Light Display Research Articles

High brightness and broad modulation bandwidth InGaN-based red micro-LEDs integrated with plasmonic gratings.

We propose red micro-LEDs integrated with plasmonic gratings, which demonstrate high efficiency and broad modulation bandwidth. The Purcell factor and external quantum efficiency (EQE) for an individual device can be improved up to 5.1 and 11%, respectively, due to the strong coupling between surface plasmons and multiple quantum wells. The cross talk effect between adjacent micro-LEDs can be efficiently alleviated as well, thanks to the high-divergence far-field emission pattern. Moreover, the 3-dB modulation bandwidth of the designed red micro-LEDs is predicted to be ∼ 528 MHz. Our results can be used to design high-efficiency and high-speed micro-LEDs for the applications of advanced light display and visible light communication.

P‐8.1: High‐performance AlGaInP Based Red Micro‐LED†

AlGaInP‐based red light‐emitting diode (LED) arrays are a promising technology. However, due to the difficulty of mesa etching, the small size of red Micro‐LEDs is easily affected by edge effects, resulting in low light output power and difficult to meet the requirements of lighting display. We introduce the fabrication method of flip‐chip red Micro‐LED and exhibit the fabrication of devices with good electrical properties and stable optical properties.

P‐7.10: Display illumination with tailored viewing volume

Display technology has been developing rapidly in recent decades and the basic principle is related to the way that the image is illuminated and light is emanated. This work proposes and demonstrates a novel display illuminating scheme which is capable of providing display viewing only in certain spatial regions. For a viewer close and away from the designated regions, the display content becomes invisible. The scheme is associated with an axicon lens [1] and four lenses that enables to view only in designated continuous region, as shown in the Fig. 1. The longitudinal depth‐designed display illumination with the advantages of no lighting‐noise will have impact on intelligent lighting display in the future.

Fabrication technology for light field reconstruction in glasses-free 3D display

ABSTRACT Light field 3D display has attracted great attention as the hardware interface for a virtual 3D application. The design and fabrication of light-modulating structures directly affect the authenticity of the reconstructed 3D image. The critical challenges in 3D display, such as visual fatigue, limited motion parallax, and insufficient light efficiency, are closely related to the inaccurate phase or angular reconstruction of the virtual light field. While the designs of light field modulators are widely introduced in all kinds of studies, the importance of fabrication for 3D display is usually under-estimated. Large format, small feature size, and high precision in shape are the three critical requirements of fabrication for 3D display. In this paper, we focus on the fabrication technologies for light-modulating structures. Fabrication tools for both microstructures and nanostructures are introduced. The fabrication capability, critical challenges and its applications in light field 3D display are discussed. Finally, the future development of 3D display related fabrication technologies are highlighted.

Perceiving fingerspelling via point-light displays: The stimulus and the perceiver both matter.

Signed languages such as American Sign Language (ASL) rely on visuospatial information that combines hand and bodily movements, facial expressions, and fingerspelling. Signers communicate in a wide array of sub-optimal environments, such as in dim lighting or from a distance. While fingerspelling is a common and essential part of signed languages, the perception of fingerspelling in difficult visual environments is not well understood. The movement and spatial patterns of ASL are well-suited to representation by dynamic Point Light Display (PLD) stimuli in which human movement is shown as an array of moving dots affixed to joints on the body. We created PLD videos of fingerspelled location names. The location names were either Real (e.g., KUWAIT) or Pseudo-names (e.g., CLARTAND), and the PLDs showed either a High or a Low number of markers. In an online study, Deaf and Hearing ASL users (total N = 283) watched 27 PLD stimulus videos that varied by Word Type and Number of Markers. Participants watched the videos and typed the names they saw, along with how confident they were in their response. We predicted that when signers see ASL fingerspelling PLDs, language experience in ASL will be positively correlated with accuracy and self-rated confidence scores. We also predicted that Real location names would be understood better than Pseudo names. Our findings supported those predictions. We also discovered a significant interaction between Age and Word Type, which suggests that as people age, they use outside world knowledge to inform their fingerspelling success. Finally, we examined the accuracy and confidence in fingerspelling perception in early ASL users. Studying the relationship between language experience with PLD fingerspelling perception allows us to explore how hearing status, ASL fluency levels, and age of language acquisition affect the core abilities of understanding fingerspelling.

