JPH05297688A - Electric discharge device - Google Patents

Abstract

PURPOSE:To surely clean a member to be cleaned over a long period by simple constitution. CONSTITUTION:A cleaning unit 3 which cleans the corona wire 4 of an electric discharge device provided in an electrophotographic copying system image forming device such as a copying machine or a printer is constituted of a holding member 7 and a pair of elastic cleaning members 8a and 8b whose base end parts are fitted to the holding parts 7a and 7b of the holding member 7 and whose free end parts are made to press-contact with each other. By inserting the wire 4 between the free end parts and moving the free end parts along the wire 4, the contact part of the free end parts of the members 8a and 8b becomes different on a going and a returning paths because the free end parts are reversed by sliding resistance with the wire 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine or a printer, which discharges the surface of a photosensitive drum by corona discharge.

[0002]

2. Description of the Related Art Generally, a discharge device of this type includes a corona wire which is a discharge electrode stretched in a shield case,
The grid is provided between the corona wire and the photosensitive drum. Nitrogen oxide (NOx) and floating toner tend to adhere to these corona wires, shield cases, and grids with the passage of time, and the discharge capacity tends to decrease.

As a result, for example, uneven charging occurs at the charging section and uneven transfer occurs at the transfer section, both of which cause uneven density in the copied image. In addition, in the separation section, a separation failure may occur and cause a jam.

In order to solve such inconvenience, conventionally, various cleaning devices have been proposed in which the cleaning member is slidably contacted with these members to be reciprocated to remove dirt on the members to be cleaned. Has been done.

For example, in Japanese Unexamined Patent Publication No. 51-133029, a holding member 7 of the same material as this shield member, as shown in FIG. 11, is slidably provided in a shield member on which a discharge electrode is stretched. A corona discharge device is shown in which a cleaning member 8 is removably attached to the holding member 7, and a corona wire 4 is slidably contacted with an insertion portion 8c of the cleaning member 8 to remove a deposit on the corona wire 4. There is.

Further, Japanese Utility Model Laid-Open No. 63-88860 discloses a pair of holding bodies which are arranged so as to be movable along a corona wire and whose one ends are engaged so as to be spaced apart from each other and approach each other. , A cleaning member that is disposed at one of the ends and that can hold the corona wire when the ends approach each other, and can slide along the corona wire in the shield case that stretches the corona wire. And an engaging member that is alternately engaged between both ends of the holding body so that the cleaning member slides in contact with the corona wire when moving in one direction and is separated when moving in the opposite direction. A cleaning tool for a corona charger with is shown.

[0007]

However, in the conventional discharge device as described above, in the former case, since the same surface of the cleaning member 8 is always in sliding contact with the corona wire 4 and reciprocates, FIG. As shown in (a), the cleaning member 8 moves upward in the drawing, and the adhered matter D removed in the forward path adheres to the corona wire 4 again in the backward path in which the cleaning member 8 moves downward as shown in (b). There is a defect. Further, since the part where the cleaning member 8 is slidably contacted with the corona wire 4 is always the same,
There is also a problem in that the load concentrates on that portion, wear is promoted, and the performance of the cleaning member deteriorates quickly.

In the latter case, in order to solve the above-mentioned point, the cleaning member which is slidably contacted with the corona wire on the outward path to be cleaned is released on the return path to prevent reattachment of the adhered matter. In the structure in which the cleaning member is brought into contact with and separated from the corona wire by the holding body, the operation is complicated, the reliability for reliable cleaning is low, and the number of parts is large, resulting in an increase in production cost.

The present invention has been made in view of the above points, and an object thereof is to make it possible to reliably clean a member to be cleaned for a long period of time with a simple structure.

[0010]

In order to achieve the above-mentioned object, the present invention provides an electrophotographic image forming apparatus having a cleaning device for holding a member to be cleaned by a pair of cleaning members and sliding it back and forth. In the discharge device of the apparatus, the cleaning member is reversed by the sliding resistance due to the sliding contact with the member to be cleaned so that the contact portion with the member to be cleaned is different between the forward path and the return path. is there.

