1. Field of the Invention
The present invention relates to an illumination apparatus for a display device used in a liquid crystal panel or the like, a display device including the same, and a television receiver apparatus including the display device.
2. Description of the Related Art
Japanese Patent Laid-Open No. 2000-11728 (FIG. 1) describes a conventional device relating to a backlight apparatus for a liquid crystal display device. In that device, a plurality of optical sheets are laminated and disposed so as to face a light source housing portion, such that light emitted from the light source is uniformly radiated onto a display by the optical sheets.
In some cases, optical sheets that have directionality with respect to the top and bottom surfaces are included among the plurality of optical sheets. If an optical sheet of this kind is mistakenly disposed with the top and bottom surfaces on the opposite sides, correct illumination cannot be performed for the display and a display device that uses that illumination apparatus will be unable to properly display an image.
According to the prior art as described in Japanese Patent Laid-Open No. 2000-11728, an ear portion is caused to protrude from one edge of each optical sheet, and the ear portions are formed at respectively different positions among the optical sheets. Therefore, since the positions of the ear portions will be irregular when any of the optical sheets are mistakenly disposed with their top and bottom surfaces inverted, it is possible to easily discover that the top and bottom surfaces are mistakenly disposed.
However, according to the above described prior art, because the ear portions protrude from the optical sheets, the size of a housing that stores the optical sheets is increased by the size of the ear portions and the size of the overall illumination apparatus thus increases. In order to reduce the size of the apparatus, it is necessary to reduce the external shape of the optical sheets, but if the optical sheets are provided with the ear portions as they are, the active area of the optical sheets will be decreased.