TN Mode Research Articles

5.2: Field‐Sequential‐Color LCDs Based on Transient Modes

AbstractA new configuration called stressed splay twist (SST) mode is proposed. Such device has much stronger transient effect than conventional TN mode. By using this dynamic approach, the true steady state‐to‐steady state response time of the liquid crystal can be ignored. The transient response time is used, in conjunction with the pulsed light source. A QVGA FSC displays prototype using SST mode is demonstrated.

Numerical Analysis of the Effect of the Step-Coverage on the Parasitic Capacitance

In this paper, we report our numerical study on the effect of the step-coverage structure on the parasitic capacitances in the LC cell. We analyzed the capacitances of the TN mode LC cell by using the 3D-FEM numerical simulator, TechWiz LCD. In order to calculate the parasitic capacitance, we employed the finite element method (FEM) and the energy method. In the case of the capacitances between the data line and the gate line, we found that the capacitance of the planarized structure is about 2.7 times as large as the capacitance of structure generated with the step-coverage. Our theoretical study revealed that an accurate structure generation is very critical to exactly calculate the parasitic capacitance.

39.1: Applying Inorganic Evaporating Deposition Technology to Producing the High Contrast Ratio — 1080P LCoS RPTV

We use the SiOx evaporating technology in the vertical-aligned layer process, and the contrast ratio compared to TN mode panel will be enhanced. We assembled the 65″ 1080P LCoS RPTV using CPT-made panel and optical engine. The contrast ratio of CPT prototype LCoS RPTV is over 3000: 1.

The Electro optic Characteristics of Multi-Cell Gap Fringe-Field Switching Mode

The electro optic characteristics of the fringe-field switching (FFS) mode can be investigated by a combination of in-plane switching (IPS) at electrode center and low-twist TN (= electrode edge). In other words, the smaller optimal optical retardation and higher operating voltage of the IPS mode compared with the low-twist TN mode mean that the retardation and operating voltage (=Vop) of the FFS mode can not be optimized for maximum transmittance at both the center and the edge of the electrode. In the multi-cell gap (= MCG)-FFS mode, the operating voltage at the edge is increased by heightening the cell gap at the edge and is shifted near Vop at the center. One notable result is that the transmittance at the center with increased value D (= the cell gap at the near edge) becomes higher owing to the increased twist angle. In conclusion, the novel FFS mode has a higher transmittance than the conventional FFS mode.

34.2: TN Mode TFT‐LCD with In‐cell Polarizer

AbstractWe have developed TN mode transflective TFT‐LCDs with higher transmittance by integrating polarizers inside the cell with single cell‐gap. This technology improves transmittance up close to that of transmissive TFT‐LCDs and also improves chromatic performance and contrast ratio outdoors by reducing ambient light influence.

유전율 이방성이 음인 액정을 이용한 Fringe-field Switching Twisted Hematic 모드의 전기광학 특성 연구

We have studied 90<TEX>$^{\circ}$</TEX> twisted nematic mode switching by fringe electric field(F-TN mode) using a liquid crystal (LC) with negative dielectric anisotropy. In the device, two polarizers are parallel each other, electrodes exist only on bottom substrate, and one of rubbing direction is coincident with polarizer axis. Therefore, the cell shows a black state before a voltage is applied. With a bias voltage generating fringe-electric field, the LC twists perpendicular to fringe electric field such that the LCs are almost homogeneously aligned except near the bottom surface since the negative type of the LC is used. Consequently, the new device exhibits much wider viewing angle than that of the conventional TN mode due to in-plane switching and relatively high transmittance since the LC director above whole electrode area aligns parallel to the polarizer axis.

P‐118: Viewing Angle Improvement of TN Mode by HD Layer Inside LC Cell and a Compensation Film

AbstractHolographic diffuser(HD) layer inside LC cell was demonstrated, for a transmissive LCD of TFT‐array on Color Filter structure. Master pattern of this layer was generated by holographic method and this pattern was replicated by stamping the master pattern on UV resin. Combined with a compensation film, TN‐mode LCD with this layer showed improved viewing angle characteristics, especially along the up‐down direction.

P‐93: High Performance 17.0″ SVGA OCB Panel with Fast Initial Bend Transition

AbstractRecently, the vigorous researches on the moving picture quality of TFT‐LCDs have been made to overcome their drawbacks in replacing CRTs for TV application. Among them, the fast response OCB mode is thought to have the highest potential for TV application, even though its image quality still needs to be improved. In this regard, we have optimized the cell parameters of OCB mode to get wide viewing angle, high contrast ratio and transmittance as well as the fast response time. Based on these parameters, we have improved image qualities remarkably by adopting these to 17.0″ SVGA proto‐panel, which shows the contrast ratio over 250, viewing angle over 80 degree for all direction except rubbing direction, response time under 7 ms including inter‐gray scale and the transmittance of 90% of TN mode. Especially, by adopting new driving scheme, we considerably reduced the initial bend transition time, which is known as one of drawbacks in OCB mode. We are continuing further research to get the competitive image quality and good reliability, which is comparable to commercially used PVA or IPS mode.

