| 摘要 |
PROBLEM TO BE SOLVED: To provide a copier that can suppress the occurrence of a failure in secondary transfer caused by a change in environment.SOLUTION: A copier comprises: toner image forming means that includes imaging units (2Y, M, C, and K) that form toner images on the surface of an intermediate transfer belt 61 having a multi-layer structure and optical writing units (1YM and 1CK); a secondary transfer power supply that outputs a transfer bias including a superimposition voltage in which a DC voltage is superimposed on an AC voltage in order to secondarily transfer the toner images on the intermediate transfer belt 61 to a recording sheet inserted into a secondary transfer nip formed by contact of the intermediate transfer belt 61 and a secondary transfer belt 77; and control means that controls an output from the secondary transfer power supply. The copier includes an environment sensor, and the control means performs bias switching processing of switching the secondary transfer bias between one including only the superimposed voltage and one including only the DC voltage on the basis of a result of detection performed by the environment sensor.SELECTED DRAWING: Figure 1 |
