Patent US3943301A successfully refreshed from Google Patents.
US3943301A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solid state four-wire switch for key telephones
Assignee: Individual
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Filing: 1974-10-07
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Granted: 1976-03-09
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Expires: 1994-10-07
Abstract
Abstract A compact, solid state four-wire switch for use with key telephones. The switch comprises a pair of transistors which, in the two-wire mode, electrically connect a telephone receiver with a telephone circuit balance network. In the four-wire mode a negative potential derived from the four-wire station pickup relay turns off the switch by reverse biasing the switch transistors to thereby electrically isolate the receiver from the balance network. The transistors are encapsulated within a thin, generally rectangular housing module which is adapted to be mounted interiorly of a key telephone on any of the pre-punched mounting holes therein. Electrical connection with the telephone circuitry is facilitated by three screw down terminals mounted on the module and three module leads equipped with terminal connectors.
Inventors
- 👤 John W. Ervin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:48
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/002
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
222 words
A solid state switch for switching between a two-wire operating mode and a four-wire operating mode in a telephone, said telephone including a two-wire circuit comprising a pair of conductor lines connected with a telephone balance network for operation in the two-wire mode and a four-wire circuit having a pair of receiver lines bypassing the balance network for operation in the four-wire mode, the switch comprising: first and second network lines adapted to be electrically connected to the telephone balance network; first and second receiver terminals adapted to be electrically connected to a telephone receiver; solid state switching means for electrically connecting said first network line to said first receiver terminal and said second network line to said second receiver terminal in the two-wire mode, said switching means having means for electrically coupling said first and second receiver terminals with the respective four-wire receiver lines, said switching means comprising a pair of transistors each having base, emitter, and collector electrodes, said base electrodes resistively coupled to ground, said emitter electrodes connected to the respective network lines, and said collector electrodes connected to the respective receiver terminals; and reverse biasing means for turning off said switching means in a four-wire mode to thereby electrically isolate said network lines from said receiver terminals while electrically coupling said four-wire receiver lines with said receiver terminals.
Claim 2
Dependent Claim
222 words
A solid state switch for switching between a two-wire operating mode and a four-wire operating mode in a telephone, said telephone including a two-wire circuit comprising a pair of conductor lines connected with a telephone balance network for operation in the two-wire mode and a four-wire circuit having a pair of receiver lines bypassing the balance network for operation in the four-wire mode, the switch comprising: first and second network lines adapted to be electrically connected to the telephone balance network; first and second receiver terminals adapted to be electrically connected to a telephone receiver; solid state switching means for electrically connecting said first network line to said first receiver terminal and said second network line to said second receiver terminal in the two-wire mode, said switching means having means for electrically coupling said first and second receiver terminals with the respective four-wire receiver lines, said switching means comprising a pair of transistors each having base, emitter, and collector electrodes, said base electrodes resistively coupled to ground, said emitter electrodes connected to the respective network lines, and said collector electrodes connected to the respective receiver terminals; and reverse biasing means for turning off said switching means in a four-wire mode to thereby electrically isolate said network lines from said receiver terminals while electrically coupling said four-wire receiver lines with said receiver terminals.
Claim 3
Dependent Claim
31 words
The combination as in claim 1, wherein said reverse biasing means comprises means interconnected with said transistor base electrodes for turning off said transistors in response to an externally supplied voltage.
Claim 4
Dependent Claim
26 words
The combination as in claim 2, including means for housing said switching means, said housing means being adapted to be attached to a perforated mounting surface.
Claim 5
Dependent Claim
15 words
The combination as in claim 3, wherein said transistors are encapsulated within said housing means.
Claim 6
Dependent Claim
109 words
The combination as in claim 1, wherein said switching means comprises: a first transistor having a base electrode, an emitter electrode connected to said first network line, and a collector electrode connected to said first receiver terminal; a reverse biasing node; a first resistor for connecting said first transistor base electrode to said reverse biasing node; a second transistor having a base electrode, an emitter electrode connected to said second network line, and a collector electrode connected to said second receiver terminal; a second resistor for connecting said second transistor base electrode to said reverse biasing node; and a third resistor for connecting said reverse biasing node to ground.
Claim 7
Dependent Claim
36 words
The combination as in claim 5, wherein said reverse biasing means comprises: a disable terminal adapted to be connected with a source of voltage; and means for connecting said disable terminal with said reverse biasing node.
Claim 8
Dependent Claim
26 words
The combination as in claim 6, including means for housing said switching means, said housing means being adapted to be attached to a perforated mounting surface.
Claim 9
Dependent Claim
25 words
The combination as in claim 7, wherein said first and second transistors and said first, second, and third resistors are encapsulated within said housing 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) | 1979-03-09 | 1979-09-08 | 1980-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-09 | 1983-09-08 | 1984-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-09 | 1987-09-08 | 1988-03-09 | $7700.00 | Window Closed / Lapsed |