JP4710370B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus for transferring a toner image formed on an image carrier to a recording medium or an intermediate transfer member to form an image, and more particularly, to a paper attached to the surface of an image carrier after the toner image is transferred. The present invention relates to an image forming apparatus that removes powder, talc, and the like.

  In an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system, a toner image is formed on the surface of an image carrier such as a photoconductor, and this toner image is transferred onto a recording medium by a transfer roll. Toner and fog toner remaining on the surface of the image carrier after transfer are removed by a cleaning device.

  As this cleaning device, for example, a device in which a felt piece is pressed against the surface of an image carrier like a blade has been proposed (see, for example, Patent Document 1).

  However, in this configuration, the felt piece is easily clogged, or is fixed (filming) to the image carrier. Further, there is a problem that foreign matters such as fine talc and paper dust slide through the felt pieces.

  In addition, the cleaning blade is pressed against the surface of the image carrier, and a polishing pad is provided on the downstream side of the cleaning blade (downstream in the moving direction of the image carrier) to remove foreign matters such as talc and paper dust on the surface of the image carrier. An image forming apparatus that has been removed has been proposed (see, for example, Patent Document 2).

However, in this configuration, since the talc and paper dust are removed by polishing or rubbing the surface of the image carrier with a polishing pad, there is a problem that the image carrier is worn and the life is shortened.
JP-A-1-161285 JP-A-1-161279

  The present invention has been made in view of the above problems, and removes talc and paper dust adhering to the surface without polishing the image carrier, thereby enabling image formation that can extend the life of the image carrier. An object is to provide an apparatus.

In order to solve the above problems, an image forming apparatus according to a first aspect of the present invention is an image forming apparatus that forms an image by transferring a toner image on an image carrier to a recording medium or an intermediate transfer member. A pad made of non-woven fabric of fine fibers pressed against the image carrier downstream of the transfer position of the toner image, and a drive for moving the image carrier in the reverse direction when the apparatus is stopped due to the end of image formation And the pad is disposed on a side of the image carrier, the most downstream portion in the process direction is located above the upstream portion in the process direction in the gravitational direction, and the image carrier in the most downstream in the process direction. pressing force is maximized at a contact portion between, are configured to the pressing force decreases gradually from the maximum pressing force at the downstream side contact edge to the minimum pressure on the upstream side contact end, said image bearing Paper dust or tar attached to the body Is accumulated in the most downstream part in the process direction of the pad with the rotation of the image carrier, and the pad moves as the paper dust or the talc moves to the upstream part in the process direction by driving of the driving means. The paper powder or the talc is dropped downward in the direction of gravity by applying a gradually decreasing pressing force to the paper powder or the talc .

  According to the first aspect of the present invention, the pad made of a nonwoven fabric of fine fibers is pressed against the image carrier, and the pressing force at the most downstream contact portion in the process direction is maximized. By pressing the pad against the image carrier, the surface of the image carrier can be entangled and entangled with talc and paper dust without polishing.

In addition, when the apparatus is stopped due to the end of image formation, the image carrier is moved in the reverse direction by the driving means, so that foreign matter such as carrier and toner agglomeration as well as deposits such as paper dust and talc that have been dammed up by the pad are used. In the process of moving the aggregate from the most downstream side of the pad to the upstream side of the pad where the pressing force gradually decreases, the aggregate is loosened by the fine fibers on the pad surface and returned to a semi-aggregated state in which sticking hardly occurs. For this reason, clogging of the pad and adhesion (filming) to the image carrier are unlikely to occur. Further, since the pressing force is maximum at the most downstream portion of the pad, a sufficiently long unwinding step is performed without widening the pad width, and clogging can be effectively prevented.
In addition, the pad is arranged on the side of the image carrier, and the most downstream part in the process direction of the pad is located above the upstream part of the pad in the direction of gravity. Most of the image is peeled off from the pad and the image carrier in the process of moving the image carrier in the reverse direction and falls in the direction of gravity. For this reason, it becomes possible to further reduce clogging of the pad and adhesion to the image carrier.

