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Display Technology, Journal of

Issue 2 • Date June 2008

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Displaying Results 1 - 25 of 30
  • [Front cover]

    Page(s): C1
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    Freely Available from IEEE
  • Journal of Display Technology publication information

    Page(s): C2
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    Freely Available from IEEE
  • Table of contents

    Page(s): 117 - 118
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  • Farewell Editorial

    Page(s): 119
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    Freely Available from IEEE
  • Ultra-High Transmission Electrowetting Displays Enabled by Integrated Reflectors

    Page(s): 120 - 122
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (510 KB) |  | HTML iconHTML  

    A reflector technique for increasing the transmission performance of a back-lit electrowetting display is presented. The electrowetting display pixel structure consists of an opaque oil film that blocks light transmission. Electrowetting with 5-10 V breaks up the oil film and creates a transmissive area for the pixel. With real-world electrowetting materials and device constraints, the transmissive area typically reaches 60% to 80% of the pixel area. By integrating a simple thin-film reflector between the backlight and the remaining oil film area, the effective transmission can be boosted to >90%. This high efficiency is promising for battery-powered applications and for high-brightness sunlight-legible displays. View full abstract»

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  • A Novel Advanced Wide-View Transflective Display

    Page(s): 123 - 128
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1397 KB) |  | HTML iconHTML  

    A novel wide-view transflective display has been developed. This kind of display has a high contrast wide-viewing angle with no grey level inversion by using the multidomain vertical alignment technology, and adequate reflectance with simple structure by using a novel advanced transflective technology. View full abstract»

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  • Wide-View and Broadband Circular Polarizers for Transflective Liquid Crystal Displays

    Page(s): 129 - 138
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3048 KB) |  | HTML iconHTML  

    A simple wide-view and broadband circular polarizer comprising of a linear polarizer and two uniaxial films is proposed to enhance the viewing angle of transflective liquid crystal displays (LCDs). For the transmissive mode, over the entire 90deg viewing cone, the normalized light leakage from two stacked circular polarizers is suppressed to below 1.5times10-2, and contrast ratio over 10:1 is obtained using a normally black vertically aligned transflective LCD. At the same time, this configuration warrants a broadband operation and reasonably good viewing angle (10:1 contrast ratio is over 40 at all directions) for the reflective mode. The physical mechanisms for achieving broadband operation and wide viewing angle are discussed. View full abstract»

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  • Dynamic Backlight Gamma on High Dynamic Range LCD TVs

    Page(s): 139 - 146
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1539 KB) |  | HTML iconHTML  

    A high dynamic range liquid crystal display (HDR-LCD) can enhance the contrast ratio of images by utilizing locally controlled dynamic backlight. We studied the HDR-LCD as a dual-panel display: a backlight module and a liquid crystal (LC) cell. As the gamma of the LC signal, the backlight module was also endowed with a gamma function to control the contrast ratio of HDR images. The inverse of a mapping function (IMF) method proposed as a dynamic gamma mapping curve for the backlight module, has been demonstrated to further improve in HDR image quality. By implementing the IMF method on a HDR-LCD TV with 88 backlight zones, the image contrast ratio can reach while maintaining high brightness, clear image detail, and an average power reduction of 30%. View full abstract»

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  • Tandem Light-Guides With Micro-Line-Prism Arrays for Field-Sequential-Color Scanning Backlight Module

    Page(s): 147 - 152
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (829 KB) |  | HTML iconHTML  

    An optically partitioned backlight system consisting of tandem wedge-shaped light-guides (LGs) with micro-line-prism arrays was developed for scanning field-sequential-color (FSC) liquid crystal display (LCD) in large size. The unit of wedge-shaped LG combined with a light-emitting diode (LED) light-bar was designed and fabricated to collimate the extraction light within a narrow angular extent. Based on the edge lighting approach, the volume of backlight system can be reduced down to 25 mm without sacrifice of the optical behavior. As a result, 2750 nits average luminance subject to 50% duty cycle and 83% uniformity can be achieved. The leakages into the consecutive adjacent blocks were well suppressed to 11.86%. View full abstract»

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  • Effects of Backlight Profiles on Perceived Image Quality for High Dynamic Range LCDs

    Page(s): 153 - 159
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2505 KB) |  | HTML iconHTML  

    Locally dimmable backlight modules can effectively improve the dynamic range of liquid-crystal displays (LCDs) to human vision range. The resolution of addressable segments and the optical profile of these segments primarily determine the perceived image quality such as the contrast enhancement and boundary visibility. Contrast sensitivity function, the gradient of backlight image of of background luminance (units: nits/degree), was found as the threshold for the visibility of boundaries. Additionally, a study on a recommended profile with an economical number of segments was studied. Our results confirm that image qualities with this backlight modulation are improved in contrast enhancement and boundary perception using 2D-dimming backlight. View full abstract»

