LIQUID CRYSTAL BACK LIGHT CIRCUIT

摘要

PROBLEM TO BE SOLVED: To alternately light lamps for illumination liquid crystals or switching the brightness thereof and to prolong their life by dividing a plurality of the lamps for illuminating the liquid crystals to plural groups and alternately lighting these lamps. SOLUTION: A control circuit 1 inputs a prescribed signal to a switching device 2. The switching device 2 alternately switches the signal from the control circuit 1 to either of a drive circuit A 3 or drive circuit B 3 by the switching signal inputted from outside. The signal to be alternately switched is the signal to be alternately switched at every on/off of a power source or every prescribed time measured by a timer. The drive circuit 3 controls the lighting of the lamps 4 in accordance with a drive signal and applies a prescribed high-frequency voltage to the primary side of a transformer and the prescribed high-frequency voltage from a secondary side to the lamps 4 to light the lamps. The lamps 4 are lighted by the voltage applied from the drive circuit 3 to illuminate the liquid crystals.