US 12,085,746 B2
Backlight unit and liquid crystal display device
Fumitake Mitobe, Minamiashigara (JP); Keisuke Kodama, Minamiashigara (JP); Katsumi Sasata, Minamiashigara (JP); and Yukito Saitoh, Minamiashigara (JP)
Assigned to FUJIFILM Corporation, Tokyo (JP)
Filed by FUJIFILM Corporation, Tokyo (JP)
Filed on Jan. 25, 2022, as Appl. No. 17/583,433.
Application 17/583,433 is a continuation of application No. PCT/JP2020/028676, filed on Jul. 27, 2020.
Claims priority of application No. 2019-138175 (JP), filed on Jul. 26, 2019.
Prior Publication US 2022/0146742 A1, May 12, 2022
Int. Cl. F21V 8/00 (2006.01); G02B 5/18 (2006.01)
CPC G02B 6/0055 (2013.01) [G02B 5/1833 (2013.01); G02B 6/0025 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A backlight unit comprising:
a light guide plate that has first and second long side surfaces and first and second short side surfaces;
a first light source that emits light such that the light is incident into the light guide plate from at least one of the first and second short side surfaces of the light guide plate;
a second light source that emits light such that the light is incident into the light guide plate from at least one of the first and second long side surfaces of the light guide plate;
a first diffraction element that is provided on one main surface of the light guide plate and diffracts only light emitted from the first light source;
a second diffraction element that is provided on another main surface of the light guide plate opposite to the first diffraction element and diffracts only light emitted from the second light source; and
a reflection plate that is provided on a main surface of the light guide plate opposite to a light emission surface.