Tuesday, 4 July 2006 - 12:00 AM
DEVIP-29

Patterned vertical alignment liquid crystal device with crossed stripe-electrode patterns

Jong-In Baek, Jae Chang Kim, and Tae-Hoon Yoon. Department of Electronics Engineering, Pusan National University, San 30, Jangjeon-Dong, Keumjeong-Ku, Busan, South Korea

LCD modes using vertical switching show relatively high color-shift, whereas those using horizontal switching show relatively low color-shift and inherently wide viewing angle characteristics. Because the retardation value for a specific gray level varies more sensitively depending on the incident angle, the vertical switching modes show relatively poor performance in color-shift point of view, than that of the horizontal switching modes. For the patterned vertical alignment (PVA) case, the multi-domain structure has been employed to reduce the color-shift, so-called super PVA (S-PVA) mode. Each pixel in the S-PVA mode is divided into two domains. Each of them has different tilt angles in grey, i.e., θA and θB, so that the color-shift can be significantly enhanced. Nevertheless that problem in the PVA mode is still such an issue. In this work we report the PVA mode with mutually-crossed electrode patterns, as shown in Fig. 1. Stripe-patterns of top and bottom electrodes are perpendicular to each other so that symmetric fringe-field is induced with applying voltages, resulting in point-symmetric liquid crystal (LC) distribution. Continuously formed tilt angles and symmetric LC distribution in grey are expected to result in reduced color-shift. Moreover, by using the proposed electrode structure for the PVA mode, the transmittance is also expected to be increased. The domain boundaries in conventional PVA structure remain dark even in the bright state, as shown in Fig. 1, which is caused by formation of the 4 domain structure, i.e., ±45° and ±135°, while the proposed structure confirms multi-domain structure without artificial division. To confirm these characteristics, voltage versus transmittance curve, viewing angle, color-shift etc. will be examined.


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