JP2006276130A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide an image forming apparatus, capable of effectively removing depositions adhered to a cleaning blade using a simple constitution. <P>SOLUTION: The image forming apparatus is provided with an electrostatic latent image carrier 21, having a drum member 21 on the surface of which an electrostatic latent image is formed, and a rotational axis 21s which drives the drum member 21d; an exposure means 23 for irradiating the electrostatic latent image carrier 21 with image light to form the electrostatic latent image; a development means 24 for transferring toner to the electrostatic latent image on the electrostatic latent image carrier 21, to make the electrostatic latent image into a visible image; a transfer means 26 for transferring the toner image, made into the visible image to a recorded medium 28 and a cleaning means 29 fixed so that whose tip contacts the surface of the electrostatic latent image carrier and for cleaning residual toner on the electrostatic latent image carrier, after transfer. The drum member 21d of the electrostatic latent image carrier 21 is formed freely rotatably, and is formed so as to be able to relatively move in the axial direction with respect to the rotational axis 21s at the time of non-image formation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic system or an electrostatic transfer system, such as a copying machine, a printer, a facsimile machine, or a combination of these machines. More specifically, the transfer residual toner on an electrostatic latent image carrier is cleaned. The present invention relates to an image forming apparatus having a cleaning blade.

JP-A-6-282207 JP-A-9-160455 JP-A-6-004014 JP-A-11-24521 JP 2000-112187 A JP 2000-356935 A

  As a cleaning device for an electrostatic latent image carrier (for example, a photosensitive drum) in an image forming apparatus using a conventional electrophotographic method, a cleaning blade capable of obtaining a relatively stable toner removal performance with a low-cost and simple configuration is provided. Widely used. In such a cleaning blade, if paper dust is caught in the blade tip, and deposits such as toner and external additives are deposited, the cleaning performance is significantly deteriorated.

  Furthermore, if the cleaning blade is always opposed to the photosensitive drum at the same position with respect to the axial position of the photosensitive drum, the above-mentioned deposits generated at the tip of the cleaning blade are kept in contact with the same peripheral surface of the drum. It is easy to form streaks on the photosensitive drum.

  In order to cope with such a problem, various cleaning blades have been proposed (see, for example, Patent Documents 1 to 6).

  For example, Patent Document 1 discloses a prior art that removes deposits by applying an impact to the cleaning blade in a state where the photosensitive drum and the cleaning blade are separated from each other.

  Further, Patent Document 2 discloses a prior art in which deposits are removed by applying an impact to the cleaning blade in a state where the photosensitive drum and the cleaning blade are in pressure contact with each other.

  Further, Patent Document 3 discloses a prior art that removes deposits by vibrating a part other than the tip of the cleaning blade with a piezoelectric element.

  Further, Patent Document 4 discloses a prior art in which the photosensitive drum is rotated backward by a certain amount after the forward rotation is stopped to remove the deposits.

  Further, Patent Document 5 discloses a prior art in which the rotation of the photosensitive drum is temporarily stopped for every predetermined number of sheets, and the nip shape between the photosensitive drum and the cleaning member is changed to remove the deposits.

  Furthermore, Patent Document 6 discloses a prior art that removes deposits by sliding the cleaning member in the axial direction.

  These prior arts are intended to remove or prevent the accumulation of aggregates of toner and external additives that grow over time at the nip portion between the photosensitive drum and the cleaning member. Had.

  For example, in the prior art disclosed in Patent Documents 1 to 3, since the deposit is removed by impact / vibration, the generation of impact sound and the reliability of the vibration device become a problem, and the device Problems such as an increase in size and cost have arisen.

  Further, in the prior art disclosed in Patent Document 4, since the aggregates of toner and external additives are fixed to the cleaning blade, it is only necessary to relatively move the photosensitive drum and the cleaning blade in the circumferential direction. There was a problem that the removal effect was insufficient.

  Further, the prior art disclosed in Patent Document 5 has a problem that the configuration is complicated, the apparatus is increased in size and the cost is increased, and the removal effect is insufficient.

