JPH0627824A - Separation charger - Google Patents

Abstract

PURPOSE:To obtain a charger where jamming processing is easily performed and there is no fear that an electrode wire is cut by providing a protective member installed in a state where the specified part of an aperture part is still opened in order to prevent paper from getting into a shield case main body from the aperture part. CONSTITUTION:In the case the paper is caught by a separation pawl when it is fed to the separation pawl, for example, it is bent because it is fed by the rotation of a transfer drum further, and jamming occurs while the paper is wrinkled. Since the protective member 4 is provided at the aperture part 5 of the separation charger 8a on the outside of the transfer drum, the paper is prevented from being bent and getting into the inside of the shield case main body 1. Therefore, there is no fear that the electrode wire 2 is cut. Since the surface of the paper is moved along the edge of the member 4 in the case the transfer drum is drawn out this side to remove the jammed paper, it is easily drawn out without being caught by the upper surface 3b of a front housing 3, and jamming processing is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separation charger provided in an image forming apparatus such as a copying machine or a printer for separating a sheet from a transfer drum.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, for example, in a copying machine using a transfer drum 7, a photosensitive drum 20 is provided in contact with the transfer drum 7.
A transfer charger 21 that transfers the toner to the sheet is provided in the transfer drum 7 facing 0. A registration roller 22 and a guide plate 23 for feeding the paper to the transfer drum 7 are provided on the upstream side of the transfer charger 21, and for separating the electrostatically adsorbed paper from the transfer drum 7 on the downstream side, A separation charger device 8 composed of a pair of separation chargers is provided. Further, a separation claw 24 for separating the paper from the transfer drum 7 is provided on the downstream side thereof, a conveyor belt 25 for conveying the paper is provided on the downstream side of the separation claw 24, and the toner on the paper is thermally fixed on the downstream side thereof. A fixing device 26 and the like are provided.

When a copying operation is performed in the copying machine having the above-described structure, first, an electrostatic latent image is formed on the photosensitive drum 20 by exposure, and the electrostatic latent image is further developed by a developing device (not shown). ) To develop a toner image. On the other hand, the sheet is conveyed from the registration roller 22 to the transfer drum 7 via the guide plate 23. The conveyed paper is fixed at its front end to a stay (not shown) provided on the transfer drum 7, and is wound around the transfer drum 7 as the transfer drum 7 rotates. Next, when the sheet on the transfer drum 7 is sent to the contact portion with the photosensitive drum 20, the toner image on the photosensitive drum 20 is transferred onto the sheet by the transfer charger 21. The sheet is electrostatically attracted to the transfer drum 7 by the electrostatic force of the transfer charger 21 at the time of transfer, and thus needs to be separated from the transfer drum 7. Therefore, the separation charger device 8 cancels the electrostatic attraction force of the paper by corona discharge, and the separation claw 24 further separates the paper from the transfer drum 7 at its tip. The sheet separated from the transfer drum 7 is transported by the transport belt 25, the toner image is fixed by the fixing device 26, and the sheet is discharged from the copying machine main body.

[0004]

However, with the above configuration, when the paper is separated from the transfer drum 7,
For example, when the leading edge of the sheet is caught by the separation claw 24 and a jam or the like occurs, the sheet sunk into the inside of the separation charger device 8 (shown by the dotted line in FIG. 7). When the transfer drum 7 is pulled out from the main body of the copying machine in order to perform the jam processing in this state, the paper is caught on the shield of the separation charger device 8, the electrode wire, the front housing, etc., and the jam processing cannot be easily carried out. There is a problem that there is a risk of disconnection.

Further, when the paper bends and dives into the shield, the toner on the paper is scattered to generate toner dust, which may contaminate the surroundings.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a separation charger which can be easily jammed and does not cut the electrode wire.

