| 摘要 |
PURPOSE:To provide a back light with high power consumption-luminance conversion efficiency and with high luminance by making at least a part of a light reflection surface a continuous body with a shape where a light beam tangentially outgoing from a light emitting point of a bar-shaped light source to a side far from a light transmission plate in the direction perpendicular to the longitudinal central axis of the bar-shaped light source is reflected to the light emitting point. CONSTITUTION:This back light is constituted of the light transmission plate 1 made of translucent material and provided with a light diffusion action and/or a light scattering action, the bar-shaped light source 4 arranged close to at least one side surface end part of the light transmission plate 1 and the light reflection surface 7 covering the light source 4. At least a part of the light reflection surface 7 is constituted so as to be the continuous body 7a with the shape where the light beam tangentially outgoing from the light emitting point of the bar-shaped light source 4 to the side far from the light transmission plate 1 in the direction perpendicular to the longitudinal central axis of the bar-shaped light source is reflected to the light emitting point. That is, the continuous body 7a of the light reflection body is made to much with an involute of a curve smoothly linking plural light emitting points of the bar-shaped light source 4 substantially. |
