A continuous‐viewing‐angle‐controllable liquid‐crystal display using a blue‐phase liquid crystal

Abstract— A continuous‐viewing‐angle‐controllable liquid‐crystal display (LCD) using a blue‐phase liquid crystal is proposed. To realize both wide‐viewing‐angle (WVA) mode and narrow‐viewing‐angle (NVA) mode with a single liquid‐crystal panel, each pixel is divided into a main pixel and a subpixel. The main pixel is for displaying images in both modes. The subpixel is for displaying images in WVA mode and controlling the viewing angle in NVA mode. The device exhibits a good viewing‐angle‐controlling characteristic and high transmittance.     

Sequential‐color LCD based on OCB with an LED backlight

We have fabricated a 13.3‐in. XGA (1024 × 768) TFT sequential‐color liquid‐crystal display using optically compensated birefringency (OCB), illuminated by an LED backlight. We fabricated the sequential‐color display feasible process technology, and examined the performance and potential of a field‐sequential‐color scheme. The display was connected to a laptop computer and examined for flicker.     

Blue phase dual‐view liquid crystal display based on directional backlight system

We design a blue phase dual‐view liquid crystal display (BP DVLCD) based on a directional backlight system. Combining the patterned electrodes with the directional backlight system, the cross‐talk ratio is reduced to only 1.17%. Moreover, the resolution and brightness will be tripled by using field‐sequential color display. In the preferred viewing area, the BP DVLCD has a high contrast ratio of ~1700:1.     

Electro‐optic properties of an intrinsic half‐V‐mode FLCD and its application to field‐sequential full‐color LCDs using a poly‐Si TFT matrix array

Abstract— An intrinsic half‐V‐mode ferroelectric liquid‐crystal display (FLCD) exhibiting a high contrast ratio (300:1), owing to defect‐free gray‐scale capability, with a high response speed (τ ? 400 μsec) and good switchability with TFTs, has been developed. Furthermore, this FLCD features high‐temperature reliability owing to the use of a special hybrid alignment technique. We successfully fabricated an active‐matrix poly‐Si TFT field‐sequential full‐color (FS FC) LCD with XGA specifications and a 0.9‐in. diagonal using a half‐V‐mode FLCD and an RGB light‐emitting‐diode (LED) array microdisplay. It is shown that the fabricated active‐matrix FS FCLCD exhibits good moving‐image performance with high full‐color display capability.     

A field‐sequential‐color display with a local‐primary‐desaturation backlight scheme

Abstract— Field‐sequential‐color technology eliminates the need for color filters in liquid‐crystal displays (LCDs) and results in significant power savings and higher resolution. But the LCD suffers from color breakup, which degrades image quality and limits practical applications. By controlling the backlight temporally and spatially, a so‐called local‐primary‐desaturation (LPD) backlight scheme was developed and implemented in a 180‐Hz optically compensated bend (OCB) mode LCD equipped with a backlight consisting of a matrix of light‐emitting diodes (LEDs). It restores image quality by suppressing color breakup and saves power because it has no color filter and uses local dimming. A perceptual experiment was implemented for verification, and the results showed that a field‐sequential‐color display with a local‐primary‐desaturation backlight reduced the color breakup from very annoying to not annoying and even invisible.     

Spatio‐temporal scanning backlight mode for field‐sequential‐color optically‐compensated‐bend liquid‐crystal display

Abstract— A spatially and temporally scanning backlight consisting of ten isolated micro‐structured light guides has been developed to be combined with a fast‐response optically‐compensated‐bend‐mode field‐sequential‐color LCD in which the liquid‐crystal cell does not contain color filters. The sequential fields of three primary colors are generated by illumination of the red‐, green‐, and blue‐light‐emitting diodes, each illuminating for one‐half of the field, resulting in a luminance of 200 cd/m² for the LCD. The effect of light leakage between the blocks in the scanning backlight in field‐sequential‐color applications was measured and will be described.     

A single‐cell‐gap transflective blue‐phase liquid crystal display based on fringe in‐plane switching electrodes

A transflective blue‐phase liquid crystal display (TRBP‐LCD) based on fringe in‐plane switching (FIS) electrodes is proposed. The proposed structure generates combined fringe and in‐plane electric fields that cause more liquid crystal (LC) molecules to reorient almost in plane above and between the pixel electrodes. The fringe field is mainly generated in the transmissive (T) region, and the horizontal electric field is mainly generated in the reflective (R) region. By optimizing the width of the pixel electrodes and the gap between two adjacent pixel electrodes, the different electric field intensity in the T and R regions contribute to balance the optical phase retardation between the T and R regions. As a result, the proposed TRBP‐LCD exhibits a low operating voltage and high optical efficiency, while it preserves a relatively simple fabrication process.     

