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Display Technology, Journal of

Issue 2 • Date June 2006

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Displaying Results 1 - 21 of 21
  • [Front cover]

    Page(s): c1
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  • Journal of Display Technology publication information

    Page(s): c2
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  • Table of contents

    Page(s): 101
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  • A transflective liquid crystal display using an internal wire grid polarizer

    Page(s): 102 - 105
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    To obtain high transmittance and reflectance simultaneously, a single cell gap transflective liquid crystal (LC) display using internal wire grid polarizer (WGP) is proposed. For the reflective mode, the imbedded WGP serves as a polarization-dependent reflector for the ambient light. For the transmissive mode, no achromatic quarter-wave film is needed. This device can be used as a normally black mode (using vertical alignment) and a normally white mode (using twist-nematic alignment), based on the initial LC cell alignment. Detailed electro-optic performance, such as voltage-dependent light efficiency and viewing angle of these two device configurations, is investigated View full abstract»

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  • CSD-a new unified threshold metric of evaluating LCD viewing angle by color saturation degradation

    Page(s): 106 - 113
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    Lower luminance contrast ratio and chromatic changes affect the visual performance (i.e. color shift) of a thin-film transistor liquid-crystal device (TFT-LCD) at large viewing angles. The de facto method of defining viewing angle, contrast ratio of luminance, fails to represent the substantial visual performance viewed at a larger angle. We found the degradation of color saturation, dS*/dthetas, to be an appropriate metric to aid the conventional viewing angle definition (CR ges 10). We empirically determined the threshold for defining the color viewing angles of TFT-LCDs, CVA = {thetaspardS*/dthetas| les 0.03}, which reflects the variation not only in chromaticity but also in luminance. The proposed metric was evaluated by psychophysical experiments, whose results validate the efficacy of the proposed metric View full abstract»

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  • High transmittance in-plane switching liquid crystal displays

    Page(s): 114 - 120
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    We have developed a high-transmittance in-plane switching (HT-IPS) liquid crystal display (LCD) using special electrode design on the same substrate. The featured electrode configuration generates substantial horizontal electric fields between the electrode groups, and fringe fields with rich horizontal components within the regions of electrode groups. The former is similar to the IPS mode and the latter is similar to the fringe-field switching (FFS) mode. The HT-IPS mode exhibits a high transmittance (> 90 % of twisted nematic (TN) mode), as well as wide viewing angle for cells using both positive and negative dielectric anisotropy LC materials. In addition, we also compare the electro-optical performance of the HT-IPS with IPS and FFS cells under the same conditions View full abstract»

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  • Dielectric spectroscopy of metal nanoparticle doped liquid crystal displays exhibiting frequency modulation response

    Page(s): 121 - 129
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (579 KB) |  | HTML iconHTML  

    Twisted nematic liquid crystal displays (TN-LCDs), doped with the nanoparticles of metal, such as Pd, Ag, or Ag-Pd, which are protected with ligand molecules, such as nematic liquid crystal, exhibit a frequency modulation (FM) electro-optical (EO) response with short response time of milliseconds (ms) or sub-ms order together with the ordinary rms voltage response. These devices are called FM/AM-TN-LCDs; they are distinct from the ordinary LCDs featured by the amplitude modulation (AM) response. The phenomena of the FM/AM LCDs may be attributed to the dielectric dispersion of a heterogeneous dielectric medium known as the Maxwell-Wagner effect. It is experimentally shown that the frequency range spreads from several tens hertz to several tens kilohertz and the spectrum is more or less centered about the dielectric relaxation frequency. We formulated a theory based on an equivalent circuit model to evaluate the dielectric relaxation frequency and the dielectric strengths; and we succeeded in explaining the dependence of the dielectric relaxation frequency on the concentration of nanoparticles and the their dielectric and electrical properties, whereas conventional theories based on electromagnetic theory are unable to explain this concentration dependence. This paper reports on the experimental results of the EO effects and the dielectric spectroscopy including the dielectric relaxation times and the dielectric strengths of nematic liquid crystal, 5CB (4-pentyl-4'-cyanobiphenyl), doped with the metal nanoparticles of I'd alone and Ag-Pd composite; and discusses how the observed dielectric relaxation frequency or dielectric relaxation time depend on the concentration of the doped nanoparticles and also their electrical and dielectric properties View full abstract»

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  • Radiation simulations of top-emitting organic light-emitting devices with two- and three-microcavity structures

