Now when it comes to buying a desk lamp, the first question everyone cares about is: Is there a strobe?

Due to the improvement of the quality of life, people have paid attention to the damage caused by the stroboscopic light source to the eyes. But is strobe the only important indicator for desk lamps?

Strobe, as the name suggests, is a flicker that occurs due to frequency. The phenomenon of light source stroboscopic means that the light emitted by the light source changes rapidly and repeatedly with time, which makes the light source beating and unstable.

This kind of jumping and instability is divided into visible flicker and invisible flicker according to the human body. Generally speaking, humans can perceive light flicker below 50Hz, and some people will not notice it until 100Hz. In recent years, scientific research has found that low-frequency flicker of about 3-70Hz may cause epileptic seizures in high-sensitivity people.

Although flickering is not felt by the human eye when the frequency is greater than 100Hz, moderate flickering between 100-500Hz may lead to indirect perception of stroboscopic effects, such as continuous tension in the eye muscles (although the human brain does not Active awareness), causing headaches, eye fatigue and physical and mental fatigue, so people are paying more and more attention to the stroboscopic of electric light sources.

So is there a completely flicker-free electric light source?

Have. But neither.

Don't be surprised, because nothing is absolute. Especially in complex daily environment. To put it simply: if it is absolute direct current, then the mainstream electric light sources on the market can be completely flicker-free. But this kind of absolute direct current environment hardly exists in people's daily life.

Our country's electricity is 50Hz alternating current, and this 50Hz frequency will cause the stroboscopic flicker of the electric light source. Even incandescent lamps (halogen lamps) have strobes in the AC environment, just because incandescent lamps (halogen lamps) have thermal inertia, and when the power is cut off until the next time the power is turned on, there is still residual heat on the filament to emit light. It's like turning off the power when I was a child, but the filament in the light bulb still glows at that moment. That's the truth. As long as the AC power supply is stable, the frequency of 50Hz is not enough for incandescent lamps (halogen lamps) to appear stroboscopic that human perception can perceive.

So when it comes to table lamps, many people will first recommend incandescent lamps, thinking that this kind of light bulb is cheap and has no stroboscopic, and it is the most suitable electric light source. But the problem is: incandescent lamps have been completely phased out all over the world, and the supply of goods cannot be guaranteed. In addition, incandescent lamps have a high loss rate and short lifespan. If they are broken during use, they will not be able to buy light bulbs.

As an advanced product of incandescent lamps, halogen lamps are the selling point of many desk lamps. But halogen lamps waste energy, consume electricity (negligible for children), and the small amount of ultraviolet (UV) and infrared (IR) radiation inherent in the product needs to be considered.in addition, due to the bulb structure of halogen lamps, there are natural weaknesses in lighting height, amplitude, etc., so just comparing stroboscopic light is considered the best light source for reading and learning, which is not scientific.

The light-emitting principle of fluorescent lamps (CFL lamps) and LED lamps is different from that of incandescent lamps (halogen lamps). Sometimes it even produces stroboscopic flicker that can be felt by the naked eye, which is very uncomfortable.

How to solve it?

The most perfect solution is to abandon alternating current and switch to direct current. But this is almost difficult to do, because in addition to table lamps, there are ceiling lamps, wall lamps, spotlights... Not many people will go to great lengths to change all the lighting sources in their homes to direct current.

How do we solve this problem?

Fluorescent lamps that used magnetic ballasts in the 1990s faced complaints about strobes, and manufacturers solved the problem by switching from magnetic ballasts to electronic ballasts. Because the frequency of electronic ballasts driving lamps exceeds 20,000 Hz, which is far beyond the frequency that the human body can detect, basically the CFL lamps using electronic ballasts can ignore stroboscopic.

