Patent ID: 7423355

Claim:
A power controller that controls power of an apparatus provided with first and second backup power supplies for a power supply, comprising: a power failure state determination unit that determines the power failure state of the power supply; a power supply installation state determination unit that determines the installation states of the first and second backup power supplies of the apparatus; and a power control unit that, in case the power failure state is determined by the power failure state determination unit, selects the first or the second backup power supplies based on determination result by the power failure state determination unit and determination result by the power supply installation state determination unit; wherein: the power failure state determination unit determines plural power failure states corresponding to the usage pattern of the first and second backup power supplies based on the installation state of the first and second backup power supplies which is determined by the power supply installation state determination unit; the power failure state determination unit uses time of a timer that clocks time together with the power supply voltage monitoring result; and clocks a period of time during which the power supply voltage becomes less than a predetermined value using the timer, and determines a predetermined power failure state based on thus clocked period of time; and the power controller controls the first and second backup in an optimal manner so as to backup the power supply upon power failure thereof.