In the related art, as a backlight unit of a liquid crystal display device using a solid light source element (for example, an LED element) as a light source for illumination, there have been a type called a direct type in which, for example, an LED element is arranged over the whole surface as a light source at a back side of a liquid crystal panel via an optical element, and a type called a side lamp type (or a side edge type) in which a light guide plate is provided at the back side of the liquid crystal panel and the LED elements are arranged in a thickness direction thereof in a line form.
For example, a backlight unit 1 of a direct type illustrated in FIG. 9 is provided with an LED backlight array 2 in which a plurality of LEDs as a light source are vertically and horizontally arranged, and a reflection plate 4 fixed to a back chassis 3 is provided at the back side thereof. A dual brightness enhancement film (DBEF) 5 which diffuses light emitted from the plurality of LEDs in a travelling direction of light, a prism film 6, and a diffusion film 7 are sequentially disposed in a light-emitting direction of the LEDs. Furthermore, at the back side of the back chassis 3, a drive circuit board 11, which drives the LEDs and a liquid crystal panel 10, is provided.
Moreover, the liquid crystal panel 10 is disposed at a further light-emitting side of the diffusion film 7 in the backlight unit 1, and thus these components constitute a liquid crystal display device 12.
The direct type backlight unit 1 has a configuration in which the plurality of LEDs are arranged to face the whole back of the liquid crystal panel 10.
As a related art that includes such a direct type backlight unit, for example, there are inventions described in Patent Documents 1, 2 and 3.
Furthermore, in a side lamp type backlight unit 14 in a liquid crystal display device 12 illustrated in FIG. 10, as in the above-mentioned direct type backlight unit 1, the drive circuit board 11, the back chassis 3, the reflection plate 4, the brightness enhancement film (DBEF) 5, the prism film 6, and the diffusion film 7 are sequentially arranged from the back side. Furthermore, a light guide plate 15 is disposed between the reflection plate 4 and the brightness enhancement film 5, and an LED backlight array 16, in which the LEDs are arranged in a line along a side of the light guide plate 15 in a thickness direction, is provided.
Moreover, the liquid crystal panel 10 is disposed at a further light-emitting side of the backlight unit 14.