Title:
CIRCUIT AND METHOD FOR RINGING DETECTION OF WIRED AND WIRELESS HYBRID TELEPHONE SET
Document Type and Number:
Japanese Patent JPH09312678
Kind Code:
A
Abstract:
PROBLEM TO BE SOLVED: To shorten a delay time of termination by adding an optical coupler which cuts off the negative area of an input signal led in from a ringing detection part, and inverts and outputs the positive area and a filter which generates a ringing detection signal. SOLUTION: The voltage outputted from the ringing detection part 412 is inputted to the optical coupler which is coupled in parallel and a photodiode in the optical coupler 414 is turned on in a positive cycle of the input voltage and turned off in a negative cycle. This output voltage is passed through a capacitor C2 in a filter part 416 and only its AC component is coupled and outputted, so that it is converted into a direct current through an integrator 422 composed of a resistance R4 and a capacitor C2 in the filter part 416. This DC current is applied to the base of a transistor Q1 as an input signal and then a CPU 418 indicates ringing termination to shorten the delay time of the termination.
Inventors:
RI BAIKON
Application Number:
JP34748296A
Publication Date:
December 02, 1997
Filing Date:
December 26, 1996
Export Citation:
Assignee:
SAMSUNG ELECTRONIC
International Classes:
H04N1/00; H04M1/00; H04M1/50; H04M1/72505; H04M19/04; (IPC1-7): H04M1/00; H04N1/00
Attorney, Agent or Firm:
高月 猛