JP5139818B2 - Developing device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a developing device for developing a latent image formed on an image carrier and an image forming apparatus provided with the developing device.

  An image forming apparatus such as a copying machine or a printer that forms an image on a sheet by electrophotography develops a latent image formed on an image carrier as a toner image by a developing device, and supplies the toner image at an appropriate timing. The toner image transferred onto the sheet is fixed on the sheet by a fixing device.

By the way, such an image forming apparatus employs a system in which the developing device is attached to and detached from the apparatus main body in the vertical direction, and a developing roller and a stirring member are driven to rotate at one end in the width direction of the developing device. The drive unit is provided, and this drive unit is protected by a cover member.
JP 2003-316138 A JP-A-2005-141024 JP-A-9-297442

  However, in an image forming apparatus that employs a system in which the developing device is attached to and detached from the apparatus main body in a vertical direction, when the driving unit of the developing apparatus mounted in the apparatus main body is driven, the developing device is driven by a driving reaction force. There is a problem that it is easily lifted off from the apparatus main body.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the object of the processing is a developing device capable of performing high-precision positioning in the vertical direction and horizontal direction and retaining in one component, and image formation provided with the same. To provide an apparatus.

In order to achieve the above object, the invention according to claim 1 is a developing device that includes a drive unit and a cover member that protects the drive unit, and is attached to and detached from the apparatus main body in the vertical direction.
Said cover member to form a guide rib which fits into the guide groove of the main body frame together, the upper end portion of said guide rib, said wider than the width of the guide groove of the main frame forming the elastically deformable locking portion In addition, a wide portion that fits into the guide groove of the main body frame is formed at two locations in the vertical direction of the guide rib.

The image forming apparatus according to claim 2, wherein the apparatus is moved up and down the guide rib formed in the cover member of the developing apparatus according to claim 1 Symbol placement along the guide grooves of the developing device is fitted into the guide groove of the main body frame It is characterized by being attached to and detached from the main body.

  According to the present invention, when the developing device is attached to and detached from the apparatus main body in the vertical direction, the developing device is mounted with the guide rib formed on the cover member of the developing device fitted in the guide groove of the main body frame. By moving up and down along the guide groove, the developing device can be smoothly attached and detached while being positioned with high accuracy with respect to the apparatus main body. When the developing device is mounted on the apparatus main body, the engaging portion of the guide rib formed on the cover member of the developing device is locked in the locking groove of the main body frame, so that the developing device generates a driving reaction generated in the driving portion. Even if it receives a force, it does not come out of the main body of the apparatus, and the developing device is reliably prevented from coming off. Therefore, it is possible to accurately position and prevent the developing device in the vertical direction and the horizontal direction with one component of the guide rib.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Image forming apparatus]
FIG. 1 is a cross-sectional view of a color laser printer as an embodiment of an image forming apparatus according to the present invention. The illustrated color laser printer is a tandem type, and a magenta image forming unit is provided at the center of the main body 100. 1M, a cyan image forming unit 1C, a yellow image forming unit 1Y, and a black image forming unit 1K are arranged in tandem at regular intervals.

  Each of the image forming units 1M, 1C, 1Y, and 1K is provided with photosensitive drums 2a, 2b, 2c, and 2d, and charging rollers 3a, 3b, 3c, and 3d are disposed around the photosensitive drums 2a to 2d. 3d, developing devices 4a, 4b, 4c, 4d, transfer rollers 5a, 5b, 5c, 5d and drum cleaning devices 6a, 6b, 6c, 6d are arranged, respectively.

  Here, the photosensitive drums 2a to 2d are drum-shaped photosensitive members, and are rotationally driven at a predetermined process speed in a direction indicated by an arrow (clockwise) by a variable speed stepping motor (not shown). The charging rollers 3a to 3d uniformly charge the surfaces of the photosensitive drums 2a to 2d to a predetermined potential by a charging bias applied from a charging bias power source (not shown).

  Further, the developing devices 4a to 4d contain magenta (M) toner, cyan (C) toner, yellow (Y) toner, and black (K) toner, respectively, and are formed on the photosensitive drums 2a to 2d. In addition, the toner of each color is attached to each electrostatic latent image to visualize each electrostatic latent image as a toner image of each color.

