JP2002289323A - Corona discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corona discharge device wherein not only adhered materials such as silicon or the like but also those of soft substances can be removed easily from a plate-formed electrode and wherein breakage of a tip part of the plate-formed electrode can be prevented. SOLUTION: This device is equipped with the plate-formed electrode 31 formed in a serration state, cleaning parts 34, 34 of the plate-formed electrode having a contact face of a convex curved face state to contact with both side faces of the plate-formed electrode 31, and a transportation means to move the cleaning parts 34, 34 of the plate-formed electrode along a longitudinal direction of the plate-formed electrode 31. As the contact face of the cleaning parts 34, 34 of the plate-formed electrode successively and gradually contacts along the convex curved face shape toward an acute angle point of the tip of the plate-formed electrode 31, a sudden force will not work on the acute angle point of the tip of the plate-formed electrode 31, thereby the adhered materials adhered to the plate-formed electrode 31 are removed by the frictional force between the cleaning parts 34, 34 of the plate-formed electrode and the plate-formed electrode 31 without damaging the acute angle point of the tip of the plate-formed electrode 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona discharge device used for an image forming apparatus such as an electrophotographic copying machine, a printer and a facsimile.

[0002]

2. Description of the Related Art Conventionally, as a corona discharge device, a device having a plate-like electrode having a sawtooth-shaped needle electrode portion, which is used for a charging device of an electrophotographic device and is disclosed in Japanese Patent Application Laid-Open No. H07-163,959 is known. No. -28300.
This corona discharge device uses a plate-like electrode in which a plurality of sharp discharge ends are arranged in a line and the pitch of the sharp discharge ends is set at a certain interval, and has advantages such as low ozone and high efficiency. I have. Such a corona discharge device is currently employed in a charging device of many image forming apparatuses.

However, the corona discharge device using the plate-shaped electrode having the saw-toothed needle electrode portion has the following problems due to its characteristics.

The "needle electrode portions" are, as the name implies, arranged in a needle shape on the side facing the image carrier and in a line at a predetermined interval. By applying a high voltage or the like to the plate-like electrode, the discharge is intensively performed in the image carrier direction from the tip of the needle electrode portion. This discharge generates a large amount of deposits at the tip of the needle electrode. For example, silicon (Si) adheres and grows at the tip of the needle electrode around the discharge point, and the growth of silicon causes discharge unevenness. Occurs. In addition, when used for a long time, substances such as minute toner, post-processing agent, and paper powder floating in the apparatus adhere to the tip of the needle electrode portion, and similarly, uneven discharge occurs.

When a corona discharge device in which such discharge unevenness occurs is used as a charging device, unevenness occurs in the potential of the surface of the image bearing member. Become. When a corona discharge device in which discharge unevenness occurs is used as a transfer device, unevenness occurs in an electric field for moving untransferred toner on the image carrier to a recording material, so that an image after image formation has a different density. A portion is generated and becomes image noise. As described above, it is difficult for the corona discharge device to maintain its original function due to various substances adhering to the tip portion of the sawtooth-shaped needle electrode portion.

By the way, the above-mentioned deposits can be removed by rubbing lightly, especially in the case of silicon. Therefore, several methods have already been disclosed as a method for removing the deposit such as silicon from the saw-toothed needle electrode portion of the plate-like electrode. As shown in Japanese Patent Application Laid-Open No. 7-43990, in a corona discharge device provided with a plate-like electrode, the plate-like electrode is sandwiched from both sides by two rollers, and both rollers are rotated, whereby the plate-like electrode is rotated. There is an electrode cleaning device that scrapes off and removes deposits attached to the needle electrode unit. According to this electrode cleaning device, 2
With two rollers sandwiching the plate electrode from both sides,
The roller rotates by reciprocating in the longitudinal direction of the plate electrode. By doing so, silicon or the like adhering to the tip of the needle electrode portion of the plate-shaped electrode is destroyed / crushed and removed by the pressure for sandwiching the plate-shaped electrode from both sides and the rotating force of the roller.

