| 摘要 |
PURPOSE:To vary easily backlighting luminance by providing a voltage control circuit, which changes a DC voltage, in the preceding stage of an inverter to control the luminance of a liquid crystal plate illuminating cold cathode tube. CONSTITUTION:Different voltages corresponding to differences between an output voltage VPS of a power source 8 and voltages of Zener diodes ZD1-ZD4 are generated in a resistance R, and a changeover switch SW is operated to vary an input voltage VIN of the inverter 9 are applied to a cold cathode tube 10 to change its luminance. |