  The transfer rollers 5a to 5d are arranged so as to be able to contact the photosensitive drums 2a to 2d via the intermediate transfer belt 7 in the respective primary transfer portions. Here, the intermediate transfer belt 7 is stretched between the secondary transfer counter roller 8 and the tension roller 9 and is disposed on the upper surface side of each of the photosensitive drums 2a to 2d. The roller 8 is disposed so as to be in contact with the secondary transfer roller 10 via the intermediate transfer belt 7 in the secondary transfer portion. A belt cleaning device 11 is provided in the vicinity of the tension roller 9.

  Incidentally, toner containers 12a, 12b, 12c, and 12d for supplying toner to the developing devices 4a to 4d are arranged in a line above the image forming units 1M, 1C, 1Y, and 1K in the apparatus main body 100. It is installed.

  In addition, a laser scanner unit (LSU) 13 is disposed below the image forming units 1M, 1C, 1Y, and 1K in the apparatus main body 100, and a paper feed cassette 14 is detachably attached to the bottom of the main body 100 below the image forming units. is set up. A plurality of sheets (not shown) are stacked and accommodated in the paper feed cassette 14, and a pickup roller 15 for taking out the paper one by one from the paper feed cassette 14 is taken out in the vicinity of the paper feed cassette 14. A feed roller 16 and a retard roller 17 are provided for feeding the fed paper to the transport path L.

  In addition, the conveyance path L extending in the vertical direction on the side of the apparatus main body 100 includes a conveyance roller pair 18 that conveys the sheet, and the secondary transfer counter roller 8 and the second transfer opposing roller 8 at a predetermined timing after the sheet is temporarily held. A registration roller pair 19 is provided to be supplied to a secondary transfer portion which is a contact portion with the next transfer roller 10. Next to the transport path L, another transport path L ′ used for forming an image on both sides of the sheet is formed, and a plurality of transport roller pairs 20 are appropriately used in the transport path L ′. Are provided at regular intervals.

  By the way, the conveyance path L arranged in the vertical direction on one side in the apparatus main body 100 extends to the paper discharge tray 21 provided on the upper surface of the apparatus main body 100, and the fixing device 22 and the discharge path are in the middle. A paper roller pair 23 is provided.

  Next, an image forming operation by the color laser printer having the above configuration will be described with reference to FIG.

  When an image formation start signal is issued, the photosensitive drums 2a to 2d are driven to rotate at a predetermined process speed in the direction of the arrow in FIG. 1 (clockwise) in each of the image forming units 1M, 1C, 1Y, and 1K. The drums 2a to 2d are uniformly charged by the charging rollers 3a to 3d. The laser scanner unit 13 emits a laser beam modulated by a color image signal for each color, irradiates the surface of each photosensitive drum 2a to 2d with the laser beam, and each color is applied to each photosensitive drum 2a to 2d. An electrostatic latent image corresponding to the color image signal is formed.

  First, magenta toner is attached to the electrostatic latent image formed on the photosensitive drum 2a of the magenta image forming unit 1M by the developing device 4a to which a developing bias having the same polarity as the charged polarity of the photosensitive drum 2a is applied. The electrostatic latent image is visualized as a magenta toner image. This magenta toner image is transferred to the arrow shown in FIG. 1 by the action of the transfer roller 5a to which a primary transfer bias having a polarity opposite to that of the toner is applied at the primary transfer portion (transfer nip portion) between the photosensitive drum 2a and the transfer roller 5a. Primary transfer is performed on the intermediate transfer belt 7 which is rotationally driven in the direction.

  The intermediate transfer belt 7 on which the magenta toner image has been primarily transferred as described above moves to the next cyan image forming unit 1C. In the cyan image forming unit 1C as well, the cyan toner image formed on the photosensitive drum 2b is transferred to the magenta toner image on the intermediate transfer belt 7 in the primary transfer portion in the same manner as described above.

  Similarly, yellow and black toners respectively formed on the photosensitive drums 2c and 2d of the yellow and black image forming units 1Y and 1K on the magenta and cyan toner images superimposed and transferred on the intermediate transfer belt 7, respectively. The images are sequentially superimposed at each primary transfer portion, and a full-color toner image is formed on the intermediate transfer belt 7. The transfer residual toner which is not transferred onto the intermediate transfer belt 7 and remains on the photosensitive drums 2a to 2d is removed by the drum cleaning devices 6a to 6d, and the photosensitive drums 2a to 2d are prepared for the next image formation. It is done.

  Then, the pickup from the paper feed cassette 14 is performed in accordance with the timing at which the front end of the full color toner image on the intermediate transfer belt 7 reaches the secondary transfer portion (transfer nip portion) between the secondary transfer counter roller 8 and the secondary transfer roller 10. The sheet fed to the conveyance path L by the roller 15, the feed roller 16 and the retard roller 17 is conveyed to the secondary transfer unit by the registration roller pair 19. Then, a full-color toner image is collectively transferred from the intermediate transfer belt 7 to the sheet conveyed to the secondary transfer unit by the secondary transfer roller 10 to which a secondary transfer bias having a polarity opposite to that of the toner is applied. .

  Thus, the sheet on which the full-color toner image has been transferred is conveyed to the fixing device 22, and the sheet on which the full-color toner image has been fixed by being heated and pressurized and thermally fixed on the surface of the sheet. Then, the paper is discharged onto the paper discharge tray 21 by the paper discharge roller pair 23 to complete a series of image forming operations. The transfer residual toner that is not transferred onto the sheet and remains on the intermediate transfer belt 7 is removed by the belt cleaning device 11, and the intermediate transfer belt 7 is prepared for the next image formation.

[Developer]
Next, the structure of the developing devices 4a to 4d and the structure for attaching to and detaching from the apparatus main body 100 will be described with reference to FIGS. Since the developing devices 4a to 4d are all the same in structure and detachable structure from the apparatus main body 100, only the yellow developing device 4c will be described below.

  2 is a perspective view of the developing device, FIG. 3 is a perspective view of a main part of the developing device, FIG. 4 is a perspective view of a main body frame to which the developing device is mounted, FIG. 5 is an enlarged detail view of a portion A in FIG. These are the B section enlarged front views of FIG.

As shown in FIG. 2, a developing roller 25 is rotatably supported on a resin casing 24 of the developing device 4c, and the toner container 12c shown in FIG. toner replenishing duct 26 for receiving a supply of toner over are formed. In addition, the other end in the width direction (drive side) of the housing 24 is provided with a drive unit (not shown) including a gear that receives a drive force from a motor (not shown) provided on the apparatus main body 100 side. The drive unit is covered and protected by a resin gear cover 27. When the driving force from the motor on the apparatus main body 100 side is transmitted to the driving unit of the developing device 4c, the driving force is transmitted to the developing roller 25 through a gear, and the developing roller 25 is rotationally driven at a predetermined speed. Is done.

  Thus, the developing device 4c is attached to and detached from the main body frame 101 shown in FIG. 4 in the vertical direction. The gear cover 27 is provided with a guide rib for guiding the developing device 4c when the developing device 4c is attached or detached. 28 is integrally formed.

  On the other hand, as shown in FIGS. 4 to 6, the main body frame 101 is formed with a guide groove 102 for fitting the guide rib 28 formed on the gear cover 27 of the developing device 4c. The main body frame 101 is formed with guide grooves 102 for fitting guide ribs 28 formed in the other three developing devices 4a, 4b, 4d. Here, as shown in FIG. 6, a notch-like locking groove 102 a is formed at an intermediate height position of the guide groove 102 formed in the main body frame 101.

  By the way, wide portions 28 a and 28 b that fit in the guide grooves 102 of the main body frame 101 are formed at the lower end portion and the intermediate height position of the guide rib 28 formed on the gear cover 27 of the developing device 4 c. A locking portion 28c that is wider than the guide groove 102 of the main body frame 101 and can be elastically deformed is formed in an inverted C shape at the upper end portion.

