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A generic red, green, and blue (RGB) LED system encompasses complex interactions of power, heat, light, and color, which pose a major challenge for achieving precise control over luminance and color-mixing in high-quality lighting applications. In this article, new nonlinear empirical models of a practical RGB LED system with closed-loop control are formulated. They enable precise prediction of luminous flux and color coordinates by using the three distinct reference voltages as the control variables for independent current regulation across the RGB LED strings. The proposed empirical models are experimentally verified by using a hardware prototype of a dc–dc single-inductor three-output LED driver with proportional–integral compensators and time-interleaving control scheme. The measured values of luminous flux and color coordinates agree closely with the predicted values from the models.

Stable color converters exhibiting high color rendering index have drawn researchers’ attention for their applications in high-quality white laser lighting. In this study, we develop the multi-color phosphor-in-glass (PIG) with the weight ratio of green-emitting (Y3Al3.08Ga1.92O12:Ce3+) to red-emitting (CaAlSiN3:Eu2+) phosphor powders (10/1–18/1) by low temperature co-sintering method. The obtained composite material displays an outstanding optical and thermal performance, including a high internal quantum efficiency of 84.2%, a high transparency of 45% in the visible region and a low thermal quenching (it remains 86% at 448 K). By integrating 450 nm blue laser diodes with optimized multi-color PIG, the white light with a maximum luminous flux of 258 lm and a luminous efficiency of 137 lm/W is achieved for the first time. Additionally, considering the white balance, by tailoring the weight ratio of green-emitting to red-emitting phosphor and the thickness of PIG, the 14/1 PIG at fixed thickness of 0.75 mm produces pure white light with ultra-high color rendering index of 95.2 and a high luminous efficiency of 120.9 lm/W under power density of 2.39 W/mm2 irradiation. The above superior characteristics imply that the multi-color PIG is an ideal candidate for high-quality white laser lighting applications.

The complaints, worries and dissatisfactions accrued to bulb users prompted the quest of this research. The objective of the research is to suitably assess few electrical parameters of bulbs available in the market in order to have an experimental proof of the disparity in their ratings. In the research experimental data, incandescent bulbs (100W and 200W), LED bulb (5W) and CFL bulb (40W) (of different powers) were selected for evaluation. The power and lux of the bulbs were measured and compared correspondingly using the incandescent bulbs as reference bulbs for lux comparison. The new double T8 full range & ac/dc power meter with dimmer was instrument used to measure power and other associated electrical parameters (current and voltage) of the bulbs. The measurement results show that incandescent bulb of 100W measured 60.1W and the 200W measured 184.0W. The power of the 5W LED and 40W CFL bulbs measured 7.2W and 22.2W respectively. On this note, it is invariably obvious that there exists disparity in power rating of the bulbs accessible in our present day market. The digital luxmetre was used to measure lux (luminous flux per unit area or lumen per metre square) of the bulbs. In the lux measurement, the luxmetre’s sensor was placed 50cm away from the bulb’s position to obtain exact or close values to original bulbs’ lux. Consequential to the bulbs lux comparisons, the lux value of 5W LED and 40W CFL bulbs have illuminances of 507lm/m2 and 568lm/m2 respectively higher than lux of 100W incandescent bulb. Hence, lux values of the LED and CFL bulbs measurements fall in-between lux values of 100W and 200W incandescent bulbs. Critical evaluation of the results tends to establish that luminosity (luminous flux per area) of bulb does not depend on power.

The solar light bulb is a one-liter bottle filled with water that uses the refraction of sunlight. In many places, it is not expected the consumption of 1-liter bottles but other capacities. This study shows the effect of the shape of the PET bottles and how the capacity influences the luminous flux resulting from the solar refraction. A total of nine solar bulb models were used with different shapes and capacities (600 mL, 1 L, and 1.5 L). The results showed no interaction between the two factors where the best luminous flux was obtained using the 1 L and 1.5 L bottles regardless of the shape, ranging from 116 to 143 lux. This outcome expands the variety of PET bottles that can be recycled to build solar light bulbs.

The aim of this study is to investigate a thermally robust white color converter for high-power solid-state lighting, especially laser lighting. Lu3Al5O12:Ce3+/CaAlSiN3:Eu2+ phosphor-in-glass samples (LuAG&CASN-PiGs) were synthesized via a low temperature co-sintering technique. The prepared LuAG&CASN-PiGs exhibited remarkably high internal quantum efficiency of 87 %. Tunable warm white light-emitting diodes (wLED) were acquired by tailoring the sample thicknesses and phosphor contents. The optimized sample showed a high luminous flux of 183.68 lm under a blue laser diodes (LDs). In addition, the chromaticity of white LDs based on the LuAG&CASN-PiGs shifted from cool to warm white by changing the sample thicknesses. High quality white light in wLDs was achieved (Ra＝95). More importantly, the constructed LuAG&CASN-PiG converted LDs with a heat sink exhibited the luminous efficiency of 216.79 lm W−1. The results revealed that the prepared LuAG&CASN-PiG had great potential for application in solid-state laser light sources.

In this paper a novel triple hole block layer (HBL) structure of the OLED is proposed that depicts an enhanced luminescence of 25285 cd/m2 with an improvement of 47% over multilayered OLED architecture. It also owes 74% improvement in luminous power efficiency. An in-depth numerical analysis based on Poisson and drift diffusion equation is undertaken and validated against the internal device analysis. The analysis results highlight an enhanced recombination rate within the proposed device. High electron injection and efficient hole blocking contributes to improved recombination rate. Triple HBL OLED is therefore used for diagnosis of ovarian cancer. The device illustrated good response towards varying wavelengths generating a maximum photo current value of 93 mA. A healthy person can be differentiated from an oncological cancer patient based on fluorescence produced by their urine. The fluorescence values for healthy person and oncological cancer patient are in the range of 420 and 440 nm, correspondingly. The cathode current produced by OLED corresponding to these two wavelengths are 5 and 1 mA respectively. Hence, the proposed device can successfully diagnose the ovarian cancer patient. Further, the methodology proposed for diagnosis of ovarian cancer can help in developing a portable, flexible low cost biomedical sensor.

