US4205556A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuitry for strain sensitive apparatus
Assignee: Boeing North American Inc
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Filing: 1979-02-12
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Granted: 1980-06-03
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Expires: 1999-02-12
Abstract
Abstract Strain gauge apparatus comprises two strain sensitive piezoresistors R r1 and R t1 , two op-amps, three predetermined value resistances, R a , R b , and R c , and voltage source supplying V dc . Said elements are connected to produce an output signal of the form V dc (R c /R a l ) (R r1 / R t1 -R a /R b ).
Inventors
- 👤 Wesley G. Runyan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 18:45
CPC Classifications
G; G01; G01L; G01L1/00; G01L1/20; G01L1/22; G01L1/225; G01L1/2262; G01L9/00; G01L9/0041; G01L9/0051; G01L9/0052; G01L9/0054; G01L9/02; G01L9/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
290 words
Strain gauge apparatus comprising: (a) first and second resistance means R w and R x connected together at one end to form a node N a , (b) first and second strain sensitive resistance means R y and R z which vary in opposite directions with variation in strain, R y and R z being connected together at one end to form a node N b , the unused ends of R w and R y being connected together to form a node N c , and the unused ends of R x and R z being connected together to form a node N d , (c) supply means connected for establishing a predetermined voltage V s at N a , (d) first operational amplifier (op-amp) means having inverting and non-inverting input means and output means, a predetermined one of said first op-amp input means being connected to a predetermined reference potential V R , and the other of said first op-amp input means being connected to N c , (e) means for providing to N b a signal indicative of said first op-amp output, (f) second operational amplifier (op-amp) means having inverting and non-inverting input means and an output means, a predetermined one of said second op-amp input means being connected to N d and the other of said second op-amp input means being connected to a predetermined one of (i) N c or (ii) the predetermined reference potential V R , and (g) feedback means connected to the output means of said second op-amp for feeding back to a predetermined one of N c or N d a signal which assures that the potential at N d remains substantially independent of variations in said strain sensitive resistance means.
Claim 2
Dependent Claim
290 words
Strain gauge apparatus comprising: (a) first and second resistance means R w and R x connected together at one end to form a node N a , (b) first and second strain sensitive resistance means R y and R z which vary in opposite directions with variation in strain, R y and R z being connected together at one end to form a node N b , the unused ends of R w and R y being connected together to form a node N c , and the unused ends of R x and R z being connected together to form a node N d , (c) supply means connected for establishing a predetermined voltage V s at N a , (d) first operational amplifier (op-amp) means having inverting and non-inverting input means and output means, a predetermined one of said first op-amp input means being connected to a predetermined reference potential V R , and the other of said first op-amp input means being connected to N c , (e) means for providing to N b a signal indicative of said first op-amp output, (f) second operational amplifier (op-amp) means having inverting and non-inverting input means and an output means, a predetermined one of said second op-amp input means being connected to N d and the other of said second op-amp input means being connected to a predetermined one of (i) N c or (ii) the predetermined reference potential V R , and (g) feedback means connected to the output means of said second op-amp for feeding back to a predetermined one of N c or N d a signal which assures that the potential at N d remains substantially independent of variations in said strain sensitive resistance means.
Claim 3
Dependent Claim
44 words
Apparatus as defined in claim 1 wherein said first and second strain sensitive resistance means comprise semiconductor material of either the p or n-type carried by diaphragm means comprising semiconductor material of the other type, said diaphragm means being connected to V R .
Claim 4
Dependent Claim
38 words
Apparatus as defined in claim 2 wherein the polarity of V s relative to V R is appropriate to avoid a forward current flow through the p-n junction between said diaphragm means and said strain sensitive resistance means.
Claim 5
Dependent Claim
31 words
Apparatus as defined in claim 2 wherein said strain sensitive resistance means comprise p-type material, said diaphragm means comprises n-type material, and V s is more positive than V R .
Claim 6
Dependent Claim
16 words
Apparatus as defined in claim 1 wherein said feedback means comprises resistance means of predetermined value.
Claim 7
Dependent Claim
35 words
Apparatus as defined in claim 1 wherein said means for providing to N b a signal indicative of said first op-amp output comprises means for connecting said first op-amp output means to N b .
References Cited (Backward Citations)
US3049685A
Cited
US3457493A
Cited
US3456226A
Cited
US3572109A
Cited
US3641812A
Cited
US3836796A
Cited
US3841150A
Cited
US3956927A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-06-03 | 1983-12-03 | 1984-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-06-03 | 1987-12-03 | 1988-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-06-03 | 1991-12-03 | 1992-06-03 | $7700.00 | Window Closed / Lapsed |