JP2001142284A - Corona electrifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corona electrifier which is excellent in durability because of the prolonged life of a cleaning member for cleaning an electrifying wire and in which the electrifying wire can be cleaned thoroughly. SOLUTION: When a supporting base 92 moves back and forth along the electrifying wire 62, a grip plate 96 and a cleaning pad 98 also move back and forth together with the base 92. When the base 92 moves in a forward direction (direction shown by an arrow D), the plate 96 butts the side wall 92a of the base 92, and the wire 62 and the pad 98 come in contact with each other on a contact surface 98a shown by a broken line. Meanwhile, when the base 92 changes its moving direction from the forward direction to a backward direction, the plate 96 butts the side wall 92b of the base 92, and the wire 62 and the pad 98 come in contact with each other on a contact surface 98b shown by a broken line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona charger for charging an image carrier such as a photosensitive drum.

[0002]

2. Description of the Related Art As an output device of a computer or a workstation, an electrophotographic image forming apparatus for forming an image on a recording medium using a developer (toner) or the like is known. This electrophotographic image forming apparatus will be described with reference to FIG.

FIG. 4 is a schematic diagram showing a schematic configuration of an electrophotographic image forming apparatus.

On the top surface of the copier 10, an original cover plate 12 that can be opened and closed is arranged. An operation panel display (not shown) for inputting the number of copies and the like is arranged on the front side of the top surface. Further, the copying machine 10 includes a universal cassette 16 for storing a plurality of cut sheets.
0 is provided so that it can be freely inserted and removed from the front side of the main body. On the right side wall of the copying machine 10, a rectangular manual tray 18 that can feed small-sized recording paper such as a postcard is formed. The manual feed tray 18 rotates in the direction of arrow C about the lower side 18a and opens to a position where a recording medium can be placed (a position indicated by a two-dot chain line). The left side wall of the copying machine 10 is provided with a paper discharge tray 20 on which recording paper on which an image is formed is stacked.

The original 2 is placed under the original cover 12.
A document table glass 26 on which the document 4 is placed is arranged. The original 24 is placed on the original platen glass 26 so that the image surface faces down, and the original 24 is pressed and fixed by the original cover plate 12.
The image recorded on the document 24 is a light source lamp (not shown).
A light (indicated by a broken line A) carrying information of an image read by a known optical system 28 having an image recorded on a document is obtained. This light is applied to the photosensitive drum 32 uniformly charged by the primary charger (corona charger) 30 to form an electrostatic latent image. This electrostatic latent image is developed with the developer (toner) supplied from the developing unit 34 to form a developed image. On the other hand, a recording medium such as recording paper sent out from the universal cassette 16 is fed in the direction of arrow B, and is transferred by the transfer charger (corona charger) 36 to the photosensitive drum 32.
The upper developed image is transferred to a recording medium.

The recording medium on which the developed image has been transferred is conveyed to a fixing device 40 by a conveying device 38. The fixing device 40 is provided with a heat roller 42 and a press roller 44. The recording medium is conveyed while being sandwiched between these two rollers 42, 44, and the developed image is fixed on the recording medium. The recording medium on which the developed image has been fixed in this manner is discharged and stacked on the discharge tray 20. The toner remaining on the photosensitive drum 32 after the transfer is scraped off by the cleaning device 46. Also, the recording medium can be fed from the manual feed tray 18, and the procedure for forming an image on the recording medium fed from the manual feed tray 18 is the same as described above.

The above-described primary charger 30 and transfer charger 36
The corona charger, for example, applies a voltage to a charging wire extending in a predetermined direction to ionize air around the charging wire, thereby uniformly charging the surface of the photosensitive drum 32, or a photosensitive drum, for example. The developer (toner) on the surface of the recording medium 32 is transferred to a recording medium (transfer material). When such a corona charger is used for a long period of time, the charging wire is contaminated with toner (developer) or dust. When the charging wire is contaminated in this way, charging efficiency decreases. In addition, unevenness may occur in the discharge from the charging wire, and for example, the surface of the photosensitive drum 32 may not be uniformly charged.

Therefore, a technique for cleaning a dirty charged wire has been conventionally proposed. A corona charger provided with a cleaning member for cleaning a charging wire will be described with reference to FIGS.

FIG. 5 is a perspective view showing a schematic configuration of a corona charger provided with a cleaning member for cleaning a charging wire. FIG. 6 is a schematic diagram illustrating the cleaning member.

