JP2011203569A - Cleaning roller and image forming apparatus having the cleaning roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning roller, which can prevent charging failure resulting from soil or filming on a charging roller, by preventing accumulation of soil on the cleaning roller and improving its cleaning ability, in the cleaning roller for a charging device having a spiral elastic member, and to provide an image forming apparatus equipped with the cleaning roller.SOLUTION: The cleaning roller, for cleaning the surface of a charging roller for charging an image carrier, includes a shaft-like member, and the elastic member spirally wound around the shaft-like member with a gap between them. The elastic member has a plurality of cuts on its surface.

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to a cleaning roller that cleans the surface of a charging roller that charges the surface of an image carrier such as a photoreceptor, and an image forming apparatus that includes the cleaning roller.

  As an apparatus for charging the surface of an image carrier such as a photoconductor in an image forming apparatus such as a copying machine, a printer, and a facsimile using an electrophotographic system, a roller charging device disposed in contact with or close to the image carrier is used. Are known. In such a roller charging device, if a foreign matter such as a minute toner adheres to the surface of the charging roller, the image carrier may be poorly charged and may appear as a white spot on the image. Further, there is a case where toner or an external additive contained in the toner adheres to the surface of the charging roller in a thin layer, causing charging performance to change and uneven charging.

  In order to prevent such charging failure, an image forming apparatus provided with a cleaning roller for cleaning the surface of the charging roller is known. The cleaning roller has the same length as the charging roller, and cleans the surface of the charging roller by rotating in contact with the charging roller. As for the shape of the cleaning roller, a cylindrical elastic member having a shaft penetrating, or a strip-shaped elastic member spirally wound around a shaft with a gap is known. Since the cylindrical elastic member is pressed against the charging roller so as to secure a certain amount of biting, there is a problem that the torque of the charging roller increases and rotation failure occurs. On the other hand, since the helical elastic member has a smaller contact area with the charging roller than the cylindrical elastic member, the torque of the charging roller can be reduced, but the unit for cleaning the same amount of dirt can be reduced. Since accumulation of dirt per area increases, there is a problem that dirt is more easily produced than a cylindrical one. In addition, the cleaning roller made of a spiral elastic member has a problem that its cleaning ability is inferior to that of a cylindrical roller because the contact area per unit time with the charging roller is reduced. As for the latter problem, for example, as described in Patent Document 1, there has been proposed a method of improving the cleaning capability by providing a peripheral speed difference between the charging roller and the cleaning roller.

JP 2008-70532 A

  However, according to the method of providing a difference in the peripheral speed between the charging roller and the cleaning roller as described above, the cleaning ability is certainly improved, but the problem that the cleaning roller tends to become dirty cannot be solved.

  The present invention has been made in view of such a problem, and an object of the present invention is to prevent the accumulation of dirt on the cleaning roller and to clean the cleaning roller of the charging device provided with a spiral elastic member. An object of the present invention is to provide an image forming apparatus capable of preventing charging failure due to dirt on the charging roller or filming by improving the ability.

  In order to solve the above-mentioned problems, a cleaning roller according to the present invention is a cleaning roller for cleaning the surface of a charging roller for charging an image carrier, and a spiral member with a gap formed between the shaft member and the shaft member. And an elastic member wound around the elastic member, wherein the elastic member has a plurality of cuts on a surface thereof.

  By having a plurality of cuts in this way, when the cleaning roller bounces off foreign matter such as toner and external additives from the surface of the charging roller, the force to bounce off the foreign matter is increased and the cleaning roller's cleaning ability can be improved. In addition, foreign matter can be blown off to the shaft portion of the cleaning roller around which the elastic member is not wound, so that accumulation of dirt on the cleaning roller can be prevented.

  Each cut of the elastic member may be in an oblique direction intersecting with the axis of the cleaning roller, or may be arcuate. Even when the cleaning roller is pressed against the charging roller during stoppage and a force is applied in parallel to the shaft, there is a notch in the direction intersecting the shaft or in an arc shape, so that the incision of the elastic member is fully opened. Can be prevented.

  Further, the cut of the elastic member may be provided only at the end of the elastic member in the width direction. By providing a cut only at the end in the width direction, when the cleaning roller is pressed against the charging roller at the time of stopping, even if each cut is opened, there is a portion where there is no cut, so that the entire elastic member is not deformed. The creep of the cleaning roller can be prevented.

