Patent US3189929A successfully refreshed from Google Patents.
US4901006A
Expired / Lapsed
US
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Method and apparatus for AC signal comparison, calibration and measurement
Assignee: Electro Scientific Industries Inc
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Filing: 1989-06-29
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Granted: 1990-02-13
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Expires: 2009-06-29
Abstract
Abstract A method and apparatus for the comparision of AC signals by electrothermal means in which both signals are applied to an electrothermal converter, such as a thermocouple converter or a thermoresistive converter, and the temperature produced by the signals is converted to a difference signal. The DC component of the difference signal is used to maintain the electrothermal converter at a stable operating temperature. The AC component of the difference signal is used to indicate the difference between two signals when used as a comparator, to control the amplitude of a reference standard's output when used as a voltmeter or calibration standard, and also to control the amplitude of an oscillator when used as a calibration standard.
Inventors
- 👤 Archie J. Harrison, Jr.
- 👤 Fred L. Katzmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:51
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/22; G01R19/225
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
124 words
Electrothermal conversion apparatus for generating a DC voltage related to the RMS value of an AC signal comprising: (a) first elongate means for generating thermal energy in response to a first signal; (b) second elongate means for generating thermal energy in response to a second signal; (c) said first and second means being in physical contact with one another over a substantial portion of their lengths, separated only by thermally conductive electrical insulation over the substantial portion of their lengths for which they are in physical contact, and forming a heater assembly; and (d) a temperature responsive electrical sensing means in physical contact with said heater assembly, said temperature responsive means producing a temperature-indicating electrical signal representative of the temperature of said heater assembly.
Claim 2
Dependent Claim
124 words
Electrothermal conversion apparatus for generating a DC voltage related to the RMS value of an AC signal comprising: (a) first elongate means for generating thermal energy in response to a first signal; (b) second elongate means for generating thermal energy in response to a second signal; (c) said first and second means being in physical contact with one another over a substantial portion of their lengths, separated only by thermally conductive electrical insulation over the substantial portion of their lengths for which they are in physical contact, and forming a heater assembly; and (d) a temperature responsive electrical sensing means in physical contact with said heater assembly, said temperature responsive means producing a temperature-indicating electrical signal representative of the temperature of said heater assembly.
Claim 3
Dependent Claim
18 words
The apparatus of claim 1 wherein the first means and the second means each comprise a fine wire.
Claim 4
Dependent Claim
20 words
The apparatus of claim 2 wherein the temperature responsive means comprises a thermoresistive device connected to a source of current.
Claim 5
Dependent Claim
36 words
The apparatus of claim 3 wherein the thermoresistive device comprises a fine wire having a high thermal coefficient of resistivity which is in physical contact with the heater assembly over a substantial portion of its lengths.
Claim 6
Dependent Claim
22 words
The apparatus of claim 4 wherein the fine wires of the first and second means have a low thermal coefficient of resistivity.
Claim 7
Dependent Claim
14 words
The apparatus of claim 2 wherein the temperature responsive means comprises a thermocouple device.
Claim 8
Dependent Claim
26 words
The apparatus of claim 5 wherein the thermocouple device comprises a plurality of thermocouple junctions, each of which is in physical contact with the heater assembly.
Claim 9
Dependent Claim
29 words
The apparatus of claim 1 wherein the first and second elongate means are twisted together over the substantial portion of their lengths for which they are in physical contact.
Claim 10
Dependent Claim
111 words
Electrothermal conversion apparatus for generating a DC voltage related to the RMS value of an AC signal, comprising: (a) first means having a length for generating thermal energy in response to an AC signal; (b) second means having a length for generating thermal energy in response to a reference signal, the first and second means being twisted together over a portion of their lengths and being in thermal contact; and (c) a temperature responsive electrical sensing means in thermal contact with both the first and second means for producing thermal energy, the temperature responsive means producing a temperature-indicating electrical signal representative of the temperature produced by the first and second means.
Claim 11
Dependent Claim
111 words
Electrothermal conversion apparatus for generating a DC voltage related to the RMS value of an AC signal, comprising: (a) first means having a length for generating thermal energy in response to an AC signal; (b) second means having a length for generating thermal energy in response to a reference signal, the first and second means being twisted together over a portion of their lengths and being in thermal contact; and (c) a temperature responsive electrical sensing means in thermal contact with both the first and second means for producing thermal energy, the temperature responsive means producing a temperature-indicating electrical signal representative of the temperature produced by the first and second means.
Claim 12
Dependent Claim
25 words
The apparatus of claim 9 further comprising means for supplying a component of the temperature-indicating electrical signal to the second means as the reference signal.
Claim 13
Dependent Claim
26 words
The apparatus of claim 9 wherein the portion of the length of over which the first and second means are twisted together is a substantial portion.
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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) | 1993-02-12 | 1993-08-14 | 1994-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-12 | 1997-08-14 | 1998-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-12 | 2001-08-14 | 2002-02-13 | $7700.00 | Window Closed / Lapsed |