JPH03188474A - Guide rib of electrifying device - Google Patents

Abstract

PURPOSE:To improve discharging effect while maintaining strength of a guide rib by setting the guide rib inclined so that a shadow cast on a photosensitive drum related to the discharge is made small. CONSTITUTION:The guide rib 37 is formed in a twisted state where it is extended inclined in a direction separating from the photosensitive drum 20 as it is extended to a down stream side of a direction X against the tangent line direction of the photosensitive drum 20 going through a straight line A connecting a center O1 of the photosensitive drum 20 and a wire 36. Here, the wire 36 is placed in a position on a dotted line, and concerning corona discharge generated from the wire 36, the shadow to the visual point position is made the minimum. Even when the visual point is deviated in the X direction or in an inverse X direction, since the side surface of the guide rib 37 is made parallel with the line of sight in a part where the line of sight of the direction of the wire 36 is passed, the shadow formed by the guide rib 37 is always made the minimum. Thus, a discharging effect with good efficiency can be realized while maintaining its strength.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a method for charging a photoreceptor drum, which is attached to a charging device having a wire for performing corona discharge toward a photoreceptor drum, and in which a transfer sheet is inserted into the charging device. The present invention relates to a guide rib for a charging device that prevents this.

[Conventional technology]

Conventionally, a separation charger used as a charging device to charge a photoreceptor drum of an electronic image processing device such as an electrophotographic copying machine or a laser beam printer has a case and an AC voltage placed inside the case. It includes a wire to which an electric voltage is applied and a plurality of guide ribs arranged to cover the wire. The guide ribs are arranged at intervals in the width direction of the transfer paper, and are arranged in a V-shape so as to move away from the center of the charger toward the downstream side in the conveyance direction of the transfer paper.

In the separation charger, an AC voltage is applied to the wire to apply an AC voltage to the transfer paper attached to the photoreceptor drum.
Corona discharge takes place. As a result, the corona charge on the back surface of the transfer paper generated in the transfer process is neutralized, and the transfer paper is peeled off from the drum surface. The guide ribs guide the transfer paper so that the separated paper does not enter the case of the separation charger. In addition, the guide ribs are
Since the separating charger is arranged so as to spread out in a V-shape toward the downstream side with respect to the center of the separation charger, the separated paper is subjected to a force in a direction of being stretched as it is guided by the guide ribs. As a result, the transfer paper is conveyed in a flat state toward the fixing section.

[Problem to be solved by the invention]

In the conventional separation charger, the side surfaces of the guide ribs are vertical surfaces. However, the wire is generally placed downstream of the center of the photoreceptor drum in the paper conveyance direction. Therefore, as shown in FIG. 7, a straight line connecting the center of the photoconductor drum 1 and the wire 2 (the
The guide rib 3 is inclined if the line connecting the shortest distance between the two is used as a reference. As a result of the guide rib 3 being inclined at the portion where the separation effect is most effective, the shadow of the guide rib 3 on the photoreceptor drum 1 related to the discharge from the wire 2 becomes larger by the amount of the inclination. In the conventional configuration, the shadow of the guide ribs 3 is large, making it impossible to achieve an efficient separation effect.

On the other hand, it is conceivable to downsize the guide rib in order to reduce the shadow of the guide rib, but in that case, a problem arises in that the strength of the guide rib decreases.

An object of the present invention is to provide a guide rib for a charging device that can maintain the strength of the guide rib, reduce the shadow of the guide rib regarding discharge, and realize efficient discharge action.

[Means to solve the problem]

The guide rib of the charging device according to the present invention is attached to a charging device having a wire for performing corona discharge toward the photoreceptor drum, and is a charging device that prevents transfer paper from entering the charging device. It is a guide rib. The guide ribs are twisted so that the shadow cast on the photoreceptor drum by discharge from the wire is reduced.

[Effect]

In the guide rib of the charging device according to the present invention, the transfer paper peeled off from the surface of the photoreceptor drum is moved on the guide rib toward the fixing unit.

