Transducer in-situ testing apparatus and method
First Claim
1. A self testing transducer circuit comprising:
- (a) a transducer characterized by a self resonant frequency;
(b) an amplifier connected to the transducer amplifying the output of the transducer;
(c) a signal source coupled to the output of the transducer and the input of the amplifier, the signal source generating a test signal having a spectrum at least overlapping the self resonant frequency of the transducer; and
(d) an analyzer connected to an output of the amplifier for measuring the response of the transducer to the test signal and characterizing at least one parameter of the transducer.
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Abstract
The present invention provides an apparatus and method for in-situ testing of transducers, and more particularly to the testing of piezoelectric transducers including piezoelectric accelerometers. Circuits, measurement techniques, and interpretative algorithms to enable in-situ testing of piezoelectric accelerometers are described. Accelerometers that employ a piezoelectric material to convert mechanical strains into electronic signals are reciprocal electromechanical transducers. In such transducers the electrical output impedance of the sensor is dependent upon the electrical and mechanical parameters of the sensor. The procedure described in this disclosure includes methods of measuring the transducer electrical output impedance as a function of frequency and the extraction of the electrical and mechanical transducer parameters from the measured data. The measured values of the transducer parameters may be interpreted to provide an indication of the operational status of the transducer. In addition to allowing verification of correct transducer performance, a range of failure conditions and degradations may be inferred from the transducer parameter values.
332 Citations
25 Claims
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1. A self testing transducer circuit comprising:
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(a) a transducer characterized by a self resonant frequency;
(b) an amplifier connected to the transducer amplifying the output of the transducer;
(c) a signal source coupled to the output of the transducer and the input of the amplifier, the signal source generating a test signal having a spectrum at least overlapping the self resonant frequency of the transducer; and
(d) an analyzer connected to an output of the amplifier for measuring the response of the transducer to the test signal and characterizing at least one parameter of the transducer. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A test method comprising;
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(a) providing a transducer capable of measuring one or more parameters;
(b) connecting the transducer to an amplifier for amplifying an output of the transducer;
(c) generating a test signal having a spectrum at least overlapping a self-resonant frequency of the transducer;
(d) coupling the test signal to the transducer and the input of an amplifier;
(e) amplifying the output of the transducer with the amplifier; and
(f) analyzing the signal created by the sensor transducer and characterizing at least one parameter. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A testing method comprising:
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(a) generating a test signal from a signal source having an output spectrum overlapping a self-resonant frequency of a transducer capable of measuring one or more parameters;
(b) coupling the test signal to the transducer and the input of an amplifier;
(c) amplifying a signal created by the sensor transducer in response to the test signal; and
(d) analyzing the signal created by the sensor transducer and characterizing at least one parameter of the sensor. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A self testing transducer circuit comprising:
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a transducer characterized by a self resonant frequency;
an amplifier comprising a charge mode amplifier, such that the transducer is connected to a sense node of the amplifier, amplifying the output of the transducer;
a signal source coupled to the output of the transducer and a reference node of the amplifier, the signal source generating a test signal having a spectrum at least overlapping the self resonant frequency of the transducer; and
an analyzer connected to an output of the amplifier for measuring the response of the transducer to the test signal and characterizing at least one parameter of the transducer.
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24. A sensor testing method comprising:
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generating a test signal from a signal source having an output spectrum overlapping a self-resonant frequency of a transducer of the sensor;
coupling the test signal to the transducer and the input of an amplifier;
amplifying a signal created by the sensor in response to the test signal; and
analyzing the signal created by the sensor and characterizing at least one parameter of the sensor, comprising analyzing a sensor'"'"'s total output impedance as a function of frequency.
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25. A sensor testing method comprising:
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generating a test signal from a signal source having an output spectrum overlapping a self-resonant frequency of a transducer of the sensor;
coupling the test signal to the transducer and the input of an amplifier;
amplifying a signal created by the sensor in response to the test signal;
analyzing the signal created by the sensor and characterizing one or more parameters of the sensor corresponding to and derived from the total output impedance; and
further comprising analyzing a sensor'"'"'s total output impedance as a function of frequency.
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Specification