A critical review and future prospects of Dy3+-doped glasses for white light emission applications

Rare-earth (RE)-doped glassy systems gained much interest because of its wide variety of applications in numerous potential fields that include optical fibers, solid state lasers, optical amplifiers, optical thermometry sensors, waveguides, infrared detectors, spectral converters, display devices, and so on. Within RE ions, the trivalent dysprosium (Dy3+) ion is the most unique and characteristic ion to examine emission properties for white light and visible display emitting devices. Because, Dy3+ ion emits two intense emissions in the blue (~480 nm) and yellow (~575 nm) regions that are assigned to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transition energies, respectively. Under the excitation of blue laser, Dy3+ ions exhibit attractive yellowish white fluorescence emission with higher quantum efficiency. In view of the importance of identifying efficient luminescent emitting materials for the development of optical devices, the present work is to investigate white light emission in new glass composition of B2O3 +TeO2 +SrCO3 +ZnO+ZnF2 +Dy2O3 glass and in turn to compare and discuss these results with reported Dy3+:glasses. The tabulated reported data bank for 68 Dy3+:glasses at one place should prove valuable information for future work on rationalization of theoretical and practical point of view to enrich white light emission quantification, simulation and systemization.

Aberration Compensated Point Light Source Display With High-Resolution

A high-resolution enhanced point light source integral imaging display is proposed. Using additional light sources to create extra point light sources in the point light source plane, the point light sources appeared on the plane that deviated from the expected values because of aberrations in the lens. Previously, only the lens array aberration was corrected and the distance along the horizontal and vertical axes was corrected too. The objective of this paper is to simultaneously correct the aberration between the lens array and the collimating lens, plus the horizontal and vertical axes, and correct the error along the z-axis. So, we determined the distance between the central light source and the additional light source to compensate for lens aberrations. From the experimental results, our technique precisely increased the resolution 3 times in both vertical and horizontal dimensions when compared to a traditional point light source display. Our method is applicable to 3D displays and compensates for the lens array and collimating lens aberrations.

Recent Progress in AC-Driven Organic and Perovskite Electroluminescent Devices

AC-driven EL devices have always been the focus of attention because of their great value in the field of intelligent lighting and multifunctional display. AC-driven EL devices based on various materials and optimization methods have been continuously developed. However, the important luminescent semiconductor materials have rarely been systematically studied. Herein, the development of efficient and stable organic and perovskite EL devices, including the optimization of light-emitting materials, and the device structures are comprehensively studied. The different frequency-dependent characteristics of AC-driven EL devices based on organic semiconductors and perovskite semiconductors are mainly introduced due to the discrepancy in the characteristics of the materials themselves. In addition, approaches to reduce the driving voltage and enhance the luminescence performance of AC-driven organic EL devices are also presented. For AC-driven perovskite EL devices, the bias voltage with frequent switching of the electric field direction can alleviate the thermal degradation and charge accumulation of the material to improve the stability of the devices and also effectively suppress the phenomenon of ion migration. The unique advantages of the AC driving mode in the realization of color tunable EL devices are revealed. The application potential and challenges of AC-driven EL devices are discussed.

Preview the Products on Display at Display Week 2022

Preview the Products on Display at Display Week 2022

How users of automated vehicles benefit from predictive ambient light displays

With the introduction of Level 3 and 4 automated driving, the engagement in a variety of non-driving related activities (NDRAs) will become legal. Previous research has shown that users desire information about the remaining time in automated driving mode and system status information to plan and terminate their activity engagement. In past studies, however, the positive effect of this additional information was realized when it was integrated in or displayed close by the NDRA. As future activities and corresponding items will be diverse, a device-independent and non-interruptive way of communication is required to continuously keep the user informed, thus avoiding negative effects on driver comfort and safety. With a set of two driving simulator studies, we have investigated the effectiveness of ambient light display (ALD) concepts communicating remaining time and system status when engaged in visually distracting NDRAs. In the first study with 21 participants, a traffic light color-coded ALD concept (LED stripe positioned at the bottom of the windshield) was compared to a baseline concept in two subsequent drives. Subjects were asked to rate usability, workload, trust, and their use of travel time after each drive. Furthermore, gaze data and NDRA disengagement timing was analyzed. The ALD with three discrete time steps led to improved usability ratings and lower workload levels compared to the baseline interface without any ALD. No significant effects on trust, attention ratio, travel time evaluation, and NDRA continuation were found, but a vast majority favored the ALD. Due to this positive evaluation, the traffic light ALD concept was subsequently improved and compared to an elapsing concept in a subsequent study with 32 participants. In addition to the first study, the focus was on the intuitiveness of the developed concepts. In a similar setting, results revealed no significant differences between the ALD concepts in subjective ratings (workload, usability, trust, travel time ratings), but advantages of the traffic light concept can be found in terms of its intuitiveness and the level of support experienced.

