| 摘要 |
PROBLEM TO BE SOLVED: To provide a protection mechanism of a load which is advantageous in space or costs with no exclusive voltage detection circuit. SOLUTION: A power unit loaded on an image forming apparatus: includes a switching element for supplying a power to a load whose rated voltage is set; and a generation part for generating a pulse signal for driving a switching element according to an input voltage. Furthermore, the power unit includes: a duty detection part for detecting the duty of a pulse signal output from the generation part; and a decision part for deciding an input voltage from the detected duty. Furthermore, the power unit includes a switching part for switching a power supply means to a load according to the decided input voltage. COPYRIGHT: (C)2009,JPO&INPIT
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