JP2002072766A - Structure of drum driving joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize the structure of a drum driving joint which can smoothly transmit a rotating force even if the joint center of a driving shaft and the center of a photosensitive drum shift from each other are deviated. SOLUTION: An eccentric joint 23 which includes a driving-side joint 33, a relaying plate 34, and a drum-side joint 35 and is so set that the moving direction of the driving-side joint 33 and relaying plate 34 in a plane perpendicular to the driving shaft 21 is almost perpendicular to the moving direction of the repeating plate 34 and drum-side joint 35 in a plane perpendicular to the driving shaft 21 is interposed between a photoreceptor drum 7 and the driving shaft 21; and communication holes are formed in the driving-side joint 33, repeating plate 34, and drum-side joint 35 respectively and the driving shaft 21 is inserted into the through holes and has a pressure end 36 atop to restrict the unidirectional movement of the eccentric joint 23 along the shaft. Further, a coil spring 32 is fitted to the driving shaft 21 to press the eccentric joint 23 against the press end side 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for a drum drive joint for rotating a sheet conveying roller for guiding a sheet to an image forming section.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a facsimile, a printer, or the like, a fed paper passes through a photosensitive drum on which a toner image of a document image is formed, so that a toner image is transferred to the paper. Is done. The photosensitive drum is driven to rotate by a drive shaft connected to a drive motor. More specifically, the joint attached to the drive shaft is inserted into the hole of the drum flange of the photosensitive drum by the pressing force of the spring, whereby the rotational driving force is transmitted to the photosensitive drum.

[0003]

By the way, during assembly, if the center of the joint of the drive shaft and the center of the photosensitive drum are shifted,
The joint and the drum flange are worn and loosely fitted, and finally the joint overcomes the pressing force of the spring and comes off the flange, so that the driving force cannot be transmitted. In particular, in an image forming apparatus that handles wide and long sheets such as A0 size and A1 size, when the photosensitive drum is assembled,
Due to the space required for installation and removal of the photoconductor drum, the rotation axis of the photoconductor drum is perpendicular to the rotation axis of the photoconductor drum. Cheap.

SUMMARY OF THE INVENTION It is an object of the present invention to realize a structure of a drum drive coupling which can transmit a rotational force smoothly even if the center of the coupling of the drive shaft is deviated from the center of the photosensitive drum.

[0005]

The structure of the drum drive coupling according to the present invention comprises a drive-side coupling and a relay plate between a photoreceptor drum and a drive shaft for transmitting a rotational driving force to the photoreceptor drum. , The movement direction of the drive-side joint and the relay plate in the plane perpendicular to the drive shaft, and the movement direction of the relay plate and the drum-side joint in the plane perpendicular to the drive shaft, By forming a communication hole in the drive-side joint, the relay plate, and the drum-side joint, interposing the eccentric joint set at a right angle, passing the drive shaft through the communication hole, and using the tip as the holding end, the eccentric joint is formed. In addition to restricting movement in one direction along the axis, an urging member is attached to the drive shaft, and the eccentric joint is pressed against the holding end by an urging member.

According to the above configuration, since the eccentric joint is pressed against the holding end by the biasing member, when the drive-side joint and the relay plate move in a plane perpendicular to the drive shaft, When moving against the urging force of the urging member and the relay plate and the drum side joint move in a plane perpendicular to the drive shaft,
It moves against the urging force of the possible urging member. When removing the photosensitive drum, the eccentric joint may be moved in a direction opposite to the pressing end against the urging force of the urging member.

[0007] The relay plate is preferably made of resin. This is because if the resin is used, the sliding resistance is small. A convex rib for reducing a sliding load is provided on a surface of the relay plate that slides with a drive-side joint, and a convex rib for reducing a sliding load is provided on a surface of the relay plate that slides with a drum-side joint. Is more preferable.

[0008]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a front sectional view showing the entire copying machine. The copier 1 is provided from a paper storage unit 2 for storing roll paper or cut paper, a transport mechanism 3 for feeding paper to the image forming unit 5, an optical system for reading a document, and an optical system. An image forming unit 5 for forming an image based on light and transferring the image to a sheet, a fixing device 6 for fixing the image transferred to the sheet, a document table 11 and the like are provided.

The original table 11 is movable, and is connected to the original transport plate 12 when it is moved in the direction of arrow A. The transport mechanism 3 includes a pair of registration rollers 23 a and 23 b for aligning the leading ends of the sheets to be copied, and a pair of pre-transfer rollers 24 a and
24b and the like. The image forming unit 5 includes a photosensitive drum 7, a charger 8 for charging the photosensitive drum 7, an exposing unit 4 for forming an electrostatic latent image, and an electrostatic latent image formed on the photosensitive drum 7. A developing device 9 for developing a toner image and a cleaner 10 for cleaning residual toner are included.

The fixing device 6 includes a fixing roller 64 for heating the sheet, a pressure roller 65 that is in pressure contact with the fixing roller 64,
Oil application roller 6 that supplies oil to fixing roller 64
6. It has a discharge roller 67 for discharging the sheet after fixing. FIG. 2 shows a drive shaft 21 rotated and driven by a drive motor (not shown) via a belt and a pulley 22, a joint 23 mounted on the drive shaft 21, and a drum flange 24 having a hole for inserting the joint 23. 3 is a perspective view showing a photosensitive drum 7 connected to a drum flange 24. FIG.

FIG. 3 shows the joint 2 mounted on the drive shaft 21.
3 is an exploded perspective view of FIG. The joint 23 includes a spring holding plate 31, a pressing spring 32, a drive-side joint 33, a relay plate 34, a drum flange-side joint 35, and a joint holding pin 36 joined to the drive shaft 21. The drive shaft 21 is basically a cylindrical rod (having a diameter of D
1), but as shown in FIG.
The portion 21a ahead of the mounting portion 1 is shaped like an oval cross section by cutting off both side surfaces. Let D2 be the thickness of the cut-off portion.

Further, the tip 21b has a cylindrical shape with a diameter D2, and a female screw 21c is formed at the tip thereof. The drive-side joint 33 is made of metal and has a circular plate 33a.
A hollow boss 33c is formed through the boss 33c. Radiation from the boss 33c is formed on the surface of the disc 33a in contact with the relay plate 34.
A ridge 33b that is convex in the direction is formed. Boss part 3
The shape of the inner surface of 3c is an oval cross section, and the larger inside diameter is almost D1, and the small inside diameter is almost D2. The tip 21a of the drive shaft 21 passes through the boss 33c without play. The diameter of the boss 33c itself is D3.

The relay plate 34 is a disk made of a resin such as polyimide or Teflon (registered trademark).
4a is provided. The inner diameter of the circular hole 34a is D4, and there is a relationship of D4> D3. The difference between D4 and D3 is
This is the vertical movable distance of a plane perpendicular to the drive shaft 21 of the relay plate 34. On the surface of the relay plate 34 that is in contact with the drive-side joint 33, a groove 34b is formed in which the convex ridge 33b can be fitted. Furthermore, this groove 34b
Parallel to the surface 33a of the drive-side joint 33 that contacts the relay plate
And a convex rib 34c that slides in contact with is formed.

The joint 3 of the relay plate 34 on the drum flange side
A groove 34d is formed on the surface in contact with 5 in a direction substantially perpendicular to the groove 34b. Further, in parallel with the groove 34d, a convex rib 34e is formed which slides in contact with the surface of the drum flange side joint 35 which is in contact with the relay plate.
The drum flange side joint 35 is provided with a hole 35a at the center thereof, through which the drive shaft passes.

FIG. 5 is a perspective view of a surface 35c of the drum flange side joint 35 in contact with the relay plate, and FIG. 6 is a side sectional view. A convex ridge 3 that fits into a groove 34d formed in the relay plate 34 is provided on a surface 35c that is in contact with the relay plate.
5b are formed in two directions of radiation. Drive shaft through hole 3
The inner diameter of 5a is D5 (D1 <D5 <D3) on the surface 35c that is in contact with the relay board, but narrows inside the joint and widens again to form a step 35d (see FIG. 6). At this step 35d, the joint holding pin 36 is stopped. An engagement piece 35e that engages with an engagement hole in the end face of the drum flange 24 when inserted into the end face of the drum flange 24 is formed at the tip of the joint 35 on the drum flange side.

