US3889255A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital calibration system for an electronic instrument
Assignee: Corning Glass Works
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Filing: 1974-03-22
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Granted: 1975-06-10
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Expires: 1994-03-22
Abstract
Abstract In a pH measuring instrument, automatic calibration (sloping) is performed by placing the pH electrode in a standard solution, dialing the pH of this standard solution into a decade thumb wheel switch, and depressing the slope switch. The measurement voltage from the electrode is converted to a binary coded digital signal. This signal and the digital signal from the thumb wheel switch are applied to a binary adder which produces a multiple bit output representing the difference. Clock pulses are supplied to a reversible digital counter which counts in a direction specified by the most significant bit of the binary adder output. The count in the reversible counter, representing the error, is converted to an analog signal which is used to control the reference voltage in a ratio system to produce a calibrated reading. The supply of clock pulses to the counter is automatically stopped when the error is zero.
Inventors
- 👤 Aage Pettersen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 00:28
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/416; G01N27/4163; G01N27/4165; G12; G12B; G12B13/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
201 words
An automatic calibration system for an electronic instrument which produces a measurement votlage and which produces a calibrating voltage in response to a standard during a calibration mode of operation comprising: means for converting said calibrating voltage to a binary coded digital signal, manually settable switch means producing a binary coded digital signal representing the magnitude of said standard, a binary adder, the binary coded digital signals from said means for converting and from said manually settable switch means being applied to said binary adder, said binary adder producing a multiple bit digital output representing the difference between the applied digital signals, a digital counter, a source of clock pulses, gating means, said multiple bit digital output being connected to said gating means, said clock pulses being applied through said gating means to said counter, said gating means being connected to stop the application of pulses to said counter when said difference is zero so that said counter counts a number of pulses related to said difference, and a digital-to-analog converter responsive to the outputs of said counter to produce an analog output voltage related to said difference, said analog output voltage controlling said instrument to produce a calibrated measurement voltage.
Claim 2
Dependent Claim
201 words
An automatic calibration system for an electronic instrument which produces a measurement votlage and which produces a calibrating voltage in response to a standard during a calibration mode of operation comprising: means for converting said calibrating voltage to a binary coded digital signal, manually settable switch means producing a binary coded digital signal representing the magnitude of said standard, a binary adder, the binary coded digital signals from said means for converting and from said manually settable switch means being applied to said binary adder, said binary adder producing a multiple bit digital output representing the difference between the applied digital signals, a digital counter, a source of clock pulses, gating means, said multiple bit digital output being connected to said gating means, said clock pulses being applied through said gating means to said counter, said gating means being connected to stop the application of pulses to said counter when said difference is zero so that said counter counts a number of pulses related to said difference, and a digital-to-analog converter responsive to the outputs of said counter to produce an analog output voltage related to said difference, said analog output voltage controlling said instrument to produce a calibrated measurement voltage.
Claim 3
Dependent Claim
43 words
The system recited in claim 1 wherein said digital counter is reversible, the carry output of said binary adder being connected to said gating means to control the application of clock pulses to the countup or countdown input of said reversible digital counter.
Claim 4
Dependent Claim
40 words
The system recited in claim 1 wherein said electronic instrument is in a ratio system for ph measurement and wherein said analog output voltage is applied to control the reference voltage in the ratio system to produce a calibration reading.
Claim 5
Dependent Claim
111 words
The system recited in claim 1 wherein said source of clock pulses includes: an oscillator, binary counters, the output of said oscillator being applied to said binary counters so that said binary counters produce outputs of different frequency clock pulses, a frequency gate, said multiple bit output from said binary adder being applied to said frequency gate, said different frequency clock pulses from said binary counters being applied to said frequency gate so that different bit outputs of said binary adder enable different frequency clock pulses to pass through said frequency gate whereby the frequency of the pulses applied to said reversible counter is proportional to the magnitude of said difference.
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) | 1978-06-09 | 1978-12-09 | 1979-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-09 | 1982-12-09 | 1983-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-09 | 1986-12-09 | 1987-06-10 | $7700.00 | Window Closed / Lapsed |