40.1: A New MVA‐LCD by Polymer Sustained Alignment Technology

Abstract

A new MVA-LCD using Polymer Sustained Alignment technology (PSA-LCD) has been developed. This technology can realize a stable alignment with protrusion free structure by polymer sustainment. PSA-LCD has established high brightness, high contrast ratio and fast response speed. IntroductionMVA-LCD (1) has excellent performance such as high contrast ratio, wide viewing angle, rubbing free process and so on. And subsequently developed alignment technology using minutely patterned ITO improved response time drastically (2) . However this technology still needed protrusions because the alignment became unstable without protrusions. We investigated many alignment technologies and focused attention on polymer technology well known as polymer-stabilizing technology. It has been applied to several mode LCDs (3)(4) except vertically aligned mode. We have tried to apply polymer technology to the vertically aligned mode for sustaining the alignment without protrusions.The structure of the minutely patterned ITO we already had developed, can control the tilt directions of vertically aligned liquid crystal molecules. We have developed protrusion free MVA-LCD by the combination of minutely patterned ITO we have developed and the polymer technology, and named it PSA-LCD. We report in this paper the advantages of PSA-LCD and results of 17-inch wide panel fabrication. 2.PSA technology Figure 1 shows the panel structure of conventional MVA-LCD. In this structure, the liquid crystal alignment is controlled by partially located protrusions and ITO slits. Therefore, the alignment in the intermediate region between the protrusions and the ITO slits are not controlled directly and the alignment is not strong enough.On the other hand in PSA technology, we can control the liquid crystal alignment over whole pixel area with the help of polymer layer formed on the surface of the substrate. Figure 2 shows the fabrication process to form the polymer layer. Appropriate concentration of UV curable monomer is added to negative liquid crystal and injected to empty cell. After that, some voltage is applied to the cell. Under this condition, the cell is irradiated by UV light. This process can form the polymer layers on the inside surface of the substrate. The polymer layer formed in this way has the ability to control liquid crystal alignment.In other words, the formed polymer sustains this predetermined alignment. So we can obtain stable predetermined alignment. To realize the uniform predetermined alignment, we applied the structure of the minutely patterned ITO. Figure 3 shows the Common electrode Protrusion ITO Slit Pixel electrode Figure 1. Pixel structure of Conventional MVA-LCD LC Molecule UV Light Figure 2. Fabrication process of polymer layer Monomer PI ITO Polymer layer V

Cell Thickness Dependence on Electric Optical Property of Reverse Mode Liquid Crystal Display

“…A polymer sustained alignment technology has been proposed for a multi vertical alignment mode [13] and the RM of 0.1  1wt% is typically mixed with the nematic LC. In this case, almost RM is polymerized on the substrate, not in the LC bulk [14].…”

VAN LCOS Microdisplays: A Decade of Technological Evolution

“…One of the latest developments is the so-called polymer-sustained alignment for VAN liquid crystal [32]- [34]. For this, reactive mesogens are mixed in the liquid crystal material at a low concentration so that no polymer network will be formed in the bulk of the liquid crystal layer.…”

Transmittance Improvement with Reversed Fishbone-Shape Electrode in Vertical Alignment Liquid Crystal Display

“…The conventional multi-domain VA (MVA) [2][3][4][5][6] and patterned VA (PVA) [7][8][9] have shortcomings, such as low transmittance and slow rise response time. In order to overcome the slow rise response time of such VA modes, the polymer-stabilized VA (PS-VA) mode [16][17][18][19][20] has recently been proposed, but the low-transmittance issue still persists and furthermore gives rise to a power consumption issue when employed in high resolution LCDs such as ultra-high-definition (UHD) LCDs. In a PS-VA device as shown in Fig.…”