CCTV 3 & 15 exposure LED strobe, these things on the strobe you know?

The development of intelligent lighting is rampant, but the lighting products in addition to dimming, communications and other functions often highlight the highlights of the problem. Stroboscopic will bring health and safety issues, the international standards have been introduced on the strobe, but the focus of different departments of the different focus of attention, evaluation indicators are also very different. This paper makes a brief review of the current international organizations concerned about the stroboscopic evaluation, and proposes an effective means of detection and evaluation.

What is the strobe

Stroboscopic refers to the light flux of a certain frequency. With the phone to the light source can often be found in the distribution of stripes, which is caused by stroboscopic. A certain degree of strobe will not cause attention, there is no physical discomfort; but some strobe is really a problem. In the early 90s, there are a large number of studies have found that migraine, headache, stroboscopic light source and autism, visual fatigue and discomfort is closely related to neurological diseases, serious will make human caused illusion, causing accident. Do not underestimate the stroboscopic, different frequency and the depth of the impact on people is not the same!

1 visible strobe

The human eye is a very complicated system, the individual difference is very large, for the vast majority of people, can be aware of the following 80Hz light flashing, the human eye can perceive the brightness changes, flicker frequency below 80Hz is also known as visible strobe (visible flicker). Visible strobe is ordinary lighting or display unacceptable.

Sensitive weighting function of human eye to strobe

2 strobe effect

For more than 80Hz strobe, the human eye is not easy to find, but it has a greater impact on the perception of the human eye. For example, the moving object is regarded as a series of still images, namely effect (Stroboscopic). As a result of the stroboscopic effect, people may have an illusion, and it is very dangerous to look at some of the equipment that is running fast, even if it is slow.

Stroboscopic effect

Stroboscopic effect of the machine running illusion

3 phantom phenomenon

Similarly, when the light source flicker frequency in 80Hz-2kHz, and in the environment of the object is stationary, the human eye in the mobile position or direction, but there will be still light spot extension system, called the phantom phenomenon, such as car taillights, or scanned outdoor LED display etc..

4 stroboscopic harm

Light source is closely related to many diseases such as migraine, headache, autism, eye fatigue, blurred vision and so on. Research shows that the low-frequency flicker 3-70Hz light source for some people may cause photosensitive epilepsy; for 100Hz frequency were found to be the cause of headache, migraine; for the 120Hz frequency of the flickering light source may affect people's emotions, appear tired and anxiety. The visual illusion caused by the stroboscopic effect and the related mechanical motion is very dangerous in the industrial place. Therefore, it is urgent to solve the problem of the accurate measurement and evaluation of the stroboscopic characteristics of the lighting products.

Two, why LED strobe

LED lighting products with constant voltage DC or AC constant current source driver, light source itself does not produce stroboscopic, stroboscopic depends on the LED drive power because the drive performance of each different strobe LED products are not the same. In particular, some manufacturers in order to save costs, the use of a relatively simple drive circuit, such as AC LED, there will be a larger stroboscopic problem.

As for the intelligent lighting products, dimming is its essential function, and the light is precisely led to another cause strobe. And when the product load dimming function, the strobe will be further exacerbated. Especially in dimming, the greater the depth of its fluctuations, as shown in the following figure. Therefore, the dimming function or claims that it can be connected to the dimming controller lighting products, should be in the light of the dimming and dimming of the measurement of the performance of the stroboscopic light.

Flicker waveform of dimming LED lamps

Three, about the stroboscopic evaluation criteria

At present, there are a number of international standardization of the research team on the issue of stroboscopic launched an in-depth study, and has been or is being issued standards or technical specifications, including the following categories:

1 Energy Star and IEEE

North American Energy Star products certification is the first standard for lighting products made by one of the standard requirements of the strobe, in fact, as early as IESNA lighting handbook in 2000 has put forward the definition and requirements of stroboscopic clear.

The 2015 release of the IEEE file, the stroboscopic risk is divided into several levels, as shown below, the green coverage is not the level of risk, while the yellow area is low risk, more than the yellow part is not acceptable.

Low risk (yellow area) and no awareness level (below green area) schematic

2 California regulations

Put forward different requirements on the stroboscopic measurement and evaluation of the 2015 release of the CEC regulations in California, in section 40Hz, 90Hz, 200Hz wave, 400Hz and 1000Hz, calculation of the modulation percentage, overall is more complex.

3.IEC standard

IEC coverage of the light flicker frequency is 0.05Hz-80Hz. In the standard, a short time flicker value Pst is used to evaluate the visible flicker. In the calculation, the subjective visual perception of illumination is simulated, and the severity of flicker in the period is calculated by calculating the classification probability of instantaneous flicker visual sensitivity