I. Overview
1. The basic concept of flashing
It has been found that reading books under fluorescent light for a long time will be uncomfortable, although the brightness is the same as during the day. Why is this? After research, it turned out that this is because the light intensity of the fluorescent lamp changes with time. That is, the flashing of the light source.
So what is the light source flashing? The flashing of the light source is a rapid and repeated change of the light emitted by the light source over time, making the light source jump and unstable. Of course, the human eye does not easily perceive the flicker of the light source, which depends mainly on the frequency of the flicker. Generally, at a blinking frequency of 50 Hz or less, the human eye can perceive the flicker of the light source. At 8.8 Hz, the human eye is the most sensitive. At the same time, the maximum flicker frequency (critical flicker frequency) that can be perceived changes with the intensity of the light emitted by the light source. As the light intensity increases, the critical flicker frequency also increases. When the light intensity reaches a maximum, it gradually decreases. The critical flicker frequency is also reduced accordingly. When the light intensity changes at a frequency greater than 50 Hz, most people can't tell if the light source is flashing. At this time, the light source emits a steady, continuous light, because the reflection of the human eye can no longer keep up with the change of the light source. It is. For example, the human eye does not notice the flicker of a fluorescent lamp of 100 blinks per second (100 Hz).
Light source flicker can be confirmed by the stroboscopic effect. Sometimes we find a phenomenon in which when an object moves or rotates very quickly, they appear to move more slowly than they actually do, even when the object moves or rotates at the same frequency as the source (or an integer) When the relationship is doubled, the object seems to be stationary. This is the reason for the stroboscopic light, which is a phenomenon that we do not want to happen in everyday lighting. In fact, people have the illusion of stroboscopic effects, and it is very dangerous to think of some fast-moving devices as slow or even stationary.
There are many kinds of flashing lights, and the following are common:
1. Periodic flashing of illumination: such as stroboscopic flashing of AC fluorescent lamps and flickering of light source due to fluctuations in power supply voltage;
2. Illumination non-periodic flashing: If the AC fluorescent lamp starts to flash, various faults flash;
3. Display device flicker: such as flashing caused by scanning display of TV, computer, electronic game machine, advertising screen, etc.
4, art light flashes: such as neon lights, lights and lasers flashing.
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