In the above discharge device, it is preferable that the pair of cleaning members have elasticity and be inverted by elastic deformation thereof, and the pair of cleaning members serve as a pair of elastic holding members. They may be attached to each other and may be reversed by elastic deformation of the holding member. Further, the pair of cleaning members can be attached to the pair of rotatable holding members, respectively, and can be inverted by the rotation of the holding members.

In the above apparatus, the pair of rotatable holding members have an arcuate surface having the center of rotation as a center, and the pair of cleaning members are attached along the arcuate surfaces. More preferably, in the above-mentioned device, one of the rotation centers of the pair of holding members is displaced in the movement direction from a symmetrical position with respect to the member to be cleaned held by the pair of cleaning members, and It is also possible to allow the pair of cleaning members to overlap each other in a direction orthogonal to the moving direction thereof by a predetermined distance.

[0013]

With the discharge device according to the present invention configured as described above, when the cleaning member reciprocates, it is reversed by the sliding resistance caused by the sliding contact with the member to be cleaned, and the contact position between the cleaning member and the member to be cleaned is reversed. Is different on the outbound route and the inbound route. This eliminates the risk of reattaching the adhered matter removed on the outward path on the return path, and the sliding contact portion of the cleaning member with the member to be cleaned is dispersed at two locations, thereby doubling the life of the cleaning member.

In the above apparatus, if the cleaning member is made to have elasticity, the structure is simplified by changing only the cleaning member in the same device as the conventional one, and the holding member to which the cleaning member is attached is elastically deformed. If you do
The elastic force of the holding member can be set arbitrarily, and the contact pressure of the cleaning member can be strengthened for more reliable cleaning.

Further, if the holding member to which the cleaning member is attached can be rotated, an appropriate contact pressure can be maintained for a long period of time, and in this device, the holding member is centered on the rotation center. In the case of having the arc surface, the contact pressure of the cleaning member with respect to the member to be cleaned does not change, so that the cleaning member can be reversed more smoothly.

Further, in the above apparatus, the pair of holding members are displaced from the symmetrical position in the moving direction, and the pair of cleaning members are arranged so as to overlap with the member to be cleaned. Can be brought into stronger contact with the member to be cleaned, and a more reliable cleaning effect can be achieved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. Prior to that, a discharge device for carrying out the present invention will be briefly described with reference to FIG.

In this discharge device, a corona wire 4, which is a discharge electrode, is stretched between a pair of end blocks 1a and 1b made of a heat-resistant resin material, the periphery of which is surrounded by a shield member 5, and a shield member 5 is provided. A grid 2 is arranged in the opening on the side of the body to be charged (not shown).

The cleaning unit 3 moves to the left and right in the drawing while slidingly contacting the corona wire 4 by manual or automatic moving means such as a motor (not shown). At that time, the cleaning member provided in the cleaning unit 3 causes the corona wire 4 to move. The members to be cleaned are cleaned by slidingly contacting the inner surface of the shield member 5 and the upper surface of the grid 2.

FIG. 1 is a perspective view showing a first embodiment of the present invention, in which the cleaning section 3 has U-shaped holding sections 7a and 7b which move along the corona wire 4 and is flame-retardant. The cleaning member 8a is composed of a holding member 7 made of a resin material, and a pair of elastic cleaning members 8a, 8b, such as foamed polyurethane, having proximal ends attached to the inner surfaces of the holding portions 7a, 7b, respectively. , 8b are brought into pressure contact with each other with a predetermined contact pressure, and the corona wire 4 is inserted therebetween.

When the holding member 7 is reciprocated along the corona wire 4 with such a structure, the cleaning members 8a and 8b move upward in the drawing as shown in FIG. The sliding resistance of the cleaning members 8a, 4b causes the moving speed of each free end to lag behind that of the base end.
8b is elastically deformed, and the upper edge side of each free end is brought into sliding contact with the corona wire 4 to clean the attached matter.