This article is the analysis of SiO 2 nano-particles’ influences on the luminous efficiency and the color temperature uniformity of a remote phosphor structure in a WLED. The purpose of integrating SiO 2 into the silicone layer in the remote phosphor structure is to significantly promote the scattering occurrences. Particularly, with an appropriate proportion of SiO 2 , there could be more blue lights generated at large angles, leading to reducing the angular-dependent color temperature deviation. The luminous flux also can get benefits from SiO 2 addition owing to a proper air-phosphor layer refractive index ratio provided by this SiO 2 /silicone compound. The attained experimental results were compared with optical values of a non-SiO 2 remote phosphor configuration and showed a notable enhancement. The color deviation was reduced by approximately 600 K in the angles from -70 0 ­ to 70 0 . Additionally, the lumen efficiency was improved by 2.25% at 120 mA driving current. Hence, SiO 2 can be used to boost both color uniformity and luminous efficacy for remote-phosphor WLED.

While the remote phosphor structure is not an appropriate solution for WLED color uniformity, it is more advantageous for the luminous output of WLED than the conformal phosphor or in-cup phosphor structure. Acknowledging the ability of the remote phosphor structure, many studies have been carried out to surmount the color quality disadvantage of this structure. A dual-layer remote phosphor configuration is proposed in this research paper to acquire better color quality for WLEDs through heightening the color rendering index (CRI) and the color quality scale (CQS). The color temperature of the WLED packages this study is 8500 K. By inserting a layer of green CaSO 4 :Ce 3+ ,Mn 2+ or red LiLaO 2 :Eu 3+ phosphor on the yellow YAG:Ce 3+ phosphor layer, the phosphor structure configuration can be constructed. Then, to get the best color quality, the concentration of added phosphor LiLaO 2 :Eu 3+ would be changed. The findings showed the rise of CRI and CQS along with the LiLaO 2 :Eu 3+ , which implies the influence of LiLaO 2 :Eu 3+ to the growth of red light components within WLEDs packages. The greater the concentration of LiLaO 2 :Eu 3+ is, the more the CRI and CQS increase. Meanwhile, the luminous flux gains from the green phosphor CaSO 4 :Ce 3+ ,Mn 2+ . Nevertheless, the luminous flux and color quality would decrease if the concentrations of both red LiLaO 2 :Eu 3+ and green CaSO 4 :Ce 3+ ,Mn 2+ phosphors reach a certain corresponding level. Centered on the Mie-scattering theory and the law of Lambert-Beer, this result is illustrated. The findings in this research are vital references for manufacturing WLEDs with higher white light performance.

The question of the relevance of reducing energy consumption is considered. An assumption is made that in cases where indoor illuminated switches are used that control a group of lamps, currents of the order of microamperes flow in the lighting network in the switched-off mode.The regulatory documentation related to the normative indicators of illumination as well as the typical area of premises is analyzed, and on the basis of the listed data, the calculation of the minimum required luminous flux emitted by lamps is made. The normalized calculated luminous flux was divided by the luminous flux from one lamp, with the resulting ratio rounded up. This ratio is the approximate number of lamps. This number of lamps will enable to calculate the total current of the entire lighting network.The standard rates for the operating time of the lighting network are taken into account. The operating time of the lighting network in the "standby" mode is the difference between the total number of hours per day and the standard operating time of the lighting network.Knowing the power consumption and the network operation time in the "standby" mode, we can calculate the power consumption of the lighting network in the "standby" mode.

In this study, we propose a centrifugation packaging (CP) structure to enhance the optical and thermal dissipation performance of LEDs, using SBA-15 particles to facilitate the sedimentation and dispersion of QDs. The results indicate that the EL spectra of the LEDs remains almost unchanged after the centrifugation time of 60 min and a CP structure can be obtained. The radiation power and luminous flux of LEDs with a CP structure improve by 9.1% and 10.4%, respectively, compared with the uniform distribution (UD) structure. The surface temperature of LED devices with the CP structure is reduced to 34.4 °C from 41.8 °C at a current of 100 mA. Furthermore, the simulation results show that the maximum temperature in the CP structure is 22.4% lower than that in the UD structure at a current of 500 mA. Thus, this study can provide a new perspective for designing settlement structures of QD–LEDs to enhance their optical and thermal performance.

SiO2 nano-particles have been examined in a distant phosphor structure for the elevated luminous quality and better consistency of white light-emitting diodes with angular-dependent associated color temperature (CCT). The luminous scattering ability could be increased by applying SiO2 nano-particles contain silicone to the outside of the phosphorus coating. In specific, the strength of blue light at wide angles is increased and differences in CCT can be minimized. In addition, owing to the sufficient refractive indices of silicone-containing SiO2 nanoparticles between the air and phosphorus layers, the luminous flux was improved. This new configuration decreases angular-dependent CCT deviations in the range of -700 to 700 from 1000 to 420 K. In comparison, at a 120 mA driving current, the rise of lumen flux increased by 2.25% relative to an usual distant phosphor structure without SiO2 nano-particles. As a result, in a distant phosphor structure, the SiO2 nano-particles could not only enhance the uniformity of illumination but also enhance the output of light.

In this research, the SiO2 nano-particles (NPs) usage in enhancing optical performances of InGaN/GaN-based white light-emitting diodes (WLEDs) with remote phosphor structure. The research subject shows better lighting capacity than the white LEDs devices without the space between the layers. The adjustment in development process resulted in enhancements of internal quantum efficiency (IQE) and light extraction efficiency (LEE) that lead to 13.5% luminous efficacy improvement. From the experiments, it can be concluded that the LEE is affected by the trapped light and enhancing the light output with SiO2 scattering properties reduce the amount of trapped light. These results confirm that SiO2 nano-particles is effective in enhancing the optical performance of WLEDs and can be considered for production of higher quality devices.

To achieve high color rendering and proper color temperature, a red color converter is essential for phosphor-converted white lighting devices. CaAlSiN3:Eu2+ (CASN) is a highly suitable red phosphor for white light-emitting diodes. However, it can be hardly used in high-power laser lighting due to poor thermal/chemical performance of the phosphor/silicone resin mixture. A series of all-inorganic CASN-based phosphors (e.g., composite ceramic and phosphor-in-glass) were developed to avoid the use of resin. However, new challenges emerged: none of them showed sufficient luminous efficacy (i.e., >50 lm/W) and adequate saturation-threshold (i.e., >30 W or 10 W/mm2). Here, we report a facile fabrication of CASN/glass composite films using a simple and efficient blade-coating method. Upon 450 nm excitation, the resultant composite film presents a high internal quantum efficiency of ~83%, comparable to that of pristine CASN powder (~90%). When irradiated with a blue laser, the composite film shows a record high luminous efficacy of 82 lm/W. Furthermore, its saturation threshold was investigated in high power and high power density mode, respectively. When measured in high power mode, it shows a high saturation threshold over 29.7 W (1.75 W/mm2), thus achieving a high luminous flux of 1576 lm; when measured in high power density mode, it shows a saturation threshold of ~10.2 W/mm2 (1.13 W). With abovementioned excellent properties, the CASN/glass composite film has great potential for use in high-power and high color rendering laser lighting.

