| 摘要 |
PROBLEM TO BE SOLVED: To obtain the polarized light separation and conversion type polarizing element which converts natural light into linear polarized light with high efficiency by forming a periodic structure reflection increasing film on resin as design and to provide a liquid crystal display device which has high luminance or saves the power consumption by using the polarizing element. SOLUTION: A sheet type prism array which has right-angled triangular prisms arranged in array consists of periodic structure reflection increasing films 2 formed of gas barrier films and low-refractive-index and high-refractive-index thin films on the slanting surfaces of the triangular prisms and 1/2-wavelength plates 4 formed on the perpendicular surfaces of the right-angled prisms; and incident light is polarized and separated by a reflection increase film 2 and its reflected light consists of a p- polarized component and is polarized and converted by a 1/2-wavelength plate 4, totally reflected by an adjacent prism slanting surface, and projected out of the element almost vertically. The refracted light contains p- and s-polarized components at nearly the same rate and is projected out of a prism. Those reflected light and refracted light are passed through a polarizing plate 5 to obtain only the p-polarized light, so that >=50% of p-polarized light is obtained from the incident natural light. Namely, >=50% transmissivity can be obtained and can be increased almost to 90% depending upon the design of the reflection increasing films. |
