Multi‐primary design of spectrally accurate displays

Abstract— Spectral color reproduction overcomes some inherent problems of colorimetric reproduction. An implementation of a spectral display for surface color reproduction, capable of reproducing a desired spectrum for each pixel, based on multi‐primary projection technology, is presented. A light source with a spectrum identical to that of the illumination is filtered by a positive linear combination of several color filters, which reproduces the reflectance spectra. The spectra of the color filters are tailored to span the space of possible surface spectra. Various methods for choosing the color filters vis‐à‐vis the required performance are discussed in detail. Soft‐proofing application is examined as a test case for the concept.     

Review Paper: Multi‐primary‐color displays: The latest technologies and their benefits

Abstract— Multi‐primary‐color (MPC) display technology is one of the fastest emerging research areas in recent years. Wide‐color‐gamut display devices have been required for visually sufficient and/or accurate color reproduction. It is well known that MPC displays can reproduce accurate colors with high efficiency. In addition, not only the image‐quality improvement but some other performance of display devices is also required for display devices. This paper reviews achievements in MPC display technologies and focuses on the benefits of MPC displays: power‐savings and high resolution.     

Multi‐Tracking of First Order Multi‐Agent Networks Via Self‐Triggered Control

A multi‐tracking problem of multi‐agent networks is investigated in this paper where multi‐tracking refers to that the states of multiple agents in each subnetwork asymptotically converge to the same desired trajectory in the presence of information exchanges among subnetworks. The multi‐tracking of first order multi‐agent networks with directed topologies was studied. Self‐triggered protocols were proposed along with triggering functions to solve the stationary multi‐tracking and bounded dynamic multi‐tracking. The self‐triggered scheduling is obtained, and the system does not exhibit Zeno behavior. Numerical examples are provided to illustrate the effectiveness of the obtained criteria.     

Image formation modeling and analysis of near‐eye light field displays

Near‐eye light field displays based on integral imaging through a microlens array provide attractive features like ultra‐compact volume and freedom of the vergence‐accommodation conflict to head‐mounted displays with virtual or augmented reality functions. To enable optimal design and analysis of such systems, it is desirable to have a physical model that incorporates all factors that affect the image formation, including diffraction, aberration, defocusing, and pixel size. Therefore, in this study, using the fundamental Huygens‐Fresnel principle and the Arizona eye model with adjustable accommodation, we develop an image formation model that can numerically calculate the retinal light field image with near‐perfect accuracy, and experimentally verify it with a prototype system. Next, based on this model, the visual resolution is analyzed for different field of views (FOVs). As a result, a rapid resolution decay with respect to FOV caused by off‐axis aberration is demonstrated. Finally, resolution variations as a function of image depth are analyzed based on systems with different central depth planes. Significantly, the resolution decay is revealed to plateau when the image depth is large enough, which is different from real‐image type light field displays.     

Color displays and flexible displays using quick‐response liquid‐powder technology for electronic paper

Abstract— Color displays and flexible displays that use electronic liquid powder have been developed. Novel types of color displays using either a colored powder or a color filter are discussed. We have also developed a flexible display with low‐cost substrate films with a high‐throughput roll‐to‐roll manufacturing method. These technologies enable a QR‐LPD to be widely used as an electronic‐paper display.     

True 3‐D scanned voxel displays using single or multiple light sources

Abstract— Conventional stereoscopic displays require viewers to unnaturally keep eye accommodation fixed at one focal distance while they dynamically change vergence to view objects at different distances. This forced decoupling of reflexively linked processes fatigues eyes, causes discomfort, compromises image quality, and may lead to pathologies in developing visual systems. Volumetric displays can overcome this conflict, but only for small objects placed within a limited range of viewing distances and accommodation levels, and cannot render occlusion cues correctly. Our multi‐planar True 3‐D displays generate accommodation cues that match vergence and stereoscopic retinal disparity demands and can display images and objects at viewing distances throughout the full range of human accommodation (from 6.25 cm to infinity), better mimicking natural vision and minimizing eye fatigue.     

Projection‐based head‐tracking 3‐D displays

Abstract— This paper describes the construction and operation of four 3‐D displays in which each display produces two images for each eye and thus fits into the category of projection‐based binocular stereoscopic displays. The four 3‐D displays described are pico‐projector‐based, liquid‐ crystal—on—silicon (LCOS) conventional projector‐based, 120‐Hz digital‐light‐processor (DLP) projector‐ based, and the HELIUM3D system. In the first three displays, images are produced on a direct‐view LCD whose conventional backlight is replaced with a projection illumination source that is controlled by a multi‐user head tracker; novel steering optics direct the projector output to regions referred to as exit pupils located at the viewers' eyes. In the HELIUM3D display, the image information is supplied by a horizontally scanned, fast, light valve whose output is controlled by a spatial light modulator (SLM) to direct images to the appropriate viewers' eyes. The current statu s and the multimodal potential of the HELIUM3D display are described.     

