US3894175A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Line control unit for teleprinters
Assignee: Olivetti SpA
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Filing: 1973-11-16
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Granted: 1975-07-08
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Expires: 1993-11-16
Abstract
Abstract A control unit for connecting a teleprinter to a transmission line wherein the electrical insulation between the teleprinter and the line is achieved by opto-electronic circuits. These circuits comprise a photoemissive diode connected to the control unit of the teleprinter and a photosensitive transistor, connected to the line, and optically coupled to the diode for transmitting electrical signals coming from the control unit to the line and for electrically insulating the control unit from the line at the same time.
Inventors
- 👤 Giovanni Zaffignani
- 👤 Oscar Mannocchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:22
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/20; H04L25/26
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
239 words
A line control unit for connecting a teleprinter to a transmission line comprising: a switching circuit for defining different operation modes of the teleprinter by means of a pair of command signals, a first combination of said pair of signals (L 0, TR 1) indicating a local operation mode, a second combination (L 1, TR 0) of said pair indicating a request for transmission mode, an actuating circuit for modulating the amplitude of the electrical current flowing on said line from a first value to a second value according to the mode indicated by said couple of signals, and a pair of optoelectronic coupling circuits for supplying said actuating circuit with a pair of control signals associated with said pair of command signals and for providing an electrical isolation between said switching circuit and said actuating circuit, wherein said actuating circuit comprises: a first electronic switch disposed in series with said line through a resistor and having a control input via one of said pair of optoelectronic coupling circuits responsive to one control signal of said pair of signals for modulating the amplitude of said line current to said first value, a second electronic switch disposed in series with said line and in parallel with said first electronic switch and responsive via the other of said optoelectronic coupling circuits to the other control signal of said pair for modulating the amplitude of said line current to said second value.
Claim 2
Dependent Claim
239 words
A line control unit for connecting a teleprinter to a transmission line comprising: a switching circuit for defining different operation modes of the teleprinter by means of a pair of command signals, a first combination of said pair of signals (L 0, TR 1) indicating a local operation mode, a second combination (L 1, TR 0) of said pair indicating a request for transmission mode, an actuating circuit for modulating the amplitude of the electrical current flowing on said line from a first value to a second value according to the mode indicated by said couple of signals, and a pair of optoelectronic coupling circuits for supplying said actuating circuit with a pair of control signals associated with said pair of command signals and for providing an electrical isolation between said switching circuit and said actuating circuit, wherein said actuating circuit comprises: a first electronic switch disposed in series with said line through a resistor and having a control input via one of said pair of optoelectronic coupling circuits responsive to one control signal of said pair of signals for modulating the amplitude of said line current to said first value, a second electronic switch disposed in series with said line and in parallel with said first electronic switch and responsive via the other of said optoelectronic coupling circuits to the other control signal of said pair for modulating the amplitude of said line current to said second value.
Claim 3
Dependent Claim
28 words
A line control unit according to claim 1, wherein said optoelectronic coupling circuits comprise a photoemitting diode and a phototransistor having the base consisting of a photosensitive material.
Claim 4
Dependent Claim
39 words
A line control unit according to claim 2, wherein each of said electronic switches comprises a transistor having the emitter-collector circuit connected in series with said line and the base-collector circuit controlled by the output of the corresponding phototransistor.
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) | 1978-07-07 | 1979-01-06 | 1979-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-07 | 1983-01-06 | 1983-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-07 | 1987-01-06 | 1987-07-08 | $7700.00 | Window Closed / Lapsed |