| 摘要 |
PURPOSE:To obtain a display surface having the optimum brightness, by sensing a change in light quantity of surrounding rays of light and changing the brightness of a back lighting light source in accordance with the change in light quantity. CONSTITUTION:A transmission positive type TN display element 1 is provided in front of this display device and a photodiode 7 is put adjacent to the liquid crystal display element 1. The change in surrounding rays of light is read through a change in the electric current of the photodiode 7 and inputted to a light adjusting circuit 4 from a current amplifier 6 through a current-frequency converter 5. A fluorescent lamp is used as the back lighting light source 2 of this display device and the brightness of the fluorescent lamp 2 is changed by changing a back lighting power source 3 in accordance with the output of the light adjusting circuit 4. Therefore, the display surface of this display device does not become dark even if the surrounding rays of light becomes fairly bright and, as a result, a display surface which does not give any sense of fatigue to the user even when the user watches the display surface for a long time, can be obtained. |
