US3673329A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Combined telephone-telegraphy system
Assignee: EAGLE SIGNAL CONTROLS CORP A CORP OF
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Filing: 1968-02-09
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Granted: 1972-06-27
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Expires: 1988-02-09
Abstract
Abstract A combined telephone-telegraphy system is disclosed herein and which includes a plurality of local calling boxes and central station communication equipment connected together in a series circuit. Each local calling box includes telephone equipment for transmitting and receiving voice frequency signals to and from the central station equipment, as well as telegraphy means for transmitting coded box, identifying tone frequency signals to the central station equipment. Each local calling box also includes means for providing electrical power for the local calling box from current flow in the series circuit.
Inventors
- 👤 Foster E Weld
- 👤 Robert W Lassell
- 👤 Robert B Mcleod
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:46
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/04; H04M11/06
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
123 words
A calling box comprising voice communication means for transmitting and receiving voice frequency signals and telegraphy means for transmitting coded box identifying signals, circuit means in said calling box adapted to be connected to a current carrying conductor for developing box operating power therefrom, normally closed switching means shunting said circuit means thereby rendering said circuit means nonresponsive to current flow in said conductor until said switching means is opened, said current flow in said current carrying conductor is direct current and said circuit means includes a Zener diode connected across said normally closed switching means in such a manner with respect to the direction of said current flow that when said switching means is opened said Zener diode will be reverse biased.
Claim 2
Dependent Claim
123 words
A calling box comprising voice communication means for transmitting and receiving voice frequency signals and telegraphy means for transmitting coded box identifying signals, circuit means in said calling box adapted to be connected to a current carrying conductor for developing box operating power therefrom, normally closed switching means shunting said circuit means thereby rendering said circuit means nonresponsive to current flow in said conductor until said switching means is opened, said current flow in said current carrying conductor is direct current and said circuit means includes a Zener diode connected across said normally closed switching means in such a manner with respect to the direction of said current flow that when said switching means is opened said Zener diode will be reverse biased.
Claim 3
Dependent Claim
77 words
A calling box as set forth in claim 1 wherein said circuit means includes a pair of steering-diodes with one steering diode connected in series with said Zener diode and said other steering diode connected in parallel across said series connected Zener diode and steering diode, said steering diodes being poled with respect to each other and to said Zener diode to aid reverse biasing of said Zener diode upon opening of said normally closed switching means.
Claim 4
Dependent Claim
114 words
A calling box comprising voice communication means for transmitting and receiving voice frequency signals and telegraphy means for transmitting coded identifying frequency signals said telegraphy means including a pair of oscillator means each developing a different frequency signal, and output means for combining said different frequency signals to provide a distinctive coded frequency signal representative of said calling box, said calling box including normally closed switching means for, upon opening thereof, activating said pair of oscillator means, and time delay circuit means for deactivating said pair of oscillator means after a predetermined time subsequent to the opening of said normally closed switching means whereby said coded frequency signal is transmitted for a predetermined period.
Claim 5
Dependent Claim
114 words
A calling box comprising voice communication means for transmitting and receiving voice frequency signals and telegraphy means for transmitting coded identifying frequency signals said telegraphy means including a pair of oscillator means each developing a different frequency signal, and output means for combining said different frequency signals to provide a distinctive coded frequency signal representative of said calling box, said calling box including normally closed switching means for, upon opening thereof, activating said pair of oscillator means, and time delay circuit means for deactivating said pair of oscillator means after a predetermined time subsequent to the opening of said normally closed switching means whereby said coded frequency signal is transmitted for a predetermined period.
Claim 6
Dependent Claim
51 words
A calling box as set forth in claim 3 wherein said time delay circuit means includes on-off switch means connecting said oscillator means across said normally closed switching means, said on-off switching means being in its on condition when said normally closed switching means is opened for energizing said oscillator means.
Claim 7
Dependent Claim
81 words
A calling box as set forth in claim 4 wherein said time delay circuit means includes means for rendering said on-off switching means in its off condition after a predetermined time subsequent to opening of said normally closed switching means, said means including energy storage means connected across said normally closed switching means and control means responsive to a predetermined magnitude of energy stored by said energy storage means for causing said on-off switching means to be in its off condition.
Claim 8
Dependent Claim
31 words
A calling box as set forth in claim 5 wherein said energy storage means takes the form of a capacitor connected across said normally closed switching means via a timing resistor.
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) | 1975-06-27 | 1975-12-27 | 1976-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-27 | 1979-12-27 | 1980-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-27 | 1983-12-27 | 1984-06-27 | $7700.00 | Window Closed / Lapsed |