JP2008151864A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of obtaining a satisfactory image for a long period of time by restricting an amount of bite of a cleaning roller into a photoreceptor drum even if the cleaning roller causes biased wear only in its axial direction, thereby preventing extreme wear in one area. <P>SOLUTION: An adjustment member 35 is provided for restricting a movable bearing 32 supporting the cleaning roller 17, from rocking in the direction of the photoreceptor drum 14. When the apparatus is assembled, the position of the adjustment member 35 is adjusted and fixed so that a predetermined amount of gap is formed between the movable bearing 32 and adjustment member 35, the amount being appropriately determined depending on the materials of the photoreceptor drum 14 and cleaning roller 17 and the specifications of the image forming apparatus 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a copying machine, and a facsimile, and in particular, a cleaning roller for removing toner remaining on an image carrier after transferring a toner image on the image carrier to a sheet or the like. The present invention relates to an image forming apparatus.

  In an electrophotographic image forming apparatus, an electrostatic latent image corresponding to image information is formed on a photosensitive drum, which is an image carrier, and a toner image is formed by developing the electrostatic latent image with a developing device. Is done. As a method for transferring the toner image to the paper, the paper is inserted into a transfer nip portion formed by pressing the transfer member against the photosensitive drum, and a transfer bias is applied to the transfer member. A method of contacting and transferring a toner image formed on the surface of a photosensitive drum to a sheet is widely used.

  In such a transfer method, a small amount of toner may remain on the surface of the photosensitive drum without being transferred to the paper after the toner image is transferred to the paper. Therefore, it is necessary to remove it. As a cleaning method used for such a purpose, a method in which a cleaning blade is brought into contact with the surface of the photosensitive drum to remove the residual toner is generally used, but the residual is obtained by pressing a cleaning roller against the surface of the photosensitive drum. A method of moving and collecting toner is also known.

  In addition, when amorphous silicon is used as the photosensitive layer, the discharge product formed on the surface of the photosensitive drum adsorbs moisture due to its characteristics, and image flow tends to occur, so the cleaning blade and cleaning roller are used in combination. Then, a small amount of abrasive is mixed in the toner, the residual toner is removed by the cleaning blade and the cleaning roller, and the toner is carried on the cleaning roller, and cleaning is performed so that the discharge product on the surface of the photoreceptor is polished by the toner. How to do is known.

  Here, in order to press the cleaning roller against the surface of the photosensitive drum, for example, one end side of an arm member that can rotate around both ends of the cleaning roller around a support shaft arranged in parallel with the rotating shaft of the photosensitive drum And is configured to be swingable in a direction away from and in contact with the photosensitive drum peripheral surface, and a biasing force is applied to the photosensitive drum peripheral surface side by attaching a biasing spring to the other end side of the arm member. Is disclosed (for example, Patent Document 1).

  However, in the configuration as described above, the support shaft for rotatably supporting the arm member may not be parallel to the rotation shaft of the photosensitive drum due to an assembly error or the like. Since a certain amount of play is required to support the rotatable shaft, it becomes more difficult to achieve parallelism between the support shaft and the photosensitive drum. Even when the parallelism is achieved, if the circumferential surface of the photosensitive drum is eccentric, it is impossible to cause the cleaning roller to follow the eccentricity.

  Further, the cleaning roller needs to be rotated at a peripheral speed different from that of the photosensitive drum. A driving system is connected to one shaft end of the cleaning roller, but the driving system is connected to the end where the driving system is connected. The combined force of the torque reaction force in the tangential direction of the cleaning roller due to rotation of the cleaning roller and the biasing force vector of the biasing spring attached to the arm member acts on the side connected to the drive system, and the biasing spring at the other shaft end As a result, the pressing force of the cleaning roller against the photosensitive drum becomes non-uniform in the axial direction, so that smooth cleaning could not be performed.

