JP5256242B2 - Charging device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic method, and more particularly to a charging device that charges a photoreceptor.

  In the electrophotographic image forming apparatus, the scorotron method has been mainly used as a charging method for a photoreceptor for forming an electrostatic latent image. However, in recent years, the amount of generated ozone is small due to a safety problem with respect to the generation of ozone. Many contact charging roller systems are employed.

  When such a contact-type charging device is used, if the surface of the photosensitive drum is contaminated with foreign matters such as toner components or transfer paper paper dust, these foreign matters cause an increase in the surface resistance of the charging roller, As a result of the decrease in charging performance, the image quality decreases. In addition, partial contamination on the surface of the charging roller is likely to appear as a defect such as density unevenness (black stripes) in a gray image, which is a main factor that governs the life of the charging roller.

  In order to avoid these problems, for example, in Patent Document 1, a brush roller for cleaning the surface of the charging roller is provided, and by rotating the brush roller in the longitudinal direction at the same time, a partial surface of the surface of the charging roller is obtained. A method for reducing significant contamination is disclosed. The configuration around the brush roller as shown in Patent Document 1 is shown in FIG.

  As shown in FIG. 18, a brush roller 33 that cleans the surface of the charging roller 31 is provided in the housing 3 a of the charging device 3, and the tip of the brush that is generated when the brush roller 33 rotates is bent back. The foreign material on the surface of the charging roller 31 is repelled by the elastic force. However, in recent years, there has been an increasing demand for cost reduction and downsizing of the apparatus body, and it has been proposed to use a plate-like brush that is more compact than a brush roller.

  Further, for example, Patent Document 2 discloses a method of preventing contamination of the charging roller due to a foreign matter scraping through a cleaning blade by thrust-moving a plate-like brush with respect to the charging roller. A configuration around the plate-like brush as shown in Patent Document 2 is shown in FIG.

  As shown in FIG. 19, a plate-like brush 35 for cleaning the surface of the charging roller 31 is provided in the housing 3 a of the charging device 3. The plate-like brush 35 includes a support plate 35a and a brush portion 35b protruding from the support plate 35a toward the photosensitive drum 2 and moves in a thrust direction perpendicular to the paper surface of the drawing.

JP 2007-155844 A JP 2006-195154 A

  Here, FIG. 20 shows a contact state between the plate-like brush and the charging roller from the direction A in FIG. The brush portion 35b bends in accordance with the curvature of the charging roller 31, and as shown in FIG. 20, the charging roller particularly in the center portion in the short side direction (vertical direction with respect to the drawing sheet, see the left-right direction in FIG. 19). Since the distance between 31 and the support plate 35a is short, the curvature of the brush portion 35b is large. Further, even if the brush member 35 undergoes thrust movement, the distance between the support plate 35 a and the charging roller 31 does not change in the contact area between the brush portion 35 b and the charging roller 31.

  For this reason, at the central portion in the short direction of the brush portion 35b, even if the plate-like brush 35 thrusts in the longitudinal direction (left-right direction in the figure), the tip of the brush portion 35b may hardly move in the thrust direction. As a result, the sliding distance with respect to the charging roller 31 is shortened at the central portion in the short direction, and it becomes difficult to sufficiently exhibit the cleaning ability of the charging roller 31.

  As described above, with the brush roller as disclosed in Patent Document 1, the cost increases and it is difficult to reduce the size of the apparatus main body. Further, the cost of the plate-like brush as in Patent Document 2 is low, but even if the plate-like brush is simply reciprocated in the longitudinal direction (thrust direction), the sliding distance of the charging roller surface by the brush portion is short. It is difficult to demonstrate sufficient cleaning ability. Further, it is difficult to sufficiently clean the foreign matter attached to the surface of the charging roller intensively along the thrust direction by simply moving the plate brush in the thrust direction.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a charging device that exhibits a high cleaning ability for a charging member, and that can be reduced in size at low cost, and an image forming apparatus including the charging device. Objective.

  In order to achieve the above object, the present invention provides a contact-type charging member that is charged while rotating in contact with an image carrier, a brush member that can contact the charging member and rub the surface of the charging member, The brush member is provided with a plate-like support portion and a brush portion protruding from the support portion and in contact with the charging member, and the brush member includes the brush portion And the charging member reciprocate along the axial direction of the charging member, and reciprocate along the direction perpendicular to the axial direction.

  The brush member may reciprocate substantially linearly along the vertical direction.