  With such a configuration, the wear of the image carrier can be reduced, and the life of the image carrier can be extended. In addition, in the case of a direct transfer method in which a large amount of paper dust adheres to the image carrier (a method in which the toner image on the image carrier is directly transferred to paper), a low friction image carrier or a low pressure cleaner is used. Even in this case, it is possible to remove deposits such as paper dust and talc on the surface of the image carrier.

  An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, further comprising a cleaning blade that cleans residual toner on the surface of the image carrier after the transfer of the toner image, and the pad includes The cleaning blade is disposed upstream of the cleaning blade in the process direction.

  According to the second aspect of the present invention, the photoconductor is in a state where the pad surface holds a part of the transfer residual toner or the fog toner by pressing the pad against the image carrier upstream of the cleaning blade in the process direction. Since the surface is rubbed, the effect of removing talc and discharge products is enhanced. Of the residual toner on the surface of the image carrier after transfer, a small amount of final residual toner that has passed through the pad is removed by a cleaning blade on the downstream side in the process direction. As a result, even when a low-friction image carrier or a low-pressure cleaning blade is used, the toner removal performance of the cleaning blade can be improved while effectively removing deposits such as paper dust and talc. It becomes possible.

An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first or second aspect , wherein the pad is made of melamine foam instead of the nonwoven fabric.

According to the third aspect of the invention, pressing the elastic melamine foam against the image carrier facilitates the setting of the pressing force and the configuration of the pad.

An image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to any one of the first to third aspects, wherein the image carrier is a photoconductor subjected to a surface hardening process. It is characterized by being.

According to the invention described in claim 4 , by using a surface-treated photoconductor as the image carrier, the pressing force of the pad is increased or the melamine foam or the like is directly pressed against the image carrier. However, it is possible to further reduce the wear of the image carrier.

An image forming apparatus according to a fifth aspect of the present invention is the image forming apparatus according to any one of the first to fourth aspects, wherein the surface of the image carrier is charged with a DC voltage. It is characterized by having.

According to the fifth aspect of the present invention, when the image carrier is charged by using the contact charger, the image carrier is deteriorated by the discharge in the minute gap and the surface wear easily proceeds, but the AC voltage is superimposed. First, the use of a DC contact charger that can charge the image carrier only with a DC voltage reduces the discharge damage of the image carrier, so that the wear of the image carrier is reduced. Therefore, it is possible to maintain good image quality and operational reliability over a long period of time.

  In the image forming apparatus according to the present invention, it is possible to remove deposits such as talc and paper dust adhering to the surface of the image carrier without strongly rubbing the image carrier, and a reduction in life due to polishing of the image carrier. Can be prevented.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 shows an image forming apparatus 10 according to the first embodiment of the present invention.

  The image forming apparatus 10 is a direct transfer type image forming apparatus in which the toner image formed on the photosensitive drum 12 is directly transferred to the recording paper P. In this image forming apparatus 10, a charging roll 14 for charging the photosensitive drum 12 from the upstream side in the rotation direction around the photosensitive drum 12 rotating in the arrow A direction (process direction), and the charged photosensitive drum. An optical scanning device 16 that forms an electrostatic latent image by irradiating the body drum 12 with a laser beam, and a toner is supplied to the electrostatic latent image forming portion on the photosensitive drum 12 to develop the electrostatic latent image. Thus, a developing device 18 for forming a toner image on the photosensitive drum 12 and a transfer roll 20 disposed so as to face the photosensitive drum 12 across the conveyance path of the recording paper P are arranged. Further, on the downstream side of the transfer roll 20 in the rotation direction (process direction) of the photosensitive drum 12, a pad 22 for removing deposits such as talc and paper dust attached to the photosensitive drum 12, and the photosensitive drum 12. A cleaning device 24 for cleaning residual transfer toner and fog toner on the surface is disposed.

  Further, a conveyance belt 30 stretched by a drive roll 26 and a driven roll 28 is disposed on the upstream side of the transfer roll 20 in the conveyance direction of the recording paper P, and the transfer belt 30 transfers the photosensitive drum 12 to the transfer drum 30. The recording paper P is conveyed between the roll 20.

  Further, a motor 34 is connected to the photosensitive drum 12, and the driving force of the motor 34 is transmitted to rotate the photosensitive drum 12. The rotation of the motor 34 is controlled by the controller 36. As shown in FIG. 2, the controller 36 rotates the photosensitive drum 12 in the direction of arrow A (process direction) during image formation, but reversely rotates the photosensitive drum 12 in the direction of arrow B when the apparatus stops due to the end of image formation. .

  As shown in FIG. 1, the cleaning device 24 includes a rubber cleaning blade 38 that is pressed against the photosensitive drum 12. The cleaning blade 38 is disposed so that the tip thereof faces the upstream side in the process direction (the upstream side in the rotation direction of the arrow A).

  As shown in FIG. 2, the pad 22 has an elastic support 42 made of foamable resin attached to a rigid base material 40, and a non-woven fabric 44 made of ultrafine fibers is attached so as to cover the elastic support 42. . The rigid base 40 is formed with an inclined surface 40A that gradually approaches the photosensitive drum 12 on the downstream side in the process direction (downstream in the rotation direction of the arrow A). The back surface side of the elastic support 42 is cut in accordance with the shape of the inclined surface 40A, and the surface of the elastic support 42 that faces the photosensitive drum 12 is substantially flat. A non-woven fabric 44 mounted so as to cover the elastic support 42 is in contact with the surface of the photosensitive drum 12.

With this configuration of the pad 22, as shown in FIG. 3, the pressing force of the pad 22 to the photosensitive drum 12 becomes maximum at the contact portion with the photosensitive drum 12 at the most downstream in the process direction. The pressing force of the pad 22 decreases almost monotonically from the maximum pressing force at the contact end portion on the downstream side in the process direction to the minimum pressing force at the contact end portion on the upstream side in the process direction. The maximum pressing force at this time is set to 50 gf / cm ² , for example. Further, the maximum pressing force of the pad 22 is smaller than the pressing force of the cleaning blade 38 to the photosensitive drum 12.

  The elastic support 42 is made of, for example, foamable urethane foam. Moreover, the nonwoven fabric 44 is formed, for example with the split fiber. The split fiber is a fiber obtained by splitting one conductive fiber in the thickness direction using a difference in heat shrinkage of each part during heating. By using the split fibers formed by these treatments, it is possible to form the nonwoven fabric 44 made of thin fibers. In the present embodiment, the fineness of the split fibers is 0.3 to 0.7 denier. Examples of the split fiber include polyester / nylon, polyester / polypropylene, polyethylene / polypropylene, and the like.

  The charging roll 14 is disposed so as to come into contact with the photosensitive drum 12, and charges the photosensitive drum 12 by discharging at a minute gap by applying a DC voltage.

  Next, the operation of the image forming apparatus 10 will be described. First, the entire image forming operation will be described, and then the unique action in the present embodiment will be described.

  In the image forming apparatus 10, as shown in FIG. 1, when the photosensitive drum 12 rotates in the process direction (arrow A direction), the surface of the photosensitive drum 12 is first charged to a substantially uniform potential by the charging roll 14. . When the photosensitive drum 12 further rotates, the surface of the photosensitive drum 12 is exposed by the optical scanning device 16, and the potential of the exposed portion of the photosensitive drum 12 is lowered to form an electrostatic latent image. The electrostatic latent image on the photosensitive drum 12 is conveyed to the developing device 18, and toner charged to the same polarity as the charging polarity of the photosensitive drum 12 is electrically attached to the potential lowering portion of the photosensitive drum 12. The electrostatic latent image is developed.

  Thereafter, when the photosensitive drum 12 further rotates, the recording paper P is transported between the transfer roll 20 and the photosensitive drum 12 in accordance with the timing, and a transfer voltage having a polarity opposite to that of the toner is applied to the transfer roll 20 at the same time. Is done. As a result, the toner is electrically attracted to the transfer roll 20 and the toner image on the photosensitive drum 12 is transferred to the recording paper P. The toner image transferred to the recording paper P is heated and pressurized by the fixing device 32 and fixed on the recording paper P.

  In addition, the photosensitive drum 12 after the toner image is transferred moves to the pressing portion of the pad 22 by rotation in the process direction (arrow A direction). The non-woven fabric 44 made of ultrafine fibers is in contact with the photoconductive drum 12, and the surface of the photoconductive drum 12 is not polished and entangled with foreign matters such as talc and paper dust and carriers, etc. Can be stopped. At that time, since the pressing force of the pad 22 is maximum on the most downstream side in the process direction, the adhering matter and the foreign matter are blocked in the vicinity of the downstream end portion of the pad 22. Further, the pressing force of the pad 22 is smaller than the pressing force of the cleaning blade 38, and adhering matters such as talc and paper dust are removed from the surface of the photosensitive drum 12 while the transfer residual toner and the fog toner are held on the photosensitive drum 12. be able to.

  Further, the photosensitive drum 12 moves to the pressing portion of the cleaning blade 38 by rotation in the process direction (arrow A direction). Then, transfer residual toner and fog toner on the surface of the photosensitive drum 12 are removed by the cleaning blade 38 and collected in the cleaning device 24.

  As shown in FIG. 2, when the apparatus is stopped due to the end of image formation, the controller 36 rotates the motor 34 in the reverse direction and rotates the photosensitive drum 12 in the direction opposite to the process direction (arrow B direction). At this time, the distance to rotate the photosensitive drum 12 is set to about 20 mm (substantially the same as the width of the pad 22 in the process direction). As a result, the adhering material such as paper dust and talc, the foreign matter such as the carrier, the toner aggregates, and the like that are blocked by the pad 22 are gradually reduced in the process direction from the most downstream side of the pad 22 in the process direction. In the process of being carried upstream, the nonwoven fabric 44 made of ultrafine fibers is loosened and returned to a semi-aggregated state where sticking is unlikely to occur.

  Further, as shown in FIG. 2, the most downstream part in the process direction of the pad 22 is located above the upstream part in the process direction of the pad 22 in the gravitational direction. In the reverse rotation process, it is peeled off from the pad 22 and the photosensitive drum 12 as it is and dropped in the direction of gravity. For this reason, clogging of the pad 22 and adhesion (filming) to the photosensitive drum 12 are unlikely to occur.

  Further, the pad 22 has the maximum pressing force at the most downstream portion in the process direction, and deposits and foreign substances are blocked in this portion, so that the pad 22 is sufficiently long without increasing the width in the process direction. A process is performed, and clogging and sticking can be effectively prevented.

  In addition, when the contact-type charging roll 14 is used, the photosensitive drum 12 is likely to become brittle due to discharge, but the use of the pad 22 can reduce wear of the photosensitive drum 12. For this reason, the lifetime of the photosensitive drum 12 can be extended. Further, even when the low-friction photosensitive drum 12 or the low-pressure cleaning blade 38 is used, it is possible to remove deposits such as paper dust and talc on the surface of the photosensitive drum 12.

  Next, an image forming apparatus according to a second embodiment of the present invention will be described.

  In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 4, the image forming apparatus 50 corresponds to images of each color of cyan (C), magenta (M), yellow (Y), and black (K), and the photosensitive drums 12C, 12M, 12Y, 12K are arranged in parallel. A motor 34 is connected to each of the photosensitive drums 12C, 12M, 12Y, and 12K, and is driven to rotate in the direction of arrow A (process direction) at a predetermined rotational speed. The rotation of the motor 34 is controlled by the controller 60. In addition, optical scanning devices 16C, 16M, 16Y, and 16K that irradiate laser beams are provided corresponding to the photosensitive drums 12C, 12M, 12Y, and 12K, respectively.

  Here, the periphery of the photosensitive drums 12C, 12M, 12Y, and 12K will be described. In addition, when distinguishing each color of cyan, magenta, yellow, and black, explanation is made by adding C, M, Y, K after the code. However, when it is not necessary to distinguish each color, C, M, Y, and K are omitted.

