JP5285238B2 - Scorotron charger for image forming equipment - Google Patents

Description

  The present invention relates to a scorotron charger provided to face a photoreceptor of an image forming apparatus and used for main charging or transfer charging. More specifically, the present invention relates to a grid of a scorotron charger, a surface of the photoreceptor, and The present invention relates to a scorotron charger for an image forming apparatus capable of easily adjusting the distance between the two.

In electrophotographic image forming apparatuses such as copiers, family machines, printers, and MFPs, the main charger uniformly charges the photoconductor positively or negatively, and image exposure is performed by light irradiation based on predetermined image information. Then, an electrostatic latent image is formed, and this electrostatic latent image is developed by a developing method such as a magnetic brush developing method, and a toner image is formed on the surface of the photoreceptor.
The toner image formed on the surface of the photoconductor is transferred to transfer paper using an electrostatic force using a transfer device, and the transfer paper onto which the toner image has been transferred is introduced into a fixing device, and the toner image is generated by heat and pressure. Is fixed on the surface of the transfer paper to form an image. On the other hand, after the transfer is completed, the toner remaining on the surface of the photosensitive member is cleaned by a cleaning device, and further, static elimination is performed as necessary. Thus, one cycle of the image forming process is completed, and the next image formation is performed.

  As the main charging device as described above, a scorotron charger is widely used. In this scorotron charger, a grid is provided on the discharge opening surface of the shield case where the corona wire is stretched, and due to the potential difference between the corona wire and the grid, corona discharge is generated from the corona wire to the surface of the photoconductor via the grid. And the surface of the photoreceptor is charged to a predetermined potential having a predetermined polarity. In such a scorotron charger, in order to perform uniform charging, it is necessary to keep a constant distance between the surface of the photoreceptor and the grid. For this purpose, a charging unit including a scorotron charger and a roller contacting the surface of the photosensitive member are provided, and the distance between the grid of the scorotron charger and the surface of the photosensitive member is kept constant by the roller. In addition, it is known that when the surface potential of the scorotron charger varies, rollers of different outer diameters are used to uniformly correct the surface potential.

FIG. 15 is a perspective view of such a scorotron charger, and FIGS. 16A and 16B show a gap roller and a height adjusting member for maintaining a constant distance between the grid of the scorotron charger and the surface of the photoreceptor. Indicates.
As shown in FIG. 15, two gap rollers 60 and 61 are arranged in parallel along the longitudinal direction of the shield case 31 at the end of the scorotron charger 30. These gap rollers 60 and 61 have different outer diameters, one gap roller 60 has a large outer diameter, and the other gap roller 61 has a small outer diameter.

The gap rollers 60 and 61 are supported at both ends of the central shafts 60a and 61a by bearing members 62 and 64, respectively. The bearing members 62 and 64 each have a pair of bearing plates 70 and 70 that face each other, and the bearing plate 70 has a concave portion for bearing.
The bearing recess opens downward in FIG. 16, and includes an upper retraction fitting recess 72a and a lower positioning fitting recess 72b. That is, both ends of the central shafts 60a and 61a of the gap rollers 60 and 61 are fitted and supported in either the retracting fitting recess 72a or the positioning fitting recess 72b.

With such a configuration, when the central shaft 60a of the gap roller 60 having a large outer diameter is fitted into the positioning fitting recess 72b, the distance between the photosensitive member surface and the grid 35 is increased. On the other hand, when the center shaft 61a of the gap roller 61 having a small outer diameter is fitted into the positioning fitting recess 72b, the distance between the photosensitive member surface and the grid 35 is reduced.
Thus, by appropriately switching the gap rollers 60 and 61 fitted in the positioning fitting recess 72b, the distance between the surface of the photoreceptor and the grid 35 can be easily adjusted.
Japanese Patent No. 3694500

As described above, in the scorotron charger of Patent Document 1, as a method for adjusting to an appropriate surface potential, adjustment is performed by selecting an appropriate one in combination with rollers having different outer diameters, or by removing the rollers. A method of selecting and replacing a plurality of different outer diameters is employed. By bringing the roller into contact with the photosensitive member, it is possible to cope with a change in the circumferential position of the rotating photosensitive member.
However, in the technique of Patent Document 1, the number of rollers accommodated in the unit is limited to about 2 to 3, and the range of adjustment is limited. Further, in the method of exchanging the rollers, there is a problem that workability is deteriorated because an operation of removing the rollers from the charger occurs in order to replace the rollers.
The present invention has been made in view of such circumstances, and can easily adjust the gap between the grid and the surface of the photosensitive member, and can also adjust the surface potential variation in the axial direction of the photosensitive member. An object of the present invention is to provide a scorotron charger for an image forming apparatus that can be easily and precisely performed.

In order to achieve the above object, a scorotron charger of an image forming apparatus according to the present invention includes a corona wire stretched in a conductive shield case, and a grid disposed at a distance from the corona wire. A charging housing for supporting the grid is provided at an end of the shield case, and the charging housing accommodates a gap roller contacting the peripheral surface of the photosensitive member, and a rotating shaft of the gap roller is connected to the charging shaft. In a scorotron charger of an image forming apparatus held by a bearing of a bearing member disposed in a housing, the bearing member is disposed so as to be movable relative to the charging housing, and the bearing member is disposed in the charging housing. disposed position adjustment member for the relatively movable to the charging housing, said positioning member, the bottom of the charging housing The curved surface of the rotatably disposed by different curvatures on the eccentric shaft or concentric radius a circular plate member having a plurality, and so as to abut against the outer peripheral surface of the circular plate to the bearing member.
In the scorotron charger of the image forming apparatus, a hole is formed in the bottom surface of the shield case and the charging housing, and an outer peripheral portion of the disk material is disposed in the hole and protrudes outward from the bottom surface of the shield case. be able to.
The scorotron charger of the image forming apparatus can be provided with a position indication for identifying the size of the gap between the photoconductor and the grid on the outer peripheral portion or the outer peripheral side surface of the disc material.
In order to achieve the above object, the scorotron charger of the image forming apparatus according to the present invention is provided with a corona wire stretched in a conductive shield case, and spaced apart from the corona wire. And a charging housing that supports the grid is provided at an end of the shield case. The charging housing contains a gap roller that abuts on the circumferential surface of the photosensitive member, and a rotation shaft of the gap roller In a scorotron charger of an image forming apparatus held by a bearing of a bearing member disposed in the charging housing, the bearing member is disposed so as to be movable relative to the charging housing, and the bearing is disposed in the charging housing. disposed position adjustment member for the member to be relatively movable to the charging housing, said positioning member, said charging housing A slide plate formed with slidably disposed a stepped surface on the bottom, the step of the stepped surface and so as to slide on the bearing member.
The scorotron charger of the image forming apparatus forms a slide knob on the slide plate, and projects the knob from the slide hole formed on the bottom surface of the shield case and the charging housing to the outside of the shield case. I made it.
The scorotron charger of the image forming apparatus is provided with a position display for identifying the size of the gap between the photoconductor and the grid in the slide hole on the bottom surface of the shield case.

  In other words, according to the scorotron charger of the present invention, a corona wire stretched in a conductive shield case and a grid provided on the discharge opening surface of the shield case are arranged facing the photoconductor. In the scorotron charger, a gap roller is accommodated at the end of the shield case, and both ends of the central shaft are held by bearing members. In the vicinity of the bearing member, the bearing member height adjustment mechanism is provided on the side facing the gap roller, that is, on the side facing the shield case opening, and by operating the adjustment mechanism from the outside of the charger, The roller height can be adjusted. Thereby, it is not necessary to prepare a plurality of rollers for adjustment, and adjustment can be easily performed.

In the scorotron charger of the image forming apparatus of the present invention, the bearing member is disposed so as to be relatively movable with respect to the charging housing, and a position adjusting member for allowing the bearing member to be relatively moved with respect to the charging housing is provided with the charging housing. Therefore, the gap between the photosensitive drum and the grid can be adjusted. The position adjusting member is a disc material having a plurality of curved surfaces with different curvature radii on an eccentric shaft or a concentric circle, which is rotatably arranged at the bottom of the charging housing, in the scorotron charger of the image forming apparatus. And since the outer peripheral surface of the said disc material was made to contact | abut to the said bearing member, a gap adjustment can be easily performed by rotating a disc material.
In addition, a hole is formed in the bottom surface of the shield case and the charging housing, and an outer peripheral portion of the disc material is disposed in the hole and protrudes outward from the bottom surface of the shield case. The gap can be easily adjusted by rotating the disc material from the above.
Furthermore, since the position display for identifying the size of the gap between the photoconductor and the grid is provided on the outer peripheral portion or the outer peripheral side surface of the disc material, the gap adjustment amount can be recognized.
The scorotron charger of another image forming apparatus of the present invention is a slide plate in which the height adjusting member is a slide plate in which the position adjusting member is formed to be slidably disposed on the bottom of the charging housing. Te, in the step of the stepped surface was slid on the bearing member, by sliding the slide plate, it is possible to easily adjust the gap.
The scorotron charger of the image forming apparatus includes a slide knob formed on the slide plate, and the knob protrudes outside the shield case from a slide hole formed on a bottom surface of the shield case and the charging housing. Therefore, the gap can be easily adjusted by moving the knob from the outside of the scorotron charger.
Further, the scorotron charger of the image forming apparatus is provided with a position indication for identifying the size of the gap between the photoconductor and the grid in the slide hole on the bottom surface of the shield case, so that the gap adjustment amount is recognized. can do.

The scorotron charger of the image forming apparatus according to the embodiment of the present invention will be described below with reference to the drawings. In this specification, the direction in which the paper feed cassette 3 shown in FIG. 1 is pulled out is the front side (the right side in the drawing), and the width direction of the paper feed cassette 3 is the left and right (the vertical direction of the paper surface in FIG. 1).
First, the internal structure of the image forming apparatus will be briefly described along the sheet flow direction of the image forming apparatus.
As shown in FIG. 1, a paper feed cassette 3 is disposed at the lower part of the apparatus main body 2 of the image forming apparatus 1. Sheets before printing (not shown) are stacked and stored in the sheet feed cassette 3, separated one by one from the sheet feed cassette 3, and sent out to the sheet conveyance path. A pickup roller 5 is disposed at the sheet sending side end of the sheet feeding cassette 3, a sheet feeding roller 7 is disposed at an upper position adjacent to the front side of the sheet feeding cassette 3, and a separation roller is disposed below the sheet feeding roller 7. 8 is disposed.

  On the upstream side of the paper feed roller 7, a transport roller 11 and registration rollers 12 and 13 disposed above and below are provided, and these rollers 11 to 13 are rotationally driven by a driving means (not shown). The registration rollers 12 and 13 feed the sheet toward the image forming unit 18 in synchronization with a toner image formed by the image forming unit 18 described later while correcting the oblique feeding of the sheet. A registration switch 15 is disposed between the conveyance roller 11 and the registration rollers 12 and 13.

  The image forming unit 18 includes a photosensitive drum 19 and a transfer roller 20, and transfers an image onto a sheet conveyed to the image forming unit 18. The photosensitive drum 19 carries a toner image to be formed on the surface thereof. For this purpose, the image forming apparatus 1 further includes a developing unit 21, a cleaning device 17, and a scorotron charger 30 around the photosensitive drum 19. Yes. In the image forming unit 18, the photosensitive drum 19 is charged by the scorotron charger 30, and an electrostatic latent image is created based on the image data written on the photosensitive drum 19 by the optical unit 22. Next, the developing unit 21 develops the toner to visualize the electrostatic latent image with toner, the transfer roller 20 transfers the toner to a transfer material such as paper, and the cleaning device 17 transfers the transfer residual toner to the photosensitive drum 19. It is configured to be removed from the surface.

A fixing unit 23 including a fixing roller 24 and a pressure roller 25 is disposed on the downstream side of the image forming unit 18. The sheet carrying the unfixed toner image in the image forming unit 18 is sent to the fixing unit 23 where the toner image is fixed by the heat roller.
On the further downstream side of the fixing unit 23, an upstream discharge roller pair 26a, 26b and a downstream discharge roller pair 28, 29 are disposed. A sheet discharge port 32 is disposed further downstream of the downstream discharge roller pair 28 and 29.

2 is a perspective view of a main part (one end portion on the bottom side) of the scorotron charger of the present invention, FIG. 3 is an exploded perspective view thereof, and FIG. 4 is a cross-sectional view of the scorotron charger cut in the longitudinal direction. With reference to these drawings, the scorotron charger 30 includes a corona wire 33 (FIG. 4) stretched in a conductive shield case 31 having a U-shaped cross section, and a discharge opening surface of the shield case 31. A grid 35 is provided over substantially the entire surface of 31a. That is, the scorotron charger 30 is arranged so that the above-described discharge opening surface 31a faces the photosensitive drum 19 (see FIG. 1) of the image forming apparatus 1, and applies a high voltage between the corona wire 33 and the grid 35. As a result, corona discharge is performed on the photosensitive drum 19 from the corona wire 33 through the grid 35, thereby charging the surface of the photosensitive member positively or negatively.
For convenience of explanation, the side opposite to the discharge opening 31 a of the shield case 31 having a U-shaped cross section is defined as the bottom of the shield case 31.

At one end of the shield case 31 of the scorotron charger 30, a charging housing 37 made of a substantially box-like electrical insulating member is provided so as to protrude from the inside of the shield case 31 to the outside in the longitudinal direction.
A handle 39 is integrally formed outside the charging housing 37 in the longitudinal direction, and the handle 39 is used when the scorotron charger 30 is attached to or detached from the image forming apparatus 1. The opening of the charging housing 37 is provided on one end side in the longitudinal direction of the grit 35. The end portion 43 of the grid 35 is provided with a roller opening 43a and further on the tip end side to form a hook hole 43b. The charging housing 37 is provided with a roller opening 43a and a gap roller 40 is provided. ing. Further, the charging housing 37 is provided with a fixing device 36 for the corona wire 33 so as to be positioned between the roller opening 43a and the hooking hole 43b, and the hooking claw of the end portion 43 corresponding to the position of the hooking hole 43b. 38 is disposed. The grid 35 is fixed to the charging housing 37 by engaging a hook hole 43 b formed in the end portion 43 with a hook claw 38.
A holder made of a frame-like electrically insulating member is also fitted into the other end portion of the shield case 31.

As described above, the gap roller 40 is disposed in the roller opening 43 a of the charging housing 37.
With reference to FIGS. 5 and 6, the gap roller 40 forms a rotating shaft 40 a that protrudes from the side surface to both sides, and the rotating shaft 40 a is oriented in the extending (longitudinal) direction of the shield case 31. Has been. The rotating shaft 40 a is supported by a bearing 41 a formed on the roller bearing member 41. The bearing 41a is not a circular hole-shaped bearing, but one end side is opened, and the gap roller 40 can be taken in and out from the open portion. The roller bearing member 41 has a substantially block shape, and the pair of side walls 41 b and 41 c are arranged so as to face the opposing walls 37 a and 37 b of the charging housing 37. Rib-shaped guide members 45 (only one of which is shown in FIG. 3) for guiding the side walls 41b and 41c are formed on the opposing walls 37a and 37b.
The height adjusting roller 46 has an outer peripheral surface 50 in contact with driven legs 41 d and 41 e provided at the lower part of the roller bearing member 41. When the height adjustment roller 46 rotates, the outer peripheral surface 50 slides with respect to the driven legs 41d and 41e.

As shown in FIG. 3, the guide member 45 is arranged so that the roller bearing member 41 can be moved up and down in the height direction of the charging housing 37. A height adjustment roller 46 is disposed below the roller bearing member 41. The height adjustment roller 46 is composed of a pair of rollers connected by a rotation shaft 46b. A bearing 47 is formed on the bottom 37c side of the charging housing 37, and the rotation shaft 46b provided on the height adjustment roller 46 is a bearing. 47 is pivotally supported. The height adjusting roller 46 is pivotally supported so as to be rotatable about the rotation shaft 46b.
As shown in FIG. 6, a long hole 48 that accommodates a part of the height adjustment roller 46 is formed in the bottom 37 c of the charging housing 37, and the outer periphery of the height adjustment roller 46 is shielded in the shield case 31. A long hole 49 (see FIG. 8) that protrudes from the bottom wall 31b of the case 31 is formed.

  As shown in FIG. 7, the outer peripheral surface 50 of the height adjusting roller 46 is provided with four regions 50a to 50d at intervals of 90 degrees. Among these regions 50a to 50d, the length (curvature radius) from the center O of the rotation shaft 46b of the height adjusting roller 46 to the outer peripheral surface from the regions 50a to 50d has a relationship of 50a <50b <50c <50d. It is formed to satisfy. Since the rotation shaft 46b of the height adjustment roller 46 is fixed in position, when the height adjustment roller 46 is rotated in the range of each region 50a to 50d, the roller bearing member 41 in contact with the height adjustment roller 46 moves up and down. Can move. In order to change the length of each region of the height adjusting roller 46, in addition to changing the radius of curvature described above, the rotational axis of the height adjusting roller may be decentered or the elliptical shape may be deformed. In the present embodiment, since the gap between the grid 35 and the photosensitive drum 19 is 0.6 to 0.8 mm, the maximum difference in the radius of curvature of the regions 50a to 50d is about 0.2 mm.