  Furthermore, although the prior art disclosed in Patent Document 6 exhibits a good removal effect, the cleaning member holding mechanism is complicated, and problems such as an increase in size and cost of the apparatus have occurred. In particular, when the cleaning blade is configured to be movable so as to be movable, there has been a problem that reliability is lowered due to accumulation of manufacturing tolerance variations. In other words, the complicated holding mechanism for the cleaning member is caused by variations in a predetermined amount of biting and pressing force formed between the cleaning blade and the photosensitive drum that are regulated to have a constant displacement and a constant load. This causes a problem that it is difficult to maintain a stable contact state between the cleaning blade and the photosensitive drum, and a predetermined cleaning performance cannot be maintained. Further, when the cleaning blade is configured to be movable, there are problems that the number of replacement parts increases, the replacement work becomes complicated, and the running cost increases.

  SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, it is an object of the present invention to provide an image forming apparatus that can effectively remove deposits adhered to a cleaning blade at a low cost with a simple configuration. And

  In order to achieve the above object, an image forming apparatus according to the present invention includes a drum member on which an electrostatic latent image is formed, an electrostatic latent image carrier having a rotation shaft that drives the drum member, An exposure unit that irradiates the electrostatic latent image carrier with image light to form an electrostatic latent image, and a developing unit that transfers toner to the electrostatic latent image on the electrostatic latent image carrier to make it visible. And a transfer means for transferring the visualized toner image to the recording medium, and an electrostatic latent image carrier after the transfer, which is fixed so that the tip thereof is in contact with the surface of the electrostatic latent image carrier. Cleaning means for cleaning residual toner on the body, and the drum member of the latent electrostatic image bearing member is formed to be rotatable, and is relatively moved in the axial direction with respect to the rotation shaft during non-image formation. It is characterized by being formed.

  The image forming apparatus of the present invention configured as described above includes an electrostatic latent image carrier, an exposure unit, a developing unit, a transfer unit, and a cleaning unit. Since it is formed so as to be rotatable and is relatively movable in the axial direction with respect to the rotation axis during non-image formation, the cleaning blade and the electrostatic latent image are not provided with any moving mechanism in the cleaning means. It is possible to provide an image forming apparatus that can maintain a stable contact state with the carrier and can effectively remove the agglomerated toner and the like fixed to the tip of the cleaning blade at a low cost with a simple configuration.

  Further, the drum member of the electrostatic latent image carrier may rotate in the opposite direction to that during image formation during non-image formation.

  In such a configuration, the drum member of the electrostatic latent image carrier rotates in the opposite direction to that at the time of image formation during non-image formation, and thus is disposed on the downstream side in the rotation direction of the drum member at the time of image formation. It is possible to prevent contamination due to adhesion of residual toner or the like on the charging means. In addition, since the waste toner collection unit for preventing toner adhesion is usually provided for the transfer means disposed on the upstream side, the front end of the cleaning blade is configured by the above-described configuration. It is possible to prevent the peripheral device from being contaminated by the agglomerated toner or the like removed from the peripheral device.

  Further, the drive source for rotating the rotating shaft of the electrostatic latent image carrier may also serve as the drive source for moving the drum member of the electrostatic latent image carrier in the axial direction.

  In such a configuration, the drive source for rotating the rotating shaft of the electrostatic latent image carrier also serves as the drive source for moving the drum member of the electrostatic latent image carrier in the axial direction. And an image forming apparatus capable of contributing to cost reduction can be realized.

  Further, the drum member of the electrostatic latent image carrier may be arbitrarily movable in the axial direction regardless of the rotation state of the rotation shaft.

  In this case, the drum member of the electrostatic latent image carrier can be arbitrarily moved in the axial direction regardless of the rotation state of the rotary shaft. Can be performed independently of the rotational state of the rotary shaft. As a result, when the electrostatic latent image carrier is moved in the axial direction, a rapid cleaning mode is performed at any timing that does not affect image formation without stopping or restarting the electrostatic latent image carrier. Is possible.

  According to the present invention, it is possible to realize an image forming apparatus that can effectively remove toner, external additives, and the like adhered to the cleaning blade at a low cost with a simple configuration.

<First embodiment>

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a schematic configuration of an image forming apparatus including a developing device according to the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention.

