JP2005157186A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology, capable of making a photoreceptor away from a transfer body with a simple configuration upon jam removal to effectively prevent the photoreceptor from damages and surely reducing the impact caused by collisions between a regulation member of the development unit side and the photoreceptor. <P>SOLUTION: Only by removing the development unit 12 from a prescribed position in an image forming apparatus body 11 at jam processing, a transfer body moving means 28 allows the transfer roller 5 to move separated from the photoreceptor 4 coupled to the movement of the development unit 12. When the development unit 12 is loaded to a prescribed position in the image forming apparatus body 11, a slider spring 31 of the transfer body moving means 28 reduces the impact caused by the collision between the regulation member 37 of the development unit 12 and the photoreceptor 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile.

  Conventionally known image forming apparatuses such as electrophotographic copying machines generally irradiate the surface of a photoconductor uniformly charged by a charger with a laser beam using an exposure device, thereby forming an electrostatic latent image on the surface of the photoconductor. The developer is supplied from the developing unit to the surface of the photosensitive member on which the electrostatic latent image is formed, and the electrostatic latent image on the surface of the photosensitive member is visualized as a toner image. Then, the toner image formed on the surface of the photoreceptor is transferred onto a sheet-like transfer material (copy paper, OHP film, etc.) by a transfer body such as a transfer roller. Thereafter, the developer remaining on the photoreceptor is removed by a cleaning device. Next, such an image forming apparatus feeds the transfer material onto which the toner image has been transferred to the fixing unit, fixes the toner image on the surface of the transfer material, and then discharges the fixed transfer material to a discharge tray or the like. To load.

  FIGS. 8 to 9 show an example of such an image forming apparatus 100, in which a photosensitive unit 101 including a charger, a photosensitive member, a cleaning device, and the like is fixed to the image forming apparatus main body 102 side. In contrast, the developing unit 103 is detachably attached to the image forming apparatus main body 102. FIG. 8 shows a state in which the developing unit 103 is attached to a predetermined position in the image forming apparatus main body 102. FIG. 9 is a diagram illustrating a state in which the developing unit 103 is removed from a predetermined position in the image forming apparatus main body 102.

  In such an image forming apparatus 100, when a jam (paper jam) occurs between the photosensitive member 104 and the transfer member 105, the user forms an image only on the developing unit 103 as shown in FIGS. After removal from the apparatus main body 102, the transfer material 106 between the photoconductor 104 and the transfer body 105 is to be pulled out. However, the photosensitive member 104 and the transfer member 105 are in close contact with each other so as to form a nip, or a very narrow gap is formed between them, and the transfer material 106 is sandwiched between them. Therefore, when the user tries to pull out the transfer material 106 in the direction opposite to the transfer material conveyance direction, the surface of the photosensitive member 104 and the transfer material 105 and the transfer material are removed. 106 is rubbed with a strong force, and the surface of the photosensitive member 104 or the transfer member 105 may be damaged.

  In order to avoid such a problem of the conventional image forming apparatus 100, even when the developing unit 103 is removed from the image forming apparatus main body 102, the user cannot touch the jammed transfer material 106. It is conceivable that a cover 107 is attached on the upstream side in the transfer material conveyance direction with respect to the portion where the photosensitive member 104 and the transfer member 105 are opposed to each other, thereby making it difficult for the user to touch the jammed transfer material 106 (see FIG. 12). However, even with such a contrivance, it is difficult to arrange the cover 107 as close as possible to the photoconductor 104 due to layout reasons such as the development unit 103 having to be arranged next to the photoconductor 104. For this reason, it is difficult to reliably prevent the user from touching the jammed transfer material 106.

  Therefore, in order to prevent the photosensitive member 104 from being damaged during such a jam processing, the transfer member 105 is separated from the photosensitive member 104, and a sufficient gap (transfer) is formed between the transfer member 105 and the photosensitive member 104. A technique has been devised in which a gap larger than the thickness of the material is formed.

