Patent ID: 8606136

Claim:
A voltage detection device comprising: a first voltage detection part that detects a first ratio that is a ratio of a time period to one cycle of an alternative voltage of an AC power supply to a time period in which the alternative voltage is equal to or more than a first threshold value; a second voltage detection part that detects a second ratio that is a ratio of a second time period to the one cycle of the alternative voltage of the AC power supply to a second time period in which the alternative voltage is equal to or more than a second threshold value and less than the first threshold value; and a voltage determination unit that determines whether the voltage of the AC power supply is a first commercial voltage or a second commercial voltage lower than the first commercial voltage based on the first ratio and the second ratio, wherein in a case where the first ratio is less than the first threshold value and the second ratio is less than the second threshold value, the voltage determination unit determines that the voltage of the AC power supply is the second commercial voltage, and in a case where the first ratio is more than the first threshold value and the second ratio is more than the second threshold value, the voltage determination unit determines that the voltage of the AC power supply is the first commercial voltage.