JP2005055753A - Charging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging device having a cleaning unit, which is small in the number of components and restricts the size of the entire charging device approximately to the conventional size. <P>SOLUTION: The charging device 10 includes: a U-shaped cross-sectional shield plate 12 made of a thin metal plate, which is disposed on the main body 11 of the device so as to freely reciprocate in the direction of its length; a saw-teeth-like discharge plate 13 made of a thin metal plate, which is fixed in the middle of the shield plate and moves together with the shield plate 12; and cleaning rollers 14 attached to the main body 11 of the device so as not to hinder the movement of the shield plate 12 and so as to move in relation to and in contact with the discharge roller 13 when the shield plate 12 is reciprocally moved. The cleaning rollers 14 have bristles as of a brush, which freely rotate around their respective axes parallel to the discharge member 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a charging device. More particularly, the present invention relates to a charging device that charges a photosensitive drum of an image forming apparatus that employs an electrophotographic system such as a copying machine, a printer, or a facsimile.

  2. Description of the Related Art Conventionally, there has been proposed a cleaning device capable of cleaning a discharge member at an appropriate time, not limited to the replacement time of components in the image forming apparatus. For example, Patent Document 1 includes a feed screw that is arranged in parallel with a sawtooth discharge member and is driven to rotate by a motor, and a female screw that is screwed with the feed screw, and moves along the longitudinal direction so as not to rotate. A freely guided holder, a pair of left and right brush rollers supported by the holder so as to be movable up and down so as to sandwich the discharge member, and a cam for moving the brush roller up and down as the holder moves in the longitudinal direction A cleaning device for a corona charging device including a member is disclosed. In this case, when the motor is driven, the feed screw rotates and the holder moves linearly in the axial direction. As a result, the brush roller can be cleaned while sandwiching the sawtooth discharge member from the left and right while moving up and down.

On the other hand, Patent Literature 2 discloses a pair of a holding member that is provided so as to be movable in the longitudinal direction inside a shield plate that is fixed to the apparatus body, and a pair that is provided rotatably on the holding member so as to sandwich a sawtooth discharge member. And a cleaning device for a sawtooth discharge member having a cleaning brush. In this case, when the holding member is manually reciprocated along the longitudinal direction, the pair of cleaning brushes move in the longitudinal direction while being in contact with the discharge member. Thereby, the discharge member can be cleaned.
JP-A-8-190255 JP 2003-15384 A

  In the conventional cleaning device, the cleaning mechanism is automatically or manually moved along the discharge member, and the cleaning brush or the like is rotated based on the movement. Therefore, the number of parts tends to increase, and the entire charging device itself also increases. An object of the present invention is to provide a charging device including a cleaning unit that has a small number of parts and can suppress the overall size of the charging device to approximately the same level as the conventional one.

  The charging device of the present invention includes a shield plate that is reciprocally movable in the longitudinal direction with respect to the apparatus main body, a discharge member that is arranged in parallel with the shield plate, and a shield plate that does not hinder the movement of the shield plate. And a cleaning member attached to the apparatus main body or the shield plate so as to move relatively while contacting the discharge member.

In such a charging device, it is preferable that the cleaning member includes a brush-shaped or roller-shaped contact portion that is rotatable around an axis parallel to the discharge member. Furthermore, it is more preferable that the discharge member is fixed to a shield plate via an electrical insulating member, and the cleaning member is attached to the apparatus main body.
At this time, the side surface of the discharge member may be fixed to the inner surface of the side wall at the front end and the rear end of the shield plate via the electric insulating member. The side wall of the shield plate may be separated on the right and left sides, and one of the side walls may be configured to be reciprocally movable in the longitudinal direction with respect to the apparatus main body.

