High-resolution Display Research Articles

Achromatic doublet electrowetting prism array for beam steering device in foveated display.

A foveated display is a technology that can solve the problem of insufficient angular resolution (relative to the human eye) for near-eye display. In a high-resolution foveated display, a beam steering element is required to track the human gaze. An electrowetting prism array is a transmissive non-mechanical beam steering device, that allows a light and compact optical system to be configured and a large aperture possible. However, the view is obstructed by the sidewall of the prism array. When the size of the cell prism is 7mm, the prism array has an 87% fill-factor. To push the fill-factor to 100%, the cell prisms were magnified using a lens array. Image processing was performed such that the image produced by the lens array was identical to the original. Beam steering by refraction is accompanied by chromatic dispersion, which causes chromatic aberration, making colors appear blurry. The refractive index condition to reduce chromatic dispersion was obtained using the doublet structure of the electrowetting prism. The chromatic dispersion was reduced by 70% on average.

Reproduction of Grasping Sensation by High-resolution Suction Tactile Display for Finger Pads

Reproduction of Grasping Sensation by High-resolution Suction Tactile Display for Finger Pads

Distribution Density-Aware Compensation for High-Resolution Stretchable Display

When a stretchable display is stretched, the area of the exposed substrate between the light-emitting diodes (LEDs) increases, decreasing the image luminance. Currently, this problem is not addressed in existing high-resolution display systems. Although the mean-based method and gamma correction method using general image processing techniques, which are first presented in this paper, can compensate for the decrease in luminance, these methods cannot be adaptively applied for stretchable display systems. Therefore, this paper proposes a novel image compensation method optimized for stretchable displays. The proposed distribution density-aware method (DDAM) compensates for the decrease in luminance particularly for the area involving the newly exposed substrate. The DDAM solves the saturation problem associated with the mean-based method and the problem of inaccurate luminance estimation associated with the gamma correction method. Compared with the mean-based method and the gamma correction method, the peak signal-to-noise ratio of the DDAM is 0.600 dB and 1.977 dB higher, respectively. The structural similarity index measure is also 0.055 and 0.057 higher, respectively. In addition, we develop a novel simulator to evaluate the stretching of high-pixel-per-inch displays, which are being actively researched, and use it to verify the performance of above mentioned luminance reduction compensation methods.

Development of a Multi-Projection System for High-Resolution Directional Volumetric Display

Development of a Multi-Projection System for High-Resolution Directional Volumetric Display

Phase-only color rainbow holographic near-eye display.

Color rainbow holography can realize color holographic 3D display without speckle noise under white light illumination. However, traditional color rainbow holograms used for high-resolution static color 3D display or near-eye color display are amplitude-type, resulting in low diffraction efficiency due to the presence of conjugate light. In this Letter, a phase-only color rainbow holographic near-eye display is demonstrated. The calculation of a phase-only color rainbow hologram is realized by combining a band-limited diffraction and a bi-directional error diffusion algorithm with high-frequency blazed gratings coded to control longitudinal dispersion. When the wavelength of illumination light is deviated from the designated wavelength of the hologram, only a certain wavefront aberration is caused, but there is no conjugate light. The phase-only color rainbow holographic near-eye display of both a 2D color image and a 3D scene are implemented by optical experiments. It has potential applications in head-mounted 3D augmented reality displays without vergence-accommodation conflict.

Optofluidic lenticular lens array for a 2D/3D switchable display.

In this paper, we propose an optofluidic lenticular lens array (OLLA) for a two-dimensional/three-dimensional (2D/3D) switchable display. The OLLA includes a bottom substrate layer with lenticular lens structure, a microfluidic layer with microchannels, and a top substrate layer with inlets as well as outlets. A micro gap is formed between the lenticular lens of the bottom substrate layer and the top substrate layer. When air is in the micro gap, the OLLA behaves as a lenticular lens array, which can realize 3D display. When fluid is filled in the micro gap, because the refractive index of the fluid is the same with the lenticular lens structure, the OLLA equivalents to a transparent flat panel, which can realize a 2D display. Experiments verify that a switchable 2D/3D display prototype based on this OLLA and a smartphone achieves both high-resolution 2D display and high-quality 3D display.

