Patent ID: 8376601

Claim:
A backlight unit including a light source, and a light guide plate having an incident surface on which light from the light source is incident and guides the light incident on the incident surface in a predetermined light guide direction, the backlight unit comprising: a light-emitting portion that is provided on the light guide plate side of the light source so as to be opposed to the incident surface and outputs the light from the light source toward the light guide plate, wherein a dimension on the incident surface side of the light-emitting portion in a thickness direction of the light guide plate is not more than a dimension at the incident surface of the light guide plate in its thickness direction, the light-emitting portion comprises a two-dimensional photonic crystal, a light-passing portion that is provided between the light source and the light-emitting portion and allows the light from the light source to be incident on the light-emitting portion; and a light-reflecting portion that comprises a one-dimensional or three-dimensional photonic crystal, is provided on an outer periphery of the light-passing portion, and reflects light to the inside of the light-passing portion.