JP2006171411A - Drum driving unit and tandem type image forming apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drum driving unit capable of improving the quality of an image obtained in an image forming apparatus by decreasing vibration. <P>SOLUTION: The drum driving unit 3 has a housing 10, a drum driving motor 13 provided to the housing 10 and a gear mechanism 20. The gear mechanism 20 is provided to the housing 10, and includes 1st and 2nd input gears 25 and 30 for receiving driving force given from one housing 10 arranged adjacently, 1st and 2nd transmission gears 26 and 29 for transmitting the driving force received from the 1st and the 2nd input gears 25 and 30 to another housing 10 arranged adjacently, and a developing device driving shaft 33 and a cleaning unit driving shaft 32 for outputting the driving force received from the 1st and the 2nd input gears 25 and 30 as the driving force for a developing device 46 and a cleaning unit 47. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tandem type image forming apparatus including a plurality of photosensitive drums, such as a full-color image forming apparatus, and a drum driving unit that drives the photosensitive drums.

  In a full-color image forming apparatus, yellow, magenta, cyan, and black toner images are transferred to a sheet to form a full-color image. Each color toner image is obtained by transferring a predetermined color toner onto an electrostatic latent image formed on the peripheral surface of a dedicated photosensitive drum. The photosensitive drums for the respective colors are rotationally driven by a drum driving unit having a corresponding dedicated motor.

FIG. 6 is a perspective view showing the structure of a drum drive unit provided in a conventional full-color image forming apparatus.
The drive unit 51 includes a flat base 52 and four motors 53, 54, 55, 56 mounted on the base 52 in a row. These motors 53, 54, 55, 56 have the same structure and each have a drive shaft 60.

The drive unit 51 is attached to, for example, a main body frame (for example, a side plate) of the image forming apparatus, and each drive shaft 60 is coupled to a photosensitive drum (not shown). As a result, the driving force of the motors 53, 54, 55, and 56 is transmitted to the corresponding photosensitive drum, and each photosensitive drum rotates.
JP 2002-40738 A Japanese Patent Laid-Open No. 9-230661

However, when the four motors 53, 54, 55, and 56 are mounted on the common base 52 and configured as a unit as a whole, the individual motors 53, 54, 55, and 56 The vibration is easily transmitted to the main body of the image forming apparatus, and there is a problem that the formed image is deteriorated.
In addition, the photosensitive drum of the image forming apparatus has a positioning portion, and is positioned with respect to the main body frame by the positioning portion. The drive unit 51 is, for example, a pin at two places on the left and right sides. It is positioned and fixed to the main body frame. For this reason, the positional accuracy of the drive shaft 60 with respect to the photosensitive drum is accumulated by the positional accuracy of the photosensitive drum (drum unit) with respect to the main body frame (such as dimensional tolerance of the positioning member) and the positional accuracy of the driving unit 51 with respect to the main body frame. It will be.

In addition, since the positions of the four motors 53, 54, 55, 56 with respect to the image forming apparatus main body are determined at the same time, the positional accuracy of each of the motors 53, 54, 55, 56 in the drive unit 51 is also driven with respect to the photosensitive drum. Accumulated in the positional accuracy of the shaft 60.
For this reason, if the positional accuracy is poor, driving unevenness and noise of the photosensitive drum by the driving unit 51 may occur.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of reducing the vibration and improving the quality of an obtained image, and a drum driving unit used therefor.
Another object of the present invention is to provide an image forming apparatus in which the positional accuracy of the photosensitive drum with respect to the drum driving unit is improved.

  In order to achieve the above object, the invention according to claim 1 is a housing, a drum driving motor provided in the housing, and a housing provided adjacent to the housing. An input gear for receiving a driving force applied from the transmission gear, a transmission gear for transmitting the driving force received from the input gear to another adjacent housing, and a drive received from the input gear A drum drive unit comprising: a gear mechanism including output means for outputting a force as a drive force for a predetermined device separately from the drive force of the drum drive motor.

