JP4880385B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a drum unit including a photosensitive drum, and a developing unit including a developing roller supported substantially parallel to the photosensitive drum so as to be close to the photosensitive drum and capable of supplying a developer to the photosensitive drum. Are respectively slidable along the rotation axis direction of the photosensitive drum with respect to the main body of the apparatus so as to be freely insertable / removable, and the developing roller is positioned close to the photosensitive drum. In particular, the present invention relates to an image forming apparatus that can be switched between a proximity posture capable of supplying a developer to the photosensitive drum and a separation posture separated from the photosensitive drum.

  In the conventional image forming apparatus, a spring that moves and urges the developing roller of the developing unit attached to the apparatus main body toward the photosensitive drum side is in a biased state in which a biasing force is applied to the developing roller. By switching to a bias release state in which no force is applied, the developing roller is positioned close to the photosensitive drum and can be supplied with developer, and separated from the photosensitive drum. It is provided so that it can be switched to a separated posture (see, for example, Patent Document 1).

JP 2004-264519 A

For this reason, it is necessary to separately perform an operation for inserting / removing the developing unit with respect to the apparatus main body and an operation for switching the posture of the developing roller between the proximity posture and the separation posture. May also occur.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus in which the posture of the developing roller can be switched between the proximity posture and the separation posture with good operability and the possibility of erroneous operation is reduced. And

A first characteristic configuration of the present invention includes a drum unit including a photosensitive drum, and a developing roller that is supported substantially in parallel with the photosensitive drum in a state of being close to the photosensitive drum and can supply a developer to the photosensitive drum. Each of the developing units provided is slidably moved along the rotational axis direction of the photosensitive drum with respect to the apparatus main body so as to be freely inserted and removed separately. The image forming apparatus is provided so as to be switchable between a proximity posture capable of supplying a developer to the photosensitive drum and a separation posture separated from the photosensitive drum, Linked to the operation of inserting the developing unit into the apparatus main body, switching the attitude of the developing roller to the approaching position, and linked to the operation of extracting the developing unit from the apparatus main body. An attitude switching mechanism for switching the developing roller to the separation attitude and an urging means for urging and moving the drum unit in the direction of extraction from the apparatus main body are provided, and the urging force by the urging means is applied to the drum unit. anti a depressible push portion, Ri Oh and movable integrally with the developing unit,
The posture switching mechanism includes a swinging arm that swingably supports the developing unit so that the developing roller switches between the approaching posture and the separation posture, and the developing roller supported by the swinging arm. An urging mechanism that urges the developing unit to switch to the separated position, a shaft member that is supported so as to be movable in an insertion / extraction direction of the developing unit with respect to the apparatus main body, and a front side of the shaft member in the insertion direction with respect to the apparatus main body. An urging member for urging so as to protrude in the direction, and the swinging arm is integrally provided with an arm member that abuts from the direction intersecting the shaft member, and the apparatus main body includes the developing unit. A contact portion that moves the shaft member to the rear side in the insertion direction against an urging force by contact with the contact portion of the shaft member accompanying insertion; The shaft member swings so that the developing roller switches the developing roller to the approaching posture by contact with the arm member accompanying the rearward movement in the insertion direction against the urging force of the shaft member. It is in the point provided with the bent part to be made.

