Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers
|Publication Date:||26 March 2015|
The scope of this recommended practices document is to
- Define the concept of modulation frequencies for light-emitting diodes (LEDs) and discuss their applications to LED lighting.
- Describe LED lighting applications in which modulation frequencies pose possible health risks to users.
- Discuss the dimming of LEDs by modulating the frequency of driving currents/voltage.
- Present recommendations for modulation frequencies (flicker) for LED lighting and dimming applications to help protect against known potential adverse health effects.
Presently, there are no standards on safe modulating frequencies for high-brightness LEDs. Vendors suggest various driving frequencies-some at low frequencies and others at high frequencies. In the late 1980s and early 1990s, studies showed that office fluorescent lighting with magnetic ballasts modulating at twice the ac line frequency increased the incidence of health-related problems, such as headaches, eyestrain, and, when the lamps were in failure, epileptic seizures. The detrimental effects depend on factors such as brightness, angle of viewing, wavelength, and depth of modulation, among others. The purpose of this document is to describe some possible health risks associated with low-frequency modulation of high-brightness LEDs and provide recommended practices to aid the design of LED driving systems to modulate at benign frequencies in order to help protect against the described health risks.