Investigation On High-quality,Healthy,Intelligent Lightings Based On Light-emitting Diodes

The semiconductor lighting industry in China has been undergoing an unprecedented revolution in technologies,creating abundant opportunities.Technology breakthrough is far more than expected,the industry leading edge extends rapidly,and trans-boundary lighting and innovative applications have become long-term growth momentums.The semiconductor lighting has ushered in a new era of trans-boundary cooperation.China’s semiconductor lighting industry is in a critical period driven by three impetuses,namely the light quality improvement based on biological mechanism research and health needs,the digitalization based on LED(Light-Emitting Diode)controllability,and the extension of innovative applications different from general lighting.These three impetuses promote the integration between semiconductor lighting and the new generation of information technology,and propel the development of lighting and innovation applications.With the development of LED lighting and its control technology,people begin to pursue excellent optical quality instead of high photosynthetic efficiency.LED light source is compact,easy to control and adjustable,providing opportunities and challenges for providing lighting with healthy light quality.With the expanding of application requirements,it holds important significance in upgrading LED light quality and providing healthy and comfortable lighting environment by optimizing LED lighting and its control system and using them reasonability in light environment design of indoor and outdoor.In this paper,a solution is introduced to design the quadruple-color-LED-based light source,which has taken into account both non-visual effects and traditional properties of visible light.At its core lies an algorithm named optical power ratio algorithm that functions as a liaison between desired Spectral Power Distributions(SPDs)and Pulse-Width-Modulation(PWM)duty cycles.With this solution,we can obtain proper light emissions with finely tailored SPDs that comfort both eyes and bodies for high-quality lighting for both indoor and outdoor.1.For indoor lighting,this article mainly discusses three typical lighting applications,including the product-showcase lighting,the office lighting at night,and the bedroom lighting at night.Principles of fine visual and non-visual parameters diversify with applications of spaces.Although these cases all prefer high color rendering index(CRI)for correct color rendering,their requirements for correlated-color temperature(CCT)and circadian action factor(CAF)differ.The product-showcase lighting requires maximum CRI but no specific CAF;the office-at-night lighting needs maximum CAF for better work incentive and CRI ≥ 80;and the bedroom-at-night lighting demands minimum CAF for relax at home and CRI ≥ 80.For these three lighting scenarios,we use the optical power ratio algorithm to achieve corresponding PWM currents of each combination to drive individual LEDs and measure parameters,exhibiting satisfactory agreements between measured and set values,and demonstrating high accuracies and practicalities of the optical power ratio algorithm.Finally,we achieve an LED light source which can perfectly meet the requirement of the high-quality and healthy lighting.2.Outdoor light sources must guarantee excellent mesopic luminance(Lmes)for traffic safety at night.Here,we propose a solution to improve mesopic-related parameters,which include especially the scotopic/photopic ratio and the Lmes,of multi-chip LED light sources.Generally,these sources are driven by PWM currents,and possess readily-controlled SPDs.An updated version of the optical power ratio algorithm developed in this article can select suitable overall SPDs and yield corresponding duty cycles to drive individual chips at different CCT and operating temperatures.Its accuracy and practicality are proven by experimental results.In addition,our study introduces a temperature-feedback technique that can instantly adjust duty cycles for each chip according to real-time operating temperatures in order to avoid undesirable color drifts at different operating temperatures.It can also be regarded as a model for practitioners who desire to improve the quality of outdoor light sources.