Transparent ceramics (TCs) with high color rendering index (CRI) are considered as excellent color converters for white light-emitting diode (LED) and laser diode (LD) devices. In this study, by utilizing the component and structural designs between layers, composite structure (Ce,Cr):YAG/Ce:YAG and Cr:YAG/Ce:YAG TCs with high CRI were fabricated by vacuum sintering. Microstructural and luminescence properties, as well as energy transfer from Ce3+ to Cr3+ ions of as-fabricated TCs were explored systematically. Simultaneously, TC based white LEDs/LDs were assembled via the remote excitation mode. Under 460 nm excitation, a high CRI value of 75.2 was realized in (Ce,Cr):YAG/Ce:YAG TC based white LEDs. As increasing the thickness of the Cr:YAG layer in Cr:YAG/Ce:YAG TC, its red emission intensity could be enhanced distinctly. The optimized CRI and CCT values could reach 74.4 and 4146 K, respectively. In addition, the optimized luminous flux (LF) and CRI of Cr:YAG/Ce:YAG TC based LD device were 160.6 lm and 69.1, respectively. Therefore, the composite structure design is an effective approach to realize the essential promotion of CRI value in TC based white LED/LD devices.

In a vehicle, bulbs called the P-group are responsible for warning other drivers or pedestrians and they are known as signal bulbs. Signal bulbs have been used to emit warning and hazard signs in parts such as brake lights, direction indicator, hazard lights (night vision) as well as tail bulbs and car park alarms. There has been limited researches on the photometric characteristics of these lamps, but a review of these studies revealed that no detailed research has yet been done on optimizing these characteristics, and there is a scientific gap. In this study, factors affecting the service life and luminous flux were evaluated by using Taguchi design of experiments method. The results showed that the two factors of weight percent composition of bubble filling neutral gases and the volumetric efficiency of gases injected into the bubble had the most influence on the target parameters. Experimental results showed that the optimum composition of neutral gases injected into the bulb bubble can extend the bulb service life to approximately 341 h, which is three times the service life of a bulb with the inappropriate composition of fill gases. Then the optimum state of the service life and the luminous flux were determined to meet the reference standards. Although the service life and luminous flux parameters were able to reach 341 h and 513 lumens in the maximized state, however, in the optimum state with satisfying reference standards, the service life and luminous flux were 330 h and 463 lumens, respectively. Then, the bulb bubble filling with inert neutral gases and its effect on the bulb service life was investigated. The results showed that if the volumetric efficiency of gas injection increased from the normal 75%–100%, the service life of the test lamps would be improved by about 10%.

The research object of this work is the parameters of organic light-emitting diodes, namely power and luminous flux. Determination of these parameters can be carried out using a photodiode and requires measuring the dark current of the sensor (photodiode), measuring the current of the photodiode when illuminated by the LED under investigation. And also take into account the relationship between the light flux received by the sensor and its output current, and take into account the spectral characteristics of the sensor. Calculate the investigated parameters of the LED based on the measurements. Carrying out these measurements requires laboratory instruments and workplace organization, and further calculations are routine work. It is possible to increase the measurement accuracy by improving the existing methods for measuring the required parameters, and it is possible to automate the process of measurements and calculations using a modern microprocessor radioelement base. Microcontrollers are widespread such radioelements. They have the necessary peripherals for independent operation and have sufficient computing power to implement the required measuring device. Its application makes it possible to automate the measurement process, carry out the necessary calculations, save correction constants, accumulate and process the obtained data, analyze these received data, exchange data with a computer, etc. So, the work is aimed at developing a methodology that will allow the simultaneous measurement of power and luminous flux of planar light sources. And also on the feasibility of this technique in the device and software with the ability to measure the power of the light source in an arbitrary band of the spectral visible range. Thus, it is possible to determine what power in watts a light source emits with the dynamics of supply currents in the optical bands, knowing the spectrum of this source without using glass filters. So, the result of applying the technique is to determine the power of light radiation (in watts) or the luminous flux (in lumens) of the emitter (light sources).

The widespread application of laser diodes (LDs) in high-brightness lighting is limited by the insufficient heat dissipation of colour converters due to high-power laser irradiation. In this study, a novel MgO–YAG:Ce composite ceramic with excellent optical and thermal properties was fabricated by hot pressing. The thermal conductivity of the MgO–YAG:Ce composite ceramic is 14–21% higher than that of the Al2O3–YAG:Ce composite ceramic in the temperature range of 25–200 °C. When pumped by blue LDs with 1 W mm−2, the MgO–40 vol% YAG:Ce composite ceramic produces white light with a luminous efficacy of 292 lm W−1. Moreover, it exhibits a luminous saturation threshold of as high as 32.2 W mm−2 and a maximal luminous flux of 3979 lm. These results indicate that MgO–YAG:Ce composite ceramic is a promising phosphor converter for high-power laser-driven lighting.

Laser-driven white lighting has drawn great attention due to its high-brightness, high efficiency and compact size. However, the current laser lighting usually suffers from a low color rendering (Ra ∼ 60) due to the presence of a wide “Cyan cavity” (460–530 nm) in the luminescence spectrum. Herein, we report on the preparation and characterization of a novel cyan-green color converter, namely Ca3Sc2Si3O12:Ce3+,Na+ phosphor-in-glass (CSS-PiG) film. The addition of Na+ as a charge compensator greatly improved the internal quantum efficiency (IQE) of CSS:Ce3+ phosphors. Because of the good chemical stability and the matching refractive index between the glass matrix and embedded phosphors, the as-prepared CSS-PiG film exhibits an efficient cyan-green emission (with a peak at 508 nm and IQE ∼91%) and excellent thermal stability (maintaining 75% of the room-temperature emission intensity at 300 °C). Under the excitation of a 14.5 W mm−2 blue laser, the PiG film could produce a high-brightness white light with a forward luminous flux of 701 lm, a forward luminous efficacy of 112 lm W−1 and a Ra of 61. By coating a red-emitting CaAlSiN3:Eu2+ layer on the CSS-PiG film, the composite CSS-PiG/CaAlSiN3 film shows an ultra-broadband emission with a full-width at half maximum (FWHM) of 196 nm, which remarkably narrows the “Cyan cavity” and thus provides a Ra above 90. These results demonstrate that the CSS-PiG film is a promising candidate for laser lighting.

