Dissertations / Theses on the topic 'Microdisplays'

<p>Organic Light Emitting Displays (OLEDs) are a new type of thin emissive displays predicted to possess superior properties to existing techniques e.g. Liquid Crystal Display (LCD). The main advantages are low power consumption and a thin display structure. This report contains an explanation of the emissive OLED technology, its functionality and the physics of the organic layer structure in an OLED. The technology is described with respect to the two classes of organic materials used in displays, small molecules and conjugated polymers. </p><p>The information is derived from a study of literature and from different measurements performed on a full-colour OLED microdisplay, based on colour filters. The evaluation of the OLED revealed the main disadvantage of an unsatisfactory lifetime of approximately only one week. The results of the measurements and study are furthermore compared to the traditional LCD technology. </p><p>A conclusion with the advantages and drawbacks with the OLED technology summarises the report together with a short analysis of the future for OLEDs, partly achieved through a written enquiry sent to approximately 20 possible OLED manufactures.</p>

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.<br>Includes bibliographical references (leaves [61]-[65]). Also available in electronic version. Access restricted to campus users.

Applications using liquid crystal on silicon (LCoS) spatial light modulators (SLM) demand a high level of device flatness. The overall backplane and individual mirror flatness directly influences SLM optical quality in a number of interrelated ways. They affect the liquid crystal (LC) cell gap uniformity, optical efficiency and LC alignment characteristics directly. In turn, the LC thickness variation and alignment quality affects device contrast ratio. The final cell gap uniformity, and LC alignment quality are also influenced by surface morphology, and by the chemistry of the surface over which the LC flows during cell filling. It is therefore critical to minimise the surface morphology and have a good understanding as to the LC's interaction with the surface over which it flows. Chemical mechanical polishing (CMP) can be used to increase device flatness and reduce the problems associated with surface morphology. A technique to remove the layout and process dependent surface topography using CMP has been investigated. Problems were initially encountered due to the presence of the large, feature dense, pixel array. These were overcome by the development of a novel pre-CMP dielectric etch step, resulting in a greatly improved post-CMP dielectric uniformity and a sub-nanometer RMS surface finish. Conventional planarisation techniques leave the mirrors standing proud of the surrounding dielectric surface. Two methods of reducing this mirror step-height have been compared, namely mirror damascene and via-damascene. The mirror-damascene method resulted in mirrors that are co-planar with the dielectric surface. While this improved the LC flow uniformity during cell filling, it introduced new concerns such as mirror dishing and array erosion. A more attractive technique is that of via damascene which produces vias that are level with the dielectric surface. This approach allows the deposition of thin high quality aluminium mirrors. Initial problems were encountered with via dishing and CMP induced dielectric degradation; both of which were addressed using a post-damascene dielectric buff.

La travail présente traite du développement de diodes organiques électroluminescentes(OLEDs) a haute luminance pour des applications dans des micro écrans. Ces dispositifs sontbases sur des substrats silicium utilisent la technologie CMOS. Le présent ouvrage met en avantles efforts développe afin de réduire la dérive en tension et ma décroissance lumineuse enopération des dispositifs lumineux.Dans la première partie de l’étude, des OLEDs vertes haute luminance fonctionnant àbasse tension sont développes. L’empilement organique a émission vers le haut comprenant unémetteur fluorescent vert entre des couches de blocage de charges et des couches de transportdopées. Les effets de différentes structures de dispositifs, des configurations de l’empilement etdes matériaux organiques sur les performances initiales et en opération sont reportés ici.Dans la deuxième partie de l’étude, le développement de dispositifs OLED hybrides pourmicro écrans couleurs est présenté. Les structures hybrides comprennent une couche detransport de trous photosensible et traitable par solution (X-HTL) et d’une OLED blancheréalisée par évaporation sous vide. Cette méthode permet la génération de couleur directe, ellepermet ainsi d’obtenir de très bonnes efficacités et un contrôle aisé de la couleur émise parsimple modification de l’épaisseur de X-HTL<br>The present work reports the development of high luminance organic light emitting diodes(OLEDs) device stacks for microdisplay applications. The devices are based on siliconcomplementary metal-oxide semiconductor (CMOS) backplane. In the present treatise effortsare particularly focused on reducing the luminance decay and the voltage drift during deviceoperation.In the first part of this study, high brightness and low operating voltage green OLEDs arereported. The top emitting device stack comprises of fluorescent green emitter accompanied bycharge blocking layers and doped charge transport layers. The effect of different devicestructures, configurations and organic materials on the initial and lifetime performance of thedevice is presented.In the second part of the study, device development of hybrid OLED stacks for high luminancefull color microdisplays is reported. The hybrid devices comprise of a solution processed andphotocrosslinkable hole transport layer (X-HTL) and an evaporated white OLED stack. Thismethod allows direct primary color generation with relatively high efficiency and offers ease ofcolor tunability by controlling the thickness of the X-HTL