  As shown in FIG. 1, an image forming apparatus 10 according to the present invention is an electrostatic latent image carrier that forms a latent image due to a difference in electrostatic potential on a surface by irradiating image light after uniform charging. A photosensitive drum 21 is provided, and a charging device 22 for uniformly charging the surface of the photosensitive drum 21 around the photosensitive drum 21 and an exposure for irradiating the photosensitive drum 21 with image light to form a latent image on the surface. A photosensitive drum 21 that faces the photosensitive drum 21 with a recording medium 28 interposed therebetween, and a developing device 24 that selectively transfers toner to a latent image on the photosensitive drum 21 to form a toner image. A transfer roll 26 that generates a transfer bias electric field and a cleaning device 29 that removes toner remaining on the photosensitive drum 21 after the transfer of the toner image are provided. The recording medium 28 is supplied from the upstream side of the facing portion (nip portion) between the photosensitive drum 21 and the transfer roll 26, and the unfixed image transferred onto the recording medium 28 is downstream. A fixing device 50 is provided that heats and melts the toner image and presses the toner image onto the recording medium 28.

  Here, the photosensitive drum 21 can be formed by forming a photosensitive layer made of an organic photosensitive material, an amorphous selenium photosensitive material, an amorphous silicon photosensitive material, or the like on the surface of a metal drum rotating in the direction of the arrow. .

  The charging device 22 uses, for example, a scorotron in which a high voltage is applied to a thin wire made of tungsten or the like, and a shield made of aluminum or the like spaced apart from the thin wire and a grid electrode having a gap on the photosensitive drum 21 side are arranged. it can.

  The exposure device 23 includes a laser writing device and an LED array, generates exposure light that blinks based on an image signal, and scans this in the main scanning direction of the photosensitive drum 21 by a polygon mirror. An electrostatic latent image is formed on the surface of the photosensitive drum 21. This electrostatic latent image is formed as a potential image by contrast with a high potential portion not exposed to light because the surface potential of the photosensitive drum 21 in the portion exposed to light is lowered.

  In addition, the developing device 24 accommodates a two-component developer composed of toner and magnetic carriers that are colored particles in a housing, supports the two-component developer on the developer carrier 24R, and biases the developer carrier 24R. By applying a developing bias from the power source 25, the developer carrier 24R is held at an intermediate potential between the high potential portion and the low potential portion of the electrostatic latent image, and the image portion of the electrostatic latent image is charged. The image is developed with

  The transfer device 26 is composed of, for example, a transfer roll disposed in contact with the photoconductive drum 21, and a transfer bias in a direction in which a toner image on the photoconductive drum 21 is attracted by a bias power source 27 is applied to the photoconductive body. The toner image on the drum 21 is transferred to the recording medium 28.

  Further, the fixing device 50 is, for example, a heat roll type, and includes a heating roll 51 and a pressure roll 52, and the recording medium 28 is passed between the heating roll 51 and the pressure roll 52, thereby toner. The image is fixed on the recording medium 28.

  Further, in the present embodiment, the toner remaining on the photosensitive drum 21 is configured to be removed by a blade type cleaning device 29. This blade-type cleaning device 29 is provided with a cleaning blade 31 extending in the axial direction of the photosensitive drum 21 at the tip of a support member 30 having a substantially L-shaped cross section. It is fixedly installed in the housing of the device. The tip of the cleaning blade 31 is formed so as to contact the surface of the photosensitive drum 21 with a predetermined pressing force and biting amount.

  Further, a waste toner collection container 35 for storing the transfer residual toner collected by the cleaning device 29 is arranged on the upstream side of the cleaning device 29 in the rotation direction of the photosensitive drum 21 (below the cleaning blade 31 in the figure). It is installed.

  Next, the drive mechanism of the photosensitive drum 21 of the image forming apparatus according to the present invention will be described with reference to FIG.