  In the outer peripheral portion of the side surface of the height adjustment roller 46, 3 corresponds to the position of the region 50a, 4 corresponds to the position of the region 50b, 1 corresponds to the position of the region 50c, and 1 corresponds to the position of the region 50d. The number 2 is engraved. A groove 50e is formed between the regions 50a to 50d. As shown in FIG. 8, these indentations 1 to 4 are inscribed at positions that can be seen through the long holes 49 when viewing the bottom wall 31 b of the shield case 31. (Hereafter, delete)

2 to 4, in order to set the grid 35 in the shield case 31, the edge of the roller opening 43 a of the attachment end 43 provided at the end of the grid 35 is aligned, and then the hook hole The grid 35 is set on the shield case 31 by hooking 43b on the hooking claws 38. Thus, the grid 35 is assembled to the charging housing 37.
In the scorotron charger 30, the roller opening 43 a is formed at a position where the roller bearing member 41 is disposed. The outer peripheral surface of the gap roller 40 protrudes from the roller opening 43 a, and the photosensitive drum 19. A gap is formed between the scorotron charger 30 (see FIG. 1) and the scorotron charger 30. The gap rollers 40 are provided at both left and right ends of the shield case 31, thereby forming a gap with the peripheral surface of the photosensitive drum 19.

Referring to FIGS. 4 and 6, when the surface potential of the scorotron charger 30 varies, the outer peripheral surface of the height adjusting roller 46 protruding from the bottom wall 31b of the shield case 31 is rotated. The distance between the surface of the photosensitive drum 19 and the grid 35 can be adjusted. That is, when the height adjusting roller 46 is rotated, the side walls 41b and 41c of the roller bearing member 41 in contact with the height adjusting roller 46 are guided by the rib-shaped guide member 45 (see FIG. 3) of the charging housing 37. Can be moved up and down.
With reference to FIGS. 6 and 7, the length (curvature radius) from the center O of the height adjusting roller 46 to the outer peripheral surface from the regions 50a to 50d is, as described above, the relationship of 50a <50b <50c <50d. It is formed to satisfy. Therefore, when the region 50a of the height adjusting roller 46 and the roller bearing member 41 are in contact with each other, the interval between the photosensitive drum 19 and the grid 35 is the smallest, and as the region 50b, 50c, and 50d are sequentially turned, The interval becomes larger.

When the roller bearing member 41 moves up and down by rotating the height adjusting roller 46 as described above, the gap roller 40 is in contact with the photosensitive drum 19, so that the charging housing 37 is relative to the photosensitive drum 19. Move on. Therefore, the grid 35 assembled to the charging housing 37 can also move relative to the photosensitive drum 19. Thus, the scorotron charger can perform uniform charging within a set range.
In order to easily rotate the height adjustment roller 46, it is desirable to confirm the height adjustment roller 46 from the outside and to perform a layout so as to be adjusted with a fingertip. The groove 50e formed between the regions 50a to 50d of the height adjustment roller 46 can be rotated by inserting the tip of the driver into the groove 50e when the fingertip does not reach.

Next, a second embodiment of the present invention will be described. The same parts (same names) as those in the first embodiment will be described with the same reference numerals.
In the first embodiment, the height adjusting roller 46 of the scorotron charger 30 is brought into contact with the driven legs 41d and 41e of the roller bearing member 41 to change the radius of curvature of each of the regions 50a to 50d. The member 41 is moved up and down to adjust the distance between the photosensitive drum 19 and the grid 35. In the scorotron charger of this embodiment, the roller bearing member 41 is moved up and down using a slide plate. . Hereinafter, this structure will be described.

  FIG. 10 is an exploded perspective view of the scorotron charger 30, and FIG. 11 is a cross-sectional view of the scorotron charger 30 cut in the longitudinal direction. The gap roller 40 having the same shape as that of the first embodiment is rotatably supported by the bearing 41a of the roller bearing member 41. The roller bearing member 41 has the same basic shape as that of the first embodiment, except that the lengths of the driven legs 41d and 41e are increased, and the other shapes are the same. Therefore, the roller bearing member 41 is moved up and down by being guided by the rib-shaped guide member 45 (only one is shown in FIG. 10) of the charging housing 37 in which the side walls 41b and 41c of the roller bearing member 41 are guided. Can do.

