A zig-zag defect free ferroelectric liquid crystal display exhibiting fast response speed, high contrast ratio, monostability with grayscale capability has been fabricated by using an especially developed polyimide alignment films and by adopting polymer stabilization with a mesogenic side- chain polymer. Some electrooptic performance of this display as a field sequential type color LCD are described and demonstrated.

Switchable holograms exhibit an electrically controllable diffraction efficiency. Such devices form the building blocks for several applications under active consideration, including optical image and information displays. Several demanding requirements are placed on switchable holograms for these applications, such as high diffraction efficiency, wide on/off dynamic range, low optical scatter, low switching voltage and power consumption, high speed, uniformity and repeatability, low cost, and manufacturability. We describe the challenges and progress in meeting these goals in a single-step photopolymer/liquid crystal composite system. We also discuss the multiple uses of this material and potential applications.

A new discovery has been made for the diffraction ring formation of a nematic liquid crystal. When a beam shines on the crystal of a shallow tilt at 5 degrees, an innermost ring will be formed form the previous innermost ring. While it is at steep tilt of 40 degrees, the new innermost ring will be given rise by the bright center spot. The mechanism is deep-rooted to the electronic polarizability of the nematic liquid crystal. Thus the polarizability can form a complex and yet the most realistic model for the crystal to account for its characteristics. The sensitivity and physical display of two different ring formations of the nematic liquid crystal will open a wide range of investigations including some unknown areas like a calibration of earthquake-prediction detection and some very high-precision instrument applications.

We extend our preliminary investigation of the conic cylindrical-cavities liquid crystal display using vertical aligned liquid crystal structures to obtain a wide viewing- angle. We simulate the director distribution of CCLCD as well as the optical propagation to study the optical transmission and the viewing angle. The simulation of director distribution is based on the tensor form formulation of the free energy density. The differential equations satisfied by the steady-state director distribution are derived from this form of free energy and are solved in conjunction with the Poisson equation. The simulation of optical propagation and the calculation of the optical transmission coefficient are based on the extended Jones matrix method. We first show by simulation that indeed CCLCD can have a wide-viewing angle and gray levels but no gray-scale inversion. The validness of our simulation is also proved by performing some test experiments.

An empirical exponential equation is proposed to characterize the transfer functions of the image signals to tristimulus values of twist nematic (TN) liquid crystal displays (LCDs). Parameters of the empirical equation can be determined according to the colorimetric measurements of the test panel without knowing the panel's physical details. A two-stage forward model is also proposed to model the color characteristics of TN LCDs by using the empirical function. Moreover, a backward model is derived to reproduce desired colors accurately on TN LCDs. The main benefit of the study is that only 12 colors should by measured to characterize color rendering on TN LCDs.

The negative birefringence optical compensation films can be used to significantly improve the viewing angles of single- domain and multi-domain LCDs. This type of optical compensation films are being commercialized and are available from a few major polarizer and optical film manufacturers. Also, the negative birefringence compensation films have been used in several Asia and US TFT/LCD manufacturers and display system developers to improve the TN/LCD viewing angles. Most recently, there are three TFT/LCD panes with improved large viewing cone being commercialized with the use of the negative birefringence optical compensation films. These panels include: (1) US TFT/LCD vendors compensated single domain TFT/TN panels; (2) Sharp compensated 2-domain Super-V TFT/TN panels; and (3) Fujitsu super-wide compensated 4-domain vertical aligned TFT/VA panels. We review the status and major applications of the applications of negative birefringence compensation to TN, STN, vertically aligned LCDs, and parallel aligned LCDs.

We investigate various birefringent optical thin films which can be employed to improve the viewing angle characteristics and gray scale stability of conventional twisted nematic liquid crystal displays. The birefringent phase retardation films include negative uniaxial, positive uniaxial and biaxial films of various orientations. The results are presented and discussed.

