Alternating current input voltage detection circuit

An alternating current input voltage detection circuit that is provided at an inside or outside of a device rectifying an alternating current input voltage supplied from an alternating current power supply by a diode rectification circuit having a bridge configuration to detect the alternating current input voltage and output a voltage detection signal, the alternating current input voltage detection circuit comprising:

• a first voltage waveform detection circuit that detects a voltage waveform of one alternating current input terminal of the diode rectification circuit, based on a ground potential corresponding to a negative direct current output of the device, wherein a first detection voltage waveform is output from the first voltage waveform detection circuit;
• a second voltage waveform detection circuit that detects a voltage waveform of the other alternating current input terminal of the diode rectification circuit, based on the ground potential corresponding to a negative direct current output of the device, wherein a second detection voltage waveform is output from the second voltage waveform detection circuit;
• a first subtraction circuit that subtracts the second detection voltage waveform from the first detection voltage waveform and generates a first detection voltage waveform signal, in which waveform distortions generated in the vicinity of a zero voltage of the first detection voltage waveform and the second detection voltage waveform are eliminated;
• a second subtraction circuit that subtracts the first detection voltage waveform from the second detection voltage waveform and generates a second detection voltage waveform signal, in which waveform distortions generated in the vicinity of a zero voltage of the first detection voltage waveform and the second detection voltage waveform are eliminated;
• a first adding circuit that adds an output from the first subtraction circuit and an output from the second subtraction circuit;
• and
• a voltage waveform generation circuit that:
• outputs a voltage waveform signal from the first adding circuit as the voltage detection signal.