In order to estimate feedthrough voltage at the trailing edge of a gate pulse voltage, a novel technique for simulation of a-Si TFT-LCDs Was developed. Features of this simulation are as follows: (1) Intrinsic capacitances in the channel area of a-Si TFT are introduced. (2) A new matrix network circuit is used instead of the RC delay circuit. By using this simulation technique, an error between simulation and measurement is reduced to less than 10%.

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A new extraction method of a-Si TFT parameters has been proposed. The field effect mobility and threshold voltage obtained by this method are effective in calculating pixel dynamics using analytical method with sufficient accuracy of ±1% compared to those by SPICE simulation.

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The new developed LSI is most suitable for a source driver of high speed and full color TFT-LCD. The driver is realized 256 gray scales of each color (8 bis) at operation speed of 20MHz max. and can be applied to full color operation. The 256 steps of driver voltage is generated with pulse width modulation using step-voltage inputs for each color in the digital-analog converter unit in the LSI.

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In the active matrix LCD using a-Si TFT, the voltage drop of the source electrode is generated by the parasitic capacitance between the gate and the source electrode. This drop rate is varied by the video signal level because of the anisotropy of the liquid crystal dielectric constant. The difference of .drop rate adds DC voltage to the liquid crystal and it makes a flicker on the display image. To prevent this problem, we measured the optical response characteristic of one pixel and studied the relation between the optimum common electrode voltage and the pixel driving voltage. Based on the result, we have developed the improved driving circuit for compensating the effect of the voltage drop. Using this circuit, we confirmed the 5〜10 dBVrms reduction of flicker level on the LCD module for HDTV projector.

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An 8.4-in. color TFT-LCD is developed. This system is very suitable for a notebook size computer because of its little size, light weight and low power consumption. New 3-bit digital data driver and gate driver are developed for this system. The new data driver can generate 8 gray scales from 4 voltage levels by interpolating other levels in itself. The new gate driver can deal with the Floating Gate Driving by connected directly to the other circuitry. In this paper. theoretical consideration to the Floating Gate Driving Method is also described.

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The Space Modulated FRC (Frame Rate Control) method is widely used to realize a multi-color TFT-LCD. This method produces intermediate gray shades by switching the effecttive voltage applied to the LCD from frame to frame. The conventional FRC, however, had the problem of flicker which occured often with specific image pattern. To solve this problem, we have developed a new Adaptive Space Modulated FRC method of automatically generating such space modulated patterns. We have evaluated the flicker of the picture elements displayed by the FRC using the Multiple Regression. And we have get the relations between the flicker and FRC voltage-amplitude or brightness.

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Display performance at normal incidene and the viewing angle characteristics of liquid crystal displays (LCDs) were evaluated using psychophysical parameters which are related to luminance and color. The results were compared with the evaluated results obtained from subjective estimation. The agreement between the results of psychophysical evaluation and subjective estimation was better in the bright state than in tha dark state In addition, it was found that human eyes are more sensitive to rapid change in psychophysical values with the viewing angle than the value themselves. It was also found that the Iso-ΔH°curves m the bright state are useful in evaluating the viewing angle characterisitcs of LCDs.

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A Reflective PNLC/TNLC double layer display,which consists of a light scattering liquid crystal display;PN-LCD and aTN-LCD,is achieved. The double layer display has a high contrast with a wide viewing angle and independence of the viewing direction. The display performance is measured and discussed.

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A unique multi-page display, on which images can be formed simultaneously through the pages and a desired page can be selected instantly, is reported. The multi-page display consists of stacked PDLC layers. For writing images, an infrared laser beam heats the irradiated regions through the stacked films. The voltages applied to each film are controlled by the input data. Cool regions with a field become transparent, but cool regions without a field become opaque. Any other unheated regions do not change states. The laser scanning makes images simultaneously on all the films.

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We propose a direct view TFT-LCD with a wide viewing angle which uses a polymer-dispersed liquid crystal panel and a pair of polarizers. We call the device a polymer-dispersed LCD with crossed Nicols (PDN). The PDN allows panels to be made with low scattering levels. This suggests the use of fluorinated liquid crystal (F-LC) that shows high voltage holding ratio in TN-LCDs. A voltage holding ratio of over 98% was realized. The vertical viewing range exceeds ±60°, with a contrast ratio over 5 and no image reversal. The range is almost three times the TN-LCD value. The TFT-LCDS fabricated show a high contrast ratio and no image reversal at any viewing angle.

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The factors relevant for the application of liquid crystal polymer composite (LCPC) device fpr HDTV system are discussed from the point of optical projection system. The optical systems were studied using computer simulation and experimental techniques. The LCPC projection display system was optimized. As a result, a total efficiency of 2.6 1m/W and hight contrast ratio were attained in a full-colcor TFT-LCPC projector. The reflective type LCPC device has a potential of obtaining about twice higher brightness. The high resolution (10μm) enough for HDTV application was confirmed. In conclusion, the LCPC projector is one of the most promising way to full realization of HDTV.

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On a large display screen, luminance shading affects picture quality comparing to ordinary small size TV screen. By using HDTV LCD rear projector for home use, compensation of shading are studied on still pictures Picture quality of compensated picture are better than those on the original LCD projector with much shading affecting their picture quality. Brightness of the display and an image content in the picture strongly affect picture quality as like as luminance shading.

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The backlighting illuminaire using the cold cathode fluorescent (CCF) tube has been rapidly used for the light source of the graphic LCDs. However, these backliting tecknologies are not clear, especially the efficiency of backlight for CCF lamp. We analized the process propagating from CCF lamp to the lighting surface and measured the illuminance of the lighting parts. From this result, the new type of backlighting illuminaire has been developed. Its illuminance is above 2000 cd/m^2 for 7.2 watts. for the display area of 10.4 inch. It is available for the full-colored TFT-LCDS.

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