The photoinitated polymerization of 2-chloro-1, 4-phenylene bis[4-(6-(acryloyloxy)hexyloxy)benzoate] (1M) and trans-1, 4-bis(4-(2-(2,3-epoxypropyloxy)-ethoxy)-phenyl)- cyclohexyldicarboxylate (3M) were studied. Both monomers exhibit a wide temperature range of nematic phase. The monomers were oriented in their nematic phase at a substrate having been coated with polyimide and unidirectionally rubbed with a nylon cloth. During polymerization, the ordering of the LC molecules was fixed, yielding a uniaxially crosslinked network. The clear LC networks exhibit a birefringence between 0.14 and 0.19, depending on the polymerization temperature. Finally, the nonmesogenic diluents. Tetra(ethylene glycol) diacrylate and 1,2-bis(2,3- bis(2,3-epoxypropyloxy)ethane were mixed with monomers 1M and 3M, subsequently decreasing the birefringences of the obtained LC networks. The LC networks containing non- mesogenic diluent exhibit not only a smaller birefringence but also a weaker birefringence dispersion in the visible region.

We present a mixed-mode twisted nematic (MTN) silicon display integrated with 4-bit digital data drivers. With high bandwidth of the digital data driver, pixel access time of less than 10 ns was achieved. Digital gray-scale addressing technique, which utilizes multiple fields per frame, synchronous field voltages and weighted field time, was applied to increase gray scale from 4 to 8 bits. Chromatic characterization of the display using 3-color-in-1 LED as light source was performed. Contrast ratios on pixel array were 49, 32 and 21, respectively, for red, green and blue colors at 3 V root-mean-squared voltage. It was observed that frame inversion gave rise to higher contrast ratio, while column inversion was less color dispersive. Using color sequential technique, we have demonstrated 4 bits per color for this highly integrated MTN display.

A novel method for adjusting color CRT common lens electron gun's focus performance has been found. It avoids the conventional design's crosstalk between center and outer guns and greatly simplified the common lens electron gun design's optimization cycle.

A 2.3-inch, 150 X 90 pixels, high brightness, high luminance efficiency, and long life of field emission display (FED) with very low power consumption was reported. The spacing between the anode plate and the field emitter plate was 3 mm. The anode plate, coated with Y₂O₂S:Tb phosphor, was processed by a screen printer. A high voltage, varied from 1KV to 9KV, was applied to the anode. It was observed that the luminance efficiency increased as a function of the applied voltage to anode. Moreover, the aluminum film was coated on phosphors, which made the luminance efficiency increase more than 1.7 times, compared to no Al film,when the anode was applied to 7KV. It was demonstrated that the luminance efficiency of phosphor plate is more than 15 lm/W in our FED panel. As well, the low parasitic capacitance design of the field-emitter plate makes the field emission display very power-efficient and with very low power consumption.

The PL and EL characteristics of several blue Alq (BAlq) emitters and the effect of doping with blue and red fluorescent molecules have been studied. Substitution at the 2 and 4 positions was found to produce a substantial blue shift in the emission peak relative to the green Alq and a relatively large improvement in the fluorescence quantum efficiency. Doping perylene and DCJTM in these BAlq was found to be useful in tuning the emission colors form blue to orange-red, including white, with improvements in the operational stability.

The electro-optic effect and viewing angle characteristics of some recently developed single-polarizer reflective liquid crystal displays are compared under same material parameters. The mixed-mode twisted nematic cells and biaxial film-compensated thin homogeneous cells are promising for both direct-view and projection displays employing crossed polarizers. How to improve contrast ratio for the parallel- polarizer displays remain a technical challenge.

We describe hand-held magnified view and single panel color projection displays based on active matrix ferroelectric liquid crystal (FLC) technology. The FLC light-modulating layer is placed on top of a reflective CMOS backplane. This geometry effectively takes advantage of the fast switching speed and high resolution possible in a sub-micron thick layer of FLC and fine design rules available in standard CMOS fabs. The fast FLC switching speed allows both gray scale and color to be generated with time sequential addressing. Current FLC materials are well suited to operation with mainstream 5 volt CMOS processes and offer a clear path to compatibility with newer 3.3 and 2.5 V processes. These lower voltages result in lower power consumption and finer design rules allowing for higher density of on-chip electronics such as MPEG2. This option is difficult to achieve in higher voltage processes typical of nematic on VLSI devices. The reflective quarter wave plate design of the display affords a large angular acceptance resulting in flexibility of optical design as well as excellent contrast and throughput vs. viewing angle.

