Patent US3742347A successfully refreshed from Google Patents.
US3742347A
Expired / Lapsed
US
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Shaft movement differential pressure measuring apparatus embodying capacitive transducers
Assignee: United Kingdom Atomic Energy Authority
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Filing: 1971-08-25
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Granted: 1973-06-26
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Expires: 1991-08-25
Abstract
Abstract Measuring apparatus including a capacitive transducer which comprises members between which a first capacitance increases and a second capacitance simultaneously decreases in accordance with the magnitude of the physical quantity being measured. The first and second capacitances are connected as two arms of a four-arm bridge having as each of the two other arms a charge amplifier. Means are provided for applying an AC carrier waveform to the junction of the first and second capacitances and for demodulating the differential output of the two charge amplifiers to give an output representative of the magnitude of the physical quantity.
Inventors
- 👤 H Walton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:34
CPC Classifications
G; G01; G01L; G01L13/00; G01L13/02; G01L13/025; G01L1/00; G01L1/14; G01L1/142; G01L1/144; G01L9/00; G01L9/0041; G01L9/0072; G01L9/12; G01L9/125
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
138 words
Measuring apparatus comprising a capacitive transducer comprising members providing a first capacitor and a second capacitor, the capacitance of at least one of said capacitors being variable in accordance with the magnitude of a physical quantity being measured; a four arm bridge; means for connecting said capacitor as two arms of said four arm bridge; two charge amplifiers; means for connecting said charge amplifiers so that said amplifiers and the inputs thereto form the other two arms of said four arm bridge; means for applying an A.C. carrier waveform across the junction of said capacitors and the junction of the inputs of said amplifiers; means for deriving a differential output signal from the outputs of said charge amplifiers; and means for demodulating said differential output signal to produce an output representative of the magnitude of said physical quantity.
Claim 2
Dependent Claim
138 words
Measuring apparatus comprising a capacitive transducer comprising members providing a first capacitor and a second capacitor, the capacitance of at least one of said capacitors being variable in accordance with the magnitude of a physical quantity being measured; a four arm bridge; means for connecting said capacitor as two arms of said four arm bridge; two charge amplifiers; means for connecting said charge amplifiers so that said amplifiers and the inputs thereto form the other two arms of said four arm bridge; means for applying an A.C. carrier waveform across the junction of said capacitors and the junction of the inputs of said amplifiers; means for deriving a differential output signal from the outputs of said charge amplifiers; and means for demodulating said differential output signal to produce an output representative of the magnitude of said physical quantity.
Claim 3
Dependent Claim
65 words
Apparatus as claimed in claim 1 wherein said transducer which comprises the capacitor arms of said bridge is remotely located relative to the charge amplifiers and said means for applying said carrier waveform, said apparatus further comprising ground-sheathed cables for establishing connections between said transducer on the one hand and said charge amplifiers and said means for applying said carrier waveform on the other hand.
Claim 4
Dependent Claim
85 words
Apparatus as claimed in claim 1 wherein said means for applying said carrier waveform includes a thermocouple cable, said apparatus further comprising a thermocouple for registering the temperature at said transducer and generating an e.m.f. in accordance therewith, a temperature compensating multiplier, connected to accept said output representative of the magnitude of said physical quantity, for modifying said output to compensate for the effects of temperature changes at the transducer, and means for utilizing the e.m.f. of said thermocouple to control said temperature compensating multiplier.
Claim 5
Dependent Claim
29 words
Apparatus as claimed in claim 1 wherein said members include a first member located between two further members and arranged to be displaced relative to said two further members.
Claim 6
Dependent Claim
30 words
Apparatus as claimed in claim 4, wherein the first said member comprises a deflectable cantilever beam and said two further members are rigidly connected to the casing of the transducer.
Claim 7
Dependent Claim
34 words
Apparatus as claimed in claim 5, for measuring a pressure differential, wherein the transducer comprises a diaphragm means linked to each side of said cantilever beam by push rod means for deflecting said beam.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |