Optical modulator and display device

Patent metadata

Field	Value
Publication number	US-10197856-B2
Application number	US-201615564179-A
Country	US
Kind code	B2
Filing date	Mar 28, 2016
Priority date	Apr 3, 2015
Publication date	Feb 5, 2019
Grant date	Feb 5, 2019

Abstract

The present invention provides an optical modulator that prevents aggregation of shape-anisotropic particles. The optical modulator of the present invention includes: (1) a first substrate and a second substrate that are disposed to face each other; (2) an optical modulation layer disposed between the first substrate and the second substrate; and (3) a vertical alignment film. The optical modulation layer (2) contains: (2A) liquid crystal molecules that have a positive anisotropy of dielectric constant with a value of the anisotropy Δε of 10 or more; and (2B) shape-anisotropic particles each including a core material and a coating layer that is formed of a material containing a fluorine atom and constitutes an outer surface of the shape-anisotropic particles. The first substrate includes a pair of electrodes. The liquid crystal molecules and the shape-anisotropic particles are aligned perpendicular to the first substrate with no voltage applied to the electrodes and are tilted parallel to the first substrate by a transverse electric field generated by application of voltage to the electrodes. The liquid crystal molecules have a surface energy in the range of 27 to 35 mN/m. The vertical alignment film has a surface energy in the range of 30 to 40 mN/m.

First claim

The invention claimed is:

1. An optical modulator, comprising:
a first substrate and a second substrate that are disposed to face each other;
an optical modulation layer disposed between the first substrate and the second substrate; and
a vertical alignment film disposed on an optical modulation layer side surface of at least one of the first substrate and the second substrate,
the optical modulation layer containing shape-anisotropic particles and liquid crystal molecules that have a positive anisotropy of dielectric constant with a value of the anisotropy Δε of 10 or more,
the shape-anisotropic particles each including a core material and a coating layer that is formed of a material containing a fluorine atom and constitutes an outer surface of the shape-anisotropic particles,
the first substrate including a pair of electrodes,
the liquid crystal molecules and the shape-anisotropic particles being aligned perpendicular to the first substrate with no voltage applied to the electrodes and being tilted parallel to the first substrate by a transverse electric field generated by application of voltage to the electrodes,
the liquid crystal molecules having a surface energy in the range of 27 to 35 mN/m,
the vertical alignment film having a surface energy in the range of 30 to 40 mN/m
wherein in a projected image on a surface of the first substrate, the shape-anisotropic particles are dispersed in the optical modulation layer at a density of 500 particles/4 mm 2 or higher.

2. The optical modulator according to claim 1 ,
wherein the shape-anisotropic particles each include an inorganic oxide layer between the core material and the coating layer.

3. The optical modulator according to claim 1 ,
wherein the coating layer contains a functional group containing fluorine.

4. The optical modulator according to claim 1 ,
wherein the pair of electrodes is a pair of comb electrodes whose comb teeth fit each other.

5. The optical modulator according to claim 1 ,
wherein the pair of electrodes is a combination of a planar electrode and an electrode including slits.

6. A display device comprising the optical modulator according to claim 1 .

7. The display device according to claim 6 ,
wherein the display device, with the transverse electric field generated, provides display by utilizing the shape-anisotropic particles to reflect external light.

8. The display device according to claim 7 ,
wherein one of the first substrate and the second substrate disposed on the back surface side includes a light-absorbing layer.

Assignees

• Sharp Kk

Inventors

• Ohtake Tadashi
• Teranishi Tomoko
• Moriwaki Hiroyuki
• Satoh Eiji
• Li Hao

Classifications

• G02F1/137

  characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering · CPC title

• G02F1/1343

  Electrodes {(reflective electrodes G02F1/133553)} · CPC title

• G02F2001/133742

  Physics · mapped topic

• G02F1/13725 Primary

  based on guest-host interaction (G02F1/13762, G02F1/13737, take precedence) · CPC title

• G02F1/17

  based on variable-absorption elements not provided for in groups G02F1/015 - G02F1/169 · CPC title