3,684 research outputs found

    High Efficiency and Wide Color Gamut Liquid Crystal Displays

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    Liquid crystal display (LCD) has become ubiquitous and indispensable in our daily life. Recently, it faces strong competition from organic light emitting diode (OLED). In order to maintain a strong leader position, LCD camp has an urgent need to enrich the color performance and reduce the power consumption. This dissertation focuses on solving these two emerging and important challenges. In the first part of the dissertation we investigate the quantum dot (QD) technology to improve the both the color gamut and the light efficiency of LCD. QD emits saturated color and grants LCD the capability to reproduce color vivid images. Moreover, the QD emission spectrum can be custom designed to match to transmission band of color filters. To fully take advantage of QD\u27s unique features, we propose a systematic modelling of the LCD backlight and optimize the QD spectrum to simultaneously maximize the color gamut and light efficiency. Moreover, QD enhanced LCD demonstrates several advantages: excellent ambient contrast, negligible color shift and controllable white point. Besides three primary LCD, We also present a spatiotemporal four-primary QD enhanced LCD. The LCD\u27s color is generated partially from time domain and partially from spatial domain. As a result, this LCD mode offers 1.5× increment in spatial resolution, 2× brightness enhancement, slightly larger color gamut and mitigated LC response requirement (~4ms). It can be employed in the commercial TV to meet the challenging Energy star 6 regulation. Besides conventional LCD, we also extend the QD applications to liquid displays and smart lighting devices. The second part of this dissertation focuses on improving the LCD light efficiency. Conventional LCD system has fairly low light efficiency (4%~7%) since polarizers and color filters absorb 50% and 67% of the incoming light respectively. We propose two approaches to reduce the light loss within polarizers and color filters. The first method is a polarization preserving backlight system. It can be combined with linearly polarized light source to boost the LCD efficiency. Moreover, this polarization preserving backlight offers high polarization efficiency (~77.8%), 2.4× on-axis luminance enhancement, and no need for extra optics films. The second approach is a LCD backlight system with simultaneous color/polarization recycling. We design a novel polarizing color filter with high transmittance ( \u3e 90%), low absorption loss (~3.3%), high extinction ratio (\u3e10,000:1) and large angular tolerance (up to ±50˚). This polarizing color filter can be used in LCD system to introduce the color/polarization recycling and accordingly boost LCD efficiency by ~3 times. These two approaches open new gateway for ultra-low power LCDs. In the final session of this dissertation, we demonstrate a low power and color vivid reflective liquid crystal on silicon (LCOS) display with low viscosity liquid crystal mixture. Compared with commercial LC material, the new LC mixture offers ~4X faster response at 20oC and ~8X faster response at -20°C. This fast response LC material enables the field-sequential-color (FSC) driving for power saving. It also leads to several attractive advantages: submillisecond response time at room temperature, vivid color even at -20oC, high brightness, excellent ambient contrast ratio, and suppressed color breakup. With this material improvement, LCOS display can be promising for the emerging wearable display market

    Evaluation of the color image and video processing chain and visual quality management for consumer systems

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    With the advent of novel digital display technologies, color processing is increasingly becoming a key aspect in consumer video applications. Today’s state-of-the-art displays require sophisticated color and image reproduction techniques in order to achieve larger screen size, higher luminance and higher resolution than ever before. However, from color science perspective, there are clearly opportunities for improvement in the color reproduction capabilities of various emerging and conventional display technologies. This research seeks to identify potential areas for improvement in color processing in a video processing chain. As part of this research, various processes involved in a typical video processing chain in consumer video applications were reviewed. Several published color and contrast enhancement algorithms were evaluated, and a novel algorithm was developed to enhance color and contrast in images and videos in an effective and coordinated manner. Further, a psychophysical technique was developed and implemented for performing visual evaluation of color image and consumer video quality. Based on the performance analysis and visual experiments involving various algorithms, guidelines were proposed for the development of an effective color and contrast enhancement method for images and video applications. It is hoped that the knowledge gained from this research will help build a better understanding of color processing and color quality management methods in consumer video

