JP5736342B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an image forming apparatus including a developing device and an image carrier unit that are detachably attached to the image forming device.

  In the conventional image forming apparatus, the drum unit (image carrier unit) including the photosensitive drum is replaced when the number of printed sheets reaches a predetermined number (for example, tens of thousands) due to the life of the photosensitive drum (image carrier). There is a need to do. In some cases, maintenance or replacement of the developing device disposed adjacent to the drum unit may be required.

  Here, the developing roller of the developing device is disposed in contact with or close to the photosensitive drum. Therefore, when the drum unit or the developing device is replaced, the photosensitive drum and the developing roller come into contact with each other, and there is a possibility that the surface of the photosensitive drum or the developing roller is damaged.

  Accordingly, various mechanisms have been devised for retracting the developing roller disposed in contact with or close to the photosensitive drum from the photosensitive drum. For example, Patent Document 1 discloses that after the developing device is mounted on the image forming apparatus main body. The developing roller is brought into contact with the photosensitive drum in accordance with the closing operation of the holder member (drum positioning unit) on which the positioning plate for positioning the drum shaft of the photosensitive drum is mounted, and the developing roller in accordance with the opening operation of the holder member. An image forming apparatus having a roller contact / separation mechanism for retracting the toner from the photosensitive drum is disclosed.

  The roller contact / separation mechanism of Patent Document 1 is arranged so as to be able to rotate integrally with the developing roller and to be movable along the axial direction of the developing roller, and develops the arm member when moving in the axial direction. The shaft member is configured to rotate integrally with the roller. The shaft member moves in the axial direction by pressing the tip of the shaft member protruding to the front side of the developing device with the holder member to bring the developing roller into contact with the photosensitive drum, and the shaft member is released by opening the holder member. The developing roller is moved away from the photosensitive drum by moving in the opposite direction by the biasing force of the spring.

JP 2011-191603 A

  However, in the configuration of Patent Document 1, the tip of the shaft member that appears and disappears on the front side of the four developing devices corresponding to each color is pressed by the holder member at a time, so the pressing load on the holder member increases. For example, when the pressing load on the shaft member of one developing device is 15N, the pressing load is four times 60N in four developing devices. Therefore, the operation of the holder member becomes heavy and the operability is lowered, and the strength of the holder member is also required.

  Here, if the tip of the shaft member protrudes and retracts to the rear side of the developing device, the shaft member is pushed in as the developing device is inserted into the image forming apparatus main body, and the developing device is pulled out from the image forming apparatus main body. Accordingly, since the shaft member protrudes, the shaft members of the four developing devices can be individually operated, and the operation load on the holder member can be reduced.

  However, in this configuration, since the developing roller is in contact with or close to the photosensitive drum when the developing device is mounted on the image forming apparatus main body, the photosensitive drum and the developing roller are removed when the drum unit is attached or detached while the developing device is mounted. Will come into contact. For this reason, the order of attaching and detaching the developing device and the drum unit is limited, and there is a problem that the replacement workability is deteriorated.

  In view of the above problems, an object of the present invention is to provide an image forming apparatus excellent in workability in which an image carrier unit and a developing device can be attached and detached in any order.

  To achieve the above object, the present invention provides an image carrier having an image carrier on which an electrostatic latent image is formed, and is detachably disposed on the image forming apparatus main body, and the image carrier. A developing device that is disposed so as to approach or retract and has a developing roller that supplies toner onto the image carrier, and is detachably disposed adjacent to the image carrier unit, and the developing device and the image carrier A positioning member disposed on the downstream side in the mounting direction of the body unit and formed with a bearing hole into which the rotation shaft of the image carrier is fitted, and provided so as to be able to protrude from the downstream side in the mounting direction of the developing device facing the positioning member. And an urging member that urges the shaft member in a direction protruding from the developing device, and the image bearing member is supported by pushing the shaft member into the developing device. A roller contacting / separating mechanism for retracting the developing roller from the image carrier by causing the shaft member to protrude from the developing device, and a mounting state of the image carrier unit and the developing device are individually maintained. And a locking mechanism capable of releasing the holding, wherein the positioning member has a first abutting portion against which an end portion of the shaft member protruding from the developing device abuts, and the image carrier. A rocking member having a second abutting portion with which a part of the unit abuts, and a rocking fulcrum provided between the first abutting portion and the second abutting portion are the image carrier unit and It is disposed at a position corresponding to the developing device, and in a state where a part of the image carrier unit and the second contact portion are in contact with each other, the swing of the swing member is restricted, and the shaft member is The first The shaft member is pushed into the developing device by contact with a portion, and the swing member is allowed to swing when a part of the image carrier unit and the second contact portion are separated from each other, and the shaft member Is protruded from the developing device by the first urging member.

  According to the present invention, in the image forming apparatus having the above-described configuration, the swinging member is an annular frame body in a plan view, and the first contact portion and the second contact portion are disposed at two opposing positions on the frame body. And the rocking fulcrum is provided at two locations that are substantially equidistant from the first contact portion and the second contact portion.

  According to the present invention, in the image forming apparatus having the above-described configuration, when the holding state of the image carrier unit or the developing device is released by the lock mechanism, the image carrier is applied by the urging force of the first urging member. The body unit or the developing device protrudes upstream in the mounting direction.

  According to the present invention, in the image forming apparatus having the above-described configuration, a plurality of the image carrier units and the developing devices are provided corresponding to different colors, and the swing member is the image of the positioning member. A plurality of the units are arranged at positions corresponding to the carrier unit and the developing device.

  According to the present invention, the image forming apparatus having the above-described configuration includes an image carrier positioning unit disposed so as to be openable and closable adjacent to the upstream side in the mounting direction of the image carrier unit and the developing device.

  According to the first configuration of the present invention, when the image carrier unit is not inserted into the image forming apparatus main body, the swinging member is allowed to swing, and the shaft member protrudes from the developing device. When the image carrier unit is inserted into the image forming apparatus main body and abuts against the second abutting portion of the oscillating member, the oscillation of the oscillating member is restricted and the shaft member is in contact with the first abutting portion. The toner is pushed into the developing device by the contact, and the developing roller approaches the image carrier. Accordingly, the contact between the developing roller and the image carrier can be avoided regardless of the order in which the developing device and the image carrier unit are attached and detached, so that the surface of the image carrier and the developing roller is damaged. No fear.

  According to the second configuration of the present invention, in the image forming apparatus having the first configuration, the swinging member is an annular frame in plan view, and the first abutting portion is provided at two opposing positions on the frame. And the second abutting portion, and by providing swinging fulcrums at two locations that are substantially equidistant from the first abutting portion and the second abutting portion, the image carrier can be inserted when the image carrier unit is inserted. In addition, since the rotation shaft of the developing roller passes through the inside of the frame, it is possible to avoid interference between the swinging member and the image carrier unit or the developing device.

  According to the third configuration of the present invention, in the image forming apparatus having the first or second configuration, when the holding state of the image carrier unit or the developing device is released by the lock mechanism, As the image carrier unit or the developing device protrudes upstream in the mounting direction by the urging force of the urging member, the operator can grasp and pull out the end of the developing device or image carrier unit that has popped out, The take-out property of the developing device and the image carrier unit is improved.

  According to the fourth configuration of the present invention, in the image forming apparatus having any one of the first to third configurations, a plurality of image carrier units and developing devices are provided corresponding to different colors. By arranging a plurality of swing members at positions corresponding to the image carrier unit and the developing device of the positioning member, the developing device or the adjacent image carrier unit is inserted into the shaft member protruding from each developing device. Since the image carrier unit and the developing device are replaced, the operation load can be reduced.

  According to the fifth configuration of the invention, in the image forming apparatus having the fourth configuration, the image carrier is disposed so as to be openable and closable adjacent to the upstream side in the mounting direction of each image carrier unit and each developing device. By providing the body positioning unit, each image carrier has a positioning member disposed on the downstream side in the mounting direction of each image carrier unit and an image carrier positioning unit disposed on the upstream side in the mounting direction. Positioned reliably. Further, when the image carrier positioning unit is closed, the pressing load of the shaft member of each developing device is not applied at once, so that the operability of the image carrier positioning unit is improved and the positioning accuracy of each image carrier is also improved. Since it is not necessary to increase the rigidity of the carrier positioning unit, the configuration can be simplified.

1 is a schematic cross-sectional view showing an internal configuration of an image forming apparatus 200 according to an embodiment of the present invention. 1 is an enlarged cross-sectional view near the image forming portion Pa in FIG. External perspective view of developing device 3a detachably mounted on image forming apparatus 200 as viewed from the upstream side in the direction of insertion into image forming apparatus 200 Schematic side view schematically showing the roller contact / separation mechanism 51 of the developing device 3a FIG. 4 is a schematic view of the relationship between the roller contact / separation mechanism 51, the developing roller 29, and the photosensitive drum 1a as viewed from the right in FIG. External perspective view of shaft member 53 constituting roller contact / separation mechanism 51 FIG. 4 is a partial perspective view of the developing device 3a as viewed from the downstream side in the insertion direction (the back side in FIG. 3), and shows a state where the developing roller 29 is brought close to the photosensitive drum 1a. FIG. 4 is a partial perspective view of the developing device 3a as viewed from the downstream side in the insertion direction (the back side in FIG. 3), and shows a state where the developing roller 29 is retracted from the photosensitive drum 1a. External perspective view of drum unit 40a detachably mounted on image forming apparatus 200 as viewed from the upstream side in the direction of insertion into image forming apparatus 200 The perspective view which looked at the retainer 90 from the front side of the image forming apparatus 200 Front view of the image forming apparatus 200 showing a state in which the waste toner conveying unit 100 and the retainer 90 are opened. FIG. 11 is an enlarged view of the vicinity of the drum units 40c and 40d and the developing devices 3c and 3d. The partial perspective view which looked at the drum unit 40a from the insertion direction downstream side (back side of FIG. 9). The perspective view which looked at the positioning member 70 arrange | positioned in the insertion direction downstream of developing device 3a-3d and drum unit 40a-40d from the back side of the image forming apparatus 200. The perspective view which looked at the state which mounted developing devices 3a-3d and drum units 40a-40d to positioning member 70 from the back side of image forming device 200. The perspective view which shows the positional relationship of the developing device 3a inserted in the image forming apparatus 200, the drum unit 40a, and the rocking | swiveling member 73a. The top view which shows the positional relationship of the developing device 3a inserted in the image forming apparatus 200, the drum unit 40a, and the rocking | swiveling member 73a. FIG. 17 is a plan view showing the positional relationship between the developing device 3a, the drum unit 40a, and the swinging member 73a when the developing device 3a is pulled out from the state of FIG. FIG. 17 is a plan view showing the positional relationship between the developing device 3a and the drum unit 40a and the swinging member 73a when the drum unit 40a is pulled out from the state of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience of explanation below, directions are defined as follows. First, in the image forming apparatus 200 shown in FIG. 1, the direction in which the drum axes of the photosensitive drums 1a to 1d are arranged is the X direction, the direction perpendicular to the plane including each drum axis is the Y direction, and the X direction and the Y direction are the same. The vertical direction (drum axis direction) is taken as the Z direction. That is, in FIG. 1, the X direction corresponds to the left-right direction, the Y direction corresponds to the up-down direction, and the Z direction corresponds to the front-rear direction. In addition, the positive / negative direction of each direction of X, Y, and Z is not ask | required here.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. In this embodiment, the image forming apparatus 200 performs image formation by arranging four photosensitive drums 1a, 1b, 1c, and 1d corresponding to four different colors (magenta, cyan, yellow, and black) in parallel. Consists of a tandem color printer.

  In the apparatus main body of the image forming apparatus 200, four image forming sections Pa, Pb, Pc, and Pd are sequentially arranged from the left side in FIG. These image forming portions Pa to Pd are provided corresponding to images of four different colors (magenta, cyan, yellow, and black), and magenta, cyan, and yellow are respectively subjected to charging, exposure, development, and transfer processes. And a black image are sequentially formed.