On the other hand, another corona discharge device is disclosed in
As shown in Japanese Patent Application Laid-Open No. 000-242102, a plate-shaped electrode cleaning unit made of flocked or felt for cleaning the wire is provided, and the wire is moved by rotating the bobbin, thereby attaching the wire. There is an electrode cleaning device for removing the kimono. JP-A-2000-242102
According to the publication, it is possible to effectively remove the deposits by the frictional force generated by the pressing force between the plate-shaped electrode cleaning unit and the wire.

The corona discharge device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-43990 is effective for substances such as silicon which can be broken and removed only by applying a certain amount of force, such as silicon. However, for relatively soft and viscous deposits such as toner slightly floating around the plate-like electrode and paper powder detached from the recording material, the plate-like electrode is sandwiched from both sides by two rollers. By rotating both rollers, the above-mentioned soft deposits are further pressed against the plate-like electrode, eventually increasing the adhesion strength from the initial state, and instead of removing the deposits, the plate-like electrodes are contaminated. The result is that it encourages.

On the other hand, in the corona discharge device described in JP-A-2000-242102, it is needless to say that this form can be applied to a plate-like electrode. In that case, since the plate-shaped electrode cleaning part is formed by flocking or felt,
In particular, at the end of the surface in contact with the plate electrode, the fiber portion of the flocked or felt is caught at the acute point of the tip of the needle electrode portion of the plate electrode, and only the movement force of the plate electrode cleaning unit increases. In the worst case, the sharp point at the tip of the needle electrode portion of the plate electrode may be bent. As a result, the discharge direction and the discharge point from the tip of the needle electrode portion of the plate-like electrode change, and the above-described discharge unevenness occurs and appears as image noise.

As described above, the corona discharge device disclosed in Japanese Patent Application Laid-Open No. 7-43990 has a problem that it is difficult to remove deposits of soft substances such as toner and paper dust.
In the corona discharge device disclosed in Japanese Patent Application Laid-Open No. 0-242102, there is a problem that a tip portion of the plate-shaped electrode is damaged.

SUMMARY OF THE INVENTION An object of the present invention is to provide a corona discharge device capable of easily removing not only deposits such as silicon but also deposits of a soft substance from a plate electrode and preventing breakage of a tip portion of the plate electrode. To provide.

[0012]

According to a first aspect of the present invention, there is provided a corona discharge device comprising: a plate-like electrode formed in a saw-tooth shape; and a convex curved surface contacting at least one side surface of the plate-like electrode. A plate-shaped electrode cleaning unit having a contact surface having a shape,
Moving means for moving the plate-shaped electrode cleaning section along the longitudinal direction of the plate-shaped electrode.

According to the corona discharge device of the first aspect,
When the plate-shaped electrode cleaning unit is moved along the longitudinal direction of the plate-shaped electrode by the moving unit, the plate-shaped electrode cleaning unit comes into contact with an acute point at the tip of the saw-shaped plate-shaped electrode. The surface continuously and gradually contacts along the convex curved surface shape. Therefore, since no sharp force is applied to the acute point at the tip of the plate-like electrode, without damaging the acute point at the tip of the plate-like electrode, any attached matter adhering to the plate-like electrode is removed. It can be removed by frictional force with the plate-shaped electrode cleaning unit.

According to a second aspect of the present invention, in the corona discharge device according to the first aspect, the moving means moves the plate-shaped electrode cleaning section to clean the plate-shaped electrode. It is characterized in that the plate-shaped electrode cleaning section is moved only in one of the directions along the longitudinal direction of the electrode.

According to the corona discharge device of the second aspect,
When the plate-shaped electrode cleaning unit is moved to clean the plate-shaped electrode, the moving unit moves the plate-shaped electrode cleaning unit in only one of the directions along the longitudinal direction of the plate-shaped electrode, and moves in the moving direction. By inclining the tip shape of the plate-shaped electrode in the opposite direction, the stress applied to the tip portion of the plate-shaped electrode is dispersed in the direction in which the tip of the needle electrode portion of the plate-shaped electrode is inclined. The tip can be prevented from being damaged.

