How to reduce the risk of light strobe?

Last Update Time: 2019-07-03 10:40:05

l  Stroboscopic hazard

1. Photosensitive epilepsy or scintillation-induced epilepsy:

Existing research data and industry experts point out that photosensitive epilepsy does exist. Bittencourt and Fisher proposed the epidemiology of photosensitive epilepsy in 2004 and 2005. Bittencourt pointed out that photosensitive epilepsy has a low incidence rate in the whole population, with an annual incidence rate of about 0.001%, and an incidence rate of about 0.006% among adolescents. And the probability of suffering from this disease in patients with epilepsy is as high as 10%.


Fisher estimates the incidence of photosensitive epilepsy in people aged 5 to 24 by measuring abnormal brain waves of light stimulation. The incidence rate is between 0.01% and 0.025% in people aged 5 to 24 years, and 2% to 14% in patients with epilepsy under the stimulation of flashing light sources. The chance of inducing rapid epileptic seizures. The American Epilepsy Work Foundation pointed out that the factors influencing the symptoms of photosensitive epilepsy include scintillation frequency, light intensity, modulation depth, spectral composition and some factors related to the visual nervous system.


2. The persistence effect of stimuli caused by stroboscopic

Bullough et al. used a series of waveforms and frequencies to study the stroboscopic effect of a solid-state light source and found that the drive modulation depth, frequency, duty cycle, and waveform have an impact on the visibility of the stroboscopic effect.

At the same time, industry experts also agree that the stroboscopic effect is mainly caused by a series of problems caused by visual artifacts. SafetyatWork mentioned that although some lights are not visible to the human eye, they will rotate in the field of view. The machine appears to be visually slow or static, which is very dangerous and can easily cause accidents.


3. Physiological problems such as headache, migraine, nausea, and visual disturbances

The American Headache Society points out that many people with migraine headaches are more sensitive to light, especially glare, bright light sources with flicker can cause migraine, and low-frequency flicker is more severe than high-frequency flicker; some flashing fluorescent lights or TV screens can cause migraine-like Symptoms, many studies have also shown that for these scintillation-induced migraine patients, their EEG is usually different from those without migraine. However, the physical discomfort caused by those factors of the scintillation source has not yet reached a definitive conclusion.


4. Use eye fatigue, vision loss

The flashing of the lighting fixtures often affects human productivity. When studying the effect of flicker on people's fatigue level, it is found that the mental fatigue caused by flicker is very small, and the main factor causing human fatigue is the work content; non-visible flicker can affect the movement trajectory of the eyeball, affecting reading and causing vision loss. Studies by Wilkins et al. have shown that visual correlation performance at higher frequency scintillation sources is better than low frequency sources.


l  Strobe determination criteria

The relationship between the flash frequency and the fluctuation depth function of low risk and imperceptible levels of influence


The document pair stroboscopic criteria are:

(1) The frequency is lower than 9 Hz, and the undetectable fluctuation depth limit is 0.288%;

(2) The frequency is in the range of 9-3120 Hz, and the undetectable fluctuation depth limit is: frequency × 0.032%;

(3) The frequency is greater than 3120 Hz, and it is considered that there is no stroboscopic at all, and the assessment is exempted.


l  How to reduce stroboscopic

Analysis of the cause of stroboscopic, it can be found that the key to reduce stroboscopic is electric light source technology and drive technology. If the LED is driven by a constant, non-oscillating DC source, the stroboscopic effect can be achieved. Drivers in the market also need to consider driving costs, size, reliability, efficiency and other factors, manufacturers and industry experts also try to find a strobe level that people can accept.



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