56.1: Novel LC Alignment Method using Diamond Like Carbon Film and Ion Beam Alignment

AbstractA novel LC alignment method has been developed. In this, the conventional polyimide film and cloth rubbing have been replaced by a diamond‐like‐carbon film and an ion beam respectively. The novel method has been used in pilot‐line manufacturing to produce super high quality panels: 15″ TN mode and 22″ IPS mode. These panels will be demonstrated, and the advantage of new method will be discussed.

P‐7: New TACless Wide‐View Film for TFT‐LCDs

AbstractWe have developed a new TACless Wide‐View film, a successor of the current Wide‐View film, which makes the polarizer thinner and allows higher light transmittance, by eliminating one of the TAC films and directly attaching the optical compensation layers to the PVA layer of the polarizer. The new TACless Wide‐View film gives the same optical effect on the TN mode TFT‐LCD as the predecessor.

42.4: Novel Manufacturing Process of TFT‐LCD Featuring C/F on Array and Its Applications

AbstractWe evaluated new manufacturing process featuring with integration of C/F and TFT Array, Rigid spacer as an assistant black matrix, and organic insulator for multi‐purpose of color filter protection and C/F via hole formation. By combining with conventional 5 mask TN mode of top pixel electrode architecture, we could develop novel manufacturing process for displaying performance enhancement and improved productivity. 15.0 inch‐XGA prototype panel with up to 80% of final aperture ratio and 25% increase of display brightness was fabricated.

P‐411: The Analysis of the Electric‐Field Distortion and Abnormal Light‐Transmission Characteristics Due to Foreign Particles in IPS‐ and TN‐LCDS

AbstractThe distortion of electric field and abnormal light transmission characteristics due to foreign particles were studied in IPS and TN mode TFT LCD. The dielectric and ionic particles with varying sizes were considered for the simulation according to their electric characteristics. The simulation shows that the foreign particle introduced into a pixel changes the electric fields within a pixel and affects the light transmission characteristics of the pixel. In both TN and IPS mode TFT LCD, the presence of the ionic particle affects the light transmittance a great deal.

Analyses of In-Plane Switching Mode LCDs

The In-Plane Switching (IPS) mode of liquid crystal displays (LCDs) has a wide viewing angle compared with the conventional 90°-TN mode, but requires a higher driving voltage to reach a maximum transmittance. The electro-optical properties of IPS mode LC cells were analyzed by the LC continuum theory to achieve a maximum transmittance with unnoticeable spectra dispersion at low operating voltages.

Splayed TN Configuration Stability in Domain-Divided TN Mode

In the domain-divided TN mode for a wide-viewing-angle LCD, the LC directors are arranged in the splayed TN configuration by mismatching the pretilt directions on both substrates. For this mismatch...

The Synthesis and Liquid Crystal Properties of certain 4′-Alkoxy-2,2′,3,3′,5,5′,6,6′-octafluorobiphenyl-4-yl-trans-4-alkylcyclohexane-1-carboxylates

Abstract The synthesis and liquid crystal properties of eighteen members of the homologous series of 4′-alkoxy-2,2′,3,3′,5,5′,6,6′-octafluorobiphenyl-4-yl-trans-4-alkylcyclohexane-1-carboxylates are reported. The compounds are low melting nematogens possessing a moderately wide N-I range and have refractive indices comparable with that of fused silica. Because of these properties the compounds may have a potential use as additives to mixtures for the TN mode or in applications where nematogens with a uniquely low refractive index are required.

A Transflective Quarter Wave Plate Dichroic Liquid Crystal Display

Abstract The operational principle of a transflective mode quarter wave plate dichroic liquid crystal display is described. It consists of a dichroic shutter and a polarizer sandwiching two quarter wave plates, one on each side of a transflector. In transmissive mode it acts like a Heilmeier display. The cell construction is discussed and electro-optical measurements are reported. With proper dichroic mixture and cell construction, we have achieved a contrast ratio of 10:1 in reflective mode and 30:1 in transmissive mode. This display is much brighter than TN and Heilmeier mode LCDs as it does not require a polarizer in reflective mode. It also has no unwanted memory effect.

Colorimetric Characterization of TN and GH mode LCDs

Abstract Twisted nematic liquid crystal displays (LCDs) using two kinds of practical polarizers (neutral gray and bluish gray) as well as a guest host mode display device were examined colorimetrically using CIE 1976 (L* u* v* space. Psychophysical colorimetric data of these LCDs were obtained and were compared with the conventional performance parameter, contrast ratio which is determined by physical photometry. The lightness of the twisted nematic display devices for both polarizers are cube root function of the transmittance with the white light. We also made a comparison of the colorimetric data of the guest host LCD with those of the TN LCDs.