Patent ID: 8463149

Claim:
An image forming apparatus comprising: a belt member configured to bear a recording material or a toner image; a first image bearing member; a first transfer member configured to transfer a toner image from the first image bearing member toward the belt member; a second image bearing member; a second transfer member configured to transfer a toner image from the second image bearing member toward the belt member; a first sensing portion configured to sense a current passing through the first transfer member when a voltage is applied to the first transfer member; a second sensing portion configured to sense a current passing through the second transfer member when a voltage is applied to the second transfer member; and a controller configured to execute a first mode in which an image can be formed when the belt member is in contact with the first and second image bearing members and a second mode in which an image can be formed when the belt member is separated from the first image bearing member and is in contact with the second image bearing member; wherein, with a predetermined timing, the first sensing portion senses a first current when the belt member is in contact with the first and second image bearing members, and the second sensing portion senses a second current when the belt member is separated from the first image bearing member and is in contact with the second image bearing member, and the controller is configured to set a voltage to be applied to the first transfer member during execution of the first mode, based on a current sensed by the second sensing portion in the second mode after the predetermined timing, the first current, and the second current.