  As shown in FIG. 2, the photosensitive drum 21 according to the present invention includes a rotating shaft 21s and a hollow cylindrical drum member 21d, and is formed in a spiral shape on one end side in the axial direction of the rotating shaft 21s. The gear portion 21g is formed, and the drive gear Gw is disposed so as to mesh with the gear portion 21g. The drum member 21d and the rotation shaft 21s are coupled in the rotation direction by, for example, a key, and the drive gear Gw is rotationally driven by a drive source (not shown) connected to one end of the rotation shaft Gs of the drive gear Gw. As a result, the drum member 21d of the photosensitive drum 21 is rotationally driven via the gear portion 21g of the rotating shaft 21s.

  In addition, the drum member 21d is supported by, for example, a thrust bearing Bs with respect to the rotation shaft 21s, whereby the drum member 21d is formed so as to be rotatable, and in the axial direction with respect to the rotation shaft 21s. Is configured to be movable.

Further, the axial ends of the drum member 21d, a stopper S _L and S _R to restrict the amount of axial movement of the drum member 21d within a predetermined range is disposed, respectively.

  In the present embodiment, the engagement between the drive gear Gw and the gear portion 21g is formed so as to be in the meshing relationship of a helical gear (helical gear), so that the drive gear Gw is in the direction of the arrow CCW (for example, When rotated in the counterclockwise direction), the gear portion 21g of the rotating shaft 21s rotates in the arrow CW direction (for example, clockwise direction), and the rotating shaft 21s rotates in the arrow CW direction.

  At this time, a thrust in the axial direction is generated simultaneously with the rotational force in the drum member 21d, and the drum member 21d is caused to move in the axial direction along with the rotation of the rotational shaft 21s by this axial thrust. It moves gradually.

  Further, the image forming apparatus 10 according to the present embodiment includes an image forming mode in which normal image formation is performed and a cleaning mode in which deposits on the tip of the cleaning blade 31 of the cleaning device 29 are removed during non-image formation. In the mode and the non-image-forming cleaning mode, the rotation shaft 21s of the photosensitive drum 21 is driven to rotate in the opposite direction.

  Hereinafter, the operation of the photosensitive drum 21 in each mode will be described with reference to FIG.

First, in the normal image forming mode, as shown in FIG. 3A, the rotation shaft 21s of the photosensitive drum 21 rotates (forward rotation) in a predetermined direction via the gear portion 21g, and the photosensitive drum 21 The drum member 21d of the body drum 21 rotates in the forward direction and moves in the axial direction (for example, in this example, from right to left in the figure) by the axial propulsive force F ₁ along the arrow direction. The movement in the axial direction is restricted by the stopper S _L , and only the rotational movement is performed at the position, and normal image formation is performed. Note that a bearing (not shown) is disposed on the surface of the stopper S _L facing the drum member 21d, and is configured so as not to hinder smooth rotational movement of the drum member 21d at a predetermined image forming position. Yes.

On the other hand, in the non-image-type cleaning mode, as shown in FIG. 3B, the rotating shaft 21s of the photosensitive drum 21 rotates (reverses) in the direction opposite to the normal rotation direction via the gear portion 21g. The drum member 21d of the photosensitive drum 21 also rotates in the reverse direction, and, for example, a predetermined rotational position (in this example, a stopper S in the image formation) by the axial thrust F ₂ along the arrow direction. the axial (eg this example from the contact position) with _L, wherein, after moving a predetermined distance ΔL to right) from the left, the stopper S _R, is restricted a movement in the axial direction. Note that a bearing (not shown) is disposed on the surface of the stopper S _R facing the drum member 21d, as in the case of the stopper S _L , so that the smooth rotation of the drum member 21d is not hindered. . By such movement of the drum member 21d in the axial direction, the tip of the cleaning blade 31 is brought into sliding contact, and the adhered matter fixed to the tip is removed.

  In the photosensitive drum 21 according to the present embodiment configured as described above, the cleaning device 29 is not provided with a complicated holding mechanism or moving mechanism, so that the cleaning blade 31 and the photosensitive drum 21 are stably in contact with each other. The state can be maintained. Further, by rotating the drum member 21d in the axial direction with respect to the tip of the cleaning blade 31 to which the adhering matter adheres, it is possible to effectively and reliably remove the aggregated toner and the like at the tip of the cleaning blade 31. At the same time, the state where the adhering matter fixed to the tip of the cleaning blade 31 is kept in contact with the same peripheral surface of the drum member 21d is eliminated, and generation of streak-like scratches on the peripheral surface of the drum member 21d is suppressed. be able to.

