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.     

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.     

Measuring color breakup of stationary images in field‐sequential‐color displays

Abstract— Color breakup is an artifact perceivable on field‐sequential‐color (FSC) displays, both in stationary and in moving images. In this work, a unique device and a method for measuring color breakup on stationary images is proposed. Rotating the field of view of a high‐speed measurement camera in milliseconds simulates saccadic behavior. The target can be a virtual display, a direct‐view display or a projector image. Captured images can be used for quantifying the color breakup of a target display. The results along with an exploration of their application to breakup characterization will be presented.     

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.     

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.     

Minimum‐voltage driving of small STN‐LCDs by optimized multiple‐row addressing

Abstract— In small STN‐LCDs for portable applications, rows and columns are driven by one IC. The LC supply voltages are generated on‐chip from the battery voltage by voltage multiplying. The total LC supply voltage should be as low as possible to minimize the accompanied power losses. By using multiple‐row addressing, the row and maximum column voltages can be made equal, leading to a minimum LC supply voltage. This occurs when the number of simultaneously addressed rows is equal to the square root of the number of rows in the panel. The LC supply voltage may be minimized further by using a liquid crystal which allows multiplexing of more rows than are actually present in the display panel, while at the same time fewer simultaneously addressed rows are required.     

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.     

High‐performance OCB‐mode field‐sequential‐color LCD

Abstract— Optically compensated bend (OCB) mode is a promising technology for future high‐quality display devices due to its wide viewing angle without gray‐scale inversion and color shift, fast response time, high contrast ratio, and wide temperature range. This paper summarizes the developments of the OCB mode and the optical performance of OCB‐mode field‐sequential‐color LCD.     

Driving passive‐matrix LCDs with low hardware complexity and reduced supply voltage

In passive‐matrix liquid‐crystal displays (LCDs), multiplexing is achieved by using the intrinsic non‐linear characteristics of the liquid‐crystal material. If the electro‐optic characteristic is steeper than necessary for the matrix display, the selection ratio need not be maximized. Instead, the selection ratio can be reduced to match the electro‐optic characteristics of the display. This leads to a reduction in the supply voltage of the drive electronics. We have considered the possibility of using addressing techniques with low hardware complexity along with displays having steep electro‐optic characteristics. Supply voltages for these techniques are compared with that of multi‐line addressing (MLA). The supply voltages of the Hybrid Addressing Technique (HAT), Improved Hybrid Addressing Technique‐S3 (IHAT‐S3), and Improved Hybrid Addressing Technique‐S4 (IHAT‐S4) are lower than that of MLA for the lower range of N. These hybrid addressing techniques with lower hardware complexity are a better choice for driving passive‐matrix LCDs, especially in portable equipment.     

An addressing technique for displaying restricted patterns in rms‐responding LCDs by selecting a few rows at a time

Abstract— An addressing technique that will allow rms‐responding matrix LCDs to display restricted patterns is proposed. This technique is based on the selection of a few rows at a time while scanning the display. In applications such as logic analyzers and oscilloscopes, mostly single‐valued functions of time are displayed. This restriction in the image is useful in enhancing the selection ratio so that good contrast is achievable even with TN‐LCDs. It is shown that a large reduction in the hardware complexity of the column drivers and the supply voltage is possible when the waveforms being displayed do not overlap each other and are equally spaced.     

An optical design for reflective color STN‐LCDs

In reflective color STN‐LCDs, it is necessary to achieve achromatic representation in single‐polarizer STN‐LCD modes. We propose an optimization method for the optical components of single‐polarizer STN‐LCD modes in order to achieve achromatic representation. By applying this method, it is shown that a contrast ratio of more than 20 can be achieved in the normally black (NB) mode. Furthermore, we prove that the normally white (NW) mode can be realized as well as an NB mode which is usually used in current reflective color STN‐LCDs. Comparing the viewing‐angle characteristics of the NW and NB modes, it was found that those of the NW mode are better than those of the NB mode. Particularly, high reflectance can be realized even at larger viewing angles in the NW mode.     

Multi‐color LC/BL algorithm in field‐sequential‐color LCD for color‐breakup suppression

Abstract— The proposed liquid‐crystal and backlight (LC/BL) algorithm presents the dynamic field‐sequential‐color (D‐FSC) algorithm to reduce the color‐breakup (CBU) effect without greatly increasing the subframe rate. The D‐FSC algorithm can intelligently select one adequate color sequence from multiple color sequences according to the image data. In other words, the scope of CBU suppression of the proposed LC/BL algorithm is more extensive than other conventional FSCs. Simulation results show that the CBU suppression can be improved substantially by the proposed evaluation equation.     

