JP2007010986A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the space saving of an image forming apparatus by avoiding contact of a developing device with a photoreceptor drum, when the developing device is attached to the image forming apparatus. <P>SOLUTION: The developing device 1 supplies toner to the photoreceptor drum 3 in a printer 10 and is detachably attached to the printer 10, and is equipped with a sleeve roller 15 and a roller contacting/separating mechanism 16. The sleeve roller 15 is arranged proximate to the photoreceptor drum 3 in the printer 10 and can move to approach to or retreat from the photoreceptor drum 3. The roller contacting/separating mechanism 16 can make the sleeve roller 15 operate to approach to or retreat from the photoreceptor drum 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device, and more particularly to a developing device that supplies toner to a photosensitive drum of an image forming apparatus and is detachably attached to the image forming apparatus.

  An image forming apparatus employing an electrophotographic system such as a laser printer includes a photosensitive drum on which a toner image is formed and a developing device for supplying toner to the photosensitive drum. The developing device includes a developing roller disposed close to the photosensitive drum.

  As a conventional developing device, one that can be detachably attached to an image forming apparatus is known. However, as described above, since the developing roller is disposed close to the photosensitive drum, the developing roller may come into contact with the photosensitive drum during the attaching / detaching operation. Therefore, as a conventional developing device, for example, after pressing from the front side in the axial direction toward the predetermined position away from the photosensitive drum in the image forming apparatus, it is moved in the horizontal direction so as to approach the photosensitive drum. There is a type that can be installed.

As related techniques, for example, those shown in Patent Documents 1 and 2 have already been proposed.
JP 2003-167424 A JP 2004-264519 A

  However, the conventional developing device requires a space for sliding to the photosensitive drum side in the image forming apparatus, and thus it is difficult to reduce the size of the image forming apparatus. In such a configuration, it is necessary to provide a guide mechanism or the like in the image forming apparatus for stably sliding a relatively heavy developing device, which complicates the configuration of the image forming apparatus. Further, since the conventional developing device needs to be moved in the image forming apparatus in order to approach or separate from the photosensitive drum, the positioning accuracy of the developing roller with respect to the photosensitive drum is deteriorated.

  SUMMARY OF THE INVENTION An object of the present invention is to avoid contact with a photosensitive drum when a developing device is mounted on an image forming apparatus, and to save space in the image forming apparatus.

  According to a first aspect of the present invention, there is provided a developing device that supplies toner to the photosensitive drum of the image forming apparatus and is detachably attached to the image forming apparatus, and includes a first developing roller, a roller contacting / separating mechanism, It has. The first developing roller can be disposed close to the photosensitive drum in the image forming apparatus, and is movable so as to approach or retract from the photosensitive drum. The roller contact / separation mechanism can be operated to move the first developing roller toward or away from the photosensitive drum.

  When the developing device is mounted on the image forming apparatus, the first developing roller is retracted in advance by operating the roller contact / separation mechanism, and in this state, the image forming apparatus is mounted, for example, by pushing in the axial direction. By operating the rear roller contact / separation mechanism, the first developing roller is disposed close to the photosensitive drum.

  On the other hand, when the developing device is removed from the image forming apparatus, the roller contact / separation mechanism is operated to retract the first developing roller from the photosensitive drum, and then removed by, for example, pulling the image forming apparatus forward in the axial direction. It is.

  Such a developing device can be mounted by moving it in the axial direction with respect to the image forming apparatus because the developing roller can be retracted so as not to come into contact with the photosensitive drum when the image forming apparatus is attached to or detached from the image forming apparatus. Therefore, a space for moving the developing device in the image forming apparatus as in the prior art becomes unnecessary, and the image forming apparatus can be downsized. In addition, this eliminates the need to provide a guide mechanism or the like for supporting the movement of the relatively heavy developing device on the image forming apparatus side, and the configuration of the image forming apparatus can be simplified. Furthermore, according to this developing device, it is possible to directly place the toner image at a predetermined position in the vicinity of the photosensitive drum, so that the positioning accuracy relative to the photosensitive drum is improved.

  The number of developing rollers may be one, or two as in the apparatus of claim 2.

  According to a second aspect of the present invention, the developing device according to the first aspect further includes a second developing roller that is disposed in the vicinity of the first developing roller and supplies toner to the first developing roller.

  Here, in particular, in a developing device that can also cope with a two-component developer (hereinafter also referred to as a hybrid type), the image forming apparatus can be reduced in size. For example, as a developing device employed in a tandem color printer, for example. Is suitable.