Laser diode (LD) driven lighting is expected to be the next-generation lighting, and red CaAlSiN3:Eu2+ (CASN) phosphor is still required for high-quality LD white lighting. Utilizing glass with a suitable thermal expansion coefficient and low softening temperature as the inorganic binder, CASN phosphor-in-glass-films (PiFs) are fabricated in this work. High efficiency and thermal stability are achieved by optimizing the reaction of CASN and glass. Introducing Lu3Al5O12:Ce (LuAG) to offset the luminous spectra of CASN PiFs, broad emission spectra and high efficiency are recorded. High color rendering index (CRI, 88.6), luminous efficiency (LE, 153 lm W−1), and luminous flux (LF, 1162 lm) are achieved simultaneously when the PiFs are excited by a 455 nm blue LD. At last, the high color quality LD white lighting produced by PiFs is displayed for the first time. We believe that the results provided by this work are an enormous progress for PiFs and encourage more researchers to provide new strategies to acquire high performance of PiFs in white LD lighting.

Heat-resistant fluorescent glass is an ideal color converter for laser lighting applications. However, the application requirements of high-quality laser lighting are difficult to meet due to the insufficient availability of cyan, green and red emission components. Therefore, the development of fluorescent green glass with high thermal stability and high brightness is the key core technology in the fields of laser lighting and display projection. In this research, a series of green-emitting (BaSr)2SiO4–PiG samples with high quantum efficiency were successfully prepared by dispersing (BaSr)2SiO4 phosphor in a SiO2–B2O3–CaO–Na2O glass matrix. Meanwhile, the thermal stability, photoluminescence properties, and applicability of (BaSr)2SiO4–PiG in solid-state laser lighting applications have been monitored for the first time. Surprisingly, the thermal conductivity of (BaSr)2SiO4–PiG is 1.87 W m−1 K−1 at room temperature, which is much higher than that of other multicomponent glasses. Furthermore, under 2.69 W mm−2 blue laser incident power density excitation, a maximum luminous flux of 196.7 lm is achieved. More importantly, (BaSr)2SiO4–PiG exhibits an excellent luminous efficiency of 98 lm W−1 at a laser incident power density of 2.09 W mm−2. Based on these investigations, (BaSr)2SiO4–PiG would be a reliable and efficient candidate as a green color converter for laser lighting and displays.

Healing of various ailments using herbal medicines is gaining much interest. Plants classified as grasses, specifically Cynodon dactylon, are an appreciated group of monocots used in many herbal remedies. In this work, C. dactylon, is grown naturally and also under market available LED Luminaires with different lighting conditions. Until 2010, most of the plants are grown under conventional lamps that are not spectrally tunable. Cynodon dactylon, the grass is grown under two different light spectrum, two light levels and three photoperiods (9hours, 12 hours, 15 hours) to extend our experiential knowledge. The biomass accumulation was the highest when grown under a lower RB ratio-12-hour- $163\mu $ mol/s, and phenolic content was the highest at 92.8 mg/g wt Gallic Acid Equivalents under combined light source at 15-hour photoperiod. A spectrally tunable LED light source with an optimal quantity of LEDs saves cost, space and energy. Considering the light parameters from the light sources used for growing C. dactylon, Levenberg–Marquardt (LM) algorithm is implemented to select an optimal LED quantity that composes the light source. The algorithm simulates the given target spectrum with minimum fitness error. The method applied to model LEDs, its validation against the practical LED spectrum, spectrum matching and computation of Luminous flux, Photosynthetic Photon Flux and efficacy are also presented. Many spectrums are simulated to validate the performance of the algorithm. A solution of optimal LEDs for three Photosynthetic Photon Flux (PPF) levels with LEDs is derived, and it is observed that the number of LEDs increased with PPF.

The interrelation between colorimetric (correlated color temperature) and spectral (intensity ratio of spectral emission bands) parameters of white LED lamps for general lighting has been established based on an analysis of test results for a set of lamps during aging. Deconvolution of the lamp radiation spectra is used to show that the change in color temperature is mainly due to a change in the intensity ratio of the 450-nm band originating from the diode heterostructure and the long-wavelength component of the nonelementary yellow band of the phosphor radiation with a maximum at 580 nm. However, the shorter-wavelength component with a maximum of 530 nm manifests itself mainly in the change of the total luminous flux. A possible cause of the change in the intensity of the spectral components of the nonelementary phosphor radiation band may be both thermal effects and structural changes in the phosphor material.

According to DSTU CIE 127:2017, control of characteristics of light-emitting diodes can be carried out in the laboratories of industrial or operational institutions with the use of working standards of radiation sources checked in the certified laboratories. The advantages of mass control of photometric characteristics of radiation sources are the following: higher speed and lower cost at a slightly lower but acceptable accuracy. In order to carry out mass control that meets the above requirements, in terms of production and operation, methods and technical means with a fairly high productivity, low cost of measurements and sufficient accuracy are required. The aim of the work is to solve an urgent problem – to increase the accuracy of measuring the light parameters of LEDs with a concentrated spatial distribution of luminous intensity and luminous flux for photometers without the use of rotating devices. It is shown that a photometer based on standard digital cameras, using a fiber optic focus and a correcting light filter, can provide sufficient accuracy in measuring the spatial distribution of radiation from directional light sources. Due to the use of a focon and matrix discrete photodetectors located in a plane perpendicular to the axial direction of radiation, it is possible to obtain an angular spatial distribution of light source radiation without rotating devices, which in turn reduces the cost of testing. The characteristics and ease of operation of modern digital cameras have allowed their use as a photodetector array, which simplifies the design of the photometer. The error of measuring the characteristics of sources with concentrated types of curves of light using a photometer in comparison with goniophotometric methods does not exceed 5%, which allows the use of such photometers for rapid control of such products in mass production and operating conditions.