Review of viewing‐angle compensation of TN‐mode LCDs using WV film

Abstract— Wide‐view (WV) films for TN‐mode LCDs, which optimize the optical parameters of the polymerized discotic material (PDM) layer and cellulose triacetate (CTA) have been developed. The development concept of the WV film and realization of its concept in the past and for the future will be reviewed. In particular, the discotic molecular alignment control enabled the improvement of the contrast ratio at oblique viewing angles of TN‐mode LCDs. In addition, color shifts at oblique angles are important for large‐screen TN‐mode LCD monitors and LCD‐TV sets. To improve the color‐shift problem, new technologies have been developed.     

Contrast‐ratio analysis of sunlight‐readable color LCDs for outdoor applications

Abstract— This paper presents contrast‐ratio data measured from high‐brightness TFT color LCDs under various ambient illumination levels encountered in outdoor environments. In these measurements, several LCD front polarizers with anti‐glare (AG) and anti‐reflective (AR) coatings have been used. The measured contrast‐ratio data are compared and the impact due to the AG and AR coatings is briefly discussed. The test equipment that simulates different cases of outdoor illumination is also presented.     

Fast‐response nematic liquid‐crystal mixtures

Abstract— High birefringence and relatively low‐viscosity isothiocyanate‐based liquid‐crystal compounds and mixtures were developed. A high figure‐of‐merit (FoM), which implies a fast response time of the described liquid crystals was observed. Using the new UCF mixture in a 2‐μm cell, a submillisecond response time was obtained. The UV stability dilemma is discussed as a common concern for high‐birefringence LC materials.     

Organic‐polymer thin‐film transistors for active‐matrix flat‐panel displays?

Abstract— Organic‐polymer‐based thin‐film transistors (OP‐TFTs) look very promising for flexible, large‐area, and low‐cost organic electronics. In this paper, we describe devices based on spin‐coated organic polymer that reproducibly exhibit field‐effect mobility values around 5 × 10^?3 cm²/V‐sec. We also address fabrication, performance, and stability issues that are critical for the use of such devices in active‐matrix flat‐panel displays.     

Current manufacturing technologies for TFT‐LCDs

Abstract— TFT‐LCD panels for notebook‐PC applications requires a thin and light form factor, low power consumption, and good display quality, whereas the desktop monitor has different requirements such as large panel size, wide viewing angle, high resolution, brightness, etc. However, for the fifth‐generation of mass production, current panel technologies have to improve in order to cope with these requirements. In this article, various approaches to the manufacturing technologies of next‐generation TFT‐LCDs are discussed.     

Liquid‐crystal‐material technologies for advanced display applications

Abstract— Ions were dissolved into the liquid‐crystal (LC) materials from peripheral materials and were also generated by electric dissociation. Moreover, those ions are partly stabilized in the form of hydrated or solvated ions with polar molecules. As the ions in an LC slab of display panel deteriorate the image quality, it is essential that LC materials be free from mobile ions and be resilent to contamination by ions. Studies on the generation and behavior of ions in LC materials and their influence on display image quality were successfully applied to the development of advanced LC materials featuring high reliability and high purity, as well as low operational voltage, resulting in sophisticated LCDs with high image quality.     

Liquid‐crystal displays using printed plastic TFT backplanes

Abstract— In this paper, we present results from a new liquid crystal over plastic printed thin‐film‐transistor (TFT) display. The display demonstrator shows that the processing incompatibilities between the plastic TFT backplane and the liquid‐crystal materials can be addressed to make a stable twisted‐nematic structure. New fabrication processes such as the photo‐alignment of liquid crystals have made it possible to create a new generation of displays, which pave the way towards fully integrated plastic liquid‐crystal‐display technologies.     

Novel WV film for wide‐viewing‐angle TN‐mode LCDs

Abstract— A new optical compensation film refered to as WV‐EA film for TN‐mode TFT‐LCDs has been developed, resulting in higher contrast ratio, wider‐viewing‐angle characteristics, and improved color shift than their predecessors, especially in the horizontal direction. These features of the new WV film were achieved as a result of haze reduction and optimizing the optical characteristics of the polymerized discotic material layer and TAC film. These features are suitable for large‐sized and wide‐aspect‐ratio LCD monitors and TVs.