[0007]

According to the present invention, there is provided a shield case main body having an opening on a surface facing a conveyed sheet and accommodating an electrode for separation, and a jammed sheet of the shield case main body. Is a separation charger including a front housing provided on the take-out side of the sheet and a protective member provided with a predetermined portion of the opening left open in order to prevent paper from slipping into the shield case body from the opening. .

[0008]

According to the present invention, even if the paper is jammed, the protective member provided in the opening prevents the paper from getting into the shield case body from the opening. Therefore, when the jammed paper is taken out, it does not get caught in the shield case.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 is a side view of a full-color copying machine having a separation charger according to an embodiment of the present invention.
That is, an original placing table 30 for placing an original and an original pressing cover 31 for pressing the placed original are provided above the main body of the copying machine, and an original reader 32 for reading the original by a CCD or the like is provided below the original placing table 30. A laser unit 33 that outputs a laser beam according to an electric signal of a document image read by the document reader 32 is provided.

Below the laser unit 33, the photosensitive drum 2 on which an electrostatic latent image is formed by the irradiation of the laser light.
0, a transfer drum 7 that contacts the photosensitive drum 20 and rotates the paper, a registration roller 22 that sends the paper to the transfer drum 7, a guide plate 23, and the like are provided. Inside the transfer drum 7, the toner image on the photosensitive drum 20 is provided. A transfer charger 21 for transferring the sheet to the sheet, a separation charger 8b for separating the sheet from the transfer drum 7, and the like, and a separation charger 8a is arranged outside the transfer drum 7 facing the separation charger 8b. There is. These separation chargers 8a and 8b constitute a separation charger device 8.

Further, a separation claw 24 for separating the paper is provided at a position close to the transfer drum 7 on the downstream side of the separation charger 8, and a conveyor belt 25 for conveying the paper is provided on the downstream side thereof, and further downstream thereof. A fixing device 26 that thermally fixes the toner is provided on the side. A paper discharge tray 38 for receiving the fixed and discharged paper is provided outside the main body of the copying machine near the fixing device 26, and a paper feed cassette 37 for storing the paper is provided under the fixing device 26. There is.
Further, on the side of the photosensitive drum 20, in order to develop the electrostatic latent image, the developing devices 34a, 34b, and
A developing device 34 including 34c and 34d is provided, and the developing device 34 is held by a moving frame body 35 to move the moving mechanism 3
6 is configured to be movable up and down.

FIG. 2 shows a part of the structure of the separation charger 8a provided in the main body of the copying machine constructed as described above. As shown in FIG. 2, the separation charger 8a includes a shield case main body 1 having a U-shaped cross section having an opening 5 on one surface, a front housing 3 provided at an end of the shield case main body 1 on the pull-out side, a front housing. 3 includes a handle 3a attached to the electrode 3, an electrode wire 2 for corona discharge stretched in the shield case body, and an insulating (for example, lumirror) protective member 4 bridged to the opening 5. A rear housing (not shown) is provided at the end opposite to the front housing 3.

The above-mentioned protective member 4 has a transparent, substantially L-shaped configuration, and a plurality (three in FIG. 2 shows an example in which three are attached, and three are similarly attached to the rear housing side as well. ) It is attached and has a claw 4b at the end of one leg, and the claw 4b is fitted in the slit 1b formed in the shield case body 1. Further, a projecting portion 4c is formed at the bent portion and is attached so as to be placed on the edge of the shield case body 1, and the end portions 4a of the other leg are provided on the inner wall of the shield case body 1 with the double-faced tape 1a.
It is affixed to and fixed on. In addition, the shape of the bridge portion (which is attached at a right angle to the direction of the electrode wire 2 rather than at a right angle) between both edges of the opening 5 is a hill shape in which a part is raised. Is higher than the upper surface 3b of the front housing 3 in order to prevent the paper from getting inside the shield case body 1 and to prevent the paper from being caught in the front housing 3 when the transfer drum 7 is pulled out by a jam process or the like. 2 (that is, in FIG. 2, the edge 5a of the opening 5 of the shield case body 1 and the upper surface 3b of the front housing 3 connected to the edge 5a are at the same height, so that the edge 5a of the opening 5 is closer to the sheet side than the edge 5a). The height of the edge of the protective member 4 is parallel to the edge of the shield case body 1 from the front housing 3 to the rear housing 9 as shown by a dotted line 10a in FIG. Is configured so that.).