High‐performance polymer‐stabilized blue‐phase LCD with low driving voltage

We have developed a polymer‐stabilized blue‐phase LCD in which the diffraction wavelength of blue‐phase liquid crystal is in the ultraviolet region and which is driven at a low voltage of V₁₀₀ = 27 V. Prototypes of 3.4‐in polymer‐stabilized blue‐phase LCDs were made, which include a highly reliable crystalline oxide semiconductor. We succeeded in fabricating not a test cell but a display having a contrast ratio higher than 1000 : 1 for the first time in the world.     

FFS‐mode OS‐LCD for reducing eye strain

In order to reduce eye strain, a driving method for reducing flickers of liquid crystal display (LCD) is devised. For this driving, an oxide semiconductor (OS) is used in a backplane, liquid crystal and alignment layer materials are optimized, and a fringe field switching (FFS) mode with a structurally formed storage capacitor is used. This work reveals that suitable usages of positive and negative liquid crystals differ from each other according to their characteristics. This work also describes an OS‐LCD with a touch sensor we fabricated for mobile devices, which proves the possibility of reducing‐eye‐strain technology (REST) with reduced flickers.     

Polarization‐independent liquid‐crystal‐etalon modulator

Abstract— The experimental demonstration of a polarization‐independent high‐transmission field‐sequential liquid‐crystal‐etalon modulator for portable projection‐display application is presented. Polarization independence allows for high transmission efficiency for laser illumination sources using the polarization diversity method of speckle reduction. These devices can also be considered for LED illumination sources; however, the spectral width of current LEDs does not allow for high efficiency, especially for the green channel. These devices demonstrate millisecond switching needed for field‐sequential‐color generation.     

A viewing‐angle‐controllable blue‐phase liquid‐crystal display

Abstract— A viewing‐angle‐controllable liquid‐crystal display (LCD) is proposed. When the device is only driven by an in‐plane electric field, it exhibits a wide‐viewing‐angle (WVA) mode. And it exhibits narrow‐viewing‐angle (NVA) mode when it is driven by a vertical electric field as well as an in‐plane electric field. In this manner, the viewing angle of the device can be controlled from 100° to 30°. The device exhibits a good viewing‐angle‐controlling characteristic and high transmittance.     

Single‐cell‐gap transflective liquid‐crystal display and the use of photoalignment technology

Abstract— In this paper, transflective liquid‐crystal‐display (LCD) technology will be reviewed, and several new single‐cell‐gap transflective LCD configurations are proposed. Photoalignment technology is studied especially for transflective‐LCD applications. In order to realize the optimal performance of the display as well as a matched transmittance/reflectance voltage curve (TVC/RVC) for the transflective configurations, two different single‐cell‐gap transflective‐LCD approaches will be discussed. The first one is the dual‐mode single‐cell‐gap approach, in which different liquid‐crystal modes are applied to the transmissive and reflective subpixels of the transflective LCD. The other approach is the single‐mode s ingle‐cell‐gap approach, in which an in‐cell retardation film is applied to adjust the performance and TVC/RVC matching of a transflective LCD. Photoalignment technology is used to fabricate the dual‐mode liquid‐crystal cell in the first approach and also the in‐cell retardation film in the second approach. Prototypes of the proposed configurations have been fabricated, which show good performance and a matched TVC/RVC.     

A new field‐sequential‐color LCD without moving‐object color break‐up

Abstract— A new display method for field‐sequential‐color liquid‐crystal displays (FS‐LCDs) that reduces the negative effects of color break‐up associated with moving objects has been developed. The method is called Adjustment of Color Element on the Eyes (ACE), and it relies on the position on the eyes of RGB color sub‐images. It was confirmed that color break‐up also does not occur for peripheral objects when using ACE.     

High‐transmittance in‐plane‐switching liquid‐crystal displays using a positive‐dielectric‐anisotropy liquid crystal

Abstract— The in‐plane‐switching (IPS) mode exhibits an inherently wide viewing angle and has been widely used for liquid‐crystal‐display (LCD) TVs. However, its transmittance is limited to ～76% compared to that of a twisted‐nematic (TN) cell if a positive‐dielectric‐anisotropy LC is employed. A special electrode configuration that fuses the switching mechanism of the conventional IPS and the fringe‐field switching (FFS) to boost the transmittance to ～90% using a positive LC has been developed. The new mode exhibits an equally wide viewing angle as the IPS and FFS modes.     

High‐transmittance in‐plane switching liquid crystal display device driven by three‐level voltages

We propose a single‐layered electrode structure using three voltage levels instead of two to achieve high transmittance in an in‐plane switching liquid crystal display device. The proposed structure consists of two pixel electrodes and one common electrode. By using three voltage levels, we can generate an in‐plane electric field higher than that in a conventional in‐plane switching device. We confirmed that by using the proposed structure, the transmittance of a liquid crystal device can be increased from 29% to 35% at a slightly lower operating voltage without using the double‐layered electrode structure required for the fringe‐field switching mode. The transmittance of the proposed device is higher than that of the fringe‐field switching device.     

Electric‐field‐driven LC lens for 3‐D/2‐D autostereoscopic display

Abstract— The use of an electric‐field‐driven liquid‐crystal (ELC) lens cell for switching between a 3‐D and 2‐D display is proposed. Due to the phase retardation of the non‐uniform LC directors, an ELC lens functions the same as a geometric lens. The parameters of an ELC for 3‐D applications are optimized through the simulation of the electrode configuration and voltage levels. A prototype was made where the ELC lens is placed in front of a liquid‐crystal display (LCD) 15 in. on the diagonal with a 99‐μm subpixel pitch. Under zero voltage, the ELC lens is a transparent medium and the users can see a clear 2‐D image. In 3‐D mode, the ELC lens array performs the same as a cylindrical lens array to the incident vertical polarization under suitable driving voltages. Placing a half‐wave plate between the LCD and ELC lens is proposed to change the polarization of the LCD to be parallel with the polarization lens direction of the ELC lens. The measurement of the horizontal luminance profile, performance of the ELC lens, and feasibility for 3‐D/2‐D switching was verified. The fabrication process for the ELC lens is compatible with the current LCD production process and enables the accurate control of the lens pitch of the ELC lens.     

Prospects of emerging polymer‐stabilized blue‐phase liquid‐crystal displays

Abstract— The prospects of emerging polymer‐stabilized blue‐phase liquid‐crystal displays, or more generally, Kerr‐effect‐induced isotropic‐to‐anisotropic transition, are analyzed with special emphases on the temperature effects. As the temperature increases, both the Kerr constant, induced birefringence, and response time decrease but at different rates. The proposed physical models fit well with experimental results. Some remaining technical challenges associated with this promising display technology are discussed.     

Passive‐matrix‐driven field‐sequential‐color displays

Abstract— Passive‐matrix‐driven field‐sequential‐color (FSC) displays were successfully fabricated. It makes use of a new multiplex driving scheme that does not depend on voltage averaging. Instead, a transient response of the liquid crystal is employed. An addressing and response time of less than 70 μsec and 2.0 msec, respectively, are used. Scanning time compensation is also introduced to improve the brightness uniformity of the display.     

Pixel‐isolated liquid‐crystal mode by using a patterned anisotropic phase separation for flexible LCDs

Abstract— A pixel‐isolated liquid‐crystal (PILC) mode for enhancing the mechanical stability of flexible‐display applications is proposed. Because liquid‐crystal (LC) molecules in this mode are isolated in each pixel by patterned or phase‐separated microstructures, and the two substrates are tightly attached to each other by a solidified polymer layer, the LC alignment is stable against external pressure, and the cell gap of our structure is uniformly preserved against bending deformation of the plastic substrates. The mechanical stability of the PILC structure having plastic substrates was tested for its electro‐optic properties.     

A reflective polarizer‐free display using dye‐doped polymer‐stabilized blue‐phase liquid crystals

Abstract— A reflective polarizer‐free display using dye‐doped polymer‐stabilized blue‐phase liquid crystal (DDPSBP‐LC) has been demonstrated. The mechanism is a combination of electrically tunable light absorption and Bragg reflection. In this paper, the influence of light absorption in DDPSBP‐LC by changing the dye concentration and absorption paths has been studied. Increased dye concentration can improve the contrast ratio of DDPSBP‐LC; however, the response time is the tradeoff. Increasing the cell gap can improve the contrast ratio of DDPSBP‐LC; however, the response time remains the same. The study of DDPSBP‐LC can help in shutter‐glass applications of 3‐D displays and electronic paper.