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US 3,940,636 AGranted
Acoustic delay surface wave motion transducer systems with enhanced stability
AssigneeSperry Rand Corporation
InventorAvraham Perahia
Life of this patent
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Abstract
Transducer devices employing relative changes in the acoustical propagation characteristics of surface waves traveling on opposite surfaces of a thin elastic cantilever beam yield a measure of the degree of flexing or surface strain of the elastic member. A multiplexed phase comparison loop and signal processing circuit alternately cooperates with the opposite surface waves of the transducer to supply a digital output proportional to strain and relatively free of drift, mode locking, and other spurious interactions.
Claims10
Transducer means comprising:
- flexure means having first and second opposed flexible surface layer means for separately propagating respective first and second acoustic waves along first and second respective predetermined paths therein,
- first and second exciter means including switch means for alternately exciting and propagating said respective first and second acoustic waves along said first and second respective predetermined paths in response to respective alternate first and second exciter electric signals,
- first and second receiver means along said respective first and second predetermined paths for alternately receiving and converting said respective first and second acoustic waves into respective first and second successive receiver electric signals,
- voltage controllable oscillator means for alternately driving said first and second exciter means through said switch means,
- phase detector means responsive to said voltage controllable oscillator means and alternately responsive to said first and second receiver means,
- filter means responsive to said phase detector means for supply of a control voltage to said voltage controllable oscillator means, and
- signal processor means responsive to said voltage controllable oscillator means for deriving a measure of the flexure of said flexure means for supply to utilization means.
4 more elements
Dependencies are inferred from the claim text.