| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a backlight unit, or the like, by which a relatively high degree of white light is formed even if a diffraction grating is included in a light guide plate. <P>SOLUTION: On the top face 11U of the light guide plate 11, the top face diffraction grating DGU is formed by which one of light to reach thereat with an incident angle of a specific range is diffracted and transmitted to the outside thereof while being raised with respect to the top face 11U, and one of the residual light is diffracted and reflected to the top face 11U. Moreover, on the bottom face 11B of the light guide plate 11, the bottom face diffraction grating DGB is formed, which includes three groups of grating pieces 13 arranged at cycles different from each other. Then, three grating piece groups 13gr.B, 13gr.G, 13gr.R correspond to the light in mutually different wavelength regions, and respective grating piece groups 13gr.B, 13gr.G, 13gr.R diffract and reflect only the incident light, with the incident angle which has a specific range through the use of the light in the corresponding specific wavelength region so as to return it to its light traveling side. <P>COPYRIGHT: (C)2010,JPO&INPIT |