The work is devoted to the development of an intelligent lighting control system for adjacent territories.Every day more and more popular is the use of led lamps, they are more economical from outdated gas-discharge lamps or incandescent lamps, which are now commonly used. For comparison, a 40W incandescent lamp has a luminous flux of 400 lumens, the same luminous flux has a 5W led lamp. There are many outdoor lighting network management systems that have a wide range of management capabilities. The most common ones are LonWorks, DMX-512, DALI, DCI. They usually use motion sensors, light sensors, time relays, and other automation elements, each of which has its own advantages and disadvantages. These advantages and disadvantages have been analyzed in terms of application in the system being developed. The main requirements for the system were economic and ease of use. Taking into account these requirements, the existing methods of street lighting management and systems based on them were considered.A block diagram of the lighting control system for the adjacent territories of the enterprise was developed, which is shown in figure Fig. 1. The system is a network whose nodes are connected by a simple digital data bus DB. The digital data bus can be wired, wireless, or optical. Each network node consists of: an MSi motion sensor, an LLi led lamp, a microcontroller with a built-in MCi real-time clock, a light-sensitive LSI sensor, and IUI interface blocks. The light-sensitive sensor can be installed in one place, provided that the level of natural light in the coverage area of each local lighting system is approximately the same. When the level of external natural light decreases below a certain critical level, the light-sensitive sensor sends a signal to the microcontroller to turn on the local lighting system, after which each local zone is illuminated with individual specified parameters of the glow power. When the motion sensor is activated in the local area of the lighting system, the lamp switches to high power mode. Thanks to a real-time microcontroller, the moment when an object appears in this zone is recorded. As the object moves, it enters the coverage area of another local lighting system where the network uses a built-in real-time clock to record the moment when the object appears in another zone, this information is transmitted via a digital bus to the system, from which we can determine the direction of movement of the object.Based on the developed block diagram and based on the requirements for the system being developed, a microcontroller from the STM family was selected. This family of microcontrollers, due to their performance, architecture and low power consumption, is best suited for working with the hardware of the system being developed.

Purpose Optimization of light-emitting diodes’ (LEDs’) design together with long-term reliability is directly correlated with their photometric, electric and thermal characteristics. For a given thermal layout of the LED system, the maximum luminous flux occurs at an optimal electrical input power and can be determined using a photo-electro-thermal (PET) theory. The purpose of this study is to extend the application of the luminous flux equation in PET theory for low-power (LP) LEDs. Design/methodology/approach LP surface-mounted device LEDs were mounted on substrates of different thermal resistances. Three LEDs were attached to substrates which were flame-retardant fiberglass epoxy (FR4) and two aluminum-based metal core printed circuit boards (MCPCBs) with thermal conductivities of about 1.0 W/m.K, 2.0 W/m.K and 5.0 W/m.K, respectively. The conjunction of thermal transient tester and thermal and radiometric characterization of LEDs system was used to measure the thermal and optical parameters of the LEDs at a certain range of input current and temperature. Findings The validation of the extended application of the luminous flux equation was confirmed via a good agreement between the practical and theoretical results. The outcomes show that the optimum luminous flux is 25.51, 31.91 and 37.01 lm for the LEDs on the FR4 and the two MCPCBs, respectively. Accordingly, the stipulated maximum electrical input power in the LED datasheet (0.185 W) is shifted to 0.6284, 0.6963 and 0.8838 W between the three substrates. Originality/value Using a large number of LP LEDs is preferred than high-power (HP) LEDs for the same system power to augment the heat transfer and provide a higher luminous flux. The PET theory equations have been applied to HP LEDs using heatsinks with various thermal resistances. In this work, the PET theory luminous flux equation was extended to be used for Indium Gallium Aluminum Phosphide LP LEDs attached to the substrates with dissimilar thermal resistances.

Problems. Optical distance meters allow measurements of distances to various probing objects. One of the problems is to provide high-resolution, precision and resolution of light-range finders. Therefore, research and improvement of these parameters is relevant.The purpose of the research. Expanding the limits of measuring distances, accuracy and resolution of the light rangefinder.Implementation method. An algorithm for selecting the modulation frequency and its relationship with the quantization frequencies has been developed, which provides a phase relationship between the periods (and in the final state between the phase relationships) of the modulation and quantization frequencies and the selected phase interval. A single quartz oscillator was used to increase the stability of the luminous flux modulation frequency, the reference frequency and the quantization frequencies of the selected information phase interval. The function of structural adjustment of the electronic scale with change of its weight that allows to increase accuracy and resolution of the meter is entered. The possibility of digital signal processing (integration, determination of the average level, mathematical processing and selection of information on the measured distance) to reduce noise effects, increase the stability of signal parameters and accuracy of its measurement. Keywords: modulation light rangefinder, distance, phase-frequency conversion, quantization frequency, measurement accuracy, resolution.Conclusions. The proposed algorithm for choosing the ratio of frequency modulation and quantization frequencies can improve the accuracy and resolution of distance measurement, due to the possibility of changing the quantization frequency and the weight of the electronic scale. The introduction of digital signal processing and the integration of the dedicated phase-frequency range increases the resistance of the meter to the noise effects of the external environment and the configuration of the object of study on the parameters of the light flux.

In this study, we analyze the influence of the pore structure of an SBA-15 particle on the light emission from its inner adsorbed quantum dots (QDs) and outer light-emitting diode (LED) chips. It is found that the particle features of a high refractive index, comparable feature size of pore structure, and lower amount of QD adsorption help with QD light extraction, demonstrating a mechanism to suppress QD light propagating through pores and thus reducing the reabsorption loss. We consequently developed highly efficient QD white LEDs with wet-mixing QD/SBA-15 nanocomposite particles (NPs) by further optimizing the packaging methods and the introduced NP mass ratio. The LEDs demonstrated a record luminous efficacy (the ratio of luminous flux to electrical power) of 206.8 (entrusted test efficiency of 205.8 lm W-1 certificated by China National Accreditation Service) and 137.6 lm W-1 at 20 mA for white LEDs integrating only green QDs and green-red QD color convertors, respectively, with improved operating stability. These results are comparable to conventional phosphor-based white LEDs, which can be a starting point for white LEDs only using QDs as convertors toward commercialization in the near future.

The remote phosphor as a lighting structure has outstanding luminous efficiency compared to other options, such as conformal or in-cup. However, the lack of uniformity in distributed color has prevented remote phosphor from wider development. The answer to the chromatic performance enhancement that has been suggested by numerous researchers is the multi-layer configuration with two or three different types of chromatic phosphor. The research purpose is to select the best configuration for multi-chip white LEDs (WLEDs) to achieve optimal results in color quality scale (CQS), color rendering index (CRI), light output and color homogeneity. WLEDs mentioned in this paper have two distinct color temperatures, 6600 K and 7700 K. Experimental results show that the remote phosphor structure with three phosphor layers is superior in terms of color rendering, chromatic performance, and emitted light. The deviation of correlated color measured in this structure is also low, which means that the color uniformity is greatly enhanced in this multi-layer lighting structure. This result can be demonstrated by analyzing the scattering characteristics of the phosphoric layers using the Mie theory. The research findings have proven the effectiveness of the multi-phosphor configuration and can serve as a guideline to fabricate WLEDs with better performance.