Here, the guide ribs are twisted by degrees ζ so that the shadow cast on the photoreceptor drum by discharge from the wire is reduced. Therefore, without downsizing the guide rib,
The shadow of the guide ribs on the photoreceptor drum 11 can be reduced. As a result, an efficient discharge effect can be obtained while maintaining the strength of the guide ribs.

〔Example〕

FIG. 2 shows an example of a copying machine employing an embodiment of the present invention.

In FIG. 2, a document table 12 is provided on the top surface of the copying machine main body 11.
is fixed, and a document holder 1 is mounted on the top of the document table 12.
3 is attached so that it can be opened and closed freely.

On the right side of the copying machine main body 11 are paper feed cassettes 14 and 15.
is attached removably. A paper discharge tray 18 is mounted on the left side of the copying machine main body 11, from which copied sheets are discharged.

Inside the copying machine main body 11, an exposure device 19 for reading originals is provided at the upper part thereof.

This exposure device f19 is composed of a light source, a mirror, and the like. Further, a photosensitive drum 20 on which an electrostatic latent image is formed is arranged in the center of the copying machine main body 11. Around the photoreceptor drum 20, there is a main charger 21 that charges the photoreceptor drum 20 to a predetermined charge, a developing device 22 that develops the electrostatic latent image, and a transfer charger that transfers the toner image onto paper. A cleaning device 25 is arranged to remove residual toner on the container 23 and the photosensitive drum 20°. On the downstream side of the transfer charger 23, a separation charger 24 as a charging device is arranged adjacent to the transfer charger 23.

This separation charger 24 is for separating the paper from the photoreceptor drum 20.

Between the paper feed cassette 14, 15 and the image forming unit 1O constituted by the photosensitive drum 20, etc., and the image forming unit 1
A paper feed conveyance path 27 and a paper discharge conveyance path 28 are provided on the downstream side of 0, respectively, for conveying paper. A fixing device 30 is arranged between the paper discharge conveyance path 28 and the paper discharge tray 18 to fix the transferred image on the conveyed paper.

The transfer charger 23 and the separation charger 24 are members extending parallel to the center line of the photoreceptor drum 20, and are integrally formed with each other as shown in FIGS. 3 and 4. At both ends of the vessels 23 and 24, as shown in FIG.
A pair of housings 31 and 32 are arranged. A metal shield case 33 having an opening at its upper end is arranged between both housings 31 and 32. shield case 3
3 has a partition plate 34 in the center as shown in FIG.
ζ, thereby dividing the transfer charger 23 side and the separation charger 24 side.

In the shield case 33 on the side of the transfer charger 23, a tungsten wire 35 to which a DC voltage is applied for performing a transfer operation is arranged. The wire 35 extends parallel to the centerline of the photoreceptor drum 20 and is supported at both ends by the housing 31.32. On the other hand, the wire 35 is also inside the shield case 33 on the side of the separation charger 24.
A tungsten wire 36 is arranged parallel to the tungsten wire 36 . An alternating current voltage is applied to the wire 36, thereby neutralizing the corona charge on the back side of the °C transfer paper, thereby allowing the transfer paper to be separated.

A guide rib 37 is provided at the opening of the shield case 33 on the separation charger 24 side, and guides the transfer paper separated from the photoreceptor drum 20 onto the paper discharge conveyance path 28 (
(Fig. 2). One end of each guide rib 37 is formed integrally with a holder 38, and the holder 38 is fixed to the shield case 33. Further, as shown in FIG. 3, the guide ribs 37 are arranged so as to spread out in a V-shape as they go downstream in the transfer paper conveyance direction (downstream in the direction of arrow X) with the center of the separation charger 24 as a reference. has been done. Further, as shown in FIG. 4, the guide rib 37 guides the paper peeled from the photoreceptor drum 20 in the X direction, so that the photoreceptor drum 20 passes through the straight line A connecting the center 01 of the photoreceptor drum 20 and the wire 36. With respect to the tangential direction of , as it goes downstream in the X direction, it extends in a direction that is inclined away from the photoreceptor drum 20 .

