Image forming apparatus effectively producing quality color image without causing color slippage

1. An image forming apparatus comprising:

a plurality of process cartridges each of which includes,

an image carrier configured to form an image intermediately,

a drive transfer member engaged with the image carrier,

a drive mechanism configured to drive to rotate the image carrier via the drive transfer member,

a marking member mounted on the drive transfer member and configured to indicate a rotational position of the drive transfer member,

a detector configured to detect the rotational position by detecting the marking member,

a balancer mounted on the drive transfer member configured to match a weighted center of the drive transfer member with a shaft center of the image carrier, the balancer and marking member being mounted on opposite front and back sides of the drive transfer member, and

a controller configured to adjust rotational phases of the image carriers based on results detected by the detector.

2. The image forming apparatus according to claim 1 , wherein the balancer is mounted on a different circumference of the drive transfer member from a circumference on which the marking member is mounted.

3. The image forming apparatus according to claim 1 , wherein the balancer has a different height than of the marking member.

4. The image forming apparatus according to claim 1 , wherein the balancer has a different thickness than of the marking member.

5. The image forming apparatus according to claim 1 , wherein the balancer is made of a different material than of the marking member.

6. The image forming apparatus of claim 1 , wherein the balancer comprises:

a plurality of strengthening ribs configured to strengthen the drive transfer member,

wherein at least one of the strengthening ribs has a different height from a height of other strengthening ribs so that a weighted center of the drive transfer member matches with a shaft center of the image carrier.

7. The image forming apparatus of claim 1 , wherein the balancer comprises:

a plurality of strengthening ribs configured to strengthen the drive transfer member,

wherein at least one of the strengthening ribs has a different thickness than a thickness of other strengthening ribs so that a weighted center of the drive transfer member matches with a shaft center of the image carrier.

8. The image forming apparatus according to claim 1 , wherein each process cartridge which includes the image carrier is removable.

9. The image forming apparatus according to claim 1 , wherein the marking member is a first feeler member protruding from the drive transfer member and the balancer is a second feeler member protruding from the drive transfer member and mounted on a different circumference of the drive transfer member from a circumference on which the first feeler member is mounted.

10. The image forming apparatus according to claim 1 , wherein the marking member is a first feeler member protruding from the drive transfer member and the balancer is a second feeler member having a different height than of the first feeler member.

11. The image forming apparatus according to claim 1 , wherein the marking member is a first feeler member protruding from the drive transfer member, and the balancer is a second feeler member protruding from the drive transfer member and having a different thickness than of the first feeler member.

12. The image forming apparatus according to claim 1 , wherein the marking member is a first feeler member protruding from the drive transfer member and the balancer is a second feeler member protruding from the drive transfer member and mounted on another side of the drive transfer member from which the first feeler member is mounted.

13. The image forming apparatus according to claim 1 , wherein the marking member is a first feeler member protruding from the drive transfer member, and the balancer is a second feeler member protruding from the drive transfer member and made of a different material than of the first feeler member.

14. The image forming apparatus of claim 1 , wherein the marking member is a first feeler member protruding from the drive transfer member and the balancer comprises:

a plurality of strengthening ribs configured to strengthen the drive transfer member,

wherein at least one of the strengthening ribs has a different height from a height of other strengthening ribs so that a weighted center of the drive transfer member matches with a shaft center of the image carrier.

15. The image forming apparatus of claim 1 , wherein the marking member is a first feeler member protruding from the drive transfer member and the balancer comprises:

a plurality of strengthening ribs configured to strengthen the drive transfer member,

wherein at least one of the strengthening ribs has a different thickness than a thickness of other strengthening ribs so that a weighted center of the drive transfer member matches with a shaft center of the image carrier.

16. An image forming apparatus comprising:

a plurality of process cartridges each of which includes,

image camer means for forming an image intermediately,

drive transfer means engaged with the image carrier means,

driving means for driving to rotate the image carrier means via a drive transfer means,

marking means mounted on the drive transfer means for indicating a rotational position of the drive transfer means,

detecting means for detecting the rotational position by detecting the marking means,

balancing means for matching a weighted center of the drive transfer means with a shaft center of the image carrier means, the balancing means and marking means being mounted on opposite front and back sides of the drive transfer member, and

control means for adjusting rotational phases of the plurality of image carrier means based on results detected by the detecting means.