What Makes LED Light Flicker and How to Avoid It

Nowadays, most conventional light sources are phased out due to climate change, which makes LED fixtures becoming more and more popular and widely used. We all know that LED fixture is one of the optimal options for illumination, but there is still a problem with a flicker of LED fixture. Actually, most light sources are annoying with a certain extent of flicker. If you use the integrated camera of your smartphone to take a picture of the fixture, you will find there are striations on the picture. Though the appearance of striations is also affected by the specification of the camera and smartphone, it is one of the simplest ways to verify flicker. It is said that flicker is harmful to human health, so we should pay attention to avoid the flicker. This post would like to talk about what makes LED light flicker and how to avoid it.

What is Flicker

Illuminating Engineering Society of North America (IESNA) defined the flicker as a ‘variation of luminance in time’. Flicker is the flutter and unsteady lighting for the human visual sense. The fluctuations of voltage supply modulate the lighting output, and then a flicker appears. Lighting intensity also changes rapidly when flicker occurs. The flicker higher than 80Hz is not easy to be perceived by human visual sense, creating an illusion the rotating and moving objects are static. This phenomenon is called the stroboscopic effect. The stroboscopic effect is hazardous to workers who operate the machines in an industrial environment. The motion of the machine will be slower or even stopped due to the stroboscopic effect, workers can’t perceive the danger of operating the machine and touching it, which may result in injury.

There are two types of flicker: visible and invisible flicker. Visible flicker can be perceived and observed by humans. Invisible flicker is not perceivable but will still do harm to human health. Generally speaking, the flicker lower than 50 Hz is perceivable by most humans, but some people may not perceive till 100 Hz. Nevertheless, visible or invisible flickers would cause problems in health and well-being. It is known that the light flicker between 3Hz to 55Hz can cause various photosensitive epileptic seizures. Many also suffer from migraines and eye stains as they are more sensitive to flicker in higher frequencies. Other defects include reduced visual performance, distraction, less motivation, headaches, dizziness, impaired intellectual, etc. The severity impacts of flicker depend on the exposure time, fluctuation wavelength, and individual pathology. However, studies show that a frequency higher than 2 KHz or a low-frequency flicker without amplitude will not have harmful effects on human health.

What makes LED light flicker

 As mentioned before, flicker is defined as the ‘variation of luminance in time’. Variation of luminance can be achieved by changing the current flowing through the LEDs. In other words, when you dimmed LED fixtures, the power supply is adjusted. Dimming LED fixtures do not function through LEDs but through the whole lighting system. LED lighting systems mainly consist of LEDs, drivers, and electronics (such as power supply and LED load). LEDs are not the source of flicker, but the driver and electronics. As a result, Flicker is related to driver, connection, and dimmer.

Bad LED driver

LEDs are not connected to the power directly. Therefore, an LED driver is a gadget that is typically designed to supply electrical current for LEDs. Since LEDs need to be driven in DC-current, the driver converts the AC-current to DC-current for LEDs. There are constant voltage LED drivers and constant current drivers. The constant voltage driver ensures the constant load of voltage for each LED, but the current is changed with the load. The constant current driver provides the original current for LEDs. This type of driver is ideal for supplying current for LEDs. A bad driver will cause a flicker as it can’t normalize and stabilize the output to LEDs.

Loose connection

Loose connections of wiring and lighting fixtures can cause flicker. It is not difficult to understand that the loose connection of wiring will cause intermittent current supply through the LEDs, resulting in flicker. Loose connection of lighting fixture includes the problem of the connection point of the lighting fixture or at the panel. When you turn on or off the lighting fixture, the current cannot be fully intact through LEDs, and then flicker presents.

Dimmer incompatibility

Dimming is the major cause of flicker. LEDs are more complicated to dim as they are not connected to power directly but are based on electronics for the current supply. The dimmer switches the lighting fixture through the power going on or off at different frequencies (several times per second). However, the mechanism doesn’t work well on LEDs. There are two major dimming methods: Pulse Width Modulation(PWM) and Constant Current Reduction(CCR). PWM switches LEDs at a constantly high frequency. It works perfectly at low levels but is still possible to cause flicker in high frequency. CCR switches LEDs by reducing the electric current. CCR is free of flicker but it is not suitable for deep dimming levels.

How to avoid LED flicker

An LED system is composed of a dimmer, driver, and LED fixtures. The dimmer and driver are critical for reducing flicker. Flicker can be minimized in constant and free-variation current supply. Manufacturers are trying to minimize flicker without increasing the cost and reducing reliability and efficiency. They also make efforts to optimize the lighting product with acceptable flicker for different applications. But in fact, end-users find it difficult to deal with flicker but avoid it. The following steps may help you to avoid LED flicker.

Choose the right driver

The right driver helps in eliminating flicker and get a better lighting effect. Dimming is controlled by the driver. Objectionable flicker can be avoided by choosing the right driver with the right dimming method. Driver with PWM dimming methods may introduce flicker in high frequency. Driver with CCR dimming methods will not create undesired flicker but it is poor at deep dimming levels. Right drivers reduce the risk of hazardous health impacts related to flicker.

Ensure the stable connection & power supply

Loose connections of wiring and lighting fixtures can cause flicker. A stable connection refrains from intermittent current supply through the LEDs. A stable power supply is important as the voltage may fluctuate when LED fixtures and other appliances work at the same time. The insufficient voltage supply causes undesirable flicker. Check the connection of the wiring and the lighting fixture itself if the lighting fixture is flickering. For example, check whether the plug and socket are connected well. If the problem still persists, you may need to consult an electrician for further disposal.

Choose LED fixtures from credible manufacturers

The simplest method to avoid flicker is choosing LED fixtures from credible manufacturers. Credible manufacturers do not only concentrate on the lighting fixtures' quality but also on the user's health. In contrast with the simple assembly of the lighting fixture, credible manufacturers put in more effort to ensure the premium quality of lighting fixtures by doing several tests before selling them. They also care about the user's health, aiming to minimize harmful effects like glare and flicker. Moreover, credible manufacturers are guaranteed with relative certifications.

AGC is aimed to provide high-quality and efficient LED lighting solutions for consumers. Free and professional lighting design, strict quality testing, and long-term warranty are all provided. For more info, feel free to contact us.