Further, in this embodiment, the protective member 4 provided on the separation charger 8a (1) prevents contact with the toner image on the paper when the image forming process is performed on the paper (2). It is necessary to prevent dusting of the toner image on the paper due to bending of the paper when the paper causes separation failure.

That is, the distance between the protective member 4 and the transfer drum 7 is (1) at least a distance capable of preventing contact with the toner image on the paper, and (2) at the extent that dust does not occur on the toner image. It is set below the distance that can prevent bending.

Regarding the above (1) and (2), FIG. 5 and FIG.
It will be specifically described with reference to. 5 and 6, the thickness of the paper and the size of the toner layer are exaggerated for convenience of description. First, as shown in FIG. 5, the transfer drum 7
The maximum height of the toner image from is the maximum thickness of the applied paper (about 0.1 to 0.2 mm) and the maximum thickness of the toner layer (thickness of four types of toner during full color image formation, About 0.1 mm) and about 0.3 m
It is estimated to be m. That is, in order to satisfy the condition (1), the distance between the protective member 4 and the transfer drum 7 is 0.3 mm.
It should be larger than. As a result of confirming contact with the toner image, in the case of 1 mm or more,
The contact between the protective member 4 and the toner image did not occur.

As for the toner dust when the paper is bent (see FIG. 6), it was confirmed by experiments that when the distance between the protective member 4 and the transfer drum 7 was 5 mm, almost no toner dust was generated. In the case of 10 mm, toner dust was generated.

That is, in order to satisfy the condition (2), the distance between the protective member 4 and the transfer drum 7 should be 9 mm or less.

As a result, the distance A (see FIG. 5 or FIG. 6) between the protective member 4 and the transfer drum 7 is 1 mm or more and 9 m.
It may be set to m or less, and preferably 1 mm or more and 5
It is preferable to set it to mm or less. In this embodiment, it is set to 3 mm, which prevents contact with the toner image on the paper when performing image forming processing on the paper,
(2) The toner image on the paper is prevented from being dusted due to the bending of the paper when the paper has a poor separation.

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

First, the paper is sent to the transfer drum 7 by the registration roller 22 and the guide plate 23, and the leading end of the paper is fixed to a stay (not shown) and wound around the transfer drum 7. On the other hand, on the photosensitive drum 20, the electrostatic latent image is developed by the developing device 34 to form a toner image.
Next, when the transfer drum 7 rotates, the paper is transferred to the photosensitive drum 20.
Then, the transfer charger 21 transfers the toner image onto the sheet, the sheet is sent to the position of the separation charger device 8, where the sheet is electrically separated, and the separation claw 24 separates the transfer drum 7 from the transfer drum 7. Be separated. Normally, the sheet separated from the transfer drum 7 by the separation claw 24 is conveyed to the downstream side by the conveying belt 25, is thermally fixed by the fixing device 26, and is discharged to the sheet discharge tray 3.
The paper is discharged to 8.

When the sheet is fed to the separating claw 24, for example, when the sheet is caught by the separating claw 24, the sheet is further bent by the rotation of the transfer drum 7 and is bent, causing a wrinkle and a jam. Here, since the protective member 4 is provided in the opening 5 of the separation charger 8a outside the transfer drum 7 as described above, even if the paper is bent, it cannot enter the inside of the shield case body 1 as in the conventional case. Absent. Therefore, there is no risk of cutting the electrode wire 2. Furthermore, when the distance A between the protective member 4 and the transfer drum 7 is 3 mm, such a bending of the paper does not cause toner dust.

