Patent ID: 7391166

Claim:
A parallel lighting system for discharge lamps for a surface light source having a surface light source system and shunt transformers (CDT) including two coils, the parallel lighting system comprising: a current shunt circuit module (CD) which lights the discharge lamps in parallel, step-up transformers (T 1 , T 2 ) each including two resonance circuits, the step-up transformers (T 1 , T 2 ) generating voltage waveforms different in phase by 180 degrees from each other (−VH, +VH), and an even number of discharge lamps (DT) which are separated into two groups comprising plural discharge lamps (DT), wherein: the discharge lamps (DT) are arranged into at least two pairs each driven in opposite phases by the step-up transformers (T 1 , T 2 ), an electrode at one end of each of a first pair of discharge lamps (DT 1 , DT 2 ) is connected to the step-up transformers (T 1 , T 2 ), respectively, and electrodes at the other end of the first pair of discharge lamps (DT 1 , DT 2 ) are connected together via a first coil of a first shunt transformer (CDT 1 ), wherein the first coil of the first shunt transformer (CDT 1 ) is composed of oblique winding or section winding, an electrode at one end of each of a second pair of discharge lamps (DT 3 , DT 4 ) is connected to the step-up transformers (T 1 , T 2 ) respectively, and electrodes at the other end of the second pair of discharge lamps (DT 3 , DT 4 ) are connected together via a first coil of a second shunt transformer (CDT 2 ), wherein the first coil of the second shunt transformer (CDT 2 ) is composed of oblique winding or section winding, and a second coil of the first shunt transformer (CDT 1 ) is connected in series to a second coil of the second shunt transformer (CDT 2 ), thereby balancing lamp currents of the discharge lamps (DT) and detecting a lamp current of each of the discharge lamps (DT).