Patent US19693A successfully refreshed from Google Patents.
Patent US4887295A successfully refreshed from Google Patents.
US4887295A
Expired / Lapsed
US
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Telephone instrument
Assignee: Siliconix Ltd
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Filing: 1987-06-08
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Granted: 1989-12-12
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Expires: 2007-06-08
Abstract
Abstract Telephone instruments generally comprise a mechanical hookswitch connected across the pair of speech wires. This specification discloses solid state hookswitch circuitry comprising a switching transistor controlled by a hookswitch and connected in series with the output of a rectifier, the rectifier being connected directly to the incoming speech wires. Because the hookswitch controls a switching transistor, rather than having to switch line voltages directly, any reliable low current make/break switch may be employed.
Inventors
- 👤 James O. M. Jenkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:42
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/26; H04M1/30; H04M1/31; H04M1/312; H04M1/53
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
137 words
A telephone instrument having electronic operating circuitry, and comprising a rectifier to provide, from the telephone line voltage, a d.c. supply voltage of predetermined polarity for the electronic operating circuitry, a hookswitch operable to apply the d.c. voltage from the rectifier to all of said electronic operating circuitry only when the instrument is off-hook, a first FET switching transistor connected in series with the output of the rectifier to supply the d.c. voltage from the rectifier to the operating circuitry, a second FET switching transistor responsive to the status of the hookswitch and being arranged to provide a current conduction path necessary to provide an enabling voltage to a control terminal of the first FET switching transistor, and said circuitry causing the status of the hookswitch to determine the status of the said second FET switching transistor.
Claim 2
Dependent Claim
137 words
A telephone instrument having electronic operating circuitry, and comprising a rectifier to provide, from the telephone line voltage, a d.c. supply voltage of predetermined polarity for the electronic operating circuitry, a hookswitch operable to apply the d.c. voltage from the rectifier to all of said electronic operating circuitry only when the instrument is off-hook, a first FET switching transistor connected in series with the output of the rectifier to supply the d.c. voltage from the rectifier to the operating circuitry, a second FET switching transistor responsive to the status of the hookswitch and being arranged to provide a current conduction path necessary to provide an enabling voltage to a control terminal of the first FET switching transistor, and said circuitry causing the status of the hookswitch to determine the status of the said second FET switching transistor.
Claim 3
Dependent Claim
25 words
A telephone instrument according to claim 1 having a control terminal for receiving a control signal to override the hookswitch in controlling said switching transistor.
Claim 4
Dependent Claim
36 words
A telephone instrument according to claim 2 including a line current interrupt switch operable to generate dialing pulses on the telephone lines, and dialing control pulse generating means to provide control pulses to said control terminal.
Claim 5
Dependent Claim
26 words
A telephone instrument according to claim 3 wherein the line current interrupt switch is controlled by the control pulses from said dialing control pulse generating means.
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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) | 1992-12-11 | 1993-06-12 | 1993-12-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-11 | 1997-06-12 | 1997-12-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-11 | 2001-06-12 | 2001-12-12 | $7700.00 | Window Closed / Lapsed |