  The cleaning roller may be configured to rotate following the rotation of the charging roller. By rotating the charging roller in this way, the surface of the charging roller can be cleaned with a simple configuration.

  According to the present invention, in the spiral cleaning roller for cleaning the charging roller, it is possible to prevent the accumulation of dirt on the cleaning roller with a simple configuration and to improve the cleaning ability of the cleaning roller. It is possible to prevent charging failure due to contamination of the roller and filming, and to form an image with stable quality.

1 is a schematic view of an image forming apparatus according to the present invention. It is sectional drawing of the charging device which concerns on this invention. It is a top view of the cleaning roller which concerns on this invention. It is the figure which showed a mode that the cleaning roller which concerns on this invention removes a foreign material from a charging roller. It is a graph showing the comparison of the cleaning capability of the cleaning roller which concerns on this invention. It is the top view which showed another embodiment of the cleaning roller which concerns on this invention. It is the top view which showed another embodiment of the cleaning roller which concerns on this invention. It is the top view which showed another embodiment of the cleaning roller which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1. Image Forming Apparatus FIG. 1 schematically shows an electrophotographic image forming apparatus according to the present invention. The image forming apparatus 100 is a printer that forms an image on a sheet P based on image information sent from an external terminal device (not shown). The image forming apparatus includes a copying machine, a printer, a facsimile, and the like. Any of the multi-function machines having multiple functions may be used.

  The image forming apparatus 100 includes a photoreceptor 10 that is an electrostatic latent image carrier. The photoreceptor 10 includes, for example, a cylindrical conductive support and a negatively chargeable OPC photosensitive layer formed on the outside thereof, and is driven to rotate in the direction of arrow a in the figure by a motor (not shown). Around the photoconductor 10, a charging device 30, an exposure device 60, a developing device 70, a transfer device 80, and a cleaning device 90 are arranged along the rotation direction of the photoconductor 10.

  The charging device 30 includes a cylindrical charging roller 31 and a cleaning roller 35 that cleans the charging roller 31. The charging roller 31 is provided in contact with the photoconductor 10 and is driven to rotate by the photoconductor 10. The charging device 30 will be described in detail later.

  The exposure device 60 includes a laser, a mirror, and a lens (not shown), emits light from the laser according to an image signal, and scans the surface of the photoconductor 10 in the axial direction.

  The developing device 70 includes a developing roller 71 provided in non-contact with the photoreceptor 10 and a housing 75 including a two-component developer including toner and a carrier. The developing device is not limited to such a configuration. For example, the developing roller may be in contact with the photoreceptor 10, and the developer may be a single component of toner only.

  The transfer device 80 includes a transfer roller 81 pressed against the photosensitive member 10, and applies a voltage having a polarity opposite to that of the toner from the back side of the paper P conveyed from the feeding unit 20 to transfer the toner image onto the paper P. To do. The transfer device is not limited to such a configuration. For example, the transfer device may primarily transfer the toner image onto the sheet after the primary transfer onto the intermediate transfer belt, and uses corona transfer instead of roller transfer. May be.

  The cleaning device 90 has a cleaning blade 91 made of an elastic member, and the cleaning blade 91 is pressed against the surface of the photoconductor 10 in a direction opposite to the rotation direction of the photoconductor 10 (arrow a in the figure). The cleaning device is not limited to such a blade system, and may be a roller or brush system, for example.

  In the image forming apparatus 100 having such a configuration, when the photoconductor 10 rotates in the direction of arrow a in the drawing based on the driving of a motor (not shown), the surface of the photoconductor 10 passing through the charging device 30 is charged to a predetermined potential and charged. The surface of the photoreceptor 10 thus exposed is exposed by a laser beam 61 emitted from the exposure device 60 in accordance with an image signal. On the surface of the photoconductor 10, an electrostatic latent image is formed at a portion where the potential is attenuated by the emission of the laser beam 61. The electrostatic latent image is conveyed to the developing device 70 along with the rotation of the photoconductor 10, and the developing roller. The toner supplied by 71 adheres to the electrostatic latent image to be visualized. The visualized toner image is conveyed to the transfer device 80 as the photosensitive member 10 rotates, and is transferred onto the paper P conveyed from the paper supply unit 20. When the photoconductor 10 further rotates, the surface of the photoconductor 10 on which the toner image is transferred onto the paper P by the transfer device 80 reaches the cleaning device 90, and the remaining toner that is not transferred is removed. On the other hand, the paper P on which the toner image has been transferred by the transfer device 80 is conveyed to the fixing device 40 where the toner image is fixed and discharged to the paper discharge tray 50.