High-Resolution Phase-Only Holographic 3D Display Based on Light Field Images Rendered in the Frequency Domain

Phase-only holograms are more attractive than the amplitude holograms for the higher energy utilization and the possibility to realize on-axis holographic 3D display without conjugate image. In this study, we propose a high-resolution phase-only holographic 3D display using the light field images rendered in the frequency domain. The high-resolution phase-only hologram contains a large number of elemental phase-only holograms (EPHs), and each EPH is calculated from the light field image of the corresponding viewing point in frequency domain through weighted GS (Gerchberg-Saxton) algorithm. Parallel calculation is performed to speed up the calculation in the row direction and the previous EPH is used as the initial phase for the current EPH calculation in order to improve the display quality due to the great similarity between adjacent light field images. Two high-resolution phase-only holograms both with the size of 64 mm×64 mm and the resolution of 200k×200k pixels were calculated and printed by our homemade holographic printer. The full-parallax and high quality 3D displays were verified by optical experiments, which have the potential to be applied in holographic advertising and other fields.

Extremely sensitive mechanochromic photonic crystals with broad tuning range of photonic bandgap and fast responsive speed for high-resolution multicolor display applications

Mechanochromic photonic crystals (MPCs) that can change their colors under pressures are highly desired. However, the poor sensitivity of MPCs (including the limited tuning range of photonic bandgap and responsive speed) and stability restrict their practical applications. Here, extremely sensitive MPCs film with outstanding optical performances was fabricated through the self-assembly of the silica particles into di(ethylene glycol) ethyl ether acrylate (DEGEEA) and fixing the ordered structures by photopolymerization. The strong electrostatic repulsion between the particles was experimentally proved to be the key for the self-assembly of silica particles in nonpolar DEGEEA, ruling out the solvation force as the driving force. Compared with the conventional MPCs, the as-fabricated MPCs exhibit significant improvements in optical performances, including broad tuning range of photonic bandgap (362 nm), high sensitivity (7.55 nm/kPa), fast responsive speed (7.0 nm/ms), long-lasting usability (>2 months), wide working temperature range (−20 to100 ℃) and excellent reversibility (>1000 times) in cycling test. Based on these characteristics, the MPCs can be used for display applications with high-resolution (up to 5.0-µm resolution) and full colors. This work provides new insight for the self-assembly of colloids and will extend the applications of MPCs in sensitive sensors, multicolor displays, and smart windows.

Strain mediated light emission using heterojunctions of all-inorganic mixed-halide perovskite nanocrystals via piezo-phototronic effect

Utilizing the superior luminescence properties and high color purity of inorganic perovskite nanocrystals (NCs), we report the fabrication of color-saturated CsPbBr 3−x I x (x = 0–3)/ZnO heterojunctions based white light emitting diodes (LEDs) on a flexible platform. Here, bandgap engineered mixed halide perovskite NCs have been prepared by solution phase synthesis technique that was spin coated on sputtered ZnO film, acting as an electron injector layer as well as an efficient luminescent material. Broad (~ 350–700 nm) electroluminescence (EL) emission features covering the near UV and entire visible region of the electromagnetic spectrum have been successfully achieved at an ambient (humidity ~ 50–55%) condition with comparatively lower forward bias (V th ~ 2 V). Finally, we demonstrate the significant enhancement (up to ~ 75%) of EL intensity by applying an external stress owing to the piezoelectric properties of ZnO films. The modulation of energy band alignment in CsPbBr 3 /ZnO heterojunction due to the local strain induced positive piezo-potential in ZnO leads to an enhanced radiative recombination efficiency in CsPbBr 3 domain, resulting in superior EL emission characteristics. The combinatorial fascinating optical properties of inorganic perovskites and piezo-phototronic effect of ZnO provide a promising platform to fabricate highly luminescent LEDs that may find perspective applications in high-resolution flexible display devices and wearable electronics. • Band gap engineered mixed halide inorganic perovskite NCs (CsPbBr 3−x I x (x = 0–3)) by solution phase synthesis technique. • Perovskite/ZnO p-n junction based moisture resistant broad white LEDs under fairly lower forward bias of ~ 2V. • Successful tuning of EL emission by increasing the I - /Br - ratio of mixed halide perovskites through anion exchange reaction. • Enhancement of EL intensity up to ~ 75% by applying an external stress owing to the piezoelectric properties of ZnO films.

Fast method for high-resolution holographic 3D display with white light as illumination

In this research, we propose a fast-computational light field image encoding method for a white light high-resolution full-parallax holographic 3D display and full-color rainbow holographic 3D display. With this method, a novel priority-based sequential rendering is used to improve the computation speed. The local visible 3D data is rendered at a higher priority and then used for rendering multiple local element light field images (EIs) at the holographic plane with the corresponding pinhole array behind the holographic plane. The EIs are independently coded as hogels by multiplying the corresponding phase function without using computation-intensive fast Fourier transform. This parallel computation method is implemented for both a full-parallax holographic 3D display and full-color rainbow holographic 3D display. An ultra high-resolution of a full-parallax hologram and a full-color rainbow hologram both at the resolution of 200 000 × 200 000 pixels only cost 14 min and 78 min, respectively. Our experimental results have also shown the effectiveness of the proposed high-resolution 3D display method.