  Each of the image forming portions Pa to Pd is provided with the above-described photosensitive drums 1a to 1d that carry visible images (toner images) of the respective colors, and further rotate counterclockwise in FIG. An intermediate transfer belt 8 is provided adjacent to each of the image forming portions Pa to Pd. The toner images formed on the photosensitive drums 1 a to 1 d are sequentially transferred onto the intermediate transfer belt 8 that moves while contacting the photosensitive drums 1 a to 1 d, and then the paper P is transferred by the secondary transfer roller 9. Then, the toner image is transferred onto the sheet P in the fixing device 13 and then discharged from the image forming apparatus 200. While the photosensitive drums 1a to 1d are rotated in the clockwise direction in FIG. 1, an image forming process for the photosensitive drums 1a to 1d is executed.

  The paper P on which the toner image is transferred is accommodated in a paper cassette 16 disposed in the lower part of the image forming apparatus 200, and is transferred to the secondary transfer roller 9 via the paper feed roller 12a and the registration roller pair 12b. Be transported. A sheet made of dielectric resin is used for the intermediate transfer belt 8, and a (seamless) belt mainly having no seam is used. The intermediate transfer belt 8 and the secondary transfer roller 9 are rotationally driven at the same linear speed as the photosensitive drums 1a to 1d by a belt drive motor (not shown). Further, a blade-like belt cleaner 19 for removing toner remaining on the surface of the intermediate transfer belt 8 is disposed on the downstream side of the secondary transfer roller 9.

  Next, the image forming units Pa to Pd will be described. Around the photosensitive drums 1a to 1d arranged rotatably, there are charging devices 2a, 2b, 2c and 2d for charging the photosensitive drums 1a to 1d, and the photosensitive drums 1a to 1d. An exposure unit 5 that performs exposure based on image data, developing devices 3a, 3b, 3c, and 3d that develop the electrostatic latent images formed on the photosensitive drums 1a to 1d with toner, and the photosensitive drums 1a to 1d Are provided with cleaning devices 7a, 7b, 7c and 7d for collecting and removing the developer (toner) remaining after the transfer of the toner image.

  When image data is inputted from a host device such as a personal computer, first, the surfaces of the photosensitive drums 1a to 1d are uniformly charged by the charging devices 2a to 2d, and then light is irradiated by the exposure unit 5 based on the image data. The electrostatic latent images corresponding to the image data are formed on the respective photosensitive drums 1a to 1d. Each of the developing devices 3a to 3d includes a developing roller (developer carrying member) disposed so as to face the photosensitive drums 1a to 1d, and a predetermined amount of two-component developer containing toners of each color of magenta, cyan, yellow, and black, respectively. Filled.

  In addition, when the ratio of the toner in the two-component developer filled in each developing device 3a to 3d falls below a specified value due to the formation of a toner image described later, each developing device 3a to 3d is transferred from the toner container 4a to 4d. Toner is replenished. The toner is supplied onto the photosensitive drums 1a to 1d by the developing devices 3a to 3d and electrostatically attached to form a toner image corresponding to the electrostatic latent image formed by exposure of the exposure unit 5. Is done.

  Then, by applying a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d by the primary transfer rollers 6a to 6d, magenta, cyan, yellow on the photosensitive drums 1a to 1d and A black toner image is primarily transferred onto the intermediate transfer belt 8. These four color images are formed with a predetermined positional relationship predetermined for forming a predetermined full-color image. The primary transfer rollers 6a to 6d are rotationally driven at the same linear speed as the photosensitive drums 1a to 1d and the intermediate transfer belt 8 by a primary transfer drive motor (not shown). Thereafter, the toner remaining on the surfaces of the photosensitive drums 1a to 1d is removed by the cleaning devices 7a to 7d in preparation for the subsequent formation of a new electrostatic latent image.

  The intermediate transfer belt 8 is stretched between a driven roller 10 and a drive roller 11, and when the intermediate transfer belt 8 starts to rotate counterclockwise as the drive roller 11 is rotated by the belt drive motor, the sheet P is loaded. The sheet is conveyed from the registration roller pair 12b to the nip portion (secondary transfer nip portion) between the secondary transfer roller 9 and the intermediate transfer belt 8 provided adjacent to the intermediate transfer belt 8 at a predetermined timing. A full-color image is secondarily transferred to the image. The sheet P on which the toner image is transferred is conveyed to the fixing device 13.

  The sheet P conveyed to the fixing device 13 is heated and pressurized when passing through the nip portion (fixing nip portion) of the pair of fixing rollers 13a to fix the toner image on the surface of the sheet P, and a predetermined full color image is formed. It is formed. The paper P on which the full-color image is formed is distributed in the transport direction by the branching section 14 that branches in a plurality of directions. When an image is formed on only one side of the paper P, it is discharged to the discharge tray 17 by the discharge roller pair 15 as it is.

  On the other hand, when forming images on both sides of the paper P, a part of the paper P that has passed through the fixing device 13 is once projected from the discharge roller pair 15 to the outside of the device. Thereafter, the paper P is distributed to the reverse conveyance path 18 by the branching section 14 by rotating the discharge roller pair 15 in the reverse direction, and is conveyed again to the secondary transfer roller 9 with the image surface reversed. Then, after the next image formed on the intermediate transfer belt 8 is transferred to the surface of the paper P where the image is not formed by the secondary transfer roller 9 and conveyed to the fixing device 13 to fix the toner image, The paper is discharged to the discharge tray 17 by the discharge roller pair 15.

  Next, details of the above-described image forming unit Pa will be described. Since the image forming units Pb to Pd have basically the same configuration as the image forming unit Pa, detailed description thereof is omitted. FIG. 2 is an enlarged sectional view showing the vicinity of the image forming portion Pa in FIG. Around the photosensitive drum 1a, the above-described charging device 2a, developing device 3a, primary transfer roller 6a, and cleaning device 7a are arranged along the drum rotation direction (clockwise direction in FIG. 2). Among these, the primary transfer roller 6a is disposed at a position facing the photosensitive drum 1a with the intermediate transfer belt 8 interposed therebetween.

  The photosensitive drum 1a, the charging device 2a, and the cleaning device 7a are unitized. In each of the image forming units Pa to Pd, units including the photosensitive drums 1a to 1d, the charging devices 2a to 2d, and the cleaning devices 7a to 7d are hereinafter referred to as drum units 40a to 40d.

  The charging device 2 a includes a charging roller 21 that contacts the photosensitive drum 1 a and applies a charging bias to the drum surface, and a charging cleaning roller 23 for cleaning the charging roller 21. The developing device 3a includes two agitating and conveying screws 25, a magnetic roller 27, and a developing roller 29, and a developing bias having the same polarity (positive) as the charging polarity of the toner is applied to the developing roller 29 to form a drum surface. Let the toner fly.