  According to the present invention, one motor is provided for one housing. That is, each motor is not directly attached to a common base. Therefore, by fixing such a drum drive unit to the main body frame of the image forming apparatus, vibration transmitted from the motor of each drum drive unit to the image forming apparatus main body can be reduced, and the quality of the obtained image can be reduced. Can be improved.

  In the image forming apparatus, the plurality of drum drive units are engaged with a transmission gear provided in the housing of the first drum drive unit and an input gear provided in the housing of the second drum drive unit. Adjacent arrangements can be used. As a result, the driving force can be transmitted from the transmission gear of the first drum driving unit (housing) to the input gear of the second drum driving unit (housing) disposed adjacent thereto. The force can be output as a predetermined driving force for the apparatus via output means provided in each housing.

  The input gear of the first drum driving unit may be configured to receive a driving force from a common driving source arranged outside the casings of the first and second drum driving units. In this case, the driving force from the common driving source can be output from the output means provided in each housing, and the predetermined device can be driven. That is, a predetermined device associated with each of the plurality of drum drive units can be driven by one drive source.

Similarly, three or more drum drive units are arranged adjacent to each other, and the driving force from a common drive source is output from the output means provided in the case of each drum drive unit, corresponding to each drum drive unit. An attached predetermined device can be driven.
According to a second aspect of the present invention, two gear mechanisms may be provided. In this case, one of the output mechanisms may output a driving force for the cleaning roller, and the other may be the other. The output unit may output a driving force for the developing roller.

That is, the developing unit provided in the cleaning roller provided in the cleaning unit that cleans the peripheral surface of the photosensitive drum or the developing unit that supplies the toner of each color to the peripheral surface of the photosensitive drum by the output unit of each drum driving unit. The roller can be driven.
The housing may be formed of resin as described in claim 3. The housing formed of resin absorbs more vibration generated by the drum drive motor than when the housing is formed of metal, for example, and greatly reduces the vibration transmitted to the image forming apparatus main body. Can be reduced.

According to a fourth aspect of the present invention, there is provided a tandem type image forming apparatus comprising a drum driving source in which four drum driving units according to any one of the first to third aspects are arranged in parallel.
According to the present invention, the same effects as those of the first to third aspects of the invention can be achieved.
According to a fifth aspect of the present invention, there is provided a drum drive source in which four drum drive units according to the second aspect are arranged in parallel, and the one output means is coupled to the cleaning unit via a universal joint. In the tandem type image forming apparatus, the other output means is coupled to the developing roller via a universal joint.

According to the present invention, one and the other output means of the drum drive unit are respectively coupled to the cleaning roller and the developing roller via the universal joint. As a result, the driving of the photosensitive drum is less affected by disturbance due to the driving of the cleaning roller and the driving of the developing roller, and uneven rotation of the photosensitive drum can be suppressed.
According to a sixth aspect of the present invention, the drum driving motor includes a drum driving shaft that rotationally drives the photosensitive drum, and the drum driving unit further includes a cylindrical member through which the drum driving shaft is inserted. The drum driving unit is positioned with respect to the main body frame of the image forming apparatus by the cylindrical member, and the photosensitive drum is positioned with respect to the drum driving shaft. The tandem type image forming apparatus according to claim 4 or 5.

According to this invention, the drum drive unit is positioned with respect to the main body frame by the cylindrical member into which the drum drive shaft is inserted. Thereby, the positional accuracy of the drum driving shaft with respect to the main body frame is increased.
Further, the photosensitive drum is directly positioned with respect to the drum driving shaft of the drum driving unit, not the image forming apparatus main body. Therefore, in this image forming apparatus, the positional accuracy of the photosensitive drum with respect to the drum driving unit is improved.

  As a result, the photosensitive drum is aligned with high accuracy with respect to each drum driving unit individually with respect to the drum driving shaft disposed inside the cylindrical member. For this reason, driving unevenness can be reduced, and the photosensitive drum can be driven stably and with reduced noise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a perspective view showing the structure of an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus 1 can form full-color images by transferring toner images of yellow, magenta, cyan, and black to paper. When an image is formed, an electrostatic latent image is formed on the circumferential surface of four photosensitive drums (not shown) that are uniformly charged in advance, and yellow, magenta, and magenta are respectively formed on the circumferential surface of the photosensitive drum. By supplying toner of each color of cyan and black, the electrostatic latent image is developed into a toner image of each color. These toner images are sequentially transferred onto a sheet to form a full color image.

  The image forming apparatus 1 includes a main body side plate 2A as a main body frame, a high voltage substrate 2B attached substantially in parallel to the main body side plate 2A, and a drum drive source 9 for driving four photosensitive drums. Yes. The drum drive source 9 includes four drum drive units 3, 4, 5, and 6 that are attached to the main body side plate 2A in the horizontal direction. That is, the image forming apparatus 1 is a tandem type image forming apparatus including four drum driving units 3, 4, 5, and 6 arranged in parallel. Each drum drive unit 3, 4, 5, 6 includes a housing 10 and is configured as an independent unit.

  Each drum drive unit 3, 4, 5, 6 has a drum drive motor 13, 14, 15, 16. The photosensitive drums for forming the toner images of the respective colors are arranged on the opposite side of the main body side plate 2A from the drum drive units 3, 4, 5, and 6. These photosensitive drums are rotationally driven around their axes by drum drive motors 13, 14, 15, 16 of drum drive units 3, 4, 5, 6 respectively.

  Further, a developing motor 7 is provided adjacent to the drum drive unit 3 on the side opposite to the drum drive unit 4 with respect to the drum drive unit 3. Further, a cleaning motor 8 is provided at a position opposite to the drum drive unit 5 with respect to the drum drive unit 6 and lower than the drum drive units 3, 4, 5, 6. The development motor 7 and the cleaning motor 8 are respectively attached to the main body side plate 2A via dedicated attachment plates 7P and 8P.

The drum drive units 3, 4, and 5 have the same structure. Hereinafter, the structure of the drum drive unit 3 will be described as a representative.
2A and 2B are perspective views showing the structure of the drum drive unit 3, and FIGS. 2C and 2D are perspective views showing the structure of the housing 10. FIG. 2E is a perspective view of the drum driving motor 13 provided in the drum driving unit 3.

The housing 10 has a rectangular and flat mounting base portion 11 and a side wall portion 12 which is provided upright from the periphery of the mounting base portion 11 and includes four plate-like portions. The housing 10 is made of resin, and the mounting base portion 11 and the side wall portion 12 are integrally formed.
The drum driving motor 13 has a drum driving shaft 17 that is coupled to the photosensitive drum and rotationally drives the photosensitive drum. The drum drive shaft 17 is inserted through a boss (cylindrical member) 18 that is substantially coaxial with the drum drive shaft 17. The drum drive motor 13 is attached to one surface of the attachment base portion 11, and the drum drive shaft 17 and the boss 18 protrude to the other surface side of the attachment base portion 11.

  Two bearings 17B1 and 17B2 and a driving force transmission member 17T formed in a ring shape by a frame body are sequentially fitted on the drum drive shaft 17 from the motor main body side to the tip side (see FIG. 2E). . The drum drive shaft 17 is rotatably fitted to the boss 18 via bearings 17B1 and 17B2. The driving force transmission member 17T has a ridge 17P protruding toward the tip side of the drum driving shaft 17.

  The drum drive unit 3 further includes a gear mechanism 20. The gear mechanism 20 includes a first gear train 21 and a second gear train 22. The first gear train 21 and the second gear train 22 are provided on the other surface side (drum drive shaft 17 side) of the attachment base portion 11, and the first gear train 21 is attached to the attachment base from the second gear train 22. It is arranged on the side close to the part 11.

The first gear train 21 includes a first input gear 25, a first transmission gear 26 meshed with the first input gear 25, and a drive gear 37 meshed with the first input gear 25. A developing device drive shaft 33 for driving the developing device is attached to the drive gear 37 along the central axis. The developing device drive shaft 33 rotates integrally with the drive gear 37.
The second gear train 22 includes an intermediate transmission gear 27, an intermediate transmission gear 28 that meshes with the intermediate transmission gear 27, and a second transmission gear 29 that meshes with the intermediate transmission gear 28. The second transmission gear 29 is rotatably attached around the developing device drive shaft 33. The second gear train 22 further includes a second input gear 30 that meshes with the intermediate transmission gear 27, and a drive gear 31 that meshes with the second input gear 30.

Accordingly, the rotational driving force input to the second input gear 30 is transmitted to the second transmission gear 29 via the intermediate transmission gears 27 and 28.
A cleaning unit drive shaft 32 that drives the cleaning unit is attached to the drive gear 31 along the central axis thereof. The cleaning unit drive shaft 32 rotates integrally with the drive gear 31.

The developing device drive shaft 33 and the cleaning unit drive shaft 32 protrude in the same direction as the drum drive shaft 17 with respect to the mounting base portion 11 of the housing 10. Further, screw guides 35 and 36 for inserting screws for fastening the drum drive unit 3 to the main body side plate 2A protrude from the pair of diagonal portions of the mounting base portion 11.
The first transmission gear 26 and the intermediate transmission gear 27 are rotatably mounted around the common support shaft 34 independently of each other. The first transmission gear 26 and the intermediate transmission gear 27 have substantially the same radius, and their peripheral portions slightly protrude from the same plate-like portion of the side wall portion 12. From the plate-like portion, the peripheral edge portion of the second input gear 30 also slightly protrudes.

As for the 1st input gear 25 and the 2nd transmission gear 29, those peripheral parts are the plate-shaped parts of the side wall part 12 (The plate-shaped part which opposes the plate-shaped part from which the 1st transmission gear 26 and the intermediate transmission gear 27 protrude) ) Protruding slightly.
FIG. 3 is a plan view showing the vicinity of the main body side plate 2 </ b> A of the image forming apparatus 1. In FIG. 3, the casing 10, the boss 18 and the screw guides 35 and 36 are not shown.

  Each drum drive unit 3, 4, 5, 6 is fixed to the main body side plate 2 </ b> A by screws inserted through screw guides 35, 36. Thus, a predetermined distance is maintained between the casing 10 of each drum drive unit 3, 4, 5, 6 and the main body side plate 2A. In this state, the first gear train 21 and the second gear train 22 are between the mounting base portion 11 of the housing 10 and the main body side plate 2A, and the drum drive shaft 17, the cleaning unit drive shaft 32, and the developing device drive. The tip of the shaft 33 protrudes on the opposite side to the drum drive units 3, 4, 5, 6 with respect to the main body side plate 2A.

  A photosensitive drum 45 is coupled to the tip of the drum drive shaft 17, and an electrostatic latent image formed on the peripheral surface of the photosensitive drum 45 is developed into a toner image on the side of the photosensitive drum 45. And a cleaning unit 47 for cleaning the peripheral surface of the photosensitive drum 45 are disposed (in FIG. 3, the photosensitive drum 45, the developing device 46, and the drum driving units 4, 5, and 6). The cleaning unit 47 is not shown).

The developing device 46 and the cleaning unit 47 extend along the longitudinal direction of the photosensitive drum 45 and are disposed so as to face the peripheral surface of the photosensitive drum 45.
The developing device 46 is provided with a developing roller 48 for supplying each color toner to the peripheral surface of the photosensitive drum 45. A developing roller 48 is coupled to the tip of the developing device driving shaft 33 via a universal joint 33U. When the developing device driving shaft 33 rotates, the developing roller 48 is rotated integrally.

The cleaning unit 47 includes a cleaning roller 49, and the cleaning roller 49 is coupled to the tip of the cleaning unit drive shaft 32 via a universal joint 32U. When the cleaning unit drive shaft 32 rotates, the cleaning roller 49 rotates. It is rotated together.
The cleaning unit drive shaft 32 and the developing device drive shaft 33 are coupled to the cleaning roller 49 and the developing roller 48 via the universal joints 32U and 33U, respectively, so that the photosensitive drum 45 is driven by the cleaning roller 49. In addition, it is less affected by disturbance caused by driving of the developing roller 48, and the rotation unevenness of the photosensitive drum 45 is suppressed.