A high performance reflective-type liquid crystal display (LCD) has been developed. This display utilizes a single polarizer and an inner reflector which eliminates the parallax problem as encountered by the conventional reflective TN LCD. A novel diffusive film is laminated between the polarizer and the LCD cell to overcome the narrow viewing angle caused by the specular reflector. Micro color filters were fabricated on the glass substrate to achieve full color representation. To obtain high contrast ratio and neutral color in gray shading, am mixed-mode twisted nematic LCD is used. The twist angle of the liquid- crystal layers has also been optimized to boost the brightness. Based on these technologies, we have developed a thin-film-transistor addressed reflective LCD panel. Excellent properties such as high contrast of 15:1, fast response of less than 15 ms, wide viewing angle of more than 40 degrees in all azimuthal directions, clear image of no parallax, and full-color capabilities are demonstrated. In addition, the advantageous features of low-power consumption and sunlight readability promise the potential application of this reflective display in future portable information tools, such as digital camera, personal digital assistant, and hand-held personal computer. Finally, preliminary results of a configuration with an inner-diffuser are discussed briefly.

We study the electrooptical properties of the phase-change- guest-host (PCGH) mode liquid crystal display. The PCGH material is a mixture od dye, chiral dopen, and nematic liquid crystal. The material is spread between two glass substrates which have previously been coated with a thin transparent conducting layer and a homeotropic alignment layer. Samples with various thickness-to-natural pitch ratio d/p₀ are fabricated. For each sample, the scroll-to- focal conic texture transition field E_c,c, the cholesteric-nematic phase transition field E_CN and the nematic-cholesteric phase transition field E_NC are measured. Experimental results show that the value of E_CN can fit de Gennes theory well when d/p₀ >= 3.7. Then we measure the ON- and OFF-state transmittance and the response time vs. d/p₀ for each sample. It is found that for d/p₀ >= the d/p₀ ratio can hardly affect the transmittances but affect the response time of the sample film.

A new type of a reflective liquid crystal display is proposed in a twisted hybrid aligned (THA) geometry. In this reflective configuration, a single polarizer and a reflective electrode are used to improve brightness and viewing characteristics. The electro-optical switching between the black and white states is easily achieved in the THA geometry. Numerical simulations are carried out to find the optimum cell parameters such as the cell thickness and the amount of twist required for a stable THA structure. The reflective THA cell provides wider viewing and faster dynamic characteristics than a reflective twisted nematic cell. The effect of a retardation film on device performances is also discussed.

We report results of optical and electro-optical properties of a white reflective display from polymer-stabilized cholesteric texture (PSCT) technology. The new PSCT system is consisted of a cholesteric liquid crystal, photoinitiator and chiral monomer. After polymerizing at homeotropic texture of the cholesteric materials, the PSCT display reflects white light at the planar texture, indicating a broad distribution of helical axes of the cholesteric material. When the cholesteric materials is switched to the focal conic texture, the display reflects a black color with a black paint coated at the back panel.

In this paper, we develop a homeotropically aligned liquid crystal display (LCD) by using gibbous square lattices to make symmetric pretilt of liquid crystals around the pixel. The symmetric pretilt boundary conditions of liquid crystal make the rubbing process no longer needed. Nevertheless, the response of the liquid crystal with negative dielectric anisotropy is too slow when a high voltage level is applied on the display. Therefore, we mix liquid crystal with small amount of monomer. THe weight percentage of monomer is less than 5 percent. After filling the liquid crystal mixture into the display, UV light cures the monomer when an applied voltage induces a symmetric director field. The polymer networks stabilize the director filed. In other words, the directors can reorient definitely in one way when the voltage is applied on or switched off. Experimental data have exhibited that this display to show moving pictures. Tuning the retardation value of compensator A- and C-plate, we make the display's viewing angle with contrast ratio greater than 10 be larger than +/- 70 degrees in all directions of view. The viewing angle without gray-scale inversion is larger than 70 degrees in all azimuthal angles. Furthermore, the color performance is uniform when one measures form all azimuthal angles. The excellent properties of wide viewing angle and fast response promise PSHA LCD applicable in high-end displays.

