US3878477A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic surface wave oscillator force-sensing devices
Assignee: HP Inc
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Filing: 1974-01-08
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Granted: 1975-04-15
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Expires: 1994-01-08
Abstract
Abstract An acoustic surface wave oscillator is employed as a forcesensing device. Dual acoustic surface wave oscillators coupled to a single substrate of piezoelectric material which inversely change their respective frequencies in response to a force applied normal to the surface of the substrate comprise a highsensitivity, temperature-compensated force-sensing device. The outputs of the oscillators are applied to an electronic mixer circuit to produce a difference frequency output signal which is a function of the applied force. Other configurations utilizing the force-sensing properties of acoustic surface wave oscillators are disclosed.
Inventors
- 👤 J Fleming Dias
- 👤 Henry E Karrer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:46
CPC Classifications
G; G10; G10K; G10K11/00; G10K11/36; G01; G01L; G01L1/00; G01L1/16; G01L1/162; G01L1/165; G01L9/00; G01L9/0001; G01L9/0008; G01L9/0022; G01L9/0025; Y; Y10; Y10S; Y10S73/00; Y10S73/04
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
175 words
A dual acoustic surface wave oscillator comprising: a substrate of piezoelectric material having a first surface and a second surface; two transducers disposed a predetermined distance apart on the first surface of the piezoelectric material forming a first transducer set for propagating a first acoustic surface wave thereon; two transducers disposed a predetermined distance apart on the second surface of the piezoelectric material forming a second transducer set for propagating a second acoustic surface wave thereon; a first amplifier connected to the first transducer set forming a first acoustic surface wave oscillator having an output terminal for coupling the output signal therefrom; a second amplifier connected to the second transducer set forming a second acoustic surface wave oscillator having an output terminal for coupling the output signal therefrom; and mixing means, connected to the output terminals of the first and second acoustic surface wave oscillators, for combining the output signals therefrom to form a resultant output signal having a frequency representing the difference in the frequency of the first and second acoustic surface wave oscillators.
Claim 2
Dependent Claim
175 words
A dual acoustic surface wave oscillator comprising: a substrate of piezoelectric material having a first surface and a second surface; two transducers disposed a predetermined distance apart on the first surface of the piezoelectric material forming a first transducer set for propagating a first acoustic surface wave thereon; two transducers disposed a predetermined distance apart on the second surface of the piezoelectric material forming a second transducer set for propagating a second acoustic surface wave thereon; a first amplifier connected to the first transducer set forming a first acoustic surface wave oscillator having an output terminal for coupling the output signal therefrom; a second amplifier connected to the second transducer set forming a second acoustic surface wave oscillator having an output terminal for coupling the output signal therefrom; and mixing means, connected to the output terminals of the first and second acoustic surface wave oscillators, for combining the output signals therefrom to form a resultant output signal having a frequency representing the difference in the frequency of the first and second acoustic surface wave oscillators.
Claim 3
Dependent Claim
30 words
The dual acoustic surface wave oscillator of claim 1 wherein: the piezoelectric material has plane parallel surfaces on which the transducer sets are disposed; and the transducers include interdigital fingers.
Claim 4
Dependent Claim
119 words
The dual acoustic surface wave oscillator of claim 1 wherein: each transducer set is offset on its respective surface along the direction of wave propagation such that no transducer is directly opposite another transducer of the other set; a first set of two grounding planes is disposed on the second surface of the piezoelectric material in a position directly opposite the first set of two transducers for reducing signal interaction between the first and second set of transducers; and a second set of two grounding planes is disposed on the first surface of the piezoelectric material in a position directly opposite the second set of two transducers to reduce signal interaction between the second and first set of transducers.
