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OwnerPaul F. Bennewitz, Matt C. Bennewitzinventors
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Sensor and method of fabricating a sensor for detecting relative humidity with a substantially linear response from 0% to 100% and also detecting temperature. The sensor utilizes a unique essentially pure Al.sub.2 O.sub.3 layer which has a disordered crystalline structure and a density gradient which varies from a low density at its lower surface to a higher density at its upper surface which together produce the desired linear response to relative humidity. The sensor is employed as a three-terminal semiconducting device which is biased with d.c. current, allowing implementation with standard ICs and LSI circuitry. Application of a biasing current on the top electrode allows the RH sensor to be operated simultaneously as a temperature sensor. Also disclosed is a relative humidity detector system for adjusting sensitivity of the sensor for changes in environmental temperature so as to provide a true linear relative humidity response. Periodic discharge of the d.c. biasing signal increases an already long calibration period. Additionally, use of a constant resistance biasing circuit further extends the calibration period.
A relative humidity detector system for generating an output signal which varies linearly with relative humidity, essentially independent of changes in surrounding environmental temperature, comprising:
A relative humidity detector system for producing a substantially linear response to changes in relative humidity independent of changes in environmental temperature comprising:
A relative humidity detector system for increasing the calibration period of a relative humidity sensor comprising:
A relative humidity detector system for lengthening the calibration period of a relative humidity sensor comprising:
A method of increasing the calibration period of a relative humidity sensor formed from an essentially pure layer of Al.sub.2 O.sub.3 having a variable density gradient between a top and bottom electrode, said method comprising the steps of:
Dependencies are inferred from the claim text.