JP2015025931A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus including a cleaning device configured to prevent a foreign matter from being caught in a contact part between a photoreceptor drum and a blade, while preventing abrasion of a photoreceptor.SOLUTION: A printer includes: a photoreceptor drum 10 on which a toner image is formed; a cleaning blade for cleaning the photoreceptor drum 10 after the toner image is transferred; and a brush roller 34 which comes in rotating contact with a contact part between the cleaning blade and the photoreceptor drum 10. The photoreceptor drum 10 rotates around a support shaft 10a, and periodically reciprocates in an axial direction of the support shaft 10a. The brush roller 34 rotates around a support shaft 34a, and periodically reciprocates in the axial direction of the support shaft 34a. The photoreceptor drum 10 and the brush roller 34 move back and forth in opposite directions at different periods.

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus including a cleaning device that removes toner remaining on the surface of a photosensitive drum.

  The electrophotographic image forming apparatus is provided with a cleaning device that removes toner remaining on the surface of the photosensitive drum after transferring the toner. In a general cleaning device, a cleaning blade made of urethane rubber or the like is brought into contact with the surface of the photoreceptor to scrape remaining toner. However, in this method, foreign matters such as paper dust and toner aggregates may be caught in the contact portion between the blade and the photosensitive drum. If the photoconductor is driven to rotate in this state as it is, there is a possibility that circumferential streaks on the surface of the photoconductor occur due to foreign matter, resulting in an image defect.

  Therefore, a brush roller is installed on the upstream side of the cleaning blade, and the brush roller is rotated and brought into contact with the tip of the blade to remove the foreign matter present at the contact portion between the blade and the photosensitive drum. Proposals for preventing pinching have been proposed (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2-110489

  However, the above-described conventional technique is effective against foreign matters that are formed over time in a cleaning device such as toner aggregates, but it continuously enters the cleaning device, and the toner A high effect cannot be expected for paper dust larger than the aggregate.

  Further, when the foreign matter present at the tip of the blade is removed by the brush roller, the brush roller naturally comes into contact with the photosensitive member. In order to reliably remove paper dust and the like, it is necessary to increase the pressure contact force of the brush by hardening the brush. In this case, the surface of the photoconductor may be scraped and the life of the photoconductor may be shortened. For this reason, the brush which has the press-contact force of the grade which can remove paper dust completely cannot be used. When the brush is softened, the brush does not uniformly contact the surface of the photosensitive member, and there are positions where the brush strikes and does not strike, and a good effect cannot be obtained.

  On the other hand, there is a method of reciprocating in the axial direction while rotating the photosensitive member. The paper powder is caught in the contact part when the paper powder stays in one position in the contact part. By moving the photosensitive member in the axial direction, the time during which the paper dust stays in one place can be shortened, and the probability that pinching will occur is reduced. However, in order to obtain a reliable effect, it is necessary to increase the moving distance of the photosensitive member, and in this case, there is a concern that problems such as image distortion may occur. Although it is conceivable to move the blade instead of the photosensitive member in the axial direction of the photosensitive member, in this case, there is a problem that the toner leaks from the end of the blade or the mechanism becomes complicated.

  Therefore, in consideration of the above circumstances, the present invention suppresses the abrasion of the photoconductor so that the life of the photoconductor can be achieved in the cleaning device provided in the image forming apparatus, and also distorts the image and makes the mechanism complicated. An object is to prevent foreign matter from being caught in the contact portion between the photosensitive drum and the blade without causing a problem.

  An image forming apparatus according to the present invention includes a photosensitive drum that rotates around a support shaft to form a toner image, a cleaning blade that cleans the photosensitive drum after the toner image is transferred, and a support shaft. A brush roller that rotates and contacts a contact portion between the cleaning blade and the photosensitive drum while rotating, and the photosensitive drum reciprocates in the axial direction of the support shaft; The brush roller reciprocates in the axial direction of the support shaft, and the cycle or direction of the reciprocating movement of the photosensitive drum and the reciprocating movement of the brush roller are different.

  By adopting such a configuration, it is possible to reduce the time that foreign matter stays in one place, making it difficult to pinch foreign matter, and even if a brush with low rigidity and softness is used, the tip of the brush can be used as a cleaning blade. Since it can be applied evenly to the contact portion with the photosensitive drum, foreign matter can be reliably removed.

  In the image forming apparatus of the present invention, it is preferable that the one-way moving distance when the photosensitive drum makes one reciprocation is in a range of 0.1 mm to 0.3 mm.

  By adopting such a configuration, it is possible to exhibit the effect of suppressing the retention of foreign matters while suppressing the occurrence of image defects such as image distortion.

  In the image forming apparatus of the present invention, the one-way movement distance when the brush roller makes one reciprocation may be longer than the one-way movement distance when the photosensitive drum makes one reciprocation.

  By adopting such a configuration, the brush roller can be applied uniformly to the contact portion.

  In the image forming apparatus of the present invention, a distance obtained by adding a one-way movement distance when the brush roller makes one reciprocation and a one-way movement distance when the photosensitive drum makes one reciprocation is 0.5 mm or more. Is preferred.

  By adopting such a configuration, the brush roller can be uniformly applied to the contact portion while suppressing the occurrence of image distortion or the like due to the axial movement of the photosensitive drum, and a sufficient foreign matter removing effect can be exhibited.

  As is apparent from the above description, according to the present invention, it is possible to apply the brush uniformly to the contact portion after making it difficult for foreign matter to stay in the contact portion between the cleaning blade and the photosensitive drum. Even if a soft brush is used, foreign matters can be reliably removed.

1 is a schematic diagram illustrating an outline of a printer according to an embodiment of the present invention. 1 is a side sectional view showing a printer cleaning device according to an embodiment of the present invention. FIG. 3 is a plan view illustrating an example of a moving mechanism in the axial direction of the photosensitive drum and the brush roller of the printer according to the embodiment of the invention.

  First, the overall configuration of a color printer 1 as an image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic diagram showing an outline of a configuration of a color printer according to an embodiment of the present invention.

  The color printer 1 includes a box-shaped printer main body 2. A paper feed cassette 3 that stores paper (not shown) is provided at a lower portion of the printer main body 2. A tray 4 is provided.

  An intermediate transfer belt 5 is installed between a plurality of rollers on the upper part of the printer body 2, and an exposure unit 6 including a laser scanning unit (LSU) is disposed below the intermediate transfer belt 5. . A plurality of image forming units 7 are provided below the intermediate transfer belt 5. Each image forming unit 7 is provided corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K), for example. In each image forming unit 7, a photosensitive drum 10 is supported by a support shaft 10a so as to be rotatable and movable in the axial direction of the support shaft 10a. As the photoconductor drum 10, a photoconductor made of a-Si (amorphous silicon) or an organic photoconductor (OPC) can be used. Around the photosensitive drum 10, a charger 11, a developing device 12, a primary transfer unit 13, a cleaning device 14, and a static eliminator 15 are rotated in the rotational direction of the photosensitive drum 10 (see the arrow in FIG. 1). Are arranged along. A developer container 16 is provided above each developing device 12.

  A paper transport path 20 is provided on one side of the printer main body 2 (on the right side in the drawing). A paper feed unit 21 is provided at the upstream end of the conveyance path 20, and a secondary transfer unit 22 is provided at the other end (right end in the drawing) of the intermediate transfer belt 5 at a middle portion of the conveyance path 20. A fixing unit 23 is provided on the downstream side, and a paper discharge port 24 is provided on the downstream end of the transport path 20.

  Next, an image forming operation of the color printer 1 having such a configuration will be described.

