US3665489A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone instrument for voice frequency choice of number
Assignee: Telefonaktiebolaget LM Ericsson AB
•
Filing: 1970-05-20
•
Granted: 1972-05-23
•
Expires: 1990-05-20
Abstract
Abstract There is disclosed a voice frequency oscillator included in a telephone instrument for voice frequency signalling, wherein the frequency of the oscillator can be set to predetermined values by the influence of certain contacts. The oscillator includes a circuit which in calling state is connected in series with the line loop of the telephone instrument. This circuit determines, by voltage dividing, the operating point of the oscillator. The circuit comprises two parallel branches with different impedance values, which by a make-and-break contact can be alternatively connected to the line loop for providing two different values of current passing through the line for signalling two different states.
Inventors
- 👤 Herman Josef Burghardt Vollmer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:03
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/26; H04M1/30; H04M1/50
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
163 words
In a telephone instrument for voice frequency key dialing which is connectable to a line loop and which includes at least one voice frequency oscillator which is controllable connectable in series with said line loop, a circuit which by voltage dividing controls the operating poInt of the oscillator, said circuit comprising first and second terminals, a first switch having first and second fixed contacts and a transfer contact which is switchable between said first and second fixed contacts, said transfer contact being connected to said first terminal, a first impedor having one end connected to said first contact and a second end, a second impedor having one end connected to said second contact and a second end, said first impedor having a greater impedance value than said second impedor, means for connecting the second ends of said impedors to said second terminal, and means for connecting said first and second terminals to the oscillator whereby the circuit controls the current to the oscillator.
Claim 2
Dependent Claim
163 words
In a telephone instrument for voice frequency key dialing which is connectable to a line loop and which includes at least one voice frequency oscillator which is controllable connectable in series with said line loop, a circuit which by voltage dividing controls the operating poInt of the oscillator, said circuit comprising first and second terminals, a first switch having first and second fixed contacts and a transfer contact which is switchable between said first and second fixed contacts, said transfer contact being connected to said first terminal, a first impedor having one end connected to said first contact and a second end, a second impedor having one end connected to said second contact and a second end, said first impedor having a greater impedance value than said second impedor, means for connecting the second ends of said impedors to said second terminal, and means for connecting said first and second terminals to the oscillator whereby the circuit controls the current to the oscillator.
Claim 3
Dependent Claim
72 words
The circuit of claim 1 and further comprising a second switch, a variable resistor connected in series with said second switch, and means for connecting said second switch and said variable resistor in parallel with said first switch and said impedors, said switches being ganged in such a way that said variable resistor is connected in parallel with said second impeder when said first switch connects said second impedor to the oscillator.
References Cited (Backward Citations)
US2812383A
Cited
GB906158A
Cited
US3184554A
Cited
US3454726A
Cited
US3424870A
Cited
US3476881A
Cited
US3508013A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-23 | 1975-11-22 | 1976-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-23 | 1979-11-22 | 1980-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-23 | 1983-11-22 | 1984-05-23 | $7700.00 | Window Closed / Lapsed |