Grey level control by variation of the surface interaction in AFLCD's

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Abstract
We report the influence of the rubbing treatment of the alignment layers on the electro-optic characteristics of AFLCD's. We applied a different rubbing treatment on different regions within a pixel. This variation of rubbing strengths causes domains with different surface interaction, which results in a different threshold voltage for each domain. In-pixel variation of the rubbing treatment and of the surface interaction influences the double hysteresis of the transmission-voltage characteristic, which is made less steep. The difference between the voltages at which the transmission starts to increase and the voltage at which the transmission reaches its maximum increases and so the selection of analogue grey levels is made easier. The results also show that the finite slope of the double hysteresis which is observed in normal AFLCD's, without extra rubbing treatment is probably caused by variations of the surface interaction.