PURPOSE: To form optimum images at all times by detecting the environmental state of a transfer means at specific timing and setting and controlling a desired transfer bias at least once.
CONSTITUTION: When environmental information on the transfer means 10a is detected at specific timing after the start of a printing sequence, a transfer bias setting means 26a sets the desired transfer bias in the transfer means 10a ≥1 time to set the best desired transfer bias for the environmental state of the transfer means 10a at all times. Namely, once code information is inputted to a microprocessor 17, a prefeed instruction is sent out to bring the transfer roller 10a of a photosensitive drum 2 under constant-current control and a voltage which is generated at this time is held and applied at the time of printing. For example, when the transfer roller 10a is brought under the constant- current control, a voltage which is about 2.5 KV in normal environment, about 3.0 KV in low-temperature, low-humidity environment, or about 2.0 KV in high- temperature, high-humidity environment is generated to obtain an excellent transfer image in corresponding environment. Consequently, even if the environment changes, the best developed image which has no transfer defect can be transferred.
GOTO MASAHIRO
INOUE TAKAHIRO
KATO JUNICHI
TSUKIDA TATSUICHI
YAMADA HIROMICHI
SUWA KOICHI
OSHIMA MASAKI
TAKANO MANABU
