Patent ID: 7667941
Filing Date: 2010-02-23
Classification: H02M

Abstract:
1. A power supply circuit protecting method in an apparatus including a power supply circuit for converting an ac input voltage into a prescribed output voltage and an output operation circuit for performing a prescribed operation by adopting the output voltage as input, said power supply circuit protecting method comprising: detecting a current value of the power supply circuit; judging presence or absence of abnormality at a first level in a supply voltage to the power supply circuit based on the detected current value, the abnormality at the first level requiring the output operation circuit to be stopped; judging presence or absence of abnormality at a second level, lower than the first level, in the supply voltage to the power supply circuit based on the detected current value; stopping the output operation circuit in response to a judgment that the abnormality at the first level in the supply voltage is present; and changing operating conditions of the output operation circuit in response to a judgment that the abnormality at the second level in the supply voltage is present.