| 摘要 |
A backlight unit is provided to make the angular distribution of light emitted through an emission face of a light guiding plate uniform, thereby improving the display quality of an LCD(Liquid Crystal Display), by using a hologram element to include a two-dimensional diffraction pattern formed on the light guiding plate. A backlight unit comprises at least one point light source(40) for emitting light, a light guiding plate(42), and a hologram element(43). The light guiding plate has an incidence face(42b), on which the light emitted from the point light source is incident, and an emission face(42a) facing an LCD panel. The light guiding plate guides the incident light to the emission face. The hologram element includes a first diffraction pattern for diffracting the incident light in a direction vertical to the incidence face, and a second diffraction pattern for diffracting the incident light in a direction parallel to the incidence face or within a range of 10 degrees with respect to the incidence face. The first and second diffraction patterns are formed in a matrix type on at least one of the emission face of the light guiding plate and the back face of the emission face. |