Projection optical engine design based on tri-color LEDs and digital light processing technology.

Digital light processing (DLP) is currently a cutting-edge technology for desktop projection optical engines. Due to the passive luminescence characteristics, the DLP projection engine needs a few specific illumination optical components for light collimation, homogenization, and color combination, together with a projection lens matching the DLP chip and magnifying the image. In this paper, we propose a design approach that first splits the DLP projection optical engine into individual components for separate design, and then integrates them into a whole system for further verification. For the first step, the collimating lens group is designed for light collection, and the dichroic mirrors are used to fold the light path based on tri-color LED light sources. For the second step, a fly-eye lens and the corresponding relay lens group are designed to achieve uniform illumination on the DMD chip. The third step is to optimize the projection lens group for high-resolution projection display. Based on the design and simulation, the optical efficiency is 63.4% and the uniformity reaches 94.9% on the projection screen. The modulation transfer function (MTF) of the projection lens is higher than 0.4 at 66 lines for the distance of 500∼1500mm, and the distortion is lower than 1%. Simulation results show that the total luminous flux is estimated to reach 224.15 lm when the powers of tri-color LEDs are 21 W, 15.5 W, and 25 W, respectively. A projector prototype is built and tested for further verification, which provides a luminous flux of 220.43 lm and uniformity of 90.22%, respectively. The proposed design, demonstrated by both simulation and experiment, exhibits high feasibility and application potential in state-of-the-art commercial projector design.

P‐17.2: Automotive multi‐screen with ambient light sensor

BOE has made a 12.3‐inch automotive multi‐screen module with ambient light sensor. This product integrates the ambient light sensor on the surface of the panel, and the demo can realize 4K high resolution display and can support separate display by screen. At the same time, in order to make the product more beautiful and simple, the ultra narrow splicing design is used.

Design and validation of a handheld capnography device for cardiopulmonary assessment based on the Arduino platform

The design of a handheld capnography device is in great demand because of its effective and practical uses in all cardiac arrest resuscitations, according to the recommendation of the American Heart Association. Herein, a handheld capnography device that can be used in clinical settings and the home environment is reported. The proposed device was developed by using an infrared CO2 sensor, Arduino Mega2560, and a high-resolution display (2.8”). Furthermore, two rechargeable batteries (7.6[Formula: see text]V, 0.99[Formula: see text]A) and a secure digital card with a capacity of 16[Formula: see text]GB were incorporated to increase the portability and usability of the device. Algorithms were implemented to measure standard features, namely, inspired CO2 (ICO2), end-tidal CO2 (EtCO2), and respiratory rate (RR). The features of 15 healthy subjects were recorded by using the developed prototype and the standard capnography device (CapnostreamTM20 Model CS08798). Validation was performed with Bland–Altman plots. Findings revealed that mean differences [Formula: see text] standard deviations for the set limits of ICO2, EtCO2 and RR were 0.29 ± 1.30 millimeters of mercury (mmHg), 0.15 ± 1.77 mmHg and 0.40 ± 0.97 breaths per minute (bpm), respectively. Most of the differences among device measurements across all features fell within the 95% limits of agreement. Thus, the developed device may help manage respiratory distress conditions in and outside of a hospital setting.

Completely merged multi-color asymmetric pyramid with suppressed stress and defect density

The selective area growth (SAG) technique enables the creation of multi-color micro-structures. However, the substrate pattern to obtain multi-color and mass transfer of these micro-structures are complicated to achieve. Moreover, high dislocation density as well as large residual stress in c-plane quantum wells still remain challenges. Here, an improved SAG strategy was proposed to achieve completely merged asymmetric pyramids on closely connected deep-concave holes via the lateral overgrowth of adjacent pyramids. These asymmetric pyramids were directly grown on the sapphire substrate, making mass transfer be possible. Growth rate distinction appears at the different positions of the overgrowth region, resulting in a multi-wavelength emission. More importantly, the residual stress and the dislocation density can be suppressed by utilizing the deep-hole pattern and lateral overgrowth, contributing to a lower piezoelectric polarization field and a higher spontaneous emission rate. These ultrafast and high-efficient multi-color micro-LEDs are suitable for the application in high-resolution display, flexible devices, and high-speed visible-light-communication.