2. Next, the charging device will be described in detail. FIG. 2 is a cross-sectional view of the charging device. The charging device includes a cylindrical charging roller 31 and a cleaning roller 35 that cleans the charging roller 31. The charging roller 31 is formed by forming a conductive elastic body layer 312 and a surface layer 313 for preventing contamination around a core bar 311. The charging roller 31 has the same length as the photoreceptor 10 and has a shaft of the photoreceptor 10. And is supported by being pressed against the photoconductor 10 by a bearing (not shown), and is driven to rotate by the photoconductor 10. The charging roller is not limited to the configuration in contact with the photoconductor, and may be configured to provide a minute gap between the charging roller and the charging roller without being in contact with the photoconductor.

  The cleaning roller 35 includes a shaft 351 and an elastic member 352 wound around the shaft 351 in a spiral manner with a gap therebetween. The cleaning roller 35 has the same length as the charging roller 31, is supported by being pressed against the charging roller 31 by a bearing (not shown), and is driven to rotate by the charging roller 31.

  In the charging device having such a configuration, when the photosensitive member 10 is rotated by driving a motor (not shown), the charging roller 31 disposed in contact with the photosensitive member 10 is driven to rotate. When a predetermined voltage is applied to the charging roller 31, a discharge is generated in a minute gap formed in the vicinity of the pressure contact portion between the charging roller 31 and the photoconductor 10, and the surface of the photoconductor 10 is charged. As described above, the toner remaining on the surface of the photoconductor 10 after passing through the transfer device 80 is collected by the cleaning device 90, but fine toner and external additives such as external additives that could not be collected still remain on the charging roller. 31, and adheres to the surface of the charging roller 31. The foreign matter adhering to the surface of the charging roller 31 is removed by the cleaning roller 35 that rotates following the charging roller 31.

3. Next, the cleaning roller 35 which is a characteristic part of the present invention will be described in detail. FIG. 3 is a plan view of the cleaning roller 35 viewed from a direction orthogonal to the axis. The shaft 351 of the cleaning roller is made of a metal having a diameter of 4 mm, and an elastic member 352 is formed around the shaft 351 by winding a rectangular urethane sponge having a width of 5 mm and a thickness of 3 mm in a spiral manner with a gap therebetween. Yes. The urethane sponge is affixed on a non-stretchable double-sided pressure-sensitive adhesive sheet, and is adhesively fixed to the shaft 351 by the double-sided pressure-sensitive adhesive sheet. The elastic member 352 is wound around the shaft 351, and a plurality of cuts 352a are formed on the surface thereof in parallel with the shaft. The notches 352a have a depth of 2.5 mm in the thickness direction of the elastic member 352 and a length in the entire width direction of the elastic member 352, and are formed on the surface of the elastic member 352 in parallel with each other at an interval of 2 mm.

  FIG. 4 shows a state where the elastic member 352 of the cleaning roller 35 blows off foreign matters such as toner and external additives on the surface of the charging roller 31. As shown in FIG. 4A, when the charging roller 31 rotates, the cleaning roller 35 is driven to rotate, and the foreign matter 77 a attached to the surface of the charging roller 31 is sandwiched between the elastic member 352 and the charging roller 31. Another foreign matter 77b enters the notch 352a in which the elastic member 352 is opened. When the charging roller 31 further rotates, the cleaning roller 35 is driven to rotate. As shown in FIG. 4B, when the surface of the elastic member 352 moves away from the charging roller 31, the elastic member 352 pressed by the nip portion is restored. Due to the elasticity to be applied, the foreign matter 77 a sandwiched between the nip portions and the foreign matter 77 b that has entered the notch 352 a are bounced off and removed from the surface of the charging roller 31.