[Action and effect]
Each of the drum unit and the developing unit is slidably moved along the rotational axis of the photosensitive drum with respect to the apparatus main body so that the drum unit and the developing unit can be inserted and removed separately, and the developing unit can be inserted into the apparatus main body. There is a posture switching mechanism that links the developing roller to the close posture and links the developing unit to the separation posture in conjunction with the operation of pulling the developing unit out of the main body of the device. And the separation posture can be switched with good operability, and there is little risk of erroneous operation.
However, since the position of the developing roller is switched to the close position in conjunction with the operation of inserting the developing unit into the apparatus main body, the developing unit is inserted into the apparatus main body with the drum unit mounted on the apparatus main body. When the operation is performed, the posture of the developing roller is switched to the proximity posture before the insertion operation is completed, and the developing roller and the photosensitive drum are moved along with the movement of the developing roller until the subsequent insertion operation is completed. May rub against each other and damage the developing roller and the photosensitive drum.
In addition, since the developing roller is switched to the separated position in conjunction with the operation of extracting the developing unit from the apparatus main body, if the developing unit is extracted from the apparatus main body with the drum unit mounted on the apparatus main body, The developing unit moves in the pull-out direction before the switching to the separated position is completed, and the developing roller and the photosensitive drum rub against each other as the developing roller moves until the switching to the separated position of the developing roller is completed. In this case, the developing roller and the photosensitive drum may be damaged.
Therefore, an urging means for urging and moving the drum unit in the direction of extraction from the apparatus main body is provided, and a pressing portion capable of pressing the drum unit against the urging force of the urging means is provided to be movable integrally with the developing unit. The drum unit can be moved integrally with the developing unit at least immediately before the completion of the inserting operation for inserting the developing unit into the apparatus main body or immediately after the start of the extracting operation for extracting the developing unit from the apparatus main body. The development roller and the photosensitive drum are less likely to rub against each other regardless of whether the development unit is inserted or the development unit is pulled out with the device mounted on the apparatus main body. There is little possibility of hurting.
That is, in a state before the developing unit is inserted into the apparatus main body, the drum unit mounted on the apparatus main body is moved in the pulling direction from the predetermined mounting position by the urging force of the urging means. At least immediately before completion of the insertion operation, the pressing unit that can move integrally with the developing unit presses the drum unit against the urging force of the urging means until the insertion operation of the developing unit is completed. Since the developing unit is moved together with the developing unit, even if the developing roller is switched to the close position before the developing unit insertion operation is completed, the developing roller accompanying the movement of the developing roller until the subsequent inserting operation is completed. And the photosensitive drum can be prevented from rubbing, and there is little risk of scratching the developing roller and the photosensitive drum.
Further, in a state before the developing unit is pulled out from the apparatus main body, the drum unit mounted on the apparatus main body is pressed against the urging force of the urging means by the pressing portion that can move integrally with the developing unit, and is predetermined. The drum unit also moves integrally with the developing unit by the urging force of the urging means along with the integral movement of the pressing portion in the extracting direction at least immediately after the start of the extracting operation of the developing unit. Therefore, the developing roller can be switched to the separated position while moving the drum unit integrally with the developing unit, and even if the developing unit moves in the extraction direction before the switching of the developing roller to the separated position is completed, the developing roller Rubbing between the developing roller and the photosensitive drum along with the movement of the developing roller until the switching to the separated position is completed Can be prevented, there is little fear of damaging the developing roller and the photosensitive drum.

  The second characteristic configuration of the present invention is that the pressing unit is formed by integrally providing a contact member that contacts the lower end of the drum unit in the extraction direction.

[Action and effect]
Since the pressing part is formed by integrally providing the developing unit with an abutting member that abuts the lower end of the drum unit in the pulling direction, the pressing unit can press the drum unit against the urging force of the urging means. The portion can be provided so as to be movable integrally with the developing unit by a simple improvement of the conventional developing unit.

  According to a third characteristic configuration of the present invention, the developing unit includes a second developing roller for supplying a developer to the developing roller, and the swing arm swings around a rotation axis of the second developing roller. It is in the point which is supported freely.

  According to a fourth characteristic configuration of the present invention, the contact portion is provided at a distal end portion of the shaft member in the insertion direction, and the bent portion is provided by bending the shaft member in a U-shape. In the point.

  A fifth characteristic configuration of the present invention is that the urging member is configured by a coil spring loosely fitted to the shaft member.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 6 show a tandem color printer as an example of an electrophotographic image forming apparatus according to the present invention. As shown in FIG. 1, each of toners of four colors of cyan, magenta, yellow, and black is supported. 4 sets of combinations of a drum unit A including the photosensitive drum 1 and a developing unit B including a first developing roller 2 capable of supplying a developer to the photosensitive drum 1 are mounted. The photosensitive drum 1 is provided so that a corresponding color toner image carried on the surface can be transferred to the intermediate transfer belt 3.

  The intermediate transfer belt 3 is an endless belt that is circulated and driven in accordance with an image forming operation. The toner image transferred to the intermediate transfer belt 3 is transferred from the paper feed cassette 4 or the manual feed tray 5 to the paper transport path 6. The image is transferred by the transfer device 7 onto the sheet conveyed through the sheet.