Ce travail porte sur la réalisation d'un micro-écran OLED haute luminance sur silicium. L'efficacité limitée des structures WOLED associées à des filtres colorés est un frein au développement de cette technologie pour des applications dans des dispositifs de type « see-through ». Nous proposons une approche tirant parti de l'effet de microcavité optique présent dans les écrans OLED à émission vers le haut pour générer des couleurs sans filtres. Les modulations de cavité à l'échelle du sous-pixel étant assurées par l'insertion d'oxyde transparent conducteur entre l'anode et l'OLED.L'étude offre selon un raisonnement cohérent de suivre les différentes phases de la réalisation d'un démonstrateur de ce type. Seront abordées dans la première partie les étapes technologiques de structuration de l'oxyde à l'échelle d'un sous-pixel de 16µm². Nous traiterons ensuite du développement d'un empilement OLED tandem utilisant des émetteurs fluorescent et phosphorescents. Une approche par simulation optique sera utilisée pour l'optimisation de cette architecture à un fonctionnement sur microcavité. Puis la discussion autour de la mise en commun des blocs technologiques précédents permettra d'aborder des écueils spécifiques au micro-écran OLED et de proposer des pistes de résolution<br>This study focuses on the realization of a high brightness OLED micro-écran on silicon. The limited efficiency of White-OLED combined with color filters prevents the use of this technology in “see-through” applications. We propose a novel approach getting benefits from the optical micro-cavity effect in Top-Emitting OLED to generate colors without using color filters. Cavity modulations at a sub-pixel scale are realized by using a Transparent Conducting Oxide between the anode and the OLED.Following a step-by-step reasoning the work offers to follow all the phases of the realization of a prototype using this principle. In the first part, the technological steps of the processing of oxide cavities with a surface of 16µm² will be discussed. Then we will work on the development of a tandem OLED structure using both fluorescent and phosphorescent emitters optimized for micro-cavities. To this end optical simulation will be used. The two technological blocs will finally be put together to enlighten some issues specific for micro-écran technology and to give some clues to solve them

Ce travail se concentre sur le développement d’écrans miniatures OLED haute luminance. Utilisés dans des systèmes optiques proches de l’oeil de type « see through », ces dispositifs OLED requièrent des luminances dix fois plus importantes que celles des produits conventionnels.La génération des trois primaires à partir d’une OLED blanche à émission par le haut se faisant aux moyens de filtres colorés, une large partie de l’émission est absorbée puis perdue. Afin de s’affranchir de ces filtres, une première approche s’est orientée vers la modulation de la cavité optique de l’OLED. Cette approche aboutit à la génération directe de la couleur grâce à la variation de l’épaisseur de l’anode transparente, de type TCO, à l’échelle des sous-pixels.La seconde limitation repose sur l’extraction de la lumière au travers d’une cathode semi-transparente. L’effet de cavité ainsi introduit filtre et réduit les composantes émises. L’approche choisie s’est portée sur le développement d’une cathode transparente de type TCO combinée à une grille métallique assurant le couplage externe de l’émission de l’OLED.Après avoir identifié les matériaux et la technique de dépôt appropriés, l’évaluation des OLED intégrant lesdites électrodes a été faite. Le recours à la simulation optique ainsi qu’à la modélisation électrique des structures a permis de discuter des limitations des matériaux et des comportements aux interfaces. A l’issue de cette discussion, des pistes d’amélioration et des perspectives ont été proposées<br>This study focuses on the development of high brightness OLED microdisplays based on active matrix (AMOLED). Because these devices are used into near-to-eye (NTE) applications and more precisely « see through » optical systems, high luminances are required. Compared to conventional microdisplays, the high luminances expected are around ten times higher.In order to emit a white spectrum from a top-emitting OLED (TE-OLED), color filters are mandatory to generate the RGB primaries. Nevertheless, by using these filters, the luminance is dramatically reduced because of the light absorption. Therefore, to be free of the filters, a first study is dedicated to the modulation of the optical cavity of the OLED. In this case, the direct generation of the colors is provided by the variation of the TCO anode thickness.The cavity effect observed into the TE-OLED depends on the semi-transparent cathode. The selectivity of the related cavity represents the bottleneck for emitting broad white spectra. To improve the white emission, a second approach deals with the realization of a TCO cathode coupled with a metallic grid.The appropriated materials and deposition techniques were firstly investigated before the characterization of OLED using a transparent anode to modulate the cavity in one hand and a transparent cathode to increase the light emission in another hand. Optical simulations and electrical modelling were employed to highlight the main behaviors driving these OLED. Following a discussion about the strength and the weakness of each structure, some hints of improvement were given

碩士<br>國立交通大學<br>光電工程研究所<br>107<br>There is a huge variety of AR glasses in the market recently. However, each type of AR glasses can only fit in some specific niche application. The reason why that the diversity of AR glasses exists is that different AR application scenarios request different form factor, such as ID design and content display. Technology nowadays just cannot meet all the different situation needs with a single model. 　In order to solve this problem, an off-axis optical architecture with single microdisplay is proposed in this study. The concept of this experiment is to add AR display function to currently exists glasses without changing its form factor and ID design with minimizing extra weight loading. Due to the very little space between face and the glasses, inserting optical light path can be hard. We make the major extra weight be added over nose and ear, where direct support is underneath. 　The sport glasses chosen for the prototype is a ski goggle provided by Argus Vision. A free-form surface is chosen for optical component use. To reduce the eye relief and increase the field of view through the configuration of the optical architecture, in which only single display panel is used for both views. Although the resolution has to be diminished into half for each view, it still sufficient for sporting application scenarios, such as heart beating rate, blood sugar, PM2.5, and direction pointing arrow. Finally, we successfully develop a prototype of glasses through ultra-precision machining.

碩士<br>大同大學<br>通訊工程研究所<br>95<br>Development of applications of mobile phone has entered the era of personal digital terminal, not just only as voice communication equipment. Concept of TV on mobile phone makes mobile TV as the next killer application of mobile phone after camera phone. The paper introduces the main stream of standard of digital broad casting for handheld terminal, DVB-H. The entertainment effect of mobile TV will be reduced due to limited screen dimension; we propose a solution for mobile large screen, which is integrating LCoS Microdisplay as an external display system for mobile phone DVB-H application. In first stage, we study the display technology in existing mobile phone, and make a system which can convert the display format of mobile phone to NTSC signal by using FPGA as video data buffering and format transformer. The mobile large screen is accomplished by connecting the system with existing LCoS Microdisplay product which has NTSC interface. Then, we design a system to drive the existing VGA LCoS Microdisplay module directly, and the target is making a complete integration of external VGA LCoS Microdisplay and mobile phone DVB-H application.