| 摘要 |
PROBLEM TO BE SOLVED: To obtain a good image while conducting a high speed image forming by setting an optimum process condition such as a transfer bias for individual transfer materials having different kinds and characteristics. SOLUTION: A pretransfer electrifying roller 26 is provided at the upstream side of a first color image forming section of a carrying belt 14. A detection bias is applied to a tip margin section of a transfer material P from a constant voltage controlled power supply 32A through the roller 26. The value of the current is detected by a detecting means 33A at that time and the kind of the material P is discriminated from the detection result and a preliminary electrifying bias is set. Moreover, a detection bias is applied to the tip margin section of the material from a constant voltage controlled power supply 32Y through a first color transfer blade 4Y and the current value is detected by a detecting means 33Y. Based on the detection result, the kind of the material P is further discriminated and a transfer bias is set based on the detection results of the means 33A and 33Y. |