Four series of trans-cyclohexyl-based tolanes, i.e., 4- (trans-4-alkylcyclohexy)-4'-fluorotolanes, 4-(trans-4-alkyl- cyclohexyl)-3',4'-difluorotolanes, 4-[2-(trans-4-alkyl- cyclo-hexyl)ethyl]-4'-alkyltolanes and fluorinated 4- [2-(trans-4-alkylcyclohexyl)ethyl] tolanes are prepared and characterized. All the obtained compounds display nematic liquid crystalline phases. The results demonstrate that incorporation of a cyclohexyl ring in the mesogen core structure leads to form a wide temperature range of mesophase. However it also increases the tendency to form a smectic phase. The dielectric anisotropy and birefringence of some selected compounds were measured by a guest-host method. All of those compounds studied show relatively high dielectric anisotropy and birefringence.

A novel high-performance thin-film transistor (TFT) with low-high-low band gap structure is proposed. We propose a novel device structure combined with low-band-gap materials for the channel region, high-band-gap materials for the source and drain offset regions, and heavily doped low-band- gap materials for ohmic contact of source and drain electrodes. We found that, as compared to a-Si:H TFT device with conventional inverted-stagger structures, the device with low-band-gap materials in the channel which possesses high conductance can effectively improve the film quality of initial growth active layer near the gate insulator interface and the grown layer. Hence the TFT device parameters such as field effect mobility, threshold voltage, subthreshold swing and ON-current have been significantly improved. This proposed novel structure with high-band-gap material is used to prevent the band to band tunneling and alleviate the high OFF-current in conventional (mu) c-Si:H thin-film transistors. The proposed high performance TFTs with low-high-low band gap structure will have a great impact in application to high resolution thin-film transistor liquid-crystal displays and active-matrix liquid- crystal displays.

The performance of hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) is influenced by the effective intrinsic a-Si:H thickness which is the remaining thickness of intrinsic a-Si:H after n⁺-Si etching for back- channel-etch type a-Si:H TFTs. As the thickness of the as- deposited a-Si:H increases, the on-current and linear mobility of the TFT decrease significantly, but the threshold voltage and saturation mobility only change slightly. It is caused by the series resistance and space- charge-limited current for the as-deposited a-Si:H film. On the other hand, when the thickness of the a-Si:H after n⁺-Si etching decreases from 200 nm to 150 nm, the I_on, (mu) _s, (mu) _lin, and V_th do not change greatly. However, if the effective thickness of a-Si:H reduces to 50 nm, the I_on, (mu) _s, and (mu) _lin decrease and V_th increase. It is the result of the Fermi level pinning at the back-channel surface and plasma-damage for thin a-Si after n⁺-Si etching.

Hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) with single-layer gate insulator have been stressed with DC bias to investigate the device performance. A low defect density interface between the gate insulator (SiNx) and the a-Si:H film is one of the most important factors to obtain high device performance. For the back-channel-etched (BCE) type TFTs, gate SiNx is deposited before a-Si:H film, and the hydrogen plasma was used to treat the SiNx insulator surfaces. From the results of stress experiments, exposing SiNx to hydrogen plasma leads to the charge trapping in SiNx insulator and the state creation in the a-Si:H film. Consequently, the hydrogen plasma treatment of SiNx surface affects not only the SiNx insulator but also the post-deposited a-Si:H film.

In this paper, we demonstrate that the large-area and high- aperture-ratio AM-LCDs can be realized by using planarization technology. Both a-Si:H TFT arrays and Cu-gate electrodes/buslines have been successfully planarized by low dielectric constant organic planarization polymer, benzocyclobutene (BCB). First, the impact of BCB interlayer thickness on vertical crosstalk, feedthrough voltage, and busline load capacitance is analyzed for the high-aperture- ratio pixel cell structure. For a given tolerance margin of crosstalk ratio, the pixel aperture-ratio decreases with an increase of interlayer dielectric constant, and such a reduction in aperture-ratio becomes more distinct in displays having a higher resolution. After the BCB passivation, there is no degradation in field-effect mobility and subthreshold swing for BCE type a-SI:H TFTs having different channel thicknesses and channel lengths. Finally, the electrical characteristics of Cu gate- planarized a-Si:H TFTs is presented. The device has a field- effect mobility of 0.73 cm²/V-s, a threshold voltage of 5.83, a subthreshold swing of 0.71 V/dec, and an ON/OFF- current ratio of 2.5 X 10⁶. These results show that a combination of fully planarized Cu-gate lines and a-Si:H TFT-pixel arrays can be developed for large-area, high aperture-ratio, and high definition AM-LCDs.

The effects of the deposition of PECVD hydrogenated silicon nitride (SiN_x:H) on indium tin oxide underlayer has been investigated. PECVD SiN_x:H films were deposited with various film thickness, substrate temperature, gas flow rate, pressure, and RF power. Two kinds of ITO films prepared wither ex-situ or in-situ thermal annealing methods are examined by PECVD SiN_x:H deposition. Experimental results have shown that the formation of whitened ITO is related to redundant reactive species from SiH₄ and H₂ during the initial stage of SiN_x:H deposition. NH₃/SiH₄ flow ratio is found to be one of the key factors to affect whitening of ITO films during SiN_x:H deposition. In-situ annealed ITO films could be more chemically stable than ex-situ annealed ones since in-situ annealed ITO films have less optical degradation than ex- situ annealed ones after PECVD SiN_x:H deposition.

The optical performance of a display was found to be strongly dependent on the array designs and driving methods. The storage-capacitor-on-gate (SCOG) design commonly used in TFT-LCDs showed significant different characters from a display using the storage-capacitor-on-common design. The difference could be qualitatively explained by a voltage spike effect due to the capacitive coupling in the SCOG design. In this paper, the details of the simple model in correlation with the optical measurement results will be reported on.

A novel device structure for vertical bottom polysilicon (poly-Si) gate thin film transistors (TFTs) with dual-gate and offset structures is proposed. The new device, double- vertical-channel TFTs (DVC TFTs), allows suppression of leakage current and improvement of the photolithography limitation for large panel fabrication because of a deep- submicrometer channel length determined by the thickness of poly-Si gate. A 0.3 micrometers vertical-channel poly-Si TFTs is demonstrated on oxidized Si wafer. For low temperature poly- Si TFTs, several DVC TFTs processes are developed and demonstrated, including excimer laser annealing for the recrystallization of active layer and dopant activation.

As the use of TFT flat panels in today's technology is rapidly increasing, there is further need for advanced production processing. New such systems have to fulfill multiple tasks combining latest research data with manufacturing requirements. Improvements in laser technology as lifetime extension of components and reduction of energy fluctuations have led to the acceptance of these new manufacturing devices on the production floor. Additionally 'state of the art' optics and handling units were introduced to fulfill the industrial demands.

Physical Optics Corporation has developed a unique technology and processes to fabricate a 3D display system that does not require wearing glasses or other eyewear. The authors present the result of true 3D (T3D) monitor development, the third generation T3D being based on a holographic multiplexing screen. The monitor displays 3D autostereoscopic information to three viewers. Holographic multiplexing allows a large number of viewers to see the 3D effect without compromising resolution or having to wear any type of special glasses or goggles. The 3D monitor can deliver high resolution graphics -- 1024 X 480 pixels -- as well as NTSC video in both composite and S-video formats.