Image Forming Apparatus

An image forming apparatus configured to form an image on a transferred member by transferring a developer image onto the transferred member, comprising:

• a first photosensitive drum configured to carry a developer image to be transferred to the transferred member;
• a second photosensitive drum configured to carry a developer image to be transferred to the transferred member and disposed at a position shifted forward in the direction of movement of the transferred member with respect to the first photosensitive drum, and the second photosensitive drum having the same diameter as the first photosensitive drum;
• a first exposing unit configured to form an electrostatic latent image by exposing an outer peripheral surface of the first photosensitive drum by irradiating an exposure position with respect to the first photosensitive drum with a light beam;
• a second exposing unit configured to form an electrostatic latent image by exposing an outer peripheral surface of the second photosensitive drum by irradiating an exposure position with respect to the second photosensitive drum with a light beam;
• a first developing unit configured to supply developer to the first photosensitive drum to develop the electrostatic latent image formed on the first photosensitive drum;
• a second developing unit configured to supply the developer to the second photosensitive drum to develop the electrostatic latent image formed on the second photosensitive drum;
• a first transfer unit configured to cause the developer image formed on the first photosensitive drum to be transferred to the transferred member at a transfer position;
• a second transfer unit configured to cause the developer image formed on the second photosensitive drum to be transferred to the transferred member at a transfer position;
• a first drum gear configured to apply a rotational force to the first photosensitive drum;
• a second drum gear configured to apply a rotational force to the second photosensitive drum;
• and
• a first drive gear configured to apply a rotational force to the first drum gear and the second drum gear by meshing with the first drum gear and the second drum gear, wherein
• when a specific position on the outer peripheral surface of the first photosensitive drum selected arbitrarily is referred to as a first drum specific position,
• a tooth of the first drive gear meshed with the first drum gear when the first drum specific position is located at the exposure position is referred to as a first drive specific tooth, and
• when a portion of the outer peripheral surface of the second photosensitive drum located at the exposure position when the first drive specific tooth is meshed with the second drum gear is referred to as a second drum specific position,
• the first drive specific tooth meshes with the first drum gear when the first drum specific position is located at the transfer position, and the first drive specific tooth meshes with the second drum gear when the second drum specific position is located at the transfer position,
• when an arbitrarily selected tooth which serves as a reference is referred to as a reference tooth from among a plurality of teeth formed on the first drum gear,
• a tooth located at a position corresponding to the reference tooth of the first drum gear from among a plurality of teeth formed on the second drum gear is referred to as a reference tooth of the second drum gear, and
• when a plane angle obtained by dividing a value obtained by subtracting an axis-to-axis dimension of the first and second photosensitive drums from a peripheral length of the first photosensitive drum by the peripheral length of the first photosensitive drum is referred to as a first shift angle,
• the reference tooth of the second drum gear is shifted by the first shift angle from the transfer position assuming that the forward direction in the direction of rotation is a normal direction when the reference tooth of the first drum gear is located at the transfer position.