  In the charging device of the present invention, the shield plate is provided so as to be reciprocally movable in the longitudinal direction with respect to the apparatus main body, and by moving the shield plate, a relative movement is given to the discharge member and the cleaning member. . That is, since the shield plate is continuous with the same cross-sectional shape in the longitudinal direction, interference with other components does not occur even if it is moved in the longitudinal direction. In the present invention, in view of this point, the operation member is also used by the shield plate. As a result, the number of parts can be reduced, and the manufacturing cost can be reduced. Furthermore, the cleaning means can be incorporated without enlarging the charging device.

  In such a charging device, when the cleaning member includes a brush-shaped or roller-shaped contact portion that is rotatable around an axis parallel to the discharge member, the brush-shaped member is used when the shield plate is moved back and forth. Or a roller-shaped contact part rotates, contacting with a discharge member, and can clean a discharge member efficiently. Moreover, the lifetime of the cleaning member is prolonged.

  Furthermore, when the discharge member is fixed to the shield plate via the electrical insulating member and the cleaning member is attached to the main body of the apparatus, there is no relative movement between the discharge member and the shield plate, so the distance between the two is accurately maintained. Therefore, the designed discharge performance can be sufficiently exhibited. Further, since the cleaning member is attached to the apparatus main body, it can be stably supported even when the cleaning member is rotated.

  Next, an embodiment of a charging device according to the present invention will be described with reference to the drawings. 1 is a perspective view showing an embodiment of the charging device of the present invention, FIG. 2 is a partially cutaway front view of the charging device of FIG. 1, and FIG. 3 is a partially cutaway side view of the charging device of FIG. 4 is a perspective view showing the operating state of the apparatus shown in FIG. 1, FIG. 5 is a perspective view showing a main part of another embodiment of the charging apparatus of the present invention, FIG. 6 is a cross-sectional view of the main part of the charging apparatus, and FIG. FIG. 6 is a partially cutaway front view showing still another embodiment of the charging device of the invention.

  A charging device 10 shown in FIG. 1 includes a device main body 11, a shield plate 12 slidably attached to the device main body, and a sawtooth discharge plate 13 having front and rear ends held by the shield plate. And a pair of cleaning rollers 14 provided to be rotatable with respect to the apparatus main body. The apparatus main body 11 is a member for fixing the charging device 10 to a frame such as a copying machine, for example, has a thick plate shape, and has guide grooves 21 formed on the left and right side surfaces. The apparatus main body 11 is constituted by an inner surface of a synthetic resin having electrical insulation. As the synthetic resin, for example, ABS resin is used.

  The shield plate 12 is a long part having the same cross section formed by bending a metal plate into a U-shaped cross section, and is slidably fitted into the guide groove 21 inwardly from the upper ends of the left and right side walls 22. The mated lip 23 projects. As the material of the shield plate 12, a conventionally used material such as a stainless steel plate is adopted. The side wall 22 and the bottom wall 24 may be formed separately and connected in an electrically insulated state. In that case, a large number of slits can be formed in the bottom wall 24 and used as a grid for discharge control.

  Further, holding members 25 for holding the front and rear ends of the discharge plate 13 are provided at the front end and the rear end of the shield plate 12. The holding member 25 can be made of an electrically insulating material, for example, a synthetic resin such as ABS resin. A vertical groove 26 for holding the discharge plate 13 is formed in the holding member 25, and a screw hole (not shown) for fixing the discharge plate from the lateral direction is formed.

  The discharge plate 13 is composed of a thin metal plate having a number of sawtooth electrodes for discharge at the lower end. The discharge plate 13 can be formed, for example, by etching a stainless steel plate having a thickness of 0.1 mm. Both ends of the discharge plate 13 are formed with screw holes for fitting with the holding member 25 and fixing with screws.

  As shown in FIG. 2, the cleaning roller 14 is provided in a pair of left and right, and each cleaning roller 14 is rotatably supported at the upper end of the apparatus main body 11, and the lower end is freely rotatable by a separate suspension support 27. It is supported by. The suspension support 27 can be made of a metal plate or a synthetic resin. The cleaning roller 14 is composed of, for example, a synthetic resin roll main body 28 and a brush-like brush 29 planted on the outer periphery thereof. The brush 29 is elastically brought into contact with both surfaces of the discharge plate 13, particularly in a range including a sawtooth discharge electrode at the lower end. This is because dirt is particularly likely to occur in this portion. 2 denotes a conventionally known photosensitive drum to which a bias is applied by the charging device 10. The portion where the cleaning roller 14 is provided is near the end of the charging device 10 as shown in FIG. However, it may be provided at the center or at the left and right ends.

