Wire grid polarizer and liquid crystal display device using the same

• US 7,894,019 B2
• Filed: 04/23/2008
• Issued: 02/22/2011
• Est. Priority Date: 10/17/2005
• Status: Active Grant

• Current Assignee: Asahi Kasei Kabushiki Kaisha (Asahi Kasei Corporation)
• Original Assignee: Asahi Kasei Kabushiki Kaisha (Asahi Kasei Corporation)
• Inventors: Yamaki, Hiroshi, Kawazu, Yasuyuki, Sato, Yusuke, Namatame, Takuji
• Primary Examiner(s): Pak; Sung H
• Application Number:
  US12/081,900
• Publication Number:
  US 20080303986A1
• Time in Patent Office: 1,035 Days
• Field of Search: None
• US Class Current: 349/96
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133548 Wire-grid polarisers

Abstract

A wire grid polarizer has mainly a resin substrate 1 having grid-shaped convex portions 1a, a dielectric layer 2 provided to cover the grid-shaped convex portions 1a of the resin substrate 1 and at least part of side faces 1b of the portions, and metal wires 3 provided on the dielectric layer. The wire grid polarizer has a microstructural concavo-convex grid structure having grid-shaped convex portions, is not limited in structure, and has both the excellent degree of polarization and excellent transmittance over a wide range in the visible region.

Claims

1. A thin polarizer having:

a thickness of 80 μ

m or less;

a degree of polarization of 99.9% or more;

a transmittance of 35% or more; and

a reflectance of 30% or more.

2. The thin polarizer according to claim 1, wherein the polarizer is formed of:

a substrate having grid-shaped convex portions on its surface;

a dielectric layer provided on a region including the grid-shaped convex portions; and

metal wires provided on the dielectric layer.

3. The thin polarizer according to claim 2, wherein the polarizer comprises:

a resin substrate having grid-shaped convex portions;

a dielectric layer provided to cover the grid-shaped convex portions of the resin substrate and at least part of side faces of the portions; and

metal wires of which top portions are positioned higher than the convex portions of the dielectric layer.

4. The thin polarizer according to claim 2 or 3, wherein the metal wires are deposited leaning to one side faces of the convex portions of the dielectric layer.

5. The thin polarizer according to claim 2 or 3, wherein a height difference H₂ ranges from 100 nm to 300 nm, the height difference H₂ between a convex-portion peak and a concave-portion valley of a concavo-convex grid formed by covering the grid-shaped convex portions of the resin substrate with the dielectric.

6. The thin polarizer according to claim 2 or 3, wherein pitches of the grid-shaped convex portions of the resin substrate are 150 nm or less, and heights thereof are 0.5 time to 2 times the pitches.

7. The thin polarizer according to claim 2 or 3, wherein the polarizer is a wire grid polarizer comprising:

a resin substrate having grid-shaped convex portions;

a dielectric layer provided to cover the grid-shaped convex portions of the resin substrate and at least part of side faces of the portions; and

metal wires provided on the dielectric layer, and as a cross-sectional shape of the convex portions of a concavo-convex grid formed by covering the grid-shaped convex portions of the resin substrate with the dielectric, in a plane intersecting perpendicularly a longitudinal direction of the grid, a concave portion is substantially in the shape of a parabola, and wH/wL ranges from 0.3 to 0.9, the wH/wL being a ratio of a convex-portion width wH at a height two-thirds a height of a convex portion from a bottom to a convex-portion width wL at a height one-third the height of the convex portion from the bottom.

8. The thin polarizer according to claim 2 or 3, wherein a height difference H₂ ranges from 100 nm to 300 nm, the height difference H₂ between a convex-portion peak and a concave-portion valley of a concavo-convex grid formed by covering the grid-shaped convex portions of the resin substrate with the dielectric.

9. The thin polarizer according to claim 2 or 3, wherein a width w₂ at a height half a height difference H₂ is 0.1 time to 0.5 time pitches of the grid-shaped convex portions of the resin substrate, the height difference H₂ between a convex-portion peak and a concave-portion valley of a concavo-convex grid formed by covering the grid-shaped convex portions of the resin substrate with the dielectric.

10. The thin polarizer according to claim 2 or 3, wherein the metal wires are formed upward from slanting side faces of the convex portions of a concavo-convex grid formed by covering the grid-shaped convex portions of the resin substrate with the dielectric.