When parents choose eye protection light for their children, they often think that the brighter the light is, the better the light is. This reminds me of the story that in the 1990s, we thought that the whiter the flour is, the better the LED light is. Now everyone knows that the whiter the flour is because of the addition of whitening agent, which is harmful to people. Therefore, to judge whether a thing is good or bad, we must know its internal structure.
Here I will talk about the basic knowledge of light source. Eye protection light is because the high-frequency rectifier circuit makes people not feel the flicker of fluorescence. This is the technology of Philips in the 1980s, and now all large and small manufacturers can do it. The key to the eye protection effect lies in the color rendering of the light and the color temperature of the light. The eye protection light uses fluorescent tubes. At present, the main light-emitting materials used are:,
- Pure tricolor powder,
- Brine powder,
- A mixture of the two.
According to the cost accounting, the eye protection light whose retail price is less than 100 yuan can not be called eye protection light basically, because it is not a pure three primary color eye protection light which is actually harmful to the eyes, so it can’t talk about the effect of eye protection. (the price of pure tricolor powder is nearly 10 times that of halogen powder) no analysis is made here, but only the color temperature of pure tricolor powder light tube is discussed here.
The light of the tricolor tube is the light that can emit the red, green and blue tricolor light sensitive to the human eye. The phosphor yttrium oxide (emitting red light, with a peak wavelength of 611nm), magnesium aluminate (emitting green light, with a peak wavelength of 541nm) and barium magnesium aluminate (emitting blue light, with a peak wavelength of 450nm) are mixed into tricolor phosphor in a certain proportion, so as to emit a light closer to the sun light. Color temperature is the feeling of the human eye to the illuminant or white reflector. Generally, from 10 noon to 2 pm, in a clear and cloudless sky, the standard sunlight is about 5000-5500k without direct sunlight, but the light at this time is the most poisonous and dazzling. (see the white light near the bluish part below).
LED lights and lamps
Today’s energy-saving lights generally use 5500-6500k color temperature, eye protection lights generally use 4500-5500k color temperature, many of our consumers feel eye pain after reading under the table light, the reason is that the color temperature and color rendering of the table light are not suitable for close reading. It’s easy to compare the same book under different color temperature lights. The higher the color temperature, the whiter the light is, the more dazzling the written reflection light is. The lower the color temperature, the warmer the light is. The softer the written reflection light is, and the less irritating the eyes are. We can see from the experiment that the effect of reading is the best when the color temperature is about 4000K, and there is basically no reflected glare. And why only a few manufacturers use 4000K color temperature light? There are only two reasons: first, the higher the color temperature of the light, the cheaper it is; second, the higher the color temperature, the brighter the light looks, just like the flour added with whitening agent, the better it sells!
Therefore, remind the users of desk light and eye protection light that the brighter the light is, the better the light is. The light for reading and learning is soft, and the standard color temperature between 3800-4200k is the most suitable.