  The charging device 10 configured as described above applies −400 V (DC) to the side wall 22 of the shield plate 12, −5 kV (DC) to the discharge plate 13, and the bottom wall (grid) 24 of the shield plate 12. The surface potential of the photosensitive drum 30 can be controlled to about −600 V by applying −600 V (VC) to the discharge plate 13 and discharging from the serrated tip of the discharge plate 13. Thereafter, the photosensitive drum 30 is exposed to form a latent image and developed with toner supplied from a developing device. Further, after the toner is transferred by bringing the transfer paper into close contact, an image can be formed on the transfer paper by fixing with a fixing device.

  When a large number of images are formed, an oxide such as silica (SiO) adheres to the discharge plate 13 and the discharge performance deteriorates. Therefore, after canceling each applied voltage, the shield plate 12 is pulled out from the apparatus main body 11 in the direction of arrow F as shown in FIG. At that time, since both ends of the discharge plate 13 are held by the shield plate 12, the discharge plate 13 is pulled out in the direction of arrow F together with the shield plate 12. At that time, since the brush 29 of the cleaning roller 14 is in sliding contact with the surface of the discharge plate 13, the cleaning roller 14 rotates. Thereby, oxides and the like adhering to the discharge plate 13 are scraped off and cleaning is performed. Even if the cleaning roller 14 is not sufficiently rotated, the surface of the discharge plate 13 is rubbed by the brush 29, so that considerable cleaning is achieved. Next, the shield plate 12 is pushed into the original state as shown in FIG. In addition, cleaning is more reliably performed by alternately repeating the drawing and pushing several times.

  In the charging device 10, the left and right side walls 22 of the shield plate 12 are connected by the bottom wall 24. However, the left and right side walls 22a and 22b may be separated from each other as in the charging device 32 shown in FIG. In this case, one side wall 22a is slidably held with respect to the apparatus main body 2, and the other side wall 22b is fixed to the apparatus main body 11 with screws or the like. Then, both ends of the discharge plate 13 are attached to the front and rear ends of the movable side wall 22a via the holding member 25. This can also be cleaned by causing a relative movement between the cleaning roller 14 and the discharge plate 13 by reciprocally sliding the movable side wall 22a of the shield plate 12. When the grid is provided on the charging device 32 of the type in which the left and right side walls 22a and 22b are separated, the grid is made detachable and the grid is removed before the cleaning operation.

  In the case of the charging device 32 of FIG. 5, the upper end of the movable side wall 22a is set as a guide portion 22c bent in, for example, a T shape, and the guide groove 21 is a T groove that is slidably fitted to the bent portion. (See FIG. 6). Thereby, the side wall 22a can be guided so as not to fluctuate. Such a fitting and holding structure can also be employed in the shield plate 12 that connects the side walls 22a and 22b on both sides as shown in FIG.

  Further, the cleaning roller 14 in this embodiment is rotatably provided around a fixed shaft 35 suspended and held on the apparatus main body 11 by screws 33, washers 34, and the like. Thus, the cleaning roller 14 can be held in a cantilever manner. Further, the cleaning roller 14 is composed of a roll body 36 and an elastic roll 37 made of a cylindrical synthetic resin foam adhered around the main body 36 without using a brush-like brush. Instead of the rolling cleaning roller, a fibrous cleaning member such as a foam or cloth fixed to the fixed shaft 35 may be used.