  In the invention, it is preferable that the brush member reciprocates substantially linearly in a direction orthogonal to the axial direction of the charging member and along a tangential direction with respect to the peripheral surface of the charging member. It is said.

  According to the present invention, the brush member is swingable about the axial direction, and reciprocates in a substantially arc shape along the vertical direction.

  Further, the present invention is characterized in that the brush member reciprocates in a direction perpendicular to the axial direction of the charging member and along a normal direction with respect to the peripheral surface of the charging member.

  Further, the present invention is characterized in that the brush portion is formed on the support portion by electrostatic flocking and has a plurality of gaps inclined with respect to the vertical direction.

  The present invention also provides an image forming apparatus including the charging device.

  According to the first configuration of the present invention, the brush member is provided with the plate-like support portion and the brush portion that protrudes from the support portion and contacts the charging member, and the brush member includes the brush portion and the charging member. The reciprocating motion along the axial direction of the charging member at the contact portion and the reciprocating motion along the direction perpendicular to the axial direction can increase the rubbing distance of the tip of the brush portion with respect to the charging member surface. Therefore, the charging member can exhibit high cleaning ability and can be downsized at low cost.

  According to the second configuration of the present invention, in the charging device of the first configuration, the brush member reciprocates substantially linearly along the vertical direction, so that the charging member has a simpler configuration. High cleaning ability can be demonstrated.

  According to the third configuration of the present invention, in the charging device having the first configuration, the direction is perpendicular to the axial direction of the charging member and the direction tangential to the circumferential surface of the charging member. By reciprocating substantially linearly, a high cleaning ability can be exhibited with respect to the charging member with a simpler configuration.

  According to the fourth configuration of the present invention, in the charging device having the first configuration, the brush member can swing around the axial direction and reciprocates in a substantially arc shape along the vertical direction. By this, since the elastic force of a brush part can be exhibited more, a higher cleaning capability can be exhibited with respect to a charging member.

  According to the fifth configuration of the present invention, in the charging device of the first configuration, the brush member is in a direction orthogonal to the axial direction of the charging member and with respect to the peripheral surface of the charging member. By reciprocating along the normal direction, the elastic force of the brush part can be exhibited more, so that a higher cleaning ability can be exhibited for the charging member.

  According to the sixth configuration of the present invention, in the charging device having any one of the first to third configurations, the brush portion is formed on the support portion by an electrostatic flocking method, and in the vertical direction. By adopting a configuration having a plurality of gaps inclined relative to each other, it is possible to prevent interference between the brush portions and to clean the charging member more uniformly.

  Further, according to the seventh configuration of the present invention, the image forming apparatus including the charging device having any one of the first to sixth configurations prevents the deterioration of the image quality due to the decrease in the charging performance. can do.

1 is a schematic cross-sectional view illustrating an image forming apparatus including a charging device according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a configuration around a charging device according to a first embodiment of the present invention. FIG. 2 is a schematic enlarged sectional view showing the periphery of the plate-like brush and the charging roller of FIG. Schematic showing the brush part of a plate-like brush Schematic enlarged sectional view showing a state where the plate-like brush is pressed against the surface of the charging roller Schematic side view showing the configuration around the plate-like brush from the direction B in FIG. FIG. 3 is a schematic view showing a state in which the plate-like brush has moved to one side in the longitudinal direction and the lateral direction from the direction C in FIG. FIG. 3 is a schematic view showing a state in which the plate-like brush has moved to the other in the longitudinal direction and the transverse direction from the direction C in FIG. Schematic showing the state of movement of the plate brush in the short direction Schematic showing the moving state of the plate-like brush from below in FIG. DD 'sectional view of FIG. The schematic side view which shows the structure of the plate-shaped brush periphery used for the charging device which concerns on 2nd Embodiment of this invention. FIG. 12 is a schematic view showing the state in which the plate-like brush has moved to one side in the longitudinal direction and the lateral direction from above. Schematic diagram showing the state in which the plate-like brush has moved to the other in the longitudinal direction and the lateral direction from above in FIG. EE 'sectional view of FIG. Schematic diagram showing the swinging state of the plate-like brush in the short direction from the left side of FIG. Schematic which shows the movement state of a plate-shaped brush from the lower part of FIG. Schematic cross-sectional view showing the periphery of a brush roller used in a conventional charging device Schematic sectional view showing the periphery of a plate-shaped brush used in a conventional charging device The figure which shows the contact state of a plate-shaped brush and a charging roller from the A direction of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an image forming apparatus including a charging device according to an embodiment of the present invention. An image forming unit P is disposed in the image forming apparatus 1. The image forming unit P forms a predetermined image through each process of charging, exposure, development, and transfer.

