Illumination device and liquid crystal display device

• US 8,310,621 B2
• Filed: 02/10/2009
• Issued: 11/13/2012
• Est. Priority Date: 02/13/2008
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Fujii, Akiyoshi, Azumada, Kyohko
• Primary Examiner(s): Stahl, Mike
• Application Number:
  US12/867,602
• Publication Number:
  US 20100321611A1
• Time in Patent Office: 1,372 Days
• Field of Search: None
• US Class Current: 349/61
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133548 Wire-grid polarisers
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials
• CPC Class Codes: G02F 2203/60 Temperature independent

Abstract

An illuminator according to the present invention includes a backlight (110) for emitting light containing first and second polarization components having polarization directions which are orthogonal to each other; and a selective reflection polarizer (120) having a reflectance for the first polarization component which is higher than a transmittance for the first polarization component, and having a transmittance for the second polarization component which is higher than a reflectance for the second polarization component. The selective reflection polarizer (120) includes a transparent substrate (122) and a plurality of metal wires (124) arrayed on the transparent substrate (122). The ratio of a width of the metal wires (124) to a pitch of the metal wires (124) is greater than 30% and equal to or less than 42%, and the backlight (110) has a reflectance of 0.6 or more.

Claims

1. An illuminator comprising:

a backlight for emitting light containing first and second polarization components having polarization directions which are orthogonal to each other; and

a selective reflection polarizer having a reflectance for the first polarization component which is higher than a transmittance for the first polarization component, and having a transmittance for the second polarization component which is higher than a reflectance for the second polarization component, wherein,

the selective reflection polarizer includes a transparent substrate and a plurality of metal wires arrayed on the transparent substrate; and

a ratio of a width of the metal wires to a pitch of the metal wires is greater than 30% and equal to or less than 42%, and the backlight has a reflectance of 0.6 or more.

2. The illuminator of claim 1, wherein the reflectance of the backlight is no more than 0.8.

3. The illuminator of claim 1, wherein the pitch of the metal wires is 200 nm or less.

4. The illuminator of claim 1, wherein the metal wires have a thickness of substantially 100 nm.

5. A liquid crystal display device comprising:

a liquid crystal panel;

a backlight for emitting light containing first and second polarization components having polarization directions which are orthogonal to each other; and

a selective reflection polarizer interposed between the liquid crystal panel and the backlight, the selective reflection polarizer having a reflectance for the first polarization component which is higher than a transmittance for the first polarization component, and having a transmittance for the second polarization component which is higher than a reflectance for the second polarization component, wherein,

the selective reflection polarizer includes a transparent substrate and a plurality of metal wires arrayed on the transparent substrate; and

a ratio of a width of the metal wires to a pitch of the metal wires is greater than 30% and equal to or less than 42%, and the backlight has a reflectance of 0.6 or more.