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US 8,505,354 B2Granted
Compensated gas detectors
AssigneeLife Safety Distribution AG
InventorsJaeJin Lee, JuWan Park, JoungHo Lim
Life of this patent
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Abstract
A compensated gas detector incorporates first and second pellistors combined with first and second resistors and an intervening switch. Control circuits can close the switch for normal gas detection. The switch can be opened to carry out diagnostic measurements. A compensation coefficient can be established in order to compensate outs from the pellistors due to mechanical damage thereto.
Claims6
A gas detector comprising:
- first and second pellistors, coupled in series;
- a controllable switch;
- first and second fixed resistors, coupled in series, wherein the pellisors are coupled to both the switch and to the resistors;
- and
- circuitry coupled to the switch, the pellistors and the resistors, wherein the circuitry places the switch into a conducting state to establish a gas concentration state and into an open circuit to establish a compensation state, wherein the circuitry independently measures respective resistance values of the first and second pellistors and stores measured resistance values on an on-going basis in a data storage unit and wherein the gas detector determines a concentration of the gas in the gas concentration state based upon resistance values of the first and second fixed resistors and the respective stored resistance values of the first and second pellistors.
2 more elements
Dependencies are inferred from the claim text.