  In this image forming portion P, a photosensitive drum (image carrier) 2 that carries a visible image (toner image) is disposed, and the toner image formed on the photosensitive drum 2 is a sheet (recording). The image is transferred onto a medium 6 and further fixed on the sheet 6 in the fixing unit 7 and then discharged from the apparatus main body. An image forming process for the photosensitive drum 2 is executed while rotating the photosensitive drum 2 clockwise in FIG. 1 by a drive motor (not shown).

  Next, the image forming unit P will be described in detail. Around and around the photosensitive drum 2 rotatably disposed, a charging device 3 for charging the photosensitive drum 2, an exposure unit 4 for exposing image information to the photosensitive drum 2, and the photosensitive drum 2 A developing unit 5 that forms a toner image thereon, a cleaning device 9 that collects the developer (toner) remaining on the photosensitive drum 2, and a static eliminator 10 that removes the electrostatic latent image are provided. .

  First, the surface of the photosensitive drum 2 is uniformly charged by the charging roller 31 provided in the charging device 3, and then the light is irradiated by the exposure unit 4, and the electrostatic latent image corresponding to the image signal on the photosensitive drum 2. Form. The developing unit 5 includes a developing roller 5 a disposed so as to face the photosensitive drum 2, and the developing unit 5 is filled with a predetermined amount of a magnetically charged positive component toner by a toner container 11. The toner is supplied to the surface of the photosensitive drum 2 by a developing roller 5a to which a developing bias is applied by a developing bias applying device (not shown), and is formed by exposure from the exposure unit 4 by electrostatic adhesion. A toner image corresponding to the electrostatic latent image is formed. The details of the charging device 3 will be described later.

  The sheet 6 on which the toner image is transferred is accommodated in a paper feed cassette 12 that accommodates the sheet 6, and is directed toward the photosensitive drum 2 on which the toner image is formed via the paper feed roller 13 and the registration roller 14. Be transported. At this time, the image writing signal is turned on, and the image is formed on the photosensitive drum 2 so that the toner image is transferred to a predetermined position on the sheet 6. A toner image on the photosensitive drum 2 is transferred onto the sheet 6 by applying an electric field to the lower portion of the photosensitive drum 2 with a transfer roller 17 to which a predetermined transfer bias is applied.

  The sheet 6 on which the toner image is transferred is conveyed to the fixing unit 7. In addition, the photosensitive drum 2 after the toner image is transferred is collected by the cleaning device 9 in preparation for the subsequent formation of a new electrostatic latent image. The sheet 6 conveyed to the fixing unit 7 is heated and pressed by the fixing roller 7a, and the toner image is fixed on the surface of the sheet 6 to form a predetermined image. The sheet 6 on which the image is formed is then discharged to a discharge tray 19 by a discharge roller 18.

  2 is a schematic cross-sectional view showing the configuration around the charging device according to the first embodiment of the present invention, and FIG. 3 is a schematic enlarged cross-sectional view showing the periphery of the plate-like brush and the charging roller in FIG. 4 is a schematic view showing a brush portion of the plate-like brush, and FIG. 5 is a schematic enlarged sectional view showing a state where the plate-like brush is pressed against the surface of the charging roller. Portions common to those in FIG. 1 are denoted by common reference numerals and description thereof is omitted. In FIG. 2, the arrow direction passing between the photosensitive drum 2 and the transfer roller 17 indicates the conveyance direction of the sheet 6, and in FIG. 5, the support plate 35a is indicated by a broken line.

  As the photosensitive drum 2, for example, an amorphous silicon (a-Si) drum can be used, and the photosensitive drum 2 is rotated clockwise in the drawing as described above.

The charging device 3 is provided with a charging roller 31 that rotatably contacts the surface of the photosensitive drum 2 and charges the drum surface. The charging roller 31 is, for example, a rubber layer (eg, epichlorohydrin rubber having a resistance value of 10 ⁵ to 10 ⁶ Ω and a surface roughness R _Z = 10 μm on the peripheral surface of a metal shaft (core metal) 31a (see FIG. 6). A solid type such as a conductive rubber roller on which an elastic layer is formed can be suitably used.

  In addition, the rubber layer can be formed from an electron conductive material in which carbon is dispersed in epichlorohydrin rubber or an ion conductive material in which an ionic conductive material is added to epichlorohydrin rubber. It is not limited to. In addition, for example, a sponge type in which a foam rubber roller is covered with a tube can be used.

