Upper side light diffuser sheet and backlight unit including the same

Patent metadata

Field	Value
Publication number	US-11287694-B2
Application number	US-201816619902-A
Country	US
Kind code	B2
Filing date	May 15, 2018
Priority date	Jun 6, 2017
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

An upper side light diffuser sheet includes a substrate layer, and a light diffusion layer overlaid on a front face side of the substrate layer. The light diffusion layer includes a resin matrix, and resin beads dispersed in the resin matrix. The resin beads include a first resin bead group having an average particle diameter D50 of 1.9 μm or more and 3.3 μm or less, and a second resin bead group having an average particle diameter D50 larger than the average particle diameter D50 of the first resin bead group. A mass ratio of the second resin bead group in an entire resin beads is 30% or more and 50% or less. A coating amount of the light diffusion layer is larger than 1.7 g/m 2 and smaller than 3.0 g/m 2 .

First claim

The invention claimed is:

1. An upper side light diffuser sheet to be disposed on a front face side of a prism sheet in a backlight unit of a liquid crystal display device, the upper side light diffuser sheet comprising:
a substrate layer, and a light diffusion layer overlaid on a front face side of the substrate layer, wherein
the light diffusion layer includes a resin matrix, and resin beads dispersed in the resin matrix;
the resin beads include a first resin bead group having an average particle diameter D50 of 1.9 μm or more and 3.3 μm or less, and a second resin bead group having an average particle diameter D50 larger than the average particle diameter D50 of the first resin bead group;
a mass ratio of the second resin bead group in an entirety of the resin beads is 30% or more and 50% or less;
a coating amount of the light diffusion layer is larger than 1.7 g/m 2 and smaller than 3.0 g/m 2 ; and
wherein the light diffusion layer has a minimum thickness in a region where the resin beads are not present in a thickness direction of greater than 0 and 1 μm or less.

2. The upper side light diffuser sheet according to claim 1 , wherein a mass content of the resin beads in the light diffusion layer is 41% or more and 45% or less.

3. The upper side light diffuser sheet according to claim 1 , wherein the second resin bead group has an average particle diameter D50 of 5.0 μm or more and 6.5 μm or less.

4. A backlight unit for a liquid crystal display device, the backlight unit comprising:
a light guide sheet that guides rays of light that enter from an end face to a front face side;
a light source that allows an end face of the light guide sheet to be irradiated with rays of light;
a lower side light diffuser sheet superposed on a front face side of the light guide sheet;
a prism sheet disposed on a front face side of the lower side light diffuser sheet; and
an upper side light diffuser sheet superposed on a front face side of the prism sheet,
wherein the upper side light diffuser sheet comprises:
a substrate layer, and a light diffusion layer overlaid on a front face side of the substrate layer, wherein
the light diffusion layer includes a resin matrix, and resin beads dispersed in the resin matrix;
the resin beads include a first resin bead group having an average particle diameter D50 of 1.9 μm or more and 3.3 μm or less, and a second resin bead group having an average particle diameter D50 larger than the average particle diameter D50 of the first resin bead group;
a mass ratio of the second resin bead group in an entirety of the resin beads is 30% or more and 50% or less;
a coating amount of the light diffusion layer is larger than 1.7 g/m 2 and smaller than 3.0 g/m 2 ; and
wherein the light diffusion layer has a minimum thickness in a region where the resin beads are not present in a thickness direction of greater than 0 and 1 μm or less.

Assignees

• Keiwa Inc

Inventors

• Nonaka Tadayuki
• Miyamoto Kana
• Maeda Hiroki

Classifications

• G02B5/02 Primary

  Diffusing elements; Afocal elements · CPC title

• G02F2202/36

  Micro- or nanomaterials · CPC title

• G02F1/133603

  with LEDs · CPC title

• G02F1/133607 Primary

  the light controlling member including light directing or refracting elements, e.g. prisms or lenses · CPC title

• G02F1/133504

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