However, things are not always perfect: the driving circuit of this high-frequency lamp will have an electromagnetic signal of 30-50kHz. If the electronic components are not up to standard and the quality is low, although the effect of "flicker-free" (here means that the human body cannot detect the stroboscopic, the same below) can be achieved, it may affect the body due to radiation and other reasons. After all, the lamp used for reading and learning is placed on the table, very close to the child, and there is no obstruction. As for other lighting sources in the home, due to the distance, it will not have such an impact as the desk lamp.

As for LED lights, from the light-emitting theory, LED lights themselves will not produce stroboscopic, and whether there is stroboscopic or not depends on the LED drive circuit. Due to the wide variety of drivers, the strobe performance of each LED product is also different. In particular, some manufacturers use relatively simple driver chips in order to save costs, and there will be a large stroboscopic problem.

In addition, many LED lights use PCB boards with lamp beads soldered, which has high requirements on the driving power supply. Any minor errors such as hardware quality problems may cause dead beads, stroboscopic, and uneven light color. , or even no light at all.

If the power supply and other electronic components are of poor quality, the radiation caused by them may also have adverse effects on the body. Therefore, LED lights are typical of "very plump in theory and very skinny in implementation", and truly "you get what you pay for".

To sum up, after rummaging through various materials, I found that whether it is incandescent lamps, halogen lamps, CFL lamps or LED lamps, in practical applications, as long as the quality of the lamps passes the standard (in line with industry standards, there is a national standard quality certification), The AC power supply system is stable and can achieve "no stroboscopic". Therefore, the "eye protection lamp" that uses "no stroboscopic" as the biggest selling point on the market is more of a gimmick to follow the trend of public attention, especially those that do not have all important indicators such as color temperature and color rendering. But only mentioned the so-called "flicker-free" so-called eye protection lamp. This is also the reason why when I first shared the experience of buying eye protection lamps, I took the stroboscopic problem directly.

Regarding the strobe, it is necessary to add another explanation: the most popular method on the Internet, "using a mobile phone to illuminate the light to determine whether there is a strobe", is not absolutely scientific, because the strobe seen in many cases is just the beat frequency - beat frequency When two waves with similar frequencies are superimposed, they will produce a frequency equal to the difference between the two original frequencies. This new frequency is called the beat frequency.

To put it simply, because mobile phones are not specially made for stroboscopic testing, each mobile phone manufacturer uses different camera sampling rates and image processing programs, and testing strobes has certain sampling rate and bandwidth requirements for equipment. Using a mobile phone to look at lamps and lanterns will show different effects on the screen at different distances and different angles. It is said that the detection of the mobile phone lens as close as possible to the light source will be more accurate. In addition, changing the shooting mode to manual, or using a fixed-speed camera, there will be no strobe with distance. But I haven't tried either of these methods.

There is also a method that I have not practiced but is said to be correct, is to point the fan at the light source. If there is strobe, look at the light source through the fan, the gap and black line in the fan will be more obvious; if there is no strobe, the fan will see the light source. It will be smooth, smooth, and gapless. Interested mothers can try it.

It is worth reminding again: in the case of meeting the "flicker-free" requirement, the most important thing to pay attention to is the quality of the supporting power supply, electronic components, etc., because this involves the radiation and service life of the lamps. But this, unless it is an industry insider, it is difficult for ordinary consumers to understand in depth. I also did not find industry standards for accessories, circuits, etc., which is a pity. Therefore, in these aspects, we can only continue the simple and simple principle of "you get what you pay for", and try to meet all the conditions in the qualified products of regular manufacturers and within the acceptable price range (some other indicators are also listed below) After that, try to find a higher price.

The above is some of my learning experience about the strobe lamp. But in fact, as the light source for reading and learning that is closest to the child and has been used for the longest time, the important indicators are:

Color temperature

Illumination

Apparent value

Glare

And lighting height, amplitude

Back to the title of this article - is a desk lamp that does not flicker a good desk lamp?

Answer: No. Only a table lamp that meets all the above indicators is a good table lamp.