Drive transmission device and image forming apparatus including the same

Patent metadata

Field	Value
Publication number	US-9891580-B2
Application number	US-201614989650-A
Country	US
Kind code	B2
Filing date	Jan 6, 2016
Priority date	Jan 9, 2015
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

An elastic force of an elastic member 11 required for rotating a driven rotational body 8 b is decreased. A first rotational body 8 d and a second rotational body 9 a arranged downstream of a driven rotational body 8 b in a drive train that transmits a driving force from a driving rotational body 7 to a driven member 4 are included. The first rotational body 8 d rotates in synchronization with the driven rotational body 8 b . The second rotational body 9 a is rotated by the first rotational body 8 d and rotates the driven member 4 . The first rotational body 8 d rotates without rotating the second rotational body 9 a when the driven rotational body 8 b rotates by an elastic force of an elastic member 11.

First claim

The invention claimed is:

1. A drive transmission device comprising:
a driving rotational body;
a driven rotational body that rotates by engaging with the driving rotational body;
a driven member that is driven by the rotation of the driven rotational body;
an elastic member that rotates the driven rotational body by an elastic force when the driven rotational body does not engage with the driving rotational body; and
a first rotational body and a second rotational body arranged downstream of the driven rotational body in a drive train that transmits a driving force from the driving rotational body to the driven member, the first rotational body being configured to rotate in synchronization with the driven rotational body, the second rotational body being configured to be rotated by the first rotational body and drive the driven member,
wherein the first rotational body and the second rotational body are gears that mesh with each other,
wherein the first rotational body rotates without rotating the second rotational body when the driven rotational body rotates by the elastic force of the elastic member,
wherein an arcuate surface coaxial with a rotation center of the first rotational body is provided in a portion of the first rotational body that faces the second rotational body in a phase in which the first rotational body does not rotate the second rotational body, and an arcuate surface extending along the arcuate surface of the first rotational body is provided in a portion of the second rotational body that faces the first rotational body in the phase in which the first rotational body does not rotate the second rotational body,
wherein, in a state where the arcuate surface of the first rotational body and the arcuate surface of the second rotational body are in contact with each other, the first rotational body rotates without rotating the second rotational body when the driven rotational body rotates by the elastic force of the elastic member, and
wherein the elastic member is a torsion spring of which center being coaxial with a rotation axis of the second rotational body.

2. The drive transmission device according to claim 1 , wherein the first rotational body rotates the second rotational body when the driven rotational body engages with the driving rotational body and rotates.

3. The drive transmission device according to claim 1 , wherein the number of teeth of the first rotational body is larger than the number of teeth of the second rotational body by one tooth.

4. The drive transmission device according to claim 1 , wherein the driving rotational body and the driven rotational body are gears that mesh and engage with each other, and the driven rotational body has a portion that does not have a gear portion and does not mesh with the driving rotational body.

5. The drive transmission device according to claim 1 , wherein the driven rotational body is rotated to a position, at which the engagement between the driven rotational body and the driving rotational body is completely released, by the elastic force of the elastic member.

6. The drive transmission device according to claim 1 , wherein the driven rotational body is rotated from a position, at which the engagement between the driven rotational body and the driving rotational body is completely released, in a direction in which the driven rotational body engages with the driving rotational body, by the elastic force of the elastic member.

7. The drive transmission device according to claim 1 , wherein the driven rotational body has a pressed surface that is pressed by the elastic force of the elastic member, and the driven rotational body rotates as a result that the pressed surface is pressed.

8. The drive transmission device according to claim 1 , wherein the driven rotational body has a pressing surface that presses the elastic member, and the pressing surface presses and deforms the elastic member against the elastic force of the elastic member when the driven rotational body engages with the driving rotational body and rotates.

9. The drive transmission device according to claim 1 , wherein the driven rotational body holds an engagement member that can engage with the driving rotational body, and the engagement member can move between a position, at which the engagement member engages with the driving rotational body, and a position, at which the engagement member does not engage with the driving rotational body, by moving relative to the driven rotational body.

10. The drive transmission device according to claim 9 , wherein the engagement member is urged in a direction from the position, at which the engagement member does not engage with the driving rotational body, to the position, at which the engagement member engages with the driving rotational body.

11. The drive transmission device according to claim 1 ,
wherein the driven member includes a cam portion, and
wherein the drive transmission device comprises urging means for urging the cam portion, the cam portion being configured to rotate against an urging force of the urging means.

12. An image forming apparatus comprising:
the drive transmission device according to claims 1 ;
toner-image forming means for forming a toner image on an image bearing body; and
a transfer roller that transfers the toner image formed on the image bearing body onto a transferred member,

wherein the transfer roller is moved away from the image bearing body by rotating the driven member of the drive transmission device.

13. The drive transmission device according to claim 1 , further comprising: another driven rotational body that rotates coaxially with the driven rotational body by engaging with the driving rotational body; and another elastic member provided between the driven rotational body and the other driven rotational body, wherein the driven rotational body is rotated to a position, at which the engagement between the driven rotational body and the driving rotational body is completely released, by the elastic force of the elastic member against an urging force of the other elastic member.

14. The drive transmission device according to claim 1 , wherein the driven member is a moving member that moves in a reciprocating manner between a first position and a second position, the moving member being configured to move to the first position as a result that the moving member contacts the second rotational body and is pressed against an urging force of urging means, the moving member being configured to move to the second position by the urging force of the urging means.

15. An image forming apparatus comprising:
the drive transmission device according to claim 14 ; a developing member that causes a toner to adhere to an image bearing body; and a drive source that rotates the developing member,
wherein a driving force from the drive source is not transmitted to the developing member when the driven member of the drive transmission device is at the first position, and the driving force from the drive source is transmitted to the developing member and the developing member rotates when the driven member of the drive transmission device is at the second position.

Assignees

• Canon Kk

Inventors

• Chino Hideto
• Ochi Junichi

Classifications

• F16H1/20

  involving more than two intermeshing members · CPC title

• G03G21/1647 Primary

  Mechanical connection means · CPC title

• G03G2215/0177

  Rotating set of developing units · CPC title