Transmissive electrowetting‐based displays for portable multimedia devices

Abstract— Electrowetting‐based displays have been successfully demonstrated in reflective mode, showing video capability and high optical performance. However, because this technology is based on a high‐efficiency optical switch operating between a light‐absorbing state and a light‐transmitting state, the technology lends itself naturally to a transmissive mode enabling a complete range of applications. This paper describes the first active‐matrix full‐color transmissive electrowetting displays including its main technical and system aspects. Two architectures have been demonstrated: one uses color filters, the other field‐sequential‐color illumination. The paper also introduces alternative concepts for more efficient color transmissive electrowetting displays with multiple absorbing layers.     

Flexible electronic‐paper active‐matrix displays

Abstract— A100‐μm‐thick 320 × 240‐pixel active‐matrix display integrated into a functional‐device prototype is presented. The active matrix is composed of alternating layers of organic materials and gold. A six‐mask photolithographic process is used. An electrophoretic electronic imaging film is laminated on top of the active matrix. The display is bendable to a radius of 7.5 mm for more than 30,000 repetitions.     

Drivers for free‐form modular displays

Abstract— When displays of different sizes and shapes are required, a modular display system seems to be a good solution. Many systems offer only a limited freedom of shapes. The display can be scaled, but no irregular shapes can be created. If those shapes can be created, the configuration is often manual. A more intelligent modular system allows all shapes to be created and configures automatically. This paper presents two drivers that can be used in such a modular system. The first driver ensures that the data finds its way to every module and is displayed, even if there are some “holes” in the display due to missing modules. The second driver adds some extra functionality. The precise display configuration can be detected, and in the graphical user interface (used for controlling the display) the user sees an updated view of the display configuration when modules are added or removed. Both drivers have been proven successful and results are presented in this paper.     

Novel application of ink‐jet‐printing technology in multi‐domain alignment liquid‐crystal displays

Abstract— Based on the drop‐on‐demand characteristics of ink‐jet printing, the multi‐domain alignment liquid‐crystal display (LCD) could be achieved by using patterned polyimide materials. These polyimide ink locations with different alignment procedures could be defined in a single pixel, depending on the designer 's setting. In this paper, we combined the electro‐optical design, polyimide ink formulation, and ink‐jetting technology to demonstrate the application of multi‐domain alignment liquid‐crystal display manufactory. The first one was a multi‐domain vertical‐alignment LCD. After the horizontal alignment material pattern on the vertical alignment film, the viewing angle would reach 150° without compensation film. The second one was a single‐cell‐gap transflective LCD within integrating the horizontal alignment in the transmissive region and hybrid alignment in the reflective one in the same pixel. In addition, this transflective LCD was also demonstrated in the form of a 2.4‐in. 170‐ppi prototype.     

A new current‐mirror pixel circuit employing poly‐Si TFTs for active‐matrix organic light‐emitting‐diode displays

Abstract— A novel active‐matrix organic light‐emitting‐diode (AMOLED) display employing a new current‐mirror pixel circuit, which requires four‐poly‐Si TFTs and one‐capacitor and no additional signal lines, has been proposed and sucessfully fabricated. The experimental results show that a new current mirror can considerably compensate luminance non‐uniformity and scale down a data current more than a conventional current‐mirror circuit in order to reduce the pixel charging time and increase the minimum data current. Compared with a conventional two‐TFT pixel, the luminance non‐uniformity induced by the grain boundaries of poly‐Si TFTs can be decreased considerably from 41% to 9.1%.     

Multi‐view 3‐D display employing a flat‐panel display with slanted pixel arrangement

Abstract— A flat‐panel display with a slanted subpixel arrangement has been developed for a multi‐view three‐dimensional (3‐D) display. A set of 3M × N subpixels (M × N subpixels for each R, G, and B color) corresponds to one of the cylindrical lenses, which constitutes a lenticular lens, to construct each 3‐D pixel of a multi‐view display that offers M × N views. Subpixels of the same color in each 3‐D pixel have different horizontal positions, and the R, G, and B subpixels are repeated in the horizontal direction. In addition, the ray‐emitting areas of the subpixels within a 3‐D pixel are continuous in the horizontal direction for each color. One of the vertical edges of each subpixel has the same horizontal position as the opposite vertical edge of another subpixel of the same color. Cross‐talk among viewing zones is theoretically zero. This structure is suitable for providing a large number of views. A liquid‐crystal panel having this slanted subpixel arrangement was fabricated to construct a mobile 3‐D display with 16 views and a 3‐D resolution of 256 × 192. A 3‐D pixel is comprised of 12 × 4 subpixels (M = 4 and N = 4). The screen size was 2.57 in.     

