公开(公告)号：JPH05304415A

公开(公告)日：1993-11-16

申请号：JP33035692

申请日：1992-12-10

Applicant: MARELLI AUTRONICA

Inventor： ANDOREA NEPOOTE

IPC: B60Q1/04 ,  H02M7/538 ,  H03B5/08 ,  H05B41/288

Abstract: PURPOSE: To use only one capacitor to avoid a trouble due to the different values of plural capacitors by comparing a saw tooth signal from the capacitor to be alternately charged/discharged in accordance with the terminal voltage of a lamp current detecting resistor with a threshold and controlling a lamp. CONSTITUTION: The capacitor 8 is alternately charged/discharged in accordance with the terminal voltage of the lamp current detecting resistor 9 which is generated by the lamp current of a gas discharge lamp L. A current signal IL from the lamp L is inputted to a signal processing circuit 12 in a control circuit 11 and a square wave signal having the same frequency as that of the signal IL and a square wave signal having a reverse phase against the phase of the former square signal are outputted to a saw tooth wave generator 13. The generator 13 inputs a triangular wave D having twice the frequency of a signal C to a comparator 14, which compares the signal D with a reference signal to be changed depending on an external control signal. A comparison signal E from the comparator 14 is inputted to a logic circuit 15, which outputs signals J, K for controlling transistors(TRs) 3a, 3b to control the lamp current through an inverter.