Journal of the Society for Information Display

Jiun-Haw Lee Editor in Chief In the May issue, JSID will publish a special issue of (part of) “Expanded Distinguished Papers of Display Week 2021.“ Those papers were nominated by the Program Committee of SID Display Week and passed the expedited review, which was somewhat stricter than normal because of time constraints. Those papers will remain open access until the end of 2021. When inviting the authors of the SID-sponsored conference to expand their results to a full paper and submit to JSID, sometimes they ask: “May I use the same context (or figures) of the SID-sponsored conference proceeding in the expanded paper?” In the Editorial published in April, we clarified this issue of novelty and plagiarism from different viewpoints: legally speaking, the author, and the journal. Take “Expanded Distinguished Papers of Display Week“ as an example. These abstracts are nominated by the Program Committee of SID Display Week with a quick review and limited content (within 4 pages). Although the results are interesting, the abstracts sometimes cannot contain all the information that is required for a full paper (typically >6 pages) published in JSID. When preparing the manuscript of JSID, the authors are allowed to use part of or all of the content in the abstracts submitted to SID Display Week by the same authors. However, it cannot apply to the case for expanding the conference papers sponsored by other societies. Evaluation and formulation of the sense of social telepresence in video-mediated communication systems: Contribution of eye contact to enhancing social telepresence | Shinji Kimura, et al. | DOI: 10.1002/jsid.976 There is a strong demand for online meetings, especially after the COVID-19 pandemic. Compared to face-to-face communication, the user experience for existing video-mediated communication (VMC) is still not satisfactory, unfortunately, even though we can use high-resolution display, together with high-speed internet. To create the “real” feeling of face-to-face communications, especially in one-on-one situations, the authors pointed out two important human factors: “eye contact” and “life-size image.” A prototype of the VMC system was demonstrated with a large-sized transparent organic light-emitting diode (OLED) display and a camera behind the scenes. Using a large display to achieve a life-sized image is straightforward. A camera behind the transparent display was employed to align the eye gaze with the image and create the feeling of “eye contact.” Early defect identification for micro light-emitting diode displays via photoluminescent and cathodoluminescent imaging | Keith Behrman, et al. | DOI: 10.1002/jsid.985 Micro light-emitting diodes (μ-LEDs) are an emerging display technology that has attracted lots of attention for different applications, such as augmented reality, small-sized displays (∼2 inches), and huge displays (more than 100 inches). In such a display, each LED is driven independently for electroluminescence (EL) emission. However, it is not easy to achieve high process yield for the millions of pixels in one display. Hence, online detection is required during manufacture. In this paper, the authors compare two different measurement methods, photoluminescence (PL) and cathodoluminescence (CL), with EL results. It was found that PL is not a satisfactory tool to reveal the defects. On the other hand, CL images can be accurate, up to ∼70%, when mapping to an EL image. Different defect modes during the process flow were also analyzed. JSID is published monthly by Wiley. Subscription fees apply, but SID members and student members have free online access via sid.org/Publications.aspx. Many universities also have an institutional subscription. JSID is indexed in the Web of Science. Submit your original manuscript online via mc.manuscriptcentral.com/sid. Author guidelines can be found on the Journal's homepage: tinyurl.com/jsidhome. Editorial board: tinyurl.com/jsideb. Please direct any questions about JSID to its editor in chief at editor@sid.org. EarlyView: accepted papers about to be published can be accessed online via tinyurl.com/jsidev. The Journal is soliciting review papers on any display-related topic. If you have a great idea for a review paper, please contact the editor at editor@sid.org. Page charges for invited review papers will be waived.

Amorphous NdIZO Thin Film Transistors with Contact-Resistance-Adjustable Cu S/D Electrodes

High-performance amorphous oxide semiconductor thin film transistors (AOS-TFT) with copper (Cu) electrodes are of great significance for next-generation large-size, high-refresh rate and high-resolution panel display technology. In this work, using rare earth dopant, neodymium-doped indium-zinc-oxide (NdIZO) film was optimized as the active layer of TFT with Cu source and drain (S/D) electrodes. Under the guidance of the Taguchi orthogonal design method from Minitab software, the semiconductor characteristics were evaluated by microwave photoconductivity decay (μ-PCD) measurement. The results show that moderate oxygen concentration (~5%), low sputtering pressure (≤5 mTorr) and annealing temperature (≤300 °C) are conducive to reducing the shallow localized states of NdIZO film. The optimized annealing temperature of this device configuration is as low as 250 °C, and the contact resistance (RC) is modulated by gate voltage (VG) instead of a constant value when annealed at 300 °C. It is believed that the adjustable RC with VG is the key to keeping both high mobility and compensation of the threshold voltage (Vth). The optimal device performance was obtained at 250 °C with an Ion/Ioff ratio of 2.89 × 107, a saturation mobility (μsat) of 24.48 cm2/(V·s) and Vth of 2.32 V.