A rotational driving force of the developing motor 7 is input to the first input gear 25 of the drum driving unit 3 via a plurality of gears 38.
The first transmission gear 26 of the drum drive unit 3 and the first input gear 25 of the drum drive unit 4 are engaged with each other, and the second input gear 30 of the drum drive unit 3 and the second transmission gear 29 of the drum drive unit 4 are engaged with each other. I'm engaged.

The first transmission gear 26 of the drum drive unit 4 and the first input gear 25 of the drum drive unit 5 are engaged with each other, and the second input gear 30 of the drum drive unit 4 and the second transmission gear 29 of the drum drive unit 5 are engaged. I'm engaged.
The drum drive unit 6 has substantially the same structure as the drum drive units 3, 4, and 5, but the first input gear 25 is not provided. For this reason, the rotational driving force is not input to the drum driving unit 6 from the first transmission gear 26 of the adjacent drum driving unit 5. On the other hand, the rotational transmission force from the cleaning motor 8 is transmitted to the intermediate transmission gear 27 of the drum drive unit 6 via a plurality of gears 40. The drum drive unit 6 is provided with an intermediate transmission gear 39 that transmits the rotational driving force of the intermediate transmission gear 28 to the drive gear 37.

  Referring to FIGS. 2A, 2B and 3, the rotational driving force received by the first input gear 25 of the drum driving unit 3 from the developing motor 7 via the plurality of gears 38 is the first transmission gear 26. Is transmitted to the first input gear 25 provided in the casing 10 of the drum drive unit 4 disposed adjacent thereto. This rotational driving force is further transmitted by the first transmission gear 26 of the drum driving unit 4 to the first input gear 25 provided in the casing 10 of the drum driving unit 5 disposed adjacent thereto.

  In each drum drive unit 3, 4, 5, the rotational driving force transmitted to the first input gear 25 is transmitted to the developing device drive shaft 33 via the drive gear 37. By this rotational driving force, the developing device 46 (developing roller 48) coupled to the developing device drive shaft 33 is driven. That is, the developing device 46 for the photosensitive drum 45 driven by the drum driving units 3, 4, and 5 is simultaneously driven by the developing motor 7.

  On the other hand, the rotational drive force received by the intermediate transmission gear 27 of the drum drive unit 6 from the cleaning motor 8 via the plurality of gears 40 is adjacent to the drum drive unit 5 disposed adjacent to the second transmission gear 29. Is transmitted to the second input gear 30 provided in the casing 10. This rotational driving force is further transmitted by the second transmission gear 29 of the drum driving unit 5 to the second input gear 30 provided in the casing 10 of the drum driving unit 4 disposed adjacent thereto. This rotational driving force is further transmitted by the second transmission gear 29 of the drum driving unit 4 to the second input gear 30 provided in the casing 10 of the drum driving unit 3 disposed adjacent thereto.

In each drum drive unit 6, 5, 4, 3, the rotational drive force transmitted to the intermediate transmission gear 27 is transmitted to the cleaning unit drive shaft 32 via the second input gear 30 and the drive gear 31. This rotational driving force drives the cleaning unit 47 (cleaning roller 49) coupled to the cleaning unit drive shaft 32.
Further, in the drum drive unit 6, the rotational driving force transmitted to the intermediate transmission gear 27 is transmitted to the developing device drive shaft 33 via the intermediate transmission gear 39 and the drive gear 37. By this rotational driving force, the developing device 46 (developing roller 48) coupled to the developing device drive shaft 33 is driven.

  That is, the cleaning unit 47 for the photosensitive drum 45 driven by the drum driving units 6, 5, 4, and 3 is simultaneously driven by the cleaning motor 8 and the photosensitive member driven by the drum driving unit 6. Because of the drum 45, the developing device 46 is driven simultaneously. As a result, among the developing devices 46 corresponding to the drum drive units 3, 4, 5 and 6, the developing device 46 corresponding to the drum drive unit 6 can be driven independently.

