit 2a. Transfer paper P that advances from guides 6a, 6b of a paper cassette to B direction comes into contact with a photosensitive boty that rotates in the direction A at a point X. At this time, charge of polarity opposite to toner is given to the paper by discharge of polarity opposite to toner is given to the paper by discharge of the discharging wire 4 of a charger 2b, and transfer is performed. When the tip of the paper P came to a position Y along a guide line 5, the high voltage of polarity opposite to the wire 4 is applied to the part 3c of the static removing needle 13b exposed to outside and the charge of the paper P is neutralized. Thus, transfer material is separated from the photosensitive body stably at all times irrespective of the state.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Purpose of the invention 1ff1 (industrial field of application) This invention relates to image forming apparatuses that utilize an electrostatic transfer process, such as electrostatic copying machines and printers, and particularly to image forming apparatuses that use the transfer material. This relates to a separation device.

(Prior art and problems to be solved) For example, as is well known in electrophotographic copying machines, a toner image electrostatically formed on the surface of an image carrier is transferred to a sheet-like transfer material mainly made of paper. , a dynamic transfer material is brought into contact with the toner image, electrostatically transferred by applying a charge of opposite polarity to that of the toner, then this transfer material is separated from the image carrier, and the transfer material is moved to a fixing site. Image forming apparatuses configured to fix and fix a toner image on a transfer material by conveying the toner image to the transfer material are conventionally well known.

Transfer material separation devices for such image forming apparatuses include, for example, mechanical separation means using separation claws or separation belts, a method of blowing air between the transfer material and the image carrier at the transfer site, and a method of separating the transfer material. The charge on the transfer material is neutralized by the suction method or by applying a charge with the opposite polarity to the transfer material at the position after transfer, and then the transfer material's own weight,
A number of methods have already been proposed, including electrostatic separation means that separate the particles using elasticity.

However, with these known methods, for example, the above-mentioned mechanical method may chip off a part of the image or damage the photosensitive layer on the surface of the image carrier, and the method that blows air or suctions the transfer material. However, there were drawbacks such as the fact that the equipment for this purpose was inevitably large.

The aforementioned silence! ``As for the separation means, it is common practice to use a separation charger to first apply a charge to the transfer material with a predetermined polarity σ, and this type of device can avoid the above-mentioned drawbacks, but Even so, an independent charger and a high-voltage power supply are required, and a considerable amount of space is required.In recent years, however, devices have been made smaller, and photoreceptors, which are usually formed in a rotating cylindrical shape, have become smaller in diameter. In view of the current situation where the space in which the image forming member is placed around the periphery has to be narrowed, this is not satisfactory in terms of cost and space.

In order to avoid such inconveniences, the present applicant attached and fixed a static elimination needle to an insulating block, and included a component with a polarity opposite to that in the transfer charger.

We proposed a method that applies a voltage lower than the voltage at which the static eliminating needle starts self-discharging.

This has made it possible to provide a small and inexpensive electrostatic separation stage, but even with such a stage,
Depending on the relative positions of the transfer charger, the static elimination side, and the insulator block that holds them, even if the bias conditions to the static elimination needle are the same, when using thin paper as the transfer material, separation performance may deteriorate. It turns out that there is something.

This is because the current flowing through the static eliminating needle is insufficient due to the relationship between the static eliminating needle, the photoconductor, and the transfer charger, or due to a difference in the impedance of the static eliminating needle and the insulator block due to the difference in the adhesion state of these members. Conceivable.

The present invention has been made in order to cope with the above-mentioned situation, and it is an object of the present invention to provide a separation device that can perform stable separation at all times regardless of the state of the transfer material.

(2) Structure of the invention (technical means for solving the problem, and its operation) In order to achieve the above object, the present invention provides a separation device disposed near a transfer charger in an image forming apparatus using an electrostatic transfer process. The device is characterized by being constructed by integrally molding a static eliminating needle and an insulator block.

With this configuration, impedance changes in the separation device portion are small, and the relative positional relationship between the transfer charger and the photoreceptor can be easily maintained in a stable state, thereby providing a stable separation effect.

