Patent US4506115A successfully refreshed from Google Patents.
US4506115A
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Message alert system
Assignee: GTE Communications Products Corp
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Filing: 1983-09-12
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Granted: 1985-03-19
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Expires: 2003-09-12
Abstract
Abstract A lamp is provided on a telephone handset to notify the user that a message is waiting. The lamp is energized by a 1 hertz square wave obtained by demodulating a high frequency carrier sent from a transmitter.
Inventors
- 👤 Paul M. Schmitt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:10
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/82; H04M3/00; H04M3/42; H04M3/50; H04M3/53; H04M3/537
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
148 words
A "message waiting" lamp system for use with a plurality of telephone handsets having individual tip and ring lines, said "message waiting' lamp system comprised of: a. a transmitter including: a signal generator for providing an out-of-band carrier signal modulated with a modulating signal, wherein said modulating signal has a ramp waveform; a gate corresponding to each handset, and having an input coupled to the signal generator and an output, said gate arranged to turn on in response to an enabling signal; a capacitor tapping the tip line of a corresponding handset and coupled to the output of said gate; and b. a receiver located in proximity to a handset, including: means for separating the modulated carrier signal from DC voltage carried by the tip line; means for demodulating said signal and obtaining a square wave; and a lamp arranged to light in response to the square wave.
Claim 2
Dependent Claim
148 words
A "message waiting" lamp system for use with a plurality of telephone handsets having individual tip and ring lines, said "message waiting' lamp system comprised of: a. a transmitter including: a signal generator for providing an out-of-band carrier signal modulated with a modulating signal, wherein said modulating signal has a ramp waveform; a gate corresponding to each handset, and having an input coupled to the signal generator and an output, said gate arranged to turn on in response to an enabling signal; a capacitor tapping the tip line of a corresponding handset and coupled to the output of said gate; and b. a receiver located in proximity to a handset, including: means for separating the modulated carrier signal from DC voltage carried by the tip line; means for demodulating said signal and obtaining a square wave; and a lamp arranged to light in response to the square wave.
References Cited (Backward Citations)
US3937889A
Cited
US3934098A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-03-18 | 1988-09-17 | 1989-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-18 | 1992-09-17 | 1993-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-18 | 1996-09-17 | 1997-03-19 | $7700.00 | Window Closed / Lapsed |