JPS6256978A - Separating device - Google Patents

Abstract

PURPOSE:To perform invariably stable separating operation regardless of variation of characteristics by arranging plural discharging electrodes in a separating electrifier at equal distance from the surface of an image carrier. CONSTITUTION:The discharging wires 4a and 4b which are arranged in the separating electrifier 4 are both arranged at an equal distance l from the surface of the photosensitive body. Consequently, even is the transfer has small elasticity and does not separate from the photosensitive body smoothly after passing through a transfer part and the transfer paper moves forth as shown by a mark P2, the transfer paper is separated securely through the separating operating of the discharging wire 4b. Thus, the separating operation is performed stably at any time by extremely simple constitution without reference to the difference in characteristics of the transfer paper and variation of characteristics due to environmental changes.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus that uses an electrostatic transfer process, such as an electrophotographic copying machine or a printer, and in particular to a separation device thereof. .

(Conventional technology and issues to be solved) For the toner image formed on the photoconductive layer on the surface of the image carrier.

A sheet-shaped transfer material, mainly made of paper, is brought into contact with or in close proximity to each other, and at this position, the transfer material is charged with an opposite polarity to the toner to transfer the toner image onto the transfer material, and then the toner image is transferred to the transfer material with the same polarity as the toner. The transfer material is configured to impart a polar charge to neutralize the charge during transfer, and to separate the transfer material, which tends to stick to the image carrier due to electrostatic attraction at the transfer site, by its elasticity and own weight. Image forming apparatuses are well known in the art.

FIG. 2 schematically shows the main parts of such an apparatus, in which a transfer charger 30. A separation charger 40 is provided, and the transfer paper P is supplied from the right side in the figure through the guide path 20.
The transfer charger 30 comes into contact with the toner image formed on the surface of the image carrier at the transfer site where the transfer charger 30 is present, and at this position, the transfer paper is given a charge of opposite polarity to the toner, and the toner image is transferred to the transfer paper.

The charge applied at this time tends to attract the transfer paper to the image carrier, so a separation charger 40 is disposed downstream of the transfer charger when viewed in the running direction of the transfer paper. Charges of the same polarity are applied to eliminate the charges, and the elasticity and weight of the transfer paper separates it from the image carrier and transports it to the next step.

In this way, since the separation of the transfer paper depends on its own characteristics, it is inevitable that the separation effect will change greatly depending on the environment.In other words, when the transfer paper is well dry, its elasticity is high, so the transfer After that, the transfer paper quickly separates from the image carrier, and the transfer paper generally takes the position indicated by the symbol P1 in the figure and advances. Since the adsorption effect with the paper is relatively large, there is a risk that the paper will advance to the position P2 in the figure, and a jam may occur due to a one-separation failure.

In order to avoid such a situation, if the separation charger is equipped with two discharge wires as shown in the figure, it can be immediately thought that a large current should be passed through the wire on the downstream side. If this is done, excessive charge will inevitably be removed from the portion of the transfer paper facing the wire on the upstream side, which is undesirable as there is a risk of re-transfer.

The present invention was made in order to cope with such a situation, and an object of the present invention is to provide a separating device that can always obtain a stable separating effect regardless of changes in the characteristics of the transfer paper. .

(2) Structure of the invention (technical means for solving the problem, its effect) In order to achieve the above object, in the present invention, in a separation device equipped with a plurality of discharge electrodes, downstream electrodes are sequentially connected to an image carrier. It is characterized in that the distances from the surface are all approximately equal along the curved surface of the surface.

With this configuration, it is possible to easily separate the transfer paper, which has a strong tendency to be attracted to the image carrier, as described above.

(Description of an Embodiment) FIG. 1 shows an embodiment in which the present invention is applied to a copying machine equipped with a cylindrical image bearing member (hereinafter referred to as a photoreceptor) that rotates once. A transfer charger 3 and a separation charger 4 are arranged parallel to this.

The transfer paper P supplied from a cassette (not shown) or the like through the guide path 2 comes into contact with the photoreceptor at a transfer site where the transfer charger 3 and the photoreceptor surface face each other, and the toner already formed on the surface is removed. The image is received by the action of a transfer charger. Next, the two discharge wires 4a of the separation charger 4,
4b, the back side of the transfer paper is charged with an AC discharge and a DC discharge of the same polarity as the toner, and the charge is removed from the transfer paper to remove the adsorption effect of the transfer paper on the photoreceptor, The transfer paper is separated from the photoreceptor by its own elasticity and weight and is fed to the next fixing site.

It should be noted that, as is well known, there are, of course, disposed around the photoreceptor the members necessary for image formation, such as a charging device, a developing device, and a cleaning device, but these are not included in the present invention. Since they are not directly related, their explanation will be omitted.

According to one aspect of the present invention in the above-mentioned copying machine, the discharge wires 4a and 4b arranged in the separation charger 4 are arranged so as to be at the same distance l from the surface of the photoreceptor. .

Because of this structure, the elasticity of the transfer paper is small,
Even if the transfer paper that has passed through the transfer site does not separate from the photoreceptor immediately and progresses as shown by the symbol P2 in FIG. 1, the separation action of the discharge wire 4b works to ensure that it is separated. Become.

When the transfer paper is in a state where it has high elasticity.

As described above, the transfer paper will quickly separate and move approximately in the direction of Pi in the figure, and a large current will be supplied from the discharge wire 4b, but at this position the transfer paper has already been sufficiently separated. Therefore, no retransfer phenomenon occurs.

Although the present invention has been described above with respect to a copying machine having a separating device equipped with two wires, the present invention is not limited to this, and can also be applied to a copying machine having a separating device equipped with three or more wires. It is easy to understand that it can be applied to other image forming apparatuses as well.

Further, the image carrier may have a surface insulating layer, and the electrode is not limited to a corona wire, but may also be a needle-like object, a brush-like object, or the like.

(3) Effects of the invention Since the present invention has the configuration described above,
Due to its extremely simple structure, it is possible to always produce a stable separation effect regardless of differences in the characteristics of the transfer paper or changes in characteristics due to changes in the environment, and is extremely effective in improving work efficiency.

[Brief explanation of drawings]

Figure m1 is a side view of the main parts of an embodiment in which the present invention is applied to a copying machine, and Figure 2 is a side view showing the configuration of a known device. 1.10... Photoreceptor, 2.20... Guide path, 3.
30...Transfer charger, 4.4o/Φ/separation charger, 1
Number... Transfer paper.

Claims (1)

[Scope of Claims] A separation device that brings a toner image on the surface of an image carrier into contact with a sheet-like transfer material and transfers it to the transfer material, and then separates the transfer material from the image carrier by a separation charger, comprising: A separation device in which a plurality of discharge electrodes are arranged in a separation charger, and each electrode is arranged at the same distance from the surface of an image carrier.