A slide plate 52 is disposed between the driven legs 41 d and 41 e and the charging housing 37.
Referring to FIGS. 12 and 13, the slide plate 52 has minute step surfaces 52a to 52c on the surface in contact with the driven legs 41d and 41e. In this embodiment, the step surfaces are thicker in the order of 52a <52b <52c. It is formed to become. The lengths of the stepped surfaces 52a to 52c in the longitudinal direction of the scorotron charger 30 are made to coincide with the lengths of the driven legs 41d and 41e. The surface of the slide plate 52 that contacts the charging housing 37 is a flat surface, and a knob 52d that protrudes toward the charging housing 37 is formed at the center. Long holes 48 and 49 are formed in the bottom portion 37 c of the charging housing 37 and the bottom wall 31 b of the shield case 31.

As shown in FIG. 14, the long holes 48 and 49 are long in the longitudinal direction of the scorotron charger 30, and the tip of the knob 52 d of the slide plate 52 is projected from the hole 49.
On the bottom wall 31b of the shield case 31, numbers 1 to 3 are imprinted along the longitudinal edge of the long hole 49. In this embodiment, in the state where the position of the knob 52d is at the imprint 1, The step surface 52a of the slide plate 52 is in a position where it contacts the driven legs 41d and 41e. In the state where the position of the knob 52d is at the stamp 2, the step surface 52b of the slide plate 52 is in a position in contact with the driven legs 41d and 41e, and when the position of the knob 52d is at the stamp 3, the step surface 52c of the slide plate 52 is located. Are in contact with the driven legs 41d and 41e.
Therefore, when the position of the knob 52d is at the stamp 1, the roller bearing member 41 is at the lowest position. When the knob 52d is at the stamp 2, the roller bearing member 41 is at the intermediate height position. The highest position. Thus, the height of the gap roller 40 can be adjusted by moving the roller bearing member 41 up and down.
Such slide plates 52 are disposed at both left and right ends of the scorotron charger 30, and other constituent members of the scorotron charger 30 are the same as those in the first embodiment.

When the surface potential of the scorotron charger 30 varies, the knob 52d protruding from the bottom surface of the shield case 31 is moved along the slide long hole 49 so that the slide plate 52 is moved to the bottom wall of the shield case 31. 31b can be slid, and the interval between the photosensitive drum 19 and the grid 35 can be adjusted.
That is, when the knob 52 d is moved, the side walls 41 b and 41 c of the roller bearing member 41 in contact with the slide plate 52 can be moved up and down by being guided by the rib-shaped guide member 45 of the charging housing 37. The roller bearing member 41 moves up and down depending on the height relationship between the step surfaces 52 a to 52 c of the slide plate 52. Therefore, when the stepped surface 52a and the driven legs 41d and 41e of the roller bearing member 41 are in contact with each other, the distance between the photosensitive drum 19 and the grid 35 is the smallest, and as the movement to the regions 52b and 52c sequentially, The interval becomes larger. As described above, since the gap between the grid 35 and the photosensitive drum 19 is 0.6 to 0.8 mm, the difference in the radius of curvature of the regions 52a to 52c is within that range.

When the roller bearing member 41 moves up and down by sliding the slide plate 52 as described above, the gap roller 40 is in contact with the photosensitive drum 19, so that the charging housing 37 is relative to the photosensitive drum 19. Move to. Therefore, since the grid 35 assembled to the charging housing 37 also moves relative to the photosensitive drum 19, the distance between the photosensitive drum 19 and the grid 35 can be changed. In such a scorotron charger, the distance is set. Can be uniformly charged within a certain range.
Therefore, the first embodiment is different from the first embodiment in that the distance between the photosensitive drum 19 and the grid 35 can be adjusted in four stages, while in the present embodiment, the photosensitive drum 19 and Except that the distance from the grid 35 can be adjusted, the same effects as those of the first embodiment can be obtained. However, the same effect can be obtained by forming four step surfaces on the slide plate.

Although the embodiments of the present invention have been described above, the present invention can be modified or changed based on the technical idea of the present invention.
For example, in the first embodiment, numbers corresponding to the regions 50a to 50d are given to the outer peripheral side surfaces of the height adjusting roller 46, but different colors are used for the regions 50a to 50d on the outer peripheral surface of the height adjusting roller 46. It may be applied and distinguished by color.

