Patent US4954776A successfully refreshed from Google Patents.
US4954776A
Expired / Lapsed
US
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Linear displacement transducers utilizing voltage component in phase with current that varies linearly with core displacement
Assignee: Penny and Giles International PLC
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Filing: 1989-02-21
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Granted: 1990-09-04
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Expires: 2009-02-21
Abstract
Abstract A linear displacement transducer comprises a winding, a magnetic core which is linearly displaceable relatively to the winding, and a source for energizing the winding with a constant RMS alternating current at a frequency sufficiently high for the resistive losses in the magnetic core to cause the voltage across the winding to vary substantially linearly relative to the linear displacement of the magnetic core. The frequency may, for example, be in the range 10 to 20 kHz, and a temperature sensing winding may be associated with the winding to enable the output from the transducer to be compensated for temperature changes, or the winding may be used in time-division multiplex for this purpose.
Inventors
- 👤 Stephen Husher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:23
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/20; G01D5/2006; G01D5/2013; G01D3/00; G01D3/028; G01D3/036; G01D3/0365
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
68 words
A linear displacement transducer comprising: a winding; a magnetic core which is linearly displaceable relative to said winding; and means for energizing said winding with a constant RMS alternating current of a fixed frequency sufficiently high for the losses in said magnetic core to cause the voltage across said winding in phase with the current to vary substantially linearly relative to the linear displacement of said magnetic core.
Claim 2
Dependent Claim
68 words
A linear displacement transducer comprising: a winding; a magnetic core which is linearly displaceable relative to said winding; and means for energizing said winding with a constant RMS alternating current of a fixed frequency sufficiently high for the losses in said magnetic core to cause the voltage across said winding in phase with the current to vary substantially linearly relative to the linear displacement of said magnetic core.
Claim 3
Dependent Claim
21 words
A transducer according to claim 1 wherein said winding is a single layer helical winding wound on a straight tubular former.
Claim 4
Dependent Claim
26 words
A transducer according to claim 2 wherein said magnetic core is a straight cylindrical metal rod which penetrates axially into the interior of said tubular former.
Claim 5
Dependent Claim
22 words
A transducer according to claim 1 wherein the frequency of said alternating current is fixed within the range 10 to 20 kHz.
Claim 6
Dependent Claim
35 words
A transducer according to claim 1 wherein a temperature sensing winding is disposed adjacent to said winding for the purpose of effecting temperature control of an output voltage derived from said voltage across said winding.
Claim 7
Dependent Claim
37 words
A transducer according to claim 1 wherein said winding is used in time-division multiplex for deriving said voltage across said winding, and for effecting temperature control of an output voltage derived from said voltage across said winding.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-09-03 | 1994-03-05 | 1994-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-03 | 1998-03-05 | 1998-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-03 | 2002-03-05 | 2002-09-04 | $7700.00 | Window Closed / Lapsed |