| 摘要 |
PROBLEM TO BE SOLVED: To optimally transfer an image regardless of the resistance value of recording material and an image pattern. SOLUTION: Transfer bias is corrected from VT0 to VT1 in accordance with a current (resistance value of recording material) flowing to a high-voltage power source circuit when the leading margin part of the recording material is positioned at a transfer nip part between a photoreceptor drum and a transfer roller. Generally speaking, time when the leading margin part is positioned at the transfer nip part is short (T3 to T4) and the resistance value of the recording material is not accurately detected, so that the transfer bias can not be appropriately corrected. Then, a transfer current is monitored further after the correction, whereby the transfer bias is corrected in accordance with the toner amount of the recording material. Thus, optimum constant-voltage control is performed thereafter. The toner amount of the recording material is obtained based on the exposure time of a laser beam scanner and a developing current during developing. |
