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Double Layered Super Twisted Nematic LCD (D-STN) which can be operated by 1/128 duty ratio is presented. Two conflicting requirements; good visibility and a wide operating temperature range are fulfilled through optimization of cell parameters, such as twist angle, pretilt angle of liquid crystal to glass substrate and elastic properties of liquid crystal material. The response time of LCD decreases with increasing temperature. Hence at high temperature, the “frame response” phenomenon is observed and this results in reduction of contrast ratio. We propose multiple line selection (MLS) method for increasing in contrast ratio at high temperature.

A Double-Layered Super-Twisted Nematic (D-STN) LCD was developed for application in an automotive information display requiring the presentation of both character and symbolic information. Cell parameters were optimized to minimize the background transmission and to widen the operating temperature range. A contrast ratio exceeding 50:1 was achieved for temperature range of -30°C to 80°C. The viewing angle was found to be comparable to a conventional Twisted Nematic (TN) LCD multiplexed with a 1/2 duty cycle. Electro-optical properties, such as temperature dependence of the driving voltage and the response time have also been described.