| 主权项 |
1. An image forming apparatus comprising:
an image bearing member for bearing a toner image; an intermediary transfer member for carrying the toner image transferred from the image bearing member at a primary-transfer position; a transfer member, provided contactable to an outer peripheral surface of the intermediary transfer member, for transferring the toner image from the intermediary transfer member onto a recording material at a secondary-transfer position; a constant-voltage element, electrically connected between the intermediary transfer member and a ground potential, for maintaining a predetermined voltage by passing of a current therethrough; a power source for forming, by applying a voltage to the transfer member to pass the current through the constant-voltage element, both of a secondary-transfer electric field at the secondary-transfer position and a primary-transfer electric field at the primary-transfer position; a detecting portion for detecting the current passing through the transfer member; an executing portion for executing a test mode in which when no recording material exists at the secondary-transfer position, a test voltage is applied to the transfer member by the power source to detect the current by the detecting portion; and a controller for controlling, on the basis of the current detected by the detecting portion in the test mode, a voltage to be applied to the transfer member by the power source when the recording material exists at the secondary-transfer position, wherein the controller controls the test voltage applied by the power source so that the constant-voltage element maintains the predetermined voltage in at least an overlapping period between a period of the test mode and a period in which the toner image is transferred at the primary-transfer position. |
