Electrification device, and image forming apparatus

Abstract

A needle electrode and a cleaning member are provided. A plurality of needles are arrayed upon the needle electrode in a straight line, and protrude towards a surface of a photoreceptor. The cleaning member is disposed movably along the array direction of the plurality of needles between the surface of the photoreceptor and the needle electrode. When the cleaning member moves, the tip portion of each of the plurality of needles in the arranged order, after having been embedded from the surface of the cleaning member into its interior, then exits to the exterior of the cleaning member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an image forming apparatus to which a charging device according to an embodiment of the present invention is applied;

FIG. 2A is a front sectional view of a principal portion of the charging device, and FIG. 2B is a side view of the portion;

FIG. 3 is a figure showing a cleaning operation by a cleaning roller;

FIG. 4 is a figure showing the length by which the needles of the needle electrode are embedded in the cleaning roller;

FIG. 5 is a side view of the charging device; and

FIG. 6 is a side view of the charging device according to another embodiment of the present invention.

Claims

1. A charging device, comprising: a needle electrode in which a plurality of needles that protrude towards a surface of a photoreceptor are arrayed in a straight line; anda cleaning member that is disposed between the photoreceptor surface and the needle electrode so as to be movable along an array direction of the plurality of needles;wherein, during a movemnt of the cleaning member, after a tip portion of each of the plurality of needles in order has been embedded from the surface of the cleaning member into the interior thereof, the tip portion exits to the exterior of the cleaning member.

2. A charging device as described in claim 1, further comprising: a holder that holds the needle electrode and whose cross sectional shape orthogonal to the array direction is constant, at least within the range of the array direction over which the plurality of needles are arrayed; anda support element that is held by the holder arranged so as to restrict its movement in directions orthogonal to the array direction, and that supports rotatably the cleaning member.

3. A charging device as described in claim 2, wherein, during the cleaning member is moving, at least one of the plurality of needles is embedded in the interior of the cleaning member.

4. A charging device as described in claim 2, further comprising a shaft member, a first end portion of which is fixed to the support element and a second end portion of which is exposed at a front end portion of the holder, and that is supported at two spots of the holder along the array direction so as to be movable in the array direction.

5. A charging device as described in claim 3, further comprising a shaft member, a first end portion of which is fixed to the support element and a second end portion of which is exposed at a front end portion of the holder, and that is supported at two spots of the holder along the array direction so as to be movable in the array direction.

6. A charging device as described in claim 2, further comprising a threaded rod that is supported by the holder so as to be rotatable around an axis parallel to the array direction, and that has a screw portion whose length is equal to or longer than the array range; a screw element that is fixed to the support element and is engaged over the threaded rod; anda drive source that supplies rotation in both forward and reverse directions to the threaded rod.

7. A charging device as described in claim 3, further comprising a threaded rod that is supported by the holder so as to rotate freely around an axis parallel to the array direction, and that has a screw portion whose length is at least equal to the array range; a screw element that is fixed to the support element and is engaged over the threaded rod; anda drive source that supplies rotation in both forward and reverse directions to the threaded rod.

8. A charging device as described in claim 1, wherein the cleaning member is set to a wait position within a range of the array direction outside the image formation region of the photosensitive surface.

9. A charging device as described in claim 1, wherein the cleaning member is made from an elastic material that contains a polishing material whose hardness is lower than that of the raw material of the needles.

10. An image forming apparatus that performs image formation by a method of electronic photography via a photosensitive element, comprising an electrification device as described in claim 1.