US3577075A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital servo indicator
Assignee: Gilmore Industries Inc
•
Filing: 1968-11-14
•
Granted: 1971-05-04
•
Expires: 1988-11-14
Abstract
Abstract An automatic, null-balance potentiometric device having a digital readout in which the rate of balance is proportional to the magnitude of the error and balance is approached asymptotically on an exponential curve, such device providing improved damping characteristics and noise reduction whereby accurate resolution to a hundredth of a microvolt is obtained.
Inventors
- 👤 Algirdas J Krygeris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 01:19
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/48; H03M1/60
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
166 words
A digital voltmeter for measuring an unknown voltage produced by the unbalance of a bridge comprising: first digital-to-analog converter means for producing a known variable voltage, said known voltage being connected in opposition to said unknown voltage so that the difference therebetween constitutes an error signal, a voltage-to-frequency converter for converting said error signal to a series of pulses having a repetition rate proportional to the magnitude of said error signal, the constant of proportionality remaining the same throughout the measurement, a bidirectional counter controlling said first digital-to-analog converter means and adapted to be incremented or decremented by said pulses, means responsive to the polarity of said error signal for enabling said counter to be incremented by said pulses for one polarity and decremented by said pulses for the oppositE polarity, and second digital-to-analog converter means connected to said unknown voltage and to said first digital-to-analog converter means for cancelling the net flow of measurement circuit current between said first digital-to-analog converter means and said bridge.
Claim 2
Dependent Claim
166 words
A digital voltmeter for measuring an unknown voltage produced by the unbalance of a bridge comprising: first digital-to-analog converter means for producing a known variable voltage, said known voltage being connected in opposition to said unknown voltage so that the difference therebetween constitutes an error signal, a voltage-to-frequency converter for converting said error signal to a series of pulses having a repetition rate proportional to the magnitude of said error signal, the constant of proportionality remaining the same throughout the measurement, a bidirectional counter controlling said first digital-to-analog converter means and adapted to be incremented or decremented by said pulses, means responsive to the polarity of said error signal for enabling said counter to be incremented by said pulses for one polarity and decremented by said pulses for the oppositE polarity, and second digital-to-analog converter means connected to said unknown voltage and to said first digital-to-analog converter means for cancelling the net flow of measurement circuit current between said first digital-to-analog converter means and said bridge.
Claim 3
Dependent Claim
28 words
The digital voltmeter of claim 1 further comprising rheostat means coupled to an output terminal of said bridge for zeroing said digital voltmeter when said bridge is balanced.
Claim 4
Dependent Claim
42 words
The digital volt meter of claim 2 further comprising second rheostat means coupled to an output terminal of said bridge and to said rheostat means for cancelling the net flow of measurement circuit current between said zeroing rheostat means and said bridge.
Claim 5
Dependent Claim
98 words
The digital voltmeter of claim 3 wherein said first digital-to-analog converter means and said second digital-to-analog converter means are connected to a first output terminal of said bridge, said zeroing rheostat means and said second rheostat means are connected to a second output terminal of said bridge, and the impedance presented to said first output terminal of said bridge by the combination of said digital-to-analog converter and said second digital-to-analog converter is equal to the impedance presented to said second output terminal of said bridge by the combination of said zeroing rheostat means and said second rheostat means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-05-03 | 1974-11-02 | 1975-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-03 | 1978-11-02 | 1979-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-03 | 1982-11-02 | 1983-05-04 | $7700.00 | Window Closed / Lapsed |