JPS63298264A - Transfer material separating device - Google Patents

Abstract

PURPOSE:To always execute a stable separation in spite of a difference of a separation characteristics of a transfer material, and a variation of the environment by providing a separating belt for separating a separating electrifier and the end edge of the transfer material, on the downstream side of a transfer part in the running direction of the transfer material. CONSTITUTION:It is supposed that a toner image on the surface of a photosensi tive body 1 is transferred to a transfer material by an operation of a transfer electrifier 3. After the transfer, the transfer material advances as it is and reaches a position of a separating electrifier 4, destaticized by the separating electrifier 4, and thereafter, separated from the photosensitive body 1 by elastic ity and dead weight of the transfer material itself, and further advances, and fed to a fixing part by a carrying member 6. In this case, in a position where the transfer and the separating electrifiers 3, 4, exist, a separating belt 5 is provided in the advance direction of the transfer material, and also, so as to run along one end edge. In such a way, in spite of a difference of a characteristics of the transfer material, and a variation of the environment, a satisfactory separation can be executed without generating a separation fail ure, a retransfer, etc.

Description

Detailed Description of the Invention (1) Object of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus that uses an electrostatic recording process, such as an electrostatic copying machine or a printer, and particularly to a transfer material separation device thereof. It is something.

(Prior art and issues to be solved) Transferable toner images formed on the surface of a moving image carrier
It is configured to bring a sheet-like transfer material such as paper into contact with it and run it in synchronization with the image carrier, and to electrostatically transfer the toner image to the transfer material by imparting an appropriate polar charge to the transfer material. Such image forming apparatuses have been well known.

In such image forming apparatuses, due to the charge applied to the transfer material during transfer, the transfer material tends to stick to the image carrier even after transfer, which can cause malfunctions such as jams. It is necessary to actively separate the transfer material from the image carrier.

As such a transfer material separation means, for example, a separation charger is disposed at a position after transfer, and a charge with a polarity opposite to that at the time of transfer is applied to the transfer material to neutralize and eliminate the charge at the time of transfer. Thereafter, the transfer material may be peeled off from the image carrier by its own elasticity or weight, or the image carrier or the transfer material may be separated from the image carrier at one end of the traveling transfer material or in a portion outside the image area. A medium-thin separation belt extending in the running direction of the transfer material is arranged such that a part of the belt contacts the image carrier at the transfer site and moves away from the image carrier as it goes downstream as viewed in the transfer material running direction. Arranged.

At the transfer site, the transfer material comes into contact with the image carrier without hindering image formation, and after the transfer, one edge of the transfer material separates from the image carrier along the belt, and as a result, the entire transfer material A so-called separation belt system has already been proposed, in which the parts are separated one after another, each with a certain amount of parts. It is also widely used for practical purposes.

However, the former separation means is, for example, a transfer material with low elasticity such as a lightweight paper weighing 50 grams or less, moisture-absorbed paper, or an image carrier whose tip is usually formed into a cylindrical shape. When paper or the like that is curled in the direction along the surface of the paper is used as a transfer material, jams may occur due to poor separation, or the corona discharge current for one separation may deviate from the allowable range, causing retransfer. In the case of the latter type of separation belt type, when using the transfer material described above, only the side where the separation belt is present will separate.
Other parts may not be separated, resulting in poor separation as a whole and jams may occur, or even if it does not go that far, the transfer material may be irregularly curved or distorted during separation. There is a risk that the image may be distorted or the toner may fall from the transfer material and contaminate various parts within the apparatus.

The present invention has been made in order to cope with such a situation, and an object of the present invention is to provide a separation device that can always perform good separation regardless of the environment or the characteristics of the paper used as the transfer material. It is.

(2) Structure of the invention (technical means for solving the problem, its operation) In order to achieve the above objects, the present invention provides a method for separating and charging a transfer material as a transfer material separation means in an image forming apparatus that utilizes an electrostatic recording process. There is a method characterized by using a container and a separation belt, and in which the separation belt is configured so that it can selectively take a position where it acts on the transfer material and a position where it does not act on the transfer material.

With this configuration, poor separation can be avoided regardless of differences in the characteristics of the transfer materials or changes in the environment.

Good separation can be performed at all times without causing retransfer.

(Description of Embodiments) FIG. 1 is a side view of essential parts showing an embodiment in which the present invention is applied to a copying machine equipped with a rotating cylindrical photoreceptor, which extends in the direction perpendicular to the plane of the paper and in the direction indicated by the arrow. A transfer charger 3 is disposed parallel to the rotating photoreceptor 1, and a separation charger 4 is disposed adjacent thereto.

A transferable toner image formed on the surface of a photoreceptor.

When the photoreceptor rotates and reaches the transfer site with the transfer charger 3, a sheet-like transfer material (not shown) such as paper is guided by the conveyance member 2 and moved in the direction of arrow B at the same timing. It is assumed that the toner image advances to the transfer site, comes into contact with the toner image on the surface of the photoreceptor, and the toner image is transferred to the transfer material by the action of the transfer charger.

After the transfer, the transfer material advances as it is until it reaches the position of the separation charger 4. After being neutralized by the separation charger 4, the transfer material is separated from the photoreceptor by its own elasticity and weight, and then advances further and is transported. It is assumed that the member 6 is fed to a fixing site (not shown).

In such a device, a separation belt 5 is disposed in the direction of movement of the transfer material and along one edge of the transfer material at a position where the transfer 1 separation charger is present.

