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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.

The basic principles and characteristics of VHC (Very High Contrast) LCD technology have previously been introduced and presented. In this paper practical automotive display applications such as a primary instrument display (direct view display), HUD (Head-up display) and virtual image display utilizing this VHC technology are described. Through material development and optical optimization, a highly reflective instrument display, even in a blue-green color was acheived.As well, a high reliability HUD was developed.

The relation between device parameters and characteristics of VHC (Very High Contrast) LCD are described. In order to obtain high contrast ratio and wide viewing angle, the following parameters must be considered. cell gap optical anisotropy of liquid crystal material precise directions of polarization axes twist angle of liquid crystal The optimization of these parameters enabled the development of a VHC LCD which can be set obliquely in a dashboard to prevent surface reflections of the sun light. In this case, retardation of the support films of the polarizers must be taken into account. With control of the retardation, the driving voltage of the cell was reduced.