| 摘要 |
PROBLEM TO BE SOLVED: To prevent phenomena such as scattering in a character image, a thrust and a drum memory in a halftone image. SOLUTION: A transfer bias voltage value to be impressed on transfer roller 5 by a high voltage power supply circuit 5d is controlled by a CPU 5e. In this case, a tip margin of a recording material P is detected first. Monitoring time of a resistance value of the recording material P is changed according to the quantity of the tip margin. For example, since resistance monitor of the recording material is performed by taking time when the quantity of the tip margin is large, control of the transfer bias voltage value with higher precision is enabled. Consequently, optimal control of transfer bias fixed voltage is enabled in an image print area (image formation area), relatively low transfer bias voltage is generated to the recording material P with low resistance value, high transfer bias voltage is generated to the recording paper P with high resistance value and the phenomenon such the scattering in the character image, the thrust and the drum memory in the halftone image is prevented. |