Inorganic light‐emitting diode displays using micro‐transfer printing

Large quantities of microscopic red, green, and blue light‐emitting diodes (LEDs) made of crystalline inorganic semiconductor materials micro‐transfer printed in large quantities onto rigid or flexible substrates form monochrome and color displays having a wide range of sizes and interesting properties. Transfer‐printed micro‐LED displays promise excellent environmental robustness, brightness, spatial resolution, and efficiency. Passive‐matrix and active‐matrix inorganic LED displays were constructed, operated, and their attributes measured. Tests demonstrate that inorganic micro‐LED displays have outstanding color, viewing angle, and transparency. Yield improvement techniques include redundancy, physical repair, and electronic correction. Micro‐transfer printing enables revolutionary manufacturing strategies in which microscale LEDs are first assembled into miniaturized micro‐system “light engines,” and then micro‐transfer printed and interconnected directly to metallized large‐format panels. This paper reviews micro‐transfer printing technology for micro‐LED displays.     

Flexible electronic‐paper active‐matrix displays

Abstract— A QVGA active‐matrix backplane was produced on a 25‐μm thin plastic substrate. A four‐mask photolithographic process was used. The insulator layer and the semiconductor layer were organic material processed from solution. This backplane was a combination of the electrophoretic display effects supplied by SiPix and E‐Ink Corp., resulting in electronic‐paper displays with a thickness of 150 and 100 μm, respectively; this is the world's thinnest active‐matrix display ever made.     

High‐contrast front‐projection system for large‐screen displays suppressing reflection and diffusion of ambient light

Abstract— A new front‐projection system for large screens by diffusing only projected light to wards the viewing‐angle range and reflecting ambient light towards the other angle ranges is proposed. With this system, a high‐quality and large‐sized front‐projection display with a high contrast ratio even in a bright room has been realized.     

Multi‐organization scheduling approximation algorithms

In this paper we consider the problem of scheduling on computing platforms composed of several independent organizations, known as the Multi‐Organization Scheduling Problem (MOSP). Each organization provides both resources and jobs and follows its own objectives. We are interested in the best way to minimize the makespan on the entire platform when the organizations behave in a selfish way. We study the complexity of the MOSP problem with two different local objectives—makespan and average completion time—and show that MOSP is strongly NP‐Hard in both cases. We formally define a selfishness notion, by means of restrictions on the schedules. We prove that selfish behavior imposes a lower bound of 2 on the approximation ratio for the global makespan. We present various approximation algorithms of ratio 2 which validate selfishness restrictions. These algorithms are experimentally evaluated through simulation, exhibiting good average performances and presenting good fairness to organizations' local objectives. Copyright © 2011 John Wiley & Sons, Ltd.     

Wrap‐around electrodes for microLED tiled displays

The authors have developed a process to create wrap‐around electrodes (WAEs) on glass for use in tiled microLED display applications. The electrodes have small size and spacing, low resistance, and good reliability. In addition, an opaque overcoat protects the edges of the tiles and reduces seam visibility. These electrodes allow bezel‐free tiled operation for high‐resolution displays.     

Leader‐Following Consensus of Multi‐Agent System with Diffusion

This paper is concerned with the leader‐following consensus problem for multi‐agent systems consisting of one stationary leader and multiple cooperative followers, where the controlling effect of each follower depends on its own state. It is noted that the influence of diffusion among followers is taken into account and the system is modeled by reaction‐diffusion equations. With the assumption of the followers' initial states, a linear control protocol is designed. Based on algebraic graph theory, the method of energy estimates, and Sobolev embedding theorem, the sufficient conditions guaranteeing the leader‐following consensus under the proposed control protocol are provided. Numerical examples illustrate the effectiveness of the theoretical results.     

Performance of liquid‐crystal displays for fire‐service thermal‐imaging cameras

Abstract— As use of handheld thermal‐imaging cameras (TICs) becomes more prevalent in the first‐responder community, it is important that standard test metrics be available to characterize imaging performance. A key performance consideration is the quality of the image presented on the TIC display. This paper focuses on TICs that use liquid‐crystal displays to render an image for the user. Current research on TIC performance for first‐responder applications makes use of trained observers and/or composite‐video‐output‐signal measurements. Trained observer tests are subjective and composite video output tests do not evaluate the performance of the complete imaging system. A non‐destructive objective method was developed that tests the performance of the entire thermal‐imaging system, from the infrared sensor to the display. A thermal target was used to correlate the measured thermal imager composite video output signal with the luminance of the display. A well‐characterized charge‐coupled‐device (CCD) camera and digital recording device were used to measure the display luminance. An electro‐optical transfer function was determined that directly relates the composite video output signal to the luminance of the display, providing a realistic characterization of system performance.