Usually, remote phosphor structures are beneficial in terms of flux but unfavorable in terms of color quality compared to conformal phosphor or in-cup phosphor packages. To eliminate this disadvantage, many studies have focused on increasing the chromatic quality of the remote phosphor configuration, which requires great efforts in improving two parameters of color: color rendering index (CRI) and color quality scale (CQS). CRI is known as the most useful quantitative method used to measure the ability of a light source to reproduce the colors of illuminated objects faithfully and naturally. Similarly, CQS is also a method of lighting quality determination and analysis, especially used as an alternative to the unsaturated CRI colors. In this paper, we proposed dual-layer remote phosphor structure as a novel method of CRI and CQS enhancement to improve WLEDs’ color quality. Five alike WLEDs but having different color temperatures in the range of 5600 K to 8500 K were applied in this study. The idea behind the study is to place a red phosphor layer SrwFxByOz:Eu2+,Sm2+ on the yellow phosphor layer YAG:Ce3+ and then determining an appropriate concentration of SrwFxByOz:Eu2+,Sm2+ added to achieve the highest color quality. The results point out that SrwFxByOz:Eu2+,Sm2+ brings great benefits to the improvement of CRI and CQS parameters. Specifically, the higher the SrwFxByOz:Eu2+,Sm2+ concentration results in the greater CRI and CQS, owning to the enriched red light components in the WLEDs. However, the flux has a tendency of dropping when SrwFxByOz:Eu2+,Sm2+ concentration rises excessively. This has been proved by using the Mie-scattering theory and the Lambert-Beer law. The results of this article are essential references for manufacturing WLEDs with higher chromatic quality.

One of the most common areas of recovered energy based on the direct use of solar radiation is solar energy, namely the use of solar panels. Despite the significant contribution of solar energy to the energy state of the world, the productivity of this method of energy production is low. Improving the efficiency of solar panels by developing and applying an automatic system to increase the light flow on the surface of the panel is an important scientific and practical task.Simulation modeling in the ZEMAX environment is used as research methods.The study of the possibility of using light flow concentrators to increase the productivity of solar panels. The study is based on determining the optimal geometry of cone-shaped concentrators. The possibility of using five special geometries is considered, namely, two variants of "multifaceted prismatic cone", "multifaceted mirror cone" and two variants of "mirror funnels", which with the use of the sun position tracker will increase the productivity of power plants. The study found that the use of "multifaceted mirror cones" is impractical as a concentrator, because when using it, a significant number of rays are refracted in such a way that they move in the opposite direction to the location of the solar panel. When placing the light source at an angle of 90 degrees and using "multifaceted prismatic cones", a significant number of rays remain in the funnel. The use of "mirror funnel" geometry when placing a light source at an angle of 90 degrees determines the best focusing of the rays on the surface of the solar panel. The peculiarity of this geometry is that when the light source is located at an angle of 45 there is no light flux.The proposed geometry of the hub - "mirror funnel" together with the use of the tracker of the position of the light source can be used in the development of an automatic system to increase the luminous flux, and thus increase the productivity of solar installations.

A hybrid surface structure, incorporating an Ag-grid-based aluminum-doped zinc oxide (AZO) transparent conductive layer (TCL), a microhole array, 45°-sawtooth sidewalls, and an SiO2 nanoparticle (NP)/microsphere (MS) passivation layer, is proposed for the characteristic improvement of GaN-based light-emitting diodes (LEDs). In order to optimize the contact behavior between the AZO and p-GaN layers, a 2-D Ag grid is applied on the contact interface. Because series resistance ${R}_{s}$ is reduced by the conductive Ag-grid pattern, a lower forward voltage and a better current spreading ability are obtained. Compared with a conventional GaN LED with an injection current of 200 mA, the proposed device exhibits a forward voltage of 4.01 V, reduced from 4.34 V, and presents 33%, 34.4%, 45.4%, 33.1%, and 45.3% enhancements in the light output power (LOP), luminous flux, luminous efficacy, external quantum efficiency (EQE), and wall-plug efficiency (WPE), respectively. Moreover, a more effective current spreading in the light emission mapping image and a higher intensity in the far-field pattern are achieved. Improvements of both electrical and optical properties verify that the proposed device is promising for practical applications in solid-state lighting.

In this study, the red-emitting phosphor-in-glass (PiG) using the CaAlSiN3: Eu2+ (CASN) phosphor is reported for the first time. The CASN: Eu2+ PiG samples with a maximum luminous flux of 25.1–29.4 for l minute at laser power of 1 W/mm2 was obtained using a low-temperature glass frit and GPS furnace. Despite the increase in the phosphor from 15 to 25 wt%, the PiG produced at low temperature of 380 °C showed robust properties. Finally, the red PiG module designed for rear lamp applications maintains over 90% lumens for a minute at 350 mA and achieves an intense red light having a color temperature of 4589 K.

The article describes a measuring complex based on the 32-bit STM32F103VET6 microcontroller for studying the lux-ampere (light), frequency and inertial characteristics of a photoresistor with different laws of recombination of nonequilibrium charge carriers arising under the influence of light. The developed complex is connected to a personal computer (smartphone) and allows to analyze the rise and fall edges of the photoresistor current, as well as to determine the lifetime of excess charge carriers at different illumination levels. Unlike traditional methods for measuring the parameters of photoresistors operating in a dynamic mode, the proposed measuring complex does not use an oscilloscope and a separate modulator of the luminous flux (generator or light interrupter), this made it possible to significantly reduce the size and cost of the complex, as well as automate the measurement process. To determine the frequency response of the photoresistor, it is proposed to use a frequency synthesizer, which allows, together with a digital-to-analog converter of the microcontroller, to form an amplitude-modulated light flux of the required frequency and modulation depth. The complex described in the work can be connected to the Internet using a Wi-Fi module based on an ESP8266 microcontroller, which allows conducting research in a remote mode. It is also possible to determine the parameters of the photoresistor at different values of the load resistance.

