Liquid crystal display and method for manufacturing same
View Patent ↗A liquid crystal display is provided which is capable of reducing the occurrence of defective display due to variations in the initial alignment direction of a liquid crystal alignment control film in a liquid crystal display of an IPS scheme, realizing the stable liquid crystal alignment, providing excellent mass productivity, and having high image quality with a higher contrast ratio. The liquid crystal display has a liquid crystal layer disposed between a pair of substrates, at least one of the substrates being transparent, and an alignment control film formed between the liquid crystal layer and the substrate. At least one of the alignment control films 109 comprises photoreactive polyimide and/or polyamic acid provided with an alignment control ability by irradiation of substantially linearly polarized light.
1. A liquid crystal display comprising:
a pair of substrates, at least one of said substrates being transparent;
a liquid crystal layer disposed between said pair of substrates;
a group of electrodes formed on one of said pair of substrates for applying an electric field having a component substantially in parallel with a surface of said substrate to said liquid crystal layer;
an alignment control film disposed between said liquid crystal layer and at least one of said pair of substrates; and
optical means formed on at least one of said pair of substrates, for changing an optical property of said liquid crystal layer in accordance with an alignment state of molecules of said liquid crystal layer,
wherein at least one of said alignment control films is an alignment control film consisting of photoreactive polyimide and/or polyamic acid provided with an alignment control ability by irradiation of substantially linearly polarized light, and
wherein an anchoring energy in the azimuth direction at an interface of the alignment control film and the liquid crystal layer is 2.3×10 −4 N/m or more.
2. The liquid crystal display according to claim 1 , wherein the anchoring energy in the azimuth direction at an interface of the alignment control film and the liquid crystal layer is 6.0×10 −4 N/m or more.
3. The liquid crystal display according to claim 1 , wherein the anchoring energy in the azimuth direction at an interface of the alignment control film and the liquid crystal layer is 1.0×10 −3 N/m or more.
4. The liquid crystal display according to claim 1 , wherein an alignment direction of the liquid crystal molecules of the liquid crystal layer on a surface of said alignment control film is in parallel with or orthogonal to a polarization axis of the substantially linearly polarized light for irradiation.
5. The liquid crystal display according to claim 1 , wherein said alignment control film consisting of the polyimide and/or polyamic acid material has a thickness from 1 nm to 100 nm.
6. The liquid crystal display according to claim 1 , wherein said alignment control film has a thickness from 1 nm to 50 nm above the electrodes constituting said group of electrodes.
7. The liquid crystal display according to claim 1 , wherein said alignment control film has a thickness from 1 nm to 30 nm above the electrodes constituting said group of electrodes.
8. The liquid crystal display according to claim 1 , wherein the alignment control film has a glass transition temperature equal to or higher than 250° C.
9. The liquid crystal display according to claim 1 , wherein said liquid crystal layer has a pretilt angle equal to or smaller than one degree.
10. The liquid crystal display according to claim 1 , wherein said group of electrodes has a pixel electrode and a common electrode, and at least one of the pixel electrode and the common electrode is formed of a transparent electrode.
11. The liquid crystal display according to claim 1 , wherein the transparent electrode is formed of an ion-doped titanium oxide film or an ion-doped zinc oxide film.
12. The liquid crystal display according to claim 1 , wherein said liquid crystal molecules have substantially the same alignment control directions at two interfaces between said liquid crystal layer and said alignment control film formed on the at least one of said pair of substrates.