  The cleaning device 7 a includes a rubbing roller (abrasive member) 30, a cleaning blade 31, and a collection spiral 33. The rubbing roller 30 is pressed against the photosensitive drum 1a with a predetermined pressure, and is driven to rotate in the same direction on the contact surface with the photosensitive drum 1a by a drum cleaning motor (not shown). The speed is controlled to be faster (1.2 times here) than the linear speed of the photosensitive drum 1a. Examples of the rubbing roller 30 include a structure in which a foam layer made of EPDM rubber and having an Asker C hardness of 55 ° is formed as a roller body around a metal shaft. The material of the roller body is not limited to EPDM rubber, but may be a rubber or foamed rubber body of another material, and those having an Asker C hardness of 10 to 90 ° are preferably used.

  In addition, Asker C is one of durometers (spring type hardness testers) defined in the Japan Rubber Association standard, and is a measuring instrument for measuring hardness. Asker C hardness refers to the hardness measured with the above measuring instrument, and the larger the value, the harder the material.

  A cleaning blade 31 is fixed in contact with the photosensitive drum 1a on the surface of the photosensitive drum 1a downstream of the contact surface with the rubbing roller 30 in the rotation direction. As the cleaning blade 31, for example, a polyurethane rubber blade having a JIS hardness of 78 ° is used, and is attached at a predetermined angle with respect to the tangential direction of the photosensitive member at the contact point. The material, hardness, dimensions, the amount of biting into the photosensitive drum 1a, the pressure contact force, and the like of the cleaning blade 31 are appropriately set according to the specifications of the photosensitive drum 1a. The JIS hardness refers to the hardness specified by Japanese Industrial Standards (JIS).

  The residual toner removed from the surface of the photosensitive drum 1a by the rubbing roller 30 and the cleaning blade 31 is discharged to the outside of the cleaning device 7a (see FIG. 2) as the collection spiral 33 rotates. Examples of the toner used in the present invention include those in which an abrasive selected from silica, titanium oxide, strontium titanate, alumina and the like is embedded in the toner particle surface and held so as to partially protrude on the surface. In which the toner is electrostatically attached to the toner surface.

  In this way, the surface of the photosensitive drum 1 a is polished by the residual toner containing the abrasive by rotating the rubbing roller 30 with a speed difference with respect to the photosensitive drum 1 a, and the drum is formed by the rubbing roller 30 and the cleaning blade 31. Surface moisture and discharge products are removed together with residual toner.

  The layout inside the main body of the image forming apparatus 200 can be changed as appropriate as long as the rotation directions of the photosensitive drums 1a to 1d and the intermediate transfer belt 8 and the conveyance path of the paper P can be appropriately set. For example, the rotational directions of the photosensitive drums 1a to 1d and the intermediate transfer belt 8 are reversed from the present embodiment, and the positional relationship between the drum units 40a to 40d and the developing devices 3a to 3d is reversed from the present embodiment. Of course, it is possible to set the transport path of the paper P in accordance with this.

  FIG. 3 is an external perspective view of the developing device 3a as viewed from the upstream side in the insertion direction of the image forming apparatus 200. Since the developing devices 3b to 3d have basically the same configuration as the developing device 3a, description thereof is omitted. The developing device 3a includes the above-described two agitating and conveying screws 25, a magnetic roller 27, and a developing roller 29 (see FIG. 2) inside a housing 50. The housing 50 includes a toner container 4a (see FIG. 1). A toner supply port 50a connected to a toner supply unit (not shown) for supplying the toner from is formed. Corresponding color (magenta in this case) toner is supplied into the developing device 3a through the toner supply port 50a, and is used for developing the electrostatic latent image.

  Further, the developing device 3a includes a roller contact / separation mechanism 51 (see FIG. 5) that causes the developing roller 29 to approach or retract from the photosensitive drum 1a, and a roller contact / separation mechanism is provided on a side surface of the developing device 3a. A shaft member 53 constituting 51 is disposed. The shaft member 53 is slidably disposed along a groove-shaped guide portion 50d formed on the outer surface of the housing 50 of the developing device 3a. Then, from the rear surface of the developing device 3 a facing the positioning device 70 (see FIG. 14) of the image forming apparatus 200, driving for inputting a driving force to the tip 53 a (see FIG. 6) of the shaft member 53 and the developing roller 29. A coupling 59 protrudes. FIG. 3 shows a state in which the shaft member 53 is exposed by removing a side cover (not shown) that seals the guide portion 50d.

  A duct connecting portion 50b connected to a suction duct for sucking the floating toner in the developing device 3a is formed on the front surface of the developing device 3a. Further, a fitting hole 50c into which a positioning boss of a retainer 90 (see FIG. 10) disposed inside the opening / closing cover is fitted is formed below the duct connecting portion 50b. Further, on the front surface of the developing device 3a, an engaging claw 35 that engages with the front plate 101 (see FIG. 11) when the developing device 3a is inserted into the image forming apparatus 200, and the engagement of the engaging claw 35 are released. An unlock lever 37 is provided. The engaging claw 35 and the lock release lever 37 constitute a lock mechanism that holds the developing device 3a in a mounted state and can release the hold.

  FIG. 4 is a schematic side view of the roller contact / separation mechanism 51, and FIG. 5 is a schematic view of the relationship between the roller contact / separation mechanism 51, the developing roller 29, and the photosensitive drum 1a viewed from the axial direction (left direction in FIG. 4). FIG. 6 and FIG. 6 are external perspective views of the shaft member 53 constituting the roller contact / separation mechanism 51. A mechanism for approaching and retracting the developing roller 29 from the photosensitive drums 1a to 1d by the roller contact / separation mechanism 51 will be described with reference to FIGS. Here, the roller contact / separation mechanism 51 of the developing device 3a will be described, but the description is omitted because the same applies to the developing devices 3b to 3d. The roller contact / separation mechanism 51 includes arm members 52 a and 52 b, a shaft member 53, a first coil spring 54, a bearing member 55, and a second coil spring 56.

  The shaft member 53 is made of a material having a predetermined rigidity and is a rod-like member disposed along the longitudinal direction of the developing device 3a. The shaft member 53 is disposed so as to be movable in the axial direction (arrow AA ′ direction). Yes. As shown in FIG. 6, on the rear side in the axial direction of the shaft member 53, a tip end portion 53a capable of coming into contact with a swinging member 73a (see FIG. 11) provided in the positioning device 70 is formed. In the vicinity of both end portions of 53, two ribs 53b projecting downward from the outer peripheral surface of the shaft member 53 are formed at positions corresponding to the arm members 52a and 52b. The rib 53b has a fin shape in a side view in which the amount of protrusion from the outer peripheral surface gradually changes along the axial direction of the shaft member 53. In addition, a hook-shaped engaging portion 53 c that engages with one end of the first coil spring 54 is formed at a substantially central portion in the longitudinal direction of the shaft member 53.

  The first coil spring 54 is a tension spring. One end of the first coil spring 54 engages with the engaging portion 53c and the other end is fixed to the housing 50. The distal end portion 53a of the shaft member 53 protrudes from the rear surface of the developing device 3a in a free state. Thus, the shaft member 53 is urged toward the rear side in the axial direction (arrow A ′ direction). The bearing member 55 is formed integrally with the arm members 52a and 52b, functions as a link member that receives both ends of the rotating shafts 27a and 29a of the magnetic roller 27 and the developing roller 29, and connects the rollers 27 and 29. The magnetic roller 27 swings integrally in the direction of the arrow BB ′ around the rotation shaft 27a.

  Accordingly, when the bearing member 55 swings around the rotation shaft 27a, the developing roller 29 swings around the magnetic roller 27 together with the bearing member 55 to approach or retract from the photosensitive drum 1a. A second coil spring 56 is fixed to the bearing member 55, and the bearing member 55 is urged by the second coil spring 56 in a direction that swings in the direction of arrow B. The bearing member 55 may be a separate member from the arm members 52a and 52b.

  As shown in FIGS. 4 and 5, when the tip 53a of the shaft member 53 protrudes from the developing device 3a, the arm members 52a and 52b ride on the ribs 53b and are pushed down, and the developing roller 29 is exposed to light. It is in a position retracted from the body drum 1a. When the tip 53a is pushed into the developing device 3a from this state, the shaft member 53 moves forward in the axial direction (in the direction of arrow A), so that the arm members 52a and 52b drop off from the rib 53b. The bearing members 55 connected to the arm members 52 a and 52 b swing in the direction of arrow B about the rotation shaft 27 a by the urging force of the second coil spring 56. As a result, the developing roller 29 approaches the photosensitive drum 1a.

  On the other hand, when the pressing of the distal end portion 53a is released, the shaft member 53 moves rearward in the axial direction (in the direction of the arrow A ′) by the biasing force of the first coil spring 54, whereby each arm member 52a, 52b rides on the rib 53b, Each arm member 52a, 52b swings in the direction of arrow B ′ about the rotation shaft 27a. Since the bearing member 55 as well as the arm members 52a and 52b swings in the direction of the arrow B ′ against the biasing force of the second coil spring 56, the developing roller 29 is retracted from the photosensitive drum 1a.

  A bearing 57 is attached at a position where the shaft member 53 of the arm members 52a and 52b contacts. As a result, when the shaft member 53 is reciprocated to move the developing roller 29 toward or away from the photosensitive drum 1a, the bearing 57 is rotated so that a load due to friction between the arm members 52a and 52b and the shaft member 53 is applied. Reduced.

  7 and 8 are partial perspective views of the vicinity of the downstream end (back side in FIG. 3) of the developing device 3a in the insertion direction. FIG. 7 shows a state in which the developing device 3a is inserted into the image forming apparatus 200. When the developing device 3a is inserted, the tip end portion 53a is brought into pressure contact with the swing member 73a (see FIG. 14). The shaft member 53 moves in a direction to be pushed into the housing 50. As a result, the bearing 57 attached to the arm members 52a and 52b (see FIG. 5) falls off from the rib 53b. In this state, the bearing member 55 swings around the rotation shaft 27a in the direction of arrow B in FIG. 5 by the urging force of the second coil spring 56 (both see FIG. 5), and the developing roller 29 approaches the photosensitive drum 1a. doing.

  FIG. 8 shows a state in which the developing device 3a is pulled out from the image forming apparatus 200. As the developing device 3a is pulled out, the developing device 3a moves away from the swinging member 73a (see FIG. 14). The shaft member 53 moves in a direction protruding from the housing 50 by the biasing force of the first coil spring 54. As a result, the bearing 57 attached to the arm members 52a and 52b (see FIG. 5) rides on the rib 53b. In this state, the bearing member 55 swings around the rotation shaft 27a in the direction of arrow B 'in FIG. 5 against the urging force of the second coil spring 56 (see FIG. 5), and the developing roller 29 is moved to the photosensitive member. It is separated from the drum 1a.

  FIG. 9 is an external perspective view of the drum unit 40a used in combination with the developing device 3a as viewed from the upstream side in the insertion direction into the image forming apparatus 200. FIG. Note that the drum units 40b to 40d have basically the same configuration as the drum unit 40a, and a description thereof will be omitted. The drum unit 40a has a toner disposal port 41a in addition to the photosensitive drum 1a, the charging device 2a, and the cleaning device 7a. The waste toner collected by the cleaning device 7a is discharged from the toner waste port 41a and is transported to a recovery container (not shown) via the waste toner transport unit 100 (see FIG. 11).

A drum shaft 1a ₁ that is a rotation shaft of the photosensitive drum 1a protrudes from the front surface and the rear surface of the drum unit 40a. The drum shaft 1a ₁ protruding from the front surface of the drum unit 40a is fitted into a bearing hole of a retainer 90 (see FIG. 10) disposed inside an opening / closing cover (not shown) on the front surface side of the image forming apparatus 200. On the other hand, the drum shaft 1a ₁ protruding from the rear surface of the drum unit 40a is fitted into a bearing hole of a positioning member 70 (see FIG. 11) disposed on the back side of the image forming apparatus 200. In addition, a protrusion 60 that projects in the same direction as the drum shaft 1a ₁ is provided on the rear surface of the drum unit 40a.

  Further, on the front surface of the drum unit 40a, there are an engagement claw 45 that engages with the front side plate 101 (see FIG. 11) when the drum unit 40a is inserted into the image forming apparatus 200, and a lock that releases the engagement of the engagement claw 45. A release lever 47 is provided. The engagement claw 45 and the lock release lever 47 constitute a lock mechanism that holds the drum unit 40a in a mounted state.

  FIG. 10 is a perspective view of the retainer 90 as viewed from the front side (outside) of the image forming apparatus 200. FIG. 11 is a front view showing a state in which the waste toner transport unit 100 and the retainer 90 are opened. FIG. 12 is an enlarged view in the vicinity of the developing devices 3c and 3d and the drum units 40c and 40d in FIG.

The retainer 90 rotates while holding a positioning plate (not shown) around the rotation shaft 90a, thereby allowing the drum shafts 1a ₁ , 1b ₁ , 1c ₁ , and 1d ₁ to move relative to the bearing holes of the positioning plate. This is a holding member that is relatively inserted and removed. The retainer 90 is configured by connecting both ends of the rotation shaft 90 a and the main body 91 with connecting portions 92 and 92, and has hooks 93 and 93 and a lever 94.

  The main body 91 is elongated in the X direction as a whole, and the shape in the cross section perpendicular to the rotation shaft 90a is a concave shape opened on the side facing the front plate 101 (see FIG. 11) in the positioning completed state. ing. The positioning plate described above is located in the opening of the main body 91.

  In the main body 91, concave portions 95a, 95b, 95c, and 95d are formed. As a result, when the retainer 90 rotates, the toner disposal ports 41a to 41d (see FIG. 9) of the drum units 40a to 40d pass inside the recesses 95a to 95d of the main body 91, and the toner disposal ports 41a to 41d Interference with the retainer 90 is avoided.

Rotation shaft 90a is positioned parallel to the X direction the drum shaft 1a ₁ through 1d ₁ of the drum unit 40a~40d lined, and the image forming apparatus 200 main body so as to be positioned above the drum shaft 1a ₁ through 1d ₁ Supported by Since the rotation shaft 90a is positioned above the drum shafts 1a _{1 to} 1d ₁ , the retainer 90 can rotate about the rotation shaft 90a as a fulcrum so as to be opened downward with respect to the front surface of the image forming apparatus 200 main body. Supported by

  The hook protection parts 99 and 99 are provided so as to slightly protrude in the X direction from the main body 91 so as to cover the hooks 93 and 93 in a plane perpendicular to the rotation shaft 90a. doing. The hook protection portions 99 and 99 are open on the side facing the front side plate 101 so that the hooks 93 and 93 can be engaged with the front side plate 101.

  The hooks 93 and 93 are engaging members that engage with the holes of the front side plate 101 in which the drum units 40a to 40d are loaded, and are provided at both ends of the support shaft 93a supported by the main body 91. The shaft 93a is rotated integrally with the fulcrum. The hooks 93 and 93 are biased by a spring (not shown) in a rotational direction that engages with the hole of the front side plate 101. The support shaft 93a of the hooks 93 and 93 is provided in parallel (X direction) with the rotation shaft 90a of the retainer 90.

  The lever 94 is fixed to the central portion in the X direction of the rotation shaft 93a of the hooks 93, 93, and the hooks 93, 93 are arranged in the direction opposite to the rotation direction engaged with the apparatus main body with the rotation shaft 93a as a fulcrum. By rotating, the engagement of the hooks 93 and 93 with the front plate 101 is released.

  One end of a tension spring 97 is connected to one of the support shafts 93a of the hooks 93 and 93, and the other end of the tension spring 97 is fixed to the main body side of the image forming apparatus 200. Then, the relationship between the fixed position of the tension spring 97 and the rotation fulcrum (rotation shaft 90a) of the retainer 90 is determined so that the urging force of the tension spring 97 acts in a direction that assists the rotation operation of the retainer 90. .

  By holding the lever 94 to release the engagement between the hooks 93 and 93 and the front side plate 101 and rotating the retainer 90 upward, as shown in FIGS. 11 and 12, the developing devices 3a to 3d and the drum unit Since the front of 40a to 40d is widely opened, the developing devices 3a to 3d and the drum units 40a to 40d can be taken out and replaced. After replacement of the developing devices 3a to 3d or the drum units 40a to 40d, when the retainer 90 is turned downward from the state shown in FIG. 11 and closed, the hooks 93 and 93 and the front plate 101 are engaged, and the retainer 90 is engaged. Is kept closed.

  The waste toner transport device 100 is attached to and detached from the toner waste ports 41a to 41d of the drum units 40a to 40d, and collects the toner collected by the cleaning devices 7a to 7d (see FIG. 1) and discharged from the toner waste ports 41a to 41d. It is an apparatus which conveys to a collection container (not shown). The waste toner conveying device 100 is rotated with respect to the retainer 90 so as to open upward with respect to the front surface of the main body of the image forming apparatus 200 on the side (outside) opposite to the developing devices 3a to 3d and the drum units 40a to 40d. It is supported movably.

FIG. 13 is a partial perspective view of the drum unit 40a as viewed from the downstream side in the insertion direction (the back side in FIG. 9). FIG. 14 is arranged downstream in the insertion direction of the developing devices 3a to 3d and the drum units 40a to 40d. 3 is a perspective view of the positioning member 70 as viewed from the back side of the image forming apparatus 200. FIG. The positioning member 70, and four bearing holes 71a~71d the drum shaft 1a ₁ through 1d ₁ of each of the photosensitive drums 1a~1d passes, the drive coupling 59 of the developing devices 3 a to 3 d (see FIG. 7) The positioning frame 71 has four positioning holes 72 a to 72 d for positioning, and four swinging members 73 a to 73 d attached to the positioning frame 71.

  The rocking members 73a to 73d are metal frames having a rectangular shape in plan view, and a rocking fulcrum 77 (see FIG. 16) provided at substantially the center of two sides in the vertical direction is the back side of the positioning frame 71 (see FIG. It is swingably supported by four pairs of support columns 75a to 75d fixed to the developing devices 3a to 3d and the opposite side of the drum units 40a to 40d. With this configuration, each of the swing members 73a to 73d can swing in the horizontal direction (left and right direction in FIG. 14).

  FIG. 15 is a perspective view of the developing device 3a to 3d and the drum units 40a to 40d attached to the positioning member 70 as viewed from the outside of the image forming apparatus 200. FIG. 16 illustrates the direction in which the developing device 3a and the drum unit 40a are inserted. FIG. 17 is a partial plan view of the periphery of the downstream end of the developing device 3a and the drum unit 40a as viewed from above. In order to clarify the relationship among the developing device 3a, the drum unit 40a, and the swing member 73a, the positioning frame 71 is not shown in FIGS. Further, the relationship between the developing devices 3b to 3d, the drum units 40b to 40d, and the swinging members 73b to 73d is the same as in FIGS.

  As shown in FIGS. 16 and 17, a first contact portion 79a with which the tip end portion 53a of the shaft member 53 is in contact with the side of the swinging member 73a that faces the developing device 3a (the left side in FIG. 16). A second abutting portion 79b with which the protruding portion 60 abuts is provided on the side facing the drum unit 40a (the right side in FIG. 16).

  Next, the operation of the swing member 73a when the developing device 3a and the drum unit 40a are attached to and detached from the image forming apparatus 200 will be described. In a state where both the developing device 3a and the drum unit 40a are mounted, as shown in FIG. 17, on the developing device 3a side, the tip end portion 53a of the shaft member 53 contacts the first contact portion 79a of the swinging member 73a. Yes. On the drum unit 40a side, the protrusion 60 is in contact with the second contact portion 79b of the swinging member 73a.

  In the state of FIG. 17, the swinging of the swinging member 73a in the clockwise direction is restricted by the contact between the projecting portion 60 and the second contact portion 79b. Therefore, even if the front end portion 53a of the shaft member 53 contacts the first contact portion 79a, the swing member 73a does not swing, and the shaft member 53 resists the biasing force of the first coil spring 54 (see FIG. 4). And pushed into the developing device 3a. Accordingly, the developing roller 29 is close to the photosensitive drum 1a and can develop the electrostatic latent image on the photosensitive drum 1a.

  When the developing device 3a is first removed from the image forming apparatus 200, the engagement claw 35 provided on the lower front side of the developing device 3a by pushing up the lock release lever 37 and the front plate 101 (see FIG. 12 for both). As shown in FIG. 18, when the developing device 3a is pulled out to the upstream side in the insertion direction (arrow A direction), the shaft member 53 maintains the contact state between the tip end portion 53a and the first contact portion 79a. However, the urging force of the first coil spring 54 gradually pops out of the developing device 3a. Accordingly, since the developing roller 29 moves in a direction to retract from the photosensitive drum 1a, the developing roller 29 and the photosensitive drum 1a do not come into contact with each other by the drawing operation of the developing device 3a, and the surface of the photosensitive drum 1a or the developing roller 29 There is no risk of hurting.

  When the drum unit 40a is first removed from the image forming apparatus 200, the engagement claw 45 provided on the lower front side of the drum unit 40a by pushing up the lock release lever 47 and the front plate 101 (both see FIG. 12). As shown in FIG. 19, when the drum unit 40a is pulled out upstream (in the direction of arrow A), the protrusion 60 moves away from the second contact portion 79b. On the other hand, since the urging force of the first coil spring 54 acts on the first contact portion 79a via the shaft member 53, the swing member 73a rotates in the clockwise direction in FIG. Move. As a result, the shaft member 53 gradually protrudes to the outside of the developing device 3a by the urging force of the first coil spring 54 while maintaining the contact state between the distal end portion 53a and the first contact portion 79a.

  Accordingly, since the developing roller 29 moves in the direction of retreating from the photosensitive drum 1a, the developing roller 29 and the photosensitive drum 1a do not come into contact with each other by the pulling operation of the drum unit 40a, and the surface of the photosensitive drum 1a or the developing roller 29 is touched. There is no risk of injury.

  On the other hand, when the developing device 3a is first inserted into the image forming apparatus 200, the swinging of the swinging member 73a in the clockwise direction is not restricted by the protrusion 60 of the drum unit 40a. Therefore, when the developing device 3a is inserted, the swinging member 73a swings clockwise while the tip 53a of the shaft member 53 presses the first contact portion 79a as shown in FIG. When the developing device 3a is completely inserted, the shaft member 53 protrudes outside the developing device 3a. Further, the engaging claw 35 engages with the front plate 101, whereby the developing device 3a is held in the mounted state.

  Thereafter, as the drum unit 40a is inserted, the swinging member 73a swings in the counterclockwise direction of FIG. 19 while the projection 60 presses the second contact portion 79b. As a result, the shaft member 53 is pressed by the first contact portion 79a and pushed into the developing device 3a, and the developing roller 29 gradually approaches the photosensitive drum 1a. When the drum unit 40a is completely inserted, the developing roller 29 approaches the photosensitive drum 1a up to a predetermined distance, and the electrostatic latent image on the photosensitive drum 1a can be developed. Further, the engagement claw 45 is engaged with the front plate 101, whereby the drum unit 40a is held in the mounted state.

  When the drum unit 40a is first inserted into the image forming apparatus 200, the swinging of the swinging member 73a in the clockwise direction is restricted by the protrusion 60 of the drum unit 40a. Therefore, when the developing device 3a is inserted, the tip 53a of the shaft member 53 comes into contact with the first contact portion 79a as shown in FIG. 18, and the shaft member 53 gradually jumps out of the developing device 3a. Therefore, the developing roller 29 gradually approaches the photosensitive drum 1a. When the developing device 3a is completely inserted, the developing roller 29 approaches the photosensitive drum 1a up to a predetermined distance, and the electrostatic latent image on the photosensitive drum 1a can be developed.

  The operation of the swinging member 73a when attaching / detaching the developing device 3a and the drum unit 40a has been described above. However, the operation of the swinging members 73b-73d when attaching / detaching the developing devices 3b-3d and the drum units 40b-40d is quite complete. The same will be explained.

  By using the positioning member 70 of the present embodiment, contact between the developing roller 29 and the photosensitive drum 1a is avoided regardless of the order in which the developing devices 3a to 3d and the drum units 40a to 40d are attached and detached. Therefore, there is no possibility of damaging the surfaces of the photosensitive drum 1a and the developing roller 29.