Highly Luminescent and Ultra‐Stable Perovskite Films with Excellent Self‐Healing Ability for Flexible Lighting and Wide Color Gamut Displays

AbstractMetal halide perovskite quantum dots (QDs) and polymer composite films have witnessed extensive investigation in flexible optoelectronic devices, while the unsatisfactory environmental and mechanical properties of the composite films set substantial limitations for practical applications. Herein, highly luminescent perovskite QDs‐polymer composite films (QPFs) are fabricated with remarkable environmental and mechanical stabilities by incorporation of perovskite QDs into fluoroelastomer polymeric matrix. The stretchable QPFs show excellent self‐healing ability with micron‐ and centimeter‐scale cracks healed in dozens of minutes and hours, respectively, due to the strong dipole–dipole interaction between the CF bonds of fluoroelastomer. After careful optimization of QDs ratios, a flat and smooth film morphology is achieved with a uniform distribution of QDs, which promotes good optical properties with a long PL lifetime of 1213.75 ns and high photoluminescence quantum yields up to 96.1%, and super environmental and mechanical stability These merits of QPFs enable their practical applications in flexible white light‐emitting devices and wide color gamut displays with 124% of standard National Television Standards Committee and 96% of Recommendation 2020, respectively, exhibiting vivid pictures with high saturations for the object colors, indicating great potential toward practical applications.

A STUDY OF LIGHT HIERARCHY IMPACTS IN MOSQUES: A CASE STUDY OF MASJID WAZIR KHAN, LAHORE

Light has always been an icon of magnificent and mystical interplay with architectural spaces. Our built monopoly utilizes natural Light in such a manner that specifies meaningful experience to the spatial design. Light is a supreme element in Islamic architecture that symbolizes supremacy and knowledge, forcing humans to relate to spiritual experience just by being in sacred spaces. The built environment, however, should indicate this worldly Light as depicting paradise, a believable phenomenon even mentioned in our religious manuscripts. Usually, the focus was on the design elements of spatial planning of these built structures, yet other modifying design elements are used better to attain ecstasy and Light is one of them. Almost every religious building in the world has some wonders and depiction that makes them beautiful and recognizable across the globe. Hence Pakistan also has many beautiful buildings with glorious Islamic backgrounds focusing on Light. The Mosque, a perfect symbol of Islamic architecture, has a beautiful play of Light inside that reminds of the holy verses. This study focuses on the play of lights used in mosques as the best manifestation of Islamic architecture based on investigations through descriptive and explorative data for analyses. The study was carried out through a case study of the Wazir Khan Mosque, which is beautifully articulated with hierarchical lighting used to enhance Light's impacts for exploring the lighted spaces. The research findings are that the light display in the various parts of the mosques is beautifully intricated in such a manner as not only those parts keep the Mosque well lit for the Devoutes like the central courtyard, Inner chamber that uses Light in a way that the identification of a place that leaves the user with sense holiness. Keywords: Mosque, Light, Islamic architecture, Pakistan, Lahore, Masjid Wazir Khan.

Reconfigurable Origami Transparent Cellulose Triboelectric Paper for Multi‐modal Energy Harvesting

AbstractFacile integration of foldability, transparency, and waterproofness in multi‐modality triboelectric nanogenerator (TENG) applications is interesting. Here, we realized a reconfigurable origami transparent cellulose electronic paper (CEP) as TENG for energy harvesting from water, wind, and human motion. A unique silver nanowires‐bundle mesh (AgBM) was embedded into a micron‐thick ethyl cellulose paper by spraying and transfer process. Operating in single‐electrode mode, the CEP‐TENG can harvest energy from human motions by tapping, scavenge wind energy via mechanical interaction, as well as harvest energy from water, including acidic and alkaline water in virtue of protection by an extra hydrophobic cellulose oleoyl ester nanocoating. Origami capability enables the CEP‐TENG to be reconfigurable in three‐dimensional mode to maximize the energy harvesting efficiency. The CEP‐TENG energy window was demonstrated under the flowing water to achieve a self‐powered lighting display. CEP‐TENG realizes the all‐weather and multi‐modality energy harvesting, promising for wearable and attachable power sources, self‐powered applications such as outdoor displays, windows, decorative accessories, and life‐saving appliances.

