VA Modes Research Articles

42.2: Stress Induced Substrate Mura in Curved LCD

Curving flat substrates creates retardance proportional to the square of the thickness, approximately three times the typical max value of flat substrates. These stress patterns have distinctive interactions with dark state VA and IPS LC modes. Curved substrate stress‐birefringence can create unique circular polarized edge mura through liquid crystal and substrate interactions.

Four Domain Vertical Aligned Nematic Mode by Rubbing

This paper presents a technique for producing a multi-domain VA mode using the conventional rubbing method, which is very simple LC alignment method with low cost. This method is characterized by an aluminum (Al) layer to block rubbing. The Al layer was deposited by low energy thermal evaporation that does not damage the polyimide surface. A simulation and simple experiments were performed to examine the possibility of a multi-domain VA mode using the conventional rubbing method. The proposed multi-domain VA mode will show a rapid response speed and high transmittance due to the lack of disclination formation in a LC cell, compared to the conventional VA modes.

Advanced Patterned Vertical Aligned Nematic Mode to Elevate Transmittance

This paper presents an advanced patterned vertical aligned nematic liquid crystal (APVA) mode as a way of improving the transmittance of the conventional patterned, vertically-aligned nematic liquid crystal (PVA) mode. The APVA was characterized by multi-electrodes, which play an important role in generating a horizontal electric field that prevents LC disclination in the vicinity of the middle region of electrodes between top and bottom slits in PVA mode. The proposed APVA mode focused on improving dramatically the transmittance with excellent image quality. In the simulation, the APVA mode improved the transmittance by more than 22%, compared to the conventional VA modes. Therefore, it is useful to upgrade the LCD display quality.

P‐102: Advanced Patterned Vertical Aligned Nematic Mode with Improved High Transmittance

AbstractWe present advanced patterned vertical aligned nematic liquid crystal (APVA) mode characterized by multi‐electrodes with fixed voltages which play important role to generate horizontal electric field that prevents LC disclination in vicinity of the middle region of electrodes exhibiting patterned vertically aligned nematic liquid crystal mode (PVA mode). The proposed APVA mode is focused on improving dramatically transmittance with excellent image quality. The APVA mode improves transmittance by 20%, compared with the conventional VA modes. So the proposed APVA mode can improve response speed and transmittance remarkably. Consequently, it is useful to upgrade the LCD display quality.

P‐141: Vertical Aligned Nematic Mode with Surface Morphology for High Transmittance LCD Application

AbstractWe present a vertically aligned nematic liquid crystal mode characterized by micro‐lens‐array type surface morphology. The proposed VA mode is focused on obtaining high transmittance with omnidirectionally uniform optical image. In this proposed cell structure, when electric field is on, an azimuthally continuous nematic domain is produced in a pixel. This LCs behavior can improve the optical properties, compared with the conventional VA modes.

59.2: Development of New Optical Films for LCDs

AbstractWe have been developing retardation‐controlled polypropylene‐based films with additives. We propose new optical films having Re value (in‐plane retardation) around 100nm, or less 20nm. These films show high durability as optical properties under certain conditions. The low Re value film can be used for protection films of LCD's polarizer, and the high Re value one can be used for retardation films of VA and other modes of LCD.

16.4: Development of Asymmetric‐Gate‐Coupled Eight‐Domain (AGC‐8D) HVA for TFT‐LCD TVs

AbstractA novel AGC‐8D (asymmetric gate‐coupled eight‐domain) VA mode has been successfully developed to effectively reduce the 60‐degree off‐axis color difference (Δ u'v') of skin color to below 0.02. Compared to other published eight‐domain VA modes, the AGC‐8D HVA mode has also distinct advantages of higher panel transmittance, lower panel‐manufacture cost, and being compatible with a double‐frame‐rate (120 Hz) driving for improving MPRT.

VA-LCD의 측면전장효과에 관한 연구

We analyzed the lowering of transmittance due to lateral field effect in the edge of pixel. We studied the method to solve the problem of VA-LCD. It occurred director distortion and transmittance lowering by strong lateral field in the edge of pixel. For analyzing the director distortion and improving the transmittance lowering, we applied the edge pattern to PVA-LCD of cross pattern. As a results, transmittance in the new VA modes were higher than that of conventional VA modes.

51.3: Thin Coatable Birefringent Films and Their Application to VA and IPS Mode LCDs

AbstractCrysoptix developed a novel approach to manufacturing coatable Thin Birefringence Film (TBF™) retarders based on molecular engineering of organic transparent materials. The advanced approach allows adjusting chemical structure of low molecular weight components with printing deposition techniques (including roll‐to‐roll slot die) to produce the coatable sub‐micron Thin Birefringent Films (TBF™) with the required three‐dimensional refractive index and retardation. We designed a variety of TBF™ with negative A‐plate, negative C‐plate, and biaxial retardation functions. We have developed new designs of VA and IPS LCD modes based on experimental value of refractive indices for negative C‐type and biaxial TBF™ retarders. Numerical simulation and device prototype testing have shown that application of the TBF™ retarders provides efficient optical compensation of LCD working in both VA and IPS modes.

Comparative Study of Director Responses in IPS and VA Modes Based Upon Physical Properties of Practical LC Materials

ABSTRACT The director response times of pure IPS and VA modes were compared by inserting respective material constant values of practical LC mixtures into the equations based upon the Leslie-Ericksen theory. The VA mode was confirmed to be superior to the IPS mode from this aspect due to the difference of the Frank elastic constants for bend and twist. Further superiority was shown quantitatively because of the contribution of the back-flow effect in the VA mode. These results were supported by referring to the molecular theory of the physical properties of LC substances.

P-179L: Late-News Poster: Analysis of Temperature Dependency on the Viscosity Coefficients and Flow-effect of Liquid Crystal, and their Influence on Response Time of OCB, ECB and VA Modes

According to a popularization of LCD-TVs, realization of high-performance moving image LCD, such as field sequential color LCD, is required. This paper points out that we have clarified the temperature dependency of viscosity coefficients and flow effects that are great relevance to response of LC comparing among OCB, ECB and VA modes. From mentioned results, we have designed and realized the high-speed response prototyped OCB-mode field sequential color TFT-LCD of 15-inch XGA in consideration of temperature dependency.

38.4L: Late‐News Paper: A New Vertical Alignment Mode for TFT‐LCDs

AbstractA simple and cost‐effective vertical alignment mode, named Smart Viewing Angle(SVA) mode, for active‐matrix (AM) LCDs was developed where all the domain dividers are fabricated only on the TFT substrate side. The crucial component is the director control electrode (DCE) under the openings of the pixel electrode. The DCE maintains higher voltage than that of the pixel electrode via additional TFTs, which distorts the electric field in such a way that stable domain division is accomplished. Compared to the conventional VA modes where the additional process is required, SVA mode can achieve the wide viewing angle without any additional processes.

21.2: Optimum Film Compensation Modes for TN and VA LCDS

AbstractThe compensation principle to reduce the off‐axis light leakage of crossed polarizers is investigated. After optimizing the retardation films, the simulation results show that the black state of viewing angle of compensated TN and VA modes can be made wider than the angle of view of crossed polarizers. The results are also confirmed by the test cells.