Belt device including support portions and an adjuster to adjust positions of the support portions

1. A belt device comprising:

a belt unit including:

a plurality of rotators; and

a belt looped around the plurality of rotators;

a frame including a plurality of support portions to support the belt unit;

a biasing member to bias the belt unit supported by the frame in a predetermined direction; and

an adjuster to adjust a position of at least one of the plurality of support portions.

2. The belt device according to claim 1 , wherein the plurality of support portions includes a main reference and a sub-reference, and

wherein the adjuster is disposed at the sub-reference and on a front side of the belt device.

3. An image forming apparatus comprising:

an image bearer to bear a toner image; and

the belt device according to claim 1 ,

wherein the belt is a transfer belt pressed against the image bearer, and

wherein the toner image is transferred from the image bearer onto the belt in a transfer nip between the image bearer and the belt.

4. The image forming apparatus according to claim 3 , wherein the image bearer is an intermediate transferor, and

wherein the belt is a secondary transfer belt.

5. The image forming apparatus according to claim 3 , further comprising a sensor to detect the toner image; and

a bracket on which the sensor is mounted,

wherein a position of the bracket is determined with respect to the belt unit.

6. The image forming apparatus according to claim 5 , wherein the sensor is opposed to one of the plurality of rotators via the belt, and

wherein the position of the bracket is determined with respect to a shaft of the one of the plurality of rotators.

7. The image forming apparatus according to claim 5 , further comprising a bracket support to support the bracket,

wherein the adjuster is to adjust a position of the at least one of the plurality of support portions and a position of the bracket support.

8. The image forming apparatus according to claim 7 , wherein the bracket support is a support shaft, and

wherein the bracket is pivotable on the support shaft.

9. The image forming apparatus according to claim 8 , wherein the support shaft is attached to the frame supporting the belt unit.

10. The image forming apparatus according to claim 8 , further comprising a frame shaft disposed at a position of the image forming apparatus different from the support shaft being the bracket support,

wherein the frame is pivotable on the frame shaft.

11. The image forming apparatus according to claim 7 ,

wherein the bracket support is a support shaft, and

wherein the frame and the bracket are pivotable on the support shaft.

12. A belt device comprising:

a belt unit including:

a plurality of rotators; and

a belt looped around the plurality of rotators;

a frame including a plurality of support portions to support the belt unit;

a biasing member to bias the belt unit supported by the frame in a predetermined direction; and

an adjuster to adjust a twist of the belt unit relative to the frame.

13. An image forming apparatus comprising:

an image bearer to bear a toner image; and

the belt device according to claim 12 ,

wherein the belt is a transfer belt pressed against the image bearer, and the toner image is transferred from the image bearer onto the belt in a transfer nip between the image bearer and the belt.

14. The image forming apparatus according to claim 13 , further comprising a sensor to detect the toner image; and

a bracket on which the sensor is mounted,

wherein a position of the bracket is determined with respect to the belt unit.

15. The image forming apparatus according to claim 14 ,

wherein the sensor is opposed to one of the plurality of rotators via the belt, and

wherein the position of the bracket is determined with respect to a shaft of the one of the plurality of rotators.

16. The image forming apparatus according to claim 14 , further comprising a bracket support to support the bracket,

wherein the adjuster is to adjust a position of at least one of the plurality of support portions and a position of the bracket support.

17. The image forming apparatus according to claim 16 , wherein the bracket support is a support shaft, and

wherein the bracket is pivotable on the support shaft.

18. The image forming apparatus according to claim 17 , wherein the support shaft is attached to the frame supporting the belt unit.

19. The image forming apparatus according to claim 17 , further comprising a frame shaft disposed at a position of the image forming apparatus different from the support shaft, the frame shaft to support the frame pivotably on the frame shaft.

20. The image forming apparatus according to claim 16 ,

wherein the bracket support is a support shaft, and

wherein the frame and the bracket are pivotable on the support shaft.