Liquid crystal display device
View Patent ↗In a liquid crystal display device, a TFT substrate and a counter substrate are bonded by a sealing material, with a liquid crystal interposed between the two substrates. An alignment film has a two-layer structure of a lower alignment film not subjected to photo alignment treatment and an upper alignment film subjected to photo alignment treatment and contacting the liquid crystal. A hollow with an increased film thickness is formed in an end portion of the lower alignment film. An end portion of the upper alignment film is determined by the hollow of the lower alignment film. The material, process conditions, or other conditions of the lower alignment film for easy control of outer end dimensions can be selected to easily control the profile of the alignment film as a whole. Thus, it is possible to avoid the reduction of reliability due to the reduction of the bonding strength between the sealing material and the alignment film.
1. A liquid crystal display device comprising:
a TFT substrate including a display area with pixels arranged in a matrix form, each pixel including a pixel electrode and a TFT, in which an alignment film is formed;
a counter substrate disposed opposite the TFT substrate; and
a liquid crystal interposed between the TFT substrate and the counter substrate,
wherein the alignment film includes a lower alignment film and an upper alignment film that is stacked on the lower alignment film and contacts with the liquid crystal,
wherein the upper alignment film is subjected to photo alignment treatment,
wherein a material of the lower alignment film and a material of the upper alignment film are polyimide,
wherein a bulge with an increased film thickness is formed at an end portion of the lower alignment film, and
wherein an end portion of the upper alignment film is present on a side closer to the display area than the bulge of the lower alignment film.
2. The liquid crystal display device according to claim 1 , wherein the end portion of the lower alignment film is present between the display area and a sealing material.
3. The liquid crystal display device according to claim 1 , wherein the end portion of the lower alignment film is present between outer and inner ends of a sealing material.
4. The liquid crystal display device according to claim 1 , wherein the end portion of the lower alignment film is formed to an end portion of the TFT substrate or the counter substrate.
5. The liquid crystal display device according to claim 1 , wherein a film below the lower alignment film has a thinner portion, and
wherein the lower alignment film is formed on the thinner portion.
6. The liquid crystal display device according to claim 1 , wherein the lower alignment film does not contribute to the alignment of the liquid crystal.
7. A liquid crystal display device comprising:
a TFT substrate including a display area with pixels arranged in a matrix form, each pixel including a pixel electrode and a TFT, in which an alignment film is formed;
a counter substrate disposed opposite the TFT substrate; and
a liquid crystal interposed between the TFT substrate and the counter substrate,
wherein the alignment film includes a lower alignment film and an upper alignment film that is formed on the lower alignment film and contacts with the liquid crystal,
wherein the upper alignment film includes a first alignment film contacting the lower alignment film and a second alignment film contacting the liquid crystal,
wherein the second alignment film of the upper alignment film is not subjected to photo alignment treatment, and the first alignment film of the upper alignment film does not contribute to the alignment of the liquid crystal,
wherein the lower alignment film does not contribute to the alignment of the liquid crystal,
wherein a material of the lower alignment film and a material of the upper alignment film are polyimide,
wherein a bulge with an increased film thickness is formed at an end portion of the lower alignment film, and
wherein an end portion of the upper alignment film is determined by the bulge of the lower alignment film.
8. The liquid crystal display device according to claim 7 , wherein the material of the second alignment film of the upper alignment film has a concentration gradient in the film thickness direction of the upper alignment film.