  Each of the drum unit A and the developing unit B is slidably moved along the rotational axis X direction of the photosensitive drum 1 with respect to the apparatus main body C so as to be freely inserted and removed. As shown in FIG. 4, the mounting guide 8 that supports the drum unit A and the developing unit B so as to be slidable separately along the rotation axis X direction and detachably supported, and as shown in FIGS. A fixing mechanism 9 is provided for fixing the unit B to a predetermined mounting position, that is, a position where the developer can be supplied to the photosensitive drum 1 by the first developing roller 2.

  The fixing mechanism 9 includes a fixing pin 10 fixed in the vertical direction on the lower surface of the developing unit B in the insertion direction with respect to the apparatus main body C, and a hook member 11 fixed to the apparatus main body C side. The hook member 11 is formed with a C-shaped ring-shaped engaging portion 12 that allows the fixing pin 10 to be engaged and disengaged from the radial direction.

  Further, there are provided urging means (not shown) such as a compression spring for urging and moving each drum unit A mounted at a predetermined position of the apparatus main body C in the direction of extraction from the apparatus main body C. 2, As shown in FIG. 3, the pressing unit 13 that can press the drum unit A against the urging force of the urging means can be moved integrally with the developing unit B to each corresponding developing unit B. It is provided.

  The pressing portion 13 is configured by integrally forming a developing member B in contact with the lower end portion 14 in the pulling direction of the drum unit A. The developing unit B is arranged at a predetermined mounting position of the apparatus main body C. In the state where the drum unit A is mounted, the drum unit A is also pressed by the contact member 13 against the urging force of the urging means, and the toner image on the photosensitive drum 1 is transferred to the intermediate transfer belt 3 at a predetermined mounting position. The drum unit A is fixed at a position where transfer can be performed, and the drum unit A moves in the extraction direction by a distance corresponding to the urging force by the urging means as the developing unit B is extracted from the apparatus main body C.

  Each of the developing units B is a hybrid type unit that can use a two-component developer. As shown in FIG. 7, the first developing roller 2, the second developing roller 15, the blade 16, and the developing unit A casing 17 filled with an agent, and two agitating members 18 are provided in the casing 17.

  The second developing roller 15 is provided with magnetic poles at a plurality of locations in the circumferential direction so that the developer can be pumped up and peeled off while the blade 16 is on the second developing roller 15. It is provided so that the developer pumped up can be cut off.

  The first developing roller 2 is supported substantially in parallel in a proximity posture in which the developing unit B is close to the photosensitive drum 1 in a state where the developing unit B is mounted at a predetermined mounting position of the apparatus main body C, and is used for image forming operation. Accordingly, the developer is rotated so that the developer pumped up from the second developing roller 15 can be supplied to the photosensitive drum 1.

  A gap roller is attached to both ends of the first developing roller 2 in the direction of the rotation axis, and an urging mechanism (not shown) for urging the first developing roller 2 toward the photosensitive drum 1 is provided. When the developing unit B is mounted at a predetermined mounting position of the apparatus main body C, the gap rollers come into contact with both ends of the photosensitive drum 1 in the rotation axis direction, and the photosensitive drum 1 and the first developing roller 2 are in contact with each other. The interval is configured to be kept substantially constant.

Further, each of the developing units B is linked to an operation of inserting the developing unit B into the apparatus main body C at a predetermined mounting position, and the posture of the first developing roller 2 is changed with respect to the corresponding photosensitive drum 1. The operation is switched to a proximity posture in which the developer can be supplied to the photosensitive drum 1, and the developing unit B mounted at a predetermined mounting position is extracted from the apparatus main body C. A posture switching mechanism 19 is provided that can switch the posture of one developing roller 2 to a separated posture separated from the photosensitive drum 1.

