A liquid crystal display device of stable color tone uses phase difference plates made of a uniaxially stretched polymer film and comprises a polarizer plate, a first phase difference plate, a second phase difference plate, a supertwisted nematic type liquid crystal display panel, and a polarizer plate...http://www.google.es/patents/US5493431?utm_source=gb-gplus-sharePatente US5493431 - Liquid crystal display device with compensators