According to a third aspect of the present invention, there is provided a corona discharge device, comprising: a plate-like electrode formed in a saw-tooth shape; a plate-like electrode cleaning unit having a contact surface in contact with at least one side surface of the plate-like electrode; Moving means for moving the plate-shaped electrode cleaning section along the longitudinal direction of the plate-shaped electrode, wherein the moving means moves the plate-shaped electrode cleaning section to clean the plate-shaped electrode. It is characterized in that the plate-shaped electrode cleaning section is moved only in one of the directions along the longitudinal direction of the electrode.

According to the corona discharge device of the third aspect,
When the plate-shaped electrode cleaning unit is moved to clean the plate-shaped electrode, the moving unit moves the plate-shaped electrode cleaning unit in only one of the directions along the longitudinal direction of the plate-shaped electrode. By inclining the tip shape of the plate-shaped electrode toward, damage to the tip portion of the plate-shaped electrode can be prevented.

According to a fourth aspect of the present invention, in the corona discharge device according to the third aspect, the contact surface of the plate-shaped electrode cleaning portion that contacts the side surface of the plate-shaped electrode has a convex curved shape. And

According to the corona discharge device of the fourth aspect,
The contact surface of the plate-shaped electrode cleaning unit is gradually and continuously in contact with the acute point at the tip of the saw-shaped plate-shaped electrode along a convex curved surface shape. No sharp force is applied to the acute point at the tip of the electrode. Therefore, without damaging the acute point at the tip of the plate-like electrode,
Any adhering matter adhering to the plate electrode can be removed by a frictional force with the plate electrode cleaning unit.

According to a fifth aspect of the present invention, there is provided a corona discharge device according to any one of the first to fourth aspects.
The plate-shaped electrode cleaning unit is a pair of plate-shaped electrode cleaning units that are in contact with both side surfaces of the plate-shaped electrode.

According to the corona discharge device of the fifth aspect,
By a pair of plate electrode cleaning units, each of which comes into contact with both side surfaces of the plate electrode, it is possible to effectively remove discharge products and toner and other deposits from both sides of the plate electrode.

The corona discharge device according to claim 6 is the corona discharge device according to any one of claims 2 to 5,
The plate-shaped electrode has a long plate-shaped base, and a needle electrode portion formed in a sawtooth shape on one long side of the base, and the tip of the needle electrode portion of the plate-shaped electrode is the plate-shaped electrode. The plate-shaped electrode is inclined in a moving direction when the plate-shaped electrode is cleaned by the plate-shaped electrode cleaning section.

According to the corona discharge device of the sixth aspect,
When the plate-shaped electrode cleaning unit is moved to clean the plate-shaped electrode, stress applied to the tip of the plate-shaped electrode is dispersed in a direction in which the tip of the needle electrode unit of the plate-shaped electrode is inclined. In addition, damage to the tip of the plate-like electrode can be prevented.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a corona discharge device according to the present invention will be described in detail with reference to the illustrated embodiments.

(First Embodiment) FIG. 1 is a sectional view showing a schematic configuration of an image forming apparatus using a corona discharge device according to a first embodiment of the present invention as a charging device and a transfer device. (Not shown), a cylindrical latent image carrier 3 rotated by a charging device using a corona discharge device for forming an electric charge on the latent image carrier 1, and a latent image carrier 1 based on image information An exposure device for forming an electrostatic latent image thereon; a developing device 5 for forming a toner image on the latent image carrier 1 to make the electrostatic latent image a visible image; 1 is a transfer device using a corona discharge device for transferring the toner image on the transfer medium (not shown), and 7 is a residual toner image that cannot be completely transferred to the transfer medium by the transfer device 6. Cleaning means for removing the toner from the latent image carrier 1, and 8 for erasing the electrostatic latent image on the latent image carrier 1 Because of discharging means, 20 denotes a fixing device 20. The latent image carrier 1, the charging device 3, the exposure device 4, the developing device 5, the transfer device 6, the cleaning means 7, and the charge eliminating device 8 constitute a latent image carrier unit. The toner image formed on the transfer medium by the latent image carrier unit is permanently fixed on the transfer medium by the fixing device 20.

FIG. 2 is a perspective view schematically showing the charging device 3. Here, the charging device 3 will be described, but the basic configuration of the transfer device 6 is naturally the same. As shown in FIG. 2, the charging device 3 is a scorotron charging device using a saw-toothed plate-like electrode 31. The charging device 3 has a basic configuration in which an electrode cleaning device 30, a discharge stabilizing plate 32, and a control electrode 33 are arranged around a plate electrode 31.

