US3562641A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impedance-measuring transformer bridge with automatic digital balancing circuit
Assignee: General Radio Co
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Filing: 1968-11-25
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Granted: 1971-02-09
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Expires: 1988-11-25
Abstract
Abstract The present invention relates to automatic electrical bridgebalancing circuits and, more particularly, to bridge circuits, preferably of the transformer bridge type, employing alternatingcurrent digital servo controls for effecting rapid balancing of unknown impedance elements, such as capacitances.
Inventors
- 👤 Robert G Fulks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 03:34
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R17/00; G01R17/10; G01R17/105
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
147 words
An automatic impedance bridge having, in combination, a bridge circuit provided with an input and an output, an AC source connected across the input, said bridge circuit comprising unknown and standard impedance bridge arms being of the type in which an unknown impedance is to be measured against a known impedance standard and variations of AC voltage ratios in the bridge arms respectively containing the unknown and standard impedances are used to effect a bridge balance, means connected across the output for detecting the direction of bridge unbalance, logic circuit means connected to and responsive to the detecting means for producing a control signal representing the direction of unbalance, and digital means connected to the logic circuit means and responsive to the control signal for successively changing the voltage ratio of the said standard and unknown impedance bridge arms to reduce successively the degree of bridge unbalance.
Claim 2
Dependent Claim
147 words
An automatic impedance bridge having, in combination, a bridge circuit provided with an input and an output, an AC source connected across the input, said bridge circuit comprising unknown and standard impedance bridge arms being of the type in which an unknown impedance is to be measured against a known impedance standard and variations of AC voltage ratios in the bridge arms respectively containing the unknown and standard impedances are used to effect a bridge balance, means connected across the output for detecting the direction of bridge unbalance, logic circuit means connected to and responsive to the detecting means for producing a control signal representing the direction of unbalance, and digital means connected to the logic circuit means and responsive to the control signal for successively changing the voltage ratio of the said standard and unknown impedance bridge arms to reduce successively the degree of bridge unbalance.
Claim 3
Dependent Claim
24 words
Bridge apparatus as claimed in Claim 1 and in which the said digital means comprises switching means for successively changing the said voltage ratio.
Claim 4
Dependent Claim
25 words
Bridge apparatus as claimed in claim 2 and in which the said switching means successively varies the current passed through the said standard impedance arm.
Claim 5
Dependent Claim
25 words
Bridge apparatus as claimed in claim 2 and in which the said switching means successively varies the voltage applied to the said standard impedance arm.
Claim 6
Dependent Claim
28 words
Bridge apparatus as claimed in claim 2 and in which the said switching means successively varies the value of standard impedance connected in the said standard impedance arm.
Claim 7
Dependent Claim
29 words
Bridge apparatus as claimed in claim 2 and in which the said bridge is of the ratio-transformer type, portions of the transformer serving as other arms of the bridge.
Claim 8
Dependent Claim
38 words
Bridge apparatus as claimed in claim 6 and in which the said switching means successively varies the connection of the said standard impedance arm to different points along one of the said other transformer arms of the bridge.
Claim 9
Dependent Claim
28 words
Bridge apparatus as claimed in claim 7 and in which the said standard impedance arm comprises the said switching means and a plurality of similar standard impedance elements.
Claim 10
Dependent Claim
30 words
Bridge apparatus as claimed in claim 6 and in which the said standard impedance arm comprises the said switching means and a plurality of successively different-valued impedance elements selected thereby.
Claim 11
Dependent Claim
27 words
Bridge apparatus as claimed in claim 2 and in which the said digital means further comprises reversible counter means and the detecting means comprises a phase detector.
Claim 12
Dependent Claim
52 words
Bridge apparatus as claimed in claim 10 and in which the Said switching means and standard impedance comprise a digital-to-analogue converter means for producing either a current through the standard impedance or a voltage in the said standard impedance arm that is the analogue of the count in the reversible counter means.
Claim 13
Dependent Claim
48 words
Bridge apparatus as claimed in claim 10 and in which the said logic circuit means comprises control means responsive to the said phase detector for providing a direction-of-count signal to the reversible counter means and for enabling pulses to be applied to the reversible counter means during unbalance.