The overall shape of the corona charger 50 is a box extending in the direction of the rotation axis of the photosensitive drum 32 (the direction perpendicular to the plane of FIG. 4). The corona charger 50 has a shield plate having a pair of side walls 52 and 54 and a bottom wall 56 extending and extending in the rotation axis direction and having an open upper surface. Side walls 52, 5
4 and the bottom wall 56 at the both ends in the longitudinal direction are blocks 5 respectively.
8 and 60 are fixed.

A charging wire 62 is located between the pair of side walls 52 and 54 described above. Both ends in the longitudinal direction of the charging wire 62 are fixed to the blocks 58 and 60 via tension springs (not shown) or the like. For this reason, the charging wire 62 is in a tensioned state (a state in which it is pulled) without loosening.

A cleaning device 70 for cleaning the charging wire 62 is disposed near the charging wire 62.
The cleaning device 70 has a screw shaft 72 in which a spiral groove is formed. The screw shaft 72 is slightly longer than the charging wire 62 and extends below the charging wire 62 substantially parallel to the charging wire 62. A support table (carriage) 74 having a screw formed on the inner surface is engaged with the screw shaft 72. The support base 74 is movably fixed to a pair of rails 76 having a U-shaped cross section and parallel to the screw shaft 72. Therefore,
By rotating the screw shaft 72 with a motor (not shown) or the like, the support base 74 is guided by the pair of rails 76 and moves along the charging wire 62. By switching the rotation direction of the screw shaft 72, the support table 74 reciprocates along the charging wire 62.

A cleaning pad 78 for fixing the charging wire 62 from both sides thereof and cleaning the charging wire 62 is fixed to the upper surface of the support base 74. Accordingly, by reciprocating the support base 74 along the charging wire 62, the cleaning pad 78 reciprocates while holding the charging wire 62 from both sides and in contact with the charging wire 62, so that the developer adhering to the charging wire 62 can be removed. The dust and the like are removed, and the charging wire 62 is cleaned.

[0014]

However, since the cleaning pad 78 is fixed to the support 74, the cleaning pad 7 is not fixed.
8, the contact surface that contacts the charging wire 62 is always the same surface. For this reason, only a small part of the contact surface of the cleaning pad 78 is used, so that this contact surface wears quickly and the cleaning pad 78 may be locally deformed or missing relatively early. is there. Due to such deformation or omission, the contact pressure when the cleaning pad 78 sandwiches the charging wire 62 is weakened, and the charging wire 62 may not be sufficiently cleaned. In this case, the discharge from the charging wire 62 may be uneven, and for example, the surface of the photosensitive drum 32 may not be uniformly charged.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a corona charger which has a long life and excellent durability of a cleaning member for cleaning a charging wire and can clean a charging wire neatly.

[0016]

In order to achieve the above object, a corona charger according to the present invention forms an electrostatic latent image on an image carrier and supplies a developer to the electrostatic latent image to form a developed image. To form
(1) In a corona charger for applying a voltage to a charging wire extending in a predetermined direction to charge a predetermined member in an image forming apparatus for forming an image by transferring the developed image to a recording medium in a predetermined transfer area, A cleaning member is provided that moves along the charging wire while cleaning the charging wire while contacting the charging wire, and cleans the charging wire and changes a contact surface that contacts the charging wire at a predetermined timing. .

In this case, the cleaning member includes (2)
The contact surface may be reciprocated along the charging wire, and the contact surface may be changed at a timing of changing a moving direction during the reciprocation.

The cleaning member may change the contact surface by (3) changing a posture by a contact resistance when the cleaning member comes into contact with the charging wire.

Further, the cleaning member includes:
The contact surface may be changed by rotating and contacting the charging wire.

Further, the cleaning member includes:
(5) The cleaning member may be rotated by contact resistance when the cleaning member comes into contact with the charging wire to change the contact surface.

As the cleaning member, an elastic material such as rubber containing a polishing agent, sponge, or maltprene is used.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a corona charger according to the present invention will be described with reference to FIGS.

FIG. 1 is a schematic view showing a corona charger of the first embodiment, and FIG. 2 is an enlarged view of a cleaning member of the corona charger of FIG. 1. FIG. FIG. 3B is a schematic view showing a cleaning pad when returning. In these drawings, the same components as those shown in FIGS. 5 and 6 are denoted by the same reference numerals.

In the corona charger 80, a cleaning device 90 for cleaning the charging wire 62 is arranged near the charging wire 62. The cleaning device 90 has a screw shaft 72 in which a spiral groove is formed. The screw shaft 72 is slightly longer than the charging wire 62 and extends below the charging wire 62 substantially parallel to the charging wire 62. A support base (carriage) 92 having a screw formed on the inner surface of the screw shaft 72.
Are engaged. The support base 92 is movably fixed to a pair of rails 76 (see FIG. 5) having a U-shaped cross section and parallel to the screw shaft 72. Therefore, when the screw shaft 72 is rotated by the motor 59 or the like, the support base 92 is guided by the pair of rails 76 and moves along the charging wire 62.
By rotating the motor 59 forward and reverse to switch the rotation direction of the screw shaft 72, the support base 92 reciprocates along the charging wire 62.

A concave portion is formed in the upper part of the support base 92, and a shaft 94 extending in a direction perpendicular to the screw shaft 72 is arranged in the concave portion. The shaft 94 has a support base 92.
A grip plate 96 whose posture changes during the reciprocating movement of is held rotatably. On the upper surface of the grip plate 96, a cleaning pad 98 (an example of a cleaning member according to the present invention) for sandwiching and cleaning the charging wire 62 is fixed. The contact pressure when the cleaning pad 98 comes into contact with the charging wire 62 is a pressure at which the developer and dust attached to the charging wire 62 are rubbed off by the cleaning pad 98. As the cleaning pad 98, one having both elasticity and polishing ability, such as rubber containing an abrasive, is used. Instead of rubber, sponge, maltprene, or the like may be used.

As described above, the support base 92 is connected to the charging wire 6.
Reciprocate along 2. During this reciprocation, the grip plate 96 and the cleaning pad 98 reciprocate together with the support base 92. When the support base 92 moves in the outward path (the direction of the arrow D), the cleaning pad 98 and the grip plate 96 are inclined by the contact resistance between the charging wire 62 and the cleaning pad 98, and the grip plate 96 hits the side wall 92a of the support base 92, In this state, the cleaning pad 98 moves in the direction of arrow D. Accordingly, the charging wire 62 and the cleaning pad 98 are separated from each other by the contact surface 98 shown by a broken line.
a will come into contact.

When the motor 59 rotates in the reverse direction and the support base 92 changes its moving direction from the forward path to the backward path, the cleaning pad 98 and the grip plate 96 are inclined by the angle θ due to the contact resistance when the cleaning pad 98 comes into contact with the charging wire 62. Change his posture. The grip plate 96 abuts against the side wall 92b of the support base 92, and the cleaning pad 98 moves in the direction of arrow E in this state. Therefore, the charging wire 62 and the cleaning pad 98
Will come into contact on the contact surface 98b indicated by the broken line.

As described above, the contact surfaces 98a and 98b change at the timing of changing the moving direction when reciprocating.
The same surface does not keep in contact with the charging wire 62. As a result, the cleaning pad 98 is less likely to be locally worn,
The service life of the corona charger 80 as well as the cleaning pad 98 is extended, and the durability is improved. In addition, since the contact surfaces 98a and 98b change between the forward path and the return path, the charging wire 62 is cleanly cleaned.

Referring to FIG. 3, a second embodiment of the corona charger of the present invention will be described.

FIG. 3A is a schematic diagram showing a corona charger of the second embodiment, and FIG. 3B is an enlarged schematic diagram showing a cleaning member of the corona charger of FIG. .
In this figure, the same components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

In the corona charger 100, the charging wire 62
A cleaning device 110 for cleaning is disposed near the charging wire 62. The cleaning device 110 has a screw shaft 72 in which a spiral groove is formed. Screw shaft 72
Is slightly longer than the charging wire 62 and extends below the charging wire 62 almost in parallel with the charging wire 62. Screw shaft 7
2 is a support table (carriage) having a screw formed on the inner surface
112 are engaged. The support base 112 is movably fixed to a pair of rails 76 (see FIG. 5) having a U-shaped cross section and parallel to the screw shaft 72. Therefore, the screw shaft 72
Is rotated by the motor 59 or the like, the support base 112 is guided by the pair of rails 76 and moves along the charging wire 62. By switching the rotation direction of the screw shaft 72 by rotating the motor 59 forward and backward, the support base 112 reciprocates along the charging wire 62.

From the upper surface of the support base 112, the grip plate 11
4, a disc-shaped cleaning pad 116 (an example of a cleaning member according to the present invention) is rotatably fixed above the grip plate 114.
The cleaning pad 116 cleans by sandwiching the charging wire 62. The contact pressure when the cleaning pad 116 contacts the charging wire 62 is a pressure at which the developer and dust adhering to the charging wire 62 are scraped off by the cleaning pad 116. As the cleaning pad 116, one having both elasticity and polishing ability, such as rubber containing an abrasive, is used. Instead of rubber, sponge, maltprene, or the like may be used.