  When the color printer 1 is turned on, various parameters are initialized, and initial settings such as temperature setting of the fixing unit 23 are executed. When image data is input from a computer or the like connected to the color printer 1 and an instruction to start printing is given, an image forming operation is executed as follows.

  First, after the surface of the photoconductor drum 10 is charged by the charger 11, the photoconductor drum 10 is exposed according to the image data by the laser light (see arrow P) from the exposure device 6, and the photoconductor. An electrostatic latent image is formed on the surface of the drum 10. The electrostatic latent image is developed into a toner image of a corresponding color by the developing device 12. This toner image is primarily transferred to the surface of the intermediate transfer belt 5 at the primary transfer portion 13. Each image forming section 7 sequentially repeats the above operation, whereby a full-color toner image is formed on the intermediate transfer belt 5. The toner remaining on the photosensitive drum 10 is removed by the cleaning device 14, and the residual charge is removed by the charge remover 15.

  On the other hand, the paper taken out from the paper feed cassette 3 or the hand tray (not shown) by the paper feed unit 21 is conveyed to the secondary transfer unit 22 in synchronism with the above-described image forming operation, and is subjected to secondary transfer. In the portion 22, the full color toner image on the intermediate transfer belt 5 is secondarily transferred to the paper. The sheet on which the toner image has been secondarily transferred is conveyed downstream in the conveyance path 20 and enters the fixing unit 23 where the toner image is fixed on the sheet. The sheet on which the toner image is fixed is discharged from the sheet discharge outlet 24 to the sheet discharge tray 4.

Next, the cleaning device 14 will be described with reference to FIG.
The cleaning device 14 includes a box-shaped frame member 32, a cleaning blade 33 and a brush roller 34 supported by the frame member 32, and a collection spiral 35 accommodated in the frame member 32.

  The cleaning blade 33 is a long plate-like member having a thickness of about 2 mm and a rectangular cross section, and is made of, for example, urethane resin. The cleaning blade 33 is arranged in the longitudinal direction of the photosensitive drum 10 so that one edge is in contact with the surface of the photosensitive drum 10.

The brush roller 34 is formed by radially implanting resin fibers such as nylon on the surface of a shaft member made of metal or the like. As an example, the fineness of the fiber is 2 to 10 dtex, the density is 40 to 300 kF / inch ² , and the length is 1 to 5 mm. The brush roller 34 rotates in the forward direction with respect to the photosensitive drum 10 around a supporting shaft 34a substantially parallel to the supporting shaft 10a of the photosensitive drum 10, and is supported so as to be movable in the axial direction of the supporting shaft 34a. ing. The brush roller 34 is disposed substantially parallel to the blade 33 such that the tip thereof contacts the contact portion between the photosensitive drum 10 and the blade 33 from the upstream side of the cleaning blade 33.

  The collection spiral 35 is arranged in the longitudinal direction of the photosensitive drum 10 and is connected to a toner collection box (not shown) provided outside the cleaning device 14. The collection spiral 35 collects the toner removed from the surface of the photosensitive drum 10 by the cleaning blade 33 and conveys it to the toner collection box.

  In the color printer 1 of the present invention, the photosensitive drum 10 and the brush roller 34 reciprocate in the axial direction at different periods. Alternatively, in the case of the same cycle, the reciprocation is performed in the opposite direction. Here, the period refers to the time required for the photosensitive drum 10 or the brush roller 34 to reciprocate once.

With reference to FIG. 3, an example of a mechanism for reciprocally moving the photosensitive drum 10 and the brush roller 34 in the axial direction at different periods will be described.
The moving mechanism of the photosensitive drum 10 includes a gear member 51, a cam member 53, and an urging member 57. As described above, the photosensitive drum 10 is supported on the support shaft 10a fixed in the apparatus so as to be rotatable about the coaxial 10a.