In each of these drum drive units 3, 4, 5, 6, one drum drive motor 13, 14, 15, 16 is provided for one housing 10. That is, the drum driving motors 13, 14, 15, and 16 are not directly attached to a common base. Therefore, vibration transmitted from the drum drive motors 13, 14, 15, 16 of the drum drive units 3, 4, 5, 6 to the main body of the image forming apparatus 1 can be reduced, and the quality of the obtained image can be improved. Further, since the housing 10 is made of resin, vibrations generated by the drum driving motors 13, 14, 15, 16 can be compared with, for example, the case 10 made of metal. Thus, more vibration can be absorbed and the vibration transmitted to the main body of the image forming apparatus 1 can be greatly reduced.

  4 is an enlarged plan view showing the main body side plate 2A and the drum drive unit 3 of the image forming apparatus 1. As shown in FIG. A hole 2H having an inner diameter substantially equal to the outer diameter of the boss 18 is formed in the main body side plate 2A, and the tip of the boss 18 is attached to the main body side plate 2A with the drum drive unit 3 attached to the main body side plate 2A by screws. Is fitted in the hole 2H. Thereby, the drum drive unit 3 is positioned with respect to the main body side plate 2A, and the positional accuracy of the drum drive shaft 17 with respect to the main body side plate 2A is increased.

  At the tip of the cleaning unit drive shaft 32, a joint member 32A that forms a universal joint 32U together with the end of the cleaning roller 49 is provided. The joint member 32A includes a disk member 32D that is coaxial with the cleaning unit drive shaft 32, and an engagement protrusion 32P that is provided on the disk member 32D and engages with an end of the cleaning roller 49.

Similarly, a joint member 33 </ b> A that forms a universal joint 33 </ b> U together with the end of the developing roller 48 is provided at the tip of the developing device drive shaft 33. The joint member 33A includes a disk member 33D that is coaxial with the developing device drive shaft 33, and an engaging protrusion 33P that is provided on the disk member 33D and engages with an end of the developing roller 48.
FIG. 5A is a perspective view showing the structure of the photosensitive drum 45 and the cleaning unit 47.

The photosensitive drum 45 and the cleaning unit 47 are configured as one unit (drum unit) 50, and the developing device 46 (see FIG. 3) is attached to the drum unit 50.
The drum unit 50 has a longitudinal shape along the photosensitive drum 45, and two cylindrical members 41 </ b> B and 45 </ b> B coaxial with the photosensitive drum 45 protrude at one end coupled to the drum driving unit 3. . The cylindrical member 45B is disposed inside the cylindrical member 41B. Two slits 45S along the axial direction are formed in the cylindrical member 45B.

FIG. 5B is a cross-sectional view of the drum unit 50 and the drum drive unit 3 and shows a cross section along the axial direction of the photosensitive drum 45 and the drum drive shaft 17.
The drum unit 50 includes a unit frame 61 that houses the photosensitive drum 45 and the cleaning roller 49 (not shown in FIG. 5B). The unit frame 61 has a longitudinal shape along the longitudinal direction of the photosensitive drum 45, but FIG. 5B shows only a wall portion orthogonal to the longitudinal direction.

  The cylindrical member 41 </ b> B is provided on a wall portion of one end (right side in FIG. 5B) engaged with the drum drive unit 3 in the unit frame 61, and is formed integrally with the unit frame 61. The cylindrical member 41B protrudes outside the unit frame 61 (on the drum drive unit 3 side). The unit frame 61 is formed with a hole having an inner wall continuous with the inner wall of the cylindrical member 41B.

A bearing member 65 </ b> A is provided at one end of the photosensitive drum 45. The photosensitive drum 45 has a cylindrical shape, and the bearing member 65A is fitted in the photosensitive drum 45 at one end thereof, and rotates integrally with the photosensitive drum 45.
The cylindrical member 45B is formed integrally with the bearing member 65A and protrudes toward the one end side of the photosensitive drum 45. The bearing member 65A is formed with a circular center hole 45A which is coaxial with the photosensitive drum 45 and has a continuous wall surface including the inner wall of the cylindrical member 45B. Two engaging pieces (not shown) extending in the axial direction of the photosensitive drum 45 are provided around the cylindrical member 45B.