    Page(s): 130 - 137
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    We demonstrate the simulation results of the radiation properties from top-emitting organic light-emitting devices (top-emitting OLEDs) with two- and three-microcavity structures based on the general electromagnetic theory. The parameters of the layer thickness and complex refractive index of each layer, the locations and density of the oscillating dipoles, and the emission photoluminescence spectrum are varied to optimize the device performance. In evaluating the deice performances, the output spectrum, the intensity distribution, and the viewing-angle characteristics of a top-emitting OLED are concerned. The simulation results are consistent with the Fabry-Perot cavity equation, which can be used as a guideline for designing a two-cavity top-emitting OLED. In such a design process, the dipole position is chosen first. Then the thicknesses of the whole organic layer, the semitransparent cathode, and the dielectric layer are adjusted for optimizing the device performance. In a three-cavity top-emitting OLED, not only the emission intensity and the viewing angle can be optimized at the same time, but also the emission wavelength can be independently tuned. Besides, the use of a three-cavity structure helps to narrow the spectral width and increase the color purity View full abstract»

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  • Improving the performance of organic light-emitting diodes containing BCP/LiF/Al by thermal annealing

    Page(s): 138 - 142
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    In this paper, we examined the effect of post-packaging annealing on the performance of organic light-emitting diodes containing tris-(8-hydroxyquinoline) aluminum (Alq,) or 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) in direct contact with a LiF-Al bilayer cathode. The detailed electroluminescent (EL) characteristics were compared before and after annealing at 70 degC for 5 hrs. It was found that better luminous efficiency as well as greater power efficiency could be achieved for devices with BCP/LiF/Al structure. However, other devices consisting of Alq3/LiF/Al were less affected. It is believed that the thermal treatment helps to enhance the electron injection for the former, and less helpful for the latter View full abstract»

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  • Maximizing Alq/sub 3/ OLED internal and external efficiencies: charge balanced device structure and color conversion outcoupling lenses

    Page(s): 143 - 152
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    In this paper, we report bright, efficient Alq3-based [tris-(8-hydroxyquinoline) aluminum] organic light-emitting diode (OLED) structures that incorporate hemispherical lenses for increased output power efficiency. The 6-layer hybrid (polymer/small molecule) OLED structure contains two spin-coated polymer layers and four thermally evaporated small molecule layers. This structure results in balanced charge injection, thus leading to a more efficient device. The use of index-matched transparent lenses resulted in luminous and external quantum efficiency of 7.5 lm/W and 8%, respectively. The size and shape of the lens was used to control the angular power distribution. Lenses incorporating color conversion media were used to achieve high OLED efficiency in various colors. Saturated yellow, orange, and red devices with external quantum efficiencies as high ~4% were obtained from this approach View full abstract»

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  • On-panel output buffer with offset compensation technique for data driver in LTPS technology

    Page(s): 153 - 159
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1094 KB) |  | HTML iconHTML  

    To overcome the offset voltage (VOS) of output buffer due to large variation on characteristics of thin-film transistor (TFT) in low-temperature polysilicon (LTPS) technology, a class-B output buffer with offset compensation circuit for the data driver is presented in this paper. This proposed class-B output buffer can operate at 50-kHz operation frequency with a 2-8-V output swing for extended graphic array (XGA) application, and it has been demonstrated in 3-mum LTPS technology. Using the offset compensation technique, the VOS of output buffer can be controlled within plusmn100 mV under 2-to-8 V signal operation to achieve a high resolution and quality liquid crystal display (LCD) panel View full abstract»

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  • PLL control scheme for the electronic ballast with a current-equalization network

    Page(s): 160 - 169
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    This paper proposes a phase-locked loop (PLL) control scheme for the electronic ballast with a current-equalization network. The PLL control scheme involves detecting the phase signals of both the resonant-tank input voltage and the two leakage-inductor terminals in the transformer; then the operating frequency of the circuit continuously tracks the resonant frequency as a reference frequency. Based on the tracked reference frequency, the required voltage gain of the resonant tank is regulated by offsetting the operating frequency. Consequently, the operating frequency is lower than the resonant frequency to ensure the zero-voltage-switching (ZVS) condition for less turn-on switching losses on the switches. This paper presents the analysis of the proposed PLL control scheme. Finally, the current-equalizing ability in the dimming range is demonstrated by experiments in order to validate and demonstrate the performance and feasibility of the proposed circuit View full abstract»

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  • Frequency response properties of organic photo-detectors as opto-electrical conversion devices

