TELEPHONE EQUIPMENT

PROBLEM TO BE SOLVED: To turn on the back light of an LCD with sufficient lightness even in the case of a connection to an exchange for supplying a little station current at the time of trickle charging. SOLUTION: Concerning this telephone equipment, when a user performs off-hook for calling, a hook...

Full description

Saved in:
Bibliographic Details
Main Authors MUROI JUNICHI, HAYASHI KATSUHIKO, IWASAKI WATARU
Format Patent
LanguageEnglish
Published 06.10.2000
Edition7
Subjects
ELECTRIC COMMUNICATION TECHNIQUE
ELECTRICITY
TELEPHONIC COMMUNICATION
Online AccessGet full text

Cover

More Information
Summary:PROBLEM TO BE SOLVED: To turn on the back light of an LCD with sufficient lightness even in the case of a connection to an exchange for supplying a little station current at the time of trickle charging. SOLUTION: Concerning this telephone equipment, when a user performs off-hook for calling, a hook switch HS is closed, the DC loop of lines L1 and L2 are closed and the station current from the exchange flows to a speech circuit 4 or control circuit 6. A part of an excessive current excepting for a current to be consumed by the speech circuit 4 or control circuit 6 flows through a Zener diode ZD1 and a resistor R6 in an excessive current detecting part 10 to the base of a transistor Q5 and is detected by the transistor Q5 and the transistor Q5 is turned on. Thus, a transistor Q6 in a back light ON control part 11 is turned on and most of excessive currents flow through the turned-on transistor Q6 to an LED 9 for back light and the LED 9 for back light is turned on.
Bibliography:Application Number: JP19990084280