JP2015169687A - image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus in which a coupling is surely connected when an image forming unit is attached to an apparatus body and the occurrence of color shift and banding can be suppressed by suppressing rotation unevenness occurring when an image is formed.SOLUTION: The image forming apparatus includes an image forming unit 38 which can be attached and detached to and from the apparatus body, a main body drum coupling 45 which transmits rotational drive to the image forming unit 38, a spring 51 which energizes the main body drum coupling 45 in a thrust direction, and a regulation member 50 which regulates the movement in the radial direction of the main body drum coupling 45. In a standby state where the image forming unit 38 is not attached to the apparatus body, the main body drum coupling 45 is energized to a regulation position where the main body drum coupling 45 can be regulated by the regulation member 50 by the spring 51 and in a set state where the image forming unit 38 is attached to the apparatus body, the main body drum coupling 45 is moved to a retreat position where the main body drum coupling 45 is retreated from the regulation position in the thrust direction.

Description

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

  FIG. 10 is a cross-sectional view around a conventional coupling. FIG. 11 is a perspective view around a conventional coupling. As shown in FIG. 10, as a conventional image forming apparatus, a unit drum coupling 70 of an image forming unit 61 and a main body drum coupling 65 of the apparatus main body are connected to transmit rotation driving of the main body to the photosensitive drum 71. There is something. As shown in FIG. 11, the claw portion of the coupling 65 is engaged with the claw portion of the coupling 70, so that the rotation drive of the drum gear is transmitted to the photosensitive drum 71.

  FIG. 12 is a view on arrow A in FIG. 11 and shows a state in which the coupling 65 and the coupling 70 are engaged with each other. FIG. 12A shows a state where the coupling 70 axial center and the coupling 65 axial center are not displaced (no misalignment). FIG. 12B shows a state in which the coupling 70 axis and the coupling 65 axis are displaced (with misalignment).

  As shown in FIG. 12A, when the coupling 65 rotates, the four claw portions formed on the coupling 65 mesh with the four claw portions formed on the coupling 70. , Loads F1, F2, F3, and F4 are generated. The resultant force of the loads F1, F2, F3, and F4 is F1-F3 = 0 in the X direction and F4-F2 = 0 in the Y direction, and no force that deforms in the X direction and the Y direction is generated.

  As shown in FIG. 12B, when the axial center of the coupling 70 is deviated from the axial center of the coupling 65 by Δy in the Y direction, only the load F4 is generated when the claw portion is engaged at only one place, Loads F1, F2, and F3 are not generated. At this time, when the coupling rotates, the coupling 70 is deformed in a direction to reduce Δy, that is, a direction to reduce the misalignment by the aligning force. Similarly, the coupling 65 is deformed in a direction to reduce the misalignment. For this reason, stress is generated in a region (stress generating portion) where the drum gear shaft shown in FIG. 10 is supported by the bearing, and uneven speed (uneven rotation) occurs in the rotation of the photosensitive drum 71. As a result, image defects such as color misregistration and banding occur.

  Therefore, in the image forming apparatus described in Patent Document 1, as shown in FIG. 13, the main body drum coupling 65 transmits the rotational drive of the gear 62 to the unit drum coupling 70 of the image forming unit 61. The main body drum coupling 65 is arranged to be movable without fixing the movement in the radial direction with a bearing or the like. As a result, even if a load that moves in the radial direction is generated in the coupling 65 when it is rotationally driven, the rotational drive can be transmitted to the photosensitive drum 71 without causing stress due to deformation.

JP-A-2005-241946

  However, as shown in FIG. 14, when the coupling 65 is tilted when the image forming unit 61 is attached to the apparatus main body, the axis of the tip of the coupling 65 is displaced from the axis of the coupling 70. At this time, the coupling 65 cannot be inserted into the recess 72 formed in the coupling 70 shown in FIG. 13, and the coupling 65 and the coupling 70 cannot be connected.