  As shown in FIGS. 8 to 10, the posture switching mechanism 19 is a pair of swings that supports both ends of the first developing roller 2 so as to be swingable about the rotation axis Y of the second developing roller 15. A developing member mounted at a predetermined mounting position of the main body C, and a shaft member 22 supported so as to be movable in the direction of the supporting axis Z across the arm 20, the left and right guide members 21 provided in the casing 17. The shaft member 22 protrudes from the casing 17 of the developing unit B in the direction of the support axis Z in a state where the unit B is urged in the direction of extraction from the apparatus main body C and the developing unit B is extracted from the apparatus main body C. And an arm member 24 provided integrally with each of the swing arms 20 so as to contact the shaft member 22 from above.

  The shaft member 22 has sufficient rigidity so as not to buckle and deform, and a bent portion 25 which is bent in a U-shape toward the arm member 24 in a state where the shaft member 22 is decentered from the support axis Z is formed at both ends. The lower end of the lower side in the insertion direction with respect to the apparatus main body C is bent in a laterally U shape so that the developing unit B is mounted at a predetermined mounting position of the apparatus main body C. A contact portion 26 that contacts a contact portion (not shown) is provided.

  The biasing member 23 is constituted by a coil spring. A shaft support member 22 is inserted into the coil spring 23 and fixed to the casing 17 side. A retaining portion 28 provided on the shaft member 22 is provided. It is attached to the shaft part between.

  The swing arm 20 is urged by an urging means (not shown) such as a spring so that the arm member 24 contacts the shaft member 22 from above.

The operation of the posture switching mechanism 19 will be described.
In the state where only the drum unit A is mounted on the apparatus main body C, as shown in FIG. 2, the drum unit A has moved in the extraction direction by a distance corresponding to the biasing force by the biasing means from a predetermined mounting position.

  Further, as shown in FIG. 9, the developing unit B in a state of being extracted from the apparatus main body C causes the contact portion 26 of the shaft member 22 to be supported from the casing 17 of the developing unit B by the urging force of the coil spring 23. The arm member 24 protrudes in the direction, and is in contact with the shaft portion of the shaft member 22 concentric with the support shaft Z from above.

  Then, in conjunction with the operation of inserting the developing unit B into the apparatus main body C along the mounting guide 8, the contact member 13 contacts the lower end 14 of the drum unit A in the extraction direction as shown in FIG. At the same time, the contact portion 26 of the shaft member 22 contacts the contacted portion on the apparatus main body C side.

  From this state, the drum unit A moves integrally with the developing unit B along the mounting guide 8 in conjunction with the operation of further inserting the developing unit B, and the contact portion 26 is in contact with the apparatus main body C side. As shown in FIG. 10, the shaft member 22 moves along the support axis Z against the urging force of the coil spring 23 and is mounted at a predetermined mounting position of the apparatus main body C. Further, the arm member 24 is pushed up against the bending portion 25 of the shaft member 22 against the urging force of the urging means (not shown), so that the swing arm 20 resists the urging force. Then, it swings in the direction of the arrow 29 in FIG. 8, and the attitude of the first developing roller 2 is switched to a proximity attitude capable of supplying the developer to the photosensitive drum 1.

  In the state in which the posture of the first developing roller 2 is switched to the close posture, the fixing pin 10 is engaged with the engaging portion 12 of the hook member 11 and the developing unit B is attached to the apparatus main body C as shown in FIG. On the other hand, it is mounted at a predetermined mounting position, and the gap roller abuts on the photosensitive drum 1 so that the relative position between the photosensitive drum 1 and the first developing roller 2 is kept constant.

  Then, the drum unit A and the developing unit B are connected to an operation for removing the developing unit B from the apparatus main body C along the mounting guide 8 from the state where the apparatus main body C is mounted at a predetermined mounting position. The pin 10 is disengaged from the engaging portion 12 of the hook member 11 and the developing unit B moves in the withdrawal direction. At the same time, the drum unit A moves along the mounting guide 8 in the withdrawal direction by the biasing force of the biasing means (not shown). Move together with B.

  At this time, the shaft member 22 is moved relative to the casing 17 by the biasing force of the coil spring 23 so that the contact portion 26 protrudes from the casing 17 of the developing unit B in the support axis Z direction as shown in FIG. The arm member 24 is moved down by a biasing force of a biasing means (not shown) so as to come into contact with the shaft portion concentric with the support shaft core Z of the shaft member 22 from above. The swing arm 20 swings in the direction of the arrow 30 in FIG. 8 against the urging force, and the posture of the first developing roller 2 is switched to the separated posture that is separated from the photosensitive drum 1.