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  • Plasma Modification of Fluoropolymers for Aligning Liquid Crystals

    Page(s): 160 - 165
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (930 KB) |  | HTML iconHTML  

    In this paper we describe methods to control liquid crystal (LC) alignment using plasma discharge on ferroelectric fluoropolymers. Two different plasma modification techniques were investigated: corona discharge and RF plasma in Ar gas. Corona discharge is a proven technique known to reorient the dipoles in poly (vinylidene fluoride) and its copolymers resulting in a strong remnant polarization. The polarization was patterned resulting in preferential LC alignment in selected regions. RF plasma in Ar gas defluorinates the polymer surface leading to planar alignment of positive dielectric anisotropy LCs. The defluorination of the alignment layer also causes low voltage switching of the LC. View full abstract»

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  • Trapezoidal and Triangular Waveform Profiles for Reducing Power Dissipation in Liquid Crystal Displays

    Page(s): 166 - 172
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1247 KB) |  | HTML iconHTML  

    We propose to replace the rectangular select pulses in all the conventional addressing techniques with either trapezoidal or triangular select waveforms to reduce the power dissipated in rms responding liquid crystal displays. A realistic analysis that includes the distortion in the addressing waveforms is presented for trapezoidal, triangular profiles, as well as their equivalents in discrete domain viz. the multi-step profiles and the results are compared. Good brightness uniformity among pixels that are driven to same state is achieved as a spinoff of the analysis and application of a correction voltage at the end of the select pulses. Increase in hardware complexity and the cost is minimal because just the voltage level generator circuit is modified to achieve reduction in power dissipation with new waveform profiles. View full abstract»

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  • Characterizing Fluorine-Ion Implant Effects on Poly-Si Thin-Film Transistors With {\hbox {Pr}}_{2}{\hbox {O}}_{3} Gate Dielectric

    Page(s): 173 - 179
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1141 KB) |  | HTML iconHTML  

    The fluorine ion implantation applied to the polycrystalline silicon thin-film transistors (poly-Si TFTs) with high-k Pr2O3 as gate dielectric is investigated for the first time. Using the Pr2O3 gate dielectric can obtain a high gate capacitance density and thin equivalent-oxide thickness, exhibiting a greatly enhancement in the driving capability of TFT device. Introducing fluorine ions into the poly-Si film by fluorine ion implantation technique can effectively passivate the trap states in the poly-Si film and at the Pr2O3/poly-Si interface to improve the device electrical properties. The Pr2O3 TFTs fabricated on fluorine-implanted poly-Si film exhibit significantly improved electrical performances, including lower threshold voltage, steeper subthreshold swing, higher field-effect mobility, lower off-state leakage current, and higher on/off current ratio, as compared with the control poly-Si Pr2O3 TFTs. Also, the incorporation of fluorine ions also improves the reliability of poly-Si Pr2O3 TFTs against hot-carrier stressing, which is attributed to the formation of stronger Si-F bonds. Furthermore, superior threshold-voltage rolloff characteristic is also demonstrated in the fluorine-implanted poly-Si Pr2O3 TFTs. Therefore, the proposed scheme is a promising technology for high-performance and high-reliability solid-phase crystallized poly-Si TFT. View full abstract»

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  • An Analytical Model Based on Surface Potential for a-Si:H Thin-Film Transistors

    Page(s): 180 - 187
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (675 KB) |  | HTML iconHTML  

    In this paper, an analytical a-Si:H thin-film transistor (TFT) model based on surface potential is presented. Firstly, an explicit approximation for the surface potential as a function of terminal voltages is proposed. In the new analytical solution, simultaneously, the effects of localized trapped charges and free carriers are considered. Moreover, the complex iterative computation is eliminated in the solution. Comparing with the numerical results, the proposed solution shows a high accuracy for predicting the surface potential under various biases. Secondly, a charge sheet model is then developed for the analysis of DC characteristics of a-Si:H TFT. The improved model can describes all operation regions via an unique formula and it is verified by a reasonable agreement between the simulated results and the experimental data. View full abstract»

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  • A Multi-Pass True Motion Estimation Scheme With Motion Vector Propagation for Frame Rate Up-Conversion Applications

    Page(s): 188 - 197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2320 KB) |  | HTML iconHTML  

    This paper presents a robust true motion estimation algorithm, designated as MPMVP (Multi-pass and Motion Vector Propagation), to enhance the accuracy of the motion vector fields in frame rate up-conversion applications. The MPMVP uses a multi-pass scheme to progressively refine approximate motion vectors to true motion vectors based upon the motion information acquired in previous passes. The multi-pass motion estimation process uses a large block size to detect the motion vectors within the objects themselves and small block sizes to detect the motion vectors along the object boundaries. Actually, the block size is progressively reduced during the search process. When the motion vector of a block is considered to be sufficiently accurate for motion estimation purposes, the block is said to be converged and the local motion vector search process terminates. A novel technique, referred to as motion vector propagation, is then applied to propagate the motion vector of the converged block to its neighboring blocks. This technique not only ensures that neighboring motion vectors within the same object have a high degree of spatial correlation, but also accelerates the convergence of the motion vectors in the neighboring blocks and therefore reduces the overall computational time and expense of the multi-pass motion vector search procedure. A novel distortion criterion is proposed to enhance the tolerance of the traditional sum-of-absolute-difference measurement technique applied in the motion estimation scheme to noise and shadow effects. The experimental results demonstrate that the proposed true motion estimation algorithm outperforms the traditional full search, 3DRS and TCSBP algorithms in terms of both the smoothness of the generated motion vector fields and the visual quality of the up-converted frames. View full abstract»

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  • Active and Adaptive Charging Method on Data Lines for Delay Compensation

    Page(s): 198 - 203
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    Charging time is a critical constraint in the design of large-size or high-resolution liquid crystal display. A fast charging method is proposed to generate adaptive charging voltages by comparing the pixel values between previous and current frames. Data line segmentation is also proposed to charge different subpixels on the data line precisely, which is implemented by using operational amplifiers and resistor networks. View full abstract»

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  • Power Dissipation in Multi-Line Addressed Liquid-Crystal Displays

    Page(s): 204 - 210
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (321 KB) |  | HTML iconHTML  

    Power dissipation in the driver circuit of liquid-crystal display is analyzed when the display is scanned with a multi-line addressing (MLA) technique that is based on Rademacher functions. We have considered the binary addressing technique (BAT), hybrid addressing technique (HAT), and improved HAT (IHAT) to obtain, the extreme as well as the average, power dissipation in the driver circuit. Closed-form expression for power dissipation is also obtained for these techniques; when the number of transitions in the addressing waveforms is forced to be independent of the state of the pixels by introducing duty cycle in select and data pulses. An improvement in the brightness uniformity can be achieved among pixels that are driven to the same state without increasing the average power dissipation by introducing duty cycle in the addressing waveforms. View full abstract»

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  • Charge Recycling Method on Pixel Level

    Page(s): 211 - 217
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (351 KB) |  | HTML iconHTML  

    A new power-saving design using charge recycling technique on the pixel level is proposed. Design constraints are derived and design examples are demonstrated. Compared with conventional charging methods, this method consumes only half the power, the charging speed is faster and the aperture ratio is similar. View full abstract»

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  • Motion Compensated Deinterlacing With Efficient Artifact Detection for Digital Television Displays

    Page(s): 218 - 228
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1183 KB) |  | HTML iconHTML  

    Deinterlacing is a scanning-format conversion technique that can convert interlaced pictures to progressive ones. Progressive televisions or monitors intended for displaying conventional interlaced programs have to apply deinterlacing techniques as required. Motion adaptive deinterlacing has been used widely in various kinds of commercial products, but the picture quality in motion areas still has much room for improvement. Motion compensated deinterlacing solves this problem by interpolation along the motion trajectory and thus is becoming the main trend of the next generation of deinterlacing algorithms. However, it suffers visible artifacts caused by incorrect motion vectors. To improve such imperfect pictures, this paper presents a motion compensation algorithm with more accurate motion estimation and more efficient artifact detection for digital television displays. Soft-switching between intra and inter interpolations is realized by characterizing different areas of the picture. Simulation results indicate that the proposed scheme can produce high-quality pictures with less flicker and imperceptible artifacts than a number of other techniques that were tested. In particular, the simulated peak signal-to-noise ratio (peak SNR) is basically 3-10 dB better than a comparable and prominent deinterlacing method. View full abstract»

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  • A Testing Method on Poly-Si Thin-Film Transistor Array for Active-Matrix Organic Emitting Display

    Page(s): 229 - 232
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    A novel method is introduced using to evaluate the quality of thin-film transistor (TFT) array for driving active-matrix display (OLED). By the means of this method, the operation states of the TFT or the defects of TFT can be judged. It is a current testing method with the advantages of fast response, excellent precision, no effect to aperture and no damage to the display array. View full abstract»

