Design, Fabrication, and Testing of a Novel Design for Flexible Light-Emitting Diode Signage Modules

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Ram C. Adhikari ◽  
Dawood S. Beyragh ◽  
Majid Pahlevani
Keyword(s):  
Printed Circuit Boards ◽  
Maximum Stress ◽  
Experimental Testing ◽  
Light Emitting Diode ◽  
Flexible Substrate ◽  
Internal Stresses ◽  
Curved Surfaces ◽  
Standard Size ◽  
Light Emitting ◽  
Wide Range

Abstract This paper presents a new design architecture for mechanically flexible light-emitting diode (LED) signage modules for applications in digital advertising on curved surfaces. The new design comprises an array of commonly used rigid printed circuit boards (PCBs) but of smaller size with some spacing between them, which is encapsulated by a flexible substrate or potting material, instead of a large single rigid PCB in the entire LED module as in the case of conventional LED signage modules. Commonly used through-hole type red-green-blue (RGB) LEDs are considered. To demonstrate the design, manufacturing, and mechanical flexibility of the design, a prototype LED signage module with a typical industry standard size of 304 mm × 304 mm × 10 mm was designed and fabricated. Experimental testing and finite element simulations were conducted to analyze mechanical flexibility and internal stresses in the module. The results demonstrate that the new design provides flexible LED modules, without altering the conventional LED control system. It is shown that maximum stress occurs in the spacing between the PCBs and is small even for large module deflection. As the curvature of module deflection was decreased, the maximum stress increased, indicating an important design parameter for the module deflection. The proposed design architecture will enable both indoor and outdoor digital advertising using billboards on a wide range of curved surfaces.

scholarly journals LED Rail Signals: Full Hardware Realization of Apparatus with Independent Intensity by Temperature Changes

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1291
Author(s):  
Giuseppe Schirripa Schirripa Spagnolo ◽  
Fabio Leccese
Keyword(s):  
Temperature Sensor ◽  
Energy Efficient ◽  
Light Emitting Diode ◽  
Junction Temperature ◽  
Light Emitting ◽  
Temperature Changes ◽  
Wide Range ◽  
International Regulations ◽  
Long Lifetime ◽  
Set Up

Nowadays, signal lights are made using light-emitting diode arrays (LEDs). These devices are extremely energy efficient and have a very long lifetime. Unfortunately, especially for yellow/amber LEDs, the intensity of the light is closely related to the junction temperature. This makes it difficult to design signal lights to be used in naval, road, railway, and aeronautical sectors, capable of fully respecting national and international regulations. Furthermore, the limitations prescribed by the standards must be respected in a wide range of temperature variations. In other words, in the signaling apparatuses, a system that varies the light intensity emitted according to the operating temperature is useful/necessary. In this paper, we propose a simple and effective solution. In order to adjust the intensity of the light emitted by the LEDs, we use an LED identical to those used to emit light as a temperature sensor. The proposed system was created and tested in the laboratory. As the same device as the ones to be controlled is used as the temperature sensor, the system is very stable and easy to set up.

scholarly journals ZnO Microcrystals for Light Emitting Diode and Photovoltaic Applications with Integration on Flexible Substrates

2009 ◽  
Vol 1192 ◽  
Author(s):  
Jesse J Cole ◽  
Heiko Jacobs
Keyword(s):  
Flexible Electronics ◽  
Light Emitting Diode ◽  
Flexible Substrate ◽  
Oxygen Plasma Treatment ◽  
Near Band Edge ◽  
Transfer Printing ◽  
Light Emitting ◽  
Integration Approach ◽  
Photovoltaic Applications

AbstractWe report a new integration approach to produce arrays of ZnO microcrystals for optoelectronic and photovoltaic applications. Demonstrated applications are n-ZnO/p-GaN heterojunction LEDs and photovoltaic cells. The integration process uses an oxygen plasma treatment in combination with a photoresist pattern on Magnesium doped GaN substrates to define a narrow sub-100nm width nucleation region. ZnO is synthesized in the defined areas by a hydrothermal technique using zinc acetate and hexamethylenetetramine precursors. Nucleation is followed by lateral epitaxial overgrowth producing single crystal disks of ZnO. The process provides control over the dimension and location of the ZnO crystals. The quality of the patterned ZnO is high; the commonly observed defect related emission in the electroluminescence spectra is suppressed and a single near-band-edge UV peak is observed. Transfer printing of the ZnO microcrystals onto a flexible substrate is also demonstrated in the context of transparent flexible electronics.

