| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a planer light source device and a liquid crystal display device which can accurately carry out the control of brightness. <P>SOLUTION: The liquid crystal display device is provided with LED1 of R, G and B and a light guide plate 2 guiding light entering from an incidence plane 2c to the whole plane. Dot printing is carried out on a bottom plane 2b of the light guide plate and a dispersing part 13 dispersing the entering light is provided. Furthermore, an optical sensor 4 to receive light made incident from a side plane 2e of the light guide plate 2 and a shielding member 9, in front of an optical sensor, are provided. The shielding member 9 is provided with a pin hole 9a and the light making incidence on the optical sensor 4 from the incidence plane 2C in the direction of a facing plane 2d at an angle which is more than a specified angle can be shielded. Then, the light quantity of LED1 can be adjusted based on the light detected by the optical sensor 4. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
