| 摘要 |
PURPOSE:To thin a back light and prevent light leakage by making the opening width of a reflecting cover almost the same with the thickness of a light diffusing plate end face, in a structure wherein light is made incident from the side face of the diffusing plate having a reflecting face on its bottom and radiated out of the face opposite to the reflecting face. CONSTITUTION:LED light R emitted out of a LED element 4 goes straight or is reflected on a reflecting sheet 11 or a reflecting end face 1a to be incident upon a diffusing plate 12. The light R is repeatedly reflected between the inner face of a radiating face 18 and a diffusing face 13, which is the bottom of the diffusing plate and the light reaches the radiating face 18 at critical angle or more is radiated to the outside. In this case, a gradation pattern is formed in the diffusing face 13 due to a large number of projected parts formed more densely as the distance from the element 4 is larger and the light is diffused and reflected efficiently and at the same time the brightness of the light R is made uniform. With this structure, since the width X of the opening part of a reflecting cover 1 in the light emitting part and the thickness (t) of the diffusing plate 12 are set almost equal to each other, the gap between them is eliminated to thin the structure and the light R is prevented from leaking outside. |
