Image forming apparatus

An image forming apparatus comprising:

• a first image bearing member configured to bear a toner image;
• a first charging member configured to charge the first image bearing member;
• a second image bearing member configured to bear a toner image with a color different from the first image bearing member;
• a first development member configured to be in contact with or separated from the first image bearing member, and to develop an electrostatic latent image formed on the first image bearing member using toner, in a state of being in contact with the first image bearing member;
• a second development member configured to be in contact with or separated from the second image bearing member, and to develop an electrostatic latent image formed on the second image bearing member using toner, in a state of being in contact with the second image bearing member;
• an intermediate transfer member onto which a toner image borne by at least one of the first image bearing member or the second image bearing member is transferred;
• a first transfer member that is disposed at a position corresponding to the first image bearing member via the intermediate transfer member, and is configured to transfer a toner image onto the intermediate transfer member from the first image bearing member;
• a second transfer member that is disposed at a position corresponding to the second image bearing member via the intermediate transfer member, and is configured to transfer a toner image onto the intermediate transfer member from the second image bearing member;
• a transfer power source configured to apply voltage to the first transfer member and the second transfer member;
• a detection unit configured to detect currents flowing in the first transfer member and the second transfer member, in a case where voltage is applied to the first transfer member and the second transfer member from the transfer power source;
• and
• a control unit configured to select and execute either a first mode of transferring a toner image onto the intermediate transfer member from at least one of the first image bearing member or the second image bearing member in a first state in which the first transfer member and the second transfer member are in contact with the intermediate transfer member, or a second mode of transferring a toner image onto the intermediate transfer member from the first image bearing member in a second state in which the first transfer member is in contact with the intermediate transfer member and the second transfer member is separated from the intermediate transfer member,
• wherein the control unit determines which state of the first state and the second state is formed, based on a detection result obtained by the detection unit when the first image bearing member is charged by the first charging member, the first development member is separated from the first image bearing member, the second development member is separated from the second image bearing member, and voltage is applied to the first transfer member and the second transfer member from the transfer power source.