The charging device 3 includes a plate electrode 31, a discharge stabilizing plate 32, and a control electrode 3 at a predetermined timing.
A predetermined charge is formed on the latent image carrier 1 by applying a voltage to the latent image carrier 3. At this time, it is possible not only to apply a voltage to the discharge stabilizing plate 32 but also to ground the discharge stabilizing plate 32, and not only to apply a voltage to the control electrode 33, but also through a varistor or a Zener diode. It is also possible to obtain a predetermined voltage.

The electrode cleaning device 30 includes a plate-shaped electrode cleaning section 34 disposed so as to sandwich the plate-shaped electrode 31,
34, and a holding portion 38 for holding the plate-shaped electrode cleaning portions 34, 34. The plate-shaped electrode cleaning units 34, 34
Can be reciprocated in the longitudinal direction of the plate electrode 31 (that is, in the longitudinal direction of the image carrier surface) by the moving means 35. When the plate-shaped electrode cleaning units 34 and 34 move, for example, a guide unit (not shown) or a rail (not shown) provided on the discharge stabilizing plate 32, the control electrode 33, the image forming apparatus itself, or the like. ), Etc., the plate-shaped electrode 31 does not deviate from the predetermined trajectory when reciprocating, and the plate-shaped electrode cleaning units 34, 34 themselves do not naturally rotate. Further, the power for moving the plate-shaped electrode cleaning units 34, 34 can be generated by electric power from a motor or the like, and can also be manually operated by the operator.

FIG. 3 is a detailed perspective view of a main part of the charging device 3 including the plate-shaped electrode cleaning portions 34, 34. In addition,
In the first embodiment, a description will be given of a configuration in which a pair of plate-shaped electrode cleaning units 34 and 34 are disposed so as to sandwich the plate-shaped electrode 31. A configuration in which only one of the side surfaces is in contact is also possible.

As shown in FIG. 3, the plate-shaped electrode cleaning portions 34 are arranged so as to sandwich the plate-shaped electrode 31 from both sides. The plate-shaped electrode cleaning units 34 and 34 are held by a holding unit 38 having a U-shaped cross section, and are in contact with the plate-shaped electrode 31 from both sides so as to apply an appropriate pressure.

A moving means 35 is attached to the holding section 38 on the side opposite to the discharging direction of the charging device 3. In this moving means 35, a ball bearing (not shown) is embedded in a ball bearing portion 39 fixed to the holding portion 38, and a ball screw 40 is provided through the ball bearing portion 39. The rotation of the ball screw 40 causes the holding portion 38 together with the ball bearing portion 39 to move the plate electrode 31.
Can be moved along the longitudinal direction of. Although not shown, a bar-shaped member is directly attached to the holding portion 38 in place of the ball bearing and the ball screw, and the rod-shaped member is pushed and pulled, so that the plate-shaped electrode cleaning portions 34, 34 are formed.
May be moved. Further, the plate-shaped electrode cleaning units 34, 3
4 and the holding unit 38 are retracted to the non-image forming area during a normal image forming operation, and can be moved only when cleaning the plate-shaped electrode 31 (during the non-image forming operation).

FIG. 4 is a view of the plate-like electrode 31 and the plate-like electrode cleaning portions 34, 34 viewed from the needle electrode portion 31b.
4, reference numeral 31c denotes a discharge point at the tip of the needle electrode portion 31b of the plate electrode 31. The cross-sectional shape of the plate-shaped electrode cleaning portions 34, 34 is a convex curved surface shape. The above plate-shaped electrode cleaning unit 3
The convex curved surfaces of 4, 34 have a convex curved surface on both sides with a straight line passing through the center point of the length in the longitudinal direction of the plate-like electrode 31 and being perpendicular to the longitudinal direction as a symmetric axis. Here, the term “convex curved surface shape” means a shape with gentle corners.