  Therefore, various techniques have been proposed to smoothly clean the surface of the photosensitive drum even when the circumferential surface of the photosensitive drum is eccentric as described above. For example, Patent Document 2 removes residual toner. A pair of bearings are disposed at both ends of the cleaning roller in the axial direction, and these bearings are supported by the guide portions so as to be slidable only in a direction to be in contact with and away from the circumferential surface of the photosensitive drum. There is disclosed an image forming apparatus in which a spring member that is biased to the side is provided, and the biasing force of each spring member is made different in response to a torque reaction force obtained from a drive system that applies a rotational force to the cleaning roller.

According to this, the cleaning roller is configured to be swingable along a plane parallel to the photosensitive drum axis in a direction to be separated from and in contact with the circumferential surface of the photosensitive drum via the bearing and the guide portion. It is possible to obtain uniform line contact regardless of the eccentricity of the peripheral surface of the body drum and the variation in the hardness distribution of the cleaning roller. In addition, when the drive system is attached to one shaft end of the cleaning roller, The contact pressure with the body drum can be maintained evenly in the axial direction.
JP 61-114269 A Japanese Patent Laid-Open No. 5-289581

  However, in the image forming apparatus described in Patent Document 2, the cleaning roller can be brought into line contact with the photosensitive drum, and a uniform pressing force can be obtained in the axial direction. If the cleaning roller is unevenly worn in the direction of its rotation axis, it will continue to be pressed against the photosensitive drum as it is, and the cleaning roller will be extremely scraped off and slid. As a result, the rubbing performance becomes non-uniform in the axial direction. As a result, the wear amount of the photosensitive drum becomes non-uniform in the axial direction, and there is a possibility that the sensitivity difference and the service life may be adversely affected.

  In the present invention, in view of the above-described circumstances, even when the cleaning roller is unevenly worn in the axial direction, the amount of the cleaning roller biting into the photosensitive drum is regulated to prevent extreme one-side scraping for a long time. An object of the present invention is to provide an image forming apparatus capable of obtaining a good image over a wide range.

  In order to achieve the above object, the present invention provides an image carrier on which a toner image is carried, a cleaning roller for rubbing the surface of the image carrier to remove residual toner, and both ends of the cleaning roller in the rotational axis direction. And a pair of movable bearings configured to rotatably support the cleaning roller and to move the cleaning roller in a direction in contact with and away from the image carrier, the movable bearing, and the cleaning roller In the image forming apparatus provided with an urging unit that urges the image bearing member in a direction of contact with the image bearing member, the cleaning roller of the movable bearing is disposed in the vicinity of at least one of the movable bearings. It is characterized in that an adjustment member is provided that can restrict the movement in the direction of contact to a predetermined position.

  According to the present invention, in the image forming apparatus configured as described above, the adjustment member is formed in an arc shape on a side facing the movable bearing.

  According to the first configuration of the present invention, the adjustment member restricts the movement of the movable bearing supporting the cleaning roller in the direction of the image carrier to a predetermined position. For this reason, even if the cleaning roller is unevenly worn in the direction of its rotational axis and continues to be pressed against the image carrier by the biasing means, the movable bearing on the scraped side moves at a position where it abuts against the adjusting member. Is restricted and the other side is waited for to be scraped off at that position, so that extreme scuffing is prevented from occurring on the image carrier or the cleaning roller, and a good image can be obtained over a long period of time. it can.

  According to the second configuration of the present invention, in the image forming apparatus having the first configuration, the side of the adjustment member facing the movable bearing is formed in an arc shape, thereby adjusting the position of the adjustment member. Since the adjustment member always comes into contact with the gap gauge used at this time at one point, the position adjustment of the adjustment member can be performed more accurately.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating the overall configuration of an image forming apparatus according to the present invention, and the right side is illustrated as the front side of the image forming apparatus. In this embodiment, a laser beam printer is exemplified as an example of the image forming apparatus. However, it goes without saying that the present invention can be applied to a copying machine, a facsimile machine, or the like other than the printer.

  As shown in FIG. 1, the image forming apparatus 1 includes a paper feed cassette 2 that accommodates sheets stacked on the lower part of the main body. Above this paper feed cassette 2 is formed a paper transport path 4 that extends substantially horizontally from the front of the main body to the rear of the main body and further extends upward to reach the paper discharge section 3 formed on the upper surface of the main body. A pickup roller 5, a feed roller 6, an intermediate conveyance roller 7, a registration roller pair 8, an image forming unit 9, an image fixing unit 10, and a discharge roller pair 11 are arranged in this order from the upstream side along the conveyance path.

