In many places, we will see the following method of using a mobile phone to test the lamp’s flicker (refer to the picture below), that is, how to distinguish whether the table lamp has “stroboscopic” phenomenon, everyone seems to have found a universal method to distinguish the quality of the lamp.
However, does the “flicker-free lamp” tested by your mobile phone really have no flicker? When talking about how to choose a lamp, we must first talk about the problem of lamp strobe.
What Is The Strobe?
According to the professional explanation of the entry, strobe is to look at the screen of another electrical appliance on the screen of one electrical appliance. A bright line on the screen of another electrical appliance will move from the bottom of the screen to the top, and then appear from the bottom. In this way, the image is flickering.
This explanation is too academic and professional. Some authors have defined stroboscopically more easily understood: stroboscopic, flickering with frequency, the rapid and repetitive change of light over time is called stroboscopic, and the direct feeling is image jumping , Unstable.
Why Does Light Stroboscopic?
Most light sources have strobes, but the degree is different. LED stroboscopic, to a large extent, is not the problem of the LED chip itself, but from the driving and dimming components. The common causes of stroboscopic are:
- Inferior drive components cannot reduce the “voltage and current output ripples” generated during the process of “from alternating current to direct current “from drive components to LED chips”.
- Poor quality dimming components, or poor compatibility, or use low-frequency PWM dimming.
To What Extent Does The Strobe Affect The Human Body?
Most people can obviously perceive flicker below 50 or 60 Hz. When the frequency reaches a certain level, the human eye will regard the flickering light as a continuous source. This frequency is called the “critical flicker frequency” (CCF).
CCF varies from person to person, and the same person will change under different conditions, but most people’s CCF value does not exceed 100 Hz. Many people feel very uncomfortable when facing stroboscopic frequency below 50/60 Hz, and some people are still uncomfortable between 50-100 Hz.
So how often does it take to eliminate this effect? This varies from person to person, some say 160 Hz, 200 Hz, and some 500 Hz, but the industry basically thinks that there is nothing wrong with reaching kilohertz (KHz).
What Are The Hazards Of Lamp Stroboscopic?
Studies have shown that varying degrees of stroboscopic will affect people’s physiology and psychology. Of course, most of the negative ones, such as damage to eyesight, emotional irritability, and inducing epilepsy. such as:
- For stadiums that need to be illuminated at night, such as billiard halls, table tennis halls, badminton halls, tennis halls, etc., the sports spheres cannot be seen clearly due to flashing lights;
- In the case of photography and video, if using flashing light illumination, it will be unavoidable that dark areas appear during shooting, and black scroll bars appear during shooting;
- The effect of low-fluctuation and high-frequency flicker is not obvious. Migraine or severe headache may occur in a few minutes, often accompanied by symptoms such as nausea and visual disturbance.
- Desk lamp flickering may produce negative effects including strain fatigue, eye fatigue, blurred vision, migraine and decreased vision.
Is There Any Lamps That Do Not Flash?
Absolutely no flicker is actually impossible. The Chinese industry standard requires 3125Hz for qualified products. From a professional point of view, the exact name of “no stroboscopic” is “imperceptible stroboscopic”. According to the “stroboscopic” requirements of the China Quality Certification Center for reading and writing desk lamps, the “fluctuation depth” is a measure of the “stroboscopic” of desk lamps. “The standard value.
Taking desk lamps as an example, the national standard requires that the fluctuation depth of desk lamps is less than 3.2% as qualified. However, it has been proved that many so-called “eye-protection desk lamps” on the market have fluctuation depths of more than 3.2%, which means that most of them are NOT protective-eye.
Is It Reliable To Measure Stroboscopic Frequency On Mobile Phones?
Our answer is: you can refer to it, but it is not scientific!
The current smart phone cameras mostly use COMS photosensitive elements, and the principle of imaging is “sampling + display” at a higher frequency. When the sampling frequency (shutter speed) is greater than the flicker frequency of the lamp, the stroboscopic phenomenon will be captured by the camera.
For example, the sampling frequency of the mobile phone camera is 500Hz (the shutter speed is 1/500s at this time), and the switching frequency of the lamp driving device is 300Hz. At this time, the flicker of the lamp can’t hide from the camera’s capture. And if you manually adjust the camera shutter speed to 1/250s, the camera will not be able to capture the stroboscopic light. At this time, you will think that the light does not flicker.
Nowadays, smart phones automatically adjust the shutter speed according to the scene. In many cases, you cannot detect the flicker through the camera. It is very possible that the “flicker-free” lamps you photographed are garbage with heavy flicker! And the lamps that you photographed with severe flicker are actually within a reasonable range, and the human eye can hardly detect it.
Then how to measure: only use professional stroboscopic detection tools. Of course, we believe that we usually don’t buy an instrument, and just find a lamp to test it.
What Should We Do To Face The Stroboscopic Problem?
It is recommended that end consumers do not buy LED products with no any certificates with low price and low quality, and choose regular brand lamps.
Wholesalers and retailers would better look for manufacturers endorsed by third-party brands and certified by the China Quality Certification Center (CQC). After all, they have been verified by the market and time to ensure the quality of their products. And you can get samples for personal testing, so that you can be more secure.
If possible, you can use a daylight lighting system to introduce outdoor natural light into the room. The natural light is processed by the system, not only without flicker, and will not cause damage to human eyes, but also block most of the ultraviolet and infrared rays, the light is soft, and the illumination is uniform , Warm and comfortable, let us bathe in natural light at ease and return to nature.