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One major problem in the lighting industry is the thermal management of the devices. Handling of thermal resistance from solder point to the ambiance of the light-emitting diode (LED) package is linked to the external thermal management that includes a selection of the cooling mode, design of heatsink/substrate and thermal interface material (TIM). Among the significant factors that increase the light output of the of the LED system are efficient substrate and TIM. In this work, the influence of TIM on the luminous flux performance of commercial indium gallium aluminium phosphide (InGaAlP) low-power (LP) LEDs was investigated.

One batch of LEDs was mounted directly onto substrates which were glass-reinforced epoxy (FR4) and aluminium-based metal-core printed circuit boards (MCPCBs) with a dielectric layer of different thermal conductivities. Another batch of LEDs was prepared in a similar way, but a layer of TIM was embedded between the LED package and substrate. The TIMs were thermally conductive epoxy (TCE) and thermally conductive adhesive (TCA). The LED parameters were measured by using the integrated system of thermal transient tester (T3Ster) and thermal-radiometric characterization of LEDs at various input currents.

With the employment of TIM, the authors found that the LED’s maximum luminous flux was significantly higher than the value mentioned in the LED datasheet, and that a significant reduction in thermal resistance and junction temperature was revealed. The results showed that for a system with low thermal resistance, the maximum luminous flux appeared to occur at a higher power level. It was found that the maximum luminous flux was 24.10, 28.40 and 36.00 lm for the LEDs mounted on the FR4 and two MCPCBs, respectively. After TCA application on the LEDs, the maximum luminous flux values were 32.70, 36.60 and 37.60 lm for the FR4 and MCPCBs, respectively. Moreover, the findings demonstrated that the performance of the LED mounted on the FR4 substrate was more affected by the employment of the TIM than that of MCPCBs.

One of the major problems in the lighting industry is the thermal management of the device. In many low-power LED applications, the air gap between the two solder pads is not filled up. Heat flow is restricted by the air gap leading to thermal build-up and higher thermal resistance resulting in lower maximum luminous flux. Among the significant factors that increase the light output of the LED system are efficient substrate and TIM.

The findings in this work can be used as a method to improve thermal management of LP LEDs by applying thermal interface materials that can offer more efficient and brighter LP LEDs. Using aluminium-based substrates can also offer similar benefits.

Users of LP LEDs can benefit from the findings in this work. Brighter automotive lighting (signalling and backlighting) can be achieved, and better automotive lighting can offer better safety for the people on the street, especially during raining and foggy weather. User can also use a lower LED power rating to achieve similar brightness level with LED with higher power rating.

Better thermal management of commercial LP LEDs was achieved with the employment of thermal interface materials resulting in lower thermal resistance, lower junction temperature and brighter LEDs.

It is important to monitor wrist four direction movements (flexion, extension, adduction and abduction) for hand healthcare, wrist rehabilitation and upper limb exercise, and so on. The purpose of this study is to develop a quadri-directional optical bending sensor that integrated wearable device technology in a smart glove to detect wrist four direction movements.

The quadri-directional optical bending sensor was designed with a microcontroller board, a Bluetooth wireless module, a side-emitting polymeric optical fibre (POF), an infrared light emitting diode and four phototransistors. A linear equation was deduced to calculate bending angle from detecting sensor value of Arduino microcontroller. The bending angle values could be seen by the smartphone screen, so the system has a good human–machine interface function.

The light emission by macro-bending of the side-emitting POFs that the transmittance of the outer side is greater than the inner. The bending POFs lateral emission phenomenon integrated with phototransistors on the edge is suitable for the development of bending sensors.

This study is to develop a novel quadri-directional optical bending sensor to replace two bi-direction sensors or four uni-direction sensors for wrist four direction movements monitoring.

At The Institute of Physical and Chemical Research (RIKEN) a new process named multiple LED photographic curing (MPC) has been developed. As a matter of priority, MPC is thought to be applied to concept modelling. The building data are available in bitmap or voxel representation respectively. In MPC, light is generated by light‐emitting diodes (LEDs). Exposing of a photopolymer happens through raster scanning. An array of multiple beams of light is projected onto the resin surface while the scan head moves across the vat. The fabrication of test parts has proven the system’s practical ability to create geometric objects. Surface finish is quite good, certainly adequate for most concept verification. Some obstacles such as low exposure energy have yet to be overcome. Scaling up the build envelope enables fabricating much larger parts.

The purpose of this paper is to present and discuss the results of measurements illustrating influence of the area of a thermal pad and the kind of the used base on thermal and optical parameters of LED modules.

LED modules including six power LEDs are designed. In the layout of these modules, different areas of a thermal pad of each LED are used. These modules are made using the classical FR-4 base and metal core printed circuit board (MCPCB). Thermal and optical parameters of all the tested modules are measured using the method elaborated by the authors.

The obtained results of measurements prove that increasing the area of a thermal pad causes a decrease in thermal resistance of the tested LED modules and an increase in power density of the emitted light. The role of the area of a thermal pad is more important for the classical FR-4 base than for MCPCB.

Investigations were performed for only two values of the area of thermal pads and selected values of LEDs forward current.

The presented results of investigations show how the used layout and type of the used base of these modules influence optical and thermal parameters of LED modules. Changing the base of a module can cause even a double decrease in thermal resistance and a double increase in power density of the emitted light.

Describes the benefits that arise from the use of Light Emitting Diodes (LEDs) for illumination in industrial machine vision systems. These include long life, stability and narrow frequency bands. Also discusses precautions that need to be taken for obtaining a uniform illumination and pulsed operation.

