Transflective Liquid Crystal Display Research Articles

P‐136: High Efficiency MVA‐mode TRLCD

AbstractWe have developed a novel transflective liquid crystal display (TRLCD) that uses a specific pixel structure and Multi‐domain Vertical Alignment (MVA) for driving liquid crystal cell with normal black operation under single cell gap. This structure can provide two individual driving gammas for both transmissive and reflective mode. Due to the single cell gap, it can simplify the fabrication process and obtain the higher contrast ratio. Liquid crystal molecules will reveal much better alignment because of the uniform strength by utilizing the square pixel structure.

P‐137: Photoaligned Transflective Liquid Crystal Display with Single Cell Gap using OCB and Low Twist Nematic Modes

AbstractTransflective liquid crystal display (LCD) with single cell gap consisting optically compensated bend (OCB) and low twist nematic modes has been studied. Since no double cell gap structure is included in the configuration, the fabrication process is easy and only one more step UV exposure is needed during photoalignment process to produce domains. Based on this new configuration, a transflective LCD with high brightness and high contrast could be obtained.

P‐142: Multi‐Domain Alignment Technology by Ink‐Jet Printing

AbstractThis study developed an ink‐jet printing method capable of producing multi‐domain alignment liquid crystal displays. Based on the drop‐on‐demand characteristics of ink jet printing, the ink's location in different alignment manners could be defined in one pixel. This paper describes two practical applications. The first involves integrating the hybrid aligned zone with the homeotropic aligned area in one pixel to create a multi‐domain alignment when the voltage is applied. This proposed method achieved a wide viewing angle. The second, similar approach using ink jet printing was performed on a single‐cell‐gap transflective liquid crystal display. A 2.4‐in 170‐ppi prototype demonstrates mass‐production feasibility.

Transflective In-Plane Switching Liquid Crystal Display

A single cell gap, single gamma curve, and low operating voltage transflective liquid crystal display (LCD) using an in-plane switching (IPS) cell is proposed. In the IPS cell, the pixilated transparent indium tin oxide electrodes are on the top substrate and the reflectors are on the bottom substrate. The electro-optic properties of the transflective IPS LCD are calculated using three-dimensional simulation software. By optimizing the reflector width, the voltage-dependent transmittance and reflectance curves can be matched

Transflective Liquid Crystal Display with Single Cell Gap in Patterned Vertically Aligned Mode

We propose a novel transflective liquid crystal display (LCD) configuration with a single cell gap in a patterned vertically aligned (PVA) mode. In this work, the optical path difference in a single cell gap is simply compensated by introducing pixel electrode structures between transmissive and reflective parts in a PVA mode. In addition, our transflective LCD was constructed with the same optical configuration such as that of polarizers and retardation films over the whole panel area. The simulated and measured electro-optic characteristics in the transmissive and reflective parts of our novel transflective LCD have shown good agreement with each other over the whole gray scale range.

Brightness-Enhanced Transflective Liquid Crystal Display Having Single-Cell Gap in Vertically Aligned Configuration

A brightness-enhanced transflective liquid crystal display having a single-cell gap was demonstrated in a vertically aligned (VA) configuration with a patterned retardation layer. The photopatterned retarder was made of a UV-polymerizable liquid crystal (LC) through a single patterning process. The homeotropic LC alignment in the transmissive region and the planar LC alignment in the reflective region were directly produced on the patterned retarder. High reflectance and fast response characteristics were achieved in a single VA transflective LCD with a patterned retardation layer.

P-162: Transflective LCD in a Patterned Vertically Aligned Mode with a Single Cell Gap

We proposed a transflective liquid crystal display (LCD) with a single cell gap in a patterned vertically aligned mode by adopting different geometry of electrode in the transmissive and reflective parts. Since the difference of the electrode structure induces the difference of the optical retardation in each part, we can easily fabricate transflective LCDs with good electro-optic characteristics even in the same cell gap.