    Sustainability Implications of Consumer Electronics Adoption in the United States

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    High rates of technological innovation and consumer adoption in the consumer electronics sector has led to increasing concerns about the potential implications on resource consumption and waste generation. Despite growing public and policy attention on recycling as a strategy to curb resource demand and waste management impacts, less than 50 percent of end-of-life electronics are recovered for recycling in the U.S. A critical barrier to sustainable management of electronics is the lack of data and tools to proactively estimate consumption and waste flows, to create solutions that respond to the dynamic nature of this product sector. For sustainable solutions to keep pace with the rapid rate of innovation, they must be informed by comprehensive and proactive research, that not only quantifies material flows in electronics but also investigates associated economic, environmental and social implications. This dissertation aims to fill this knowledge gap through three interconnected lines of inquiry. First, a baseline material footprint analysis is conducted to retroactively estimate the material consumption and waste generation associated with household electronic product consumption in the U.S. from 1990 until present. Results from this analysis contradict the long-standing assumption that e-waste is a rapidly growing waste stream in the U.S. In fact, the net material footprint of electronics has begun to decline, mainly due to consumers phasing out large Cathode Ray Tube TVs in favor of lighter flat panel technologies. While the analysis shows decline in potential e-waste toxicity from traditional hazards like lead and mercury, it also raises new issues of concern for e-waste management. Notably, results show high resource potential in the emerging e-waste stream with new opportunities to recover scarce metals not currently recycled. Second, a predictive material flow model based on historic product adoption behavior was developed, to enable future forecasts of resource and waste flows so that stakeholders can create proactive – rather than reactive – solutions. Adoption forecasts for emerging technologies show increasingly fast windows of product innovation and uptake. In other words, new electronics are likely to have rapid uptake in the market but may be quickly replaced by subsequent product innovations. The forecasts also suggest that waste flows for mature products like CRTs, desktops, monitors and flat panel TVs will continue to be a major issue for the short term, with declining contribution to the U.S. e-waste stream in the future. Material flow estimations predict increasing prevalence of critical materials in e-waste underscoring a need to shift e-waste management mechanisms from ‘mass’ to ‘materials’, or in other words, from an emphasis on ‘waste diversion’ to a new focus on ‘resource retention’. Finally, a comprehensive set of sustainability metrics were created and applied to assess the economic, environmental and social impacts for the wide spectrum of materials used in electronics. Material metrics help identify key material hotspots and prioritize new solutions for reducing resource demand and waste management challenges. This dissertation contributes novel data and modeling tools that can aid stakeholders across the electronics industry in making informed decisions in product design, policy planning and material recovery in electronics

    Phase-Change Meta-Devices for Tuneable Bandpass Filtering in the Infrared

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    Tuneable light filters, especially those which are compact and fast to tune, are essential in a wide range of technologies, especially for multispectral imaging applications. However, state-of-the-art approaches to create such filters all possess drawbacks, with many wavelength regions poorly served. This thesis attempts to address this problem by combining metasurfaces which support extraordinary optical transmission (ultra-thin band-pass filters) with chalcogenide phase-change materials (adding dynamic tuneability). The optical properties of phase-change materials are very different in their amorphous and crystalline states and switching between such states can be rapidly controlled via thermal excitations. In this work nine different phase-change materials, including alloys of GeTe, GeSbTe, GeSbSeTe and GaLaS, were optically and elementally characterised and assessed for their application-specific suitability. The resulting materials data was used to computationally design and evaluate a range of tuneable infrared filter device designs both optically and thermally. These filters exhibit high transmission (≈80% at best) with large spectral tuning ranges of approximately +50% relative to their shortest wavelength; this range is sufficient to cover entire atmospheric transmission windows. This is the first such combination of phase-change materials and extraordinary optical transmission for application from the visible through to long-wave infrared (14 μm) regions of the spectrum. A rigorous computational study was conducted to produce comprehensive design guidelines for such filters, and confirm the viability of in-situ electrical switching. Several filter devices were experimentally fabricated, and the viability for a number of applications, including tuneable filtering, chemical sensing and infrared displays, was investigated and confirmed computationally.Engineering and Physical Sciences Research Council (EPSRC

