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LED lamps play an important role in daily life, study and work, and are indispensable items. As the most commonly used type of lamps today, LED lamps have the characteristics of no flicker or low flicker rate, which is a crucial assessment indicator. This factor not only affects the visual comfort of users but also directly affects the performance and quality of lamps. Therefore, when choosing LED lamps, we must pay great attention to their flicker performance.
LED stroboscopic/flicker refers to the fluctuation of the luminous flux of an LED light source at a certain frequency. This fluctuation causes the brightness or illumination of the light source to change, thus causing a flickering phenomenon in the human eye.
LED itself is a diode and can only pass direct current, so a power supply must be used to convert AC power into DC power (unless it is battery-powered). The response time of LED's luminous brightness to current is very short, and it changes with the current. How much electricity is passed through, and how much light is emitted, so LED flicker is only related to the frequency and ripple of the output current of its driving power supply.
LED lighting products are driven by AC to DC constant voltage or constant current power supply. The light source itself does not produce flicker. Whether there is a flicker depends on the LED driving power supply. Since the drivers vary greatly, the flicker performance of each LED product is also different.
For smart lighting products, dimming is a necessary function, and dimming is precisely another cause of flicker. When the product is loaded with a dimming function, flicker often intensifies further. Especially when the dimming is dark, the fluctuation depth is relatively large.
According to the different flickering frequencies, the types of flicker can be divided into visible flicker and invisible flicker.
Visible flicker: The human eye can perceive changes in brightness and darkness, and the flicker frequency is usually below 80Hz. This flicker is unacceptable for ordinary lighting or display.
Invisible flicker: The human eye cannot perceive abnormal changes in brightness and darkness, but it can be checked by other equipment. Although this flicker cannot be directly perceived by the human eye, it may still affect vision.
The stroboscopic effect has many effects on the human body, including headaches, eye fatigue, decreased vision, psychological stress, and potential safety issues. In particular, migraine patients are very sensitive to light, and stroboscopic light may induce or aggravate migraines.
In addition, for patients with photosensitive epilepsy, stroboscopic light of a certain frequency (such as 3-70HZ) may trigger epileptic seizures.
Therefore, long-term exposure to stroboscopic light should be avoided as much as possible, especially for those who are sensitive to light and children in the developmental stage of vision.
Using a mobile phone camera can easily detect LED flicker. The specific operation method is as follows:
a. Open the mobile phone camera and point the camera at the LED light.
b. Adjust the shutter speed of the mobile phone camera to the fastest, usually 1/1000 second or faster.
c. Observe the flickering of the LED light in the camera.
If the number of flickers is large, it means the flicker is high;
If the number of flickers is small, it means the flicker is low.
2. Use a professional stroboscope detector
A professional stroboscope detector can detect LED stroboscope more accurately. The specific operation method is as follows:
a. Turn on the stroboscope detector and aim the detector at the LED light.
b. Set the test frequency range and test time of the detector.
c. Start the test and observe the stroboscope data displayed on the detector.
Judge whether the stroboscope of the LED light is appropriate based on the test results.
1. It is recommended not to buy uncertified, low-priced and low-quality LED products, and try to buy regular brand lamps and light sources.
2. A credible product test report must be issued.
LED flicker that is too high or too low can damage human vision. Being in this environment for a long time can easily lead to eye fatigue, dryness, decreased vision and other problems. Therefore, it is very necessary to detect LED flicker.
The shutter speed of a mobile phone camera is very fast and can capture the rapid flickering of LED lights. By observing the number of flickers of the LED light in the camera, you can preliminarily judge whether the flicker of the LED light is appropriate. However, this method is not accurate enough and can only be used as a basis for preliminary judgment.
IEEE P1789 Standard: The IEEE P1789 standard focuses on assessing the flicker of LED lighting products. It provides guidelines for measuring flicker characteristics and setting limits to ensure that flicker does not exceed levels that could potentially cause discomfort or health issues.
IEC 61000-3-3: This International Electrotechnical Commission (IEC) standard addresses the limitation of voltage changes, voltage fluctuations, and flicker in electrical power systems. It sets limits on the permissible flicker levels to ensure the quality of the power supply and prevent adverse effects on connected equipment.
ENERGY STAR: The ENERGY STAR program, overseen by the U.S. Environmental Protection Agency (EPA), has requirements for flicker in LED lighting products to qualify for ENERGY STAR certification. These requirements aim to ensure that certified products meet specific criteria for flicker performance.
CIE S 026: The International Commission on Illumination (CIE) has published CIE S 026, which provides recommendations for the lighting of workspaces and outdoor work areas. This document includes guidance on flicker perception thresholds and aims to minimize flicker in lighting installations.
National Regulations: Different countries may have their regulations and standards related to flicker in LED lighting. These regulations often aim to protect consumers from potential health risks associated with flickering lights.