  For example, in the technique of Patent Document 1, when the front cover of the image forming apparatus main body is opened, a release lever linked to the front cover is interlocked, and a roller rolling contact release mechanism connected to the release lever serves as a transfer body. The transfer roller is separated from the photoconductor.

  In the technique of Patent Document 2, the developing unit and the transfer member are linked by a link mechanism, and the link mechanism is operated to separate the developing unit from the photosensitive member and to separate the transfer member from the photosensitive member. It has become.

  Further, instead of separating the transfer member from the photosensitive member as in the above-mentioned Patent Documents 1 and 2, the photosensitive member unit and the developing unit are integrally separated from the transfer roller as the transfer member attached to the image forming apparatus main body. When the photosensitive unit and the developing unit are mounted at a predetermined position (image forming position) in the main body of the image forming apparatus, the photosensitive unit unit is exposed from a direction perpendicular to the direction along the axis of the transfer roller. Japanese Patent Application Laid-Open No. H10-228473 discloses a technique in which the surface of the photosensitive drum is not damaged by bringing the body drum into contact therewith.

JP 7-191557 A JP-A-4-331960 JP-A-1-229270

  However, in the technique of Patent Document 1, in the image forming apparatus in which the developing unit is detachable from the main body of the image forming apparatus, when the jam processing is performed with the developing unit removed, the transfer body must be opened unless the front cover is opened. There is a problem that it cannot be separated from the photoconductor, and an extra operation of opening the front cover is required.

  Moreover, since the technique of patent document 2 requires a complicated link mechanism, while the whole structure is complicated, the space for accommodating a complicated link mechanism is needed, and the whole structure becomes large in size. Have.

  In the technique of Patent Document 3, the developing unit and the photosensitive unit must be integrally attached to and detached from the main body of the image forming apparatus. If the developing unit and the photosensitive unit are integrated, the outer shape becomes large and the weight is increased. Therefore, compared with the case where only the developing unit is attached to and detached from the main body of the image forming apparatus, there is a problem in that the burden on the user during the jam processing is increased.

  In addition, in a conventional image forming apparatus, a developer is allowed to fly from the developing roller toward the surface of the photosensitive member while maintaining a certain distance (developing gap) between the surface of the photosensitive member and the outer peripheral surface of the developing roller. There are things. In the image forming apparatus adopting such a configuration, in order to keep a proper developing gap between the surface of the photosensitive member and the developing roller, as shown in FIGS. 13 and 14, roller shafts 36 at both ends of the developing roller 13 are used. A restricting member 37 having a substantially disc shape having a diameter larger than that of the developing roller 13 is installed on the surface of the photosensitive member 104. As a result, when the developing unit 103 is attached to the image forming apparatus main body 102 (see FIG. 8), the regulating member 37 on the developing unit 103 side collides with the photoconductor 104 vigorously. Due to the impact of the collision with the photosensitive member 104, the portion of the photosensitive member 104 that has collided with the regulating member 37 is deformed, and the developing gap between the photosensitive member 104 and the developing roller 13 becomes inadequate, which may cause image defects. In such a case, attempts have been made to devise the shape and structure of the guide rail 108 that guides the developing unit 103 to a predetermined position in the image forming apparatus main body 102, but sufficient effects have not been obtained (FIG. 12). reference).

  Therefore, according to the present invention, it is possible to separate the photosensitive member and the transfer member with a simple configuration at the time of jam processing, and it is possible to effectively prevent the photosensitive member from being damaged. To provide a technology capable of reliably mitigating the impact caused by a collision.