Claim 14
Dependent Claim
104 words
Bridge apparatus as claimed in claim 12 in which said reversible counter means has a plurality of digit stages and in which the said control means comprises the combination of voltage comparator means for comparing the output of the detecting means with a reference, a plurality of gating means connected between the voltage comparator means and the digit stages, respectively of the reversible counter means, clock pulse-producing means connected to the gating means for applying clock pulses to the digit stages of the reversible counter means, and counter means connected to the output of said voltage comparator means for opening said gating means sequentially.
Claim 15
Dependent Claim
25 words
Bridge apparatus as claimed in claim 10 and in which means is provided for extracting a binary coded decimal output from the reversible counter means.
Claim 16
Dependent Claim
32 words
Bridge apparatus as claimed in claim 10 and in which digital indicating means is connected to the reversible counter means for indicating the value of the said unknown impedance at bridge balance.
Claim 17
Dependent Claim
18 words
Bridge apparatus as claimed in claim 2 and in which the said unknown and standard impedances comprise capacitance.
Claim 18
Dependent Claim
18 words
Bridge apparatus as claimed in claim 2 and in which the said unknown and standard impedances comprise conductance.
Claim 19
Dependent Claim
87 words
Bridge apparatus as claimed in claim 2, said unknown and standard impedance bridge arms including conductance and reactance provided with means for connecting the conductance and reactance of each arm in shunt, further means for detecting bridge unbalance of phase in quadrature relation with that of the first-named detecting means, and additional logic circuit and digital means connected with the further detecting means successively to change the voltage ratio of the said unknown and standard conductance bridge arms to reduce successively the degree of phase-quadrature bridge unbalance.
Claim 20
Dependent Claim
19 words
Bridge apparatus as claimed in claim 18 and in which the said additional digital means comprises reversible counter means.
Claim 21
Dependent Claim
49 words
Bridge apparatus as claimed in claim 19 and in which the said additional logic circuit means comprises control means responsive to the further detecting means for providing direction-of-count signals to the said reversible counter means and for enabling pulses to be applied to the reversible counter means during unbalance.
Claim 22
Dependent Claim
105 words
Bridge apparatus as claimed in claim 20 in which said reversible counter means has a plurality of digit stages and in which the said control means comprises the combination of voltage comparator means for comparing the output of the further detecting means with a reference, a plurality of gating means connected between the voltage comparator means and the digit stages, respectively, of the reversible counter means, clock pulse-producing means connected to the gating means for applying clock pulses to the digit stages of the reversible counter means, and counter means connected to the output of said voltage comparator means for opening said gating means sequentially.
Claim 23
Dependent Claim
28 words
Bridge apparatus as claimed in claim 18 and in which the bridge is of the ratio-transformer type, portions of the transformer serving as other arms of the bridge.
Claim 24
Dependent Claim
37 words
Bridge apparatus as claimed in claim 22 and in which the said switching means successively varies the connection of the said standard impedance arm to different points along one of said other transformer arms of the bridge.
Claim 25
Dependent Claim
28 words
Bridge apparatus as claimed in claim 23 aNd in which the said standard impedance arm comprises the said switching means and a plurality of similar standard impedance elements.
Claim 26
Dependent Claim
30 words
Bridge apparatus as claimed in claim 22 and in which the said standard impedance arm comprises the said switching means and a plurality of successively different-valued impedance elements selected thereby.
Claim 27
Dependent Claim
67 words
Bridge apparatus as claimed in claim 18 and in which the switching means of the said second digital means is connected to cause either the successive variation of connection of the said standard conductance arm to different points along one of the said other transformer arms of the bridge or selection in the said standard conductance arm of different conductance elements of a plurality of conductance elements.
Claim 28
Dependent Claim
38 words
Bridge apparatus as claimed in claim 18 and in which selective means is provided alternately to connect the said standard conductance arm in shunt with different portions of the said standard impedance arm to enable dissipation factor indications.
Claim 29
Dependent Claim
54 words
Bridge apparatus as claimed in claim 13 and in which the reversible counter means counts past balance causing the voltage comparator means to enable the said gating means to permit the feeding of further pulses from said clock-pulse producing means in order to apply successive significant digits of count to the reversible counter means.
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) | 1974-02-08 | 1974-08-10 | 1975-02-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-08 | 1978-08-10 | 1979-02-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-08 | 1982-08-10 | 1983-02-09 | $7700.00 | Window Closed / Lapsed |