US 5,191,791 A · Piezoelectric sensor

Abstract

The change in capacitance of a sensor is linearly proportional to ice thickness provided that the ice thickness is significantly less than the distance between the conductive electrodes. By employing sensors with different electrodes, the sensitivity to ice may be traded off against the ability to measure greater ice thickness. A sensor with small spacing between electrodes will exhibit a large change in capacitance when covered by a thin layer of ice, however, the capacitance change will be linear only for very thin layers of ice. A sensor with greater spacing between electrodes is less sensitive to ice accretion but has a correspondingly greater ice thickness measurement range. Accordingly, sensor (55) is relatively sensitive and is employed to determine whether or not ice or water is present. This is accomplished by circuit (60) determini STATEMENT REGARDING GOVERNMENT FUNDED RESEARCH This invention was made with Government support under NAS1-18421, NAS2-12890 and NAS3-25618 awarded by the National Aeronautics and Space Administration. The Government has certain rights in this invention.

Claims14

Dependent claims

An apparatus for measuring localized ice thickness comprising:

an ice presence sensor having a first metallization layer facing towards an environment, a second metallization layer, and a dielectric layer between said first and second metallization layers, said second metallization layer being greater in surface area than said first metallization layer, wherein existence of ice in an area surrounding said first metallization layer causes a capacitance value associated with said ice presence sensor to change;
and
an ice thickness sensor having a dielectric layer, and having first and second metallization layers located on one side of said dielectric layer and facing towards the environment, wherein existence of ice in an area between said first and second layers of said ice thickness sensor causes a capacitance value associated with said ice thickness sensor to change.

Dependencies are inferred from the claim text.

Piezoelectric sensor

Life of this patent

Piezoelectric sensor

Life of this patent

Abstract

Claims14