US4286459A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Force sensor
Assignee: Johnson and Johnson
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Filing: 1979-10-30
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Granted: 1981-09-01
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Expires: 1999-10-30
Abstract
Abstract Positive feedback is utilized with a flexible piezoelectric strip that is stretched in tension to cause the strip to oscillate at a frequency which is determined by the magnitude of the force stretching the flexible strip. Since the oscillation frequency can readily be measured, the strip is utilized as a device for measuring tension.
Inventors
- 👤 William S. N. Trimmer
- 👤 Mark R. Laser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 00:18
CPC Classifications
G; G01; G01L; G01L1/00; G01L1/16; G01L1/162; Y; Y10; Y10S; Y10S73/00; Y10S73/01; Y10S73/04
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
75 words
A force measuring device comprising: a strip of flexible piezoelectric material; at least first and second electrically conductive coatings on said strip; a mass on said strip intermediate the ends thereof; positive feedback means coupled between said conductive coatings; and means to enable a force to be applied to at least one end of said strip thereby causing said strip and said mass to oscillate at a frequency determined by the magnitude of said force.
Claim 2
Dependent Claim
75 words
A force measuring device comprising: a strip of flexible piezoelectric material; at least first and second electrically conductive coatings on said strip; a mass on said strip intermediate the ends thereof; positive feedback means coupled between said conductive coatings; and means to enable a force to be applied to at least one end of said strip thereby causing said strip and said mass to oscillate at a frequency determined by the magnitude of said force.
Claim 3
Dependent Claim
19 words
The force measuring device according to claim 1 wherein said force causes said strip to be stretched in tension.
Claim 4
Dependent Claim
39 words
The force measuring device according to claim 1 wherein a charge density is induced across the surfaces of the strip when it is stretched and said strip changes its length when an electrical voltage is applied across its surfaces.
Claim 5
Dependent Claim
15 words
The force measuring device according to claim 1 wherein said flexible strip is polyvinylidene fluoride.
Claim 6
Dependent Claim
16 words
The force measuring device according to claim 1 wherein said positive feedback loop includes an amplifier.
Claim 7
Dependent Claim
32 words
The force measuring device according to claim 5 wherein said amplifier is biased to be overdriven to produce electrical pulses the frequency of which is determined by the magnitude of said force.
Claim 8
Dependent Claim
162 words
A force measuring device comprising: a first strip of flexible piezoelectric material; an electrically conductive coating on opposite sides of said first strip; a second strip of flexible piezoelectric material; an electrically conductive coating on opposite sides of said second strip; said conductive coating on one side of said first strip being electrically coupled to the conductive coating on one side of said second strip adjacent to each end of said first and second strips; said electrically coupled coatings on said first and second strips connected to a reference potential; positive electrical feedback means coupled between the other conductive coating on said first strip and the other conductive coating on said second strip; a mass located between said first and second strips intermediate the ends thereof; and means to enable a force to be applied to at least one end of said strip(s) thereby causing said strips and said mass to oscillate at a frequency determined by the magnitude of said force.
Claim 9
Dependent Claim
162 words
A force measuring device comprising: a first strip of flexible piezoelectric material; an electrically conductive coating on opposite sides of said first strip; a second strip of flexible piezoelectric material; an electrically conductive coating on opposite sides of said second strip; said conductive coating on one side of said first strip being electrically coupled to the conductive coating on one side of said second strip adjacent to each end of said first and second strips; said electrically coupled coatings on said first and second strips connected to a reference potential; positive electrical feedback means coupled between the other conductive coating on said first strip and the other conductive coating on said second strip; a mass located between said first and second strips intermediate the ends thereof; and means to enable a force to be applied to at least one end of said strip(s) thereby causing said strips and said mass to oscillate at a frequency determined by the magnitude of said force.
Claim 10
Dependent Claim
17 words
The force measuring device according to claim 7 wherein said first and second strip is polyvinylidene fluoride.
Claim 11
Dependent Claim
22 words
The force measuring device according to claim 7 wherein said force causes said first and second strips to be stretched in tension.
Claim 12
Dependent Claim
41 words
The force measuring device according to claim 9 wherein a charge density is induced across the coated surfaces of said strips when they are stretched and said strips change their length when an electrical voltage is applied across their coated surfaces.
Claim 13
Dependent Claim
16 words
The force measuring device according to claim 10 wherein said positive feedback loop includes an amplifier.
Claim 14
Dependent Claim
30 words
The force measuring device according to claim 11 wherein said amplifier is biased to be overdriven to produce electrical pulses having a frequency determined by the magnitude of said force.
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) | 1984-08-31 | 1985-03-02 | 1985-09-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-31 | 1989-03-02 | 1989-09-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-31 | 1993-03-02 | 1993-09-01 | $7700.00 | Window Closed / Lapsed |