| 摘要 |
PROBLEM TO BE SOLVED: To provide a back light apparatus capable of emitting light having more suitable luminance according to a surrounding external light quantity with decreased structural restriction and a liquid crystal display apparatus equipped with the back light apparatus, at low cost. SOLUTION: The back light apparatus includes: an external light quantity detecting unit for detecting a quantity of an external light entering the back light apparatus; and a back light adjusting means for adjusting luminance of the back light source based on the external light quantity, wherein the external light quantity detecting unit includes: a first light quantity detecting means and a second light quantity detecting means, both being provided at a predetermined position of a housing; a first polarizing plate provided on a light receiving surface of the first light quantity detecting means, the first polarizing plate having a polarizing axis perpendicular to that of a polarizing plate provided on a rear surface side of the liquid crystal panel; a second polarizing plate provided on a light receiving surface of the second light quantity detecting means, the second polarizing plate having the same polarizing axis as that of the polarizing plate provided on the rear surface side of the liquid crystal panel; and an external light quantity calculating means for calculating the external light quantity based on a difference value between a light quantity detected by the first light quantity detecting means and a light quantity detected by the second light quantity detecting means. COPYRIGHT: (C)2010,JPO&INPIT |