Investigations of Sidewall Passivation Technology on the Optical Performance for Smaller Size GaN-Based Micro-LEDs

Micro-light emitting diodes (Micro-LEDs) based on III-nitride semiconductors have become a research hotspot in the field of high-resolution display due to its unique advantages. However, the edge effect caused by inductively coupled plasma (ICP) dry etching in Micro-LEDs become significant with respect to the decreased chip size, resulting in a great reduction in device performance. In this article, sector-shaped GaN-based blue Micro-LEDs are designed and fabricated. Additionally, the device performance of different size Micro-LEDs with passivation are investigated with respect to those without passivation. Several methods have been applied to minimize the etching damage near the edge, including acid-base wet etching and SiO2 passivation layer growth. The room temperature photoluminescence (PL) results demonstrate that the light emission intensity of Micro-LEDs can be significantly enhanced by optimized passivation process. PL mapping images show that the overall luminescence of properly passivated Micro-LEDs is enhanced, the uniformity is improved, and the effective luminescence area is increased. The recombination lifetime of carriers in Micro-LEDs are increased by the usage of passivation process, which proves the reduction in non-radiative recombination centers in Micro-LEDs and improved luminescence efficiency. As a result, the internal quantum efficiency (IQE) is improved from 14.9% to 37.6% for 10 μm Micro-LEDs, and from 18.3% to 26.9% for 5 μm Micro-LEDs.

Circuit-on-Display: A Flexible, Invisible Hybrid Electromagnetic Sensor Concept

There have been scarce interactions between microwave circuits and display technologies over the past few decades. However, the two share many similarities leaving room for integration and co-development. Hence, we present a Circuit-on-Display (CoD) concept that dually functions as a radio-frequency transceiver and a high-resolution touch screen display. The approach is realized through a flexible, invisible hybrid electromagnetic sensor (HEMS) which is situated inside a high-resolution display panel. The CoD is integrated within a real-life millimeter-wave 5G NR Android-based cellular handset prototype to demonstrate a foreside beamforming coverage and a touch operation with high-resolution and optimal image quality. The devised HEMS prototype independently features flexibility, optically invisibility (transmittance >88%), and multi-functionality (system gain of 20.72 dB, beam scanning range of ±40°, and mutual capacitance change ratio >4.42%). The devised approach provides a new class of approach to enable microwave integrated circuits for new generation wireless electronics.

Ligand-Assisted Direct Photolithography of Perovskite Nanocrystals Encapsulated with Multifunctional Polymer Ligands for Stable, Full-Colored, High-Resolution Displays.

Micropatterns with a high stability, definition, and resolution are an absolute requirement in advanced display technology. Herein, patternable perovskite nanocrystals (PNCs) with excellent stability were prepared by exchanging pristine ligands with multifunctional polymer ligands, poly(2-cinnamoyloxyethyl methacrylate). The polymer backbone contains a cinnamoyl group that has been widely employed as a photo-cross-linker under 365 nm UV irradiation. Also, the terminal group is readily adjustable among NH3Cl, NH3Br, and NH3I, allowing us to obtain multicolored PNCs via instant anion exchange. Furthermore, the resulting ligand exchanged PNCs exhibited enhanced stability toward polar solvents without any undesirable influence on the structural or optical properties of the PNCs. Using anion exchanged PNCs, RGB microarrays with a subpixel size of 10 μm × 40 μm were successfully demonstrated. Our results highlight the versatility and feasibility of a simplified patterning strategy for nanomaterials, which can be generally applied in the fabrication of various optoelectronic devices.

Foveated Encoding for Large High-Resolution Displays

Collaborative exploration of scientific data sets across large high-resolution displays requires both high visual detail as well as low-latency transfer of image data (oftentimes inducing the need to trade one for the other). In this work, we present a system that dynamically adapts the encoding quality in such systems in a way that reduces the required bandwidth without impacting the details perceived by one or more observers. Humans perceive sharp, colourful details, in the small foveal region around the centre of the field of view, while information in the periphery is perceived blurred and colourless. We account for this by tracking the gaze of observers, and respectively adapting the quality parameter of each macroblock used by the H.264 encoder, considering the so-called visual acuity fall-off. This allows to substantially reduce the required bandwidth with barely noticeable changes in visual quality, which is crucial for collaborative analysis across display walls at different locations. We demonstrate the reduced overall required bandwidth and the high quality inside the foveated regions using particle rendering and parallel coordinates.