Optical device, light-condensing backlight system, and liquid crystal display
First Claim
1. An optical element, comprising:
- at least three laminated circular-polarization-type-reflection polarizers (a) whose wavelength bands for selective reflection of polarized light overlap one another;
a layer (b1) which is placed between at least a pair of the circular-polarization-type-reflection polarizers (a) and has a front retardation of substantially zero (in the normal direction) and a retardation of at least λ
/8 with respect to incident light inclined by at least 30°
relative to the normal direction; and
a layer (b2) which is placed between at least another pair of the circular-polarization-type-reflection polarizers (a) and has a front retardation of substantially zero (in the normal direction) and a retardation of at most λ
/2 with respect to incident light inclined by 60°
relative to the normal direction.
1 Assignment
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Accused Products
Abstract
An optical element of the invention comprises at least three laminated circular-polarization-type-reflection polarizers (a) whose wavelength bands for selective reflection of polarized light overlap one another; a layer (b1) which is placed between at least a pair of the circular-polarization-type-reflection polarizers (a) and has a front retardation of substantially zero (in the normal direction) and a retardation of at least λ/8 with respect to incident light inclined by at least 30° relative to the normal direction; and a layer (b2) which is placed between at least another pair of the circular-polarization-type-reflection polarizers (a) and has a front retardation of substantially zero (in the normal direction) and a retardation of at most μ/2 with respect to incident light inclined by 60° relative to the normal direction. The optical element condenses or collimates incident light from a light source and can control transmission of light at large incident angles relative to the normal direction, increase front brightness and reduce coloration.
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Citations
13 Claims
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1. An optical element, comprising:
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at least three laminated circular-polarization-type-reflection polarizers (a) whose wavelength bands for selective reflection of polarized light overlap one another;
a layer (b1) which is placed between at least a pair of the circular-polarization-type-reflection polarizers (a) and has a front retardation of substantially zero (in the normal direction) and a retardation of at least λ
/8 with respect to incident light inclined by at least 30°
relative to the normal direction; and
a layer (b2) which is placed between at least another pair of the circular-polarization-type-reflection polarizers (a) and has a front retardation of substantially zero (in the normal direction) and a retardation of at most λ
/2 with respect to incident light inclined by 60°
relative to the normal direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification