Patent ID: 8346114

Claim:
A power source for applying a voltage on an image forming unit of an image forming apparatus, the power source comprising: a voltage setting unit configured to set an output voltage; a voltage generation unit configured to output the voltage set by the voltage setting unit to a load; a feedback unit configured to detect the voltage output from the voltage generation unit to the load and feed back the detected voltage to the voltage setting unit; a current detection unit configured to detect a current value flowing in the load when the voltage set by the voltage setting unit is output to the load; and a control unit configured to switch between a constant current control operation and a constant voltage control operation, wherein the constant current control operation controls the voltage set by the voltage setting unit so that the current value detected by the current detection unit becomes a constant current, and wherein the constant voltage control operation controls the voltage set by the voltage setting unit so that the voltage output to the load becomes a constant voltage based on the voltage value that is fed back by the feedback unit, wherein the current detection unit detects a current value flowing in the load before discharge starts by applying a voltage to the image forming unit, and the current detection unit detects a sum of a current value flowing in the feedback unit and a current value flowing in the load after discharge starts by applying a voltage to the image forming unit.