Patent US4648109A successfully refreshed from Google Patents.
US4648109A
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US
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Light emitting diode message waiting lamp circuit
Assignee: AG Communication Systems Corp
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Filing: 1985-12-16
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Granted: 1987-03-03
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Expires: 2005-12-16
Abstract
Abstract A circuit providing a message waiting indication using a light emitting diode and a constant current surge protected circuit for use with PABX extension telephone instruments. Recently developed light emitting diodes operated with current of one milliampere or less are effectively used in the present circuitry which limits current to the device in the operating mode and also as low leakage current while in the "off" mode.
Inventors
- 👤 Eduard F. B. Boeckmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:42
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/82; H04M3/00; H04M3/42; H04M3/50; H04M3/53; H04M3/537
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
92 words
A message waiting lamp circuit included in a telephone instrument connected to a central switching point, via a telephone line, said lamp circuit comprising: a light emitting diode; a constant current source connected to said diode; gating means connected between said telephone line and said constant current source; said constant current source operated in response to conduction of voltages above a predetermined threshold by said gating means from said central switching point via said telephone line, to provide operating current for said light emitting diode whereby said light emitting diode is operated.
Claim 2
Dependent Claim
92 words
A message waiting lamp circuit included in a telephone instrument connected to a central switching point, via a telephone line, said lamp circuit comprising: a light emitting diode; a constant current source connected to said diode; gating means connected between said telephone line and said constant current source; said constant current source operated in response to conduction of voltages above a predetermined threshold by said gating means from said central switching point via said telephone line, to provide operating current for said light emitting diode whereby said light emitting diode is operated.
Claim 3
Dependent Claim
63 words
A message waiting lamp circuit as claimed in claim 1, wherein: said voltage received from said central switching point via said telephone line is representative of a message waiting signal whereby said light emitting diode is operated to a steady state and in the alternative said voltage is representative of ringing signal whereby said light emitting diode is operated to a pulsing state.
Claim 4
Dependent Claim
41 words
A message waiting lamp circuit as claimed in claim 1, wherein: there is further included a polarity guard connected between said telephone line and said gating means, operated to insure that potential of proper polarity is conducted to said gating means.
Claim 5
Dependent Claim
19 words
A message waiting lamp circuit as claimed in claim 3, wherein: said polarity guard comprises a diode bridge circuit.
Claim 6
Dependent Claim
25 words
A message waiting lamp circuit as claimed in claim 1, wherein: said constant current source comprises a composite transistor circuit including first and second transistors.
Claim 7
Dependent Claim
28 words
A message waiting lamp circuit as claimed in claim 5, wherein: said first transistor is of the PNP type and said second transistor is of the NPN type.
Claim 8
Dependent Claim
21 words
A message waiting lamp circuit as claimed in claim 6, wherein: said constant current source further includes a reference current source.
Claim 9
Dependent Claim
26 words
A message waiting lamp circuit as claimed in claim 7, wherein: said reference current source is a resistor of between 700,000 and 800,000 Ohms in value.
Claim 10
Dependent Claim
19 words
A message waiting lamp circuit as claimed in claim 5, wherein: said constant current source further includes protective means.
Claim 11
Dependent Claim
18 words
A message waiting lamp circuit as claimed in claim 9, wherein: said protective circuit comprises a zener diode.
Claim 12
Dependent Claim
18 words
A message waiting lamp circuit as claimed in claim 1, wherein: said gating means comprise a zener diode.
Claim 13
Dependent Claim
18 words
A message waiting lamp circuit as claimed in claim 1, wherein: there is further included voltage regulation means.
Claim 14
Dependent Claim
19 words
A message waiting lamp circuit as claimed in claim 12, wherein: said voltage regulation means comprise a zener diode.
Claim 15
Dependent Claim
38 words
A message waiting lamp circuit as claimed in claim 1, wherein: there is further included current limiting means connected between said gating means and said constant current source operated to limit current at voltages above a predetermined level.
Claim 16
Dependent Claim
18 words
A message waiting lamp circuit as claimed in claim 14, wherein: said current limiting means comprise a resistor.
Claim 17
Dependent Claim
22 words
A message waiting lamp circuit as claimed in claim 1, wherein: there is further included protection means for said light emitting diode.
Claim 18
Dependent Claim
17 words
A message waiting lamp circuit as claimed in claim 16, wherein: said protection means comprise a diode.
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) | 1990-03-02 | 1990-09-01 | 1991-03-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-02 | 1994-09-01 | 1995-03-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-02 | 1998-09-01 | 1999-03-03 | $7700.00 | Window Closed / Lapsed |