  As described above, the cleaning roller 35 according to the present invention is provided with the notch 352a in the elastic member 352, so that the elastic member 352 itself has an elastic force, and the swinging force of the notch 352a is applied. The force to blow off becomes large, and a good cleaning ability for the charging roller 31 can be secured.

  In addition, the cleaning roller 35 has a notch 352a opened at the nip portion with the charging roller 31 and a foreign matter 77a such as toner or an external additive enters the open notch 352a. The cleaning ability can be improved as compared to the one without an increase.

  Further, since the elastic member 352 is wound around the shaft 351 in a spiral shape with the elastic member 352 being wound in a spiral shape, the cleaning roller 35 can blow off foreign matter into a gap portion where the elastic member 352 is not wound, Accumulation of dirt on the elastic member 352 can be reduced.

  Here, with reference to FIG. 5, the result of the comparative experiment regarding the cleaning ability of the cleaning roller 35 according to the present embodiment will be described. In this experiment, a cleaning roller (a broken line “■” in the figure) in which a shaft is passed through a cylindrical sponge, and a cleaning roller 35 (a broken line in the figure) in which the sponge is spirally wound around the shaft to make a cut. “●”) and a spiral cleaning roller obtained by removing the notch from the cleaning roller of the present embodiment (a broken line “▲” in the figure) were compared. Here, each cleaning roller was brought into pressure contact with the charging roller to which the external additive was adhered, and the charging roller was rotated for a predetermined time to measure the change in the amount of dirt removed. Referring to FIG. 5, the cleaning roller 35 having the notch of the present embodiment (broken line “●” in the figure) has a higher cleaning ability than the spiral cleaning roller having no notch (broken line “▲” in the figure). It can be seen that it has a cleaning ability comparable to that of a cylindrical cleaning roller (broken line “■” in the figure) having a large contact area with the charging roller.

  The cuts into the elastic member 352 are not limited to the above example, and a plurality of cuts 352b may be made in an oblique direction intersecting with the shaft 351 as shown in FIG. 6, as shown in FIG. A plurality of cuts 352c may be formed in an arc shape. In this way, there is a cut in the direction intersecting the axis or in an arc shape, the cleaning roller is pressed against the charging roller at the time of stopping, and even if a force is applied parallel to the axis, each cut does not open completely, The cleaning roller can be prevented from creeping.

  In addition, a cut may be made only at the end of the elastic member 352 in the width direction. For example, cuts 352d similar to both ends may be made parallel to the axis as shown in FIG. 8A, or cuts 352e may be made alternately from both ends parallel to the axis as shown in FIG. 8B. As shown in FIG. 8C, the cuts 352f may be alternately made from both ends in an oblique direction intersecting with the axis. Further, each cut may be an arc instead of a straight line. By providing a cut only at the end in the width direction in this way, when the cleaning roller is pressed against the charging roller at the time of stopping, the entire elastic member is deformed because there is a portion that is not cut even if each cut is opened. This prevents the cleaning roller from creeping.

  The embodiments of the cleaning roller according to the present invention have been described above. However, the cleaning roller is not limited to these embodiments. For example, the elastic member may be a rubber instead of a sponge, and the thickness and width may be the same. It is not limited to the form. Needless to say, the shape and depth of the cut are not limited to the present embodiment.

10: Photoconductor 31: Charging roller 35: Cleaning roller 351: Cleaning roller shaft 352: Elastic members 352a, 352b, 352c, 352d, 352e, 352f: Cutting of elastic member

Claims (6)

A cleaning roller for cleaning the surface of a charging roller for charging the image carrier,
A shaft-shaped member, and an elastic member wound spirally around the shaft-shaped member,
The elastic member has a plurality of cuts on the surface thereof.   The cleaning roller according to claim 1, wherein each cut of the elastic member is in an oblique direction intersecting with an axis of the cleaning roller.   The cleaning roller according to claim 1, wherein the cut of the elastic member has an arc shape.   The cleaning roller according to claim 1, wherein the cut of the elastic member is provided only at an end in the width direction of the elastic member.   The cleaning roller according to claim 1, wherein the cleaning roller rotates following the rotation of a charging roller.   An image forming apparatus comprising the cleaning roller according to claim 1.

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