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  • Low-Power Low-Cost Voltage-Programmed a-Si:H AMOLED Display for Portable Devices

    Page(s): 233 - 237
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (607 KB) |  | HTML iconHTML  

    This paper presents a driving scheme to achieve highly stable low-power amorphous silicon (a-Si:H) active-matrix organic light-emitting diode (AMOLED) displays. Although the conventional 2-thin-film transistor (TFT) a-Si:H AMOLED display has demonstrated interesting features, including simplicity, it is prone to growing nonuniformity due to the temporal instability of the a-Si:H material. Several compensating techniques have been proposed to control the nonuniformity, but they tend to compromise the key attributes of the simple 2-TFT display such as low power consumption, high yield, high aperture ratio, low implementation cost, and fast programming. For mobile applications which have tight constrains on power consumption, cost, and escalating resolution requirements, we propose a new driving and addressing scheme that not only improves the backplane stability, but also compensates for the OLED luminance degradation while maintaining the attractive features of the simple 2-TFT pixel circuit. The overhead in power consumption and implementation cost is reduced by over 90% compared to existing compensation driving schemes. View full abstract»

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  • A Study on the Measurement Technique of Image Retention in AC Plasma Display Panels

    Page(s): 238 - 244
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1275 KB) |  | HTML iconHTML  

    A technique for quantitatively measuring the image retention is suggested. This work focuses on dark image retention, which occurs during the reset period. To investigate the dark image retention phenomenon, characteristics of reset discharge were observed in accordance with the slope of the reset pulse. The temporal behaviors of luminance, chromatistic values, and infra red emission were observed with the black-level image after a five-minute repeatedly strong discharge. The image retention time of the luminance and chromatistic values increased with a decrease in the rising time of the reset ramp pulse. For the case of infrared (IR) emission, there was no clear tendency, in contrast with the image retention or temporal image sticking phenomenon. The results indicate that measurement of the temporal behaviors of luminance and chromatistic values provide suitable measurement for investigating the image retention in AC plasma display panels (PDPs), whereas the IR emission does not provide a useful guide in this regard. View full abstract»

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  • Simulation of Active-Matrix Electrophoretic Display Response Time Optimization by Dual-Gate a-Si:H TFT With a Common Gate Structure

    Page(s): 245 - 249
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (569 KB) |  | HTML iconHTML  

    Large off-state drain-source current of the thin-film transistor (TFT) in active-matrix electrophoretic display (AMEPD) pixel leads to dramatic data voltage degradation, which causes severe crosstalk and undesired large response time. In this paper, the leakage current influence on response time is investigated and simulated. A compact model of response time t versus off-state drain-source current I off is established. The simulation result induces that by reducing I off the response time can be efficiently shorted. In order to reduce the off-state current, dual-gate amorphous silicon (a-Si:H) TFT with a common gate structure is discussed. Its current regulation mechanism is illustrated, and its fitness for driving the AMEPD pixel is explained. The SPICE simulation results prove that except reducing the crosstalk, dual-gate a-Si TFT can also significantly short the response time by cutting down the off-state current under the operation conditions of AMEPD application, while insignificantly reduces the on-state current. View full abstract»

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  • Multilayer Dielectric Color Filters for Optically Written Display Using Up-Conversion of Near Infrared Light

    Page(s): 250 - 253
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (597 KB) |  | HTML iconHTML  

    An optically written display based on up-conversion of near-infrared light is a newly emerging display technology. For filtering out unwanted colors from this light generator, multilayer dielectric color filters are designed for red, green, and blue screens, respectively. Layer-symmetric films are used in the designed filters and the conjugate gradient method is used to optimize the design. It is observed that the characteristics of the filters are good in the whole visible wavelength range when the incident angle is less than 40deg. The encompassed color triangle of the display with the color filters is larger than that without the color filters, and images with more saturated colors are obtained. View full abstract»

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  • A Projection System for Real World Three-Dimensional Objects Using Spatial Light Modulators

    Page(s): 254 - 261
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1484 KB) |  | HTML iconHTML  

    We discuss a projection system for real world three-dimensional objects using spatial light modulators (SLM). An algorithm to encode the digital holograms of real world objects on to an SLM is presented. We present results from experiments to project holograms of real world holograms using a nematic liquid crystal SLM. We discuss the case when the pixel sizes of the charge-coupled device (CCD) and SLM used for recording the hologram and projection are different. View full abstract»

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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.