Healthy Lighting

Light the dangers of stroboscopic effect

2011-04-26
  Let us first understand the basic concepts of strobe.

It was found that long to read under fluorescent lights will feel uncomfortable, although its brightness and the day is no different. Why is this? After the study, to realize that this is because the fluorescent light intensity is due to changes over time.
Is due to light flicker.

What is it that strobe light? Strobe light is the light source light speed with time, repeated changes, making the light bounce and instability. Of course the human eye can not be easily perceived light flicker, depending on the frequency of blinking. In general, the less flicker frequency 50Hz, the human eye can perceive light flashes. In 8.8Hz, the human eye is most sensitive. Also, be aware of the maximum flicker frequency (critical flicker frequency) is emitted as light intensity changes, with the light intensity increases critical flicker frequency increases, when the light intensity decreased gradually after the maximum, after critical flicker frequency reduced accordingly. When the light intensity changes greater than the frequency of 50Hz, most people can not tell whether the flashing light, and at this time to a steady light, continuous light, as a reflection of the human eye when the light source is behind changed.
For example, the human eye to detect less than 100 flashes per second (100Hz) of the fluorescent flicker.
Frequency of flashing strobe light effect can be confirmed. Sometimes we find such a phenomenon, when an object move or rotate very fast, they looked as if the actual rate of movement than their slower, even when the rotation frequency of the movement of objects or light flashes with the same frequency (or integer times the relationship), the object seems to stand still. This is frequently the cause of the flash, it is a day we do not want the lighting in the phenomenon.
In fact, the stroboscopic effect, people have a misconception, but some quick running of the equipment is operating as a slow or even still is very dangerous.
There are many light flashes, common are the following:
1, lighting, periodic flashes: If the exchange of fluorescent flicker and voltage fluctuations caused by the flash light source;
2, aperiodic flickering lighting: fluorescent lamps, such as exchange of boot flash, flash all kinds of trouble;
3, the display device flashing: such as televisions, computers, video games, advertising screen, such as scan showed flashes caused;
4, art lights flashing: such as neon, flashing lights and laser, etc..
Why would the strobe light source was?
Flashing light source is essentially a change from the voltage - flux fluctuations - the eye to the human brain in this reaction chain's subjective feelings. Strobe technology produces the mechanism, both the power supply of the factors, but also electric light performance factors, and lighting design unreasonable factors and so on.
The following commonly used light source far as technical performance point of view, the general technical analysis.
(1) low frequency power source. Incandescent lamps, high pressure mercury (sodium) lamps, straight tube (inductive) fluorescent lamps. At this stage, most of the 50Hz frequency sinusoidal alternating current, direct light source to the power supply.
The strobe frequency is 50Hz * 2 = 100Hz, and the law was sine wave.
(2) source voltage fluctuation.
Frequency of AC current, transient voltage fluctuations of 10% to 20%, and significantly increased the frequency of 100Hz, showed a regular fluctuation of the strobe sine wave depth.
(3) electric light performance. Directly heated filament incandescent light for the heat radiation of the light source, light-emitting power, certainly with the frequency of power supply, sine law was volatile. High-pressure mercury (sodium) lamps, straight tube (inductive) fluorescent lamp, although the electrical gas discharge light sources. Start with the ignition but because of its inductive ballasts are used (do not have the AC-DC-AC inverter function). Therefore, the gas discharge light of the discharge power, but also with the inevitable fluctuations in the frequency of power supply fluctuations.
The impact of voltage changes, you can use the visual flicker sensitivity coefficient of the voltage limit curve and the curve of the two concepts to quantify.
Perceived by the human eye can light flashes, can be measured by statistical methods to the human eye on the feeling of light flashing characteristics.
When the flicker frequency 40Hz or more, the feeling is not sensitive; 50Hz flicker to no more than feeling.

Then the strobe on what the human eye will have against it?

Flashing light on the human visual system stimulation, will produce discomfort. The long-flashing light in the work or life, but also may affect the visual system of physical health and mental health. This stimulating effect or influence the severity of light flicker and the intensity, frequency, time, and the continuing role of long-term related. This effect is often slow, so long did not arouse attention. However, with the rapid development of e-people exchanges during the day under fluorescent lights and the monitor screen before the work; at night in the AC and the TV screen under fluorescent light before the life, and even accompanied by the vertigo chaos flooded the art of light, so light flashes on the visual system
impact of increasingly prominent.

In particular, the stroboscopic effect of electric light, to human production, daily life, causing serious health hazards.
Mainly in the following areas:

1, the illusion caused by industrial accidents: the electric light of the strobe frequency, and movement (rotation) of objects velocity (speed) as integer multiples of the relationship. Movement (rotation) motion of objects (rotating) state, it will produce a still, reverse, movement (rotation) speed is slow, and the above error periodically repeated three states vision, cause accidents. For example, the machining industry, Machine Operators, on the forward rotation of the lathe tool, the illusion is reversed.
While for urgent change to the operation, damage to the workpiece, tool, fraudulent claims casualties.
2, hazardous to their health and affect: stroboscopic effect will cause visual fatigue, migraine headaches. Machinery industry in particular, high pressure mercury (sodium) light, and light industry, food, printing, electronics, textiles and other industries, generally a straight tube (inductive) occasions, especially fluorescent lighting. For example, plug-operatives on the assembly line, susceptible to visual fatigue, blurred vision, cause migraines.
Generating positioning difficult situation, the production efficiency is low.
3 hurt young people's eyes, resulting in myopia. In our country 80 years later, straight type (inductive) fluorescent lamps, commonly used in homes, schools, libraries, growing primary and secondary victims of a great, significant vision loss, myopia increased significantly.