  From this state, by further extracting the developing unit B, the developing unit B is extracted from the apparatus main body C while the drum unit A remains in the apparatus main body C.

[Other Embodiments]
1. An image forming apparatus according to the present invention is a movable member capable of reciprocating a pressing portion capable of pressing a drum unit against an urging force of an urging unit along a rotation axis direction of the photosensitive drum, The movable member and the developing unit may be provided so as to be movable integrally with each other.
2. The image forming apparatus according to the present invention may be an electrophotographic image forming apparatus such as a copying machine other than a printer or a fax machine.

Side view showing inside of image forming apparatus Perspective view of main part of developing unit insertion / removal operation seen from the upper side of the unit insertion direction Perspective view of main part of developing unit insertion / removal operation seen from the upper side of the unit insertion direction Perspective view of main part of developing unit insertion / removal operation as seen from the upper side on the lower side in the unit insertion direction Perspective view of main part of developing unit insertion / removal operation as seen from the lower side of the unit insertion direction Perspective view of main part of developing unit insertion / removal operation as seen from the lower side of the unit insertion direction Side view of the main part Perspective view of development unit Perspective view of development unit Perspective view of development unit

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Developing roller 13 Press part (contact member)
14 Lower end
15 Second developing roller 19 Posture switching mechanism
20 Swing arm
22 Shaft member
23 Biasing member (coil spring)
24 Arm member
25 Bending part
26 Abutting section A Drum unit B Development unit X Rotating shaft core
Y Rotational axis of the second developing roller
Z Support axis

Claims (5)

Each of a drum unit including a photosensitive drum and a developing unit including a developing roller that is supported substantially in parallel with the photosensitive drum and capable of supplying a developer to the photosensitive drum, With respect to the apparatus main body, it is slid along the rotational axis direction of the photosensitive drum, and is provided so that it can be inserted and removed separately.
The position of the developing roller can be switched between a proximity position in which the developer roller is close to the photosensitive drum and developer can be supplied to the photosensitive drum and a separation position in which the developer roller is separated from the photosensitive drum. An image forming apparatus provided,
In conjunction with an operation of inserting the developing unit into the apparatus main body, the attitude of the developing roller is switched to the proximity attitude, and in conjunction with an operation of extracting the developing unit from the apparatus main body, the developing roller is A posture switching mechanism for switching to a separated posture;
An urging means for urging and moving the drum unit in the direction of extraction from the apparatus main body; and
The depressible pressing portion against the urging force of the urging means the drum unit, Ri Oh and movable integrally with the developing unit,
The posture switching mechanism is
The developing unit switches the developing roller swingably so as to switch the developing roller between the approaching posture and the separating posture, and switches the developing roller supported by the swinging arm to the separating posture. A biasing mechanism that biases the developing unit, a shaft member that is supported so as to be movable in the insertion / removal direction of the developing unit with respect to the apparatus main body, and a shaft member that protrudes forward in the insertion direction with respect to the apparatus main body. An urging member for energizing,
The swing arm is integrally provided with an arm member that comes into contact with the shaft member from a direction intersecting the shaft member,
The apparatus main body includes a contacted portion that moves the shaft member to the rear side in the insertion direction against a biasing force by contact with the contact portion of the shaft member accompanying insertion of the developing unit,
The shaft member swings the swing arm so that the developing roller switches to the close position by contact with the arm member as the shaft member moves backward in the insertion direction against the urging force of the shaft member. An image forming apparatus including a bent portion to be moved .   The image forming apparatus according to claim 1, wherein a contact member that contacts the lower end portion of the drum unit in the extraction direction of the drum unit is provided integrally with the developing unit.   The developing unit includes a second developing roller for supplying a developer to the developing roller,
  The image forming apparatus according to claim 1, wherein the swing arm is swingably supported around a rotation axis of the second developing roller.   The contact portion is provided at a distal end portion in the insertion direction of the shaft member,
  The image forming apparatus according to claim 1, wherein the bent portion is provided by bending the shaft member into a U-shape.   The image forming apparatus according to claim 1, wherein the urging member is configured by a coil spring that is loosely fitted to the shaft member.

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