A 53° twisted-nematic cell for a color reflective liquid-crystal display

Abstract— A 53° twisted-nematic cell for a color reflective liquid-crystal display was developed. It has a mirror electrode inside the panel on the TFT substrate, a twisted-nematic alignment structure, an RGB color filter, a single polarizer, and a light-control film covering the panel. Its advantages include gray-scale capability, low driving voltage, and a wide viewing angle. We discuss the Δn?d, the twist angle, and the front-light control film.     

A 320-dpi 4-in. reflective stacked crossed guest-host display

Abstract— We describe a 320-dpi, 4-in. diagonal a-Si:H TFT-driven monochrome reflective display panel, in which two guest-host nematic liquid-crystal layers separated by a thin polymer film are orthogonally aligned to realize high reflectivity and high contrast ratio simultaneously. The TFT manufacturer used a four-mask process with a high aperture ratio. The structure and characteristics of the panel are presented.     

Ultra-low-power STN-LCDs using multiple-line addressing for mobile telecommunication applications

Abstract— Ultra-low-power-consumption STN-LCDs with high display quality driven by MLA (multiple line addressing) technique have been developed. They realized 3-V driving voltage for 1/33 duty ratio and 5-V driving voltage for 1/65 duty ratio. These are most suitable for mobile telecommunication applications.     

Reflective and transflective color LCDs with double polarizers

Abstract— Reflective color LCDs with double polarizers have been developed by means of optimizing liquid-crystal modes, aperture ratio, color-filter properties, thickness of the glass substrate, polarizers, reflectors, etc. These LCDs are sufficiently bright, display many colors, have good hue, and are light weight with thin outline and low power consumption. Since they have double polarizers, a very high contrast ratio can be obtained. Therefore, they are superior in text character displays. Moreover, transflective color LCDs have been developed without visible deterioration of reflective displays by adoption of a reflective polarizer and backlight system in place of a lower polarizer and reflector.     

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.     

Low‐temperature poly‐Si TFT data drivers for an SVGA a‐Si TFT‐LCD panel

Low‐temperature poly‐Si TFT data drivers for an SVGA a‐Si TFT‐LCD panel have been developed. The data drivers include shift registers, sample‐and‐hold circuits, and operational amplifiers, and drive LCD panels using a line‐at‐a‐time addressing method. To reduce the power consumption of the shift register, a dot‐clock control circuit has been developed. Using this circuit, the power consumption of the shift register has been reduced to 36% of that of conventional circuits. To cancel the offset voltage generated by the operational amplifier, an offset cancellation circuit for low‐temperature poly‐Si TFTs has been developed. This circuit is also able to avoid any unstable operation of the operational amplifier. Using this circuit, the offset voltage has been reduced to one‐third of the value without using the offset cancellation circuit. These data drivers have been connected to an LCD panel and have realized an SVGA display on a 12.1‐in. a‐Si TFT‐LCD panel.     

Dichroic dye‐doped bistable polymer‐stabilized cholesteric‐texture light valve

Abstract— We have carried out systematic investigations on a non‐polar dichroic‐dye‐doped bistable polymer‐stabilized cholesteric‐texture (PSCT) normal‐mode light modulator. The addition of a small amount of dichroic dye (～1.0 wt.%) helps considerably to reduce the transmittance in the OFF state and therefore gives rise to an overall improvement in contrast ratio. Furthermore, collection‐angle dependence of the contrast ratio is reduced by the addition of the dichroic dye.     

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.     

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.     

Technologies toward flexible liquid‐crystal displays

Abstract— Several leading technologies for flexible liquid‐crystal displays have been developed recently at ERSO. The roll‐to‐roll compatible techniques, polymer‐added liquid crystal, have been applied on a film‐like substrate. A flexible black‐and‐white cholesteric liquid‐crystal display was also implemented by photo‐induced phase separation. Color filters placed on a plastic substrate by a low‐temperature manufacturing process was successfully fabricated. A novel design of a wide‐viewing‐angle color plastic LCD was also proposed.