  On the circumferential surface of the photosensitive drum 12, a charging roll 14, the optical scanning device 16, and a developing device 18 are disposed from the upstream side in the process direction (arrow A direction). Specifically, cyan toner is supplied to the photosensitive drum 12C, magenta toner is supplied to the photosensitive drum 12M, yellow toner is supplied to the photosensitive drum 12Y, and black toner is supplied to the photosensitive drum 12K. , Yellow and black toner images are formed.

  An endless conveyance belt 54 is disposed below each photosensitive drum 12. The conveyor belt 54 is wound around a driving roller 55 and a driven roller 56. A motor 58 is connected to the driving roller 55, and when the driving force of the motor 58 is transmitted and the driving roller 55 rotates, the rotational driving of the driving roller 55 is transmitted to the driven roller 56 via the conveying belt 54 and conveyed. The belt 54 is conveyed in the direction of arrow C.

  The recording paper P is taken out from a paper feeding cassette (not shown) and supplied onto the transport belt 54. The recording paper P supplied on the conveyance belt 54 is guided in the order of the photosensitive drums 12C, 12M, 12Y, and 12K by the conveyance of the conveyance belt 54.

  A transfer roll 20 is disposed at a position facing each photosensitive drum 12 with the conveyance belt 54 interposed therebetween, and a toner image formed on the photosensitive drum 12 on the recording paper P conveyed by the conveyance belt 54. Is transcribed. That is, on the recording paper P, cyan, magenta, yellow, and black toner images are sequentially superimposed and transferred to form a multicolor toner image. The recording paper P onto which the multicolor toner image has been transferred is conveyed to a fixing device (not shown), subjected to a fixing process, and then discharged outside the device.

  Further, a pad 52 is disposed in contact with the photosensitive drum 12 on the downstream side in the rotational direction (downstream in the process direction) of the photosensitive drum 12 relative to the position where the transfer roll 20 is disposed, and further on the downstream side in the rotational direction ( A cleaning device 24 is disposed on the downstream side in the process direction.

  Further, the controller 60 controls the rotation of the motor 34 to rotate the photosensitive drum 12 in the direction of arrow A (process direction) during image formation as shown in FIG. The photosensitive drum 12 is rotated in the reverse direction of the arrow B.

  As shown in FIG. 5, the pad 52 has a superstructure sponge 64 made of melamine foam attached to a rigid base material 62. The rigid base 62 is formed with a curved surface 62A in which the downstream side in the rotation direction of the photosensitive drum 12 (downstream in the process direction) gradually approaches the photosensitive drum 12. Further, the back side of the sponge 64 is cut in accordance with the shape of the curved surface 62A, and the surface side of the sponge 64 facing the photosensitive drum 12 is formed in a substantially flat shape. A nonwoven fabric is not attached to the surface of the pad 52, and the sponge 64 is directly pressed against the photosensitive drum 12.

  The pressing force of the pad 52 is substantially the same as the distribution shown in FIG. 3, and the pressing force becomes maximum at the contact portion with the photosensitive drum 12 on the most downstream side in the process direction, from the downstream side in the process direction to the upstream side in the process direction. The pressing force of is almost monotonously decreasing.

  The photosensitive drum 12 is subjected to surface hardening treatment.

  Next, the operation of the image forming apparatus 50 will be described.

  In this image forming apparatus 50, after the toner images of the respective colors formed on the photosensitive drum 12 are transferred to the recording paper P by the transfer roll 20, the photosensitive drum 12 is rotated in the direction of arrow A (process direction). It moves to the pressing part of the pad 52. The pad 52 is formed by pressing an ultrafine sponge 64 made of melamine foam against the photoconductive drum 12, and adheres to the surface of the photoconductive drum 12 such as talc and paper powder, a carrier, etc. without polishing the surface. Can be caught and dammed up.

  Further, the photosensitive drum 12 is moved to the pressing portion of the cleaning blade 38 by the rotation in the arrow A direction (process direction), and the transfer residual toner and the fog toner on the surface of the photosensitive drum 12 are removed.

  As shown in FIG. 5, when the apparatus is stopped due to the end of image formation, the controller 60 rotates the motor 34 in the reverse direction, and rotates the photosensitive drum 12 in the direction opposite to the process direction (arrow B direction). As a result, the adhering material such as paper dust and talc, the foreign matter such as the carrier, and the toner aggregates that have been blocked by the pad 52 are gradually reduced in the process direction from the most downstream side of the pad 52 in the process direction. In the process of being transported upstream, the sponge 64 is loosened by the ultrafine structure sponge 64 and returned to a semi-aggregated state where sticking hardly occurs. Therefore, clogging of the pad 52 and sticking (filming) to the photosensitive drum 12 hardly occur.

  Further, the pad 52 is easier to rub against the photosensitive drum 12 than the pad 22 of the first embodiment. However, the surface of the photosensitive drum 12 that has been subjected to surface hardening treatment is used to wear the photosensitive drum 12. Can be prevented and the life can be extended.

  In the first and second embodiments, the direct transfer type image forming apparatus transfers the toner image formed on the photosensitive drum onto the recording paper P. However, the present invention is not limited to this configuration. For example, the present invention can be similarly applied to a system in which a toner image on a photosensitive drum is temporarily transferred to an intermediate transfer member and then the toner image on the intermediate transfer member is transferred to a recording sheet.

1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention. 1 is a configuration diagram illustrating a pad used in an image forming apparatus according to a first embodiment of the present invention. 3 is a graph showing a distribution of pressing force of a pad used in the image forming apparatus according to the first embodiment of the present invention to a photosensitive drum. It is a schematic block diagram which shows the image forming apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the pad used with the image forming apparatus which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photosensitive drum (Image carrier)
12C photosensitive drum (image carrier)
12M photosensitive drum (image carrier)
12Y Photosensitive drum (image carrier)
12K photosensitive drum (image carrier)
14 Charging roll (contact charger)
16 Optical scanning device 20 Transfer roll 22 Pad 24 Cleaning device 34 Motor (drive means)
36 Controller 38 Cleaning blade 40A Inclined surface 40 Rigid substrate 42 Elastic support 44 Non-woven fabric 50 Image forming apparatus 52 Pad 58 Motor (drive means)
60 Controller 62 Rigid substrate 62A Curved surface 64 Sponge (melamine foam)
A Process direction B Reverse direction of process P Recording paper (recording medium)

Claims (5)

An image forming apparatus for forming an image by transferring a toner image on an image carrier to a recording medium or an intermediate transfer body,
A pad made of a nonwoven fabric of fine fibers pressed against the image carrier on the downstream side in the process direction from the transfer position of the toner image;
Drive means for moving the image carrier in the reverse direction when the apparatus is stopped due to the end of image formation;
The pad is disposed on the side of the image carrier, and the most downstream portion in the process direction is located above the upstream portion in the process direction in the gravitational direction , and the pressing force is in contact with the image carrier at the most downstream in the process direction. Is configured so that the pressing force gradually decreases from the maximum pressing force at the downstream contact end to the minimum pressing force at the upstream contact end ,
Paper dust or talc adhering to the image carrier is accumulated in the most downstream part in the process direction of the pad as the image carrier rotates.
The pad gives the paper dust or the talc by applying a pressing force that gradually decreases to the paper dust or the talc as the paper dust or the talc moves to the upstream in the process direction by driving of the driving means. An image forming apparatus, wherein the image forming apparatus drops downward in the direction of gravity . A cleaning blade for cleaning residual toner on the surface of the image carrier after transfer of the toner image;
The image forming apparatus according to claim 1, wherein the pad is disposed upstream of the cleaning blade in a process direction. The image forming apparatus according to claim 1 , wherein the pad is made of melamine foam instead of the nonwoven fabric . The image forming apparatus according to claim 1 , wherein the image bearing member is a photoconductor subjected to a surface curing process . The image forming apparatus according to claim 1, further comprising a contact charger that charges the surface of the image carrier with a DC voltage .

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