DEVICE FOR CONTROLLING FLUORESCENT LAMPS PROVIDED WITH LIGHT REDUCING SCREEN

摘要

The invention relates to a lamp controller comprising a dimmer circuit for operating in response to a control voltage from a control voltage source to control a high frequency AC lamp-energizing source of said lamp controller and to thereby control light intensity, said dimmer circuit comprising: an isolation transformer including coupled primary and secondary winding means, means for applying a high frequency current from said controller to said primary winding means, input terminals for connection to said control voltage source, loading means coupled to said secondary winding means and to said input terminals and arranged to limit the voltage across said secondary winding means as a function of said control voltage and to thereby limit the high frequency voltage developed across said primary winding means from said high frequency current, and detector and output means for developing and applying to said controller an output signal for control of lamp intensity which corresponds to the high frequency voltage developed across said primary winding means, said loading means including amplifier means and being arranged to respond to a small control current through said voltage source to produce amplified and substantially equal loading currents in said secondary winding means in both half cycles of said high frequency current applied to said primary winding means.