    JTEC panel on display technologies in Japan

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    This report is one in a series of reports that describes research and development efforts in Japan in the area of display technologies. The following are included in this report: flat panel displays (technical findings, liquid crystal display development and production, large flat panel displays (FPD's), electroluminescent displays and plasma panels, infrastructure in Japan's FPD industry, market and projected sales, and new a-Si active matrix liquid crystal display (AMLCD) factory); materials for flat panel displays (liquid crystal materials, and light-emissive display materials); manufacturing and infrastructure of active matrix liquid crystal displays (manufacturing logistics and equipment); passive matrix liquid crystal displays (LCD basics, twisted nematics LCD's, supertwisted nematic LCD's, ferroelectric LCD's, and a comparison of passive matrix LCD technology); active matrix technology (basic active matrix technology, investment environment, amorphous silicon, polysilicon, and commercial products and prototypes); and projection displays (comparison of Japanese and U.S. display research, and technical evaluation of work)

    Appearance-based image splitting for HDR display systems

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    High dynamic range displays that incorporate two optically-coupled image planes have recently been developed. This dual image plane design requires that a given HDR input image be split into two complementary standard dynamic range components that drive the coupled systems, therefore there existing image splitting issue. In this research, two types of HDR display systems (hardcopy and softcopy HDR display) are constructed to facilitate the study of HDR image splitting algorithm for building HDR displays. A new HDR image splitting algorithm which incorporates iCAM06 image appearance model is proposed, seeking to create displayed HDR images that can provide better image quality. The new algorithm has potential to improve image details perception, colorfulness and better gamut utilization. Finally, the performance of the new iCAM06-based HDR image splitting algorithm is evaluated and compared with widely spread luminance square root algorithm through psychophysical studies

    Expanding Dimensionality in Cinema Color: Impacting Observer Metamerism through Multiprimary Display

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    Television and cinema display are both trending towards greater ranges and saturation of reproduced colors made possible by near-monochromatic RGB illumination technologies. Through current broadcast and digital cinema standards work, system designs employing laser light sources, narrow-band LED, quantum dots and others are being actively endorsed in promotion of Wide Color Gamut (WCG). Despite artistic benefits brought to creative content producers, spectrally selective excitations of naturally different human color response functions exacerbate variability of observer experience. An exaggerated variation in color-sensing is explicitly counter to the exhaustive controls and calibrations employed in modern motion picture pipelines. Further, singular standard observer summaries of human color vision such as found in the CIE’s 1931 and 1964 color matching functions and used extensively in motion picture color management are deficient in recognizing expected human vision variability. Many researchers have confirmed the magnitude of observer metamerism in color matching in both uniform colors and imagery but few have shown explicit color management with an aim of minimized difference in observer perception variability. This research shows that not only can observer metamerism influences be quantitatively predicted and confirmed psychophysically but that intentionally engineered multiprimary displays employing more than three primaries can offer increased color gamut with drastically improved consistency of experience. To this end, a seven-channel prototype display has been constructed based on observer metamerism models and color difference indices derived from the latest color vision demographic research. This display has been further proven in forced-choice paired comparison tests to deliver superior color matching to reference stimuli versus both contemporary standard RGB cinema projection and recently ratified standard laser projection across a large population of color-normal observers

    Test Targets 7.0: A Collaborative effort exploring the use of scientific methods for color imaging and process control

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    Test Targets is a culmination of teaching and learning that reflects quality and analytic aspects of printing systems and their optimization. The creation of the Test Targets publication is a total experience that reflects the innovation, problem solving, and teamwork of the diverse team of faculty, staff, students, and professionals responsible for its contents and production
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