Flexoelectric-effect-based light waveguide liquid crystal display for transparent display

We report a light waveguide liquid crystal display (LCD) based on the flexoelectric effect. The display consists of two parallel flat substrates with a layer of flexoelectric liquid crystal sandwiched between them. A light-emitting diode (LED) is installed on the edge of the display and the produced light is coupled into the display. When no voltage is applied, the liquid crystal is uniformly aligned and is transparent. The incident light propagates through the display by total internal reflection at the interface between the substrate and air, and no light comes out of the viewing side of the display. The display appears transparent. When a voltage is applied, the liquid crystal is switched to a micrometer-sized polydomain state due to flexoelectric interaction and becomes scattering. The incident light is deflected from the waveguide mode and comes out of the viewing side of the display. We achieved thin-film-transistor active matrix compatible driving voltage by doping liquid crystal dimers with large flexoelectric coefficients. The light waveguide LCD does not use polarizers as in conventional LCDs. It has an ultrahigh transmittance near 90% in the voltage-off state. It is very suitable for transparent display, which can be used for head-up display and augmented reality display.

From Collaborative Habituation to Everyday Togetherness: A Long-Term Study of Use of the Messaging Kettle

We present a long-term study of use of the Messaging Kettle, an Internet of Things (IOT) research prototype that augments an everyday kettle with both sensing and messaging capability and a beautiful light display in order to investigate connecting geographically distant loved ones to their family through the routine of boiling the kettle. Connection at a distance has been of sustained interest to the CHI community, and the social connection of older people is of increasing importance in recognition of ageing populations globally. However, very few novel designs in this domain have been investigated in situ or over the long term to examine whether their use sustains, and if so, how they impact communication in a relationship. The Messaging Kettle was trialled with four pairs of dispersed older mothers and adult daughters over timeframes that lasted between two months to more than two years. We observed the phenomenon ofcollaborative habituationwherein each party creatively made the technology work for them both through a combination of the gradual transformation of their everyday practices, arrangements, and living. Through developing these joint practices over time, participants expressed feelings ofeveryday togethernessthat nurture their relationship at a distance. Three of the four couples continued to use the prototype for years, beyond the initial trial. We reflect on the artful integration of features of the Messaging Kettle and the way in which these features supportedcollaborative habituation. We also reflect on lessons and implications for the design of such relational technologies.

Terrestrial Microwave Power Beaming

This paper establishes the practicality of terrestrial microwave power beaming at distances >1 km. To beam microwave power along the surface of the earth, it is necessary to consider and, where possible, exploit the effects of microwave propagation across terrain. Key design considerations include the effect of scattering from surface topography, approaches for characterizing the beam in the presence of multipath, safety, and efficiency. A rapid demonstration at the US Army Research Field in Blossom Point, MD, delivers 1.6 kW of electrical power at a 1046 m standoff from a 5.4-m-diameter X band transmitter. The transmitter is a reflector antenna with a linearly actuated feed horn that can focus the power density at specific standoff distances. Experimental results over cluttered, irregular terrain achieve a 2.3 dB (70%) enhancement in power density at the target site by deliberate exploitation of a ground bounce. A 4 m² rectenna receiver produces the 1.6 kW of output power at a 73% RF-to-DC conversion efficiency, which exceeds the current state of the art at X band. In addition, a test to destruction of 4 large rectenna arrays demonstrates how overvoltage protection circuits can improve the RF power handling of rectenna arrays by >1 dB. A final experiment demonstrates >1 kW delivered at >1 km distance to a light display. Since these results should readily scale to higher levels of power and performance, recommendations are provided to mature the technology for operational use.