Thermal Performance of a Light Emitting Diode Light Engine for a Multipurpose Automotive Exterior Lighting System With Competing Board Technologies

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Umut Zeynep Uras ◽  
Mehmet Arık ◽  
Enes Tamdoğan
Keyword(s):  
Thermal Performance ◽  
Computational Models ◽  
Printed Circuit Boards ◽  
Light Emitting Diode ◽  
Ambient Conditions ◽  
Vapor Chamber ◽  
Metal Core ◽  
Light Emitting ◽  
Lighting Systems ◽  
Light Engine

In recent years, light emitting diodes (LEDs) have become an attractive technology for general and automotive illumination systems replacing old-fashioned incandescent and halogen systems. LEDs are preferable for automobile lighting applications due to its numerous advantages such as low power consumption and precise optical control. Although these solid state lighting (SSL) products offer unique advantages, thermal management is one of the main issues due to severe ambient conditions and compact volume. Conventionally, tightly packaged double-sided FR4-based printed circuit boards (PCBs) are utilized for both driver electronic components and LEDs. In fact, this approach will be a leading trend for advanced internet of things applications embedded LED systems in the near future. Therefore, automotive lighting systems are already facing with tight-packaging issues. To evaluate thermal issues, a hybrid study of experimental and computational models is developed to determine the local temperature distribution on both sides of a three-purpose automotive light engine for three different PCB approaches having different materials but the same geometry. Both results showed that FR4 PCB has a temperature gradient (TMaxBoard to TAmbient) of over 63 °C. Moreover, a number of local hotspots occurred over FR4 PCB due to low thermal conductivity. Later, a metal core PCB is investigated to abate local hot spots. A further study has been performed with an advanced heat spreader board based on vapor chamber technology. Results showed that a thermal enhancement of 7.4% and 25.8% over Al metal core and FR4-based boards with the advanced vapor chamber substrate is observed. In addition to superior thermal performance, a significant amount of lumen extraction in excess of 15% is measured, and a higher reliability rate is expected.

scholarly journals Spectroscopy Transmittance by LED Calibration

Sensors ◽  
2019 ◽  
Vol 19 (13) ◽  
pp. 2951 ◽  
Author(s):  
Daniel Carreres-Prieto ◽  
Juan T. García ◽  
Fernando Cerdán-Cartagena ◽  
Juan Suardiaz-Muro
Keyword(s):  
Real Time ◽  
Light Emitting Diode ◽  
Research Work ◽  
Cost Effective ◽  
Spectral Width ◽  
Calibration Procedure ◽  
Pollution Monitoring ◽  
Light Emitting ◽  
Wide Range ◽  
Incandescent Lamps

Local administrations demand real-time and continuous pollution monitoring in sewer networks. Spectroscopy is a non-destructive technique that can be used to continuously monitor quality in sewers. Covering a wide range of wavelengths can be useful for improving pollution characterization in wastewater. Cost-effective and in-sewer spectrophotometers would contribute to accomplishing discharge requirements. Nevertheless, most available spectrometers are based on incandescent lamps, which makes it unfeasible to place them in a sewerage network for real-time monitoring. This research work shows an innovative calibration procedure that allows (Light-Emitting Diode) LED technology to be used as a replacement for traditional incandescent lamps in the development of spectrophotometry equipment. This involves firstly obtaining transmittance values similar to those provided by incandescent lamps, without using any optical components. Secondly, this calibration process enables an increase in the range of wavelengths available (working range) through a better use of the LED’s spectral width, resulting in a significant reduction in the number of LEDs required. Thirdly, this method allows important reductions in costs, dimensions and consumptions to be achieved, making its implementation in a wide variety of environments possible.

Tri-Metal Layered Semitransparent Electrode for Red Phosphorescent Organic Light-Emitting Diodes

2015 ◽  
Vol 15 (10) ◽  
pp. 8144-8148 ◽  
Author(s):  
Jae Woo Lee ◽  
Ho Won Lee ◽  
Song Eun Lee ◽  
Hyung Jin Yang ◽  
Sung Kyu Lee ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Glass Substrate ◽  
Light Emitting Diode ◽  
Metal Layer ◽  
Flexible Substrate ◽  
Flexible Display ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light Emitting Diode ◽  
Organic Light

In this paper, we fabricated tri-metal layered thin film semitransparent electrodes consisting of a thin conductive metal layer, sandwiched between two nickel layers. An equal red phosphorescent organic light-emitting diode (PHOLED) structure was deposited on the anodes of indium tin oxide (ITO) and three types of tri-metal layers (Ni/Al/Ni, Ni/Cu/Ni, and Ni/Ag/Ni, thickness of 3/7/3 nm in common) on a glass substrate. The optical and electrical performances of the device using Ni/Ag/Ni were improved more than the performances of the other devices due to the micro-cavity effect in accordance with the various electrode characteristics. Moreover, we fabricated the same red PHOLED structures on a flexible substrate, as a consequence, showed competitive emission characteristics compared to the devices fabricated on a glass substrate. Therefore, this study could succeed to additional research on flexible display panel and light-emitting devices with ITO-free electrodes.

A High Efficiency Step-Up WLED Driver with Wide Range PWM Dimming

2012 ◽  
Vol 588-589 ◽  
pp. 884-887
Author(s):  
Fei Xu ◽  
Le Nian He
Keyword(s):  
Pulse Width Modulation ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
System Efficiency ◽  
Current Sensing ◽  
Light Emitting ◽  
Wide Range ◽  
Simulation Results ◽  
Peak Value ◽  
Pwm Dimming

A high efficiency step-up White Light Emitting-diode (WLED) driver with PWM dimming is presented in this paper. An integrated current sensing technique is used to improve system efficiency. Meanwhile, a novel PWM(pulse width modulation) dimming scheme is proposed to achieve wide range dimming frequency, which can be adaptive to dimming frequency from 200Hz to 200 KHz. The proposed driver is designed with CSMC 0.5um 40V bipolar-CMOS-DMOS process. Simulation results verify the functionality of the design and high efficiency is realized, with a peak value of 94.12% at 5.5V-input and 200mA-load.

scholarly journals Light-Emitting Diode Based Photoacoustic Imaging System

2020 ◽  
Author(s):  
Ebrahim Najafzadeh ◽  
Parastoo Farnia ◽  
Alireza Ahmadian ◽  
Hossein Ghadiri
Keyword(s):  
Imaging System ◽  
Photoacoustic Imaging ◽  
Light Emitting Diode ◽  
Imaging Modality ◽  
Optical Excitation ◽  
Poly Vinyl Alcohol ◽  
Ultrasound Images ◽  
Light Emitting ◽  
Non Invasive ◽  
Wide Range

Purpose: A Photoacoustic Imaging (PAI) as a non-invasive hybrid imaging modality has the potential to be used in a wide range of pre-clinical and clinical applications. There are different optical excitation sources that affect the performance of PAI systems. Our goal is proving the capability of the Light-Emitting Diode (LED) based PAI system for imaging of objects in different depths. Materials and Methods: In this study the Full Width of Half Maximum (FWHM) and Contrast to Noise Ratio (CNR) of LED-based PAI system is evaluated using agar, and Poly-Vinyl Alcohol Cryogel (PVA-C) phantoms. Results: The results show that axial and lateral FWHM of the photoacoustic image in agar phantom 1%, are 0.59 and 1.16 mm, respectively. It is capable of distinguishing objects about 250 µm. Furthermore, one of the main improvements of photoacoustic images is achieved by proposed LED-based system that is a 26% higher CNR versus the ultrasound images. Conclusion: Therefore, the provided technical characteristics in this study have made designed LED-based PAI system as a suitable tool for preclinical and clinical imaging.