    Page(s): 170 - 174
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    Frequency performances and sensitivities for three types of organic photo-detector (OPD) were studied for an opto-electrical conversion device. A high efficiency of 19.4 % of the external conversion efficiency and a high cutoff frequency response of 16 MHz were achieved using a mixed-layer between copper phthalocyanine (CuPc) and N, N'-bis (2,5-di-tert-butylphenyl) 3,4,9,10-perylene dicarboximide (BPPC) at a reverse bias voltage of 8 V under red incident light. These results were achieved by increasing exciton dissociation and charge carrier generation and to reduce the number of trapped carriers at the interfaces between CuPc and BPPC. The transmission of a moving picture was successfully demonstrated using mixed-layer OPD as an opto-electrical conversion device. These results indicate that it is possible for an OPD to be used as an opto-electrical conversion device in high-speed optical transmission systems View full abstract»

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  • Using the photolysis of chemically modified gel films preparing ITO fine patterned thin films

    Page(s): 175 - 179
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    A novel technique for the fabrication of tin-doped indium oxide (ITO) fine patterning in sol-gel technology is presented in this paper. The fabricated ITO fine patterning could be obtained through a process which combines film fabrication with film etching. ITO films have good comprehensive property of visible transmittance and electrical conductivity, consequently they have been extensively used as coating electrodes. Indium nitrate (In(NO3)3.4.5H2 O) and stannic chloride ( SnCl4.5H2O) were used as starting materials which were modified with benzytone (BzAcH). The chelate complexes containing indium ions were produced during the process which of forming photosensitive ITO/BzAcH gel films through sol-gel technique. It was found that the gel films are sensitive to both the ultraviolet (UV) light irradiation and their solubility on solvents as well. For example, ethanol was reduced remarkably while the UV absorption peak disappeared with the dissociation of the chelate complexes correspondingly by means of UV-vis and IR spectrophotometers. Utilizing these characteristics, a fine pattern was obtained by irradiation of UV light on the ITO/BzAcH gel films through a pattern mask. of the fine patterned ITO films were heat treated at 500degC for 15 min, the optical, electrical properties and the surface element components were examined by X-ray photoelectron spectroscopy (XPS) spectra in this work View full abstract»

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  • Analysis of 3-D integral imaging displays using the Wigner distribution

    Page(s): 180 - 185
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    Integral imaging is a promising technology for 3-D TV and 3-D display. In this paper, a theoretical analysis of 3-D integral imaging systems is performed in the frame of the Wigner distribution formalism. It is shown that the entire intensity distribution in the pick-up image plane of these systems can be obtained from a single 2-D Wigner distribution function of a single lenslet pupil. This result reveals the Wigner distribution function as a powerful tool for analysis of 3-D integral imaging systems with different pupil functions. As an example, the extension of the depth of field of an integral imaging system with lenslets having amplitude modulation (central obscuration) is proposed View full abstract»

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  • Resistivity network and structural model of the oxide cathode for CRT application

    Page(s): 186 - 193
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    In this paper, the electrical properties of oxide cathode and oxide cathode plus, supplied by LG Philips Displays, have been investigated in relation to different cathode activation regimes and methods. Oxide cathode activation treatment for different durations has been investigated. The formations of the compounds associated to the diffusion of reducing elements (Mg, Al, and W) to the Ni cap surface of oxide cathode were studied by a new suggestion method. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) was used as analytical techniques. Al, W, and Mg doping elements take place during heating to 1080 K (Ni-Brightness) under a rich controlled Ba-SrO atmosphere through an acceleration life test. The chemical transport of these elements was occurred mainly by the Ni cap grain boundary mechanism with significant pile-up of Mg compounds. Al and W show a superficial concentrations and distribution. A new structural and resistivity network model of oxide cathode plus are suggested. The new structural model shows a number of metallic and metallic oxide pathways are exist at the interface or extended through the oxide coating. The effective values of the resistances and the type of the equivalent circuit in the resistivity network model are temperature and activation time dependent View full abstract»

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  • Special issue on high-speed photonic integration

    Page(s): 194
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  • Special issue on semiconductor lasers

    Page(s): 195
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  • Special issue on optical code in optical communications and networks

    Page(s): 196
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  • Journal of Display Technology Information for authors

    Page(s): c3
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  • [Blank page]

    Page(s): c4
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Aims & Scope

This publication covers the theory, design, fabrication, manufacturing and application of information displays and aspects of display technology.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Arokia Nathan
University of Cambridge
Cambridge, U.K.