Patent US3220012A successfully refreshed from Google Patents.
US3766321A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Input circuit for an automatic telephone answering device
Assignee: Individual
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Filing: 1972-02-24
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Granted: 1973-10-16
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Expires: 1992-02-24
Abstract
Abstract An input circuit for an automatic telephone answering device includes a first series circuit, connected between telephone lines, of a DC current blocking circuit and a connecting circuit, such as a transformer, for receiving signals from telephone lines and transmitting signals from the answering device. A rectifier circuit is connected with the first series circuit in parallel. A second series circuit is connected with the rectifier circuit and consists of a contactless or electronic switching device, such as a transistor, and an AC current blocking circuit. A starting circuit is connected between the telephone lines for switching the switching device to an ON state after receiving an incoming calling signal, thereby making it possible to close the DC loop of the telephone lines through the contactless switching device.
Inventors
- 👤 T Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:18
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/64; H04M1/65; H04M1/654
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
115 words
DC current blocking circuit means for blocking DC current, and 2. connecting circuit means for receiving signals from the telephone lines and transmitting signals from an automatic telephone answering device; b. rectifier circuit means connected to said first series circuit for rectifying incoming signals; c. a second series circuit connected to said rectifier circuit means and comprising in series: 1. electronic switching means normally being in a nonconducting state, and 2. ripple current blocking circuit means for blocking a voice signal current component, and d. means for applying said control signal to said switching means to switch it to a conducting state, thereby closing a DC loop of said telephone lines through said switching means.
Claim 2
Dependent Claim
115 words
DC current blocking circuit means for blocking DC current, and 2. connecting circuit means for receiving signals from the telephone lines and transmitting signals from an automatic telephone answering device; b. rectifier circuit means connected to said first series circuit for rectifying incoming signals; c. a second series circuit connected to said rectifier circuit means and comprising in series: 1. electronic switching means normally being in a nonconducting state, and 2. ripple current blocking circuit means for blocking a voice signal current component, and d. means for applying said control signal to said switching means to switch it to a conducting state, thereby closing a DC loop of said telephone lines through said switching means.
Claim 3
Dependent Claim
61 words
An input circuit for an automatic telephone answering device adapted to be coupled to a pair of telephone lines and including starting circuit means responsive to a calling signal on the lines to produce a control signal for initiating operation of the answering device, said circuit comprising: a. a first series circuit connected between the telephone lines and comprising in series:
Claim 4
Dependent Claim
61 words
An input circuit for an automatic telephone answering device adapted to be coupled to a pair of telephone lines and including starting circuit means responsive to a calling signal on the lines to produce a control signal for initiating operation of the answering device, said circuit comprising: a. a first series circuit connected between the telephone lines and comprising in series:
Claim 5
Dependent Claim
38 words
An input circuit for an automatic telephone answering device as set forth in claim 1 wherein said switching means comprises a normally non-conducting transistor which becomes conducting when it receives the control signal from said starting circuit means.
Claim 6
Dependent Claim
44 words
ripple current blocking circuit means for blocking a voice signal current component, and d. means for applying said control signal to said switching means to switch it to a conducting state, thereby closing a DC loop of said telephone lines through said switching means.
Claim 7
Dependent Claim
44 words
ripple current blocking circuit means for blocking a voice signal current component, and d. means for applying said control signal to said switching means to switch it to a conducting state, thereby closing a DC loop of said telephone lines through said switching means.
Claim 8
Dependent Claim
48 words
connecting circuit means for receiving signals from the telephone lines and transmitting signals from an automatic telephone answering device; b. rectifier circuit means connected to said first series circuit for rectifying incoming signals; c. a second series circuit connected to said rectifier circuit means and comprising in series:
Claim 9
Dependent Claim
48 words
connecting circuit means for receiving signals from the telephone lines and transmitting signals from an automatic telephone answering device; b. rectifier circuit means connected to said first series circuit for rectifying incoming signals; c. a second series circuit connected to said rectifier circuit means and comprising in series:
Claim 10
Dependent Claim
36 words
An input circuit for an automatic telephone answering device as set forth in claim 1 wherein said DC current blocking circuit means is a condenser and said ripple current blocking circuit means is a choke coil.
Claim 11
Dependent Claim
24 words
An input circuit for an automatic telephone answering device as set forth in claim 3, wherein said connecting circuit means is a matching transformer.
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) | 1976-10-15 | 1977-04-16 | 1977-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-15 | 1981-04-16 | 1981-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-15 | 1985-04-16 | 1985-10-16 | $7700.00 | Window Closed / Lapsed |