JP2012032499A - Cleaning roller and image formation device equipped with the cleaning roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning roller for a charging device capable of preventing both ends of winding start and finish of an elastic member from removing from a shaft, thus avoiding poor cleaning of a charging roller or uneven charge due to uneven cleaning.SOLUTION: A cleaning roller is pressure-contacted to a charging roller that charges an image carrier to cleaning a surface of the charging roller. The cleaning roller comprises a shaft-shaped member, and a strip-shaped elastic member wound around the shaft-shaped member spirally at intervals. In the strip-shaped elastic member, an end for winding start or winding finish is cut off substantially parallel to a axis direction of the shaft member.

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. Such a roller charging device has the advantage that the amount of ozone generated is extremely small and the applied voltage required for the discharge is low, compared to non-contact charging by corona discharge. On the other hand, if a foreign substance such as a minute toner adheres to the surface of the charging roller in the roller charging device, the image carrier may be charged poorly and appear on the image as a white spot. 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. In the conventional cleaning roller, a cylindrical elastic member having the same length as that of the charging roller rotates in contact with the charging roller, so that the surface of the charging roller is rubbed and cleaned. However, 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. In addition, there is a problem in that the production of the elastic member in a cylindrical shape from the raw material of the massive elastic member is wasteful and costly during production.

  Therefore, for example, as shown in Patent Document 1, a cleaning roller is known in which a strip-shaped elastic member is wound around a shaft in a spiral manner with a gap therebetween. Since the spiral elastic member has a smaller contact area with the charging roller than the cylindrical elastic member, the load on the charging roller is reduced and the torque can be reduced. Further, the strip-shaped elastic member has no advantage in production, and can produce a larger number of sheets than a cylindrical shape from a lump of raw material of a certain size, which has the advantage of leading to cost reduction.

JP 2008-304729 A

  However, in a cleaning roller in which a strip-shaped elastic member is spirally wound around a shaft, the force that the elastic member bent along the shaft returns to the original shape is applied, and the passage of time or repeated use As a result, both ends of the elastic member at the start and end of the winding are peeled off from the shaft and lifted up. When both end portions of the elastic member are lifted in this way, the lifted portions hit the charging roller during rotation of the charging roller, so that the rotation pitch may become uneven and poor cleaning may occur. Further, when the lifted end portion enters the nip portion with the charging roller, it may be bent by contacting the charging roller, and may be further rotated along with the charging roller. In order to prevent the floating of both ends, it is possible to fix the winding start and winding end of the elastic member with a member, etc., but it will increase the cost due to the increase in the number of materials, from cylindrical to strip shape The meaning of the cost reduction by making it will be lost. Also, instead of spirally winding a strip-shaped elastic member around the shaft, as shown in Patent Document 1, the elastic member is formed in accordance with the shaft, both ends cover the entire circumference of the shaft, Although it is possible to process the part so as to have a spiral shape, it also requires a special molding process, which leads to an increase in cost.

  SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to start and end winding of an elastic member in a cleaning roller of a charging device provided with an elastic member spirally wound around a shaft. Is to prevent the charging roller from being peeled off from the shaft, thereby preventing charging roller uneven cleaning and uneven charging due to cleaning unevenness, thereby forming a stable quality image.

  In order to solve the above problems, a cleaning roller according to the present invention is a cleaning roller that is pressed against a charging roller that charges an image carrier and cleans the surface of the charging roller. A strip-like elastic member wound spirally at an interval, and the elastic member has its end portions at the start and end of winding cut off substantially parallel to the axial direction of the shaft-like member. It is characterized by. By having the end portion cut off substantially parallel to the shaft in this way, the adhesive force in the direction of pulling to the shaft can be increased with respect to the restoring force of the elastic member acting in the direction away from the shaft, and from the end portion. Peeling can be prevented.

  Moreover, it is preferable that the elastic member is gradually widened toward the end. Thereby, the adhesive force in the axial direction can be further increased.

  According to the present invention, the cleaning roller for cleaning the charging roller has a simple configuration by cutting off the winding start and winding end portions of the spirally wound elastic member so as to be substantially parallel to the shaft. Thus, peeling of the elastic member can be prevented, charging unevenness due to poor cleaning of the charging roller and uneven cleaning can be prevented, and a stable quality image can be formed.