Further, the pressing load of the shaft member 53 when the developing roller 29 is brought close to the photosensitive drums 1a to 1d is applied when the individual developing devices 3a to 3d or the drum units 40a to 40d are inserted. Therefore, when the retainer 90 (see FIG. 10) is closed, a load is not applied at once, and the operability of the retainer 90 is improved. Further, since the retainer 90 is not likely to be deformed by a load at the time of opening and closing, the positioning accuracy of the drum shafts 1a _{1 to} 1d ₁ is improved, and it is not necessary to increase the rigidity of the retainer 90, thereby simplifying the configuration.

  The individual insertion loads of the developing devices 3a to 3d or the drum units 40a to 40d increase. However, since the insertion load at this time is only the pressing load of the single shaft member 53, the developing devices 3a to 3d or the drum unit 40a. The operability at the time of insertion of ˜40d is not lowered.

  Further, when removing the developing devices 3a to 3d, when the lock release lever 37 (see FIG. 12) on the front side of the developing devices 3a to 3d is pushed up, the engagement between the front plate 101 and the engaging claw 35 is released, The shaft member 53 pops out of the developing devices 3a to 3d by the biasing force of the first coil spring 54. At this time, the developing devices 3a to 3d are moved to the front side of the image forming apparatus 200 by the drag force received from the first contact portion 79a by the shaft member 53 pressing the first contact portions 79a of the swinging members 73b to 73d. Come out a little.

  Further, when removing the drum units 40a to 40d, if the lock release lever 47 (see FIG. 12) on the front side of the drum units 40a to 40d is pushed up, the engagement between the front side plate 101 and the engagement claw 45 is released, and the protrusions The swinging of the swinging member 73a that has been regulated by 60 is allowed. Thereby, the shaft member 53 jumps out of the developing devices 3a to 3d by the urging force of the first coil spring 54. At this time, when the shaft member 53 presses the first contact portion 79a of the swing members 73b to 73d, the swing members 73a to 73d swing in the direction in which the second contact portion 79b moves to the front side. Therefore, the protrusion 60 is pushed by the second contact portion 79b, and the drum units 40a to 40d slightly protrude to the front side of the image forming apparatus 200.

  Accordingly, the operator can grasp and pull out the end portions of the developing devices 3a to 3d or the drum units 40a to 40d that have popped out, and the take-out property of the developing devices 3a to 3d or the drum units 40a to 40d is improved.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, the present invention is not limited to the color printer as shown in FIG. 1, but includes monochrome printers, monochrome and color copiers, digital multifunction peripherals (copiers, facsimiles, scanners, and other functions). The present invention can also be applied to other image forming apparatuses such as “Peripheral”.

  The present invention is applicable to an image forming apparatus including a detachable developing device and an image carrier unit. By utilizing the present invention, it is possible to smoothly and reliably move the developing roller toward or away from the image carrier when the developing device or the image carrier unit is attached or detached. An image forming apparatus excellent in operability in which the body unit can be easily attached and detached can be provided.

1a to 1d Photosensitive drum (image carrier)
3a to 3d Developing device 29 Developing roller 35, 45 Engaging claw (lock mechanism)
37, 47 Unlocking lever (locking mechanism)
40a to 40d Drum unit (image carrier unit)
50 Housing 51 Roller contact / separation mechanism 52a, 52b Arm member 53 Shaft member 53a Tip portion 54 First coil spring (biasing member)
55 Bearing member 56 Second coil spring 70 Positioning member 71 Positioning frame 73a to 73d Swing member 75a to 75d Strut portion 77 Swing fulcrum 79a First contact portion 79b Second contact portion 90 Retainer (image carrier positioning unit)
100 Waste Toner Transport Unit 200 Image Forming Apparatus Pa to Pd Image Forming Unit

Claims (5)

An image carrier having an image carrier on which an electrostatic latent image is formed, and being detachably disposed on the image forming apparatus main body;
A developing device that is disposed so as to be close to or retractable from the image carrier, has a developing roller that supplies toner onto the image carrier, and is detachably disposed adjacent to the image carrier unit;
A positioning member that is disposed on the downstream side in the mounting direction of the developing device and the image carrier unit, and in which a bearing hole into which a rotation shaft of the image carrier is fitted is formed;
A shaft member provided so as to be able to protrude and retract from the downstream side in the mounting direction of the developing device facing the positioning member, and a biasing member that biases the shaft member in a direction protruding from the developing device, A roller contact / separation mechanism that pushes the shaft member into the developing device to bring the developing roller closer to the image carrier and causes the developing roller to retract from the image carrier by projecting the shaft member from the developing device. When,
A lock mechanism capable of individually holding the image carrier unit and the developing device and releasing the holding;
In an image forming apparatus comprising:
The positioning member includes a first contact portion that contacts an end portion of the shaft member protruding from the developing device, a second contact portion that contacts a part of the image carrier unit, and the first contact portion. A swinging member having a swinging fulcrum provided between the contact part and the second contact part is disposed;
In a state where a part of the image carrier unit and the second contact portion are in contact with each other, the swing of the swing member is restricted, and the shaft member is in contact with the first contact portion and the development is performed. While being pushed into the apparatus and part of the image carrier unit and the second contact portion are separated from each other, the swinging member is allowed to swing, and the shaft member is moved by the biasing member . An image forming apparatus protruding from the apparatus.   The swing member is a frame body having an annular shape in plan view, and the first contact portion and the second contact portion are provided at two opposing positions on the frame body, and the first contact portion and the first contact portion are provided. The image forming apparatus according to claim 1, wherein the swing fulcrum is provided at two locations that are substantially equidistant from the two abutting portions. When the holding state of the mounting state of the image carrier unit or the developing device is released by the lock mechanism, the image carrier unit or the developing device protrudes upstream in the mounting direction by the biasing force of the biasing member . 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is characterized in that   A plurality of the image carrier units and the developing devices are provided corresponding to different colors, and a plurality of the swinging members are provided at positions of the positioning members corresponding to the image carrier units and the developing devices. The image forming apparatus according to claim 1, wherein the image forming apparatuses are arranged individually.   5. The image forming apparatus according to claim 4, further comprising an image carrier positioning unit disposed adjacent to the upstream side in the mounting direction of each image carrier unit and each developing device so as to be openable and closable.

Images