Valonvälkkyminen

Valonvälkkyminen, known in English as light flicker, refers to the perceived rapid fluctuation in brightness of a light source. This phenomenon is often associated with artificial lighting, particularly older types of fluorescent lamps and some modern LED and discharge lamps that are not properly designed or driven. The human eye can perceive flicker if it occurs within a certain frequency range, typically between 10 and 100 Hz. At higher frequencies, flicker may not be consciously detected but can still have subtle physiological and psychological effects, sometimes leading to discomfort, headaches, or eyestrain.

The cause of light flicker is usually related to the power supply to the light source. For alternating current (AC) powered lights, the current and voltage fluctuate, which can cause the light output to vary. In incandescent bulbs, this effect is minimal due to the thermal inertia of the filament. However, in fluorescent and discharge lamps, the light output is directly tied to the electrical discharge, making them more susceptible. Modern LED lights can also flicker if their drivers do not provide a stable, direct current.

The perception of flicker is subjective and depends on the frequency, amplitude, and waveform of the fluctuation, as well as individual sensitivity. While some flicker is unavoidable, excessive or noticeable flicker is generally considered undesirable in lighting applications, especially in workplaces or environments where tasks requiring visual acuity are performed. Regulations and standards exist in many countries to limit flicker levels in artificial lighting to ensure visual comfort and performance.