1 is a side view of an image forming apparatus including a scorotron charger according to a first embodiment of the present invention. It is a perspective view of the one end part of the scorotron charger of FIG. FIG. 2 is an exploded perspective view of the scorotron charger in FIG. 1. It is sectional drawing which cut | disconnected the scorotron charger of FIG. 1 in the longitudinal direction. FIG. 3 is a perspective view of a roller bearing member and a height adjustment roller of the scorotron charger in FIG. 2. It is sectional drawing of the XX direction of FIG. It is a side view of the height adjustment roller of the scorotron charger of FIG. It is the perspective view which looked at the scorotron charger of FIG. 1 from the bottom face direction. It is a perspective view which shows the engagement relationship of the roller bearing member and grid of the scorotron charger of FIG. It is a disassembled perspective view of the scorotron charger of the 2nd Embodiment of this invention. It is sectional drawing which cut | disconnected the scorotron charger of FIG. 10 to the longitudinal direction. It is sectional drawing of a part with the gap roller of the scorotron charger of FIG. It is a perspective view which shows the engagement relationship of the roller bearing member and slide board of the scorotron charger of FIG. It is the perspective view which looked at the scorotron charger of FIG. 10 from the bottom face direction. It is a perspective view of the conventional scorotron charger. 15 shows a roller bearing member of the scorotron charger shown in FIG. 15, wherein A is a front view showing a state where the gap roller is fitted in the recess fitting recess of the roller bearing, and B is a case where the gap roller is fitted in the positioning fitting recess. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 19 Photosensitive drum 30 Scorotron charger 31 Shield case 33 Corona wire 35 Grid 37 Charging housing 40 Gap roller 41 Roller bearing member 46 Height adjustment roller 52 Slide plate 52a Step surface

Claims (6)

A corona wire stretched in an electrically conductive shield case; and a grid that is spaced apart from the corona wire; and a charging housing that supports the grid is provided at an end of the shield case The charging housing accommodates a gap roller that abuts on the peripheral surface of the photosensitive member, and a rotating shaft of the gap roller is held by a bearing of a bearing member disposed in the charging housing. In the charger,
The bearing member is disposed so as to be relatively movable with respect to the charging housing, and a position adjusting member is disposed in the charging housing so that the bearing member is relatively movable with respect to the charging housing .
The position adjusting member is a disc material having a plurality of curved surfaces with different radii of curvature on an eccentric shaft or a concentric circle disposed rotatably at the bottom of the charging housing, and the outer peripheral surface of the disc material on the bearing member scorotron charger of the image forming apparatus is characterized in that so as to abut the. A hole is formed in the bottom surface of the shield case and the charging housing, and an outer peripheral portion of the disc material is disposed in the hole so as to protrude outward from the bottom surface of the shield case. 2. A scorotron charger for an image forming apparatus according to 1 . The scorotron charger for an image forming apparatus according to claim 2 , wherein a position display for identifying a size of a gap between the photosensitive member and the grid is provided on an outer peripheral portion or an outer peripheral side surface of the disc material. A corona wire stretched in an electrically conductive shield case; and a grid that is spaced apart from the corona wire; and a charging housing that supports the grid is provided at an end of the shield case The charging housing accommodates a gap roller that abuts on the peripheral surface of the photosensitive member, and a rotating shaft of the gap roller is held by a bearing of a bearing member disposed in the charging housing. In the charger,
The bearing member is disposed so as to be relatively movable with respect to the charging housing, and a position adjusting member is disposed in the charging housing so that the bearing member is relatively movable with respect to the charging housing.
The position adjusting member is a slide plate formed with a stepped surface slidably disposed at the bottom of the charging housing, wherein the stepped portion of the stepped surface is slid on the bearing member. scorotron charger of images forming apparatus you. Said slide plate to form a knob for the slide, according to claim 4, characterized in that the said knob from the shield case and the slide hole formed in the bottom surface of the charge housing so as to protrude to the outside of the shield case A scorotron charger for the image forming apparatus described in 1. 6. The scorotron charger for an image forming apparatus according to claim 5 , wherein a position indication for identifying a size of a gap between the photoconductor and the grid is provided in a slide hole on a bottom surface of the shield case.

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