Towards a Novel Broadband Spectrally Dynamic Solid State Light Source

2005 ◽  
Vol 892 ◽  
Author(s):  
David Nicol ◽  
Shalini Gupta ◽  
Nola Li ◽  
Ali Asghar ◽  
Elton Graugnard ◽  
...  
Keyword(s):  
Solid State ◽  
Real Time ◽  
Light Source ◽  
Tunnel Junction ◽  
Light Emitting Diode ◽  
Contact Layer ◽  
Light Emitting ◽  
Wide Range ◽  
Multiple Wavelengths ◽  
Dynamic Source

AbstractThe developments of two major components of a three terminal dual wavelength LED for excitation of multiple phosphors are described. Such a configuration will be novel Broadband Spectrally Dynamic Light Emitting Diode (BSDLED). First, work towards a functional tunnel junction in the GaN system is discussed. The developments of p+ and n+ GaN layers are specifically discussed in relation to their use in a buried current spreading contact layer. Second, the analysis of several phosphors and their application in a spectrally dynamic source is explored. The response to multiple wavelengths of the phosphors is analyzed to create a light source that can be tuned in “real time” to a wide range of correlated color temperatures.

scholarly journals Low-cost photoacoustic imaging systems based on laser diode and light-emitting diode excitation

2017 ◽  
Vol 10 (04) ◽  
pp. 1730003 ◽  
Author(s):  
Qingkai Yao ◽  
Yu Ding ◽  
Guodong Liu ◽  
Lvming Zeng
Keyword(s):  
Laser Diode ◽  
Near Infrared ◽  
Photoacoustic Imaging ◽  
Light Emitting Diode ◽  
Imaging Modality ◽  
Low Cost ◽  
Laser System ◽  
Great Promise ◽  
Light Emitting ◽  
Wide Range

Photoacoustic imaging, an emerging biomedical imaging modality, holds great promise for preclinical and clinical researches. It combines the high optical contrast and high ultrasound resolution by converting laser excitation into ultrasonic emission. In order to generate photoacoustic signal efficiently, bulky Q-switched solid-state laser systems are most commonly used as excitation sources and hence limit its commercialization. As an alternative, the miniaturized semiconductor laser system has the advantages of being inexpensive, compact, and robust, which makes a significant effect on production-forming design. It is also desirable to obtain a wavelength in a wide range from visible to near-infrared spectrum for multispectral applications. Focussing on practical aspect, this paper reviews the state-of-the-art developments of low-cost photoacoustic system with laser diode and light-emitting diode excitation source and highlights a few representative installations in the past decade.

Optical fibre systems

1978 ◽  
Vol 289 (1356) ◽  
pp. 135-150 ◽  
Keyword(s):  
Semiconductor Lasers ◽  
Optical Fibre ◽  
Light Emitting Diode ◽  
Beam Quality ◽  
Single Mode ◽  
Laser Source ◽  
Fibre Strength ◽  
Optical Source ◽  
Light Emitting ◽  
Wide Range

The present state of research and development into optical fibre systems for applications in telecommunications is reviewed and some of the principal problems remaining are discussed. Attenuations close to the intrinsic limits of the materials available have been reached in laboratory fibres and losses in optical cables installed under normal working conditions are below 5 dB/km. Bandwidths available range from 20 MHz km, in step-index multimode fibres with light emitting diode sources, to 10 GHz km with single-mode fibres and semiconductor lasers. If a truly monochromatic laser source operating in the region of minimum material dispersion becomes available then individual fibre capacities up to, or beyond, 100 GHz km are feasible. The major problems in cabling have already been largely overcome but further improvements in fibre strength, homogeneity and reproducibility are awaited. The difficulties are technological rather than fundamental and will succumb to good innovative engineering within the next few years. The same may be said of the requirements for such mundane, but vitally important, components as splices, connectors, couplers and even the lowly jack plug. Excellent and encouraging progress is being made with all of these items. Of the major hurdles remaining, that of a suitable optical source is by far the most difficult. The lifetime and reliability of existing semiconductor lasers are improving only slowly and need to be increased by at least an order of magnitude. It would also be an advantage if their line width, coherence and beam quality could be made to approximate more closely those of an ideal laser. Fortunately light emitting diodes can also be used if adequate lasers do not become available, but at the expense of system bandwidth and repeater spacing. Technological forecasting is fraught with hazards for the unwary but it is reasonable to expect systems to be operating in the telephone network in the 1980s at capacities from 140 Mbit/s to 500 Mbit/s at repeater spacings of at least 5 km and perhaps as high as 20 km. Serious study of the application of optical fibres to underwater cables will also have begun. If simple fibre cables can be made cheaply enough for use in installations to individual subscribers a wide range of new developments become possible, but these problems are more relevant to the 1990s.

Sign in / Sign up

Export Citation Format

Share Document