  Therefore, as shown in FIG. 15, a restricting portion 76 that restricts the movement of the coupling 65 in the radial direction is provided. Accordingly, the inclination of the coupling 65 or the movement in the radial direction can be restricted, and the coupling 65 and the coupling 70 can be reliably connected when the image forming unit 61 is mounted on the apparatus main body.

  However, when driven with the shaft center of the coupling 65 and the shaft center of the coupling 70 shifted, the coupling 65 tends to move in a direction to reduce the shift of the shaft center. For this reason, stress is generated in the restricting portion 76 that is in contact, causing uneven rotation, resulting in image defects such as color misregistration and banding.

  Therefore, the present invention can reliably connect the coupling when the image forming unit is mounted to the apparatus main body, and can suppress uneven rotation that occurs during image formation, thereby suppressing the occurrence of color misregistration and banding. An object is to provide an image forming apparatus.

  In order to solve the above problems, a typical configuration of an image forming apparatus according to the present invention includes a driven unit, a cartridge that can be attached to and detached from the apparatus main body, and a cartridge that is provided in the apparatus main body and rotates to the driven unit. A main body drive connecting member that transmits driving; a biasing member that biases the main body drive connecting member in a thrust direction; and a regulating member that restricts movement of the main body drive connecting member in a radial direction, In a standby state in which the cartridge is not attached to the apparatus main body, the main body drive connecting member is urged by the urging member to a restriction position that can be restricted by the restriction member in the thrust direction. In the set state of being mounted on the main body, the main body drive connecting member moves from the restricting position to a retracted position retracted in a thrust direction.

  According to the present invention, it is possible to reliably connect the coupling when the image forming unit is mounted on the apparatus main body, and it is possible to suppress the rotation unevenness generated at the time of image formation and suppress the occurrence of color misregistration and banding. it can.

1 is a configuration diagram of an image forming apparatus according to an embodiment. It is a perspective view of the coupling which connects the drum drive which concerns on embodiment. It is sectional drawing around the coupling in the standby state which concerns on embodiment. It is an enlarged view of the a part of FIG. It is sectional drawing around the coupling in the structure without the limitation member as a comparative example. It is sectional drawing around the coupling in the set state which concerns on embodiment. It is an enlarged view of the b section of FIG. FIG. 5 is a cross-sectional view around the coupling illustrating the operation when the image forming unit according to the embodiment is removed from the apparatus main body. FIG. 3 is a cross-sectional view around the coupling after the image forming unit according to the embodiment is removed from the apparatus main body. It is sectional drawing around the conventional coupling. It is a perspective view around the conventional coupling. It is A arrow directional view of FIG. It is sectional drawing around the conventional coupling. It is sectional drawing which showed a mode that the conventional coupling front-end | tip inclined. It is sectional drawing of the structure which controls the inclination of the conventional coupling front-end | tip.

  An embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an image forming apparatus according to the present embodiment. As shown in FIG. 1, in the image forming apparatus 100 of the present embodiment, the photosensitive drum (image carrier, driven part) 1 (1Y, 1M, 1C, 1K) is charged by charging means 31Y to 31K. The Then, laser light corresponding to the image information is exposed by the exposure means 32Y to 32K, and an electrostatic latent image is formed.

  The formed electrostatic latent image is developed as a toner image of each color using toner of each color of yellow Y, magenta M, cyan C, and black K by developing rollers 33Y to 33K. The developed toner image is primarily transferred to the intermediate transfer belt 3 by the primary transfer rollers 2Y to 2K. The toner image primarily transferred to the intermediate transfer belt 3 is secondarily transferred to the sheet T by the secondary transfer roller 26. The sheet T on which the toner image is secondarily transferred is heated and pressurized by the fixing device 35 to fix the toner image, and is discharged outside the apparatus main body.

  The transfer residual toner remaining on the photosensitive drums 1Y to 1K after the primary transfer is cleaned by the cleaning members 34Y to 34K. The transfer residual toner remaining on the intermediate transfer belt 3 after the secondary transfer is cleaned by the belt cleaning member 18.