  The charging roller 31 is rotatably supported by the housing 3 a of the charging device 3. Further, the charging roller 31 is pressed against the photosensitive drum 2 with a predetermined nip pressure, and is rotated by being driven by the photosensitive drum 2. In addition, a charging bias having the same polarity as the toner (here, positive polarity) is applied to the charging roller 31 during image formation.

  Specifically, the cored bar 31a (see FIG. 6) of the charging roller 31 is electrically connected to a power source (not shown), and a charging bias composed of a DC voltage in which an AC voltage is superimposed on the charging roller 31 by the power source. Is applied. By applying such a charging bias, the surface of the photosensitive drum 2 can be charged by a current that flows according to the resistance of the rubber layer of the charging roller 31. Note that a DC voltage can also be applied to the charging roller 31.

  Further, a transfer bias having a polarity opposite to that of the toner is applied to the transfer roller 17 during image formation.

  The cleaning device 9 includes a cleaning blade 22 for removing residual toner on the surface of the photosensitive drum 2 and a cleaning roller for removing residual toner on the surface of the photosensitive drum 2 and rubbing and polishing the surface of the photosensitive drum 2. 23, a recovery spiral 24 as a toner discharging means, and a scraper 25 are provided. The cleaning blade 22 is in contact with the surface of the photosensitive drum 2 so as to serve as a counter with respect to the rotation direction of the drum (clockwise in FIG. 2).

  The cleaning blade 22 is formed of a plate-like urethane rubber having a hardness of 70 °, a free length of 10 mm, and a thickness of 2.2 mm, and is set so that the amount of biting into the photosensitive drum 2 is 1.2 mm. The material, shape, amount of biting, and the like of the cleaning blade 22 can be set as appropriate according to the apparatus configuration.

  The cleaning roller 23 is formed of a foamed material made of EPDM rubber having a wall thickness of 2 mm and an outer diameter of 14 mm, and in the nip portion with the photosensitive drum 2 in the same direction as the photosensitive drum 2 (counterclockwise in FIG. 2). The photosensitive drum 2 is rotated at a peripheral speed of 1.2 times.

  A scraper 25 protruding from the support portion 26 is disposed downstream of the nip portion between the cleaning roller 23 and the photosensitive drum 2 with respect to the rotation direction of the cleaning roller 23. The scraper 25 is formed of a SUS plate having a thickness of 80 μm, and a free end is in contact with the surface of the cleaning roller 23. The scraper 25 can scrape off the development residual toner adhering to the surface of the cleaning roller 23 due to the nip pressure between the cleaning roller 23 and the photosensitive drum 2.

  Residual toner and external additives on the surface of the photosensitive drum 2 are collected by the cleaning blade 22, the cleaning roller 23 and the scraper 25, and are collected by the rotational force of the photosensitive drum 2 and the rotational force and rotational driving of the cleaning roller 25. It is conveyed to 24. Thereafter, residual toner and the like are conveyed to a collection tank disposed outside the cleaning device 9 by the collection spiral 24 and accumulated therein. Although not shown, the cleaning device 9 is also provided with a urethane seal for preventing the toner collected in the cleaning device 9 from leaking to the outside.

  In FIG. 3, a plate-like brush (brush member) 35 is disposed above the charging roller 31 (to the right of the charging roller 31 in FIG. 2) and presses against the surface of the charging roller 31 to clean the roller surface. The plate-like brush 35 is formed of, for example, a support plate (support portion) 35a made of an elongated flat rectangle, and a brush portion 35b protruding from the support plate 35a.

  The support plate 35a is supported by the housing 3a so as to be movable in the longitudinal direction (axial direction) and the lateral direction (perpendicular to the axial direction). Moreover, the brush part 35b consists of an electroconductive brush, and this electroconductive brush is formed by flocking to the support plate 35a using an electrostatic flocking method. Moreover, the brush part 35b is formed in the flat rectangular shape along the support plate 35a as a whole.

  As the material of the brush portion 35b, for example, a conductive resin material such as nylon or polyester can be used. In addition, conductivity is imparted by combining the resin material with another conductive material. Such materials can also be used. Further, considering the cleanability of the surface of the charging roller 31, the brush length of the brush portion 35b is preferably 1 mm to 5 mm, more preferably 2 mm, and the brush wire diameter is preferably 1 denier to 10 denier, for example. Denier is more preferred.