The green InGaN/GaN micro light-emitting diode (Micro-LED) is a significant component in micro-display whereas lack of size dependence and high injected current analysis. In this letter, different size Micro-LEDs were fabricated and the electro-optical characteristics were measured. The size-dependence phenomenon for EQE “efficiency droop”, luminous flux and brightness were observed and discussed. All sizes Micro-LEDs exhibited an extremely high brightness as 37.5k and 67.6k nits at 1 A/cm2, 2.89M and 3.81M nits at 300 A/cm2 for 25 and $200~\mu \text{m}$ respectively. In addition, the elevating current densities from 160 to 6400 A/cm2 were injected into $25~\mu \text{m}$ Micro-LED and the electroluminescence (EL) spectra transformation of different current densities were depicted. The green to blue shift and secondary peak effect, which promise an opportunity to modulate the emission wavelength for higher quality and lower the barrier of mass transfer technology, were observed and analyzed through the spectra.

In this study, an accelerated aging experiment for fabric and paper was conducted using two light emitting diode(LED) sources with different wavelength characteristics, and the discoloration under each lighting type was examined. Hanji(Korean traditional paper) and related textiles showed more discoloration under blue LEDs, while the blue wool standard showed more discoloration under white LEDs. This, indicated that the deterioration varied depending on the sample color. The the effect of the light source on artifact deterioration was primarily related to the total radiation flux(expressed in mill watts), rather than the total luminous flux(expressed in lumens). In addition, the discoloration of the investigated artifacts was dependent on the color rendering of the lighting.

The usage of white LED has increased at a rapid rate in India for residential applications because of its various advantageous properties such as energy efficiency, low power consumption, high brightness, reliability and long lifetime compared to other conventional lamps. In this paper, photometric parameters such as CCT, CRI and luminous flux for warm white and cool white LEDs are explored. Integrating sphere was used for examining the LEDs for their performance characteristics in terms of photometric parameters. The results show that warm white LEDs have a relatively low correlated colour temperature, colour rendering index and luminous flux (lumens) compared to cool white LED bulbs. With an increase in power consumption, the efficacy, lumen output and power factor increase. In terms of high brightness, cool white LED bulbs are brighter than warm white LED bulbs, whereas in terms of power quality issues such as harmonics and power consumption, warm white LEDs are better than cool white LEDs.

In this work, we fabricated a phosphor-in-glass (PiG) film on Al-coated sapphire as reflective color converter driven by a laser diode. The borosilicate glass PiG film was sintered on heat-conducting sapphire and an Al thin layer with high reflectivity was deposited on the other surface of the sapphire, providing the function of heat dissipation and light reflection. The optical performance of the laser-driven white emitter (LD-WE) was adjusted by controlling the PiG film thickness. At a thickness of $120~\mu \text{m}$ , the LD-WE emits white light with a correlated color temperature (CCT) of 6733 K and a chromaticity coordinate of (0.3104, 0.3184). When the laser power increases from 0.32 to 1.12 W, the luminous flux increases from 19.3 to 129 lm and the light quality is stable. The color rendering index (CRI) of LD-WE reaches 82.5 by adding red phosphor. Furthermore, the converter has low working temperature from 30.7 to 45.6°C due to the effective heat transfer of sapphire.

Purpose This paper aims to present the results of investigations that show the influence of soldering process parameters on the optical and thermal parameters of power LEDs. Design/methodology/approach The power LEDs were soldered onto metal core printed circuit board (MCPCB) substrates in different soldering ovens: batch and tunnel types, characterized by different thermal profiles. Three types of solder pastes based on Sn99Ag0.3Cu0.7 with the addition of TiO2 were used. The thermal and optical parameters of the diodes were measured using classical indirect electrical methods. The results of measurements obtained were compared and discussed. Findings It was shown that the type of oven and soldering thermal profile considerably influence the effectiveness of the removal of heat generated in the LEDs tested. This influence is characterized by thermal resistance changes. The differences between the values of this parameter can exceed 20%. This value also depends on the composition of the soldering paste. The differences between the diodes tested can exceed 15%. It was also shown that the luminous flux emitted by the diode depends on the soldering process used. Practical implications The results obtained could be useful for process design engineers for assembling power LEDs for MCPCBs and for designers of solid-state light sources. Originality/value This paper presents the results of investigations into the influence of the soldering profiles and soldering pastes used on the effectiveness of the removal of heat generated in power LEDs. It shows and discusses how the factors mentioned above influence the thermal resistance of the LEDs and optical parameters that characterize the light emitted.

Recent studies revealed that both the Al2O3–Y3Al5O12:Ce (YAG:Ce) composite ceramic (YAG-CC) and single crystalline YAG:Ce (YAG-SC) possess very high luminescence-saturation thresholds (LSTs), which makes them promising for laser lighting applications. The present study is aimed to conduct a comparative investigation between YAG-CC and YAG-SC on aspects of the laser-pumped luminescence and the associated thermal behavior. The colorimetric and photometric properties (e.g. luminous flux/efficacy, correlated color temperature, and color rendering index) were investigated systematically, by conducting the measurements using a custom-built sphere-spectroradiometer system in the transmission mode. It was found that YAG-SC has a superior LST and it could maintain a high luminous efficacy (106 lm/W) under the irradiation of a 15.33 W blue laser, while the YAG-CC saturated at around 7.76 W. Moreover, by combining the thermal imaging data with the spectral variation of the YAG-CC, novel experimental insights into the origin of luminescence saturation were revealed and proposed as the “thermally-induced absorption saturation”.

Due to the global interest of Light Emitting Diode (LED) Technology, LED lamps manufacturers and academic researchers are doing great efforts to study different aspects of LED lamps performance. This paper investigates the photometric and electrical properties of LED lamps. The effect of temperature on the output light emitted from the LED lamps has been studied and a model of LED lamp is simulated and presented in this manuscript. The presented model has been implemented experimentally to investigate the lamp performance. Experimental results show that the effect of aging test on photometric parameters of LED lamp such as luminous flux, correlated color temperature (CCT), color rendering index (Ra). This study enables to understand and well control the features of the visible light emitted from LED lamps. The value of CCT is an important parameter in many applications such as lighting, videography, photography, publishing, horticulture, and manufacturing. It is desirable to achieve a high CRI light in color-critical applications such as neonatal care in hospitals). Experimental results also demonstrate that PF of LED lamp driver decrease when the lamp is operated in high ambient temperature.

A novel optical fiber (OF) embedded building envelope, namely translucent concrete (TC), was proposed and popularized for its light transmission property and unique artistic features, but there is still a lack of in-depth research on its daylighting performance analysis. To reveal the impacts of multi-factors on TC daylighting performance, an optical model of TC was established based on a ray-tracing method. In the model validation, both the simulated transmittance of OFs and illuminance of translucent concrete were in a good agreement with the experimental results. The simulation results showed when the numerical aperture (NA) of the OFs increased from 0.51 to 0.70, the annual average luminous flux of TC under seven cities conditions could be enhanced by up to 40.62%. In terms of effective illuminance, the optimum fiber volume ratio of the seven cities was determined, respectively. Besides, it was found that the core-cladding interface losses could lead to a relative deviation over 5% when the length of 1-mm OFs with 0.51 NA exceeded 259 mm, and the deviation could be larger with the decrease in diameter of OFs and the increase both in length and NA of OFs.