  The invention according to claim 1 is a photosensitive member having an electrostatic latent image formed on a surface thereof, a developing unit that supplies a developer to the surface of the photosensitive member to visualize the electrostatic latent image as a toner image, and the photosensitive member. A transfer body for transferring the toner image formed on the surface of the body to a transfer material, the development unit being attachable to and detachable from a development position facing the photoconductor, and a transfer for facing the transfer body to the photoconductor The present invention relates to an image forming apparatus which can be moved by a transfer body moving means between a position and a retracted position sufficiently separated from the photoreceptor. The transfer member moving means of the image forming apparatus is disposed at (a) a transfer member holding spring for holding the transfer member at the transfer position with an elastic force, and (b) at a position not in contact with the photosensitive member. A slider that slides in a direction substantially along the attaching / detaching direction of the developing unit, and (c) when the developing unit approaches the developing position to a predetermined position when the developing unit is mounted at the developing position, A slider spring that elastically abuts the tip of the slider against the developing unit. In the image forming apparatus, when the developing unit is moved from the developing position, the slider is urged by the slider spring until the slider reaches the predetermined position and elastically pushes against the developing unit. The slider slides in the applied state, and the slider pushes and contracts the transfer holding spring to move the transfer body to the retracted position.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the developing unit is positioned at a developing position by causing a part of the developing unit to abut against the photosensitive member.

  In the present invention, at the time of jam processing, the transfer body moving means moves the transfer body away from the photoconductor in conjunction with the movement of the development unit only by removing the developing unit from a predetermined position in the image forming apparatus main body. Therefore, when the jamming process is performed with the developing unit removed, the surface of the photosensitive member and the transfer member are not damaged by the frictional contact with the transfer material.

  Further, according to the present invention, when the developing unit is mounted at a predetermined position in the main body of the image forming apparatus, the slider spring of the transfer member moving means can relieve the impact of the collision between the regulating member of the developing unit and the photosensitive member. Therefore, the photosensitive member is not damaged by the collision with the regulating member of the developing unit, the developing gap can be properly maintained for a long period of time, and high-precision image formation can be performed over a long period of time.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1 to 2 show a schematic configuration of an image forming apparatus 1 according to an embodiment of the present invention. As shown in these drawings, in the image forming apparatus 1 according to the present embodiment, a sheet-like transfer material (paper such as copy paper or plastic film such as an OHP film) 3 fed from a paper feed tray 2 is a drum. Then, the toner image on the surface of the photosensitive member 4 is transferred to the transfer material 3. The transfer material 3 onto which the toner image has been transferred is sent to the fixing means 7 along the transfer material conveyance path 6 and is heated and pressurized by the fixing means 7 to fix the toner image. It is supposed to be discharged to the top.

  The photoconductor 4 constitutes a photoconductor unit 10 together with a charging device (not shown) that uniformly charges the surface of the photoconductor 4 and a cleaning device (not shown) that removes toner adhering to the surface of the photoconductor 4 after transfer. The image forming apparatus main body 11 is fixed.

  Further, a developing unit 12 is disposed so as to face the photoconductor 4. As shown in FIG. 4, the developing unit 12 has a predetermined position in the image forming apparatus main body 11 such that a gap dimension (developing gap) d between the developing roller 13 and the surface of the photoreceptor 4 becomes a predetermined dimension. Is detachably attached. Then, the developing unit 12 causes the developer to fly from the developing roller 13 toward the surface of the photoconductor 4 on which the electrostatic latent image is formed by the exposure device 14, and the electrostatic latent image on the surface of the photoconductor 4 is used as a toner image. It is designed to be visualized. As shown in FIG. 2, the developing unit 12 that functions in this manner opens the upper cover 15 at the upper right portion in the drawing and the side cover 16 at the upper right portion in the drawing, and externally opens from the opening portion 17 of the image forming apparatus main body 11. In addition, the image forming apparatus main body 11 can be attached to a predetermined position through the opening 17 of the image forming apparatus main body 11 from the outside.

  As shown in FIG. 3, the transfer roller 5 is supported by a bearing member 21 so that the shafts 20 at both ends in the axial direction are rotatably supported in a transfer roller housing 18 having a substantially rectangular cross section that opens toward the photosensitive member 4. Has been. The bearing member 21 that rotatably supports the transfer roller 5 is elastically supported by a transfer body holding spring 23 with respect to the bottom surface 22 of the transfer roller housing 18. The transfer roller 5 is pressed against the photoconductor 4 by the spring force of the transfer body holding spring 23 acting via the bearing member 21 to form a nip P that sandwiches the transfer material at the contact portion with the photoconductor 4. doing.

  Here, as shown in FIG. 3, the bearing member 21 is guided by a guide member 25 positioned along the side surface 24 of the transfer roller housing 18 so as to move up and down, and a coil-shaped transfer body holding spring. A spring engagement pin 26 to be inserted into the upper end portion of 23 is formed so as to protrude downward. A spring mounting pin 27 protrudes from the bottom surface 22 of the transfer roller housing 18 so as to face the spring engaging pin 26 of the bearing member 21. The lower end portion of the transfer body holding spring 23 is fitted to the spring mounting pin 27.

  The transfer body holding spring 23 is a coil spring made of a conductive metal, and supports the bearing member 21 in a compressed state so that the transfer roller 5 can be pressed against the photoconductor 4 with a predetermined pressure during transfer. It is supposed to be. A transfer voltage supplied from a power supply unit (not shown) is supplied to the transfer roller 5 through the transfer body holding spring 23 and the bearing member 21.

  4 to 7 are diagrams used to describe the transfer member moving unit 28 for bringing the transfer roller 5 of the image forming apparatus 1 into contact with or away from the photosensitive member 4. It is a figure which simplifies and shows the portion to be arranged typically. As shown in these drawings, the transfer moving means 28 is located at the shaft end portions of the photosensitive member 4 and the transfer roller 5 and obstructs the transfer material from being conveyed along the transfer material conveyance path 6. Are arranged at both shaft end portions of the photosensitive member 4 and at both shaft end portions of the transfer roller 5, respectively.

  As shown in FIGS. 4 to 7, the transfer body moving means 28 moves the transfer roller 5 up and down, and the transfer position at which the transfer roller 5 contacts the photoconductor 4 (FIGS. 4 and 6). , And FIG. 7) and the transfer roller 5 is moved (moved up and down) to a retracted position (see FIG. 5) sufficiently separated from the photosensitive member 4. The transfer body moving means 28 includes the above-described transfer body holding spring 23, a slider 30, and a slider spring 31.

  Among these, the guide frame 32a on the image forming apparatus main body 11 side is arranged so that the slider 30 can slide in a direction substantially along the transfer material conveyance direction and also in a direction substantially along the mounting direction of the developing unit 12. Guided at 32b. One end of the slider 30 is urged toward the upstream side in the transfer material conveyance direction by a slider spring 31. Further, when the developing unit 12 is mounted at a predetermined position in the image forming apparatus main body 11, the slider 30 has a shaft engaging groove 33 that engages the shaft 20 of the transfer roller 5 on the lower surface 34 side facing the transfer roller 5. Is formed. In addition, when the shaft 20 of the transfer roller 5 is engaged with the shaft engaging groove 33, the slider 30 has a slight gap between the shaft engaging groove 33 and the shaft 20 of the transfer roller 5. The transfer roller 5 can be brought into contact with the photoconductor 4 by the spring force of the transfer body holding spring 23.

  As shown in FIG. 5, when the developing unit 12 is removed from a predetermined position (developing position) in the image forming apparatus main body 11 (see FIG. 2), the slider 30 is moved in the transfer material conveyance direction by the spring force of the slider spring 31. As a result of the sliding movement, the engagement between the shaft engagement groove 33 and the shaft 20 is released, and the lower surface 34 without the shaft engagement groove 33 holds the shaft 20 of the transfer roller 5 by the slide movement. It can be pushed down against the spring force of the spring 23. The slider 30 moves to a predetermined position where it is stopped by a stopper (not shown) or a predetermined position where the slider spring 31 is fully extended. One end of the slider spring 31 is supported on the image forming apparatus main body 11 side, and the other end is in contact with the slider 30.

  The developing unit 12 is mounted in the image forming apparatus main body 11 from the state of FIG. 5 to the state of FIG. 4, and when the developing unit 12 approaches a predetermined position (developing position) in the image forming apparatus main body (FIGS. 1 and 2), the front end 35a of the housing 35 of the developing unit 12 contacts the front end 30a of the slider 30, and the housing 35 of the developing unit 12 compresses the slider spring 31 to move the slider 30 downstream in the transfer material conveyance direction. When the shaft engagement groove 33 of the slider 30 is engaged with the shaft 20 at the shaft end of the transfer roller 5, the transfer body holding spring 23 biases the transfer roller 5 toward the photoreceptor 4 via the bearing member 21. However, the transfer roller 5 and the photosensitive member 4 come into contact with each other by the spring force of the transfer member holding spring 23 (see FIG. 3).

  As shown in FIGS. 13 and 14, the developing roller 13 of the developing unit 12 is provided with a disc-shaped regulating member 37 having a larger diameter than the developing roller 13 on the roller shafts 36 at both ends thereof. When 12 is mounted at a predetermined position (development position) in the image forming apparatus main body 11 (see FIG. 4), the regulating member 37 comes into contact with the surface of the photoconductor 4, and the surface of the photoconductor 4 and the surface of the developing roller 13 A gap (development gap) d having a predetermined dimension is formed between the two.

  Here, when the developing unit 12 is mounted in the image forming apparatus main body 11 (see FIG. 5), before the developing unit 12 reaches a predetermined position (developing position) in the image forming apparatus main body 11, the slider spring 31 is moved. The tip end 35a of the housing 35 of the developing unit 12 comes into contact with the tip end 30a of the slider 30 pressed by the spring force, and the developing unit 12 is set at a predetermined position while pushing and shrinking the slider spring 31. Therefore, the impact between the regulating member 37 attached to both ends in the axial direction of the developing roller 13 and the photosensitive member 4 is reduced by the elastic deformation of the slider spring 31.

  As described above, the image forming apparatus 1 according to the present embodiment moves the developing unit 12 from the state shown in FIGS. 1 and 4 to the state shown in FIGS. By simply removing it from the image forming apparatus main body 11, the slider 30 of the transfer member moving means 28 is slid by the spring force of the slider spring 31 to push down the transfer roller 5 against the spring force of the transfer member holding spring 23, and the photosensitive member. A sufficient gap (a gap larger than the thickness of the transfer material 3) is formed between the transfer roller 4 and the transfer roller 5. Therefore, even if the user puts a hand in the space formed by removing the developing unit 12 and pulls out the transfer material 3, the surface of the photoreceptor 4 and the surface of the transfer roller 5 may be damaged by frictional contact with the transfer material 3. Absent.

  Further, as described above, in the image forming apparatus 1 of the present embodiment, when the developing unit 12 is mounted at a predetermined position of the image forming apparatus main body 11, the regulating member 37 of the developing unit 12 contacts the photoconductor 4. The slider 30 comes into contact with the housing 35 of the developing unit 12 from the front, and the impact when the developing unit 12 is mounted at a predetermined position in the image forming apparatus main body 11 can be buffered by the slider spring 31. As a result, the image forming apparatus 1 according to the present embodiment comes into contact with the photosensitive member 4 with the restricting member 37 of the developing unit 12 being buffered, and the photosensitive member 4 is damaged by the restricting member 37 of the developing unit 12. Therefore, the developing gap d between the photosensitive member 4 and the developing roller 13 can be maintained properly for a long period of time, and high-quality image formation can be performed over a long period of time.

  Further, the image forming apparatus 1 of the present embodiment does not require a complicated link mechanism as in the prior art, and the transfer body moving means 28 having a simple configuration including the slider 30, the slider spring 31, and the transfer body holding spring 23. As a result, the transfer roller 5 can be separated from the photoconductor 4, so that the overall structure can be reduced in size and weight, and the cost can be reduced.

  In this embodiment, the drum-shaped photoconductor 4 is exemplified as the photoconductor, but the present invention is not limited to this and can be applied to a belt-shaped photoconductor.

  In the present embodiment, the mode in which the transfer roller 5 is pressed against the photoconductor 4 is exemplified. However, the present invention is not limited to this. The configuration is such that a slight gap is generated between the photoconductor 4 and the transfer roller 5. Can also be applied.

  The present invention can be widely applied to an electrophotographic copying machine, a printer, a facsimile, and an image forming apparatus as a composite machine of these.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a state where a developing unit of the image forming apparatus illustrated in FIG. 1 is removed. FIG. 2 is an enlarged detailed view showing a photoconductor and a transfer body of the image forming apparatus of FIG. 1. FIG. 2 is a configuration diagram of a transfer member moving unit when a developing unit of the image forming apparatus in FIG. 1 is in a developing position. FIG. 2 is a configuration diagram of a transfer member moving unit when the developing unit of the image forming apparatus in FIG. 1 is located at a position separated from a developing position. FIG. 3 is a partial external perspective view of the image forming apparatus with a bearing member and a guide frame omitted, and is an external perspective view of a transfer body moving unit when a developing unit is in a developing position. FIG. 7 is an external perspective view of a transfer body moving unit when the viewing direction is changed from FIG. 6. FIG. 2 is an external perspective view of the image forming apparatus, and is an external perspective view when the developing unit is in a developing position. FIG. 2 is an external perspective view of the image forming apparatus, and is an external perspective view when the developing unit is located at a position separated from the developing position. FIG. 3 is a partial external perspective view of the image forming apparatus showing a photoconductor and a transfer body with the developing unit removed. FIG. 2 is a schematic configuration diagram of an image forming apparatus showing a state in which a developing unit is removed and jammed. It is a schematic block diagram of the image forming apparatus which shows the fault solution means at the time of the conventional jam processing. 2 is an external perspective view showing a relationship between a photoconductor and a developing roller. FIG. FIG. 2 is an external perspective view showing structures of end portions of a photoconductor and a developing roller.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 3 ... Transfer material, 4 ... Photoconductor, 5 ... Transfer roller (transfer body), 6 ... Transfer material conveyance path, 12 ... Development unit, 23 ... Transfer body holding spring , 28 ... transfer member moving means, 30 ... slider, 30 a ... tip, 31 ... slider spring, 37 ... regulating member (part)

Claims (2)

A photosensitive member having an electrostatic latent image formed on the surface, a developing unit for supplying a developer to the surface of the photosensitive member to visualize the electrostatic latent image as a toner image, and a surface formed on the surface of the photosensitive member. A transfer body for transferring the toner image to a transfer material,
The developing unit can be attached to and detached from a developing position facing the photoconductor, and the transfer body can be moved by a transfer body moving means between a transfer position facing the photoconductor and a retracted position sufficiently separated from the photoconductor. In the image forming apparatus which is
The transfer body moving means includes:
A transfer body holding spring for holding the transfer body at the transfer position with an elastic force;
A slider that is arranged at a position not in contact with the photosensitive member and slides in a direction substantially along the attaching / detaching direction of the developing unit;
A slider spring that elastically abuts the tip of the slider against the developing unit when the developing unit approaches the developing position when the developing unit is mounted at the developing position;
When the developing unit is moved from the developing position, the slider is urged by the slider spring and slid in a state of being elastically abutted against the developing unit until the slider reaches the predetermined position. The image forming apparatus, wherein the slider pushes and contracts the transfer holding spring to move the transfer body to the retracted position.   The image forming apparatus according to claim 1, wherein the developing unit is positioned at a developing position by causing a part of the developing unit to abut against the photoconductor.

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