Optical stack and liquid crystal display apparatus

Patent metadata

Field	Value
Publication number	US-11860464-B2
Application number	US-202017599487-A
Country	US
Kind code	B2
Filing date	Mar 27, 2020
Priority date	Mar 28, 2019
Publication date	Jan 2, 2024
Grant date	Jan 2, 2024

Abstract

An optical stack includes: a light scattering film converting light received at a light receiving surface into scattering light therein and then outputting the scattering light outside from a light output surface, and a sheet provided on the light output surface side of the light scattering film. The light scattering film includes: a functional layer formed of a light-transmissive composition including an organic polymer compound and light scattering particles. The functional layer includes a first surface receiving the light and a second surface from which the scattering light is output. The functional layer includes a particle layer formed of light scattering particles having a content of 60% by volume or higher among the light scattering particles, the particle layer expanding along the first surface and being concentrated in a direction perpendicular to the first surface.

First claim

The invention claimed is:

1. An optical stack comprising:
a light scattering film converting light received at a light receiving surface into scattering light therein and then outputting the scattering light from a light output surface; and
a sheet provided on a light output surface side of the light scattering film, wherein
the light scattering film comprises:
a functional layer formed of a light-transmissive composition including an organic polymer compound and light scattering particles,

wherein the functional layer comprises a first surface receiving the light and a second surface from which the scattering light is output,
wherein the light scattering particles have an average particle size of 1.5 μm or larger,
wherein the functional layer further comprises a particle layer formed of light scattering particles having a content of 60% by volume or higher among the light scattering particles, the particle layer expanding along the first surface and being concentrated in a direction perpendicular to the first surface,
wherein the light scattering film is structured such that in a case that light having a normalized luminance of 0.5 or higher is incident on the first surface at an angle of incidence in a range of −32° to +32° with respect to the first surface, light having a normalized luminance of 0.33, among light to be output from the second surface, is output from the second surface at an angle of output in a range of −60° to −35° or +35° to +60° with respect to the second surface.

2. The optical stack of claim 1 , wherein a fraction of the light scattering particles, that have a particle size of 1.5 μm or larger and 4.5 μm or smaller, has a content of 60% by volume or higher and 96% by volume or lower with respect to an entirety of the light scattering particles included in the functional layer.

3. The optical stack of claim 1 , wherein a fraction of the light scattering particles, that have a particle size of 0.1 μm or larger and smaller than 1.5 μm, has a content of 4% by volume or higher and 40% by volume or lower with respect to an entirety of the light scattering particles included in the functional layer.

4. The optical stack of claim 1 , wherein the light scattering film has a thickness of 4 μm or more and 220 μm or less.

5. The optical stack of claim 1 , wherein the light scattering particles included in the functional layer corresponding to 1 m 2 of the first surface has a total volume of 4.5×10 −7 m 3 larger and 3.6×10 −6 m 3 or smaller.

6. The optical stack of claim 1 , wherein the light scattering particles are formed of at least one material selected from a group consisting of alumina, melamine resin, and hollow silica.

7. The optical stack of claim 6 , wherein the organic polymer compound is at least one selected from a group consisting of polymethylmethacrylate, polyvinylalcohol, polyvinylchloride, polycarbonate, polyethylene, polystyrene, polyamide, silicone, urea, epoxy, polypropylene, cellulose acetate, and polyvinylidenechloride.

8. The optical stack of claim 1 , wherein a refractive index of the light scattering particles and a refractive index of the organic polymer compound have a difference of 0.15 or larger and 1.0 or smaller.

9. The optical stack of claim 1 , wherein the light scattering film is formed of the functional layer scattering light isotropically.

10. The optical stack of claim 9 , wherein the sheet comprises a polarizing plate including a dye layer containing a dye in an oriented state, and
wherein the functional layer is directly bonded to the dye layer.

11. A liquid crystal display apparatus, comprising:
a light-condensing backlight unit;
a liquid crystal panel transmitting light from the light-condensing backlight unit; and
the optical stack of claim 1 ,
wherein the light-condensing backlight unit is structured such that light having a normalized luminance of 0.5 or higher, among the light to be incident on the liquid crystal panel, is incident at an angle of incidence in a range of 32° or smaller with respect to the liquid crystal panel, and
wherein the light scattering film is further structured such that the light from the light-condensing backlight unit is transmitted from the first surface toward the second surface of the functional layer.

12. The liquid crystal display apparatus of claim 11 ,
wherein the light scattering film further comprises a substrate bonded to the liquid crystal panel, and
wherein the substrate is a light-transmissive film formed of a polymer having high birefringence.

13. The liquid crystal display apparatus of claim 11 ,
wherein the sheet includes a transmitted light selecting layer preventing transmission of light in a specific wavelength range included in the light from the liquid crystal panel.

14. The liquid crystal display apparatus of claim 11 , wherein no component that scatters light anisotropically is provided closer to a viewer than the liquid crystal panel.

Assignees

• Sakai Display Products Corp

Inventors

• Yamada Shintaro
• Yoshida Yukio
• Maeda Atsuko
• Hombo Sumire
• Nakagawa Hideki
• Takeba Mitsuhiro
• Yamashita Toshihiro
• Kondo Katsumi

Classifications

• G02F1/133504 Primary

  Diffusing, scattering, diffracting elements (associated to illuminating devices G02F1/133606) · CPC title

• G02F1/133514

  Colour filters · CPC title

• G02F1/133528

  Polarisers · CPC title

• G02F2202/04

  dye · CPC title

• G02F2203/03

  scattering · CPC title