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Display Technology, Journal of

Issue 3 • Date March 2014

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Displaying Results 1 - 17 of 17
  • 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): 169 - 170
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  • Dimmable AC LED Driver With Efficiency Improved Based on Switched LED Module

    Page(s): 171 - 181
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1742 KB) |  | HTML iconHTML  

    In this paper, one AC light-emitting diode (LED) driver with high power factor (PF) and low total harmonic distortion (THD) is adopted, which is added with the proposed switched LED module and is controlled based on the field-programmable gate array (FPGA). By doing so, the efficiency of such an AC LED driver can be improved significantly. This switched LED module is constructed by several LED strings, which have individual series-connected MOSFET switches. As the switch of the switched LED module is turned on, the corresponding LED string is short-circuited and hence is not conducted, whereas as the switch of the switched LED module is turned off, the corresponding LED string is conducted due to the redundant input voltage across this LED string. Therefore, the redundant input voltage across between the collector and emitter of the BJT current source can be reduced, that is, the unwanted power dissipation in the BJT current source can be decreased, so as to upgrade the efficiency of the overall system. View full abstract»

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  • Depth-of-Field Enhancement in Integral Imaging by Selective Depth-Deconvolution

    Page(s): 182 - 188
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2063 KB) |  | HTML iconHTML  

    One of the major drawbacks of the integral imaging technique is its limited depth of field. Such limitation is imposed by the numerical aperture of the microlenses. In this paper, we propose a method to extend the depth of field of integral imaging systems in the reconstruction stage. The method is based on the combination of deconvolution tools and depth filtering of each elemental image using disparity map information. We demonstrate our proposal presenting digital reconstructions of a 3-D scene focused at different depths with extended depth of field. View full abstract»

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  • A New Compensation Method for Emission Degradation in an AMOLED Display Via an External Algorithm, New Pixel Circuit, and Models of Prior Measurements

    Page(s): 189 - 197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2070 KB) |  | HTML iconHTML  

    A new external algorithm with sensing circuit are proposed to compensate AMOLED display degradation. The compensation is enabled by first evaluating degradation level of OLEDs based on the OLED anode voltages detected by a newly-designed sensing subcircuit. According to sensed voltages, the external algorithm selects appropriate built-in models to compensate OLED degradation with the aim to achieve expected OLED emitted luminance. The models are established based on prior measurements to prescribe the relations between luminance and current (L-I) and luminance and voltage (L-V) of each OLED. In this way of compensation, the proposed method is able to incorporate negative effects of OLED degradation aggravation while increasing driving current to compensate the original decay in OLED luminance. Moreover, another algorithm along with the 4T0.5C pixel circuit as presented in prior studies are adopted to compensate process variation in Vth among pixels for improving the emission uniformity of an AMOLED panel. Experiments are conducted by combining the external algorithm with sensing circuit and the pixel circuit to validate the performances of compensating and alleviating OLED degradation. View full abstract»

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  • Improved Viewing Zones for Projection Type Integral Imaging 3D Display Using Adaptive Liquid Crystal Prism Array

    Page(s): 198 - 203
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1365 KB) |  | HTML iconHTML  

    In this paper, we present a novel projection-type 3-D integral imaging display with an adaptive liquid crystal (LC) prism array. Comparing with conventional integral imaging display, the proposed system demonstrated that the viewing zones for a projection type integral imaging display was successfully extended by time-multiplexed technique and without any mechanical movement. To the best of our knowledge, this is the first report on combining an adaptive LC prism array with the projection-type integral imaging 3-D display. The proposed display is attractive for future wide viewing zone projection-type integral imaging 3-D displays. View full abstract»

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  • GaN-Based Light-Emitting-Diode With a p-InGaN Layer

    Page(s): 204 - 207
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (790 KB) |  | HTML iconHTML  

    GaN-based LEDs with a p-InGaN layer was proposed and fabricated. By inserting the 50-nm-thick p-In0.01Ga0.99N layer, it was found that we could reduce the 20 mA forward voltage from 3.34 to 2.99 V. It was found the inserted p-InGaN layer could also reduce the efficiency droop from 36.7% to 23.8%. View full abstract»

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  • Polarization-Preserving Light Guide Plate for a Linearly Polarized Backlight

    Page(s): 208 - 214
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (919 KB) |  | HTML iconHTML  

