| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high-quality image at low cost by using a contact type transfer member for transfer, even if processing speed is high. SOLUTION: In this image forming device, an ion conduction type transfer roller is used, and a transfer bias control system is provided with three constant- current sources, whose constant current values are I0, I1 and I2 and one constant-voltage power source. When controlling the transfer bias in an ATVC system, ambient humidity is detected, and the constant-current power sources are selected in accordance with an environmental value E. By applying the constant current value I0 in the case of E=0 (ordinary environment), the constant current value I1 in the case of E=1 (low-humidity environment) and the constant current value I2 in the case of E=2 (high humidity environment), generated voltage at such a time Vt0, Vt01 or Vt02 is monitored. According to a function Vt0=F1(Vt01) and F2(Vt02), Vt0 in the case of E=1, 2 is calculated. In the above-mentioned way, Vt0 is found as amount obtained by measuring the resistance of a transfer roller in all the cases of E=0, 1, 2. The constant voltage bias VT is decided in accordance with a function VT=F3(Vt0), and VT is applied to the transfer roller so as to perform transfer. |
