Optical member

• US 10,302,994 B2
• Filed: 08/17/2017
• Issued: 05/28/2019
• Est. Priority Date: 09/02/2016
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Nakamura, Kozo, Hattori, Daisuke, Hosokawa, Kazuhito
• Primary Examiner(s): Shafer, Ricky D
• Application Number:
  US15/679,436
• Publication Number:
  US 20180067360A1
• Time in Patent Office: 649 Days
• Field of Search: 35948501, 35948702, 35948907, 35948908, 35948911, 35948912, 359599
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/1335 Structural association of cells with optical devices, e.g. polarisers or reflectors
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133567 on the back side
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 2413/01 Number of plates being 1
• CPC Class Codes: G02F 2413/05 Single plate on one side of the LC cell

Abstract

There is provided an optical member capable of causing, when used for a liquid crystal display apparatus, light output from a light source to enter a liquid crystal display panel with high efficiency. An optical member according to an embodiment of the present invention includes: a polarizing plate; a reflective polarizer; a polarization converting layer; and a prism layer, the polarizing plate, the reflective polarizer, the polarization converting layer, and the prism layer being integrated in the stated order, wherein the polarization converting layer satisfies the following expression: L₉₀/L₀≥0.2.

Claims

1. An optical member, comprising:

a polarizing plate;

a reflective polarizer;

a polarization converting layer; and

a prism layer,

the polarizing plate, the reflective polarizer, the polarization converting layer, and the prism layer being integrated in the stated order,

wherein the polarization converting layer satisfies the following expression;

L₉₀/L₀≥

0.2

where, with regard to a luminance of natural light transmitted through a first polarizer and a second polarizer each having a polarization degree of 99.99%,

L₀ represents a parallel luminance, which is the luminance when the polarization converting layer is arranged between the first polarizer and the second polarizer arranged so that absorption axes thereof are parallel to each other, and

L₉₀ represents a perpendicular luminance, which is the luminance when the polarization converting layer is arranged between the first polarizer and the second polarizer arranged so that the absorption axes thereof are perpendicular to each other.

2. The optical member according to claim 1,

wherein the polarization converting layer comprises a retardation layer, and

wherein the retardation layer has an in-plane retardation Re(550) of 3,500 nm or more, where Re(550) represents an in-plane retardation measured with light having a wavelength of 550 nm at 23°

C.

3. The optical member according to claim 1,

wherein the polarization converting layer comprises a light diffusing layer, and

wherein the light diffusing layer has a haze value of from 80% to 99.9%.

4. The optical member according to claim 1,

wherein the polarization converting layer comprises a λ

/4 plate,

wherein the λ

/4 plate has an in-plane retardation Re(550) of from 80 nm to 200 nm, and

wherein an angle formed between a slow axis of the λ

/4 plate and a reflection axis of the reflective polarizer is from 30°

to 60°

.

5. The optical member according to claim 1, further comprising a low-refractive index layer integrated at one of a position between the reflective polarizer and the prism layer, and a position on an opposite side of the reflective polarizer to the prism layer, wherein the low-refractive index layer has a refractive index of 1.30 or less.

6. The optical member according to claim 1, wherein the reflective polarizer comprises a linearly polarized light separation-type reflective polarizer.