  As shown in FIG. 4, the brush portion 35b is formed to have a plurality of slits 35ba (gap) inclined with respect to the short direction. The slits 35ba are formed with a constant width at a constant interval. By providing the slit 35ba, it is possible to prevent the foreign matter scraped from the surface of the charging roller 31 from staying between the high-density brush portions 35b formed by the electrostatic flocking method. Further, when the brush portion 35b rubs the surface of the charging roller 31, the brush portions 35b can be prevented from interfering with each other, so that the elastic force of the brush portion 35b can be more effectively exhibited.

  Further, as shown in FIG. 5, out of the region in contact with the surface of the charging roller 31 in the brush portion 35 b, the bite is the smallest at both ends in the short side direction (left and right direction in FIG. 5), and the bite at the center is the smallest. Is getting bigger. The difference d (ie, the closest distance between the surface of the charging roller 31 and the support plate 35a) between the both end portions and the central portion is preferably 0.2 mm or less and 3 mm or less, and here, 0.5 mm. It is set to be.

  6 is a schematic side view showing the configuration around the plate-shaped brush from the direction B in FIG. 3, and FIG. 7 shows the state in which the plate-shaped brush has moved to one side in the longitudinal direction and the short-side direction. FIG. 8 is a schematic view showing a state of moving to the other side from the direction C of FIG. 3, and FIG. 9 is a schematic view showing a moving state of the plate brush in the short direction, FIG. 10 is a schematic view showing the moving state of the plate-like brush from the lower side of FIG. 5, and FIG. 11 is a cross-sectional view taken along DD ′ of FIG. Portions common to FIGS. 2 to 5 are denoted by common reference numerals, and description thereof is omitted.

  As shown in FIG. 6, one end of a coil spring 34 is connected to the right end portion along the longitudinal direction (left-right direction in the drawing) of the support plate 35 a of the plate-like brush 35. The other end of the coil spring 34 is fixed to the housing 3a (see FIG. 2). As a result, the coil spring 34 biases the plate-like brush 35 to the left side in the figure.

  On the other hand, a support shaft 35c is projected on the left side along the longitudinal direction from the central portion in the short side direction (perpendicular to the paper surface of the drawing) at the left end of the plate-like brush 35. A protrusion 35d protruding downward is formed.

  On the left side of the plate-like brush 35, there is arranged a rotating member 37 having a substantially disk shape and having a shape in which the right side surface of the drawing is inclined. The rotating member 37 is rotatably supported by the housing 3a (see FIG. 2) of the charging device 3, and is connected to a driving motor (not shown) for rotating the photosensitive drum 2 via a gear (not shown). Has been. As a result, the rotating member 37 rotates as the photosensitive drum 2 rotates.

  When the rotating member 37 rotates and the tip of the support shaft 35c comes into contact with the thinnest portion of the rotating member 37 as shown in FIG. 7, the plate-like brush 35 moves to the left by the urging force of the coil spring 34, and FIG. As shown in FIG. 2, when the abutting portion is in contact with the thickest portion, the plate-like brush 35 is pressed by the thick portion and moves to the right against the urging force of the coil spring 34. That is, it reciprocates along the longitudinal direction at the contact portion between the brush portion 35b of the plate-like brush 35 and the charging roller 31 (thrust movement).

  Further, as shown in FIG. 6, a substantially linear first guide groove 39 is formed below the support shaft 35c in FIG. As shown in FIGS. 7 and 8, the first guide groove 39 is disposed to be inclined with respect to the longitudinal direction of the plate-like brush 35. A protrusion 35 d formed on the support shaft 35 c is engaged with the first groove 39 a of the first guide groove 39. The first guide groove 39 is formed in such a size and positional relationship that the projection 35d is guided along the first groove 39a.

  Accordingly, as shown in FIG. 7, when the plate-like brush 35 moves to the left side, the protrusion 35d moves downward along the first groove 39a, and moves to the right side as shown in FIG. At this time, the protrusion 35d moves upward in the drawing along the first groove 39a. That is, as shown in FIG. 9, the plate-like brush 35 reciprocates substantially linearly along the short direction (left-right direction in the figure) at the contact portion between the brush portion 35b and the charging roller 31, that is, the charging roller. It reciprocates substantially linearly along the tangential direction with respect to the circumferential surface of the charging roller 31 in a direction orthogonal to the axial direction of the charging roller 31.

  As described above, when the rotating member 37 rotates with the rotation of the photosensitive drum 2, the plate-like brush 35 moves in the longitudinal direction and the lateral direction with respect to the charging roller 31 that rotates following the photosensitive drum 2. As shown in FIG. 10, the plate-like brush 35 reciprocates in the direction (oblique direction) inclined with respect to the longitudinal direction as a whole.

  Accordingly, as shown in FIG. 11, even if a part of the brush portion 35b is disposed in the region R (see FIG. 9) where the distance from the surface of the charging roller 31 is the smallest (shown by a solid line in FIG. 11), the plate As the brush 35 moves in the short direction, the part moves to the outside of the region R (the right side or the left side in FIG. 9) (indicated by a broken line in FIG. 11).

  During such movement, the bending of the brush portion 35b is released, so that the tip of the brush portion 35b can repel the foreign matter on the surface of the charging roller 31 by the elastic force. Further, as the plate-like brush 35 reciprocates in the oblique direction, the operation of flipping out such foreign matters is sequentially performed, so that the rubbing time on the surface of the charging roller 31 becomes longer than that in the case of merely thrust movement.

  Note that the movement distance (amplitude) from the leftmost side shown in FIG. 7 to the rightmost side shown in FIG. 8 in the longitudinal thrust movement of the plate-like brush 35 is appropriately set according to the cleaning state of the charging roller 31 and the like. Although not particularly limited, for example, the thickness is preferably 1 mm or more, whereby the charging roller 31 can be sufficiently cleaned.

  On the other hand, it is preferable to set the amplitude to 3 mm or less, for example, and it is possible to avoid an unnecessary increase in size of the apparatus. In consideration of these, it is more preferable that the amplitude in the longitudinal direction is, for example, 2 mm. Further, the thrust moving period is preferably not less than one reciprocation when the charging roller 31 rotates once, but is not particularly limited.

  Further, the movement distance (amplitude) from the lowermost side shown in FIG. 7 to the uppermost side shown in FIG. 8 in the movement of the plate-like brush 35 in the short direction is appropriately set according to the cleaning state of the charging roller 31 and the like. Although not particularly limited, for example, the thickness is preferably 1 mm or more, so that the charging roller 31 can be sufficiently cleaned.

  On the other hand, it is preferable to set the amplitude to 3 mm or less, for example, and it is possible to avoid an unnecessary increase in size of the apparatus. In consideration of these, it is more preferable to set the amplitude in the short direction to 2 mm, for example. Further, the moving cycle in the short direction is preferably not less than one, although it is preferable to make one or more reciprocations when the charging roller 31 rotates once.

  As described above, the plate-like brush 35 is provided with the support plate 35a and the brush portion 35b protruding from the support plate 35a and in contact with the charging roller 31. The plate-like brush 35 is provided with the brush portion 35b and the charging roller 31. And the reciprocating motion in the axial direction (longitudinal direction) of the charging roller 31 and the reciprocating motion in the direction perpendicular to the axial direction (short direction). The sliding distance can be increased. Thereby, a high cleaning ability can be exhibited with respect to the charging roller 31. Further, since the plate-like brush 35 can be used, it is possible to reduce the size at a low cost.

  Moreover, in this embodiment, since the brush part 35b was formed in the support plate 35a by the electrostatic flocking method, and had several slit 35ba inclined with respect to the transversal direction, interference between brush parts 35b is carried out. And the charging roller 31 can be more uniformly cleaned.

  The interval between the slits 35ba and the width of the brush portion 35b separated by the slits 35ba are not particularly limited, but are shorter than the amplitude of the plate-like brush 35 and while the plate-like brush 35 reciprocates once. It is preferable to set appropriately so that the entire area of the surface of the charging roller 31 passing through the brush portion 35b contacts the brush portion 35b. Considering this viewpoint, for example, when the amount of biting of the brush portion 35b with respect to the surface of the charging roller 31 is 0.5 mm, the interval between the slits 35ba and the width of the brush portion 35b can be set to 2 mm.

  In addition, the inclination angle of the slit 35ba with respect to the short direction can be set to 30 °, for example, but the angle is not particularly limited, and the brush portions 35b interfere with each other depending on the bending state of the brush portion 35b. It can set suitably so that it may not. Moreover, it can also be set as the structure which does not provide this slit 35ba. Moreover, the formation method of the brush part 35b is not specifically limited to the electrostatic flocking method, In addition, for example, the brush part 35b can also be formed using a woven type brush.