The interval D6 between the convex ridges is substantially equal to D3. In addition, there is a relationship of D6> D7,
The difference D6-D7 is the movable distance in the left-right direction of a plane perpendicular to the drive shaft 21 of the joint 35. Furthermore, D
8> D9, and the difference D8-D9 is the distance that the joint 35 can move in the vertical direction on a plane perpendicular to the drive shaft 21. FIG. 7 is a perspective view of the drum flange 24 attached to the end of the photosensitive drum 7. A receiving portion 24a for receiving the tip of the drum flange side joint 35 is formed on the end face of the drum flange 24, and an engaging hole 34b for engaging with the engaging piece 35e is formed therein.

With the structure as described above, a driving spring 33 is passed through the tip of the driving shaft 21 to which the spring holding plate 31 is joined, and the driving joint 33, the relay plate 34, and the drum flange joint 35 are inserted. With the joint holding pin 36
Then, the drum drive coupling shown in FIG. 3 is assembled. In the drum drive coupling shown in FIG. 3, if there is no pressing spring 32, the drive side coupling 33 and the relay plate 34
The drum flange side joint 35 can freely move between the spring holding plate 31 and the joint holding pin 36, but is actually pressed by the joint holding pin 36 because of the pressing spring 32. You.

This drum drive coupling drum flange 2
4, the photosensitive drum 7 can be driven to rotate from the drive shaft 21. If the center axes of the drive shaft 21 and the drum flange 24 of the photosensitive drum 7 do not coincide, the drive side joint 33 and the relay plate 34 move in one direction, overcoming the pressing force of the joint holding pin 36. Since the relay plate 34 and the drum flange side joint 35 relatively move in a direction perpendicular to this, the relay plate 34 and the drum flange side joint 35 can function as an eccentric (Oldham) joint.

As described above, the relay plate 34 is made of resin, and the surface 33 of the drive-side joint 33 which is in contact with the relay plate is provided.
a, and a convex rib 34e that slides in contact with the surface of the drum flange side joint 35 that comes into contact with the relay plate is formed. The movement between the relay plate 33 and the relay plate 34 can be performed smoothly, and the movement between the relay plate 34 and the drum flange side joint 35 can be performed smoothly. Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an entire copying machine.

FIG. 2 is a perspective view showing a use state of a joint 23 mounted on the drive shaft 21, a drum flange 24 having a hole into which the joint 23 is inserted, and a photosensitive drum 7 connected to the drum flange 24.

3 is a perspective view showing a joint 23 mounted on a drive shaft 21. FIG.

FIG. 4 is an exploded perspective view of a joint 23 mounted on the drive shaft 21.

FIG. 5 is a perspective view of a surface 35c of the drum flange side joint 35 that contacts the relay plate.

FIG. 6 is a side sectional view of a drum flange side joint 35;

FIG. 7 is a perspective view of a drum flange 24 attached to an end of the photosensitive drum 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copier 5 Image forming part 21 Drive shaft 22 Pulley 23 Joint 24 Drum flange 31 Spring holding plate 32 Pressing spring 33 Drive side joint 34 Relay plate 34c Rib 34e Rib 35 Drum flange side joint 36 Joint holding pin

Claims (4)

[Claims] 1. A drive side coupling between a photoreceptor drum for transferring a toner image onto a sheet and a drive shaft for transmitting a rotational driving force to the photoreceptor drum, comprising a drive side joint, a relay plate, and a drum side joint. An eccentric joint is set in which the direction of movement of the joint and the relay plate in the plane perpendicular to the drive shaft and the direction of movement of the relay plate and the drum-side joint in the plane perpendicular to the drive shaft are substantially perpendicular. By forming communication holes in the drive-side joint, relay plate, and drum-side joint respectively, passing the drive shaft through the communication hole, and using the tip as the holding end, movement in one direction along the axis of the eccentric joint And a biasing member is attached to the drive shaft, and the eccentric joint is pressed against the holding end side by the biasing member. 2. The structure according to claim 1, wherein said relay plate is made of resin. 3. The structure according to claim 2, wherein a convex rib for reducing a sliding load is provided on a surface of said relay plate which slides with the drive-side joint. 4. The structure of a drum drive coupling according to claim 2, wherein a convex rib for reducing a sliding load is provided on a surface of said relay plate which slides with the drum side coupling.