Patent US3876835A successfully refreshed from Google Patents.
US3876835A
Expired / Lapsed
US
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Loudspeaking telephone instruments
Assignee: The General Electric Company PLC
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Filing: 1972-10-30
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Granted: 1975-04-08
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Expires: 1992-10-30
Abstract
Abstract In a loudspeaking telephone rectified voice-frequency signals for voice-switching from the send and receive paths are each applied to charge two capacitors which are periodically discharged in turn, the voltages across the two capacitors being applied by way of respective inputs of an "or" gate to a comparator which controls the switching circuits.
Inventors
- 👤 Bernard Sydney Barnaby
- 👤 Percy Albert Gander
- 👤 Roy James Brooker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 10:18
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/08; H04M9/10
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
216 words
A loudspeaking telephone instrument comprising a microphone, a send path for voice signals interconnecting said microphone and line terminals of the instrument, a loudspeaker, a receive path for voice signals interconnecting said line terminals and said loudspeaker, first and second switch means connected respectively in said send and receive paths, and voice switching means responsive to the relative amplitudes of voice signals applied to said send and receive paths to operate said switch means, said voice switching means comprising a first group of at least two capacitors, rectifier means to charge each capacitor of said first group in response to voice signals on said send path and means periodically to discharge each capacitor of said first group in turn, a second group of at least two capacitors, rectifier means to charge each capacitor of said second group in response to voice signals on said receive path, means periodically to discharge each capacitor of said second group in turn, a voltage comparator having first and second inputs, means to apply the voltage of greatest magnitude across any capacitor in the first group and the voltage of greatest magnitude across any capacitor in the second group to respective inputs of said comparator, and means to operate said switch means in dependence upon an output signal from said comparator.
Claim 2
Dependent Claim
216 words
A loudspeaking telephone instrument comprising a microphone, a send path for voice signals interconnecting said microphone and line terminals of the instrument, a loudspeaker, a receive path for voice signals interconnecting said line terminals and said loudspeaker, first and second switch means connected respectively in said send and receive paths, and voice switching means responsive to the relative amplitudes of voice signals applied to said send and receive paths to operate said switch means, said voice switching means comprising a first group of at least two capacitors, rectifier means to charge each capacitor of said first group in response to voice signals on said send path and means periodically to discharge each capacitor of said first group in turn, a second group of at least two capacitors, rectifier means to charge each capacitor of said second group in response to voice signals on said receive path, means periodically to discharge each capacitor of said second group in turn, a voltage comparator having first and second inputs, means to apply the voltage of greatest magnitude across any capacitor in the first group and the voltage of greatest magnitude across any capacitor in the second group to respective inputs of said comparator, and means to operate said switch means in dependence upon an output signal from said comparator.
Claim 3
Dependent Claim
20 words
A loudspeaking telephone instrument in accordance with claim 1 wherein each of said first and second groups comprises two capacitors.
Claim 4
Dependent Claim
53 words
A loudspeaking telephone instrument in accordance with claim 1 further comprising a multivibrator, said first and second means to discharge said capacitors comprising respective transistor switch means connected across each capacitor and means to bias each of said transistor switch means into conduction in dependence upon a respective output signal from said multivibrator.
Claim 5
Dependent Claim
22 words
A loudspeaking telephone instrument in accordance with claim 1 wherein said rectifier means to charge each capacitor comprises respective biphase rectifier arrangements.
Claim 6
Dependent Claim
22 words
A loudspeaking telephone instrument in accordance with claim 3 wherein each of said first and second switch means comprises a field-effect transistor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |