Display Resolution Research Articles

55‐2: Essential Mask Quality for High‐End Resolution Displays

This paper proposes a best practice to produce the photomasks with the state‐of‐the‐art quality, suitable for high resolution panel patterning. In order to extend the panel patterning process capability, high CD performance (Resolution, CD MTT and CD Uniformity) of photomask is essential and RET(Resolution Enhancement Technology) such as PSM, OPC and OAI will be prominent technology for mask business. PSM and OPC technology on RET will be new challenges for future high resolution panel. These challenges require new generation photomask writer, PSM manufacturing capability.

P‐114: White and Top‐Emitting Quantum‐Dot Light‐Emitting Diodes with Indium‐Tin‐Oxide Top Electrodes

Top‐emitting white quantum‐dot light‐emitting diodes (QLEDs) have great promise for the active‐matrix display applications because the light emitting from the top electrodes greatly increases the aperture ratio of the display, while by working with color filters, they could enable the realization of high resolution, large area and full color display. However, it is difficult to achieve white emission in a conventional top‐emitting structure due to the microcavity effect. In this work, we develop white and top‐emitting QLEDs by using indium‐tin‐oxide (ITO) as the top electrodes, which greatly alleviate the undesired microcavity effect. To enhance hole injection from bottom Al anode to the TFB hole transport layer, the double hole injection layers MoO3/PEDOT:PSS are utilized, and to protect the quantum dots (QDs) from damaging by the plasma, a compact electron transport layer based on ZnMgO:PVP composite is used. As a consequence, the demonstrated devices exhibit a high brightness of 12980 cd m−2, a pure white color with a 1931 Commission International de I’Eclairage (CIE) coordinate of (0.33, 0.33) and a high color stability. The demonstrated white and top‐emitting QLEDs, with high brightness and high color stability, would be ideal candidates for next generation active‐matrix display and solid‐state lighting applications.

77‐2: Anisotropic Nano‐Structure Light Control Film

The Anisotropic Nano‐Structure Light Control Film was produced through the combination of Nano‐Structure Thin film and anisotropic molecular. With alignment of anisotropic molecular, light with different polarization exhibits different optical behavior, transparent or scattering. With such optical properties, the anisotropic nano‐structure light control film could be applied to enhance the visibility of transparent display, picture quality of high resolution display and ultra‐slim design,

23‐3: Distinguished Paper: The New Route for Realization of 1µm‐pixel‐pitch High Resolution Displays

We present a new pixel structure to realize the 1μm‐pixel‐pitch display. This structure is based on the conventional back‐channel etched thin‐film transistor (TFT), but all layers except the horizontal gate line are vertically stacked on the embedded data line, enabling the implementation of high resolution display panels. The vertically‐stacked TFT with 1μm‐channel length shows a high field effect mobility over 50 cm2/Vs, low subthreshold slope of 78 mV/decade. It also shows a high uniform electrical characteristic over the entire 6‐inch wafer. The development of new architecture enables the implementation of a 1μm‐pixel‐pitch high resolution displays such as digital hologram.

Improving near-eye display resolution by polarization multiplexing.

We present here an optical approach to boost the apparent pixel density by utilizing the superimposition of two shifted-pixel grids generated by a Pancharatnam-Berry deflector (PBD). The content of the two shifted pixel grids are presented to the observer's eye simultaneously using a polarization-multiplexing method. Considering the compact and lightweight nature of PBD, this approach has potential applications in near-eye display systems. Moreover, the same concept can be extended to projection displays with proper modifications.

A high-dynamic range CMOS camera based on dual-gain channels

To overcome the ghosting phenomenon of multi-exposure technology, a new high-dynamic range (HDR) image processing method is proposed in this paper, which combines the features from dual-gain channel images. Further, a complete CMOS camera based on the HDR method is implemented, which produces a real-time HDR live video streams. This camera can capture the details of bright and dark areas in the scene completely with an extended dynamic range up to 95 dB. An ALTERA FPGA is the core processing unit of the entire camera, and it completes all the functional modules of the camera efficiently, including dual-channel video capture, image caching, HDR synthesis and tone mapping. Finally, the real-time HDR video flow has a display resolution of 1920 × 1080 and a frame rate of 60 fps.

(Invited) High-Frequency Operation of Vertical Organic Field-Effect Transistors

Organic thin-film transistors (OTFT) are attracting great interest in view of flexible electronics enabling future revolutionizing applications such as flexible displays or wearable electronics. Due to the poor intrinsic charge carrier transport in organic semiconductor thin-films, the main target of development in the last two decades was to find suited semiconductor materials offering a higher charge carrier mobility. However, although record values of clear beyond 10cm²/Vs have been demonstrated, key transistor parameters such as the transconductance or transition frequency have not been improved substantially. In consequence, the performance of today's OTFTs is still too low for many demanding electronic applications. In the last couple of years we have develop various architectures for vertical organic transistor offering superior current driving capabilities compared to state-of-the-art horizontal organic TFTs. Within this 3-dimensional VOFET geometry, the channel length is not defined by the applied patterning technique but rather by the thickness of the organic layers, typically <300nm, separating the vertically stacked source and drain electrodes. This ultra-short channel configuration allows for superior current driving, however, it is usually accompanied by undesired short-channel effects such as loss of saturation and an increased off-current level. In my presentation I introduce the VOFET concept and highlight the development of optimized transistor geometries leading to superior performance with an on/off ratio>10⁷, transition frequency approaching 100MHz and excellent operational stability. In the second part of the contribution I focus on the potential of VOFETs for active matrix OLED (AMOLED) display driving. Comparing typical TFT design guidelines for vertical and horizontal TFTs, it can be deduced that the VOFET design leads to a considerable reduction of area consumption within a pixel which ultimately enables a higher display resolution and a lower power consumption. The concept of vertical transistors is not restricted to organic semiconductors. Hence, I discuss in the third part of my presentation the potential of high mobility metal-oxide semiconductors for vertical thin-film transistors for GHz operation.

Microlens Arrays above Interlaced Plasmonic Pixels for Optical Security Devices with High‐Resolution Multicolor Motion Effects

AbstractOptical security devices based on high‐density microlens arrays on top of printed microimages or interlaced patterns can display high‐resolution image frames with attractive motion effects. However, the effects are so far restricted to a single color due to challenges in printing multiple colors with sufficiently high resolution and precision. This article introduces a viable solution based on microlens arrays above plasmonic colors to enable high‐resolution multicolor image frames with multidirectional motion effects. Plasmonic color pixels comprised of metalized nanowell arrays are implemented to print 2D interlaced patterns with super‐high resolution and nanoscale precision. Using a 2D microlens array of 25 µm lens pitch, 50 color image frames are obtained from a plasmonic color pattern printed with resolution of 10 160 dots per inch. The image frames show multiple colors, which significantly boost the color performance of microlens‐based security devices. The display resolution of image frames reaches 1016 pixels per inch, which is at least six times higher than conventional lenticular images. The color image frames also show excellent motion effects when moving the view point along any arbitrary direction. The presented devices can be advantageous for commercial applications in security, authentication, and product branding.

Effects of ray position sampling on the visual responses of 3D light field displays.

A 3D light field display typically reconstructs a 3D scene by sampling either the projections of the 3D scene at different depths or the directions of the light rays apparently emitted by the 3D scene and viewed from different eye positions. These light field display methods are potentially capable of rendering correct or nearly correct focus cues and therefore addressing the well-known vergence-accommodation conflict problem plaguing the conventional stereoscopic displays. However, very limited efforts have been made to investigate the effects of light ray sampling on the quality of the rendered focus cues and thus the visual responses of a viewer in light field displays. In this paper, by accounting for both the specifications of a light field display system and the ocular factors of the human visual system, we systematically model and analyze the ray position sampling issue in the reconstruction of the light field and characterize its effect on the quality of the rendered retinal image and on the accommodative response in viewing a 3D light field display. Using a recently developed 3D light field display prototype, we further experimentally validated the effects of ray position sampling on the resolution and accommodative response of a light field display, of which the result matches with theoretical characterization.

Demonstration of an improved integral imaging system with large viewing angle using the micro-lens array mask

An improved integral imaging system with large viewing angle using the micro-lens array mask (MLAM) is demonstrated. Currently, the limitation of viewing angle is one of primary defects of the conventional integral imaging (InIm). Here, a novel MLAM is designed and fabricated to eliminate this limitation, and a mapping relationship of coding is presented to guarantee the perceived 3D image with correct occlusion relation. The viewing angle of the proposed InIm-improved system are significantly improved without decreasing the spatial display resolution of the displayed 3D images. In the experiment, a demonstrated prototype system using the MLAM and a 23.6-in. liquid crystal display (LCD) panel with the resolution of 3840 × 2160 is realized with 45° viewing angle, which can provide a natural 3D visual effect with high quality.

Pitch-Synchronous Analysis of Human Voice

Based on simultaneous voice and electroglottograph (EGG) signals, to gain a better understanding of human voice production process, to make pitch-synchronous segmentation of voice signals, and to make visual representations of pitch marks and timbre spectra with high resolution. The traditional spectrogram segments the voice signals with a process window of fixed size and fixed shift, then performs fast Fourier transformation after multiplied with a window function, typically a Hamming window. Then display power spectrum in both frequency and time. Pitch information and timbre information are mixed. The new design segments the signals into pitch periods, either using the derivatives of the EGG signals or based on the voice signals, then performs Fourier analysis to the segment of signals in each pitch period without using a window function. The pitch information and the timbre information are cleanly separated. The graphical representations of both pitch marks and timbre spectra exhibit high resolution and high accuracy. Detailed analysis of simultaneously acquired voice and EGG signals provides a more precise understanding of human-voice production process. The transient theory of voice production, proposed by Leonhard Euler in early 18th century, is substantiated with modern data. Based on the transient theory of voice production, a pitch-synchronous spectrogram software is developed, which makes a visual representation of pitch marks and timbre spectra. In addition, the timbre spectrum and the power evolution pattern in each pitch period can be displayed individually. Simultaneously acquired voice and EGG signals indicates that each glottal closing triggers a decaying elementary wave in the vocal tract. A superposition of those elementary waves constitutes voice. Based on that concept and using EGG data, a pitch-synchronous voice signal processing method is developed. The voice signal is first segmented into pitch periods, then the two ends are equalized. Fourier analysis is applied to obtain the timbre spectrum of each pitch period. High resolution display of timbre spectrum is generated. The power evolution pattern in each pitch period is also displayed.

Spectrum of mandibular and maxillary pathologies as assessed with dentascan: A pictorial essay

Introduction: Dentascan is a CT imaging software that provides three dimensional display and high resolution panoramic views of the jaw. It has become an important aspect of evaluation of mandibular and maxillary pathologies due to its advantages over two dimensional techniques and conventional CT. Materials and Methods: 60 patients presenting with jaw lesions, were studied using Dentascan software. The aim of the study was to explore the spectrum of findings in various mandibular and maxillary pathologies as well as define their extent and involvement using DentaScan. Results: Impacted mandibular molars constituted 45% of cases followed by tumors and inflammatory lesions (36.6 %). Of the 22 tumors and inflammatory lesions, giant cell granulomas and radicular cysts, accounted for 22.7% each while osteomyelitis constituted 18%. Other lesions included osteosarcoma, buccal space infection, ameloblastoma, adenomatoid odontogenic tumor, dentigerous cysts and carcinoma alveolus. Trauma leading to facial fractures and TMJ pathologies constituted 8.3% and 10% of cases respectively. Conclusion: DentaScan is a valuable tool in evaluation of maxillary and mandibular pathologies including tumors/cysts, inflammatory /infectious lesions, TMJ ankylosis and facial fractures. By providing information superior to radiographs and conventional computed tomography, it plays a valuable role in pre-operative assessment of various pathologies.

Contour generation algorithm for projection mask stereolithography 3D printing process

Projection mask stereolithography is a latest technology in 3D printing industry. It relies on UV projection to cure the photocurable resin layer-by-layer to build the solid 3D object. The projections are generated from tessellated STL CAD model using contour generation algorithm that generates 2D contours as the projection mask. The computational of the algorithm consumes a lot of memory for high-resolution printing. Low-resolution causes the stair-case effect to visibly appear on the printed model. Using real-time contour generation algorithm reduces the memory consumption and retains the high-resolution printing quality and accuracy. Pixel line mapping algorithm is implemented on the generated line segments to scale the line segments with respect to the display resolution of the projection device. Contour loop algorithm connects each of these pixel line segments into multiple closed-loop contours. The algorithms are implemented on an Alien STL model having 150350 facets. It is found that the pixel mapping algorithm correctly scales the model while retaining the aspect ratio of the model. The result of contour loop algorithm shows that the mean contour loop execution time is 0.87 milliseconds which is relevant for real-time application.

Electro-static discharge failure analysis and design optimization of gate-driver on array circuit in InGaZnO thin film transistor backplane

There is a risk of InGaZnO thin film transistor (IGZO TFT) failure, especially electro-static discharge (ESD) damage of gate driver on array (GOA) circuits, due to the combination of Cu interconnect, InGaZnO (IGZO) active layer and SiN&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;/SiO&lt;sub&gt;2&lt;/sub&gt; insulating layer used to realize large-scale ultra-high resolution display. It is found that the IGZO TFT damage position caused by ESD occurs between the source/drain metal layer and the gate insulator. The Cu metal of gate electrode diffuses into the gate insulator of SiN&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;/SiO&lt;sub&gt;2&lt;/sub&gt;. The closer to the ESD damage area the IGZO TFT is, the more serious the negative bias of its threshold voltage (&lt;i&gt;V&lt;/i&gt;&lt;sub&gt;th&lt;/sub&gt;) is until the device is fully turned on. The IGZO TFT with a large channel width-to-length ratio(&lt;i&gt;W&lt;/i&gt;/&lt;i&gt;L&lt;/i&gt;) in GOA circuit results in a serious negative bias of threshold voltage. In this paper, the ESD failure problem of GOA circuit in the IGZO TFT backplane is systematically analyzed by combining the ESD device level analysis with the system level analysis, which combines IGZO TFT device technology, difference in metal density between GOA region and active area on backplane, non-uniform thickness distribution of gate metal layer and gate insulator and so on. In the analysis of ESD device level, we propose that the diffusion of Cu metal from gate electrode into SiN&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;/SiO&lt;sub&gt;2&lt;/sub&gt; leads to the decrease of effective gate insulator layer, and that the built-in space charge effect leads to the decrease of the anti-ESD damage ability of IGZO TFT. In the analysis of ESD system level, we propose that the density of metal layers in GOA region is 4.5 times higher than that in active area of display panel, which makes the flatness of metal layer in GOA region worse. The non-uniformity of thickness of Cu metal film, SiN&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; film and SiO&lt;sub&gt;2&lt;/sub&gt; film around glass substrate lead to the position dependence of the anti-ESD damage ability of IGZO TFT in the GOA region. If there is a transition zone of film thickness change in IGZO TFT with large area, the ESD failure will occur easily. Accordingly, we propose to split large area IGZO TFT into several sub-TFT structures, which can effectively improve the ESD failure.

Low power stretchable active-matrix red, green, blue (RGB) electrochromic device array of poly(3-methylthiophene)/Prussian blue

We report the fabrication of a stretchable array of active-matrix (AM) electrochromic devices (ECDs). The ECD is made of poly(3-methylthiophene) and Prussian blue electrodes with a mixed gel electrolyte of acetonitrile, poly(methyl methacrylate), propylene carbonate, and lithium perchlorate. The ECD displays can express red, green, or blue (RGB) depending on the applied voltage and has a high stability in air. It exhibits low power consumption levels of 331 and 378 μW cm−2 (10 s duration) at −1.0 and 1.0 V, respectively, and a high coloration efficiency of 201.6 cm2 C−1 at 1.0 V. A 4 × 4 AM ECD array is integrated on a deformable Ecoflex substrate via a dry transfer method using patterned liquid metal interconnections. The display shows a mechanical stability under bending and biaxial stretching by 30%. Finite element method analysis of the strain distribution also confirms that strain is not applied to the ECDs, guaranteeing stable operation of the array under deformation. Furthermore, a stretchable 6 × 6 AM ECD array for higher resolution display also exhibits mechanical stability under 30% biaxial stretching. This work demonstrates the high potential of our stretchable ECD array in low power-consuming displays for stretchable electronics, wearable devices, and electronic skin.

Quantitative evaluation method of visual display resolution based on human visual perception

AbstractAs a manner of evaluating visual display resolution, contrast modulation has been widely used for decades. But, as various types of sub‐pixel layout are adopted for flat panel displays, the contrast modulation metric shows a limitation that it is not consistent with human visual perception on those displays. To overcome this limitation, a new quantitative metric is proposed in this paper by introducing structure comparison and combining it with contrast modulation. Experimental results performed on TV displays with various sub‐pixel structures demonstrate that the proposed metric has higher correlation with perceived visual resolution than the conventional metric.

Display in the Wild (DIW): An Adaptive Projection-Imaging System to Screen Geometry in Real Time

TVs and monitors are among the most widely used displays in various environments. However, they have limitations in their physical display conditions, such as a fixed size/position and a rigid/flat space. In this paper, we suggest a new “Display in the Wild” (DIW) concept to overcome the aforementioned problems. Our proposed DIW system allows us to display a flexibly large screen on dynamic non-planar surfaces at an arbitrary display position. To implement our DIW concept practically, we choose a projector as the hardware configuration in order to generate a screen anywhere with different sizes. However, distortion occurs when the projector displays content on a surface that is dynamic and/or non-planar. Therefore, we propose a distortion correction method for DIW to overcome the aforementioned surface constraints. Since projectors are not capture devices, we propose using a depth camera to determine the distortions on the surfaces quickly. We also propose DIW-specific calibration and fast/precise correction methods. Our calibration method is constructed to detect the projection surface easily and quickly, and also allows our proposed system to accommodate the intrinsic parameters such as a display resolution and field of view. We accomplish a fast undistortion process of the projector by considering only surface boundary pixels, which enables our method to run in real time. In our comprehensive experiments, the proposed DIW system generates undistorted screens such as TVs and monitors on dynamic non-planar surfaces at an arbitrary display position with Unmanned Aerial Vehicles (UAVs) in a fast and accurate manner, demonstrating its usefulness in practical DIW scenarios.

Display unit using laser scanning device

AbstractWe are developing a projector system with scanning fiber device and its control system. Our novel scanning systems of scanning fiber device provide high resolution, uniform brightness, and rectangular display area, which are difficult challenges in conventional scanning fiber device.

Performance and usability tradeoff in a cluster display wall

Cluster-based display walls provide cost-effective and scalable display infrastructures with high resolution and large display area, making them suitable for a wide range of high-resolution applications. As a consequence, a wide offer of new cluster display-wall platforms together with their software frameworks have been proposed. Their performance and the satisfaction of their users have aroused the interest of some researchers. This work is focused on the Liquid Galaxy cluster display wall originally built to run Google Earth to create an immersive experience for the users. In this paper, the Liquid Galaxy is benchmarked running Google Earth, as a representative interactive application with high performance requirements, in different configurations and environments, to test the satisfaction, effectiveness and efficiency. Thus, we wish to know how users react to the system performance. In order to do so, we use a performance metric defined in previous research to relate the performance of the system with the user’s perception. Taking into account the trend of this metric in the experimentation, we model the behavior of the system in a way that the performance for any given visualization cluster running Google Earth could be predicted by using a reference system.

Kernel Foveated Rendering

Foveated rendering coupled with eye-tracking has the potential to dramatically accelerate interactive 3D graphics with minimal loss of perceptual detail. In this paper, we parameterize foveated rendering by embedding polynomial kernel functions in the classic log-polar mapping. Our GPU-driven technique uses closed-form, parameterized foveation that mimics the distribution of photoreceptors in the human retina. We present a simple two-pass kernel foveated rendering (KFR) pipeline that maps well onto modern GPUs. In the first pass, we compute the kernel log-polar transformation and render to a reduced-resolution buffer. In the second pass, we carry out the inverse-log-polar transformation with anti-aliasing to map the reduced-resolution rendering to the full-resolution screen. We have carried out pilot and formal user studies to empirically identify the KFR parameters. We observe a 2.8X -- 3.2X speedup in rendering on 4K UHD (2160p) displays with minimal perceptual loss of detail. The relevance of eye-tracking-guided kernel foveated rendering can only increase as the anticipated rise of display resolution makes it ever more difficult to resolve the mutually conflicting goals of interactive rendering and perceptual realism.