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US4079272A
Expired / Lapsed
US
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Optically isolated interface circuits
Assignee: Charles Stark Draper Laboratory Inc
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Filing: 1976-03-31
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Granted: 1978-03-14
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Expires: 1996-03-31
Abstract
Abstract Circuitry for providing electrical isolation between an input signal source and other circuitry which utilizes such input signal. The isolation circuitry uses an optical coupling means comprising a light-emitting diode circuit and a photo-responsive element, the input signal being supplied by a bridge circuit which provides a unidirectional voltage from the input signal which is then applied to a normalizing, or limiting, circuit which converts the unidirectional voltage to a substantially constant value which is supplied to the light-emitting diode circuit. The circuit is responsive to an input signal which can be an AC signal or a DC signal of either polarity, such circuit having a high degree of noise survivability even in the presence of transient noise signals such as "showering arcs" having extremely high amplitudes.
Inventors
- 👤 John R. Howatt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:12
CPC Classifications
H; H03; H03K; H03K5/00; H03K5/003; H03K17/00; H03K17/51; H03K17/78; H03K17/795
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
145 words
A circuit responsive to an input signal for providing an output signal which is electrically isolated therefrom, said circuit comprising means responsive to said input signal for providing a unidirectional signal having a predetermined polarity; a plurality of series-connected and forward-biased diode means responsive to said unidirectional signal for providing a d-c signal having said predetermined polarity and having a substantially constant amplitude; and coupling means responsive to said substantially constant amplitude d-c signal for providing a coupled output signal which is representative thereof and is electrically isolated therefrom, the number of said series-connected and forward-biased diode means being selected so as to provide a voltage drop thereacross which is greater than the voltage drop across said coupling means and a substantially constant current through said coupling means, said diode means further preventing the presence of substantially large voltage transient signals at said coupling means.
Claim 2
Dependent Claim
145 words
A circuit responsive to an input signal for providing an output signal which is electrically isolated therefrom, said circuit comprising means responsive to said input signal for providing a unidirectional signal having a predetermined polarity; a plurality of series-connected and forward-biased diode means responsive to said unidirectional signal for providing a d-c signal having said predetermined polarity and having a substantially constant amplitude; and coupling means responsive to said substantially constant amplitude d-c signal for providing a coupled output signal which is representative thereof and is electrically isolated therefrom, the number of said series-connected and forward-biased diode means being selected so as to provide a voltage drop thereacross which is greater than the voltage drop across said coupling means and a substantially constant current through said coupling means, said diode means further preventing the presence of substantially large voltage transient signals at said coupling means.
Claim 3
Dependent Claim
16 words
A circuit in accordance with claim 1 wherein said coupling means is an optical coupling means.
Claim 4
Dependent Claim
17 words
A circuit in accordance with claim 2 wherein said unidirectional signal providing means comprises a bridge circuit.
Claim 5
Dependent Claim
20 words
A circuit in accordance with claim 3 wherein said diode means are connected in parallel with said optical coupling means.
Claim 6
Dependent Claim
42 words
A circuit in accordance with claim 2 wherein said optical coupling means includes a light emitting diode responsive to said d-c signal for producing a light signal and a photo detector means responsive to said light signal for providing an electrical signal.
Claim 7
Dependent Claim
20 words
A circuit in accordance with claim 1 and further including capacitance means connected in parallel with said series-connected diode means.
Claim 8
Dependent Claim
22 words
A circuit in accordance with claim 1 and further including means responsive to said coupled output signal for shaping the waveform thereof.
Claim 9
Dependent Claim
17 words
A circuit in accordance with claim 7 wherein said waveform shaping means comprises a Schmitt trigger circuit.
Claim 10
Dependent Claim
32 words
A circuit in accordance with claim 8 wherein said Schmitt trigger circuit is adapted to be responsive to a strobe signal for disabling said Schmitt trigger when said strobe signal is present.
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) | 1981-03-13 | 1981-09-12 | 1982-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-03-13 | 1985-09-12 | 1986-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-03-13 | 1989-09-12 | 1990-03-14 | $7700.00 | Window Closed / Lapsed |