  Furthermore, since the drive source for moving the drum member 21d of the photosensitive drum 21 in the axial direction also serves as a rotational drive source, it contributes to downsizing and cost reduction of the apparatus without providing a new drive source. can do.

  Furthermore, in the cleaning mode, the drum member 21d of the photosensitive drum 21 is rotated in the opposite direction to that during image formation, so that the aggregated toner or the like removed from the tip of the cleaning blade 31 is disposed downstream in the rotation direction. The waste toner is collected by the waste toner collecting container 35, and the peripheral device can be prevented from being contaminated by the toner.

In the cleaning mode during non-image formation, the drum member 21d may be reciprocated between the stoppers S _L and S _R by appropriately reversing the rotation direction of the rotation shaft 21s. However, the movement in the axial direction is also possible. If the stroke ΔL is about 0.5 mm to 3 mm, it has been confirmed that the deposit on the tip of the cleaning blade 31 can be sufficiently removed by a single axial movement.
<Second Embodiment>

  Next, a second embodiment of the photosensitive drum according to the present invention will be described with reference to FIG.

  The photosensitive drum 21A according to the present embodiment is configured such that the drum member 21d can move independently in the axial direction regardless of the rotation direction of the rotation shaft 21s, and is the same as in the previous embodiment. The members having such functions are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 4, the photosensitive drum 21A according to the present embodiment includes a rotating shaft 21s having a key portion 21k and a hollow cylindrical drum member 21d. The drum member 21d and the rotating shaft 21s are The flange members 21f functioning as bearings are formed to be movable relative to each other in the axial direction. The drum member 21d is fitted to the rotating shaft 21s by a bearing member 21b formed integrally with a flange member 21f at one end and formed with a key groove, and is rotated by a driving source 21m connected to one end of the rotating shaft 21s. Driven freely.

Further, an abutting member P _L that abuts on the axial side surface 21 _L of the drum member 21d on the drive source 21m side via the bearing B and is movable in the axial direction is provided on the axial side surface 21 _L. Are arranged opposite to each other. On the outer peripheral side of the contact member P _L (in the case of this example, two places in the upper and lower parts in the figure), there is a cam member C that allows the drum member 21d of the photosensitive drum 21A to move in the axial direction. Further, it is arranged. The cam member C is the drive source 21m of the rotation shaft 21s is connected to a drive source independent not shown, and is rotatably formed in the rotation center C ₀ around.

On the other hand, at the axial end of the photosensitive drum 21A opposite to the drive source 21m, the movement of the drum member 21d in the axial direction is blocked by a predetermined movement amount (for example, about 0.5 to 3.0 mm). regulating member P _R for are disposed. The regulating member P _R is, for example, is opposite axial side surface 21 _R disposed facing the axial side surface 21 _L, a plate-shaped plate member 211 which is fixed to the frame, the plate member 211 and the axial side surface is disposed through the compression spring S between the 21 _R, by the compression spring S, and a constantly axial side 21 is biased so as to contact the _R and the contact member 213.

  In the photosensitive drum 21A according to the present embodiment configured as described above, the cam member C is driven by a driving source (not shown) independently of the rotation of the rotating shaft 21s, whereby the rotating shaft 21s of the photosensitive drum 21A is driven. Regardless of the rotation direction and rotation state, the drum member 21d of the photosensitive drum 21A can be moved in the axial direction. A specific operation will be described below.

First, when in the state shown in Figure 4, by the biasing force of the compression springs S of the regulating member P _R, the drum member 21d of the photosensitive drum 21A is in the figure, axially left side (drive source 21m side) Maximum displacement. From this state, when the cam member C is rotated 90 degrees around the rotation center C ₀ by a drive source (not shown), the drum member 21d is moved to the right in the axial direction in the drawing via the contact member P _L and the bearing B. maximum displacement, further, the cam member C is rotated 90 degrees from this state, the return to the state illustrated by the urging force of the compression spring S of the regulating member P _R, in the figure, the maximum displacement in the axial direction left It is configured as follows. That is, the drum member 21d of the photosensitive drum 21A is configured to be movable within a predetermined stroke range in the axial direction according to the rotation angle of the cam member C regardless of the rotation direction of the rotation shaft 21s. Yes.

