A new optical method for the measurement of liquid crystal pretilt angles has been developed. Using this method full range of pretilt, 0℃~90℃ can be accurately determined by the polarization direction, providing no optical birefringence inside homogeneously aligned liquid crystal cells, of obliquely incident light to the cells. The measurement principle is described in detail and the optimum measurement conditions including the measurement accuracy of the method are analyzed.
In FLTN-LCDs whose LC layers are twisted less than 90° with retardation film, high contrast ratio, sufficient gray scale and wide viewing angle conditions are obtained by computer simulation. Also, electro-optical characteristics are compared optimized FLTN-LCDs with conventional TN-LCDs in NB and NW modes respectively.
That LCD color display can be widely distributed in the next generation is contingent to the price; however, color filter still costs one-fifth of productive cost. How to slash down the productive cost of color filter is the topic to study. There are so many methods to produce color filters. In ERSO, we choose pigment dispersion method as our best approach. During conventional exposure method, the yield is not so satisfied for makers. In this paper we propose a back-side exposure process for color filter fabrication. From the point of enhancing throughput and improving yield, back-side exposure method is able to solve some of the fabricating problems. I would later on discuss detail fabricating process and result of that.
Issues in fabricating color filters with all-dielectric optical interference technique are studied. The color filters are constituted of multiple thin layers of SiO_2 and TiO_2 deposited alternatively to form bandpass or edge filters. Advantages of all-dielectric filters, such as high transmittance, low absorption, high color purity, and good color reproduction, are discussed and compared with dye-gelatin filters. Thickness variations of thin film layers have been analyzed to assess the optical tolerance on the fabrication of color filters using physical vapor depositions.
Color rendering is an important parameter to evalute the performance of a display. Uniformity of color rendering by digital driving methods of equal voltage change (EVC) and equal transmittance change (ETC) were studied. For each driving scheme, color differences of 4096 RGB digital combinations using CIELUV are caleulated. Histograms of the number of diseriminated colors v.s. hue angle are compared. More uniform color rendering of a LC module can be achieved by ETC driving.
Large size diagonal multicolor LCD is of interest for note-book PC development at present market trend. However, when the highly resistant materials such as Cr or Ta is used as gate bus line, the gate pulse is delayed and its waveform is distorted at the other end of the panel as gate bus line panel display. Al is a material with low resistivity and ' suitable for large panel display, however it gives rise to hillocks due to different thermal expansion coefficient between Al and SiNx during thermal processing and generates defects resulting in shorts between the electrodes. A12O3 film has been proposed to be the best pretective layer against hillock formation prepared by anodic oxidation. In this study. Al2O3/SiNx dielectric films suitable for large size a-Si:H TFTLCD have been prepared by anodization and PECVD. Al2O3 layers were formed at various pH value. and H2O% in anodic solution.
We have studied the performance and stability of the hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTS) using a single layered SiO_2 gate insulator. The effects of H_2, NH_3, N_2 plasma exposures on the SiO_2 on the performance and stability of a-Si:H TFT have been investigated. The NH_3 or N_2 plasma exposure improves the performance of a-Si:H TFT significantly, resulted from the nitrification of SiO_2. On the other hand, the H_2 plasma exposure on SiO_2 surf:ace gives little improvement in the performance of a-Si:H TFT. The stability of the a-Si:H TFT with N_2 or NH_3 plasma treated SiO_2 is much better than the a-Si:H TFT with no plasma treatment.
Considering the thin film transistors (TFT's) in the present applications In active matrix liquid crystal displays (AMILCD), the effects of the interface states and the fixed charges at both the rear and front interfaces, i.e., the semiconductor surface apart from and on the gate insulator, respectively, for the thin hydrogenated amorphous silicon (α-Si:H) films have been studied. It is found that the rear interface fixed charges and states will predominantly influence the electrical characteristics of the TFT's as much as the front interface ones do if the semiconductor films are thin enough.
We have investigated the hydrogenation effects on the poly-Si TFTs with various multi-channel structure poly-Si TFT. Especially, we have proposed a new multi-channel structure in order to verify the dominant hydrogenation pathway and this structure employs the gate electrode is surrounded with the poly-Si active layer in the source/drain region. We have characterized the fabricated new poly-Si TFT and compared with the conventional multi-channel TFT of the identical dimensions. Compared with the conventional device, the new device is more effective for increasing the carrier mobility. As a result, we have found that the dominant hydrogenation pathway may be a diffusion through active poly-Si layer into the channel region.
Liquid-Phased Deposited (LPD) SiO_2 was successfully developed around room temperature. It's compatible with CVD SiO_2 and applied in poly-Si TFT as gate insulator and/or passivation layer at the first time. Conventional, Dual-Buffer Drain (DBD) and Self-Induced Offset (SIO) poly-Si TFT were proposed and characterized, respectively. We found device performance was effectively improved by incorporation of LPD oxide into DBD and SIO TFT, which can be therefore utilized as driver elements and switch transistors for AMLCD.
Characterizations were carried out on the pixel feedthrough-voltage of TFT-LCD to obtain the optimum stroage capacitance(Cst) of pixel. The contrast characteristics were measured with respect to the gate addressing voltage and pulse width, the addressing line resistance (Rg), and the storage capacitance (Cst) of pixel. The electro-optical properties of 9.4" TFT-LCD have been investigated with the design parameters of pixel.