Secret LED strobe: How to determine the quality of LED lights?
Last year 3.15 evening scene test link, the moderator for consumers introduced a verification of the quality of LED light simple way: with mobile phone camera to the light bulb, if the viewfinder appears to fluctuate stripes, it shows that there is a "stroboscopic" problem.
It is understood that this visually difficult to discern the phenomenon of stroboscopic direct impact on the health of the human body, when the eyes long-term exposure to poor lighting caused by the stroboscopic environment, easy to trigger headaches, eye fatigue and a series of problems. Light source Stroboscopic, in essence, refers to the light emitted by the light with time in different brightness, color between the frequency and the period of change.
The principle of the test is that the shutter time of the mobile phone is faster than the human eye can recognize the continuous dynamic flashing 24 frames/second, so can be collected to the naked eye unrecognized stroboscopic phenomenon. Strobe has a different effect on health. American Epilepsy Work Foundation pointed out that the impact of photosensitive epilepsy symptoms induced by the main factors include flicker frequency, light intensity, modulation depth and so on. Fisher and other people in the study of photosensitive epilepsy epidemic theory, epilepsy patients in the flashing light source stimulated by 2% to 14% of the probability of inducing rapid epilepsy symptoms. The American Headache Society says many migraine sufferers are more sensitive to light, especially glare, flashing bright light sources can cause migraines, and low-frequency flashes are more severe than high-frequency flashes.
In the study of the impact of flicker on people's fatigue, experts found that invisible flicker can affect the trajectory of the eye, affect reading and lead to decreased eyesight. Light is the only light available at night in the room. In the daily household use, the frequency flash source to people especially the old person, the child and so on crowd's influence is obvious.
Whether in the study, reading, or in the bedroom rest, unsuitable light source not only reduce efficiency, long-term use may also leave a hidden danger to health. The technical mechanism of generating stroboscopic is studied, including the factors of power supply, the technical performance of electric light source and illumination design. For many lighting fixtures, the operating current of the light source fluctuates with the input voltage fluctuation, which directly results in the output fluctuation of the light, and then produces the stroboscopic.
Based on cost considerations, many of the market's products do not use a constant-current function of the chip, and the choice of cheap half of the common chip, making the quality of lighting products uneven performance, resulting in the choice of consumers troubled. Compared with the Simple Experiment, IEEE published in April 2013 "Draft Risk assessment-potential Health effects of flicker from LED lighting" (ieeepar1789:2013), This paper puts forward a more professional judgment standard for stroboscopic.
The paper points out that when the frequency is lower than 9Hz, the imperceptible fluctuation depth limit is 0.288%, and when the frequency is in the 9-3120hz range, the imperceptible fluctuation depth limit is the frequency *0.032%, and when the frequency is greater than 3120Hz, it can be considered completely without stroboscopic. Analyzing the causes of stroboscopic, it can be found that the key to lighten the frequency flicker from the product level lies in the technology of electric light source and driving technology. The driving cost, size, reliability, efficiency and other factors in the market should be considered. Manufacturers and industry experts are trying to find a level of stroboscopic that people can accept.