IER Film and Inkjet Printing Method for Full-Color Transflective Cholesteric LCD

A transflective cholesteric liquid crystal display (Ch-LCD) is demonstrated by using the image-enhanced reflector (IER) film on the top of the transmissive region to provide the similar paths for both transmissive and reflective light, thus, to display same image color in any ambience, improving the image quality. For full color display, the inkjet printing was applied and the patterned Ch-LC droplet was successfully deposited on the substrate. Thus, full-color Ch-LCD can be fabricated by IJP.

Transflective Liquid Crystal Displays

In this review paper, a detailed overview of the transflective liquid crystal display (LCD) technology is presented. We first introduce the transflector classifications based on their composition and properties. Then, in reviewing the development history, we investigate the mainstream transflective LCDs, including their operating principles, advantages, and disadvantages. Finally, the image quality issues of transflective LCDs, such as color balance, image brightness, and viewing angle, are discussed.

Electro-optic characteristics and switching principle of a single-cell-gap transflective liquid-crystal display associated with in-plane rotation of liquid crystal driven by a fringe-field

A single-gap transflective liquid-crystal (LC) display associated with in-plane rotation of the LC director was designed. In the device, a fringe electric field drives to rotate a homogeneously aligned LC in plane to optimize polarization efficiency. Rotating degrees of the LC director, 22.5° and 45° were required in both reflective and transmissive regions, respectively. In the device, the cell gap was the same for both regions, and a dark state was irrespective of the cell retardation value at normal direction, which was highly important in massive fabrications. The switching principle and electro-optic characteristics of the device are reported herein.

Mass transport phenomena during lithographic polymerization of nematic monomers monitored with interferometry

Photopolymerization of liquid-crystalline diacrylates is a versatile tool to make optical films for liquid-crystal display (LCD) enhancement. The constant drive towards LCD’s having an improved front-of-screen performance demands optical films with properties that can be adjusted on (sub) pixel level. Birefringent films made from liquid-crystalline diacrylates allow for the required adjustment of the optical property on (sub) pixel level. In this paper we report on the composition of the acrylate mixture that results in planarly aligned nematic films usable as optical retarder in transflective LCD’s as well as the mass transport phenomena that take place during heating of a mask-exposed birefringent film of liquid-crystalline diacrylates. The mass transport phenomena are studied by interferometry as a function of temperature and time. Upon heating a pronounced surface corrugation arises from the latent image formed during the mask exposure. The surface profile largely depends on lateral feature sizes. For 1×1-mm2 areas the exposed areas rise compared to the nonexposed areas, whereas the opposite is observed for 100×100-μm2 areas. Finally, the direction of the mass transport depends on the molecular orientation of the liquid-crystalline diacrylate. The protrusion formed by lengthwise diffusion is 1.7 times higher than that formed by sidewise diffusion.

Electro-Optic Characteristics of Single Gap Transflective Display Using In-Plane Switching Mode

ABSTRACT We have designed a single gap transflective liquid crystal display (LCD) using an in-plane switching mode, where the rotating angle of the LC director between electrodes, and above electrodes, is 45° and 22.5° in average, respectively. Optimization of the cell structures such as electrode structure, cell structure, physical properties of the LC and the LC cell retardation value have been perform to obtain a low-power transflective LCD with a single gap structure and a single driving circuit.

P-110: A Single Gap Transflective Display using a Fringe-Field Driven Homogeneously Aligned Nematic Liquid Crystal Display

We have designed a single gap transflective liquid crystal display (LCD) driven by a fringe electric field, in which the LCs are homogeneously aligned in the initial state. In the reflective and transmissive areas, the degrees of the rotation of the LC director are 22.5° and 45°, respectively. Utilizing this mechanism and an in-cell retarder with a quarter-wave plate that is used below the LC layer, the transflective LCD using fringe-field switching (FFS) mode is realized.

Fringe‐field switching transflective liquid crystal displays

This paper investgates the transflective liquid crystal displays (LCDs) associated with fringe‐field switching (FFS) mode to achieve high image quality. In the past, several cell structures were used to fabricate transflective FFS LCDs. Their structures and characteristics are carefully examined to find their merits and demerits. In addition, we attempt to optimize cell parameters to achieve a single driving circuit.

68.2: A Transflective Liquid Crystal Display Having a Patterned Retardation Layer

We have developed a transflective liquid crystal display (LCD) having a single cell gap and a single LC mode by adopting a patterned retardation layer. In our transflective configuration, a single LC mode of the 60° twisted nematic LC was used for both transmissive and reflective applications. The patterned retardation layer was fabricated using a reactive mesogen by photo-patterning. The measured electro-optic characteristics of our transflective LC cell agree well with numerical simulations. Particularly, the transmittance was found to show similar behavior to the reflectance.

Applications of Microtube Array on Transflective Liquid Crystal Displays for Backlight Efficiency Enhancement

A novel transflective liquid crystal display (LCD) with a microtube array structure to make the most effective use of backlight was demonstrated. By redefining the area ratio of transmissive and reflective regions, high light efficiency in both transmissive and reflective subpixels can be attained. Based on the principle of light collection, a simulation model was established to characterize the features and optimize the microtube array structure. Furthermore, a typical TFT-LCD process was utilized to fabricate the optimized structure. A prototype microtube array was fabricated, and the measured enhancement of backlight utilization efficiency can be as high as a factor of 1.81.

Multimode transflective liquid crystal display with a single cell gap using a self-masking process of photoalignment

We demonstrate a transflective liquid crystal display (LCD), doped with a chiral agent to produce a low helical twisting power, in a multimode configuration consisting of the homogeneous alignment and the hybrid alignment. The multimode transflective LCD was fabricated by a single-step exposure of the UV light through an array of metal reflectors used as an amplitude photomask which gives an alternating homogeneous and homeotropic LC geometry. This single-step UV exposure produces no cell gap variations. In our configuration, the electro-optical disparity between the transmissive region and the reflective region was found to be significantly reduced by the low helical twisting power of the chiral dopant.

Electro-Optics of a Transflective Liquid Crystal Display with Hybrid-Aligned Liquid Crystal Texture

The electrooptics of a newly proposed transflective liquid crystal display (LCD) with hybrid-aligned liquid crystal texture is optimized by simulation. The transflective LCD possesses an ultralow threshold voltage of 0 V and an operating voltage of 3 V. By using the dual cell-gap technology and a symmetric optical structure, the normalized voltage dependences of transmission and reflection overlap completely, and the isocontrast contour shows wide viewing angle and symmetry.

22.3: Distinguished Student Paper: Full‐Color Transflective Ch‐LCD with Image‐Enhanced Reflector

AbstractA full color transflective liquid crystal display with low power consumption is demonstrated by using high Δn cholesteric liquid crystal (Ch‐LC) as an LC layer and building an image‐enhanced reflector (IER) on the top of the transmissive region. The high Δn Ch‐LC can reflect wide band wavelength to display white image. With conventional color filter process, a full color image can be shown. Additionally, an IER on the top of the transmissive region provides the similar paths for both transmissive and reflective light. The two regions can always display same image color in any ambience, thus to greatly improve the image quality of the full color transflective cholesteric liquid crystal display.

P‐100: A Transflective Liquid Crystal Display in a Multimode Configuration

AbstractWe report on a transflective liquid crystal display (LCD) in a multimode configuration consisting of an electrically controllable birefringence mode and a hybrid aligned nematic mode. In this configuration, the multimode transflective LCD was obtained by a single‐step exposure of ultraviolet light, blocked by a metal reflector in the reflective area as an amplitude photomask, producing an alternating homogeneous and homeotropic geometry with no additional fabrication processes and cell gap variations.