The plate-shaped electrode cleaning portions 34, 34 are arranged so as to be in contact with both side surfaces of the plate-shaped electrode 31, and may be made of, for example, a felt material, a moquette material, a flocked material, a urethane material, a resin material, or the like. Become. Although not shown, the plate-shaped electrode cleaning units 34 and 34 may have a two-layer structure made of different materials. In the case of this two-layer structure, the material of the layer in contact with the plate-shaped electrode 31 is appropriately selected. In addition, the contact force can be more dispersed and uniformized.

FIG. 5 is a side view of the state in which the plate-shaped electrode cleaning unit 34 is in contact with one side surface of the plate-shaped electrode 31. As shown in FIG. Is a substantially square shape having a contact surface with a certain area or more that covers at least the tip portion of the needle electrode portion 31b of the plate-like electrode 31.

If the plate electrode 31 is contaminated, the holding section 38 is moved by the moving means 35 shown in FIG. The plate-shaped electrode cleaning unit 34 moves while being in contact with.

At this time, by making the contact surface of the plate-shaped electrode cleaning portion 34 that comes into contact with both side surfaces of the plate-shaped electrode 31 into a convex curved shape, the needle electrode portion 31b formed in a sawtooth shape of the plate-shaped electrode 31 is formed. The plate-shaped electrode cleaning unit 34 is gradually and continuously in contact with the acute point of the tip along the convex curved surface shape, and the sharp-point at the tip of the needle electrode portion 31b of the plate-shaped electrode 31 is unnecessary. No more sudden force is applied.

As described above, the tip of the needle electrode portion 31b of the plate electrode 31 is not damaged, and the plate electrode cleaning portion 34 moves relative to the plate electrode 31, thereby forming the convex curved surface. Particularly, a strong frictional force is generated in the vicinity of the vertex, whereby it is possible to remove the deposit attached to the plate electrode 31.

Further, by a pair of plate-shaped electrode cleaning portions 34, 34 in which the respective contact surfaces come into contact with both side surfaces of the plate-shaped electrode 31, dusts such as discharge products and toner from both sides of the plate-shaped electrode 31 are removed. It can be effectively removed.

(Second Embodiment) FIG. 6 is a perspective view schematically showing a corona discharge device according to a second embodiment of the present invention. As shown in FIG. 6, this corona discharge device is a scorotron charging device using a saw-tooth plate-like electrode 151, and is used for a charging device and a transfer device of an image forming apparatus having the same configuration as the image forming apparatus of the first embodiment. Can be

As shown in FIG. 6, the above-described corona discharge device has a basic configuration in which a plate-like electrode 151 is centered, and an electrode cleaning device 130, a discharge stabilizing plate 132, and a control electrode 133 are arranged around the plate-like electrode 151. The electrode cleaning device 130 includes a plate-shaped electrode cleaning unit 13 disposed to sandwich the plate-shaped electrode 151.
4, 134, and a holding portion 138 for holding the plate-shaped electrode cleaning portions 134, 134. The plate-shaped electrode cleaning portions 134 and 134 are in contact with the plate-shaped electrode 151 from both sides so as to apply an appropriate pressure. The holding unit 13
8 for guiding plate 8 in the longitudinal direction of plate electrode 151
1 is arranged.

The tip of the needle electrode portion 151b facing the image carrier (not shown) is connected to the plate electrode 151.
The shape has an inclination only in one longitudinal direction.
In FIG. 6, one direction on the back side of the image forming apparatus shown in FIG.
In this case, the inclination is shown only in the direction perpendicular to the plane of FIG. 1 and downward, but it is naturally possible to have the inclination only in one direction on the near side (in the direction perpendicular to the plane of FIG. 1 and upward).

The needle electrode portion 151b of the plate electrode 151
Is not limited to a triangular shape having sides substantially perpendicular to the longitudinal direction of the plate electrode 151 as shown in FIG.
It goes without saying that a saw-tooth shape that is inclined only in one direction may be used.

The corona discharge device forms a predetermined charge on the latent image carrier 1 by applying a voltage to the plate electrode 151, the discharge stabilizing plate 132, and the control electrode 133 at a predetermined timing. At this time, not only is the voltage applied to the discharge stabilizer 132 but also
Can be grounded, and it is possible not only to apply a voltage to the control electrode 133 but also to obtain a predetermined voltage via a varistor, a Zener diode, or the like.