The outer diameter of the cylindrical member 45B is slightly smaller than the inner diameter of the cylindrical member 41B. The cylindrical member 45B is inserted into the cylindrical member 41B, and is attached in a state where it is not completely positioned with respect to the unit frame 61.
A bearing member 65B is provided at the other end (left side in FIG. 5B) of the photosensitive drum 45. The bearing member 65B is fitted in the photosensitive drum 45. The bearing member 65B has a circular center hole 45C that is coaxial with the photosensitive drum 45. One end of a positioning pin 62 having an outer diameter substantially the same as the diameter of the center hole 45C is inserted into the center hole 45C. The other end of the positioning pin 62 is positioned on the unit frame body 61 and fastened with a screw or the like. It is fixed by means. The bearing member 65B (photosensitive drum 45) is rotatably supported by the positioning pin 62.

  In the drum drive unit 3, bearings 17B1 and 17B2 (the bearings 17B1 (see FIG. 2E) are not shown in FIG. 5B) are rotatably fitted to the drum drive shaft 17. The outer diameters of the bearings 17B1 and 17B2 are substantially equal to the inner diameter of the corresponding portion of the boss 18, and the bearings 17B1 and 17B2 are supported in contact with the boss 18. The bearings 17B1 and 17B2 are fixed at positions in the longitudinal direction of the drum drive shaft 17.

On the other hand, the driving force transmission member 17T rotates integrally with the drum driving shaft 17, but can move freely in the longitudinal direction of the drum driving shaft 17. A spring 17C is interposed between the bearing 17B2 and the driving force transmission member 17T so that the driving force transmission member 17T can be urged away from the bearing 17B2.
The outer diameter of the cylindrical member 41 </ b> B of the unit frame 61 is substantially equal to the inner diameter of the boss 18 of the drive unit 3. When the drum unit 50 is combined with the drum driving unit 3 and mounted on the image forming apparatus main body, the cylindrical member 41B is fitted inside the boss 18 protruding from the main body side plate 2A and positioned with respect to the drum driving unit 3. Is done.

  At this time, the drum drive shaft 17 of the drum drive unit 3 is inserted into the center hole 45A, and the drum drive shaft 17 and the cylindrical member 45B (photosensitive drum 45) are positioned coaxially. Further, the protrusion 17P of the driving force transmitting member 17T fitted to the drum driving shaft 17 is fitted into the slit 45S (see FIG. 5A) of the cylindrical member 41A, and the rotational driving force from the drum driving shaft 17 is passed through the cylindrical member 41A. Then, it is transmitted to the photosensitive drum 45.

  With the above configuration, the photosensitive drum 45 is not positioned with respect to the main body side plate 2 </ b> A, but is positioned coaxially with respect to the drum driving shaft 17 of the drum driving unit 3. For this reason, in this image forming apparatus 1, the positional accuracy of the photosensitive drum 45 with respect to the drum drive unit 3 is improved. Thereby, the photosensitive drum 45 can be driven stably and with reduced noise.

The drum drive units 4, 5, and 6 are similarly attached to the main body side plate 2A, and the corresponding drum unit 50 (photosensitive drum 45) is aligned with the drum drive shaft 17 of the drum drive units 4, 5, and 6. Is done. As a result, the positional accuracy can be increased, and each photosensitive drum 45 can be driven stably and with reduced noise.
FIG. 5C is a cross-sectional view perpendicular to the axes of the photosensitive drum 45, the cleaning roller 49, and the developing roller 48.

  The cleaning roller 49 is urged toward the central axis of the photosensitive drum 45 by springs 63 at both ends of the shaft. Thereby, the peripheral surface of the cleaning roller 49 and the peripheral surface of the photosensitive drum 45 are in contact with each other. The cleaning roller 49 is held by the unit frame 61 (see FIGS. 5A and 5B) in a state where it is regulated so as not to move more than a certain distance in the central axis direction of the photosensitive drum 45.

