| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve an LED backlight for a liquid crystal panel which is expensive with high power consumption and large thickness, thereby obtaining the LED backlight that is thin at low cost with low power consumption and high luminance. <P>SOLUTION: A triangle pole prism has a cross-section of an isosceles triangle, and two equal angles of the isosceles triangle are equal to or more than 50° and less than 55°, and one of these two equal angles is an apex angle. In a downwardly arranged prism sheet where a large number of the triangle pole prisms are arranged, a parallelly-controlled light is made incident from a direction vertical to a surface of a small area at the slope of the triangle pole prism with an incidence angle of 10-24° from a horizontal surface of the prism sheet. In a surface of a large area at the slope of the triangle pole prism, the incident light is totally reflected and emitted to a direction vertical to the bottom of the triangle pole prism. The light, which is obtained by using the optical system for the backlight of the liquid crystal display device, and which penetrates the liquid crystal panel and two orthogonally arranged polarizing plates, is spread by using an anisotropic diffuser with a function for spreading light in the direction orthogonal to a triangle pole of the triangle pole prism sheet. <P>COPYRIGHT: (C)2008,JPO&INPIT |
