Telephonic communications – Subscriber line or transmission line interface – Power supply
Reexamination Certificate
2006-07-18
2006-07-18
Tran, Sinh (Department: 2646)
Telephonic communications
Subscriber line or transmission line interface
Power supply
C323S908000
Reexamination Certificate
active
07079647
ABSTRACT:
An IP telephone has a power source circuit. A direct current from a network is used to charge an input capacitor via an input current limiting resistor. A resultantly charged voltage is inputted to and is converted by a DC/DC converter to produce an output voltage. In parallel with the input current limiting resistor, a limit removing unit including a switching transistor is arranged. The output voltage is delayed by a delay circuit to activate a driving transistor, which drives the switching transistor. The input voltage to the converter is monitored by an input voltage sensor. Therefore, the telephone power source circuit copes with a plurality of hubs of different power supplying specifications in an internet (IP) telephone network in which telephones are connected to a local-area network of the IEEE802.3 standard and the like.
REFERENCES:
patent: 4631470 (1986-12-01), Bingley
patent: 5973942 (1999-10-01), Nelson et al.
patent: 6804351 (2004-10-01), Karam
patent: 2002/0091951 (2002-07-01), Jaeger et al.
patent: 8-9071 (1996-01-01), None
patent: 2000-69206 (2000-03-01), None
Briney III Walter F
Foley & Lardner LLP
NEC Engineering Ltd.
Tran Sinh
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