(Drive configuration of photosensitive drums 1Y to 1K)
FIG. 2 shows a state in which a detachable image forming unit (cartridge) 38 (38Y to 38K) is mounted on the apparatus main body 100a. At this time, the main body drum coupling (main body drive connecting member) 45 (45Y to 45K) of the drive unit 39 (39Y to 39K) and the unit drum coupling 46 (46Y to 46K) of the image forming unit 38 are connected.

  As shown in FIG. 2, when a motor (not shown) of the drive unit 39 is rotationally driven, the photosensitive drum gear 43 (43Y to 43K) is rotationally driven via a gear (not shown). The rotational drive of the photosensitive drum gear 43 is transmitted to the photosensitive drum 1 through the photosensitive drum gear shaft 44 (44Y to 44K), the couplings 45 and 46, and the photosensitive drum shaft 47 (47Y to 47K).

(Position of the main body drum coupling 45 in the standby state)
FIG. 3 is a sectional view around the main body drum coupling 45 in the standby state. The standby state refers to a state before the image forming unit 38 is mounted on the apparatus main body. As shown in FIG. 3, the main body drum coupling 45 is attached to the drum gear shaft 44 so as to be movable in the thrust direction. The coupling 45 is biased by a spring (biasing member) 51 and is brought into contact with a contact portion 50c (see FIG. 4) of the regulating member 50, so that the position in the thrust direction is fixed. The spring 51 is seated on an E-ring 52 attached to the drum gear shaft 44.

  As shown in FIG. 4, the coupling 45 is formed in a cylindrical shape and has an annular rib (projection) 45a having a diameter φD1 on the outer periphery. The restricting member 50 is formed in a cylindrical shape, and has a restricting portion 50 a having an inner diameter φD <b> 2 protruding from the inner periphery of the restricting member 50. In the standby state, the rib 45a abuts on the abutment portion 50c and is located in a region A (regulation position) where the restriction portion 50a is formed in the thrust direction.

  The restriction position is a position where the main body drum coupling 45 can be restricted by the restriction member 50. When the coupling 45 moves in the radial direction, the rib 45a comes into contact with the restricting portion 50a, thereby suppressing the coupling 45 from moving in the radial direction by a predetermined distance or more. With reference to the position where the axis 45b of the coupling 45 is located at the position coincident with the axis 50b of the regulating member 50, the movement range of the coupling 45 is-(D2-D1) / 2-+ (D2-D1). ) / 2.

  FIG. 5 is a cross-sectional view around the coupling having a configuration without the regulating member 50 as a comparative example. As shown in FIG. 5, the position of the main body drum coupling 45 moves with the bearing 55 as a fulcrum via the drum gear shaft 44, and the position of the coupling 45 in the radial direction is not fixed. Therefore, in the standby state, the shaft center 45b of the coupling 45 and the shaft center 46b of the unit drum coupling 46 are displaced, and the coupling 46 and the coupling 45 cannot be connected even when the image forming unit 38 is mounted on the apparatus main body 100a. .

  Therefore, in the present embodiment, the coupling 45 is reliably coupled to the coupling 45 when the image forming unit 38 is mounted by suppressing the coupling 45 from moving by a predetermined distance in the radial direction by the regulating member 50. I can do it.

(Position of the main body drum coupling 45 in the set state)
FIG. 6 is a cross-sectional view around the unit drum coupling 46 and the main body drum coupling 45 in the set state. The set state means a state in which the image forming unit 38 is mounted on the apparatus main body 100a.

  As shown in FIG. 6, when the image forming unit 38 is mounted on the apparatus main body 100a, the coupling 46 abuts against the coupling 45, so that the coupling 45 resists the biasing force of the spring 51 in the thrust direction. Pushed in. And the coupling 45 moves so that the shaft center 45b may approach the shaft center 46b because the alignment shaft 49 provided in the front-end | tip of the coupling 45 fits into the recessed part 46a of the coupling 46. As shown in FIG.