  The paper feed cassette 2 is provided with a paper stacking plate 12 that is rotatably supported with respect to the paper feed cassette 2 by a rotation fulcrum 12a provided at the rear end in the paper transport direction. The sheet thus formed is pressed against the pickup roller 5. A retard roller 13 is disposed in front of the paper feed cassette 2 so as to be in pressure contact with the feed roller 6, and when a plurality of sheets are simultaneously fed by the pickup roller 5, A sheet is rolled by the feed roller 6 and the retard roller 13, and only the uppermost sheet is conveyed.

  Then, the sheet fed by the feed roller 6 and the retard roller 13 is conveyed to the registration roller pair 8 by changing the conveyance direction to the rear of the apparatus by the intermediate conveyance roller 7, and the timing is adjusted by the registration roller pair 8. Are supplied to the image forming unit 9.

  The image forming unit 9 forms a predetermined toner image on a sheet by an electrophotographic process. The image forming unit 9 is a photosensitive drum 14 that is an image carrier that is rotatably supported in the clockwise direction in FIG. Above the charger 15, the developing device 16, the cleaning roller 17, the transfer roller 18 disposed so as to face the photosensitive drum 14 across the sheet conveyance path 4, and the photosensitive drum 14. A laser scanning unit (LSU) 19 is disposed, and a toner container 20 for supplying toner to the developing device 16 is disposed above the developing device 16.

  A scorotron charging device using a corona discharge charger is used as the charger 15, and tungsten or stainless steel is placed inside a metal shield case having an opening formed in a bowl shape facing the photosensitive drum. A corona wire and a grid, which are discharge members composed of, etc., are provided, a predetermined voltage is applied to the corona wire to generate a corona discharge, and a voltage is applied to the grid to control the amount of electrons. As a result, the surface of the photosensitive drum 14 is uniformly charged with a predetermined polarity and potential.

  Next, an electrostatic latent image is formed on the photosensitive drum 14 by a laser beam from a laser scanning unit (LSU) 19 based on the input image data, and toner is attached to the electrostatic latent image by the developing device 16. A toner image is formed on the surface of the photosensitive drum 14, and the toner image on the surface of the photosensitive drum 14 is supplied to the transfer position formed in the nip portion between the photosensitive drum 14 and the transfer roller 18 by the transfer roller 18. Transferred to paper.

  The sheet onto which the toner image has been transferred is separated from the photosensitive drum 14 and conveyed toward the image fixing unit 10. The image fixing unit 10 is disposed on the downstream side of the image forming unit 9 in the sheet conveyance direction. The sheet on which the toner image is transferred in the image forming unit 9 is a heating roller 21 provided in the image fixing unit 10. In addition, the toner image that is sandwiched and heated by the pressure roller 22 pressed against the heating roller 21 is fixed.

  The paper on which the image is formed in the image forming unit 9 and the image fixing unit 10 is discharged to the paper discharge unit 3 by the discharge roller pair 11. On the other hand, after the transfer, the toner remaining on the surface of the photosensitive drum 14 is removed by the cleaning roller 17. The photosensitive drum 14 is charged again by the charger 15 and image formation is performed in the same manner.

  Next, the drum unit used in the image forming apparatus of the present invention will be described with reference to FIG. FIG. 2 is a perspective view of the drum unit.

  As shown in FIG. 2, the photosensitive drum 14, the cleaning roller 17, and the like are arranged in a frame 31 to constitute a drum unit 30 that can be drawn out from the main body of the image forming apparatus 1. The photosensitive drum 14 is rotatably supported in the frame 31 with both ends of the rotation shaft 14 a supported by the frame 31. A driving gear (not shown) is provided at one end of the photosensitive drum 14. When the drum unit 30 is attached to the main body of the image forming apparatus 1, the driving gear is provided in the main body of the image forming apparatus 1 (not shown). Connected with driving means.

  The cleaning roller 17 is supported by a movable bearing 32 attached to the frame body 31 at both ends of the rotating shaft 17a, and is rotatably held in the frame body 31. A driving gear (not shown) is provided at one end of the cleaning roller 17. The driving gear of the cleaning roller 17 is drivingly connected to the driving gear of the photosensitive drum 14, and the photosensitive drum 14 is in the image forming apparatus 1. When driven by the driving means, the photosensitive drum 14 is configured to rotate at a different peripheral speed.

  The movable bearings 32 provided on both side surfaces of the frame 31 are provided with circular holes 32a and 32b at both ends, respectively, and the rotating shaft 17a of the cleaning roller 17 is supported in one circular hole 32a. The other circular hole 32b is extrapolated to a fulcrum pin 33 formed on the side surface of the frame 31 so as to be parallel to the rotation shaft 14a of the photosensitive drum 14, so that the cleaning roller is centered on the fulcrum pin 33. 17 can be swung in a direction to be separated from and in contact with the circumferential surface of the photosensitive drum 14. An urging spring 34 is stretched so as to connect the end of the movable bearing 32 and a hooking portion (not shown) provided on the frame 31, and the cleaning roller 17 is pressed against the photosensitive drum 14 with a predetermined pressure. Has been.

  Here, when the cleaning roller 17 is unevenly worn in the direction of the rotation axis due to a dimensional error at the time of manufacture or the like, if it continues to be pressed against the photosensitive drum 14 by the biasing spring 34, the photosensitive roller 14 is exposed to light. In some cases, extreme scraping occurs on the photosensitive drum 14 or the cleaning roller 17, and the photosensitive drum 14 or the cleaning roller 17 may have to be replaced in a period that is significantly shorter than the design life. Therefore, the present invention is characterized in that an adjustment member 35 is provided that can regulate the swing of the movable bearing 32 that supports the cleaning roller 17 in the direction of the photosensitive drum 14 to a predetermined position.

  Hereinafter, the adjustment member attached to the drum unit and a method of attaching the adjustment member will be described with reference to FIGS. 3A and 3B are views showing the adjustment member, where FIG. 3A is a plan view and FIG. 3B is a perspective view. 4 and 5 are side views of the drum unit. FIG. 4 shows a state before adjusting the gap between the movable bearing and the adjusting member, and FIG. 5 shows a state after adjusting the gap between the movable bearing and the adjusting member. For convenience of explanation, in FIGS. 4 and 5, attention is paid only to the movable bearing and the adjusting member disposed on one side surface of the frame, and the movable bearing and the adjusting member disposed on the other side surface. Although explanation is omitted, the configuration is the same except that both are arranged symmetrically.

  As shown in FIG. 3, the adjustment member 35 is a substantially U-shaped plate member whose back side 35 a is formed in an arc shape, and a circular hole 35 b through which the fixing screw 36 is inserted at one end. A long hole 35c through which the fixing screw 37 (see FIG. 2) is inserted is provided at the other end. The long hole 35c is elongated in a direction perpendicular to the direction in which the circular holes 35b and the long holes 35c are arranged so that the adjusting member 35 can rotate around the fixing screw 36 as described later. Is formed.

  When the adjustment member 35 is attached to the frame 31, first, as shown in FIG. 4, the adjustment member 35 is disposed so that the back side 35 a faces the movable bearing 32 and the fixing screw 36 is circular. By passing through the hole 35 b and screwing into a screw hole (not shown) provided in the frame body 31, the frame body 31 is held rotatably about the fixing screw 36. At this time, the movable bearing 32 is positioned so that the cleaning roller 17 comes into line contact with the photosensitive drum 14 by the biasing force of the biasing spring 34.

  Next, as shown in FIG. 5, the adjustment member 35 is rotated and is appropriately determined between the movable bearing 32 and the adjustment member 35 according to the material of the photosensitive drum 14 and the cleaning roller 17 and the specification of the image forming apparatus 1. The position of the adjustment member 35 is adjusted using a gap gauge or the like so that a predetermined gap amount is formed. Here, since the back side 35a of the adjustment member 35 facing the movable bearing 32 is formed in an arc shape, the gap gauge used for adjustment and the adjustment member 35 are always in contact at one point. Adjustment can be made more accurately.

  Then, after adjusting the position of the adjustment member 35, the fixing screw 37 is threaded into the screw hole 38 provided in the frame body 31 through the elongated hole 35 c to fix the adjustment member 35 to the frame body 31. To do. As a result, when the drum unit 30 is mounted on the image forming apparatus 1 and the photosensitive drum 14 and the cleaning roller 17 are worn by the image forming operation, the movable bearing 32 is adjusted by the biasing force of the biasing spring 34. However, the swing of the movable bearing 32 is restricted to a position where the movable bearing 32 contacts the adjustment member 35.

  As described above, the adjustment member 35 restricts the swing of the movable bearing 32 that supports the cleaning roller 17 in the direction of the photosensitive drum 14 to a predetermined position. Thus, even if the cleaning roller 17 is unevenly worn in the direction of the rotation axis and is continuously pressed against the photosensitive drum 14 by the urging spring 34, the shaved movable bearing 32 contacts the adjusting member 35. Oscillation is restricted at the contact position, and the other is scraped off at that position. Therefore, it is possible to prevent the photosensitive drum 14 or the cleaning roller 17 from being extremely scraped, and for a long period of time. A good image can be obtained.

  The present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above embodiment, the movable bearing 32 that supports the cleaning roller 17 is Although it is supported so as to be swingable with respect to the frame 31, it is also possible to support the cleaning roller 17 so as to be slidable in a direction in which the cleaning roller 17 is separated from and contacting the photosensitive drum 14. In the above-described embodiment, the adjustment member 35 that restricts the swing of the movable bearing 32 is disposed on both side surfaces of the frame body 31, but a driving gear that transmits driving to one end portion of the cleaning roller 17 is provided. In this case, the driving force is connected to one end of the cleaning roller 17 because the pressing force on the photosensitive drum 14 increases and wears faster at the end where the driving gear is provided. In such a case, it is only necessary to provide the adjustment member 35 at least on the end side.

  In the above-described embodiment, the image forming apparatus 1 in which the photosensitive drum 14, the cleaning roller 17, and the like are configured as the drum unit 30 has been described as an example. However, the photosensitive drum 14, the cleaning roller 17, and the like are described. The present invention can also be applied to an image forming apparatus that is not unitized.

  The present invention can be used in an image forming apparatus such as a printer, a copying machine, and a facsimile, and in particular, cleaning that removes toner remaining on an image carrier after the toner image on the image carrier is transferred to a sheet or the like. It can be used in an image forming apparatus having a roller.

FIG. 1 is a schematic configuration diagram showing an overall configuration of an image forming apparatus according to the present invention. FIG. 3 is a perspective view of a drum unit. These are figures which show an adjustment member, (a) is a top view, (b) is a perspective view. These are side views of the drum unit showing a state before adjusting the gap between the movable bearing and the adjusting member. These are the side views of a drum unit which show the state after the clearance gap adjustment of a movable bearing and an adjustment member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 9 Image forming part 10 Image fixing part 14 Photosensitive drum (image carrier)
14a Rotating shaft 17 Cleaning roller 17a Rotating shaft 30 Drum unit 31 Frame 32 Movable bearings 32a, 32b Circular hole 33 Supporting pin 34 Biasing spring 35 Adjusting member 35a Back side 35b Circular hole 35c Long hole 36, 37 Fixing screw 38 Screw hole

Claims (2)

An image carrier on which a toner image is carried;
A cleaning roller for rubbing the surface of the image bearing member to remove residual toner and the like;
A pair of movable bearings disposed at both ends of the cleaning roller in the rotational axis direction, configured to rotatably support the cleaning roller and configured to move the cleaning roller in a direction away from and contacting the image carrier;
In the image forming apparatus comprising: an urging unit that urges the movable bearing in a direction in which the cleaning roller is brought into contact with the image carrier.
In the vicinity of at least one of the movable bearings, an adjustment member is provided that can restrict the movement of the movable bearing in a direction in which the cleaning roller is brought into contact with the image carrier to a predetermined position. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the adjustment member is formed in an arc shape on a side facing the movable bearing.

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