Patent ID: 8582055

Claim:
A backlight device comprising: a first light emitting unit configured to emit light and including a first light guide plate and a pair of first light sources placed on both end faces of the first light guide plate; a second light emitting unit configured to emit light and including a second light guide plate and a pair of second light sources placed on both end faces of the second light guide plate; a third light emitting unit configured to emit light and being placed on an opposite side of the second light emitting unit from the first light emitting unit, the third light emitting unit including a third light guide plate and a pair of third light sources placed on both end faces of the third light guide plate; a first reflector placed in either side region of a face of the second light guide plate on an opposite side from the first light emitting unit; a second reflector placed in a center region of a face of the third light guide plate on an opposite side from the second light emitting unit; and a semi-transmissive reflector placed between the first light emitting unit and the second light emitting unit, the semi-transmissive reflector having a higher reflectance with respect to light incident on a first face facing the first light emitting unit than a reflectance with respect to light incident on a second face facing the second light emitting unit, the semi-transmissive reflector having a higher transmittance with respect to the light incident on the second face than a transmittance with respect to the light incident on the first face.