| 摘要 |
PROBLEM TO BE SOLVED: To provide an imaging device which is capable of accurately detecting a drop in the power supply voltage following the shut-off of an AC power supply and securely storing data which need to be retained even when the power supply is shut off. SOLUTION: An output voltage is detected by a voltage detecting means (step 10) and is loaded as a digital value from an A/D converter. Further, it is judged whether the detected value falls within a specified value range (step 11). When the judgement results are abnormal, the lowest duty is selected and is reflected on a PWM signal, which is, in turn, outputted to the converter (step 17). When the judgement results are normal, the duty reflected on the PWM signal stands above a predetermined upper limit value (step 12; Y). When the detected value of the output voltage is less than a target value (step 13; Y), the AC power supply is shut off and the input DC voltage of the converter drops and the PWM limit signal is asserted (step 14) on the judgement that the output voltage drops soon. |