  The gear member 51 is a ring-shaped member, and includes a gear portion 51a formed on the outer peripheral surface and a cam follower 51b formed on one side surface (right side surface in the drawing). The gear member 51 is fixed to one end face (right end in the drawing) of the photosensitive drum 10 so as to be coaxial with the support shaft 10a of the photosensitive drum 10 so that the cam follower 51b faces outward. The gear portion 51a of the gear member 51 meshes with a drive gear 55 that is rotationally driven by a motor or the like (not shown).

  The cam member 53 is a ring-shaped member, and has a cam surface 53b that abuts on the cam follower 51b of the gear member 51 on one side surface (left side surface in the figure). The cam surface 53b is formed so that the height in the axial direction differs in the circumferential direction. The cam member 53 is fixed to one end portion (right end in the figure) of the support shaft 10a of the photosensitive drum 10 so as to be coaxial with the support shaft 10a and with the cam surface 53b facing inward.

  The urging member 57 is a coil spring that urges the photosensitive drum 10 toward the cam member 53 in the axial direction (right direction in the drawing). By this urging member 57, the cam follower 51 b of the gear member 51 is pressed against the cam surface 53 b of the cam member 53.

  When the drive gear 55 is driven to rotate, the gear member 51 that meshes with the drive gear 55 rotates about the support shaft 10a of the photosensitive drum 10, and the photosensitive drum 10 to which the gear member 51 is fixed rotates. When the gear member 51 rotates, the cam follower 51 b of the member 51 moves along the cam surface 53 b of the cam member 53. Since the cam surface 53b is formed to have a different axial height in the circumferential direction, the cam follower 51b that moves along the cam surface 53b, that is, the photosensitive drum 10 to which the gear member 51 is fixed is provided. It is urged by the urging member 57 or reciprocates in the axial direction along the support shaft 10a against the urging force. The height of the cam surface 53b and the cam follower 51b is set so that the one-way moving distance X1 when the photosensitive drum 10 reciprocates is in the range of 0.1 mm to 0.3 mm. The cam surface 53b and the cam follower 51b are formed so that the number of reciprocating movements during one rotation is a predetermined number (for example, one reciprocation per rotation).

  The moving mechanism of the brush roller 34 can be configured to have a gear member 61, a cam member 63, and an urging member 67 similar to the moving mechanism of the photosensitive drum 10. In this case, the brush roller 34 has a structure including a support shaft 34a fixed in the apparatus, an outer cylinder 34b rotatable around the support shaft 34a, and a brush 34c implanted on the outer peripheral surface of the outer cylinder 34b. And

  The gear member 61 includes a gear portion 61a formed on the outer peripheral surface and a cam follower 61b formed on one side surface (the right side surface in the figure). The gear member 61 is fixed to one end surface (right end in the drawing) of the outer cylinder 34b of the brush roller 34 so as to be coaxial with the support shaft 34a so that the cam follower 61b faces outward. The number of teeth of the gear portion 61 a of the gear member 61 is different from the number of teeth of the gear portion 51 a of the gear member 51 fixed to the end surface of the photosensitive drum 10. In this example, the number of teeth of the gear member 61 of the brush roller 34 is smaller than the number of teeth of the gear member 51 of the photosensitive drum 10. The gear member 61 is engaged with a gear portion 51 a of the gear member 51 fixed to the end surface of the photosensitive drum 10.

  The cam member 63 has a cam surface 63a formed on one side surface (the left side surface in the figure), and the cam surface is coaxial with the support shaft 34a at one end portion (the right end in the figure) of the support shaft 34a. 63a is fixed so as to face inward.

  The urging member 67 is a coil spring that urges the outer cylinder 34 b toward the cam member 63 in the axial direction (right direction in the drawing), and presses the cam follower 61 b of the gear member 61 against the cam surface 63 a of the cam member 63. ing.

