Patent ID: 7243527

Claim:
A sensing apparatus, comprising: a case having an opening part formed so as to communicate within outside of the case; a printed circuit board disposed at least partially within the case, and comprising a circuit unit; a noxious gas sensing part, being electrically connected with the circuit unit, for sensing noxious gas in external air flowing in through the opening portion, and for outputting a sensing signal; and a connector disposed at least partially within the case, one end thereof being directly connected with the circuit unit, and the other end thereof being configured to connect to and external device; wherein the circuit unit comprises: a protection circuit for detecting an inverse voltage and a surge that may be inputted into the circuit unit, and stopping an operation of the circuit unit as needed; a unification circuit having a first function of regulating a voltage supplied from the protection circuit, a second function of supplying the regulated voltage into the circuit unit, and a third function of supplying a heat to the noxious gas sensing part; and a signal circuit part generating a control signal on the basis of an outputted signal from the noxious gas sensing part, and transmitting the control signal into an outside device, wherein the signal circuit part comprises: a converter changing the outputted signal from the noxious gas sensing part to a frequency signal; a multifunction circuit for providing a first function of calculating a control signal on the basis of the frequency signal, a second function of matching to the calculated control signal, and a third function of detecting an overvoltage that may be generated while the circuit unit is operated, and stopping operation of the circuit unit based on the detected overvoltage; and a driving circuit for transmitting the matched control signal to the external device.