  Disc-shaped space rollers (not shown) having a diameter larger than that of the developing roller 48 are attached to both ends of the developing roller 48 coaxially with the photosensitive drum 45. An urging mechanism is provided on the shaft of the developing roller 48. When the developing device 46 is attached to the drum unit 50, the developing roller 48 is urged in the direction of the central axis of the photosensitive drum 45, and the space The outer peripheral surface of the roller and the peripheral surface of the photosensitive drum 45 are in contact with each other.

With such a configuration, the positional accuracy of the cleaning roller 49 and the developing roller 48 with respect to the drum driving unit 3 is also improved, and the photosensitive drum 45 can be driven stably and with reduced noise.
The above is an example of the embodiment of the present invention, and the present invention is not limited to this. For example, the drum drive unit 6 may have the first input gear 25 and the intermediate transmission gear 39 as in the drum drive units 3, 4, and 5. In this case, when the first transmission gear 26 of the drum driving unit 5 and the first input gear 25 of the drum driving unit 6 are meshed, the rotational driving force from the developing motor 7 is applied to all the drum driving units 3. , 4, 5 and 6 to the developing device drive shaft 33. For this reason, only the developing device drive shaft 33 of the drum drive unit 6 cannot be driven alone, but it is not necessary to make the drum drive units 3, 4, 5 and the drum drive unit 6 separately. In addition, the cost can be reduced.

  In addition, various design changes can be made within the scope of the matters described in the claims.

1 is a perspective view showing a structure of an image forming apparatus according to an embodiment of the present invention. It is a perspective view which shows the structure of a drum drive unit. It is a perspective view which shows the structure of a drum drive unit. It is a perspective view which shows the structure of a housing | casing. It is a perspective view which shows the structure of a housing | casing. It is a perspective view of a drum driving motor. 2 is a plan view showing the vicinity of a main body side plate of the image forming apparatus. FIG. FIG. 2 is an enlarged plan view showing a main body side plate and a drum drive unit of the image forming apparatus. It is a perspective view which shows the structure of a photoconductor drum and a cleaning unit. It is sectional drawing of a drum unit and a drum drive unit. 2 is a cross-sectional view perpendicular to the axes of a photosensitive drum, a cleaning roller and a developing roller. FIG. It is a perspective view which shows the structure of the drum drive unit with which the conventional full color image forming apparatus was equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3, 4, 5, 6 Drum drive unit 9 Drum drive source 10 Case 13, 14, 15, 16 Drum drive motor 17 Drum drive shaft 18 Boss (cylindrical member)
DESCRIPTION OF SYMBOLS 20 Gear mechanism 25 1st input gear 26 1st transmission gear 27 2nd input gear 29 2nd transmission gear 32 Cleaning unit drive shaft 32U, 33U Universal joint 33 Developing device drive shaft 45 Photoconductor drum 46 Developing device 47 Cleaning unit 48 Developing Roller 49 Cleaning roller

Claims (6)

A housing,
A drum driving motor provided in the housing;
An input gear for receiving a driving force provided from one casing disposed adjacent to the casing, and to another casing disposed adjacent to the driving force received from the input gear. And a gear mechanism including an output means for outputting a driving force received from the input gear as a driving force for a predetermined device separately from the driving force of the drum driving motor. And a drum driving unit. Two gear mechanisms are provided,
On the one hand, the output means outputs a driving force for the cleaning roller,
2. The drum drive unit according to claim 1, wherein the output means outputs a driving force for the developing roller.   3. The drum driving unit according to claim 1, wherein the casing is made of resin.   4. A tandem type image forming apparatus comprising a drum drive source in which four drum drive units according to claim 1 are arranged in parallel. The drum drive unit according to claim 2 comprises four drum drive sources arranged in parallel,
The one output means is coupled to the cleaning roller via a universal joint;
The tandem-type image forming apparatus, wherein the other output means is coupled to the developing roller via a universal joint. The drum driving motor includes a drum driving shaft that rotationally drives the photosensitive drum,
The drum driving unit further includes a cylindrical member through which the drum driving shaft is inserted;
The drum drive unit is positioned with respect to the main body frame of the image forming apparatus by the cylindrical member,
6. The tandem image forming apparatus according to claim 4, wherein the photosensitive drum is positioned with respect to the drum driving shaft.

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