| 摘要 |
A back light apparatus includes an external light quantity detecting unit having a first and second light quantity detecting sections, both of which are provided at a predetermined position of the housing, a first polarizing plate provided on a light receiving surface of the first light quantity detecting section, which first polarizing plate has a polarizing axis perpendicular to that of a polarizing plate provided on the rear surface side of the liquid crystal panel, a second polarizing plate provided on the light receiving surface of the second light quantity detecting section, which second polarizing plate has 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 section to calculate the external light quantity based on the difference value between light quantities detected by the first and second light quantity detecting sections. |