The purpose of this paper is to investigate drivers’ differing psychological perceptions of cyclists’ conspicuity according to active visibility aid configurations on clothing.

The flashing light-emitting diodes (FLEDs) were positioned on the major joints (shoulders, elbows, wrists, hips, knees, and ankles) in eight configurations and pre- and post-surveys were conducted.

The results indicated that there were significant differences among the eight configurations in observers’ detection and recognition of cyclists, contributions of FLEDs, and visibility of cyclists (p<0.001). Among the eight different configurations on joints, FLEDs on the hips, knees, and ankles were the most detectable, recognizable, and visible.

Most of the previous studies have investigated passive visibility aids and there is a lack of research on FLED configurations on major joints for cyclists. Thus, this study is expected to be beneficial to designers when developing active visibility aid clothing for cyclists.

The recent surge in light emitting diode (LED) lighting retrofitted into schools in the UK is as a result of the UK Government’s 2050 zero carbon pledge. However, the benefits and consequences of LED retrofit projects for staff and enablers and stakeholder knowledge gaps about LED lighting retrofitting have not been fully explored. The aim of this research is to determine the amount of savings in cost, carbon reduction and kilowatt usage and to confirm if repayment from energy and cost savings derived from LED retrofit school projects funded through the SALIX funding option in the UK would be enough to service the loan. Thus, it examines monetary and non-monetary benefits, internal project stakeholder knowledge gaps and the consequences of LED retrofit for the staff and enablers of a large community college in the UK which is funded through the SALIX funding option.

The methodology relied on a hybrid research approach of a case secondary school through the review of literature, analysis of secondary data, focus group and questionnaire survey. The focus group consists of six key project stakeholders. The secondary data was sourced from the Project IGP [Individual Grade Proposal] and the Positive Energy Report from Zenergi, and the closed online questionnaire survey was used to sample 150 teaching staff and school enablers.

The findings show that stakeholders lack project knowledge, trust and expertise/project comprehension. This is in terms of baseline information, LED technology/management, payback modalities, management of risks and ethical issues around environmental impact. The forecasted SALIX savings were not achieved in real-time, partly because it does not take into consideration the increase in energy costs over the payback period. However, the LED retrofit creates efficiencies; drives down energy costs and energy usage; and drives carbon reduction, helping pupils’ learning, improving productivity and performance, and finally leading to a better lighting environment for the school community.

The study will help schools in the UK that intend to access SALIX finance for LED retrofits to understand the challenges and mitigate the risks. It will also help the government to understand the importance of adjusting the payback modalities to the base price when the retrofit was carried out for real-time savings to be made. The research would be useful in ensuring the proactive involvement of all the identified stakeholders in understanding the challenges and what the function entails.

The purpose of this paper is to use a series of disruptive innovations in the 150‐year history of the US lighting industry to test whether two key innovation management theories retain their explanatory power as market structures change.

Historical case studies of four successive disruptive lighting innovations are used: incandescent light bulbs, fluorescent light bulbs, compact fluorescent light bulbs (CFBs) and light emitting diodes (LEDs). Descriptions of each innovation include the new technologies, the evolving market structures, and how the innovating companies managed their risks during the transitions.

This paper finds that two contemporary theories on absorptive capacity and disruptive innovations retain validity and remain broadly applicable even as market structures change overtime from oligopoly and cartel to free market competition.

By juxtaposing historic incandescent and fluorescent bulb innovations in constrained market conditions with modern CFB and LED innovations in free market conditions, this paper expands understanding of the lighting history to include the past two decades. It also expands the applicability of innovation theories by showing that they apply to various and changing market structures.

This paper aims to present the results of the influence of a manner of soldering light emitting diodes (LEDs) to the metal core printed circuit board on thermal parameters of the module LED containing these diodes.

Using the authors’ elaborated measuring method and the dedicated measurement set-up, transient thermal impedances of LED modules, mounted using different soldering processes and mounted to the heat-sink with different values of the moment of force, are measured. The obtained results of measurements are discussed.

It was shown experimentally that the manner of soldering could strongly influence efficiency of dissipation of heat generated in the module. The best thermal properties were obtained for soldering using vapour phase technology with vacuum and paste LFS-216LT. It was also proved that the moment of force used while mounting the considered modules on the heat-sink can result in a change of the value of thermal resistance of this module exceeding even 12 per cent.

The investigations were performed for five LED modules operating at one, arbitrarily selected value of power dissipated in these modules mounted on the heat-sink of arbitrarily selected dimensions.

The obtained results of measurements could be usable for designers of mounting processes of power LED modules.

This paper presents the results of investigations of thermal properties of LED modules, in which different techniques of soldering are used. It was shown experimentally that the manner of soldering could strongly influence efficiency of dissipation of heat generated in the module. It was also proved that the moment of force used while mounting the considered modules on the heat-sink is important.

The purpose of this paper is to realize an electronic circuit design on the fabric surfaces to form a fully integrated functional active T‐shirt structure.

Functional products combining textile, electronics and the software have attracted great attention in recent years. The integration of the electrical and electronic devices on the garment surface using conductive threads is a challenging issue considering conductiveness, long durability, washability and manufacturing process. As an application, a group of light emitting diode (LED) lights controlled by a light sensor, accelerometer and related electronic control circuits were placed on a fabric construction.

The brightness of LED lights is controlled by using a light sensor depending on the perceived ambient light intensity. LED lighting patterns are controlled by means of an accelerometer which senses the physical activities of the wearer, such as walking, running and standing.

In this study, new construction methods have been successfully implemented and the active T‐shirt has been realized with its related hardware and software.