  According to a third aspect of the present invention, in the apparatus of the second aspect, the roller contact / separation mechanism includes an arm member, a shaft member, a lever member, and a bearing member. The arm member is rotatably mounted integrally with the second developing roller. The shaft member is movable in the axial direction, and is configured to rotate the arm member when moving in the axial direction. The lever member is operable to move the shaft member in the axial direction. The bearing member receives the rotation shafts of the first and second developing rollers.

  In this apparatus, specifically, the lever member is operated to move the shaft member in the axial direction, and accordingly, the arm member rotates integrally with the second developing roller, and further, the first developing is performed via the bearing member. By operating the roller to rotate, the first developing roller can be brought into contact with and separated from the photosensitive drum.

  According to a fourth aspect of the present invention, in the development apparatus according to any one of the first to third aspects, the image forming apparatus has a printing function for A3 size paper. The photosensitive drum and the first developing roller have axial lengths corresponding to A3 size paper.

  Conventionally, in an image forming apparatus (hereinafter referred to as A4 machine) that prints only paper of A4 size or smaller, the developing apparatus is generally moved in the axial direction and arranged directly in the vicinity of the photosensitive drum. On the other hand, in an image forming apparatus capable of printing A3 size paper (hereinafter referred to as A3 machine), the developing device is once pushed axially into a position away from the photosensitive drum as described above, and then the image forming apparatus. A configuration in which the inside is slid and arranged in the vicinity of the photosensitive drum is generally used, and a configuration that cannot be easily reduced in size has been adopted.

  However, according to the developing device of the fourth aspect, since the first developing roller can be retracted by the roller contact / separation mechanism when the developing device is mounted on the image forming apparatus, the first developing roller is disposed directly at a predetermined position near the photosensitive drum. Can do. Therefore, the image forming apparatus such as the A3 machine can be downsized.

  According to the present invention, when the image forming apparatus is attached to or detached from the image forming apparatus, the developing roller can be retracted so as not to come into contact with the photosensitive drum, so that the image forming apparatus can be mounted by moving in the axial direction. Therefore, a space for moving the developing device in the image forming apparatus as in the prior art becomes unnecessary, and the image forming apparatus can be downsized.

  In addition, this eliminates the need to provide a guide mechanism or the like for supporting the movement of the relatively heavy developing device on the image forming apparatus side, and the configuration of the image forming apparatus can be simplified.

  Furthermore, according to the present invention, it is possible to directly arrange at a predetermined position in the vicinity of the photosensitive drum, so that the positioning accuracy with respect to the photosensitive drum is improved.

<Color printer>
FIG. 1 shows a tandem color printer 10 equipped with a developing device 1 in which an embodiment of the present invention is adopted.

  The printer 10 has a printing function for A3 size paper, and includes four photosensitive drums 3 and developing devices 1 respectively corresponding to toners of four colors of cyan, magenta, yellow, and black, and an intermediate transfer belt 5. I have.

  Each of the photosensitive drums 3 carries a toner image of each color on the surface and transfers the toner image to the intermediate transfer belt 5. The photosensitive drum 3 has an axial length corresponding to A3 size paper.

  The intermediate transfer belt 5 is an endless belt disposed in the printer 10 so as to extend in the horizontal direction, and is circulated and driven in accordance with an image forming operation. The toner image transferred onto the intermediate transfer belt 5 is transferred by the transfer device 8 to the paper transported through the paper transport path 6 from the paper feed cassette 7 or the bypass tray 9.

  Further, the printer 10 is configured so that the developing device 1 can be detachably mounted. Here, the developing device 1 can be disposed at a predetermined position in the vicinity of the photosensitive drum 3 by moving the developing device 1 to the rear side or the front side in the axial direction. It has become.

<Developing device>
FIG. 2 shows the developing device 1.

  Here, only one of the four developing devices 1 will be described, but all are configured similarly except that the color of the toner used is different.

  The developing device 1 is for supplying toner of a predetermined color to the photosensitive drum 3 and is a hybrid type device that can use a two-component developer. The developing device 1 includes a magnetic roller 11 (second developing roller), a blade 13, a sleeve roller 15 (first developing roller), a roller contact / separation mechanism 16, and two stirring members 17 and 19. The casing 21 is provided.

  The magnetic roller 11 has magnetic poles arranged at a plurality of locations in the circumferential direction, and can draw up and peel off the developer while rotating. Similarly to the photosensitive drum 3, the magnetic roller 11 has an axial length corresponding to A3 size paper.

  The blade 13 is a member for trimming the developer pumped up on the magnetic roller 11, and is disposed at two positions facing both axial ends of the magnetic roller 11.

  The sleeve roller 15 is disposed close to the magnetic roller 11 and can be disposed close to the photosensitive drum 3 in the printer 10. The sleeve roller 15 is rotationally driven in accordance with the image forming operation, and can draw up toner from the developer on the magnetic roller 11. The sleeve roller 15 is movable so as to be able to approach or retract from the photosensitive drum 3 by a roller contact / separation mechanism 16.

  The sleeve roller 15 is provided with a gap roller 14 at both ends in the axial direction and an urging mechanism (not shown) for applying an urging force to the photosensitive drum 3 side. As a result, when the developing device 1 is mounted on the printer 10, the gap rollers 14 come into contact with both axial ends of the photosensitive drum 3, and the distance between the photosensitive drum 3 and the sleeve roller 15 is kept constant. Be drunk. Further, like the photosensitive drum 3 and the magnetic roller 11, the sleeve roller 15 has an axial length corresponding to A3 size paper.

  Each of the agitating members 17 and 19 is a member having a shape in which spiral blades are formed on the outer peripheral portion of the shaft, and are arranged in parallel to each other at the bottom portion in the casing 21. The agitating members 17 and 19 are rotationally driven along with the image forming operation, so that the developer can be circulated and conveyed in the casing 21 via a partition wall 22 (described later) of the casing 21.

  The inside of the casing 21 is filled with a developer.

<Roller contact / separation mechanism>
3 to 6 show the roller contact / separation mechanism 16.

  The roller contact / separation mechanism 16 is a mechanism operated to move the sleeve roller 15 toward or away from the photosensitive drum 3, and includes an arm member 23, a shaft member 25, an urging means 26, a lever member 27, and the like. And a bearing member 29.

  The arm member 23 is attached to both ends of the rotating shaft 15a so as to be rotatable integrally with the sleeve roller 15. Each arm member 23 has a support portion 23a that supports the shaft member 25 from below. Each arm member 23 receives an urging force in a direction in which the shaft member 25 abuts from below by an urging member (not shown) such as a spring.

  The shaft member 25 is a rod-like member extending in the axial direction and is movable in the axial direction. The shaft member 25 has an inclined portion 25a that comes into contact with the support portion 23a of the arm member 23 from above, and moves downward in the axial direction (arrow B direction) to push the support portion 23a down in the arrow D direction. The arm member 23 is rotated. Further, the shaft member 25 has a distal end portion 25b attached to the lever member 27 on the front side in the axial direction. The shaft member 25 is made of a general-purpose resin such as polypropylene, so that the vicinity of the distal end portion 25b can be bent in the vertical direction.

  The urging means 26 is a mechanism for urging the shaft member 25 in the axially back side (in the direction of arrow C), and has a function of returning the shaft member 25 moved to the near side by operating the lever member 27 to the back side. Have.

  The lever member 27 is a member for operating the shaft member 25 to move in the axial direction, and is rotatably attached to the casing 21 with the lower end portion 27a as a rotation center. In the vicinity of the lower end portion 27a of the lever member 27, an attachment portion 27b to which the distal end portion 25b of the shaft member 25 is attached is provided. In a state where the lever member 27 is operated in the direction of arrow A and falls to the near side, the shaft member 25 moves to the near side by pulling the tip portion 25b to the attachment portion 27b, and the lever member 27 moves in the direction of the arrow A. In an upright state, the urging force is applied by the urging means 26 to move to the back side.

  The bearing member 29 functions as a link member that receives the rotation shafts 15 a and 11 a of the sleeve roller 15 and the magnetic roller 11 and connects the rollers 15 and 11, and rotates together with the magnetic roller 11. . Therefore, when the magnetic roller 11 rotates together with the arm member 23, the sleeve roller 15 is pulled by the bearing member 29 and rotates so as to approach or retract from the photosensitive drum 3.

<Operation of developing device>
Next, the operation of the developing device 1 will be described.

  Here, a case where the developing device 1 attached to the printer 10 is removed and the removed developing device 1 is attached to the printer 10 again will be described.

  When removing the developing device 1 attached to the printer 10, first, the lever member 27 is moved down to move the shaft member 25 to the near side. Then, the arm member 23 is pushed downward by the inclined portion 25a of the shaft member 25, whereby the magnetic roller 11 rotates and the sleeve roller 15 is separated from the photosensitive drum 3 via the bearing member 29 in the direction of arrow E. To turn. At this time, the urging force of the sleeve roller 15 toward the photosensitive drum 3 by the urging mechanism is released.

  When the developing device 1 is pulled out in the axial direction with the sleeve roller 15 retracted, the sleeve roller 15 can be detached from the printer 10 without contacting the photosensitive drum 3.

  On the other hand, when the developing device 1 is attached to the printer 10, the lever member 27 is tilted forward and the sleeve roller 15 is retracted, and the sleeve roller 15 is pushed back in the axial direction to be set at a predetermined position in the printer 10. . When the lever member 27 is raised in this state, the shaft member 25 receives the urging force of the urging means 26 and moves to the back side, and the arm member 23 is integrated with the magnetic roller 11 along with the arrow D along with this. It rotates in the opposite direction. Then, the sleeve roller 15 rotates in the direction opposite to the arrow E direction via the bearing member 29 and is disposed in the vicinity of the photosensitive drum 3. At this time, the gap roller 14 contacts the photosensitive drum 3 on the sleeve roller 15, and the distance between the photosensitive drum 3 and the sleeve roller 15 is kept constant.

  According to the developing device 1 described above, the sleeve roller 15 can be moved toward or away from the photosensitive drum 3 in the printer 10, so that the sleeve 10 can be moved away from the printer 10 in the axial direction or away from the printer 10. Can be installed.

  Therefore, it is not necessary to provide a space in the printer for moving the developing device in the horizontal direction after it is once pushed into a position away from the photosensitive drum as in the prior art, and the printer can be miniaturized.

  Further, it is not necessary to provide a guide mechanism or the like on the printer side for supporting the movement of the relatively heavy developing device, so that the printer can have a simple configuration. Further, since the developing device can be directly arranged at a predetermined position of the printer, the positioning accuracy with respect to the photosensitive drum is stabilized.

<Other embodiments>
(A) The roller contact / separation mechanism is not limited to the one described in the above embodiment, and may be configured to make the sleeve roller approach or retreat with respect to the photosensitive drum using other members and mechanisms. It ’s fine.

  (B) The developing device of the present invention is not limited to the hybrid developing device, and can be applied to a developing device having only one developing roller.

  (C) The developing device of the present invention is not limited to a tandem color printer, but can be applied to a printer dedicated to monochrome printing or a one-drum color printer.

  (D) The image forming apparatus to which the developing device of the present invention is attached is not limited to a printer, but adopts an electrophotographic system such as a multifunction machine having other functions such as a copying function and a facsimile function. It may be.

1 is a longitudinal sectional view showing a printer equipped with a developing device employing an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing the developing device. FIG. 3 is a perspective view showing the developing device. FIG. 2 is a perspective view of an essential part showing an enlarged principal part of the developing device. FIG. 3 is a perspective view showing the developing device while being partially broken and partially disassembled. FIG. 3 is a perspective view showing the developing device with a part broken away.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing apparatus 3 Photosensitive drum 10 Printer (image forming apparatus)
11 Magnetic roller (second developing roller)
13 Sleeve roller (first developing roller)
16 Roller contact / separation mechanism 23 Arm member 25 Shaft member 27 Lever member 29 Bearing member

Claims (4)

A developing device that supplies toner to a photosensitive drum of an image forming apparatus and is detachably attached to the image forming apparatus,
A first developing roller that can be disposed in the image forming apparatus in the vicinity of the photosensitive drum, and is movable to be close to or retractable from the photosensitive drum;
A roller contact / separation mechanism operable to move the first developing roller toward or away from the photosensitive drum;
A developing device comprising:   The developing device according to claim 1, further comprising a second developing roller that is disposed in proximity to the first developing roller and supplies toner to the first developing roller. The roller contacting / separating mechanism is
An arm member rotatably mounted integrally with the second developing roller;
A shaft member movable in the axial direction and configured to rotate the arm member when moving in the axial direction;
A lever member operable to move the shaft member in the axial direction;
A bearing member for receiving the rotation shafts of the first and second developing rollers;
The developing device according to claim 2, comprising: The image forming apparatus has a printing function for A3 size paper,
The photosensitive drum and the first developing roller have an axial length corresponding to A3 size paper.
The developing device according to claim 1.

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