LED lamps have become a popular choice for lighting solutions due to their energy-saving and environmental benefits. However, one major issue with LED lamps is their tendency to flicker, which can have negative effects on people’s health and well-being. In this article, we will explore the basics of LED light flickering, how to identify it, and its potential harm.
What is LED light flicker?
In the standard sense, flicker is the appearance of a bright line moving from the bottom of the screen to the top, and then reappearing from the bottom. In layman’s terms, it is the rapid and repeated change of light over time. The essence of the stroboscopic light source of LED lamps is the fluctuation of luminous flux, which is driven by AC or pulsed DC. The luminous flux, illuminance, or brightness changes correspondingly with the periodic change of the current amplitude, causing a flickering effect.
How to Test for Flickering and Strobing in LED Lights？
The strobe of LED lights is generally invisible to the naked eye, and professional methods require special instruments to see its spectrum. The most direct and convenient way to judge whether the LED light is blinking is to use a mobile phone to take pictures or videos of the lit LED light.
Flicker below 50 or 60 Hz is not noticeably perceived by most people, and above a certain frequency the human eye perceives flickering light as a continuous light source. This frequency is called the “critical flicker frequency” (CFF), and it varies from person to person and under different conditions. For most people, light flicker below 80Hz can be detected, this is called visible flicker, which is unacceptable for general lighting or displays.
Causes of LED light flickering
The flickering of LED lamps is a phenomenon that is commonly observed in many light sources. However, the degree of flicker varies across different sources. It is important to note that the LED chip itself is not usually the primary cause of flicker in LED lamps. Instead, flicker is mainly attributed to the LED drive power supply and dimmer.
One common cause of flicker is an inferior LED driver. This type of driver is unable to reduce the voltage and current output ripple generated during the AC to DC conversion process. This leads to significant power supply ripple, which can be highly inappropriate. Light sources lacking appropriate electronic circuits, such as ballasts, drivers, or power supplies, tend to produce stroboscopic effects. The degree of fluctuation in the output luminous flux determines the severity of the stroboscopic effect.
Another factor that contributes to flicker is an inferior dimmer. This type of dimmer has poor compatibility or uses low-frequency PWM dimming. Dimming is a crucial function for smart lighting products such as smart downlights. However, it is also another cause of stroboscopic effects. When lighting products are loaded with dimming features, flicker tends to worsen. This effect is particularly pronounced when the dimming is set to a lower level, as the depth of fluctuation is relatively higher. As a result, lighting products that have a dimming function or are connected to a dimming controller should be evaluated for their stroboscopic performance under both maximum and minimum dimming settings.
What is the harm of stroboscopic LED lamps?
Studies have shown that different degrees of stroboscopic flicker will affect people’s physiology and psychology. Of course, most of them are negative, such as damage to eyesight, irritability, and induction of epilepsy. for example:
1. For sports venues that need lighting at night, such as billiard halls, table tennis halls, badminton halls, tennis halls, etc., the sports spheres cannot be seen clearly due to the flickering lights;
2. In the case of photography and videography, if the lighting with flicker is used, it will be unavoidable to avoid dark areas and black scroll bars during photography;
3. Including strain fatigue, eye strain, blurred vision, migraine headaches, and decreased vision; 4. The effect of low-fluctuation and high-frequency flickering is not obvious, and migraine or severe headache may occur within a few minutes, often accompanied by symptoms such as nausea and visual disturbances.
How to Prevent LED Lamp Flickering?
Avoid Extremely Low Brightness Settings
When selecting dimming LED lamps, it is common to assume that a high-power LED lamp can always be dimmed down to a suitable level. However, this approach does not account for the fact that current LED dimming methods typically rely on PWM (pulse-width modulation) dimming, which switches the LED on and off to achieve the desired dimming effect. This means that the higher the brightness, the higher the flashing frequency, which is less harmful to people.
Therefore, during the lighting design phase, it is advisable to avoid using high-power lamps for low-brightness scenes such as movie viewing, and instead use low-power lamps such as wall lamps for ambient lighting. This approach reduces the need for dimming and minimizes the stroboscopic effect.
Choose a High-Quality LED Driver
Top 12 LED Driver Manufacturer
Tridonic drivers and similar devices use reliable rectifier components and high-quality driver chips that can reduce output ripple, which significantly improves the stroboscopic performance. For integrated lamps and lanterns, the manufacturer can make specific requirements for the driver’s quality.
LED lighting products are powered by constant voltage or constant current power supplies that convert AC to DC. The strobe performance of each LED product differs due to the various types of drivers available. Some unscrupulous manufacturers use simple drive circuits, such as AC LEDs, to cut costs, which results in significant stroboscopic issues.
Opt for Digital Dimming
Analog dimming methods such as phase-cut dimming require high compatibility between drivers and dimmers and are prone to signal interference during transmission. Digital dimming methods offer many more options for compatibility.
Conclusion
LED lights have become increasingly popular in recent years, but they can suffer from flickering, which can be harmful to human health. Flickering can occur due to a number of reasons, including the use of inferior LED drivers, poor-quality dimmers, and incorrect dimming methods. To avoid flickering in LED lights, it is important to choose high-quality LED drivers, use digital dimming methods, and avoid turning down the brightness of dimming lamps to very low levels.
At Lacelesty Lighting, we are experts in LED lighting and can help you choose the right products and avoid common problems like flickering. Contact us today to learn more about our LED lighting solutions and how we can help you achieve the perfect lighting for your needs.
