At the on-site trial session of the 3.15 party last year, the host introduced an easy way for consumers to verify the quality of the LED lamp: align the lamp light source with the camera of the mobile phone. If the viewfinder shows fluctuating stripes, the light bulb is present. "Strobe" problem. It is understood that this kind of invisible strobe phenomenon directly affects the health of the human body. When the eyes are exposed to the strobe light environment caused by poor quality lamps for a long time, it can easily cause headaches and eye fatigue.
The strobe of the light source essentially refers to the frequency and periodic variation of the light emitted by the light source over time between different brightnesses and colors. The principle of the experiment is that the shutter time of the mobile phone is faster than the 24 frames/second continuous dynamic flash that can be recognized by the human eye, so the strobe phenomenon that cannot be recognized by the naked eye can be collected.
Strobe has different degrees of health impact. The American Epilepsy Work Foundation pointed out that the factors that influence the induction of photosensitive epilepsy symptoms mainly include the flicker frequency, light intensity, and modulation depth. Fisher et al. in a study of the epidemiological theory of photosensitive epilepsy pointed out that patients with epilepsy have a 2% to 14% chance of stimulating epileptic symptoms under the stimulation of scintillating light sources. The American Headache Society stated that many people with migraine headaches are more sensitive to light, especially glare, bright light with flicker can cause migraines, and low-frequency flicker is more serious than high-frequency flicker. While studying the effects of flicker on people's fatigue, experts found that non-visible flicker can affect the trajectory of eyeballs, affect reading and lead to vision loss.
Light is the only light source available at night indoors. In everyday home use, the impact of the flash light source on people, especially the elderly and children, is obvious. Whether studying in the library, reading, or resting in the bedroom, inappropriate light sources not only reduce efficiency, but long-term use may also leave health risks.
Examine the technical mechanism that produces strobe, there are the factors of the power supply, the technical performance of the electric light source and lighting design and other factors. For many lighting fixtures, the operating current of the light source fluctuates with fluctuations in the input voltage, which directly leads to fluctuations in the output of the light, which in turn causes strobing. Based on cost considerations, many merchants' products on the market do not use chips with constant current functions, but choose ordinary chips that are half of the cost, making the quality performance of lighting products uneven, causing consumers to choose to trouble.
Compared to the simple test, IEEE published "Draft Risk Assessment-Potential health effects of flicker from LED lighting" (IEEEPAR1789:2013) in April 2013, and proposed a more professional criteria for stroboscopic flash. The document states that when the frequency is lower than 9Hz, the undetectable fluctuation depth limit is 0.288%; when the frequency is in the range of 9-3120Hz, the undetectable fluctuation depth limit is the frequency *0.032%; and when the frequency is greater than 3120Hz At the time, it can be considered that there is no strobe at all.
Analyzing the causes of strobe light, we can see that the key to reducing strobe light from the product level is electric light source technology and drive technology. The driver products on the market need to consider factors such as driving cost, size, reliability, and efficiency. Manufacturers and industry experts are trying to find a strobe that people can accept.