Liquid crystal display device

Patent metadata

Field	Value
Publication number	US-9250475-B2
Application number	US-201113880511-A
Country	US
Kind code	B2
Filing date	Oct 17, 2011
Priority date	Oct 21, 2010
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

A liquid crystal display device ( 100 A) of the present invention includes a liquid crystal layer ( 1 ) and first and second alignment films ( 12, 13 ) which are provided with an alignment treatment. The liquid crystal layer ( 1 ) includes, in each of the pixels, a plurality of first small sections ( 14 a ) separated by a wall ( 10 ) and the first alignment film ( 12 ) and a plurality of second small sections ( 14 b ) separated by the wall ( 10 ) and the second alignment film ( 13 ). Each of the plurality of first small sections ( 14 a ) has a first liquid crystal region ( 11 a ). Each of the plurality of second small sections ( 14 b ) has a second liquid crystal region ( 11 b ). Each of the first and second liquid crystal regions ( 11 a , 11 b ) includes a nematic liquid crystal material and a dichromatic dye ( 21 a , 21 b ). The dichromatic dye ( 21 a ) of the first liquid crystal region ( 11 a ) is aligned along the alignment direction of the first alignment film ( 12 ). The dichromatic dye ( 21 b ) of the second liquid crystal region ( 11 b ) is aligned along the alignment direction of the second alignment film ( 13 ).

First claim

The invention claimed is:

1. A liquid crystal display device having pixels, comprising:
a liquid crystal layer whose state is switchable between a light-transmitting state in which light is transmitted through the liquid crystal layer and a light-scattering state in which light is scattered by the liquid crystal layer;
a first substrate and a second substrate between which the liquid crystal layer is held;
a pair of electrodes between which the liquid crystal layer is interposed and which are configured to apply a voltage across the liquid crystal layer; and
first and second alignment films respectively provided between the liquid crystal layer and the first substrate and between the liquid crystal layer and the second substrate, the first and second alignment films being provided with an alignment treatment,
wherein the liquid crystal layer includes, in the pixels,
a continuous wall,
a plurality of first small sections separated by the wall and the first alignment film, and
a plurality of second small sections separated by the wall and the second alignment film,

each of the plurality of first small sections has a first liquid crystal region,
each of the plurality of second small sections has a second liquid crystal region,
each of the first and second liquid crystal regions includes a nematic liquid crystal material and a dichromatic dye,
the nematic liquid crystal material and the dichromatic dye in the first liquid crystal region are in contact with the first alignment film, and the nematic liquid crystal material and the dichromatic dye in the second liquid crystal region are in contact with the second alignment film,
the liquid crystal layer does not include a small section separated only by the wall,
the dichromatic dye of the first liquid crystal region is aligned along a first azimuth which is defined by the first alignment film, and
the dichromatic dye of the second liquid crystal region is aligned along a second azimuth which is defined by the second alignment film.

2. The liquid crystal display device of claim 1 , wherein the first azimuth and the second azimuth are perpendicular to each other.

3. The liquid crystal display device of claim 1 , wherein the first and second liquid crystal regions do not contain a chiral agent.

4. The liquid crystal display device of claim 1 , wherein the liquid crystal layer includes the plurality of first and second small sections at a density of 0.064 sections/μm 2 or higher.

5. The liquid crystal display device of claim 4 , wherein the liquid crystal layer includes the plurality of first and second small sections at a density of 1 section/μm 2 or higher.

6. The liquid crystal display device of claim 1 , wherein a maximum width of each of the plurality of first and second small sections is not less than 0.6 μm and not more than 6 μm.

7. The liquid crystal display device of claim 1 , wherein a difference between an extraordinary refractive index ne and an ordinary refractive index no of the nematic liquid crystal material included in the first and second liquid crystal regions is not less than 0.1 and not more than 0.3.

8. The liquid crystal display device of claim 1 , further comprising a plurality of third and fourth small sections which are separated by the wall, wherein
the plurality of third small sections are present in the vicinity of the first alignment film and each have a third liquid crystal region,
the plurality of fourth small sections are present in the vicinity of the second alignment film and each have a fourth liquid crystal region,
each of the third and fourth liquid crystal regions includes the nematic liquid crystal material and the dichromatic dye,
the dichromatic dye of the third liquid crystal region is aligned along the first azimuth, and
the dichromatic dye of the fourth liquid crystal region is aligned along the second azimuth.

9. The liquid crystal display device of claim 1 , wherein a surface free energy of the first and second alignment films is not less than 44 mJ/m 2 and not more than 50 mJ/m 2 .

10. The liquid crystal display device of claim 1 , wherein a dielectric anisotropy of the nematic liquid crystal material is positive.

11. The liquid crystal display device of claim 1 , wherein each of the pair of electrodes which are configured to apply a voltage across the liquid crystal layer is a transparent electrode.

12. The liquid crystal display device of claim 1 , wherein any one of the pair of electrodes which are configured to apply a voltage across the liquid crystal layer is a reflective electrode.

13. The liquid crystal display device of claim 1 , wherein any one of the pair of electrodes which are configured to apply a voltage across the liquid crystal layer is a scatter reflection electrode.

14. The liquid crystal display device of claim 13 , wherein
a surface of the scatter reflection electrode has unevenness, and
a difference between a highest portion and a lowest portion of the surface of the scatter reflection electrode which is attributed to the unevenness is not less than 100 nm and not more than 500 nm.

15. The liquid crystal display device of claim 14 , further comprising
an active element which is provided on the first substrate and which is provided in each of the pixels, the active element having a memory property,
a wire which is provided on the first substrate, and
an interlayer insulating film which is provided on the active element and the wire,
wherein the scatter reflection electrode is provided on the interlayer insulating film, and
when measuring an intensity of reflection by the scatter reflection electrode of light which is incident on the scatter reflection electrode from a direction of −30° with respect to a normal direction of the scatter reflection electrode where a clockwise direction is a positive direction and a counterclockwise direction is a negative direction, 0.02<I(35°)/I(30°)<0.1 holds true (where)I(θ°) is an intensity of reflection which is measured in a direction of θ° with respect to the normal direction of the scatter reflection electrode).

16. The liquid crystal display device of claim 15 , wherein I(40°)/I(30°)<0.02 also holds true.

17. The liquid crystal display device of claim 15 , wherein a region in which the active element and the wire are provided occupies ⅓ or more of an area of the pixel.

18. The liquid crystal display device of claim 15 , wherein a portion of the interlayer insulating film extending over a region in which none of the active element and the wire is provided has unevenness which is formed by patterning the portion.

19. The liquid crystal display device of claim 15 , wherein a thickness of the interlayer insulating film is not less than 1.5 μm and not more than 3.5 μm.

20. The liquid crystal display device of claim 1 , wherein the dichromatic dye is a dichromatic fluorescent dye.

Assignees

• Asaoka Yasushi
• Minoura Kiyoshi
• Satoh Eiji
• Fujiwara Sayuri
• Sharp Kk

Inventors

• Asaoka Yasushi
• Minoura Kiyoshi
• Satoh Eiji
• Fujiwara Sayuri

Classifications

• G02F1/1337 Primary

  Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers · CPC title

• G02F1/133553

  Reflecting elements (associated to illuminating devices G02F1/133605) · CPC title

• G02F1/13725

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

• G02F2001/133773

  Physics · mapped topic

• G02F1/1334

  based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals · CPC title