We have developed a novel reflective LCD without polarizers, which is sure to provide excellent visibility (reflectance = 50%, CR = 10:1). Moreover, we have also achieved extremely low power consumption of 10 microwatts to introduce low frequency driving (less than 1Hz) without flicker and image sticking. These characteristics were realized to combine pixel memory circuit and new PNLC material. IntroductionInformation displays have widely prevailed among our daily life. That means, it demands much effort to broaden application fields of electronic displays and to develop the information society further, and therefore the importance of the low power consumption is arising more than ever. Since the power consumption of the conventional electronic displays is still high enough to limit their usage pattern or usage environment. In particular, such functions as the reflective display, the low frame rate drive and the ability to memorize images are quite effective to realize the display consuming low electric power. The display images can be memorized by using the electrophoretic display [1] or the cholesteric liquid crystal display [2], but those displays have required relatively high driving voltages and slow responses.From these viewpoints, the combination of the reflective type of liquid crystal display (RLCD) [3] and the drive scheme such as the low frame rate drive [4] or the pixel-memory circuit [5-6] should be a promising candidate. Since the power consumption of an LCD module generally depends on driving frequency, the lower the frame rate gets, the lower power the module consumes. And the pixel-memory circuit technology enables the module to have any images memorized at the pixels with the data driver suspended.An RLCD using polymer network liquid crystals (PNLC) [7] is the display system to control transmission or scattering of incoming light ray without polarizers. Its remarkable features are high light utilization efficiency due to polarizer-free system and low level of dependence on viewing angle. And a PNLC is one of solutions to realize an energy saving, paper-like display.In the meantime, a PNLC has had a couple of challenges for TFT drive, which are high driving voltage, slow response and low voltage holding ratio. However recent progress of the PNLC materials enables TFT drive of a PNLC by improving the properties above [8].Our objective is to develop an ultra low-power-consumption RLCD with excellent visibilities by using the one-bit pixel memory technology and the PNLC. PrincipleOur newly developed display is composed of the PNLC layer formed between a transparent electrode and mirror reflective pixel electrodes, and the one-bit pixel memory circuits embedded in the pixel area under the reflective mirror electrodes. Pixel Memory TechnologyThe system block diagram of our newly developed pixel memory display is shown in Figure 1. The interface of this display is very simple, because only 5 input lines are necessary for operating this display including power supplies. Timing generator with a 3-line se...

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For the first time, we have developed a 60-inch diagonal size seethrough display using polymer network liquid crystal (PNLC) technology. The color display system by combination of the seethrough display and a projector enables distinguishing eye-catch effect. It creates new application of displays, such as information display, digital signage and substitution of window.

A microstructure film with many micro cavities positioned behind small black dots has been developed for improving LCD viewingangle characteristics. The micro cavities are fabricated by the selfalignment photolithography of the transparent photoresist using the black dots as photo masks. The cavity shapes are optimized by controlling the photolithography conditions.

A microstructure film has been developed to improve drastically LCD viewing angle characteristics (grayscale inversion, color shift, contrast ratio, etc.). By simply attaching it to the surface of commercially available LCD, the LCD has realized the excellent visibility without the blur of the frontal image and the reduction of the contrast ratio under bright ambient light conditions. This technology can be applied to various LCD modes including TN and MVA modes.

Novel reflective color LCDs without polarizers have been developed with using PDLCs and retro‐reflectors. By eliminating polarizers, brightness of our newly developed LCDs has been increased by 51% compared to conventional reflective LCDs, and there still is much room to be improved. What's more, our LCDs can be displayed not only bright text images but also color moving images on, since their response time and driving voltage are significantly fast (63ms) and low (5.5 volts).

-We have developed a new microstructure film for wide viewing liquid crystal displays (LCDs). By attaching it to the surface of a conventional LCD, the viewing angle characteristics of LCD has drastically improved without causing a blur of the frontal image and a decrease in the contrast ratio under bright ambient light conditions. This film can be applied to various LC modes including twisted nematic and multidomain vertical alignment by changing its internal micrometer-size 3D structure. Further, this film can be mass-produced efficiently by self alignment roll-to-roll process.Keywords -optical film, microstructure, liquid crystal display, wide viewing angle, self-alignment, rollto-roll processing.DOI # 10.1002/jsid.249 BackgroundTwisted nematic (TN) mode liquid crystal display (LCD) is still widely used especially in middle-size display, such as small TV, mobile phone, and PC monitor because TN-LCD has many advantages: high transmissivity, fast response speed, wide operating temperature range, high durability, and existing many fabrication lines. One of the disadvantages of TN-LCD is direction dependence of viewing angle characteristics, but previously, it was not a serious issue in the use of middle-size display because middle-size display is viewed from almost a fixed direction. However, new applications of middle-size display such as a tablet computer are recently growing, and with this trend, the improvement of viewing angle characteristics of TN-LCD has been highly expected. Various efforts have ever been investigated to improve the viewing angle characteristics of TN-LCD. They are mainly classified into three approaches. The first approach was to divide a pixel into subpixels or multidomains, 1-5 which required complicated fabrication processes. The second approach was to insert optical compensation films between glasses and polarizers, which still had a grayscale inversion with asymmetric viewing angle characteristics especially at high polar angles.6,7 The third approach was to attach a diffusing film to the surface of LCD, which caused a blur in the frontal image and degraded a contrast ratio under the bright ambient light owing to its backscattering.8-10 Therefore, we have developed a new microstructure film to solve these issues by just attaching it to the surface of TN-LCD. 11-15In addition, the improvement effect of viewing angle characteristics of the microstructure film is not limited to the TN-LCD. We have applied this technology to multidomain vertical alignment (MVA)-LCD. 15In this paper, we mainly report the details of optical design and roll-to-roll fabrication process of our microstructure film. System structure and characteristicsThe structure of our system is shown in Fig. 1. The difference from the conventional system is only a film attached to the surface of the conventional LCD. There were approaches of attaching a diffusing film to the surface of LCD so far, but they usually needed a collimated backlight for preventing the blur of the frontal image. Our system, however, does...

A novel reflective color LCD without polarizer has been developed with using PDLC and retro-reflector. Bright color images including moving images are available with utilizing ambient light. Our novel LCD will create a new application area such as electronic paper.