  Thus, in order to mount the developing device 4c to the main body frame 101, the guide rib 28 formed integrally with the gear cover 27 is fitted into the guide groove 102 formed in the main body frame 101, and the developing device 4c is moved downward as it is. And drop. Then, the developing device 4c smoothly moves downward along the guide groove 102 of the main body frame 101. At this time, since the wide portions 28a and 28b of the guide rib 28 are fitted into the guide groove 102, the developing device 4c It moves while being positioned with high accuracy in the horizontal direction with respect to the frame 101. Further, when the developing device 4c moves downward along the guide groove 102 of the main body frame 101, the elastically deformable locking portion 28c formed at the upper end portion of the guide rib 28 is compressed inward. And slides while fitting into the guide groove 102 of the main body frame 101.

  When the developing device 4c is completely attached to the main body frame 101, as shown in FIG. 6, the engaging portion 28c of the guide rib 28 of the developing device 4c expands due to elasticity and returns to the original state. Since the developing device 4c receives the driving reaction force generated in the driving unit, the developing device 4c does not come out of the apparatus main body 101, and the developing device 4c is reliably prevented from coming off. Positioning of the developing device 4c in the vertical direction with respect to the main body frame 101 is performed with high accuracy. Accordingly, the one part of the guide rib 28 formed integrally with the gear cover 27 of the developing device 4c ensures the highly accurate positioning and retaining of the developing device 4c in the vertical direction and the horizontal direction.

  On the other hand, in order to take out the developing device 4c attached to the main body frame 101, the engaging portion 28c of the guide rib 28 of the developing device 4c is pressed inward to be compressed and formed in the engaging portion 28c and the guide groove 102. If the developing device 4c is pulled up as it is in a state where the locked state with the locking groove 102a is released, the developing device 4c is moved upward along the guide groove 102 of the main body frame 101, and the main body frame 101 is moved upward. Can be taken out easily.

  Although the present invention has been described with respect to a mode in which the present invention is applied to a color laser printer and a developing device provided therein, the present invention is similarly applied to a monochrome monochrome image forming apparatus and a developing device provided therein. Of course, the present invention can also be applied to any other image forming apparatus such as a copying machine other than a printer, a facsimile machine, and a developing device provided in the image forming apparatus.

1 is a cross-sectional view of a color laser printer as an embodiment of an image forming apparatus according to the present invention. 1 is a perspective view of a developing device according to the present invention. It is a perspective view of the principal part of the developing device according to the present invention. It is a perspective view of a main body frame to which a developing device according to the present invention is mounted. It is the A section enlarged detail drawing of FIG. It is the B section enlarged front view of FIG.

Explanation of symbols

1M Magenta image forming unit 1C Cyan image forming unit 1Y Yellow image forming unit 1K Black image forming unit 2a to 2d Photosensitive drum 3a to 3d Charge roller 4a to 4d Developing device 5a to 5d Transfer roller 6a to 6d Drum cleaning device 7 Intermediate transfer belt 8 Secondary transfer counter roller 9 Tension roller 10 Secondary transfer roller 11 Belt cleaning device 12a to 12d Toner container 13 Laser scanner unit (LSU)
DESCRIPTION OF SYMBOLS 14 Paper feed cassette 15 Pickup roller 16 Feed roller 17 Retard roller 18 Conveyance roller pair 19 Registration roller pair 20 Conveyance roller pair 21 Paper discharge tray 22 Fixing device 23 Paper discharge roller pair 24 Developing device case 25 Developing roller 26 Toner supply duct 27 Gear cover (cover member)
28 Guide rib 28a, 28b Wide portion of guide rib 28c Locking portion of guide rib 101 Main body frame 102 Guide groove 102a of main body frame Locking groove L, L '

Claims (2)

In a developing device that includes a drive unit and a cover member that protects the drive unit, and is attached to and detached from the apparatus body in the vertical direction.
Said cover member to form a guide rib which fits into the guide groove of the main body frame together, the upper end portion of said guide rib, said wider than the width of the guide groove of the main frame forming the elastically deformable locking portion In addition, a developing device characterized in that wide portions that fit into the guide grooves of the main body frame are formed at two locations in the vertical direction of the guide rib . And characterized in that detachable from the apparatus main body is moved up and down the claims 1 Symbol placement guide rib formed on the cover member of the developing device along the guide grooves of the developing device by fitting the guide groove of the main body frame Image forming apparatus.

Images