By Terry Clark, Chairman and Chief Technology Officer at Finelite
The goal of this white paper is help you understand the possible effects of flicker on customers and how the type of LED Power Supply used can affect the level of flicker produced by LED luminaires.
Why Does Flicker Matter?
When flicker is perceived by the average observer it can be interpreted simply as annoying and/or distracting. For at-risk observers, such as those sensitive to light, individuals with Autism, and those with photosensitive epilepsy, especially children, flicker under certain conditions may trigger health issues within these populations which include migraines, eyestrain, seizures, and impaired visual performance.
The presence of flicker in LED lighting applications is dependent on the light modulation characteristics of the LED Power Supply, the ambient light conditions, the sensitivity of the individuals using the space, and the tasks performed.
The U.S. Department of Energy (DOE) defines flicker as a “variation of light output over time,” and states that “all light sources flicker to some degree.”
Flicker and LED Power Supplies
There are two types of LED Power Supplies to choose from when specifying LED lighting systems. It is important to understand the technology underlying each type and how it effects the amount of flicker generated in a space.
Pulse Width Modulation (PWM) LED Power
Supplies dim the light by rapidly switching the current on and off to the LEDs. The ratio of time on to time off determines the perceived brightness of the LED. PWM LED Power Supplies may not exhibit objectionable flicker when current is at 100%, but when dimmed, flicker may become apparent.
Constant Current Reduction (CCR) LED Power
Supplies dim the light by reducing the amount of current delivered to the LED. The LED does not turn on and off. CCR LED Power Supplies may exhibit a ripple on the output current signal.
Download the Flicker White Paper to learn more.