  At this time, as shown in FIG. 7, the rib 45a has moved to the retracted position retracted from the region A (regulatory position) in the thrust direction. The inner diameter of the restricting member 50 at the position retracted from the region A is larger than the inner diameter of the restricting portion 50a. For this reason, even if the coupling 45 moves in the radial direction in the set state, the coupling 45 does not contact the regulating member 50. As a result, rotational fluctuations (unevenness of rotation) when the photosensitive drum 1 is rotated caused by contact between the coupling 45 and the regulating member 50 are suppressed, and rotational driving is stably transmitted to the photosensitive drum 1. be able to. Thereby, image defects such as color misregistration and banding can be suppressed.

(Movement of the main body drum coupling 45 when the image forming unit 38 is removed from the apparatus main body 100a)
FIG. 8 is a cross-sectional view around the coupling illustrating the operation when the image forming unit 38 is detached from the apparatus main body 100a. As shown in FIG. 8, when the image forming unit 38 is removed from the apparatus main body 100a, the coupling 46 moves in the thrust direction (arrow direction), and the coupling 45 also moves in the thrust direction (arrow direction) by the biasing force of the spring 51. Moving.

  At this time, when the axis 45b is inclined, the rib 45a abuts on the tapered portion 50d provided on the side surface of the restricting portion 50a and slides along the tapered portion 50d, as shown in FIG. The rib 45a returns to the region A and enters a standby state. Thereby, even when the image forming unit 38 is removed from the apparatus main body 100a, it is possible to prevent the axis 45b from being inclined, and to reliably return to the standby state in which the coupling 46 and the coupling 45 can be reliably connected. be able to.

  In this embodiment, the photosensitive drum 1 has been described as an example of the driven part. However, the present invention is not limited to such a configuration, and the intermediate transfer belt 3 and the developing roller 33 may be used as the driven part. Good.

A ... area T ... sheet 1 ... photosensitive drum (image carrier, driven part)
3 ... Intermediate transfer belt (driven part)
33 ... Developing roller (driven part)
38 ... Image forming unit (cartridge)
39... Drive unit 43... Photoconductor drum gear 44... Photoconductor drum gear shaft 45... Main body drum coupling (main body drive connecting member)
45a ... rib (protrusion)
45b, 46b, 50b ... axis 46 ... unit drum coupling 46a ... recess 47 ... photoconductor drum shaft 49 ... alignment shaft 50 ... regulating member 50a ... regulating part 50c ... contact part 50d ... taper part 51 ... spring (attached) Force member)
52... E ring 55... Bearing 100... Image forming apparatus 100 a.

Claims (7)

A cartridge having a driven part and detachable from the apparatus main body;
A main body drive connecting member that is provided in the apparatus main body and transmits rotational driving to the driven part;
A biasing member that biases the main body drive connecting member in a thrust direction;
A regulating member that regulates movement of the main body drive connecting member in the radial direction,
In a standby state in which the cartridge is not attached to the apparatus main body, in the thrust direction, the main body drive connecting member is biased to a restriction position that can be restricted by the restriction member by the biasing member,
In the set state in which the cartridge is mounted on the apparatus main body, the main body drive connecting member moves from the restriction position to a retracted position retracted in a thrust direction.
The main body drive connecting member is formed in a cylindrical shape, and has an annular protrusion on the outer periphery,
The restricting member is formed in a cylindrical shape, and has a restricting portion protruding from the inner periphery of the restricting member,
2. The movement of the main body drive connecting member in the radial direction is restricted by the protrusion coming into contact with the restricting portion when the main body drive connecting member moves in the radial direction. Image forming apparatus.
When the cartridge is mounted on the apparatus main body, the main body drive connecting member is pushed against the urging force of the urging member by the cartridge and moves from the restriction position to the retracted position. The image forming apparatus according to claim 1.
A taper portion is formed on the side surface of the restriction portion,
The image forming apparatus according to claim 2, wherein when the main body drive connecting member moves from the retracted position to the restricting position, the protrusion moves along the tapered portion.
The image forming apparatus according to claim 1, wherein the driven portion is an image carrier.
The image forming apparatus according to claim 1, wherein the driven portion is a developing roller.
  The image forming apparatus according to claim 1, wherein the driven portion is an intermediate transfer belt.

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