| 摘要 |
PROBLEM TO BE SOLVED: To provide an inverter for the back light of a liquid crystal display which does not generate interference fringes on a display screen even to the liquid crystal display having different scanning frequencies, is capable of adjusting the brightness of the back light, and making a cost low. SOLUTION: In an inverter 10 for a back light, a signal for modulated light is obtained from a signal formed by dividing the scanning frequency of a liquid crystal driving signal, back light lighting voltage is controlled on and off with a modulated light signal obtained by adjusting a duty ratio according to the desirable brightness to adjust the brightness of the back light. A duty ratio adjusting degree is controlled with a voltage signal 19 obtained by frequency voltage converting the output of a dividing circuit 18, and brightness adjusting is made constant independent of the frequency. |