The problem of measuring the parameters of dust particles in the environment is currently relevant for residents of densely populated cities. Measurements of the size and size distribution function of dust particles are carried out using instruments based on the method of scattering of laser radiation. An analysis of the measurement method based on the spherical particle model and the theory of Mie diffraction is performed. The possibility of erroneous indication of measurement results by widely used portable measuring instruments of dust parameters is shown. To calculate the scattering luminous flux by particles with a size of 2–10 μm in laser radiation, a special program was developed in the Matlab medium. As a result of solving a system of linear non-homogeneous algebraic equations, the particle size distribution function is estimated under the condition that the intensity of the scattered laser radiation is measured by at least two fixed scattering angles. For the experimental estimation of this distribution function, four simple photodetectors were used for different fixed scattering angles.

In this article, a ring remote phosphor (RRP) structure comprising an inverted-cone-lens encapsulant and a surrounding phosphor layer was developed and used for laser-driven white lighting. The inverted-cone-lens encapsulant in the structure redirects light from a blue laser diode (LD) to the surrounding phosphor layer, thus preventing intense light from hitting the phosphor layer on a small surface and, therefore, from considerably reducing luminous efficiency. The design of the inverted-cone-lens surface of the encapsulant was investigated, and 3-D ray-trace simulations were performed to confirm its light distributions. The RRP structure with an inverted-cone-lens encapsulant and a surrounding phosphor layer was fabricated to produce laser-driven white lighting, and the optical characteristics of the RRP structure with different phosphor concentrations were examined. The output luminous flux of the RRP samples increased with increased phosphor concentration, whereas the correlated color temperature (CCT) decreased with an increase in phosphor concentration. Therefore, the RRP structure can be used to generate efficiently high-brightness white light.

In visible light communication, it is difficult to control dimming of LED lamp or flicker occurs due to changes in luminous flux according to the data. In this paper, to solve this problem, we proposed a new correction scheme for dimming level in which the dimming level of an LED lamp is corrected in real time by considering the data transmission status. A non-linear correction scheme was applied for red and green LEDs because of the non-linear characteristics of the luminous flux according to the dimming level. Since the blue LED’s luminous flux can be assumed to be linear, a linear correction scheme using two-stage current was applied for blue LED in order to lower the minimum possible dimming level. A downscaled model of the visible light communication system was created to verify the validity of the proposed correction scheme for the dimming level. The luminous flux of red, green, and blue LEDs was also measured according to the dimming level. As a result, the dimming range of 9–100% was obtained regardless of the transmitted data condition. Also, transmitting the data of three sensors through red, green, and blue LEDs and constantly maintaining the entire lighting of the LED lamp are possible by applying the proposed dimming scheme.

A camera-aided method of using high dynamic range photogrammetry was developed to calculate luminous flux radiated to the camera lens from an environment or its subareas, with per-pixel contributions from visible light-emitting sources, objects, and reflective surfaces. A series of equations were derived to calculate the luminous flux with valid sub-divisibility and additivity. A pilot study was first conducted, followed by a laboratory experiment using an integrating sphere to improve and validate this high dynamic range imaging method with a measurement error of 5.6%. This method was then tested in a real office space to estimate ‘visible’ luminous flux arriving at the camera lens simulating a typical view of 30 office users under four different test scenarios (fluorescent vs. LED lighting, with vs. without access to lighting controls). The luminous flux retrieved from each of a total of 120 high dynamic range images was checked with the illuminance measured at the camera lens. This camera-aided method for remote measurement of luminous flux was proven valid and useful for lighting practice and research. Further investigations on this method are necessary to overcome several limitations and issues of the present study.

As implied in the title, the triple-layer remote phosphor (TRP), constructed with the yellow YAG:Ce3+ layer at the bottom, the red CaMgSi2O6:Eu2+,Mn2+ phosphor layer on the top, and the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor layer between these two layers, is suggested in this paper to improve the color and luminescence of white LEDs (WLEDs). In order to control the red light for the purpose of increasing the color rendering index (CRI), it is suggested that the red CaMgSi2O6:Eu2+,Mn2+ phosphor should be applied in the TRP structure. Simultaneously, the structure uses the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor layer to control the green light, which increases the luminous efficacy (LE) of WLEDs. In addition, when the concentration of these two phosphors increases, the yellow YAG:Ce3+ concentration must be reduced to keep the average correlated color temperatures (ACCTs) stable at 6000 K to 8500 K. Besides, appropriate adjusting of CRI, LE, and color quality scale (CQS) is also analyzed by modifying the concentration of the green phosphor and red phosphor. The results show that the CRI can get better values if CaMgSi2O6:Eu2+,Mn2+ concentration is higher. In contrast, the CRI decreases dramatically when the concentration of Ba2Li2Si2O7:Sn2+,Mn2+ increases. Meanwhile, CQS can be significantly increased in the range of 10 % to 14 % CaMgSi2O6:Eu2+,Mn2+, regardless of the concentration of Ba2Li2Si2O7:Sn2+,Mn2+. In particular, along with the improvement of CRI and CQS, LE can also be increased by more than 40 % by reducing the scattered light and adding the green light. Obtained results are a valuable reference for manufacturers for improving WLEDs color and luminescence quality to produce a broader range of WLEDs with better quality fulfilling social needs.

Phosphor-coated light-emitting diode (PC-LED) is the dominant LED technology for public lighting. This paper presents a comprehensive theory for analyzing and modeling phosphor coating (PC) in white LEDs as a dynamic light converter. The new PC-LED model not only obeys the traditional diode equation but also includes the energy storage and transient effects of the PC. Major control variables include energy storage in and the luminous flux from the PC. This new model enables the dynamic variations of luminous flux and energy storage and power loss in PC to be accurately predicted. Part I of this paper provides the details of the theory and analysis leading to the new PC-LED model under the framework of the photo-electro-thermal theory. The details of the model parameter determination, model setup, and experimental verification are included in Part II. The model offers the important power loss equation of the PC which highlights the factors affecting the heat loss and the coating’s blackening effects. This equation can be used by engineers to design LED drivers in order to reduce the coating temperature and the blackening effects and to prolong LED lifetime.