A backlight module (3) includes a light source group (31) and a light guide plate (32). The light source group includes at least a light source, and the light guide plate has a light input surface (321) for receiving light, a light output surface (322) for emitting light, which is adjacent to the light input surface, and a bottom surface opposite to the light output surface and adjacent the light input surface. The light source group faces the light input surface, which is curved such that its curvature matches with the light distribution of the light source group.

A multifunctional-type backlight unit, including a light guiding plate having a first incident/exit surface and a second incident/exit surface which are capable of receiving and emitting light, a light emitting device disposed to face the first incident/exit surface and configured to supply light to the first incident/exit surface, and a light receiving device disposed to face the first incident/exit surface and configured to receive light emitted from the first incident/exit surface, the light guiding plate being configured so that the light emitted from the light emitting device enters the light guiding plate, passes through the light guiding plate, and is emitted from the second incident/exit surface, and the light guiding plate being configured so that the light which enters the second incident/exit surface, passes through the light guiding plate emits from the first incident/exit surface is received by the light receiving device.

A lighting apparatus for causing the light from a light source to enter the incident surface of a light guide plate and to project the light toward an object of illumination from the exit surface of the light guide plate extending in the direction perpendicular to the incident surface. The light source is made by placing a light-emitting diode on or near the light source rod extending in the longitudinal direction parallel to the incident surface of the light guide plate. The light source rod and the light guide plate are integrally made by forming a slot in a common plate.

A backlight unit includes a light guide panel where a holographic pattern is formed. A point light source emits light to an edge of the light guide panel. A refractive member is provided between the point light source and the light guide panel and reduces an azimuth angle of light incident on the light guide panel. The refractive member includes, from an optical axis of the point light source, a light transmission zone transmitting light as it is, a blaze zone where a blaze pattern having a saw-toothed shape in which one surface near the optical axis and substantially parallel to the optical axis is formed, and a prism zone where a triangular prism pattern is formed. The backlight unit may further include a diffusive member diffusing light emitted from the point light source to be incident on the refractive member.

A light guide plate (30) has a light incident surface (305) for receiving light, a light emitting surface (301) for emitting light, a bottom surface (303) opposite to the light emitting surface, and side surfaces (307, 309, 311). A subwavelength grating (302) is formed on the light incident surface for diffracting the light. The subwavelength grating is a zeroth-order grating which covers a wide wavelength band and diffracts the light into zeroth-order waves. So that the light guide plate has a high light utilization efficiency and yields high uniformity of outgoing light.