Patent ID: 7080280

Claim:
A power failure sensing device comprising: a power failure sensing circuit which outputs a power failure sensing signal to an internal electrical power source of a use apparatus provided to interlock an external device when an output voltage from an internal electrical power source falls below a predetermined level, wherein, said power failure sensing circuit of said use apparatus provides an outside signal input part receiving a power failure signal from said external device and; a power failure signal output part which outputs a final power failure sensing signal in response to at least one signal of an external power failure signal and an interior power failure signal, wherein said external power failure signal is generated from said outside signal input part when said external device has a power failure, said interior power failure signal being generated when said use apparatus has a power failure, wherein said use apparatus is a card reader and said external device is a host device which controls the card reader, the card reader is provided with an internal electrical power source and an outside signal input part which receives a power failure signal in the host device, wherein the card reader outputs a final power failure sensing signal in response to at least one of the power failure signal in the host device, which controls the card reader, and the internal power failure signal of the internal electrical power source of the card reader.