  In the charging device 32 of the type in which the left and right side walls 22a and 22b of the shield plate 12 of FIGS. 5 and 6 are separated, the right side wall 22b is configured to be movable with respect to the apparatus body 11 in the same manner as the left side wall 22a. The front and rear ends of the side walls 22a and 22b can be joined together by the holding member 25 similar to the case of 1. In this case, since the shield plate composed of the left and right side walls can be operated integrally, the shield plate 12 to which the grid is attached can be pulled out or pushed in from the apparatus main body 11.

  In any of the above-described charging devices, the cleaning member is attached to the apparatus main body. However, the cleaning member 39 can be attached to the shield plate 12 as in the charging device 38 shown in FIG. In that case, the discharge plate 13 is fixed to the apparatus main body 11, and relative movement occurs between the discharge plate 13 and the cleaning member 39 when the shield plate 12 is pulled out. The cleaning member 39 may be formed by, for example, fixing the suspension member 40 to the inner surface of the side wall 22 of the shield plate 12 and supporting the cleaning member 39 on the suspension member 40. The cleaning member 39 may be in a roll shape that abuts on the discharge plate 13 and rolls, or may simply be in sliding contact. However, in the case of a sawtooth discharge plate, there is an advantage that rolling is less likely to damage the cleaning member. The cleaning member 39 is provided near the end of the shield plate 12 on the side opposite to the side from which the shield plate 12 is drawn.

  In the charging device 38 of the type in which the cleaning member 39 is attached to the shield plate 12 as shown in FIG. 7, the left and right side walls 22 and 22 are integrated via the bottom wall 24 and moved together. In FIG. 7, the upper edge of the discharge plate 13 is inserted into a slit formed on the lower surface of the apparatus main body 11, but a holding member substantially the same as the holding member 25 of FIG. 1 is directed downward from the front end and rear end of the apparatus main body 11. The both ends of the discharge plate 13 may be held by them. This is easier to hold in a state where the discharge plate 13 is stretched.

  In any of the above-described embodiments, the discharge plate is employed as the discharge member, but other discharge members such as a discharge wire may be employed. In such a case, the discharge wire or the like can be efficiently cleaned with a simple configuration. The discharge wire is less likely to get dirty than a discharge plate having a sawtooth discharge electrode, and is easy to clean. Therefore, it is sufficient to employ a cleaning member that is simply slidably contacted instead of a roller-shaped cleaning member. Moreover, in the said embodiment, although the shield board 12 is taken in / out by hand, you may make it take in / out and position by motor drive.

1 is a perspective view showing an embodiment of a charging device of the present invention. FIG. 2 is a partially cutaway front view of the charging device of FIG. 1. FIG. 2 is a partially cutaway side view of the charging device of FIG. 1. It is a perspective view which shows the operating state of the apparatus of FIG. It is a principal part perspective view which shows other embodiment of the charging device concerning this invention. FIG. 6 is a cross-sectional view of a main part of the charging device in FIG. 5. FIG. 6 is a partially cutaway front view showing still another embodiment of the charging device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Charging device 11 Device main body 12 Shield plate 13 Discharge plate 14 Cleaning roller 21 Guide groove 30 Photosensitive drum 32 Charging device 39 Cleaning member

Claims (5)

A shield plate provided to be freely reciprocable in the longitudinal direction with respect to the apparatus main body;
A discharge member arranged in parallel with the shield plate;
A charging device comprising: a cleaning member attached to the apparatus main body or the shield plate so as to move relatively while contacting the discharge member when the shield plate is reciprocated.   The charging device according to claim 1, wherein the cleaning member includes a brush-shaped or roller-shaped contact portion that is rotatable about an axis parallel to the discharge member.   The charging device according to claim 1, wherein the discharge member is fixed to a shield plate via an electric insulating member, and the cleaning member is attached to the apparatus main body.   The charging device according to claim 1, wherein a side surface of the discharge member is fixed to an inner surface of a side wall at a front end and a rear end of the shield plate via an electric insulating member. The charging device according to claim 4, wherein the side wall of the shield plate is separated on the right and left sides, and one side is reciprocally movable in the longitudinal direction with respect to the apparatus main body.

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