The plate-shaped electrode cleaning units 134, 134 arranged so as to sandwich the plate-shaped electrode 151
Only when the plate-shaped electrode 151 is in contact with the plate-shaped electrode 151, the plate-shaped electrode 151 can be moved in one direction only (ie, in the longitudinal direction of the surface of the image carrier). In this case, the moving direction is the same direction as the direction in which the needle electrode portion 151b of the plate electrode 151 is inclined, that is, the back side direction of the image forming apparatus shown in FIG. 1 (the direction perpendicular to the paper surface of FIG. 1 and downward). It is.

The plate-shaped electrode cleaning units 134, 134
When the plate moves to clean the plate electrode 151, the plate electrode cleaning units 134, 134
(Not shown) or the like so as not to deviate from a predetermined trajectory. Of course, the plate-shaped electrode cleaning units 134 and 134 themselves do not rotate. Further, the plate-shaped electrode cleaning section 134,
The motive power for moving 134 can be provided by electric power from a motor or the like, and can also be provided by the operator himself, that is, manually.

FIG. 7 is a perspective view of a main part including the plate-shaped electrode cleaning portions 134 of the corona discharge device. In this corona discharge device, a moving unit (not shown) is attached to the holding unit 138. For example, the moving unit is configured such that the wire is embedded in the holding unit 138, and the holding unit 138 can move in the longitudinal direction of the plate electrode 151 by moving the wire in the longitudinal direction of the plate electrode 134. ing. Of course, it is needless to say that the movement can be performed by other methods without using a wire.

Further, as shown in FIG.
8 is a first block 101 and a second block 1 that can be divided.
The plate-shaped electrode cleaning portions 134 are urged by springs (not shown) from both sides so as to sandwich the plate-shaped electrode 151 from both sides. The first block 10
The protrusions 10 are provided on the sides of the first and second blocks 102 facing each other.
1a and 102a are provided respectively, and the convex portions 101a and 10a thereof are provided.
Notches 111 and 112 are provided at opposing ends of the side surfaces of the first and second blocks 101 and 102 having 2a, and the notches 111 and 112 form a V-groove.

In the second embodiment, the plate electrode 1
51, a pair of plate-shaped electrode cleaning units 134, 1
34 is described, the 1
It is also possible to adopt a configuration in which two plate-shaped electrode cleaning portions are in contact with only one side surface of the plate-shaped electrode.

The plate-shaped electrode cleaning units 134, 134
During the normal image forming operation, the home position (state A shown in FIG. 10) is a non-image forming area.
, And can be moved only when cleaning the plate-shaped electrode 151 (during a non-image forming operation).

FIG. 8 is a view of the plate-like electrode 151 and the plate-like electrode cleaning parts 134, 134 viewed from the needle electrode part 151b side. As shown in FIG. 8, the plate-shaped electrode cleaning units 134, 134
Is configured to be in contact with the plate-like electrode 151, and is made of, for example, a felt material, a moquette material, a flocked material, a urethane material, a resin material, or the like. Further, as shown in FIG. 8, the cross-sectional shape of the plate-shaped electrode cleaning units 134, 134 is also substantially square. Of course, it is also possible to use a plate-shaped electrode cleaning portion 34, 34 shown in the first embodiment, which has a contact surface having a convex curved shape.

Although not shown, the plate-shaped electrode cleaning unit 13 is not shown.
4,134 may be a two-layer structure made of different materials. In the case of this two-layer structure, the contact force can be dispersed and uniformized by appropriately selecting the material in contact with the plate-shaped electrode 151 and another layer. It becomes more possible.

FIG. 9 shows the plate-shaped electrode cleaning section 134,
FIG. 10 is a side view showing a state in which 134 is in contact with a side surface of the plate electrode 151. As shown in FIG. 9, the plate electrode cleaning units 134 and 134 cover at least the distal end portion of the plate electrode 151. It has a substantially quadrangular shape having a contact surface with an area with a certain margin.

