Yoji Taniguchi

16.5L: Late‐News Paper: A New Design to Improve Performance and Simplify the Manufacturing Process of High‐Quality MVA TFT‐LCD Panels

An MVAMulti-domain Vertical Alignment-TFT LCD panel has been redesigned to improve optical performances and to reduce process step. The optical transmittance was improved by newly introduced protrusion wings to remove undesirable disclination lines caused by edge field effect of the pixel. Also, an aperture of the black matrix on the CF substrate was extended to include whole ITO pixel since the operating mode of the liquid crystal is Normally-Black mode. The protrusions on the TFT substrate was replaced to patterned ITO slit. This results in the contrast ratio improvement, and simplifies the manufacturing process.

25.3: An Ultra-High-Quality MVA-LCD Using a New Multi-Layer CF Resin Spacer and Black-Matrix

An ultra-high-quality MVA-LCD has been developed using a newly designed CF. The Cr black-matrix was replaced by multi-layer CF resin, which was also used to eliminate the conventional bead spacer. The protrusions that are essential to building rubbing-less MVA panels are stacked on the multi-layer CF resin coated by ITO to prevent electrical shorting between the CF and TFT substrates and to maintain the appropriate cell gap. This beadless MVA panel improves the transmittance and cell gap uniformity. Moreover, this new design removes Cr BM from the CF structure and eliminates both spacer dispersion and rubbing from the MVA panel process.

Vertically Aligned TFT-LCDs

Fujitsu has developed several types of vertically aligned TFT-LCD: with protrusion; with photo-alignment; and with comb-shaped electrodes. The protrusion-type TFT-LCD has the best balance of specifications and is in mass- production. It has a transmittance of 5% for a 15-inch XGA LCD, a response of 25 ms (τon + τoff), and a contrast ratio of over 400. The photo-aligned type gives highest transmittance (7.5%) with dual domains. The lamp for UV irradiation can be a tube type and non-polarized UV is possible. We think it is a good candidate for notebook-type applications. The comb-shaped electrode type has the fastest response of better than 17 ms for any gray-scale switching. We think it is a good candidate for video applications.