Environmental hazard sensor
AssigneeDetector Electronics Corporation
InventorsMorton Lee Schlesinger, Anthony Charles Young, John Dee King
Life of this patent
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Abstract
An apparatus for sensing a constituent in an environment including a sensor circuit and a suppression circuit. The sensor circuit has a sensor element and an operating state control element. The sensor element senses the constituent by presenting an electrical parameter which varies as a function of a degree of the constituent. The control element maintains the sensor at a preferred operating state. A detected electrical parameter of said sensor element is subject to error resulting from a leakage of electrical current between the control element and the sensor element. The suppression circuit reduces or stops the leakage to reduce the error.
Claims19
An apparatus for sensing a constituent in an environment, said apparatus comprising:
- a. a sensor circuit having:
- i. a sensor element for sensing said constituent by presenting an electrical parameter which varies as a function of a degree of said constituent, said sensor element having a preferred operating state;
- ii. an operating state control element for maintaining said preferred operating state;
- iii. wherein a detected electrical parameter of said sensor element is subject to error resulting from a leakage of electrical current between said control element and said sensor element;
- b. a suppression circuit for inhibiting said leakage to reduce said error by equalizing voltages of the sensor element and the operating state control when the electrical parameter is measured.
A method of measuring a gas with a sensor having a detection circuit and a heating circuit, the method comprising:
- connecting the detection circuit to a fixed voltage source, the detection circuit having an electrical parameter which varies as a function of a concentration of said gas, the detection circuit being configured to operate when a temperature of the detection circuit is maintained at a predetermined temperature;
- connecting the heater circuit to a variable voltage source to generate heat to maintain the temperature of the detection circuit at the predetermined temperature;
- periodically disconnecting the variable voltage source from the heater circuit and connecting the fixed voltage source to the heater circuit;
- and
- measuring the electrical parameter of the detection circuit when the fixed voltage source is connected to the heater circuit.
An apparatus for sensing a subject of interest in an environment, said apparatus comprising:
- a sensor element having a resistance that varies in response to exposure to the subject of interest, the sensor element being configured to receive a sample and to output an electrical signal affected by the resistance of the sensor element,
- a controller configured to maintain an operating property of the sensor element;
- a first voltage source configured to drive the sensor element to a first voltage;
- a second voltage source configured to drive the controller to a second voltage, the second voltage being significantly greater than the first voltage;
- and
- an suppression element configured to disconnect the controller from the second voltage source and to drive the controller to about the first voltage.
Dependencies are inferred from the claim text.