Patent US4189626A successfully refreshed from Google Patents.
US4189626A
Expired / Lapsed
US
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Electronic tone ringer for telephone sets
Assignee: Telecom Italia SpA
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Filing: 1978-06-16
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Granted: 1980-02-19
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Expires: 1998-06-16
Abstract
Abstract A tone ringer for a telephone set, responsive to both low-voltage call signals of relatively high frequency and high-voltage call signals of a relatively low frequency, comprises an active filter connected across a line loop for transmitting the low-frequency call signals in attenuated form and the high-frequency call signals in amplified form to a storage capacitor in a signal detector which in the presence of either type of call signal accumulates a sufficient charge to activate a threshold circuit in that detector. A normally blocked current source, connected across the line loop via a diode bridge, is unblocked by this threshold circuit to energize a tone generator working into an electro-acoustic transducer.
Inventors
- 👤 Oreste Malerba
- 👤 Antonio Neri
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:22
CPC Classifications
H; H04; H04M; H04M19/00; H04M19/02; H04M19/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
140 words
A tone ringer for a telephone set receiving call signals from an exchanger over a line loop normally energized with d-c voltage, said call signals including a lower-voltage signal of relatively high frequency and a higher-voltage signal of relatively low frequency, comprising: a normally blocked current source connected across said line loop; filter means with a pass band encompassing the frequencies of said call signals connected across said line loop; charge-accumulating means connected to said filter means for developing a progressively rising voltage in the presence of a call signal; a threshold circuit connected to said charge-accumulating means for activation by said progressively rising voltage upon the same attaining a predetermined level, said current source being connected to said threshold circuit for unblocking upon activation of the latter; and a tone generator connected to said current source for energization thereby.
Claim 2
Dependent Claim
140 words
A tone ringer for a telephone set receiving call signals from an exchanger over a line loop normally energized with d-c voltage, said call signals including a lower-voltage signal of relatively high frequency and a higher-voltage signal of relatively low frequency, comprising: a normally blocked current source connected across said line loop; filter means with a pass band encompassing the frequencies of said call signals connected across said line loop; charge-accumulating means connected to said filter means for developing a progressively rising voltage in the presence of a call signal; a threshold circuit connected to said charge-accumulating means for activation by said progressively rising voltage upon the same attaining a predetermined level, said current source being connected to said threshold circuit for unblocking upon activation of the latter; and a tone generator connected to said current source for energization thereby.
Claim 3
Dependent Claim
35 words
A tone ringer as defined in claim 1 wherein said filter means comprises an active filter including an operational amplifier with a higher gain at said relatively high frequency than at said relatively low frequency.
Claim 4
Dependent Claim
26 words
A tone ringer as defined in claim 2 wherein said operational amplifier has a maximum gain at substantially 500 Hz and attenuates oscillations of 25 Hz.
Claim 5
Dependent Claim
33 words
A tone ringer as defined in claim 1, 2 or 3 wherein said charge-accumulating means comprises a storage capacitor in series with a charging diode and a discharge resistor shunting said storage capacitor.
Claim 6
Dependent Claim
35 words
A tone ringer as defined in claim 4 wherein said threshold circuit comprises a normally nonconductive control transistor with a base and an emitter connected in series with a Zener diode across said storage capacitor.
Claim 7
Dependent Claim
78 words
A tone ringer as defined in claim 5 wherein said current source is connected to said line loop through a voltage stabilizer, said control transistor having a collector connected to an output lead of said voltage stabilizer via a series resistor, said current source including another transistor with an emitter and a base respectively connected to said output lead and to said series resistor for conducting only in the presence of a voltage drop across said series resistors.
Claim 8
Dependent Claim
60 words
A tone ringer as defined in claim 6 wherein said voltage stabilizer and said current source comprise two further transistors connected in series, each of said further transistors having a base lead including a respective Zener diode, said output lead being connected to a junction between a collector of one and an emitter of the other of said further transistors.
Claim 9
Dependent Claim
22 words
A tone ringer as defined in claim 6, further comprising a diode bridge inserted between said line loop and said voltage stabilizer.
Claim 10
Dependent Claim
46 words
A tone ringer as defined in claim 1, 2 or 3 wherein said tone generator comprises two oscillators of different operating frequencies and a modulator connected to said oscillators for modulating the higher one of said operating frequencies with the lower one of said operating frequencies.
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) | 1983-02-18 | 1983-08-20 | 1984-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-02-18 | 1987-08-20 | 1988-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-02-18 | 1991-08-20 | 1992-02-19 | $7700.00 | Window Closed / Lapsed |