(Description of the Embodiment) The attached drawing is a schematic side view of the main parts of an embodiment in which the present invention is applied to a copying machine equipped with a rotating cylindrical photoreceptor. Transfer member 2 formed in weight
and the separation member 3 are arranged to extend in the overlapping direction on the plane of the paper.

As is well known, on the fX4 edge of the photoconductor l -
A charger, a developer, a cleaner, and other various image forming means are installed, and on the right side of the figure is a cassette for storing transfer paper, which is brought one sheet at a time to the transfer site in synchronization with the toner image on the surface of the photoreceptor. On the left side of the drawing, there are a conveying means for conveying the transferred transfer paper, a fixing means, etc., but none of these are directly related to the present invention, so a description thereof will be provided. is omitted.

The lower guide 6a is taken out from a cassette (not shown), etc.
The transfer paper P guided by the upper guide 6b and traveling in the direction of the arrow B runs at the same time as the toner image (not shown) on the surface of the photoreceptor rotating in the direction of the arrow, and moves in the direction of the arrow B.
The charger 2b of the transfer member 2 contacts the photoreceptor at the point .
The discharge wire 4 starts corona discharge, and transfer is performed by applying an electric charge of opposite polarity to the toner to the transfer material P.

When the transfer material advances further and the leading edge reaches the position of symbol Y, 1
A high voltage having a polarity opposite to that of the discharge wire is applied to the static eliminating needle 3b of the separating member 3 to neutralize the electric charge on the transfer paper, so that the transfer material is separated from the photoreceptor by its own weight and its own elasticity, and is gradually removed. It progresses to a fixing site (not shown).

Note that reference numeral 5 in the figure is a guide wire stretched over the entire length in a zigzag shape, rough net shape, etc. to prevent the advancing transfer material from getting caught on the transfer member and causing a paper jam.

The separation member 3 consists of an insulating block 3a made of an insulating synthetic resin having appropriate rigidity, and a static elimination needle 3b integrally molded with the block with one end 3C exposed to the outside.

The transfer member 2 has a rectangular cross section and is composed of a shield unit 2a attached to the body of the copying machine, and a discharge unit 2b equipped with a discharge wire 4.
At a predetermined operating position, the discharge unit is pushed up by a spring (not shown), and the locking portion 2 of the shield unit
c and 2d to maintain the discharge wire in a fixed position, and the discharge unit 2b can be inserted into and removed from the copying machine in a direction perpendicular to the plane of the drawing as required.

As shown in the figure, the above-mentioned member 3 is disposed adjacent to the discharge unit 2b, and the distance l between the tip 3c of the static eliminating needle exposed to the outside and the photoreceptor provides a good separation effect. 2) and firmly adhere and fix it to the shield 2) 2a.

With this configuration, the distance between the static eliminating needle tip 3c and the photoreceptor is kept constant, and the shape of the tip is also fixed.
Since there is no possibility of contacting the insulating block or being exposed opposite to the photoreceptor, the impedance is stable and stable functions can be expected regardless of the quality of the transfer material.

The following describes the case in which the present invention is applied to a copying machine, but the present invention is not limited to this, and it goes without saying that it can be applied to image forming apparatuses other than copying machines.

(3) Effects of the Invention Since the present invention has the configuration described in 1 below, the position of the static elimination needle can be determined with high precision, and the impedance of the component can be stabilized. Good separation can always be achieved regardless of the characteristics of the

[Brief explanation of drawings]

The accompanying drawing is a schematic side view of the main parts of an embodiment in which the present invention is applied to a copying machine. l... Photoreceptor, 2... Transfer member, 3... Separation member, 4... Discharge wire, 3a... Insulating pair block, 3
b-φ・static elimination needle,

Claims (1)

[Scope of Claims] A means for electrostatically forming a toner image on the surface of an image bearing member, a sheet-shaped transfer material brought close to the toner image, and a toner image forming means for electrostatically forming a toner image on the surface of an image bearing member, and applying a charge having a polarity opposite to that of the toner to the transfer material. Image formation comprising means for transferring an image to a transfer material, and separation means for imparting a charge of the same polarity as the toner to the transfer material to neutralize the charge, thereby separating the transfer material from the image carrier. A separating device, characterized in that the separating means is formed from an insulating block made of an insulating material and a static elimination needle molded integrally with the insulating block.