  When the gear member 51 of the photosensitive drum 10 is driven and rotated by the driving gear 55, the gear member 61 of the brush roller 34 that meshes with the gear member 51 of the photosensitive drum 10 rotates about the support shaft 34a, and the gear member 61 rotates. The fixed outer cylinder 34b rotates in the opposite direction to the photosensitive drum 10. That is, the brush roller 34 rotates in the forward direction with respect to the rotation of the photosensitive drum 10. At the same time, the cam follower 61b of the gear member 61 moves along the cam surface 63a of the cam member 63, and the outer cylinder 34b is urged by the urging member 57 or against the urging force against the support shaft 34a. Reciprocate along the axis. The one-way movement distance X2 when the outer cylinder 34b reciprocates is longer than the one-way movement distance X1 of the photosensitive drum 10, and the one-way movement distance X2 of the brush roller 34 and the one-way movement distance X1 of the photosensitive drum 10 The height of the cam surface and the cam follower is set so that the distance to which is added is 0.5 mm or more. Further, the cam surface 63a and the cam follower 61b are formed so that the number of reciprocating movements during one rotation is a predetermined number (for example, one reciprocation during one rotation).

  Simultaneously with the rotation of the photosensitive drum 10 and the brush roller 34, the photosensitive drum 10 reciprocates in the axial direction, and the brush roller 34 also reciprocates in the axial direction. At this time, since the number of teeth of the gear portions 51a and 61a of the gear members 51 and 61 of the photosensitive drum 10 and the brush roller 34 are different, the time for one rotation of the photosensitive drum 10 and the brush roller 34 is different. As a result, the cycle of the reciprocating movement of the photosensitive drum 10 and the cycle of the reciprocating movement of the brush roller 34 are different. In this example, the brush roller 34 makes one or more revolutions while the photosensitive drum 10 makes one revolution. Therefore, the brush roller 34 makes one or more reciprocations while the photosensitive drum 10 makes one reciprocation.

  The reciprocating movement of the photosensitive drum 10 and the brush roller 34 may be performed every time the photosensitive drum 10 rotates by a predetermined number of rotations (for example, 15 rotations). In this case, the cam members 53 and 63 of the photosensitive drum 10 and the brush roller 34 and the support shafts 10a and 34a can be rotated at the same position as the state where each cam member is fixed to a predetermined position of each support shaft. It is configured to be able to switch to a different state.

  In a state where the cam members 53 and 63 are rotatable, the gear members 51 and 61 are urged in the direction of the cam members 53 and 63 by the urging members 57 and 67, so that the gear members 51 and 61 and the cam member 53, 63 will rotate together. Therefore, the cam mechanism does not move in the axial direction, and the photosensitive drum 10 and the brush roller 34 do not move in the axial direction.

  In this case, for example, during normal times, the cam members 53 and 63 are made rotatable so that the photosensitive drum 10 and the brush roller 34 do not move in the axial direction. Since both the gear members 51 and 61 are engaged with each other and the brush roller 34 is rotated with the rotation of the photosensitive drum 10, the cleaning operation by the normal brush roller 34 is performed.

  Then, after the photosensitive drum 10 is rotated a predetermined number of times (for example, 15 times), the cam members 53 and 63 are switched to a state where they are fixed to the support shafts 10a and 34a. As a result, the photosensitive drum 10 and the brush roller 34 can reciprocate in the axial direction, and a cleaning operation for reciprocally moving both in the axial direction at different periods is performed.

  Thus, the following effects can be obtained by reciprocally moving the photosensitive drum 10 and the brush roller 34 in the axial direction at different periods. When the photosensitive drum 10 is moved in the axial direction, it is possible to reduce the time that foreign matter such as paper dust stays at one place of the contact portion between the cleaning blade 33 and the photosensitive drum 10, and the probability of occurrence of pinching decreases. To do. On the other hand, by moving the brush roller 34 in the axial direction, even when the rigidity of the brush 34c of the brush roller 34 is low and the contact is soft, it is possible to disperse the portion where the tip of the brush 34c abuts and uniformly apply it to the contact portion. it can. However, if the reciprocating motions of the two are synchronized, the position where the brush 34c of the brush roller 34 contacts the photosensitive drum 10 does not change, so that it is difficult to obtain the effect of the brush. In the present invention, since the foreign matter is less likely to stay due to the reciprocating movement of the photosensitive drum 10 and the period of the reciprocating motion is shifted so that the brush uniformly contacts the contact portion, Can be scraped off. In this method, since a soft brush can be used, even if an organic photoconductor that is easy to scrape is used, the life of the photoconductor is hardly affected.