  Further, the arrangement of the tips of the brush portions 35b in the short direction and the long direction of the plate-like brush 35, that is, the cross section viewed in the long direction and the short direction is not particularly limited to flat, and the charging roller 31 of the brush portion 35b. In addition, it can also be made into convex shape or concave shape according to the cleaning state with respect to. Further, when these are convex or concave, the curvature may be set as appropriate according to the cleaning state of the charging roller 31 and the like.

  Further, instead of making the brush portion 35b convex or concave as described above, the support plate 35a can be convex or concave. Further, the support plate 35 a can be formed from a flexible material, and the support plate 35 a can be bent according to the surface curvature of the charging roller 31.

  Further, the closest distance (difference d) between the support plate 35a and the surface of the charging roller 31 depends on the brush length of the brush portion 35b, the amplitude of the plate-like brush 35, the amount of biting of the brush portion 35b into the charging roller 31, and the like. Accordingly, it can be set as appropriate, and is not particularly limited.

  In the present embodiment, since the plate-like brush 35 reciprocates substantially linearly in the short direction, a high cleaning ability can be exhibited with respect to the charging roller 31 with a simpler configuration. However, the reciprocating movement of the plate-like brush 35 in the short direction at the contact portion between the brush portion 35b and the charging roller 31 is not particularly limited to the above embodiment.

  FIG. 12 is a schematic side view showing a configuration around a plate-like brush used in the charging device according to the second embodiment of the present invention, and FIG. 13 shows the plate-like brush moving in one direction in the longitudinal direction and the short-side direction. FIG. 14 is a schematic view showing the state moved from the top of FIG. 12, FIG. 14 is a schematic view showing the state moved to the other from the top of FIG. 12, and FIG. 15 is a cross-sectional view taken along the line EE ′ of FIG. 16 is a schematic view showing the swinging state of the plate brush in the short direction from the left side of FIG. 12, and FIG. 17 is a schematic view showing the moving state of the plate brush from the lower side of FIG. Portions common to FIGS. 2 to 11 are denoted by common reference numerals and description thereof is omitted.

  In the present embodiment, the plate-like brush 35 is thrust-moved and swung around the longitudinal direction. As shown in FIG. 12, in this embodiment, the support shaft 35c is supported so as to be movable and rotatable in the thrust direction, and the support plate 35a is movable as a whole in the thrust direction and is rotatable about the support shaft 35c. It was decided to be supported by.

  In addition, an arm portion 35e protrudes from the support shaft 35c instead of the projection portion 35d of the first embodiment, and a second guide groove portion 41 that guides the arm portion 35e is provided instead of the first guide groove portion 39. . Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  As shown in FIGS. 12-14, the 2nd guide groove part 41 is inclined and provided with respect to the transversal direction (a perpendicular direction with respect to the paper surface of FIG. 12, the up-down direction of FIG. 13 and FIG. 14). Further, as shown in FIG. 15, the second guide groove portion 41 is formed in a curved arc shape so as to protrude downward in the figure, and the arm portion 35 e is formed in the second groove 41 a of the second guide groove portion 41. Is engaged. The second guide groove 41 is formed in such a size and positional relationship that the arm 35e is guided along the second groove 41a.

  As a result, as shown in FIG. 13, when the plate-like brush 35 moves to the left side by the rotation of the rotating member 37, the support shaft 35c moves to the left side in the figure, and the tip of the arm portion 35e becomes the second groove 41a. It is guided and moves downward in the figure. As a result, the arm portion 35e and the support shaft 35c rotate counterclockwise in FIG. 15 (see the solid line in FIG. 15 and the solid line in FIG. 16).

  On the other hand, as shown in FIG. 14, when the plate-like brush 35 moves to the right side, the support shaft 35c moves to the right side in the figure, and the tip of the arm portion 35e is guided to the second groove 41a. Move up. Thereby, the arm part 35e and the support shaft 35c rotate clockwise in FIG. 15 (see the broken line in FIG. 15 and the broken line in FIG. 16). Therefore, as shown in FIG. 16, the plate-like brush 35 reciprocates in a substantially arc shape along the short direction (left-right direction in the figure) at the contact portion between the brush portion 35b and the charging roller 31, that is, the charging roller. It reciprocates in the direction orthogonal to the axial direction of 31 and along the normal direction with respect to the peripheral surface of the charging roller 31.

  As a result, as shown in FIG. 16, even when a part of the brush portion 35b is arranged in the region R where the distance from the surface of the charging roller 31 is the smallest, the plate-like brush 35 moves in the short direction, The part moves outside the region R and moves away from the charging roller 31 upward in the drawing.

  As described above, when the rotating member 37 rotates with the rotation of the photosensitive drum 2, the plate-like brush 35 moves in the longitudinal direction and swings in the short direction with respect to the charging roller 31 that rotates following the photosensitive drum 2. Therefore, as shown in FIG. 17, the plate-like brush 35 reciprocates in a direction (oblique direction) inclined as a whole with respect to the longitudinal direction.

  During such movement, the bending of the brush portion 35b is released, so that the tip of the brush portion 35b can repel the foreign matter on the surface of the charging roller 31 by the elastic force. Further, as the plate-like brush 35 reciprocates in the oblique direction, the operation of flipping out such foreign matters is sequentially performed, so that the rubbing time on the surface of the charging roller 31 becomes longer than that in the case of merely thrust movement. Further, the oscillation cycle of the plate brush 35 is preferably not less than one reciprocation while the charging roller 31 rotates once, but is not particularly limited.

  According to the present embodiment, the plate-like brush 35 can swing around the support shaft 35c (longitudinal direction), and can reciprocate in a substantially arc shape in the short side direction, so that the elastic force of the brush portion 35b can be exhibited more. Therefore, a higher cleaning ability can be exhibited with respect to the charging roller 31. The swing angle of the plate-like brush 35 can be set as appropriate according to the brush length of the brush portion 35b, and is not particularly limited.

  For example, from the viewpoint of effectively using the rubbing region by the brush portion 35b, the swing angle is such that the brush portion 35b extends from one end to the other end of the charging roller 31 while the brush member 35 reciprocates once. It is preferable that the angle is such that the contact can be made. Further, the projecting portion 35d of the first embodiment can be used as the arm portion 35e of the present embodiment.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, as the method of moving the plate-like brush 35 in the short direction, the projection 35d and the first guide groove 39, and the arm 35e and the second guide groove 41 are used. The support shaft 35c can be swung around the longitudinal direction by reciprocating in the short direction by ON / OFF of a solenoid or by connecting the support shaft 35c to a motor or the like that can rotate forward and backward. Further, the thrust moving method of the plate-like brush 35 is not particularly limited to the above embodiment.

  The image forming apparatus to which the present invention can be applied can be applied to various image forming apparatuses such as a digital copying machine, an analog copying machine, and a laser beam printer, regardless of whether it is for color or monochrome.

  The present invention provides a brush member with a plate-like support portion and a brush portion protruding from the support portion and contacting the charging member, and the brush member is charged at the contact portion between the brush portion and the charging member. And reciprocating along the axial direction, and reciprocating along the vertical direction.

  As a result, the charging member exhibits a high cleaning ability and can be reduced in size at a low cost. Therefore, it is possible to prevent the occurrence of charging failure and to extend the life of the charging device. Further, by using the image forming apparatus provided with the above charging device, it is possible to prevent a decrease in image quality due to a decrease in charging performance.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photosensitive drum (image carrier)
3 Charging device 31 Charging roller (charging member)
34 Coil spring 35 Plate brush (brush member)
35a Support plate (support part)
35b Brush part 35ba Slit (gap)
35c Support shaft 35d Projection 35e Arm 37 Rotating member 39 First guide groove 39a First groove 41 Second guide groove 41a Second groove

Claims (7)

A contact-type charging member that charges while rotating in contact with the image carrier;
A charging device having a brush member capable of sliding on the surface of the charging member in contact with the charging member,
The brush member is provided with a plate-like support portion and a brush portion protruding from the support portion and contacting the charging member,
The brush member reciprocates along an axial direction of the charging member at a contact portion between the brush portion and the charging member, and reciprocates along a direction perpendicular to the axial direction. apparatus.   The charging device according to claim 1, wherein the brush member reciprocates substantially linearly along the vertical direction.   The brush member reciprocates substantially linearly in a direction orthogonal to the axial direction of the charging member and along a tangential direction with respect to the peripheral surface of the charging member. The charging device according to 1.   The charging device according to claim 1, wherein the brush member is swingable about the axial direction and reciprocates in a substantially arc shape along the vertical direction.   5. The brush member according to claim 4, wherein the brush member reciprocates in a direction orthogonal to an axial direction of the charging member and along a normal direction with respect to a circumferential surface of the charging member. Charging device.   The charging device according to claim 1, wherein the brush portion has a plurality of gaps formed on the support portion by an electrostatic flocking method and inclined with respect to the vertical direction. .   An image forming apparatus comprising the charging device according to claim 1.

Images