Liquid crystal display device

A liquid crystal display device comprising a TFT substrate in which an alignment film is formed on a pixel comprising a pixel electrode, a common electrode and a TFT, a counter substrate opposed to the TFT substrate in which an alignment film is formed on a color filter, and liquid crystals put between the alignment film of the TFT substrate and the alignment film of the counter substrate,

• wherein the alignment film of the TFT substrate is formed directly either on the pixel electrode or on the common electrode,
• wherein an alignment film of the TFT substrate and the alignment film of the counter substrate includes a polyamide acid ester having a structure of the chemical formula (1), the liquid crystals contain an antioxidant within a range from 0.0005 to 10 wt %, and a dielectric constant anisotropy of the liquid crystals is positive and is 5 or less,
• wherein a specific resistivity of the liquid crystals is 1014 Ωcm or higher,
• wherein the alignment film of the TFT substrate and the alignment film of the counter substrate includes the polyamide acid ester as a precursor,
• wherein the device is a liquid crystal display device of an IPS system in which a common electrode opposed to the pixel electrode is formed to the TFT substrate,
• wherein black unevenness attributable to impurities in the liquid crystal and DC image retention attributable to impurities at the boundary of the alignment film are reduced,
• wherein the alignment film of the TFT substrate and the alignment film of the counter substrate is aligned by optical alignment:
• where R1 represents each independently an alkyl group having 1 to 8 carbon atoms, R2 represents each independently a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a phenyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a vinyl group (—(CH2)m—CH≡CH2, m=0, 1, 2) or an acetyl group (—(CH2)m—C≡CH, m=0, 1, 2) and Ar represents an aromatic compound.