  The one-way moving distance X1 of the photosensitive drum 10 is in the range of 0.1 mm to 0.3 mm as described above. The longer this distance is, the higher the effect of preventing the foreign matter from being caught, but if it exceeds 0.3 mm, the possibility of image distortion or the like increases. Further, if the thickness is 0.1 mm or less, a sufficient effect cannot be expected.

  On the other hand, since the brush roller 34 is less likely to cause defects such as image defects even when the moving distance is long, the moving distance X2 is preferably larger than the moving distance X1 of the photosensitive drum 10. However, the apparatus does not increase in size as the moving distance becomes longer, and the distance obtained by adding the one-way moving distance X1 of the photosensitive drum 10 and the one-way moving distance X2 of the brush roller 34 is 0.5 mm or more. As a result, a sufficient effect can be obtained.

  Further, even if the photosensitive drum 10 and the brush roller 34 have the same reciprocating cycle, it is sufficient that the moving direction is opposite. In this case, the relative position between the photosensitive drum 10 and the brush roller 34 is shifted during movement, and the portion where the tip of the brush hits the photosensitive drum 10 moves. Therefore, the same foreign matter removing effect as that when the period is shifted is obtained. Can be obtained.

  In the above-described embodiment of the present invention, the method of reciprocating the photosensitive drum 10 and the brush roller 34 every time the photosensitive drum 10 rotates a predetermined number of times has been described. However, the photosensitive drum 10 is rotated by a predetermined number of rotations. While rotating (while rotating), the two may be reciprocated at different periods.

  The present invention is limited to the above-described embodiment as long as the photosensitive drum 10 and the brush roller 34 can be reciprocated so as not to have the same period by setting the gear ratio and forming the cam. Is not to be done.

  In the present embodiment, the case where the configuration of the present invention is applied to the color printer 1 has been described. However, in another different embodiment, the configuration of the present invention is applied to an image forming apparatus other than the printer 1 such as a copying machine, a facsimile machine, or a multifunction peripheral. May be applied.

DESCRIPTION OF SYMBOLS 1 Color printer 10 Photosensitive drum 10a Support shaft 14 Cleaning apparatus 33 Cleaning blade 34 Brush roller 34a Support shaft

Claims (4)

A photosensitive drum that rotates around a support shaft to form a toner image, a cleaning blade that cleans the photosensitive drum after transferring the toner image, a cleaning blade that rotates around a support shaft and the photosensitive drum An image forming apparatus comprising: a brush roller that rotates and contacts a contact portion with a body drum;
The photosensitive drum reciprocates in the axial direction of the support shaft, and the brush roller reciprocates in the axial direction of the support shaft.
2. An image forming apparatus according to claim 1, wherein a cycle or direction of the reciprocating movement of the photosensitive drum is different from that of the brush roller.   The image forming apparatus according to claim 1, wherein a one-way moving distance when the photosensitive drum makes one reciprocation is in a range of 0.1 mm to 0.3 mm.   3. The image forming apparatus according to claim 1, wherein a one-way movement distance when the brush roller makes one reciprocation is longer than a one-way movement distance when the photosensitive drum makes one reciprocation.   2. The distance obtained by adding one-way movement distance when the brush roller makes one reciprocation and one-way movement distance when the photosensitive drum makes one reciprocation is 0.5 mm or more. The image forming apparatus according to 2 or 3.

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