Conversely, as shown in FIG. 2B, the cleaning member 8
In the return path in which a and 8b move downward in the figure, the lower edge side of each free end slides on the corona wire 4 for the same reason. In this way, the direction of elastic deformation of the cleaning member changes between the forward path and the return path of the cleaning process, and the advancing side edges of the cleaning members 8a and 8b always come into sliding contact with the corona wire 4, and the adhered matter on the return path reappears. The adhesion is prevented and the cleaning members 8a, 8
The life of b can be doubled as compared with the conventional one shown in FIG.

FIG. 3 is a perspective view showing a second embodiment of the present invention. The holding member 7 is made of a resin material having elasticity and the holding arms 7a ', 7'are attached to the holding portions 7a, 7b.
b '(see FIG. 4) is integrally provided to project the holding arms 7a', 7 '
The base ends of the cleaning members 8a and 8b are attached to b '. As can be seen from FIG. 4, in the forward path shown in (a) and the return path shown in (b) of FIG. 4, the holding arms 7a ′, 7b ′ are moved by the sliding resistance between the cleaning members 8a, 8b and the corona wire 4. Elastically deforming in different directions, the contact surfaces of the cleaning members 8a and 8b with the corona wire 4 are different, as in the first embodiment.

According to the second embodiment, in addition to the effect of the first embodiment described above, by appropriately selecting the material, shape and the like of the holding member, the pressure contact force of the cleaning members 8a and 8b against the corona wire is increased. The cleaning effect can be enhanced by increasing the strength of the cleaning member and the elastic force of the cleaning members 8a and 8b is not restricted. Therefore, it is possible to select a cleaning member having a large cleaning force.

Next, FIG. 5 is a perspective view showing a third embodiment of the present invention, in which the second holding members 7c and 7d are rotatably mounted by the shafts 9a and 9b of the first holding member 7. Then, the cleaning members 8a, 8 are provided on the surfaces of the second holding members 7c, 7d which face each other.
Stick b and press them together.

In the third embodiment, for the same reason as in the previous embodiments, the second holding members 7c and 7d are centered on the shafts 9a and 9b as shown in FIGS. 6 (a) and 6 (b). By rotating each, the contact portions of the cleaning members 8a and 8b with respect to the corona wire 4 can be made different between the forward movement and the backward movement.
In this embodiment, since it does not depend on the elastic deformation of the cleaning member and the holding member, it is possible to maintain an appropriate pressure contact force for a long period of time.

FIG. 7 is a perspective view showing a fourth embodiment of the present invention in which a part of the above-mentioned third embodiment is modified.
The attaching surfaces of the cleaning members 8a and 8b of the holding members 7c and 7d are circular arc surfaces centering on the shafts 9a and 9b, and the second holding members 7c and 7d are stoppers provided on the first holding member 7. Each rotation range is regulated by (not shown) so that the contact between the cleaning members 8a and 8b and the corona wire 4 can be maintained, but the other configurations are the same as in the third embodiment.

According to the fourth embodiment, as shown in FIG.
As shown in (b), there is no change in the pressure contact force of the cleaning members 8a and 8b with respect to the corona wire 4 due to the rotation of the second holding members 7c and 7d, and the cleaning members 8a and 8b can be respectively moved in the forward path and the multipath. The sliding contact portion can be switched smoothly.

FIG. 9 shows a fifth embodiment of the present invention in which a part of the above-mentioned fourth embodiment is further modified.
Instead of arranging the positions of the shafts 9a, 9b of the holding members 7c, 7d in the above-mentioned manner symmetrically with respect to the corona wire 4 as in the embodiments described above, one of them is displaced in the moving direction of the first holding member 7. And the asymmetry between the shafts 9a and 9b is made slightly smaller than that of the fourth embodiment.

According to the fifth embodiment, each cleaning member 8
The sliding contact surfaces of a and 8b with the corona wire 4 are the cleaning members 8
Since the distances x overlap in the direction orthogonal to the moving directions of a and 8b, the pressure contact force between the cleaning members 8a and 8b and the corona wire 4 can be made stronger, and at the same time,
The sliding surface can be made larger.

