US4092496A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable impedance detecting circuit for a telephone line auxiliary device
Assignee: Pioneer Corp
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Filing: 1976-10-07
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Granted: 1978-05-30
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Expires: 1996-10-07
Abstract
Abstract An automatic telephone answering device includes a diode bridge rectifier having its input terminals connected across a pair of telephone lines through a first switch, and its output terminals connected across a relay coil through a voltage controlled impedance, such as a Zener diode. A relatively high frequency, high voltage call signal is rectified by the bridge and breaks down the diode to energize the relay coil. This closes a relay switch to actuate a control circuit, whose outputs a) actuate a tape recorder unit to play back a prerecorded message to the caller, and b) simultaneously transfer the first switch to connect the tape recorder unit across the telephone lines through a line transformer. The breakdown voltage of the Zener diode is selected to be above the voltage level produced by sound (conversation) signals and busy tone signals, whereby the device presents a high impedance to such signals and is not actuated thereby.
Inventors
- 👤 Shizuo Ando
- 👤 Hiroshi Mizuno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:49
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/64; H04M1/65; H04M1/654
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
177 words
Variable impedance detecting circuit for a telephone line auxiliary device including a pair of telephone lines for transmitting relatively low frequency, high voltage call signals and relatively high frequency, low voltage sound signals and busy tone signals, comprising: (a) voltage-controlled variable impedance means for presenting a low impedance to incoming call signals and a high impedance to incoming sound signals and busy tone signals, (b) circuit means for producing an output signal in response to the presentation of a low impedance by said variable impedance means comprising a diode bridge rectifier having one input terminal connected to one of said telephone lines through a capacitor and a first switch and the other input terminal directly connected to the other of said telephone lines, a relay coil having one end directly connected to one output terminal of said bridge and the other end connected to the other output terminal of said bridge through said variable impedance means, and a second switch controlled by said relay coil, and (c) auxiliary circuit means operable in response to said output signal.
Claim 2
Dependent Claim
177 words
Variable impedance detecting circuit for a telephone line auxiliary device including a pair of telephone lines for transmitting relatively low frequency, high voltage call signals and relatively high frequency, low voltage sound signals and busy tone signals, comprising: (a) voltage-controlled variable impedance means for presenting a low impedance to incoming call signals and a high impedance to incoming sound signals and busy tone signals, (b) circuit means for producing an output signal in response to the presentation of a low impedance by said variable impedance means comprising a diode bridge rectifier having one input terminal connected to one of said telephone lines through a capacitor and a first switch and the other input terminal directly connected to the other of said telephone lines, a relay coil having one end directly connected to one output terminal of said bridge and the other end connected to the other output terminal of said bridge through said variable impedance means, and a second switch controlled by said relay coil, and (c) auxiliary circuit means operable in response to said output signal.
Claim 3
Dependent Claim
18 words
An auxilliary apparatus as defined in claim 1, wherein said auxilliary circuit means comprises a remote bell device.
Claim 4
Dependent Claim
44 words
Variable impedance detecting circuit as defined in claim 1, wherein said auxiliary circuit means comprises a tape recorder unit, and said output signal actuates said tape recorder unit and simultaneously transfers said first switch to connect said tape recorder unit across said telephone lines.
Claim 5
Dependent Claim
17 words
Variable impedance detecting circuit as defined in claim 1, wherein said variable impedance means comprises Zener diode.
Claim 6
Dependent Claim
44 words
Variable impedance detecting circuit as defined in claim 1, wherein said variable impedance means comprises a Zener diode, said other output terminal fo said bridge is a positive output terminal, and the anode of said Zener diode is connected to said positive output terminal.
Claim 7
Dependent Claim
17 words
Variable impedance detecting circuit as defined in claim 1, wherein said variable impedance means comprises a varistor.
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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) | 1981-05-29 | 1981-11-28 | 1982-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-29 | 1985-11-28 | 1986-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-29 | 1989-11-28 | 1990-05-30 | $7700.00 | Window Closed / Lapsed |