Patent ID: 7028530

Claim:
A gas detector comprising: a high-temp exothermic detector unit having a high-temp exothermic gas sensor element and a high-temp exothermic temperature sensor element, each of the sensor elements made of a resistor of which a resistance changes responsive to temperature, the high-temp exothermic gas sensor element exposed to a gas being detected, and the high-temp exothermic temperature sensor element sealed in an unperforated casing filled with dry air and maintained to generate heat to a temperature substantially equal to a self-heating temperature of the high-temp exothermic gas sensor element as measured in dry air; and a low-temp exothermic detector unit having a low-temp exothermic gas sensor element and a low-temp exothermic temperature sensor element, each of the sensor elements made of a resistor of which a resistance changes responsive to temperature, the low-temp exothermic gas sensor element exposed to the gas being detected, and the low-temp exothermic temperature sensor element sealed in another unperforated casing filled with dry air and maintained to generate heat to a temperature substantially equal to a self-heating temperature of the low-temp exothermic gas sensor element as measured in dry air, wherein the self-heating temperature of the high-temp exothermic gas sensor element and the high-temp exothermic temperature sensor element of the high-temp exothermic detector unit is set to be different from the self-heating temperature of the low-temp exothermic gas sensor element and the low-temp exothermic temperature sensor element of the low-temp exothermic detector unit as measured in the dry air, and further wherein the gas detector performs processes of: converting resistance values of the individual gas sensor elements that change responsive to hydrogen concentration, humidity and an ambient temperature, and resistance values of the individual temperature sensor elements that change responsive to the ambient temperature into electrical gas-level outputs corresponding to the hydrogen concentration and the humidity; normalizing the gas-level outputs gained from the individual detector units by using a hydrogen sensitivity conversion factor obtained under a known level of hydrogen concentration; obtaining a humidity-level output derived as a difference between the normalized outputs; and producing outputs representing levels of the hydrogen concentration and the humidity by correcting the normalized outputs with a humidity-level correction formula established through a correlation of a humidity-level correction value obtained from the humidity-level output gained under an environment of known humidity level and the individual normalized outputs responsive to the humidity.