  As in the present embodiment, by configuring the drum member 21d of the photosensitive drum 21A to be movable in the axial direction regardless of the rotation of the photosensitive drum 21A, similarly to the previous embodiment, the cleaning device 29 is configured. Therefore, a stable contact state between the cleaning blade 31 and the photosensitive drum 21 can be maintained, and the tip of the cleaning blade 31 to which the adhered matter adheres can be maintained. Thus, by rotating the drum member 21d in the axial direction while rotating, the aggregated toner and the like at the tip of the cleaning blade 31 can be effectively and reliably removed. Further, as compared with the previous embodiment, the rotation direction of the photosensitive drum 21A is reversed when shifting from the normal image forming mode to the cleaning mode for removing the deposit adhered to the tip of the cleaning blade. There is no need. That is, there is no loss due to the start and stop such as once stopping the photosensitive drum 21A and then restarting it so as to rotate in a predetermined direction, thereby enabling a rapid cleaning mode at any timing that does not affect image formation. Implementation becomes possible.

  In addition, since the drum member 21d can be driven to rotate at an arbitrary position in the axial direction, by appropriately changing the rotation position of the drum member 21d, the adhered matter fixed to the tip of the cleaning blade 31 is attached to the drum member 21d. It is possible to easily avoid the state of being kept in contact with the same peripheral surface, and it is possible to more effectively suppress the occurrence of streak-like scratches on the surface of the drum member 21d.

  Although the cam member C is used as the axial movement means in the present embodiment, a worm gear or a laminated piezoelectric element laminated in the axial direction may be used instead of the cam member C.

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a schematic diagram illustrating a configuration of a driving unit of the photosensitive drum according to the first embodiment of the present invention. FIG. 3 is a schematic diagram showing the operation of the photosensitive drum according to the first embodiment of the present invention. It is a schematic diagram which shows the structure of the drive part of the photosensitive drum which concerns on 2nd embodiment of this invention.

Explanation of symbols

10: image forming apparatus, 21, 21A: photosensitive drum, 21d: drum member, 21g: gear portion, 21s: rotating shaft, 21m: drive source, 22: charging device, 23: exposure device, 24: developing device, 24R : Developer carrier 25: bias power source 26: transfer device 27: bias power source 28: recording medium 29: cleaning device 30: support member 31: cleaning blade 35: waste toner collecting container 50 : fixing device 51: heating roll, 52: a pressure roll, 211: plate member, 213: contact member, C: cam member, Gs: rotary shaft, Gw: driving gear, P _L: contact member, P _R : Restriction member, S: compression spring, S _L , S _R : stopper, ΔL: movement stroke

Claims (4)

An electrostatic latent image carrier having a drum member on which an electrostatic latent image is formed, and a rotation shaft for driving the drum member;
Exposure means for irradiating the electrostatic latent image carrier with image light to form an electrostatic latent image;
Developing means for transferring the toner to the electrostatic latent image on the electrostatic latent image carrier to visualize it;
Transfer means for transferring a visualized toner image to a recording medium;
A cleaning means for cleaning the residual toner on the electrostatic latent image carrier after transfer, the tip of which is fixed so as to be in contact with the surface of the electrostatic latent image carrier,
The drum member of the latent electrostatic image bearing member is formed so as to be rotatable, and is formed so as to be relatively movable in the axial direction with respect to the rotation shaft during non-image formation. .   The image forming apparatus according to claim 1, wherein the drum member of the electrostatic latent image carrier rotates in a direction opposite to that during image formation during non-image formation.   3. The drive source for rotating the rotation shaft of the electrostatic latent image carrier also serves as a drive source for moving the drum member of the electrostatic latent image carrier in the axial direction. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the drum member of the electrostatic latent image carrier is arbitrarily movable in the axial direction regardless of a rotation state of the rotation shaft.

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