In addition to various “exciting” breaking news, each year CCTV will also periodically send some simple trucks to identify counterfeit and malicious products, such as this year’s
Where does the “strobe” come from?
Due to the problem that the desk lamp is connected to AC power instead of DC power, the fluorescent lamp will turn on and off during use, and will become “strobe” – this lamp is on and off, and the lights are on. Is. Electricity). Generally, people with eyes less than 100 Hz can feel the eyes easily. The eyes at 100 ~ 500 Hz may not feel it, but it affects the visual nerve of a human. After 500 Hz, it does not affect. Flashing above 500 Hz, the normal use of the lamp does not matter, of course, the better, the higher the cost.
So if you can see the flicker of a table lamp with your bare eyes, don’t buy it … but there is no bulb anymore, and some eye-saving lamps with stroboscopic lights above 100 Hz or the human eye. Can’t reach Strobe, phone CMOS should be out. Use a real-time electronic viewfinder from a mobile phone or camera to target the light source so that the light source occupies at least 2/3 of the viewfinder area. If you observe that the light source in the viewfinder is unstable (striped or change light and shadow).
Why can the phone strobe “shoot”?
Currently, the CMOS imaging process for smartphones comes from progressive scanning imaging. This is the root cause of the jelly effect and strobe effect that a mobile phone will carry. The CMOS sampling frequency (shutter speed) is higher than the switching frequency of the lamp and you will see a strobe. For example, the light bulb is intended for the viewfinder frequency 500Hz (shutter speed 1 / 500s) of a mobile phone camera, and the frequency of switching power to the lamp is 300Hz. At that point, you’ll see the strobe.
And you know, under the condition that the mobile phone’s camera is directly exposed to the light source, the shutter speed will automatically adjust quickly. Will not be able to
As Huawei P9 Plus is used, I would like to give you an extreme case to explain this problem. Usually, such a test method, the camera pointing the lamp to the camera phone first Its fast shutter speed can be made, so the frequency is not enough. Some lower-level bulbs will naturally be drawn with lines. If your lamps are powerful enough, you can manually shutter the Huawei P9 Plus. speed can try to adjust the speed of 1/4000. I believe that the high frequency of any lamp cannot be more than that. now …
The strobe has become an important indicator for testing the quality of light sources or lamps. Several groups, both internally and abroad, have conducted deep research on the topic of a strobe. At present, the International Electrotechnical Commission (IEC), the Institute of Electrical and Electronics Engineers (IEEE), the European Union Directive, the US Energy Star, etc., and China’s CQC regulations have adopted relevant lamps. The requirements for the strobe are presented next. Commonly used indicators are Flickr Index (FI), Flicker Percent (PF), Modulation Depth (MD), and so on. In general, the higher the FI, the more flicker the flicker is, and the closer it is to the flicker frequency.
Therefore, using the smartphone method can only measure one aspect of the strobing problem, which can help us save some low and low-quality lamps. For more users, who need a higher level. And distinguish the strobe difference of high-level lamps, we need to refer to the professional testing equipment.