1 is a schematic view of an image forming apparatus according to the present invention. Sectional drawing of the charging device according to the present invention FIG. 3 is a plan view of the cleaning roller according to the first embodiment. The top view of the elastic member terminal part concerning Example 1 The top view of the elastic member terminal part concerning Example 2 The top view of the elastic member terminal part concerning Example 3 The top view of the elastic member terminal part concerning Example 4 The perspective view of the elastic member terminal part which concerns on Example 5. FIG. Comparative experiment result table between Example 1 and Comparative Example The top view of the elastic member terminal part concerning a comparative example Sectional drawing of the cleaning roller concerning a comparative example Sectional drawing of the cleaning roller concerning a comparative example Sectional drawing of the cleaning roller concerning a comparative example

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 61 from the laser according to an image signal, and scans and exposes the surface of the photoconductor 10 in the axial direction according to image data.

  The developing device 70 includes a developing roller 71 provided in a non-contact manner on the photoconductor 10 and a housing 75 that stores 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 photoconductor 10, and the developer may be a one-component developer containing only toner.

  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 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 provided in parallel to the charging roller 31 and 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 discharge unevenness around a core metal 311, and has the same length as the photoreceptor 10. It is provided in parallel with the shaft, is pressed against and supported by the photoreceptor 10 by a bearing (not shown), and is driven to rotate by the photoreceptor 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 space 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 relative to 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. The toner remaining on the surface of the photoconductor 10 after passing through the transfer device 80 is collected by the cleaning device 90. However, fine toner and external additives such as external additives that could not be collected still reach the charging roller 31. Then, it 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. Cleaning roller

  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. A shaft 351 of the cleaning roller is made of a metal having a diameter of 4 mm, and a strip-shaped elastic member 352 having a width of 5 mm and a thickness of 3 mm is wound around the shaft 351 in a spiral manner with a space therebetween. The elastic member 352 is made of urethane sponge, and is affixed to a non-stretchable double-sided pressure-sensitive adhesive sheet 353 (not shown) and bonded and fixed to the shaft 351 by the double-sided pressure-sensitive adhesive sheet 353. The corners indicated by the dotted lines in FIG. 3 are cut off at both ends of the elastic member 352 at the beginning and end of winding so as to have end faces parallel to the shaft 351 in the wound state.

  FIG. 4 is a plan view of the cleaning roller 35 and shows the shape of one end of the elastic member 352 according to the first embodiment. The opposite end (not shown) has the same shape. As described above, the end portion of the elastic member 352 is cut off at one corner in a straight line and perpendicular to the thickness, and the thickness of the end surface is 3 mm, which is the same as the other portions. The end face 352a cut off in a straight line is fixed in parallel to the shaft 351 while being wound around the shaft 351. By having the end face 352a cut off linearly in parallel with the axial direction in this way, it is possible to prevent the elastic member 352 from being peeled off from the end due to repeated use or the like. The reason is as follows.

  FIG. 10 is a plan view of a cleaning roller 350 according to a comparative example. For comparison with the present embodiment, the elastic member 3520 has an end surface 3520b cut off in a direction perpendicular to the shaft while being wound around the shaft 3510.

  11 to 13 are sectional views of a cleaning roller 350 according to a comparative example. As shown in FIG. 13, the elastic member 3520 is bent and adhered along the curvature of the shaft 3510 by the double-sided pressure-sensitive adhesive sheet 3530. At both ends of the winding start and the winding end, a restoring force F in the normal direction, that is, the direction away from the axis, is generated by the force of the bent elastic member 3520 to return to the plane. If the restoring force F is smaller than the adhesive force f1 between the double-sided adhesive sheet 3530 and the elastic member 3520 and the adhesive force f2 between the elastic member 3520 and the shaft 3510, peeling does not occur. However, when the adhesive force f1 or f2 becomes smaller than the restoring force F of the elastic member 3520 due to repeated use or the like, the elastic member 3520 is peeled off.

  FIG. 11 shows a state where the adhesive force f1 between the elastic member 3520 and the double-sided pressure-sensitive adhesive sheet 3530 is reduced by repeated use or the like, and the elastic member 3520 is peeled off from the double-sided pressure-sensitive adhesive sheet 3530. If the elastic member 3520 is a foaming member such as urethane sponge, the adhesive surface with the double-sided pressure-sensitive adhesive sheet is reduced due to air bubbles, so the adhesive force f1 tends to be weak.

  FIG. 12 shows that the adhesive force f2 between the double-sided pressure-sensitive adhesive sheet 3530 and the shaft 3510 is reduced by repeated use or the like, and the elastic member 352 is peeled off from the shaft 3510 together with the double-sided pressure-sensitive adhesive sheet 3530. If the shaft 3510 is soiled when the double-sided pressure-sensitive adhesive sheet 3530 is wound around the shaft 3510, the adhesive force f2 between the shaft 3510 and the double-sided pressure-sensitive adhesive sheet 3530 tends to be weak.

  In the case of having the end surface 3520b cut off in the direction orthogonal to the axis as in the comparative example, the adhesive width in the axial direction at the start and end of winding of the elastic member 3520 is short, and the tip 3520c is particularly acute. Therefore, the restoring force F of the elastic member 3520 acting in the direction away from the axis is concentrated on the tip 3520c, and the elastic member 3520 and the double-sided pressure-sensitive adhesive sheet 3530 that attract the elastic member in the axial direction due to repeated use and the like. The adhesive force f1 between the two and the adhesive force f2 between the double-sided sheet 3530 and the shaft 3510 are both small, and peeling is likely to occur.

  Therefore, as shown in FIG. 4, the elastic member 352 according to the present embodiment has an end surface 352 a cut off in parallel with the axial direction in a wound state. By cutting off the winding start and winding end portions in parallel with the shaft in this way, the axial adhesive width on the end surface 352a becomes longer, so that the portion where the restoring force F of the elastic member 352 is concentrated is eliminated and the axial direction is eliminated. Widely distributed. Since the adhesive force f1 between the double-sided pressure-sensitive adhesive sheet 353 and the elastic member 352 that attracts the elastic member 352 to the shaft 351 or the adhesive force f2 between the shaft 351 and the double-sided adhesive tape extends in the axial direction of the end surface 352a, Even if it becomes smaller due to repeated use or the like, it is not lost to the restoring force F dispersed in the axial direction, and peeling from the end face 352a can be prevented.

  Here, with reference to FIG. 9, a description will be given of the results of a comparative experiment regarding the end peeling of the cleaning roller 35 according to the present embodiment and the cleaning roller 350 according to the comparative example. In the experiment, the state of the end after being left for a predetermined time at a temperature of 40 ° C. and a humidity of 95% was examined, and the state of the end after the heat cycle test was examined. The heat cycle test is a test in which a cycle in which the temperature is raised from 0 ° C. to 60 ° C. and lowered to 0 ° C. over 6 hours is defined as 1 cycle and this is performed for 6 cycles. Each of the cleaning roller 35 of the present embodiment and the conventional cleaning roller 350 is formed by winding a rectangular elastic member having a width of 5 mm and a thickness of 3 mm on a metallic shaft having a diameter of 4 mm in a spiral shape with a space therebetween. is there. The cleaning roller of this embodiment has an end portion cut off parallel to the axis as shown in FIG. 4, and the comparative example is an end portion cut off in a direction perpendicular to the axis as shown in FIG. In the comparative example, peeling from the end portion was found by leaving for 250 hours at a temperature of 40 ° C. and a humidity of 95%. However, in this example, there was no peeling even when left in the same environment for 250 hours, leaving for 500 hours, 750 No peeling from the end was found even after standing for 1000 hours. Also, in the heat cycle test, peeling occurred in the comparative example, whereas peeling did not occur in this example.

  In the present embodiment, the end surface 352a of the elastic member 352 is linearly cut parallel to the shaft 351. However, the angle of cutting is not limited to strict parallel, and the elastic member 352 is 30 degrees with respect to the shaft 351. It has been confirmed by the above experiment that the same effect can be obtained even if the angle is cut off at a certain angle.

  FIG. 5 is a plan view illustrating the end shape of the elastic member 354 of the cleaning roller according to the second embodiment. The opposite end (not shown) has the same shape. Since the cleaning roller according to the present embodiment is the same as the cleaning roller 35 according to the first embodiment except for the end shape of the elastic member of the cleaning roller, only the end shape will be described.

  The elastic member 354 gradually becomes wider from the end portion toward the end portion from the 7 mm portion in the length direction. The portion of 7 mm in the length direction from the end is a portion corresponding to the last half or the first half of the winding start or winding end. The end of the elastic member 354 is cut off linearly in parallel with the shaft 351 in the wound state, and the length of the cut end face 354a is about 10 mm. By cutting off the end portion in parallel with the shaft in this way, the axial adhesive width on the end surface 354a is increased, so that the restoring force F of the elastic member 354 is concentrated and there is no such portion, and it is widely dispersed in the axial direction. . Since the adhesive force f1 between the double-sided pressure-sensitive adhesive sheet 353 and the elastic member 354 that attracts the elastic member 354 to the shaft 351 or the adhesive force f2 between the shaft 351 and the double-sided adhesive tape extends in the axial direction of the end surface 354a. Even if it becomes smaller due to repeated use or the like, it will not lose to the restoring force F dispersed in the axial direction, and peeling from the end face 354a can be prevented.

  FIG. 6 is a plan view illustrating the end shape of the elastic member 356 of the cleaning roller according to the third embodiment. The opposite end (not shown) has the same shape. Since the cleaning roller according to the present embodiment is the same as the cleaning roller 35 according to the first embodiment except for the end shape of the elastic member of the cleaning roller, only the end shape will be described.