The guide rib 37 extends from the holder 38 in the reverse X direction, as shown in FIG. The holder 38 is fitted into the shield case 33 on the side of the separation charger 24 (the fourth
(see figure), thereby positioning the guide rib 37. Furthermore, the guide ribs 37 are formed in a twisted state as shown in FIG. Here, when viewed in the direction of FIG. 1, the wire 36 is placed at the position indicated by the dashed-dotted line, and the shadow on the viewpoint position of the electric discharge generated from the wire 36 is the smallest. Moreover, since the guide rib 37 is formed in a twisted state as shown in FIG. 1, even if the viewpoint is shifted in the X direction or the reverse is parallel to the line of sight as shown in FIG. 5, so the shadow formed by the guide rib 37 is always minimized. That is, as a result of the twisted guide rib 37, the shadow of the guide rib 37 on the surface of the photoreceptor drum 20 with respect to the corona discharge generated from the wire 36 is always minimized.

Next, the operation of the above embodiment will be explained.

In FIG. 2, the paper from the paper feed cassette 14 or 15 passes through the paper feed conveyance path 27 and is conveyed to the image forming section IO. On the other hand, image information of the original on the original platen 12 is transferred onto the photoreceptor drum 20 as an electrostatic latent image by the optical system 19. The electrostatic latent image on the photosensitive drum 20 is transferred to a developing device 22.
Developed by The developed toner image is then transferred onto the paper by the transfer device 23.

The paper on which the image has been transferred is peeled off from the photosensitive drum 20 by the separation charger 24 and guided to the paper discharge conveyance path 28 side. The peeling operation by this separation charger 24 is as follows:
It is based on an AC corona discharge caused by an AC voltage applied to the wire 36 of the separation charger 24. This corona discharge neutralizes the corona charge on the back surface of the transfer paper, and the transfer paper is peeled off from the surface of the drum 20. At this time, since the guide ribs 37 are twisted as shown in FIG. 1, the shadow formed by the guide ribs 37 on the photosensitive drum 20 regarding corona discharge is always minimized (see FIG. 5). Since the shielding area of the corona discharge by the guide ribs 37 becomes smaller, the peeling effect on the transfer paper is high.In other words, the guide ribs 37 can be reduced in size without being
The separation effect by the separation charger 24 is improved.

In addition, in the embodiment, the guide rib 37 is connected to the wire 36.
and the center O1 of the photoreceptor drum 20 at a position intersecting with a straight line A (FIG. 4).

However, the present invention is not limited to such an arrangement; for example, the guide rib 37 may be arranged at a position that does not intersect with the straight line A on the downstream side in the X direction.

In the above embodiment, the method of peeling the transfer paper from the surface of the photoreceptor drum was taken as an example, and the guide rib was not attached to the separation charger. However, the present invention is not limited thereto; for example, if the present invention is applied to a type that does not include a separation charger and peels the transfer paper from the photoreceptor drum by a so-called curvature separation method, the guide ribs can be used as the charging device. Each time it is attached to this transfer charger.

〔Effect of the invention〕

According to the guide rib of the charging device according to the present invention, the guide rib is set to be inclined so that the shadow on the photoreceptor drum related to discharge is small. can be improved.

[Brief explanation of drawings]

FIG. 1 is a partial plan view of an embodiment of the present invention, FIG. 2 is a schematic vertical cross-sectional view of a copying machine in which an embodiment of the present invention is adopted, and FIG. A perspective partial view, FIG. 4 is an enlarged schematic view of the vicinity of the separation charger in FIG. 2, and FIG.
-■ Partial cross-sectional view, FIG. 6 is a diagram corresponding to FIG. 5 of the conventional example. 10... Image forming section, 20... Photosensitive drum, 24
...Separation charger, 33...Shield gate, 36
...wire, 37...guide rib.

Claims (1)

[Claims] (1) A guide rib of a charging device that is attached to a charging device having a wire for performing corona discharge toward the photoreceptor drum and is used to prevent transfer paper from entering the charging device, the guide rib is a guide rib of a charging device that is twisted so that a shadow cast on the photoreceptor drum due to discharge from the wire is reduced;