Fudan University teamed up with Philips to solve the problem of LED glare

In recent years, with the rapid development of LED light sources in road lighting applications, LED street lights have attracted more and more attention to the problem of uncomfortable glare caused by drivers and pedestrians. In many areas, nighttime drivers repeatedly experience nighttime vision loss caused by sudden changes in streetlight brightness, reducing the driving safety benefits provided by streetlights, especially the widespread installation of new and popular energy-efficient LED streetlights seems to make things worse.

A group of researchers from China and the Netherlands have developed a method to assess the impact of uncomfortable glare on LED roads, creating a model that can assess driver discomfort levels under various lighting conditions. Team researchers are from Fudan University, Philips Asia Research Institute (Shanghai, China), Human Technology Interaction Group, Eindhoven University of Technology and Philips Research Laboratory (Eindhoven, The Netherlands).

Uncomfortable glare is notoriously difficult to characterize. The glare study conducted by Fudan University in Shanghai and Eindhoven University of Technology in China focuses on finding the key factors that cause discomfort and glare, which leads to the need for humans to face the light source. The research team set up a lab to simulate street lighting work scenarios, allowing volunteers to observe 72 different lighting conditions. Lin Yandan, an associate professor at Fudan University, said: "With the development of the LED industry, there is no doubt that more and more LED lights will be used for road lighting. We believe that there is an urgent need in the lighting industry to update the illuminance of LED road lights caused by characterization. the way."

Conventional LED street lights less, more blue <br> <br> Lin Yandan said evaluating discomfort glare traditional criteria and based on the nature or manner of traditional light sources, LED lamps may not be suitable, for example, with the same brightness of LED Smaller than traditional street lights, this may increase discomfort glare. In addition, the blue portion of a typical white LED spectrum is more energy-intensive, which may also result in more glare because, according to previous studies, the blue light of the human eye is brighter under the same brightness.

In the survey, the team designed a lab setup that mimics the road lighting conditions under different conditions. The researchers blacked out the floor and walls of a room and placed different light sources around the room to mimic the lighting of LED street lights on dark roads. The researchers adjusted the light source to create 72 different lighting conditions, volunteer observers. It is required to define the level of discomfort glare. There are nine rating scales in the table, from “unremarkable” to “unbearable”.

The test also has some benchmarks for previous glare test research, Lin Yandan said: "Although the characteristics of traditional light source uncomfortable glare may not be applicable to LED lights, the factors affecting comfort glare may remain unchanged." The researcher system has been modified. Experimental four-point lighting parameters: brightness of LED lighting, background brightness, the size of the LED light from the perspective of the observer, the angle of the LED and the observer's line of sight.

From the results of the laboratory validation of road lighting <br> <br> Based on these results, the research team developed a model, they used two additional experiments confirmed that the model - in a laboratory, in a On the real road. The researchers found that the interaction between the brightness and solid angle of the LED is the most significant factor affecting comfort glare. To minimize uncomfortable visual experience, they recommend reducing the amount of light that hits the eye and the contrast between the streetlight and the background. These can be achieved by a good LED lighting unit optical design and careful placement of the brightness contrast between the individual lights.

The project will continue to follow up, hoping to guide industry standards, and researchers hope their models will be used by LED street lighting designers and construction companies. Looking ahead, the team plans to interdisciplinary studies of physiological changes caused by glare, such as eye movements and pupil size studies, to deepen the measurement of the glare 9-week measurement.

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