FIG. 10 shows the plate-shaped electrode cleaning units 134 and 13.
FIG. 9 is a schematic perspective view illustrating the operation of a guide section 141 during the operation of FIG. When the plate electrode 151 is contaminated, first, as shown in FIG.
The holding section 138 is moved by the moving means from the home position (state A) at one end to the other end. In conjunction with the movement of the holding portion 138, the wedge shape formed by the bent portion 142 a of the first guide plate 142 and the bent portion 143 a of the second guide plate 143 of the guide portion 141 is changed to the holding portion 13.
8 (notches 111, 112 shown in FIG. 7). Thereby, the holding portion 138 is divided into the first block 101 and the second block 102, and the holding portion 138 is guided by the guide portion 141 in a state where the plate-shaped electrode cleaning portions 34, 34 are separated (state B). Move to the other end side (state C) of the plate electrode 151. As described above, the guide portions 141 move the plate-shaped electrode cleaning portions 34, 34 from the home position state A to the opposite side state C without contacting the plate-shaped electrodes 151 with a certain interval therebetween. I do. Then, in the state C, since the guide of the guide part 141 is lost, the first block 101 of the holding part 138 and the second block
The blocks 102 are in contact with each other and the plate-shaped electrode cleaning unit 13
4, 134 are sandwiched from both sides of the plate-shaped electrode 151.

Conversely, from the above state C, the home position
When returning to (state A), the holding unit 138 is moved by the moving means.
In conjunction with the movement of the plate-shaped electrode cleaning units 134, 1
34 moves to the home position side. At this time, since the first and second guide plates 142 and 143 of the guide portion 141 are open, the contact surfaces of the plate-shaped electrode cleaning portions 134 and 134 move while being in contact with the plate-shaped electrode 131, and eventually reach the home position. (State A) is reached. Then, when the plate-shaped electrode cleaning units 134 and 134 return to the home position (state A), the plate-shaped electrode cleaning units 134 and 134 enter a state A in which the plate-shaped electrode 151 is sandwiched from both sides.

As described above, the tip of the needle electrode portion 151b of the plate electrode 151 facing the latent image carrier 1 (shown in FIG. 1) is positioned in one longitudinal direction of the latent image carrier 1 (see FIG. 10). In the case where the plate electrode 151 is inclined only to the lower left and the plate electrode cleaning unit 134 can move by contacting the plate electrode 151 with the plate electrode cleaning unit 134, the needle electrode facing the latent image carrier 1 of the plate electrode 151. The tip of the portion 151b moves while contacting in a tilted direction. Thereby, the needle electrode portion 1 of the plate electrode 151 is formed.
The direction of stress applied to the tip of 51b and the plate-like electrode 151
Of the tip of the needle electrode portion 151b of the plate electrode 151 corresponds to the direction in which the contact surface of the plate electrode cleaning portions 134, 134 moves while contacting the plate electrode 131. Without damaging the distal end portion and moving the plate-shaped electrode cleaning portions 134 and 134 relatively to the plate-shaped electrode 151, a strong frictional force is generated at the contact surfaces of the plate-shaped electrodes 151. It is possible to remove extraneous matter adhering to.

Therefore, according to the above-described corona discharge device, when the plate-shaped electrode cleaning unit 134 is moved to clean the plate-shaped electrode 151, the moving unit moves the plate-shaped electrode 151.
Since the plate-shaped electrode cleaning portions 134 and 134 are moved only in one of the directions along the longitudinal direction of the plate 51, the tip of the plate-shaped electrode 151 is inclined by inclining the tip shape of the plate-shaped electrode 151 in the moving direction. It is possible to prevent the tip of the electrode portion 151b from being damaged.

Further, a pair of plate-shaped electrode cleaning portions 134 and 13 in which respective contact surfaces contact both side surfaces of the plate-shaped electrode 151, respectively.
By virtue of 4, it is possible to effectively remove deposits such as discharge products and toner from both sides of the plate-like electrode 151.

Further, the plate-shaped electrode cleaning units 134, 134
Is moved to clean the plate electrode 151, the stress applied to the tip of the plate electrode 151 is dispersed in the direction in which the tip of the needle electrode 151b of the plate electrode 151 is inclined. Breakage of the tip of 151b can be prevented.