Project starline

We present a real-time bidirectional communication system that lets two people, separated by distance, experience a face-to-face conversation as if they were copresent. It is the first telepresence system that is demonstrably better than 2D videoconferencing, as measured using participant ratings (e.g., presence, attentiveness, reaction-gauging, engagement), meeting recall, and observed nonverbal behaviors (e.g., head nods, eyebrow movements). This milestone is reached by maximizing audiovisual fidelity and the sense of copresence in all design elements, including physical layout, lighting, face tracking, multi-view capture, microphone array, multi-stream compression, loudspeaker output, and lenticular display. Our system achieves key 3D audiovisual cues (stereopsis, motion parallax, and spatialized audio) and enables the full range of communication cues (eye contact, hand gestures, and body language), yet does not require special glasses or body-worn microphones/headphones. The system consists of a head-tracked autostereoscopic display, high-resolution 3D capture and rendering subsystems, and network transmission using compressed color and depth video streams. Other contributions include a novel image-based geometry fusion algorithm, free-space dereverberation, and talker localization.

Structure, optical characteristics and temperature sensing performance studies of Cs3YF6: Er3+, Yb3+ up-conversion material with cryolite structure

Cryolite has been considered as an appropriate host for up-conversion materials due to its low phonon energy, wide light transmission range, easy to form waveguide and stable structure. In this paper, a series of up-conversion materials Cs3YF6: Er3+, Yb3+ with cryolite structure were prepared by high-temperature solid-phase method. The structure, morphology, element composition and up-conversion luminescence properties of as-prepared samples were characterized. In addition, the number of photons absorbed during the up-conversion process and the possible up-conversion luminescence mechanism are analyzed in detail. Under the excitation of 980 ​nm, the Cs3YF6: Er3+, Yb3+ sample emits strong green light visible to the naked eye. Simultaneously, the maximum absolute sensitivity (Sa) and relative sensitivity (Sr) were calculated. All the results indicated that Cs3YF6: Er3+, Yb3+ has potential applications in the fields of green light display and temperature sensing.

Effect of Tb3+ ion concentration on the up-conversion and down-conversion luminescence properties of the Yb3+/Ho3+/Tb3+ tri-doped SiO2–Al2O3–Y2O3–NaF–CaF2 glasses

Yb 3+ -Ho 3+ -Tb 3+ co-doped SiO 2 –Al 2 O 3 –Y 2 O 3 –NaF–CaF 2 glasses were prepared. The XRD of the glass was obtained, which proved the amorphous state of the glass. The crystallization temperature of glass was measured by differential scanning calorimetry, and the crystallization activation energy was obtained. The absorption spectrum of glass was investigated. The network structure of glass was studied. The up-conversion and down-conversion spectra of the glass were obtained under 980 nm and 369 nm excitation, respectively, and the fluorescence decay lifetime of Tb 3+ : 5 D 4 was measured. The influence of laser power on up-conversion luminescence intensity was investigated by changing the laser power. The energy transfer relationship among Yb 3+ , Ho 3+ , and Tb 3+ was researched. The CIE chromaticity coordinate was calculated according to the emission spectrum. It shows that this series of glasses have possible applications in the field of the green light display. • Yb 3+ -Ho 3+ -Tb 3+ tri-doped SiO 2 –Al 2 O 3 –Y 2 O 3 –NaF–CaF 2 glass was prepared. • Intensity of the up-conversion and down-conversion emission peaks was dominated by Tb 3+ ions. • Energy level transitions and energy transfer modes between Yb 3+ -Ho 3+ -Tb 3+ ions were discussed. • This series of glass has potential applications in the field of green light display elements.

Light Effect, Color Applications and Composition in Ustad Nasrullah Sarwary Arts

This research pays for Ustad Nasrullah Sarwary arts’ characteristic one of Afghanistan modern painters in which analysis light display workout, color application and composition in his arts. The aim of this research it the cognition and introduction of specifications and hidden artistic and scientific points in Sarwary arts. The importance of this research is to introduce specification of one of skillful painters who was not known in art. The results show that Prof. Sarwary was successful to combine classism, naturalism and impressionism and make his own unique method. He also could make ideal space of light effect display and application of basic geometry in his art composition. Art students in Herat and Kabul Art Faculties can make the best of use of this research results as their study complementariness and also increase social knowledge level about an Afghan painter work specification (Sarwary).