Ice detection system
First Claim
1. An ice detection system for detecting the state and thickness of water overlying a surface, comprising:
- a plurality of resonant circuits spaced at predetermined locations about an electrically conductive surface, each of said circuits consisting entirely of a respective cutout in said surface and having a preselected resonant frequency which varies in response to thickness of overlying ice and liquid water;
variable frequency generating means for generating a transmission signal which can be varied about the resonant frequency of each of said circuits to cause each of said circuits to generate a resonant frequency signal in response to said transmission signal;
receiver means tunable to the resonant frequency of each of said circuits, said receiver means including means for identifying the resonant frequency of each of said circuits and for determining the quality factor of each of said circuits from the resonant frequency signals produced by the respective circuits; and
processing means responsive to the identified resonant frequency and determined quality factor for each of said circuits, for determining the state and thickness of water overlying each of said circuits.
1 Assignment
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Accused Products
Abstract
A system and method for detecting the state and thickness of water accumulation on a surface incorporates a plurality of spaced, thin, electrically resonant circuits bonded to the surface and a radio frequency transmitter for exciting the circuits to resonance. A receiver detects the resonant signal from each circuit, determines the resonant frequency and quality factor of the circuit and correlates that information with predetermined data representing changes in resonant frequency and quality factor as a function of liquid water and ice accretion to thereby establish the state and thickness of water overlaying the circuits.
61 Citations
13 Claims
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1. An ice detection system for detecting the state and thickness of water overlying a surface, comprising:
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a plurality of resonant circuits spaced at predetermined locations about an electrically conductive surface, each of said circuits consisting entirely of a respective cutout in said surface and having a preselected resonant frequency which varies in response to thickness of overlying ice and liquid water; variable frequency generating means for generating a transmission signal which can be varied about the resonant frequency of each of said circuits to cause each of said circuits to generate a resonant frequency signal in response to said transmission signal; receiver means tunable to the resonant frequency of each of said circuits, said receiver means including means for identifying the resonant frequency of each of said circuits and for determining the quality factor of each of said circuits from the resonant frequency signals produced by the respective circuits; and processing means responsive to the identified resonant frequency and determined quality factor for each of said circuits, for determining the state and thickness of water overlying each of said circuits. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of detecting ice accretion on a surface of electrically conductive material having resonant circuits implanted thereon entirely by removal of portions of said material, each of said portions being of a predetermined pattern, each respective circuit being tuned to a separate preselected resonant frequency, respectively, said method comprising the steps of:
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transmitting an RF signal which varies over a predetermined range including the resonant frequency of each of the resonant circuits so as to excite each of the circuits at its own respective resonant frequency; detecting signals generated by at least some of the resonant circuits excited by the transmitted RF signal; determining any deviation in the frequency of each detected signal from the preselected resonant frequency for the circuit generating said each detected signal; computing the quality factor of each of said at least some resonant circuits from the detected signals generated thereby; and determining the state and thickness of a layer of water overlying any of said at least some resonant circuits from the frequency of the detected signals and the respective quality factors thereof. - View Dependent Claims (8)
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9. An ice detection system for an aircraft propeller blade comprising:
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a plurality of thin film resonant circuits bonded to an intermediate subsurface layer of a propeller blade and overlayed by a nonconductive surface protective coating, each of said resonant circuits being tuned to a preselected frequency; RF generating means for generating a fixed frequency pilot signal and a swept frequency signal, said swept frequency signal ranging through said preselected frequency; receiver means for detecting RF signals over a range including said preselected frequency, said receiver means being responsive to receipt of said pilot signal reflected from said propeller blade for signaling said RF generating means to initiate said swept frequency signal, said receiver means being further responsive to receipt of resonant frequency signals generated by said resonant circuits in response to said swept frequency signal for determining the resonant frequency and quality factor of the resonant circuits; and processing means for determining thickness of ice on said propeller blade from the determined resonant frequency and quality factor. - View Dependent Claims (10, 11, 12, 13)
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Specification