As described above, the support base 112 reciprocates along the charging wire 62. During this reciprocation, the cleaning pad 116 rotates due to the contact resistance with the charging wire 62. When the support base 112 moves in the direction of arrow D (direction of arrow E), the cleaning pad 116 rotates in the direction of arrow D '(direction of arrow E'). Therefore, the contact surface 116a where the cleaning pad 116 contacts the charging wire 62 always changes.

Since the contact surface 116a changes when the support base 112 reciprocates in this manner, the same surface is
Never keep in contact with As a result, the cleaning pad 11
6 is less likely to be locally worn, so that the service life of the corona charger 100 as well as the cleaning pad 116 is extended, and the durability is improved. In addition, since the contact surface 116a changes, the charging wire 62 is cleanly cleaned.

[0035]

As described above, in the corona charger of the present invention, the contact surface that contacts the charging wire changes at a predetermined timing, so that a certain surface does not continue to contact the charging wire. For this reason, there is no possibility that only a certain surface of the cleaning member is worn down intensively and the cleaning member cannot be used in a short period of time (the service life is shortened). Also,
Since the contact surface changes, the charged wire is cleaned with a new contact surface. Therefore, the life of the cleaning member is extended, the durability is improved, and the charging wire can be cleaned cleanly.

Here, if the cleaning member reciprocates along the charging wire and changes the contact surface at the timing of changing the direction of movement during the reciprocation, the contact surface is changed between the forward path and the return path. As a result, the life of the cleaning member is extended, the durability is improved, and the charged wire can be cleaned cleanly.

In the case where the cleaning member changes the contact surface by changing the posture by the contact resistance when the cleaning member contacts the charging wire, the contact surface is changed using the contact resistance. No need for parts or equipment to change the contact surface
Accordingly, the configuration becomes simple.

Further, if the cleaning member changes its contact surface by rotating and contacting the charging wire, the contact surface always changes.
The service life of the cleaning member is further extended, the durability is further improved, and the charged wire can be more thoroughly cleaned.

Further, when the cleaning member is rotated by the contact resistance when the cleaning member comes into contact with the charging wire to change the contact surface, the cleaning member is rotated by using the contact resistance. Since the surface is changed, parts and devices for changing the contact surface are unnecessary,
Accordingly, the configuration becomes simple.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a corona charger of a first embodiment.

2A and 2B are enlarged views of a cleaning member of the corona charger of FIG. 1; FIG.
(B) is a schematic diagram showing a cleaning pad at the time of a return trip.

FIG. 3A is a schematic diagram illustrating a corona charger of a second embodiment, and FIG. 3B is an enlarged schematic diagram illustrating a cleaning member of the corona charger of FIG.

FIG. 4 is a schematic diagram illustrating a schematic configuration of an electrophotographic image forming apparatus.

FIG. 5 is a perspective view showing a schematic configuration of a conventional corona charger provided with a cleaning member for cleaning a charging wire.

FIG. 6 is a schematic diagram illustrating the cleaning member of FIG. 5;

[Explanation of symbols]

 62 Charging wire 80, 100 Corona charger 90, 110 Cleaning device 98, 116 Cleaning pad 98a, 98b, 116a Contact surface

Claims (5)

[Claims] An electrostatic latent image is formed on an image carrier, a developer is supplied to the electrostatic latent image to form a developed image, and the developed image is transferred to a recording medium in a predetermined transfer area. In a corona charger for applying a voltage to a charging wire extending in a predetermined direction to charge a predetermined member in an image forming apparatus for forming an image, the corona charging device moves along the charging wire while contacting the charging wire. A corona charger comprising: a cleaning member that cleans a wire and changes a contact surface that contacts the charging wire at a predetermined timing. 2. The cleaning device according to claim 1, wherein the cleaning member reciprocates along the charging wire, and changes the contact surface at a timing of changing a moving direction during the reciprocation. Corona charger. 3. The corona according to claim 2, wherein the cleaning member changes the contact surface by changing a posture by a contact resistance when the cleaning member contacts the charging wire. Charger. 4. The corona charger according to claim 1, wherein the cleaning member changes the contact surface by rotating and contacting the charging wire. 5. The corona charger according to claim 4, wherein the cleaning member is rotated by contact resistance when the cleaning member contacts the charging wire to change the contact surface. .