Patent ID: 7919995

Claim:
A load controller, comprising: a first input circuit which detects that a drive instruction signal by an operation of a drive instructing unit is less or equal to a first input threshold value; a first constant current source activated in accordance with a detection by the first input circuit; a PWM signal supply unit that is activated by the first constant current source and supplies a PWM signal having a prescribed frequency and a duty ratio; a constant control signal supply unit that includes a failure detecting unit that detects failure of the first input circuit or the first constant current source, and that supplies a constant control signal during the failure of the first input circuit or the first constant current source which the failure detecting unit detects; a drive control unit that generates a PWM drive control signal in accordance with the PWM signal supplied from the PWM signal supply unit when the failure detecting unit does not detect the failure and generates a constant drive control signal in accordance with the constant control signal supplied from the constant control signal supply unit when the failure detecting unit detects the failure; and a load driving element that is controlled by the PWM drive control signal supplied from the drive control unit so as to drive a load by PWM control when the failure detecting unit does not detect the failure, and controlled by the constant drive control signal supplied from the drive control unit so as to drive the load by constant current control when the failure detecting unit detects the failure.