  The elastic member 356 has an end face 356a cut off parallel to the axis, and an end face 356b cut off at an angle of 90 degrees or more with the end face 356a. Since the elastic member 356 has the end surface 356a cut off in parallel with the axis, the adhesive width in the axial direction on the end surface 356a is increased, and thus the portion where the restoring force F of the elastic member 356 is concentrated is eliminated, and the axial direction Widely dispersed. Since the adhesive force f1 between the double-sided adhesive sheet 353 and the elastic member 356 that attracts the elastic member 356 to the shaft 351 or the adhesive force f2 between the shaft 351 and the double-sided adhesive tape extends in the axial direction of the end surface 356a, Even if it becomes smaller due to repeated use or the like, it will not lose to the restoring force F dispersed in the axial direction, and peeling from the end face 354a can be prevented.

  Further, since the elastic member 356 has the end surface 356b, an acute angle portion 356d composed of the end surface 356a and the outer side of the elastic member 356 wound around the shaft is cut off. The restoring force F of the elastic member 356 acting in a direction away from the axis is concentrated on the acute angle portion 356d, and there is a possibility that peeling occurs due to repeated use. However, by cutting off the acute angle portion 356d in this way, there is no portion where the restoring force is concentrated, and peeling from the acute angle portion 356d does not occur. Thereby, peeling from the elastic member 356 end part by repeated use etc. can be prevented.

  FIG. 7 is a plan view illustrating an end shape of the elastic member 358 of the cleaning roller according to the fourth embodiment. The opposite end (not shown) has the same shape. Since the cleaning roller according to the present embodiment is the same as the cleaning roller 35 according to the first embodiment except for the end shape of the elastic member of the cleaning roller, only the end shape will be described.

  The elastic member 358 has an arcuate end surface 358a cut off parallel to the axis. By cutting off into an arc shape in this way, the restoring force F of the elastic member 358 is concentrated and no part is applied, and the elastic member 358 is widely dispersed in the axial direction. The adhesive force f1 between the double-sided adhesive sheet 353 and the elastic member 358 for attracting the elastic member 358 to the shaft 351 or the adhesive force f2 between the shaft 351 and the double-sided adhesive tape extends in an arc shape in the axial direction of the end surface 358a. Therefore, even if it becomes smaller due to repeated use or the like, it is not lost to the restoring force F dispersed in the axial direction, and peeling from the end surface 358a can be prevented.

  FIG. 8 is a perspective view illustrating only the end shape of the elastic member 359 of the cleaning roller according to the fifth embodiment. The opposite end (not shown) has the same shape. Since the cleaning roller according to the present embodiment is the same as the cleaning roller 35 according to the first embodiment except for the end shape of the elastic member of the cleaning roller, only the end shape will be described.

  The end surface 359a of the elastic member 359 is cut off in parallel with the axis, and differs from the first embodiment only in that the length of about 7 mm from the end is gradually thinned. Since the elastic member 359 according to the present embodiment is gradually thinner toward the end portion, the restoring force F of the elastic member itself can be reduced. Thereby, peeling from the end surface 359a by repeated use etc. can be prevented further effectively.

  While the embodiments of the cleaning roller according to the present invention have been described above, it goes without saying that the cleaning roller is not limited to these embodiments. For example, the elastic member may be rubber instead of sponge. In foaming members such as urethane sponge, the adhesive surface with the double-sided PSA sheet is reduced due to air bubbles, so the adhesive force tends to be weak. It has a strong adhesive force and is suitable for preventing peeling. Further, the thickness and width of the elastic member are not limited to the present embodiment, and the shape of the end portion may be any one that widens the adhesive area in the axial direction with respect to the direction intersecting the axis where the restoring force F works, It is not limited to this embodiment.

DESCRIPTION OF SYMBOLS 10 Photoconductor 31 Charging roller 35 Cleaning roller 100 Image forming apparatus 351 Shaft 352, 354, 356, 358, 359 Elastic member

Claims (7)

A cleaning roller that is pressed against a charging roller that charges the image carrier and cleans the surface of the charging roller,
An axial member;
A strip-shaped elastic member wound spirally around the shaft-shaped member,
A cleaning roller, wherein the elastic member has an end portion at the start and end of winding cut off substantially parallel to the axial direction of the shaft-shaped member.   The cleaning roller according to claim 1, wherein the end portion is cut off linearly.   The cleaning roller according to claim 1, wherein the elastic member is gradually widened toward the end portion.   The elastic member further includes an end portion cut off at an angle of 90 degrees or more with respect to an end portion cut off substantially parallel to the axial direction of the shaft-like member. The cleaning roller according to crab.   The cleaning roller according to claim 1, wherein the elastic member is gradually thinner toward an end portion.   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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