In the above embodiment, the pressure contact force of the cleaning member with respect to the corona wire is replaced by the elastic force of the cleaning member itself or the holding member, and a spring such as SUS which is resistant to repeated deformation and ozone generated from the discharge device. If this is generated, the pressure contact force can be maintained for a longer period of time, and the corona wire can be cleaned more reliably.

In each of the above embodiments, the case where the corona wire is cleaned has been described, but the members to be cleaned such as the grid and the shield member can be similarly cleaned.

[0033]

As described above, in the discharge device of the image forming apparatus according to the present invention, the contact portion of the cleaning member is different between the forward path and the return path due to the sliding resistance with the member to be cleaned. Therefore, there is no risk of reattaching the deposits removed on the outward path on the return path, and the contact portion of the cleaning member with the member to be cleaned is dispersed at two locations, so that the wear is not concentrated at one location and the life is doubled. be able to.

Further, in the above apparatus, if the cleaning member has elasticity, the cleaning unit may have the same structure as the conventional one, and the structure is simple and the increase of the production cost can be suppressed, and the cleaning member is held. When the holding member has elasticity, its elastic force can be freely set regardless of the cleaning member, so that the contact pressure of the cleaning member can be strengthened and more reliable cleaning can be performed.

Further, when the holding member to which the cleaning member is attached can be rotated, since the elasticity of the cleaning member and the holding member is not relied upon, an appropriate pressure contact force can be maintained for a long time, In this device, if the holding member has an arcuate surface with the center of rotation as the center, even if the holding member rotates, the pressure contact force of the cleaning member to the member to be cleaned can be kept constant, and the cleaning member Can be reversed more smoothly.

Further, in the above-mentioned device, the pair of holding members which are displaced from the symmetrical position so as to overlap in the direction orthogonal to the moving direction of the holding member has a stronger contact pressure between the cleaning member and the member to be cleaned. At the same time, it is possible to increase the number of contact areas and to further enhance the reliable cleaning effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the same operation.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of the same operation.

FIG. 5 is a perspective view showing a third embodiment of the present invention.

FIG. 6 is an explanatory view of the same operation.

FIG. 7 is a perspective view showing a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram of the same operation.

FIG. 9 is an operation explanatory view of the fifth embodiment of the present invention.

FIG. 10 is a configuration diagram showing a discharge device including a cleaning device embodying the present invention.

FIG. 11 is a perspective view showing an example of a cleaning device for a discharge device used in a conventional copying apparatus.

FIG. 12 is an explanatory view of the same operation.

[Explanation of symbols]

1a, 1b End block 2 Grid 3 Cleaning unit 4 Corona wire (member to be cleaned) 5 Shield member 7 Holding members 8a, 8b Cleaning members 9a, 9b Shaft (rotation center of the holding member)

Claims (6)

[Claims] 1. A discharge device of an electrophotographic image forming apparatus, comprising a cleaning device that holds a member to be cleaned by a pair of cleaning members and slides it back and forth, wherein the cleaning member is the member to be cleaned. The discharge device is characterized in that the contact portion with the member to be cleaned is made different between the forward path and the return path by reversing due to the sliding resistance due to the sliding contact with. 2. The discharge device according to claim 1, wherein the pair of cleaning members have elasticity and are inverted by the elastic deformation. 3. The discharge device according to claim 1, wherein the pair of cleaning members are attached to the pair of elastic holding members, respectively, and are inverted by elastic deformation of the holding members. 4. The discharge device according to claim 1, wherein the pair of cleaning members are attached to the pair of rotatable holding members, respectively, and are inverted by the rotation of the holding members. 5. A pair of rotatable holding members have arcuate surfaces centered on the center of rotation, and the pair of cleaning members are attached along the arcuate surfaces. The discharge device described. 6. One of the rotation centers of the pair of holding members is displaced in the movement direction from a symmetrical position with respect to the member to be cleaned held by the pair of cleaning members, and the pair of cleaning members are moved. The discharge device according to claim 5, wherein a predetermined distance overlaps in a direction orthogonal to the direction.