The separation belt 5 has an end located on the upstream side, as viewed in the traveling direction of the transfer material, attached to the conveying member or other appropriate immovable part,
Since the transfer charger 3 is in contact with the photoconductor 1 at a certain transfer site, at this position, most of the center of the conveyed transfer material is in contact with the toner image on the photoconductor, but the edges thereof are in contact with the toner image on the photoconductor. The portion outside the image area is located below the separation belt in the figure, and after transfer, the edge portion advances along the separation belt and gradually separates from the photoreceptor, and along with this, other portions of the transfer material also move away from the photoreceptor. It is forced to separate from the photoreceptor one after another.

With this structure, as mentioned above, even with thin paper, moisture-absorbing paper, curled paper, etc., which have a small opening property, the adsorption effect on the photoconductor is weakened by the static elimination effect of the separation charger 4. By separating only one edge, it is possible to easily separate the other parts, and even in cases where separation failure occurs due to insufficient charge removal by the separation charger, separation failure can be avoided. never occurs,
At the same time, this reduces the possibility of retransfer due to excessive charge removal, and can prevent the inconvenience of retransfer from occurring.

The table below shows the occurrence of retransfer and separation defects according to the present invention when thin paper with a weight of 42 gr/m'' is used and the charger 1 separation belt is used individually.

Table As is well known in the past, the discharge current of a separation charger formed by superimposing direct current on alternating current can be maintained without causing poor separation or re-transfer, regardless of environmental changes or the separation characteristics of the transfer material. In order to maintain stability, it is necessary to take a large amount of change in the DC component, and the mechanism for this has to become large and complicated, but as can be seen from the table above, the present invention can be applied. By doing so, it is possible to expand the allowable range of the discharge current of the separation charger, especially in the direction of insufficient static removal, so that a stable separation function can be maintained at all times against the attenuation and fluctuation of the separation corona discharge. Can be done.

FIG. 2 is a side view of main parts showing another embodiment of the present invention.

In this case, the downstream end of the one-separation belt 5a in the direction in which the transfer material travels is pulled by a spring 7, so that an appropriate tension is applied to the separation belt.

With this configuration, the 1-separation belt can use an extremely thin film member such as polyester or polyethylene, and the presence of the belt can cause the transfer material at the transfer site to curve or cause the portion that directly contacts the photoreceptor. It is possible to avoid a situation where a local change in synchronization of the advancing speed occurs due to a difference in the frictional action between the transfer material and the transfer material, causing distortion of the transfer material and deterioration of image quality.

FIG. 3 is a perspective view of essential parts showing another embodiment of the present invention.

In the figure, the photoreceptor is indicated by a one-dot chain line, and the area on its surface where the transfer material is present is indicated by a two-dot chain line.

When the separation bell 5b is at the position indicated by the solid line in the figure, it overlaps the area where the transfer material is present, and therefore, when the transfer material passes through the transfer site, one edge thereof is below the belt. After the transfer, the image moves along the belt and gradually separates from the photoreceptor.

In such a case, as shown, the separation bell)
5b is provided with an appropriate belt release member such as a solenoid 8, and a separation bell (separation bell) 5b as required.
It is configured such that it can be displaced from an operating position shown by a solid line to an inoperative position shown by a dotted line.

With this structure, when using thick transfer material that can be easily separated, dry transfer material, etc., the separation belt can be placed in the inactive position to ensure that the entire surface of the transfer material is brought into close contact with the photoreceptor. The separation belt can be used only for transfer materials that are difficult to separate, such as thin paper.

First of all, thick transfer materials are usually stiff, so while they have good separation properties, when a separation belt is used, the edge (the side where the separation belt is located) may overlap the image area. However, according to the present invention, such a situation can be effectively avoided.

Although an embodiment in which the present invention is applied to a copying machine equipped with a rotating cylindrical photoreceptor has been described above, the present invention is not limited thereto, and may be applied to other image carriers or other types of image forming apparatuses. It is easy to understand that it can also be applied to

(3) Effects of the Invention As explained above, the present invention uses a separation charger and a separation belt to separate a transfer material from an image carrier in an image forming apparatus that uses an electrostatic transfer process. Since the structure is such that both of them work together to separate the transfer material,
Regardless of the separation characteristics of the transfer material or environmental changes, it is possible to perform stable separation at all times without causing poor separation or retransfer, which greatly contributes to obtaining high-quality images.

Furthermore, by making the separation belt move forward and backward with respect to its operating position, images without image defects can be obtained.

[Brief explanation of drawings]

Fig. 1 is a side view of the main parts showing an embodiment in which the present invention is applied to a copying machine, Fig. 2 is a side view of another embodiment similar to the above, and Fig. 3 is a side view of the main parts showing an example of application of the present invention. be. DESCRIPTION OF SYMBOLS 1...Photoreceptor, 2e...Transporting member, 3...Transfer charger, 4*Φ*Separation charger, 5.5a, 5b-...Separation belt. Figure 1 Figure 2 j

Claims (3)

[Claims] (1) In an image forming apparatus that electrostatically transfers a transferable toner image formed on the surface of a traveling image carrier to a transfer material traveling synchronously with the image carrier, the transfer site is A transfer material separation device comprising a separation charger and a separation belt for separating the edges of the transfer material on the downstream side. (2) The transfer material separation device according to claim 1, further comprising means for applying tension so as to press the separation belt against the image carrier. (3) In an image forming apparatus that electrostatically transfers a transferable toner image formed on the surface of a traveling image carrier to a transfer material traveling in synchronization with the image carrier, the transfer site is means for arranging a separation charger and a separation belt for separating the edges of the transfer material on the downstream side, and selecting an operating position for separating the transfer material and a non-operation position for separating the separation belt from the transfer material; A transfer material separation device comprising means for displacing the material.