Image forming apparatus

An image forming apparatus comprising:

• a transfer member configured to move in a movement direction;
• a first photosensitive drum disposed in contact with the transfer member at a first transfer position;
• a second photosensitive drum disposed in contact with the transfer member at a second transfer position, wherein the second photosensitive drum is arranged adjacent to and side by side with the first photosensitive drum in the movement direction, and the second transfer position is located downstream of the first transfer position in the movement direction;
• and
• a driving unit configured to drive the first photosensitive drum and the second photosensitive drum, wherein the driving unit includes:
• (i) a driving source,
• (ii) at least one driving force transmission gear configured to rotate by receiving a driving force from the driving source,
• (iii) a first drum gear that meshes with the at least one driving force transmission gear, wherein the first drum gear is configured to receive the driving force from the at least one driving force transmission gear to rotate in a first direction and drive the first photosensitive drum,
• (iv) a first coupling member provided at a first position of the first drum gear in the first direction, wherein the first coupling member is configured to rotate together with the first drum gear, and to rotate the first photosensitive drum while engaging with the first photosensitive drum,
• (v) a second drum gear that meshes with the at least one driving force transmission gear, wherein the second drum gear is configured to receive the driving force from the at least one driving force transmission gear to rotate in a second direction and drive the second photosensitive drum, and
• (vi) a second coupling member provided at a second position of the second drum gear in the second direction, wherein the second coupling member is configured to rotate together with the second drum gear, and to rotate the second photosensitive drum while engaging with the second photosensitive drum,
• wherein, assuming that a position where the first drum gear meshes with the at least one driving force transmission gear is a first meshing position and a position where the second drum gear meshes with the at least one driving force transmission gear is a second meshing position, a first angle from the first meshing position to the first transfer position in the first direction and a second angle from the second meshing position to the second transfer position in the second direction are different from each other, and
• wherein the second position of the second drum gear is shifted from a position corresponding to the first position of the first drum gear by a difference between the first angle and the second angle in a direction opposite of the second direction.