Next, when the transfer drum 7 is pulled out to remove the jammed paper, the surface of the paper moves along the edge of the protective member 4, so that the upper surface 3 of the front housing 3 is moved.
It can be easily pulled out without being caught in b, and jams can be removed.

In the above embodiment, the protective members 4 are attached one by one, but the present invention is not limited to this. For example, as shown in FIGS. 3 (a) and 3 (b), holes 6b are opened. The insulating plate member 6 may be attached by the claws 6a provided on the plate member 6. Alternatively, a mesh-shaped insulating member may be used. in short,
The separation charger 8a may be configured so as to prevent the intrusion of paper while leaving a part thereof open so that the separation effect by corona discharge can be secured.

Further, in the above embodiment, the height of the edge of the protective member 4 is set to be parallel to the edge of the shield case main body 1 as described above, but the invention is not limited to this. As shown in b), it may be configured such that it is inclined from the front housing 3 toward the rear housing 9 (so as to project toward the paper side) (dotted line 1).
0b). Alternatively, as shown in FIG. 4 (c), it may be inclined (dashed line 10c) so as to rise from the vicinity of the central portion toward the rear housing 9 (so as to project toward the sheet side). In short, when the transfer drum 7 is pulled out, the protective member 4 provided on the rear housing 9 side of the protective member 4 is protected against any protective member 4 so that the paper is not caught by the protective member 4 provided on the front housing 3 side. The member 4 may be configured so that it does not become lower.

Further, in the above embodiment, the height of the edge of the protective member 4 is higher than that of the surface of the front housing 3. However, the present invention is not limited to this, and the front housing 3 is actually used when the transfer drum 7 is pulled out. It is only necessary to prevent the sheet from being caught, and for example, the sheet may be configured to have substantially the same height as the surface of the front housing 3.

The protective member of the above embodiment may be made of any insulating material, and the material is not limited.

[0029]

As is apparent from the above description, the present invention provides a protective member which is provided with a predetermined portion of the opening left open in order to prevent the sheet from slipping into the shield case body from the opening. As a result, the jam processing can be easily performed, and there is an advantage that there is no fear of cutting the electrode wire.

Further, when the distance between the protective member and the transfer drum is set to a predetermined size, there is an advantage that the toner is not generated due to the bending of the paper and the surrounding area is not contaminated by the toner.

[Brief description of drawings]

FIG. 1 is a side view of a full-color copying machine including a separation charger according to an embodiment of the present invention.

FIG. 2 is a partial perspective view of the separation charger of the embodiment.

FIG. 3 (a) is a plan view of a separation charger according to another embodiment, and FIG. 3 (b) is a side view thereof.

4A, 4B, and 4C are schematic diagrams showing changes in height of the protective member from the front housing surface.

FIG. 5 is a schematic diagram illustrating a gap between a transfer drum and a protection member.

FIG. 6 is a schematic diagram illustrating a gap between a transfer drum and a protection member.

FIG. 7 is a partial side view of a copying machine including a conventional separation charger.

[Explanation of symbols]

 1 Shield Case Main Body 2 Electrode 3 Front Housing 4 Protective Member 5 Opening 6 Plate Member (Protective Member) 7 Transfer Drum 8 Separation Charger Device 8a, 8b Separation Charger 9 Rear Housing

Claims (3)

[Claims] 1. A shield case main body having an opening on a surface facing a conveyed paper and accommodating electrodes for separation, and a front provided on a side of the shield case main body where a jammed paper is taken out. A separation charger comprising: a housing; and a protection member provided with a predetermined portion of the opening left open in order to prevent the sheet from slipping into the shield case body from the opening. 2. The separation charger according to claim 1, wherein the protection member projects toward the sheet side from a surface of the front housing facing the sheet. 3. The separation charger according to claim 2, wherein the protection member has an area that projects more toward the rear housing from the front housing of the opening.