    We analyze the polarization-preserving property of two conventional edge-lit light guide plates (LGPs) based on scattering dots and refractive microgrooves and find that these two structures almost completely depolarize the incident linearly polarized light. We then propose a new edge-lit LGP based on total internal reflection (TIR). Simulation results show that such a TIR-based LGP can largely preserve the polarization state of the incident linearly polarized light. The polarization efficiency is 77.2%. By incorporating a linearly polarized LED to our proposed LGP, the overall optical gain is 1.54 compared with the backlight system with an unpolarized LED. At on-axis, the luminance is 2.4× higher. Because the output light is concentrated near the surface normal direction, no additional brightness enhancement film is needed. This polarization-preserving LGP enables a polarized or partially polarized LED backlight to be used, which in turn greatly enhances the optical efficiency of a LCD. View full abstract»

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  • The Frequency Modulation Electro-Optical Response of Holographic Polymer Dispersed Liquid Crystal Display Doped With Nano Ag

    Page(s): 215 - 222
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1484 KB) |  | HTML iconHTML  

    Holographic polymer dispersed liquid crystals (H-PDLCs), which is one of promising material for LC display, when doped with nanoscale silver (nano Ag) exhibit a unique electro-optical response to frequency modulation. We established an equivalent circuit model for H-PDLC doped nano Ag gratings according to Maxwell-Wagner effect and calculated relaxation frequency for three concentrations of nano Ag. We found that the frequency modulation and doping concentration have a close effect on threshold driving voltage of H-PDLC gratings. It is experimentally shown that the lowest threshold driving voltage can be obtained when the driving frequency is located just around the recipe's dielectric relaxation frequency. It is possible to decrease the driving voltage of H-PDLC through selection of suitable driving frequency as well as via doping with appropriate concentration of nano Ag. View full abstract»

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  • Design of Optical Module With High Stability, High Angular Color Uniformity, and Adjustable Light Distribution for Standard Lamps

    Page(s): 223 - 227
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (657 KB) |  | HTML iconHTML  

    In the paper, an optical design for a standard light source is proposed and demonstrated to perform high stability, high angular CCT (correlated color temperature) uniformity, and adjustable light pattern from a Lambertian-like pattern to a narrow light pattern with a full-width at half-maximum (FWHM) angle of 60 °. The optical module contains a color-mixing cylinder, a diffuser, and an absorbed cylinder. The simulation well predicts the corresponding measurements and the angular CCT deviation can be kept a certain low level, which is much lower than a general phosphor converted white LED. In addition, we apply a pcW-LED of CREE XML as the light source to the optical module to show the general adoptability of the optical module. The measurement shows that the similar behavior, with adjustable light pattern from 120 ° to 60 °. In addition, the angular correlated color temperature deviation (ACCTD) is always kept an extremely low level. View full abstract»

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  • Ultra-Bright Heads-Up Displays Using a Method of Projected Color Images by Combination of LEDs and Polymer-Dispersed Liquid Crystals

    Page(s): 228 - 234
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1197 KB) |  | HTML iconHTML  

    A heads-up display (HUD) commonly uses liquid crystal technology to generate images. However, the intensity of the light decreases significantly due to passing through polarizers. Therefore, a polarizer-free display is a superior approach to utilize light more efficiently. We demonstrate the feasibility of using polymer dispersed liquid crystal (PDLC), which consists of polymer and liquid crystal, as an optical shutter to fabricate a simple see-through projected display device. The unique electro-optical characteristics of PDLC make it suitable to define the projected image shape. In our device, we used a 36 watts collimated light emitting diode as a backlight source so that the projected image can also be seen clearly under daylight. Since PDLC does not require/utilize polarizers, it achieved high light efficiency ( ~ 70%). In this paper, we showed promising results of projected images with various colors (red, green, and blue) that can be applied to see-through projected displays. From our experimental results, the see-through projected display device by PDLC can achieve a contrast ratio of 1000:1 and the response time is approximately 15 ms. The driving voltage is less than 25 V and brightness is over 3000 nit. View full abstract»

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  • Digital Holography Using Spectral Estimation Technique

    Page(s): 235 - 242
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2031 KB) |  | HTML iconHTML  

    We propose a technique capable of obtaining spectral information and three-dimensional information of objects. This technique is based on digital holography and spectral estimation technique. In this technique, multiple lasers operating at different wavelengths, such as red, green, and blue, are used to record the complex amplitude of the object in digital holography, and multiple reconstructed monochrome images can be obtained by each wavelength. Spectral estimation technique is used to estimate the spectral reflectance distribution of the object from the multiple reconstructed monochrome images. Through the spectral estimation technique, the spectral reflectance distribution of object can be obtained. The effectiveness of the proposed method was confirmed by a numerical simulation and an experiment. View full abstract»

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  • Open Access

    Page(s): 243
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  • IEEE Xplore Digital Library

    Page(s): 244
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  • Journal of Display Technology information for authors

    Page(s): C3
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  • [Blank page - back cover]

    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.