Claim 5
Dependent Claim
121 words
The dual acoustic surface wave oscillator of claim 1 wherein: the transducers of the set disposed on the first surface of the substrate for propagating an electromagnetic signal thereon have a frequency response generally characterized by the mathematical relation Y sin x/x; and the transducers of the set disposed on the second surface of the substrate for propagating an electromagnetic signal thereon have a frequency response generally characterized by the mathematical relation Y sin x/x, where y amplitude and x frequency; said first surface transducer set having a frequency of maximum amplitude equal to a frequency of minimum amplitude of the second surface transducer set for reducing signal interaction between transducer sets of the first and second surfaces of the substrate.
Claim 6
Dependent Claim
151 words
A force-sensing device employing an acoustic surface wave oscillator comprising: a substrate of piezoelectric material having a surface on which transducers may be disposed; mounting means connected to the substrate for rigidly holding the substrate to respond to a force applied thereto; two transducers disposed a predetermined distance apart forming a transducer set on the surface of the substrate for propagating an acoustic surface wave thereon; an amplifier connected to the transducer set to form an acoustic surface wave oscillator having an output signal frequency that varies in response to changes in the physical characteristics of the substrate and the distance between the transducers of the transducer set; and output means connected to an output of the acousTic surface wave oscillator for receiving an output signal therefrom; said physical characteristics of the substrate and distance between transducers of the transducer set changing in response to the force applied to the substrate.
Claim 7
Dependent Claim
151 words
A force-sensing device employing an acoustic surface wave oscillator comprising: a substrate of piezoelectric material having a surface on which transducers may be disposed; mounting means connected to the substrate for rigidly holding the substrate to respond to a force applied thereto; two transducers disposed a predetermined distance apart forming a transducer set on the surface of the substrate for propagating an acoustic surface wave thereon; an amplifier connected to the transducer set to form an acoustic surface wave oscillator having an output signal frequency that varies in response to changes in the physical characteristics of the substrate and the distance between the transducers of the transducer set; and output means connected to an output of the acousTic surface wave oscillator for receiving an output signal therefrom; said physical characteristics of the substrate and distance between transducers of the transducer set changing in response to the force applied to the substrate.
Claim 8
Dependent Claim
88 words
The acoustic surface wave force-sensing device of claim 5 wherein: the piezoelectric substrate is generally elongated in shape in which the planar surfaces have a longitudinal dimension greater than a width dimension; the elongated piezoelectric substrate is oriented in the mounting means such that one end is rigidly clamped to form a cantilever beam having an axis along the longitudinal dimension of the substrate; and the transducer set is disposed to propagate the acoustic surface wave along a path substantially corresponding to the axis of the cantilever beam.
Claim 9
Dependent Claim
108 words
the dual acoustic surface wave oscillator described in claim 1 employed as a temperature-compensated force-sensing device wherein: the substrate is mounted in mounting means to respond to a component of force applied normal thereto; and the second acoustic surface wave oscillator has an output signal frequency that varies inversely in response to the same component of force applied normal to the substrate when compared to the output signal frequency of the first acoustic surface wave oscillator; said output signal frequency of the second acoustic wave oscillator being substantially equal to the output signal frequency of the first oscillator when no component of force is applied to the substrate.
Claim 10
Dependent Claim
30 words
The temperature-compensated force-sensing device as described in claim 7 wherein the: resultant output signal has a frequency directly related to the magnitude of the force component applied to the substrate.
Claim 11
Dependent Claim
36 words
The temperature-compensated force-sensing device as described in claim 8 wherein the resultant output signal is a signal whose frequency is the algebraic difference between the frequencies of the output signals of the two acoustic wave oscillators.
Claim 12
Dependent Claim
37 words
The temperature-compensated force-sensing device of claim 7 wherein the difference frequency of the output signal of the mixing means is substantially zero with no component of force applied normal to a planar surface of the piezoelectric substrate.
Claim 13
Dependent Claim
74 words
The temperature-compensated force sensing device of claim 7 wherein: the output signal frequency of the first oscillator increases in response to compression stress of the first surface; the output signal frequency of the second oscillator decreases in response to tensile stress of the second surface; and the difference frequency output signal of the mixing means is directly related to the magnitude of the force applied normal to a planar surface of the piezoelectric substrate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |