Because of its readily available technologies, direct view CRT is considered one of the most viable approach for HDTV displays Advantages using direct view CRT include its brightness, contrast, resolution, viewing angles, etc. . However, because of the engineering requirement for HDTV display is much higher than that of standard TV, improvements in all these areas are needed. A review of the current status and the potential solutions for further improvements are discussed in details.

There have been a few new trends for CRT electron gun design in recent years. First, beacause of the rapid improveznts in computer speed and uznory size, more elaborate and accurate computer modeling programs for electron gun design have develope . (1, 2, 3) More and more design engineers rely on the uses of computer modeling to do the design work. Even the US Patent Office has recently started to accept computer modeling results as interchangeable with actual test results. Second, for the high resolution color CRT eletron gun, most companies chose to adopt the COTY(4,5,6) type counon lens design which drastically reduces the aberration coefficient of the main lens. Third, for the best uniform spot performance over the whole sceen of an inline color cRT, a dynamic focusing and dynamic qiiadrupole lens are required. The above mentioned second and third items involve the asynnetric optics design. Most of the tiu, conventional intuitive thinking is not good enough for design optmization. This paper presents a new computer-'designed super high-resolution color electrn gun which asytanetric main lens and dynamic quadrupole region. We also present two cases of the nasured spot performance which are compared to our computer modeling prediction of the sa. design. This indicates that in the current range (from 100 uA to 400 uA) the high—resolution color display is most likely to be used, and the predicted 5% spot size is almost identical to the tested results

The conventional antistatic solutions used in cathode ray tube (CRT) are based on such silane compounds as tetrachioro silane or tetraethoxy silane combined with metallic or hygroscopic materials. This study relates to a single layer antistatic spray coating which uses both thermosetting and thermoplastic polymers (such as poly methyl methacrylate and polysilicone) with several different materials (such as organonta1lic compounds, metallic salts, and hygroscopic compounds) which are applied to obtain the desired antistatic characteristics. In this paper, the effect of the chemical solutions on the electric conductivity will be discussed in detail. The mechanical properties, such as abrasion and hardness, are measured and compared to that of the silane—based systems.

Color CRTs for both consir and display applications are shifting toward larger, flatter and higher resolution. Manufacturing of these tubes with good viewing quality,such as color purity, is a major engineering challenge. One critical area where developnt work is desperate in shadow mask, and thus is the goal of this paper. A flatter RT needs a flatter shadow mask. However, this requirement triggers many engineering concerns, for example: thermal expansivity, formability, and emissivity of the shadow mask. Invar, an Fe-36wt%Ni systematically studied in terms of all requirements described above. It is desired that the mask possesses higher Young's modulus and lower yield strength for the better formability. Invar unfortunably possesses lower Young's modulus and higher yield strength than that of conventional shadow mask material (i.e., AK steel ). Process development to increase the Young's modulus and decrease the yield strength employing proprietary heat treatments and forming process have been studied. It is learned that a material with the grain size of ASTM 6, heat treated at 1000°C, and formed at 2lObC will give an excellent formability. Etnissivity of the Invar mask after forming was also studied under variour conditions. An exnissivity of about 0.9, which is equivalent to that of conventionally blackened AK mask, was obtained through blackening of the Invar mask in steam atmosphere at 600°C for 40 minutes.

Active matrix liquid crystal displays (AMLCDs) have matured and have the potential to replace CRTs in many display applications. This paper will review the working principles, fabrication processes and device performance of AMLCDs. Several competitive approaches will be compared. Device applications and future trends will be discussed.

The control of liquid crystal alignment is of critical importance to the electro-optic performance of a liquid crystal display. Recently a new alignment method was discovered. Instead of the conventional buffing technique, polarized light is employed to treat the polymer alignment layer on the substrate of the display cell for the control of liquid crystal orientation. This non-contact method of aligning liquid crystals offers unique possibilities for display cell repair or reconfiguration after cell assembly. In addition, novel liquid crystal phase devices can be realized for use in optical processing.

A first minimum LC and a second minimum LC were selected with the aid of computer simulation for the fabrication of high contrast LCDs. The contrast ratio in normally white and normally black modes are both higher than 100:1. These LCDs can be used in direct view and projection applications.

A simulation method for the color design of a LCD projector is described in this paper with a goal to achieve better color performance, such as a larger color gamut and color saturation, enough brightness and adequate color temperature.

A new approach to the application of precision coating to flat panel is presented. This coating method is based on the meniscus coating principal, which provides a very uniform and repeatable coating film to the inverted side of the flat panel of virtually any size. Film thickness of typical 400 angstroms to seven microns can be applied with a film variation of +/- 2%. The main advantages using this coating technique are : (1) no coating liquid edge build-up, (2) insensitive to dust contamination, (3) insensitive to machining accuracy and substrate surface topography, and (4) extremely high transfer efficiency.

We have investigated two approaches to improving the electro-optic performance of polymer dispersed liquid crystal (PDLC) films. One involves using a partially fluorinated epoxy based thermoset to serve as the PDLC binding matrix. Results indicate that this causes an enhanced phase separation of the liquid crystal which leads to significant changes in the contrast ratio and fall time of a PDLC film. The other approach involves using duel frequencies to enhance the electro-optic performance of another type of PDLC film. Studies suggest that the hysteresis effect can be minimized and the overall control of the electro-optic response can be greatly increased by adding a second high frequency component to the PDLC driving voltage.

The refractive indices, and birefringence, of some common nematic liquid crystals are measured in the millimeter waves region mainly at 30 GHz. All liquid crystals measured had reasonably large birefringence in the range of 0.1 to 0.17. A proof of concept millimeter wave phase shifter was demonstrated based on magnetic field alignment of liquid crystal. Potential advantages of using liquid crystals in the millimeter wave range for device applications are discussed.

New chiral organic acid 1 and alcohol 2 synthesized from natural lactate and (S)-1-iodo-2- meyhylbutane were used as chiral block for preparing ferroelectric liquid crystals. Six series of chiral liquid crystals were synthesized to study the molecular structure-liquid crystal phase relationship. Different liquid crystal phase sequence K-Sc*-SA-I, K-Sc*-N*-I, or K-N*-I is formed among them. The thermal stability of Sc* phases observed is high. These new FLCs and their mixtures could be useful for practical use. The results also indicate that compounds 1 and 2 could be helpful for preparing new FLCs.

In this study, four kinds of samples have been prepared for investigating the effects of annealing. The active layer which has higher post-annealing temperature may have better crystallinity, but the effects of higher post-annealing temperature may do damage to the interface states. The degradation of ACTFEL devices may be caused by the lower conduction current passed the active layer.

UV-curable films of polymer dispersed liquid crystal composed of nematic liquid crystal and methyl methacrylate prepolymer were prepared. A device was fabricated by sandwiching the cured 'liquid crystal/PMMA' composite films in between two conductive glasses. The device shows electro-optic response properties with an applied voltage. The threshold voltage of the device depends on the curing conditions, degree of polymerization of PMMA and components, etc. The characteristics of the device, including the optical transmittance, response time, and contrast, are highly influenced by following factors, such as component ratio, and monomers. The investigation of SEM photographs for the cured films show that there is a close relationship between the liquid crystal droplet size therein and the electro-optic behavior of devices. From experimental results, when the droplet size increases, the optical transmittance increases and driving voltage decreases. The threshold voltages are between 15 - 20 Vrms and the driving voltage at the clearest state is about 40 - 50 Vrms for the prepared device, meanwhile, the rise time and the fall time at the clearest state are about 30 and 50 ms, respectively, and the contrast ratio is over 12.

As users demand higher quality in flat panel displays (FPD) with larger viewing area and finer resolution, the polysilicon (p-Si) thin film transistor (TFTs) technology becomes increasingly important relative to the amorphous Si (a-Si) TFT technology currently employed in color active matrix liquid crystal displays (AMLCDs). The major advantage are its higher device speed and ability to integrate peripheral drivers with the display substrate, leading to higher panel performance and lower cost. This paper will first review the application and performance of p-Si TFT in AMLCDs. Following will be a discussion on the development of TFT fabrication technology and the critical device characteristics governing the choices of processing techniques. Finally, status of the manufacturing technology to realize low-cost high-performance TFT AMLCD will be summarized.

Polysilicon thin-film transistors (TFTs) using solid phase crystallization (SPC) and liquid- phase deposition (LPD) gate oxide are first realized by low-temperature processes (< 600 degree(s)C). Raman spectra of poly-Si layer reveals that LPCVD a-Si layer following with Si⁺ implantation and SPC at 600 degree(s)C for 48 hours is a superior starting material for active layer. The method of LPD-SiO₂ is described. The physical, chemical and electrical properties of such a new dielectric layer are clarified. The TFTs exhibit sufficient performance for pixel transistors. The field effect mobility reveals much dependence on channel length. The off-state current comprise the resistive current, the thermal emission current and the field enhanced generation current via trap states.

Thin-film transistors (TFTs) have been fabricated by using low-pressure chemical vapor deposition (LPCVD) polycrystalline-silicon (poly-Si) film as the active layer. Various gate dielectrics, i.e. high-temperature gate oxides with different thicknesses, low-temperature thin gate oxides, different combinations of oxide/nitride (O/N) structures with various thicknesses, as well as low-temperature oxide/nitride gate dielectrics have been performed. Their effects on the poly-Si TFTs were investigated. The effective carrier mobility of the devices with thin gate oxides are several time larger than those with thick gate oxides. However, the breakdown voltages of thin gate oxides are too low to satisfy the requirements of TFTs. Silicon nitride deposited by LPCVD can be a substitution due to low fabrication temperatures (700 degree(s)C to 900 degree(s)C), high breakdown field, and smooth dielectric/poly-Si interfaces, but the problem of adopting silicon nitride is the large stress between silicon nitride and silicon substrate. A thin thermal pad oxide between the silicon nitride was therefore grown in order to reduce the high stress at the interface between silicon nitride and poly-Si layer of TFTs. Since thinning the gate dielectrics with O/N structure commits a compromise between better performance and larger stress. Therefore, the optimum thickness of pad oxide is found to be 100 angstroms. Hence, high-performance TFTs with O/N gates can be fabricated at the processing temperatures below 800 degree(s)C to satisfy the requirements of TFTs in the liquid crystal displays (LCDs).

We have deposited silicon nitride (SiN_x) films by plasma-enhanced chemical vapor deposition (PECVD) at 270 degree(s)C. Films are prepared by using silane (SiH₄) and ammonia (NH₃) source gases with hydrogen (H₂) or nitrogen (N₂) dilution. The film properties, including N/Si atomic ratio, hydrogen content, and the etching rate in 5% buffered HF are sensitive to the changes in dilution gases (H₂ or N₂) flow rate during deposition. For films with N/Si equals 1.33 (calculated by Rutherford backscattering, RBS); refractive index ((lambda) equals 6328 A) equals 2.0; hydrogen content equals 13% (calculated by Fourier transform infrared spectrometer, FTIR); and the etching rate in 5% buffered HF less than 50 A/min were achieved. In addition, the deposition rate of SiN_x films were dropped dramatically by adding dilution gases, especially with H₂ (from 4 A/sec to 1 A/sec). 3- inch 92,000 pixel elements a-Si:H TFT arrays with pre-mentioned high-quality SiN_x films as gate insulators have been manufactured. The interlayer short defects of the a-Si:H TFT matrix arrays can be reduced to 3 points by adding dilution gas.

A high-voltage structure of MOS devices has been proposed in this work. Both NMOS and PMOS devices with the high-voltage structure have been fabricated using standard P-well CMOS process with 3 micrometers design rule. In order to increase the breakdown voltage of junction between drain/source and bulk of MOS devices, the high doping concentration of field region is separated from double-diffused drain/source region of MOS devices in this structure. The breakdown voltage of 65 and 70 V has been obtained for NMOS and PMOS, respectively. The purpose of this work is mainly developing a high-voltage MOS device for the circuits design of LCD drive.

Modeling of a liquid crystal display (LCD) includes two parts: one is the calculation of the LC director deformation profile inside the cell the other is the LCD optics computation. For the LC director deformation profile calculation, it is usually assumed all the LC molecules within a pixel respond together uniformly to a driving voltage. This one-dimensional (1-D) simulation is a good approximation for most cases. However, due to the finite size of the pixel, the pixel fringe field may drive the LC molecules near the pixel edge to tilt in a direction different from those in the center of the pixel. To understand the detailed LC director structures inside the pixel and their effect on the display performances (especially for the small sized pixel), the two-dimensional (2-D) or sometimes three dimensional (3-D) simulation is required. The 1-D, 2-D and 3-D simulations of the LC director deformation profile will be discussed. For the LCD optics, besides the 4 X 4 matrix method, another alternative method will also be discussed. Finally, examples using the 1-D, 2-D and 3-D LCD simulations to improve the display optical performances will be illustrated.

Refractive indices of two nematic liquid crystals: 5 CB and 5 PCH were measured from 400 to 820 nm region at various temperatures. Results fit the three-band model well. Through these comparisons, the contribution of (sigma) - and (pi) -electrons to the refractive indices and birefringence of uniaxial liquid crystals are evaluated quantitatively. These physical insights are useful for tailoring liquid crystal molecules with proper refractive indices.

The ideal head-ported display for virtual reality requires features not yet simultaneously achievable. We have attempted to satisfy the need for wide field of view, low weight, balance, color range, brightness, binocular vision, etc. With knowledge of their relationships one can not only prevent over-design, but partially sacrifice some less-important capabilities. Conceptual and experimental studies have been performed towards realizing and improving on such a display system.

A tilt-angle-measurement system for liquid crystal cells has been implemented by using the phase retardation extrema method. It includes the rotation of the liquid-crystal film in a linearly polarized monochromatic light and the measurement of the transmitted intensities as a function of the incident angle with photodetectors. The average tilt angle is determined. The performance of this prototype system has been assessed both by numerical calculation and reliability measurement.

In this paper we study the anchoring energy effects in the nematic liquid crystal confined to a submicron cylindrical cavity. Under the perpendicular anchoring conditions and (2K₂₄ + WR)/K₁₁ > 2 it is shown that uniform axial director configuration becomes unstable. In this case the configuration transition occurs. We have obtained the transition threshold dependence on the uniform electric field applied along the cylindrical axis. The stability of the axial director alignment as a function of cavity radius is considered. Taking into account contributions from both the elastic energy and the surface anchoring energy we discuss some results of Landau- de Gennes theory for the uniformly distributed order parameter. Two cases are explored: W is proportional to S and to S² respectively. It is found the shift of phase transition temperature, the width of instability region. The residual orders are different in these cases.

This paper reviews the current development of the PDLC technology. The original PDLC films using isotropic binders have been substituted by anisotropic binders for the purpose of indices match between the low molecular weight liquid crystals and the binders. A wide- viewing-angle light shutter was produced using a side-chain liquid crystalline epoxy polymer as binder. Recently, a new type of polymer-stabilized cholesteric liquid crystal dispersion (PSCLCD) containing less than 5 wt% of the binder in the dispersion systems was developed. Three different operation modes of cell devices were obtained at zero field: normal-mode, reverse-mode and bistable mode.

This paper describes the polymer-dispersed liquid crystal light valve (PDLCLV) using a polymer-dispersed liquid crystal (PDLC) film and a photoconductive crystal. Bi₁₂SiO₂₀ (BSO) and its application to projection displays. The PDLCLV has many features suitable for large screen displays, including no requirement of polarizers, high transmittance, and high-speed response. We discuss the light scattering and modulation characteristics of the PDLC film, photoconductive characteristics of the BSO crystal, and the design, fabrication and optical input/output characteristics of the PDLCLV. We also describe the configuration of a monochrome projection display consisting of the PDLCLV as an image converter and a liquid crystal panel with thin film transistors as an image source and its image display characteristics.

The present paper describes a new polymer dispersed liquid crystal (PDLC) material with rapid response time of 1 to 2 ms at operating voltage of 40 volts. The improved response time at lower operating voltage was achieved by selection of suitable monomer or oligomer with proper molecular structure combining with unique type of liquid crystal material and cured with UV light. This material has been tested continuously over a year and still functions normally.

Polymer dispersed liquid crystal (PDLC) films with memory electrooptical characteristics were fabricated. The approach made use of phase transition characteristics of smectic liquid crystals. If a smectic is cooled from the nematic to the smectic state in the presence of an electric field, one obtains an aligned smectic. This structure yields a transparent state. However, if the material is cooled in the absence of the field, it adopts a focal conic texture which yields a light-scattering state. The fabrication of these devices, together with their measured electrooptical characteristics, is reported.

Electro-optic behaviors of polymer-dispersed liquid crystal (PDLC) films are not only dependent on materials and environments, but also on the electric field generated by driving voltage waveforms. In this paper, mathematical models for the relative permittivity, rise time and fall time are proposed and simulated. In addition, PDLC films composed of nematic liquid crystal and methyl methacrylate (MMA) are prepared. Light shutters are made from PDLC films with three dimensional polymer matrix. Electro-optic properties are measured using gated rectangular waveforms, and those results show good agreements with simulated results. Finally, the effects of waveform parameters on the rise time, fall time and contrast ratio are discussed.

Liquid crystal mixtures containing new Super Fluorinated Materials as highly dielectrically positive compounds have been developed. The new experimental LC mixtures have threshold values as low as 1.42 V in Viewing-angle Independent Panels, utilizing TN cells with an optical retardation of 0.5 micrometers . Broad nematic phase ranges from -40 to +100 and even +110 degree(s)C have been realized with threshold voltages of 1.8 V and below. Only a small increase of the flow viscosity had to be accepted. Also experimental LC mixtures with higher birefringence values suitable for displays with an optical retardation of 1.0 to 1.1 micrometers , having threshold values of about 2.3 V, have been developed. The surface tilt angles of the new liquid crystal mixtures have been investigated on several commercially available, as well as on new experimental polyimide orientation layers. All polyimides investigated were pre-imidized materials and showed suitable voltage holding ratios for AMDs. On all different alignment layers investigated here, the new liquid crystals lead to increased surface tilt angles, compared to the SFM mixtures available so far. The temperature dependent decrease of the surface tilt angle of the LCs on these new polyimides has also been investigated. Especially for the new LCs optimized for high surface tilt angles the temperature dependence of the surface tilt angle is stronger than for the same LC on high tilt orientation layers for STN application. Nevertheless, even at a temperature of 60 degree(s)C tilt angles of about 2 degree(s) have been obtained. This helps to reduce the occurrence of reverse tilt domains in AM displays. The strong temperature dependence of the tilt angle, found for some combinations of liquid crystals and orientation layers, can compensate the temperature dependence of the threshold voltage in the range from -20 to +40 degree(s)C.

Several new fluoro diphenyl-diacetylene and tolane liquid crystals are synthesized and their physical properties evaluated. These liquid crystals exhibit a high resistivity, high birefringence, low viscosity and low threshold voltage. Owing to their relatively high melting temperatures and narrow nematic range, eutectic mixtures have to be considered. The eutectic mixtures consisting of these fluorinated compounds are particularly useful for active matrix, photoactivated light valve, and polymer-dispersed liquid crystal displays.

The purpose of this study is to synthesize the ester system ferroelectric liquid crystals 4-(4-(2- methylbutyloxy carbonyl)phenyl)-4'-alkoxy-biphenyl-4-carboxylates (MBPABC_n). In addition to the basic physical of single liquid crystal, such as tilt angle, pitch length, birefringence ((Delta) n), spontaneous polarization (Ps), response time and electro-optics properties, etc., and the physical properties of liquid crystal mixture are studied. The FLC mixture of MBPABC₈ and 4-(4-(2-methylbutyloxy carbonyl)phenyl)4'alkoxy benzoate (MOCPAB₈) present smectic C* phase with wide temperature range. In addition, the tilt angle and spontaneous polarization increased as increasing the MBPABC composition. The results indicate that further consideration for device applications can be made.

Ferroelectric liquid crystalline polymethylsiloxane with side chains as mesogenic units was synthesized and characterized by polarized microscopy. These compounds are found to show smectic phase in mesophase region and exhibit spontaneous polarization. Spontaneous polarization (Ps) of PS8 is 127 nC/cm² at 30.6 degree(s)C, and its response time is 15 ms at 86.4 degree(s)C. Optic devices are prepared by sandwiching the liquid crystal polymers (LCP) or LC/LCP in between the two ITO layers and their phase transitions are studied. Two stable textures of LC/LCP composite films are formed during different thermal treatments and the films can be applied as an optic memory medium.

In order to evaluate the interface properties of TFEL with stacked layer insulator structure, four kinds of samples with different insulating layers have been studied. It was found that the EL device with a glass/indium tin oxide/BaTiO₃/ZnS:TbF₃/HfO₂/Ta₂O₅/HfO₂/Al structure exhibited higher brightness and higher efficiency than the other devices.