Integrated semiconductor resistance temperature sensor and resistive heater
AssigneeRosemount Inc.
InventorsFred C. Sittler, Robert C. Bohara
Life of this patent
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Abstract
An integrated sensing device includes a resistance temperature sensor formed in a semiconductor substrate and a resistance heater which is formed on an insulating layer which covers the surface of the semiconductor substrate. The resistance heater has a low temperature coefficient of resistivity and is positioned adjacent the resistance temperature sensor so the current flow through the resistance heater will generate heat which is transferred through the insulating layer to the resistance temperature sensor. The sensing device is applicable to a variety of sensing systems, such as mass flow measurement systems, dew point detection systems, and frost detection systems.
Claims15
A sensor comprising:
- a semiconductor substrate;
- an electrical insulating layer covering a first surface of the substrate;
- a semiconductor resistance temperature sensor formed in the semiconductor substrate adjacent the first surface of the substrate;
- a film resistance heater having a low temperature coefficient of resistivity formed on the insulating layer adjacent the temperature sensor;
- first contact means for providing electrical connection to the temperature sensor;
- and
- second contact means for providing electrical connection to the resistive heater.
A frost sensor comprising:
- a detector including a resistance heater having a low temperature coefficient of resistivity and a temperature sensor having a higher temperature coefficient of resistivity positioned adjacent one another;
- means for positioning the detector adjacent a surface susceptible to frost accumulation;
- means for applying an electrical signal to the heater to heat the detector to a temperature at least equal to a melting point of frost for melting frost formed on the detector;
- and
- means responsive to changes in resistance of the temperature sensor as a result of heat produced by the heater for deriving a signal which is a function of frost accumulation on the detector, based upon the resistance of the temperature sensor exhibiting an insignificant change during a time period in which the frost formed on the detector is melted.
Dependencies are inferred from the claim text.