[0059]

As is clear from the above, according to the present invention, the dirt due to silicon, toner, paper powder and the like adhering to the tip portion of the plate-like electrode formed in a sawtooth shape is removed by the plate-like electrode cleaning unit. Even if a material such as a flocked material is used for the plate-shaped electrode cleaning unit, the plate-shaped electrode can be reliably removed without damaging the tip portion thereof.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an image forming apparatus using a corona discharge device according to a first embodiment of the present invention as a charging device.

FIG. 2 is a perspective view schematically showing the charging device.

FIG. 3 is a detailed perspective view of a main part including a plate-shaped electrode cleaning unit of the charging device.

FIG. 4 is a view of the plate-like electrode and the plate-like electrode cleaning unit as viewed from a discharge direction side.

FIG. 5 is a side view showing a state in which the plate-shaped electrode cleaning unit is in contact with one side surface of the plate-shaped electrode.

FIG. 6 is a perspective view schematically showing a corona discharge device according to a second embodiment of the present invention.

FIG. 7 is a perspective view of a main part including a plate-shaped electrode cleaning unit of the corona discharge device.

FIG. 8 is a view of a plate-like electrode and a plate-like electrode cleaning unit of the corona discharge device as viewed from a needle electrode unit side.

FIG. 9 is a side view of a state in which a plate-shaped electrode cleaning unit of the corona discharge device is in contact with a side surface of the plate-shaped electrode.

FIG. 10 is a schematic diagram of a guide unit when the plate-shaped electrode cleaning unit operates.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Latent image carrier, 3 ... Charging device, 4 ... Exposure device, 5 ... Developing device, 6 ... Transfer device, 20 ... Fixing device, 30, 130 ... Electrode cleaning device, 31, 151 ... Plate electrode, 31a, 151a: base, 31b, 151b: needle electrode, 32,132: discharge stabilizing plate, 33,133: control electrode, 34,134: plate-shaped electrode cleaning unit, 35: moving means, 38,138: holding unit, 39 ... ball bearing part, 40 ... ball screw, 141 ... guide part.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Akira Hirota 2-3-1, Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Prefecture Osaka International Building Minolta Co., Ltd. F-term (reference) 2H200 FA02 FA08 HA12 HA28 HB06 LB02 LB08 LB13

Claims (6)

[Claims] 1. A plate-like electrode formed in a sawtooth shape, a plate-like electrode cleaning unit having a convex-curved contact surface that contacts at least one side surface of the plate-like electrode, and the plate-like electrode cleaning unit. Moving means for moving the plate-shaped electrode along the longitudinal direction thereof. 2. The corona discharge device according to claim 1, wherein the moving unit moves the plate-shaped electrode cleaning unit to clean the plate-shaped electrode, and moves along a longitudinal direction of the plate-shaped electrode. A corona discharge device wherein the plate-shaped electrode cleaning unit is moved in only one of the directions. 3. A plate-like electrode formed in a sawtooth shape, a plate-like electrode cleaning unit having a contact surface in contact with at least one side surface of the plate-like electrode, and the plate-like electrode cleaning unit comprising the plate-like electrode. Moving means for moving along the longitudinal direction of the plate-shaped electrode, wherein the moving means moves the plate-shaped electrode cleaning unit to clean the plate-shaped electrode in a direction along the longitudinal direction of the plate-shaped electrode. A corona discharge device characterized in that the plate-shaped electrode cleaning section is moved to only one side. 4. The corona discharge device according to claim 3, wherein a contact surface of the plate-shaped electrode cleaning portion that contacts a side surface of the plate-shaped electrode has a convex curved shape. 5. The corona discharge device according to claim 1, wherein the plate-shaped electrode cleaning unit is a pair of plate-shaped electrode cleaning units that contact both side surfaces of the plate-shaped electrode. A corona discharge device characterized by the above-mentioned. 6. The corona discharge device according to any one of claims 2 to 5, wherein the plate-shaped electrode is formed in a long plate-like base and a sawtooth shape on one long side of the base. And a tip of the needle electrode portion of the plate-shaped electrode is inclined in a moving direction when the plate-shaped electrode is cleaned by the plate-shaped electrode cleaning portion. Corona discharge device.