Fluorescent lamps with current-mode driver control

A lamp driver circuit for current mode control of the light intensity of a fluorescent lamp comprising:

• a fluorescent lamp,
• a transformer having a primary winding and a secondary winding, said secondary winding being connected to said fluorescent lamp,
• a resonant bridge transformer driver circuit having a first side and a second side, said second side being connected across said primary winding of said transformer,
• a series inductance means connected between the first side of said resonant bridge transformer driver circuit and a source of input power signal,
• a current sensing resistance means connected between the first side of said resonant bridge transformer driver circuit and said source of input power signal,
• a switching means connected to said series inductance means and said first side of said resonant bridge transformer driver circuit,
• a pulse-width modulator means for producing a pulse width modulated signal S.sub.PWMc that is connected to said switching means to alternately open and close said switching means at a frequency representative of said pulse-width of said pulse-width signals, said opening and closing of said switching means causing the field of said series inductance means to fluctuate,
• a synchronous clock generator means connected to said pulse-width modulator means to provide a synchronous clock signal,
• a signal tap connecting said current sensing resistance to said pulse-width modulator to provide a current-sense signal S.sub.i to said pulse width modulator means,
• a processor means for providing a brightness level reference signal S.sub.r and a current regulation signal S.sub.PWMg, said processor means being connected to a selected brightness level signal and to a clock signal from said synchronous clock generator means,
• said pulse-width modulator means being connected to said processor means and responsive to said S.sub.r signal therefrom and to said S.sub.i signal from said signal tap to width modulate said S.sub.i signal by said S.sub.r signal to produce said S.sub.PWMc pulse-width modulated signal connected to said switching means.