Drive transmitter and image forming apparatus incorporating the drive transmitter

1. A drive transmitter comprising:

a first coupler mounted on an axial end of a first rotary shaft and provided with extensions, which extend in an axial direction thereof and are arranged at intervals in a rotation direction thereof;

a second coupler mounted on an axial end of a second rotary shaft and provided with contact parts to which respective extensions contact between the first rotary shaft and the second rotary shaft upon drive transmission; and

reinforcing ribs provided to the respective extensions and reinforcing the respective extensions, wherein a rotation center part of the reinforcing ribs projects closer to the second coupler than the extensions, wherein a top surface of each of the extensions and a top surface of each of the reinforcing ribs on a side of the second coupler tilt at a substantially equal angle to each other, relative to a top surface in a longitudinal direction of each of the extensions.

2. The drive transmitter according to claim 1 , wherein the reinforcing ribs of the respective extensions are coupled with each other.

3. The drive transmitter according to claim 1 , wherein the reinforcing ribs extend from the respective extensions toward a center of rotation of the first coupler and are coupled at the center of rotation.

4. The drive transmitter according to claim 1 , wherein each coupling portion provided between the reinforcing ribs and the respective extensions is formed in an R shape.

5. The drive transmitter according to claim 4 , wherein an end of the R shape on a side of the extensions is located closer to a center of rotation of the first coupler than a drive coupling circle that links respective centers of the extensions.

6. The drive transmitter according to claim 1 ,

wherein at least one of the first coupler and the second coupler is mounted on a corresponding one of the first rotary shaft and the second rotary shaft swingably by a given angle with respect to the axial direction thereof,

wherein each surface of the extensions contacting the contact parts upon drive transmission and the contact parts are formed in an arc shape.

7. The drive transmitter according to claim 1 , wherein the first coupler includes at least three extensions.

8. The drive transmitter according to claim 1 ,

wherein the second coupler includes extension insertion holes to which the extensions are inserted and a rib insertion hole to which the reinforcing ribs are inserted,

wherein the reinforcing ribs extend from the respective extensions toward a center of rotation of the first coupler and are coupled at the center of rotation.

9. The drive transmitter according to claim 8 ,

wherein the first coupler is mounted on the first rotary shaft swingably by a given angle with respect to the axial direction thereof,

wherein, when the first coupler inclines in the axial direction under the own weight thereof, a leading end of the rotation center part of the reinforcing ribs is located closer to the second coupler than the leading ends of the extensions.

10. The drive transmitter according to claim 1 , wherein the second coupler is formed of resin and the first coupler is formed of either one of metal and resin having a flexural modulus greater than the second coupler.

11. The drive transmitter according to claim 1 ,

wherein at least one of the first coupler and the second coupler is mounted on a corresponding one of the first rotary shaft and the second rotary shaft swingably by a given angle with respect to the axial direction thereof,

wherein the first coupler includes projections at a leading end of each of the extensions, each of the projections projecting in the rotation direction and contacting a corresponding one of the contact parts of the second coupler.

12. The drive transmitter according to claim 1 ,

wherein the reinforcing ribs extend from the respective extensions toward a center of rotation of the first coupler and are coupled at the center of rotation,

wherein, when viewing the first coupler in the axial direction, based on a line segment connecting a center of each of the extensions and the center of rotation of the first coupler, a thickness of each of the reinforcing ribs on an upstream side in the rotation direction of the reinforcing ribs upon drive transmission is greater than a thickness of the reinforcing ribs on a downstream side in the rotation direction thereof.

13. The drive transmitter according to claim 1 ,

wherein at least one of the first coupler and the second coupler is mounted on a corresponding one of the first rotary shaft and the second rotary shaft swingably by a given angle with respect to the axial direction thereof,

wherein the second coupler includes extension insertion holes to which the extensions are inserted,

wherein a length of each of the extension insertion holes in the rotation direction is shorter than a length of the extension insertion holes in a normal direction.

14. The drive transmitter according to claim 1 ,

wherein at least one of the first coupler and the second coupler is mounted on a corresponding one of the first rotary shaft and the second rotary shaft swingably by a given angle with respect to the axial direction thereof,

wherein the reinforcing ribs extend from the respective extensions toward a center of rotation of the first coupler and are coupled at the center of rotation,

wherein the second coupler includes a rib insertion hole to which the reinforcing ribs are inserted toward the center of rotation, and extension insertion holes to which the extensions are inserted and linking to the rib insertion hole,

wherein (D 1 −D 4 )/2>X SIN θ is satisfied, where “θ” represents a maximum inclination angle taken by either one of the first coupler and the second coupler inclinable with respect to the axial direction when the first coupler and the second coupler are coupled, “X” represents a length of each of the extensions in the axial direction, “D 1 ” represents a diameter of a drive coupling circle that links respective centers of the extensions, and “D 4 ” represents an inner diameter of the rib insertion hole.

15. The drive transmitter according to claim 1 ,

wherein one coupler of the first coupler and the second coupler is a moving coupler that is mounted on the first rotary shaft swingably by a given angle and movably in a given area with respect to the axial direction,

wherein the moving coupler includes

a biasing member being mounted on the first rotary shaft and configured to apply a biasing force and to bias the moving coupler toward the other coupler of the first couple and the second coupler when the moving coupler is moved in a direction separating from the other coupler; and

a bearing member configured to contact the biasing member and being mounted on the first rotary shaft and to prevent the biasing member from directly contacting the moving coupler before the moving coupler starts to move from the other coupler of the first coupler and the second coupler.

16. The drive transmitter according to claim 15 ,

wherein the moving coupler further includes

a mounting hole part to which the first rotary shaft is inserted, the mounting hole part having an inner diameter greater than an outer diameter of the first rotary shaft; and

an intermediate member arranged between the bearing member and the biasing member and movable in the axial direction.

17. The drive transmitter according to claim 1 ,

wherein one coupler of the first coupler and the second coupler is a moving coupler that is mounted on the first rotary shaft swingably by a given angle and movably in a given area with respect to the axial direction,

wherein the moving coupler includes

a mounting hole part having an inner diameter greater than an outer diameter of the first rotary shaft to which the first rotary shaft is inserted;

a biasing member to bias the moving coupler toward the other coupler of the first coupler and the second coupler when the moving coupler is moved in a direction separating from the other coupler; and

an intermediate member arranged between the moving coupler and the biasing member and movable in the axial direction.

18. An image forming apparatus comprising:

an image forming device to form an image on a recording medium; and

the drive transmitter according to claim 1 to transmit a drive force to the image forming device.

19. The drive transmitter according to claim 1 , wherein both the extensions of the first coupler and the rotation center part of the reinforcing ribs have a cylindrical shape, and wherein an axial length of the rotation center part in a direction of the first rotary shaft is greater than an axial length of the extensions in the direction of the first rotary shaft.

20. The drive transmitter according to claim 1 , wherein each of the extensions and the rotation center are coupled by the reinforcing ribs.