Views: 201 Author: Site Editor Publish Time: 2021-04-29 Origin: Site
In the past, CRT screen will emit radiation. LED has become the mainstream light source of electronic product display screen since 2010, then the problem of radiant light has disappeared. The main problem is whether to be anti blue light or not. Anti blue ray mainly prevents blue light from electronic products. Although there is blue light in the sunlight, the blue light of sunlight does not harm the eyes.
Whether it is statistics or animal experiments (whether it can be applied for experiments), it is pointed out that the blue light of LED is harmful to human eyes. The relevant reasons are as follows.
(1) The blue peak value of LED is much larger than that of other lights(> 60%), which is unlike the blue light of sunlight and its peak value is lower than that of green light.
(2) Combined with photon energy calculation, the blue light energy of LED is 4.5 times higher than that of green light. Unlike the sunlight, the energy of blue light is only 0.9 times of that of green light. Long term exposure to blue light of LED is just like being irradiated by ultraviolet light, so it is necessary to be on our guards.
(3) The LED light of electronic products directly irradiates the human eye, not like sunlight or other light. It is the weak light of the human eye reflected by the object.
(4) The distance between the screen light of the mobile phone, computer and the human eye is only 30 cm, unlike sunlight or other light, which is very far away from the human eye. It should be known that the intensity of light is inversely proportional to the square of the distance. Although the brightness of sunlight and other lighting is far greater than the screen light of mobile phones and computers, the illuminance at this time has been negligible.
So is it necessary to protect against blue light? Of course.
It is unnecessary to bring blue light filter glasses in normal times. But when electronic products are applied, they should be considered to be worn.
In order to achieve better teaching effect, many schools generally adopt touch electronic whiteboard and multimedia interactive teaching machine. Whiteboards applied in many primary schools and kindergartens are getting bigger and bigger, 55 inches, 65 inches, 70 inches or more.
Usually, when children watch TV at home, they will be asked to stay away from them. The reasonable viewing distance of TV is about twice the size of color TV. For example, if it is a 65 inch (165 cm) TV, the best distance to watch is twice that of 65 inches, that is, more than 3.3 meters away from the TV screen. When the 65 inch touch interactive teaching machine is utilized by children, they are only one arm away from the screen, and their eyes are at most 30 cm away from the screen. Theoretically, the illumination of the human eye is inversely proportional to the square of the distance. That is, the distance from 3.3 meters to 0.3 meters is shortened by nearly 11 times, while the energy intensity of the eyes receiving light is increased to 120 times.
When children apply this kind of products, the eyes are constantly damaged by strong light due to the close distance and strong light, which will cause eye fatigue, myopia, retinal damage and so on. This invisible danger often surrounds them. In addition to the interactive all-in-one machines utilized in class, VR products, mobile phones, tablet computers, learning machines and LED advertising screens in shopping malls all drive children to indulge in them. In addition, children have no self-control ability. If there is no restraint, myopia and even more serious injuries are not uncommon. So parents should be extra careful. When electronic products are applied, wera them regardless of age.
In recent years, many anti ultraviolet and anti violet lenses have come to the anti blue light market, claiming to be called transparent blue ray lenses. There are also some adding blue light lenses with a blue luster in the market. Consumers do not understand and buy these invalid lenses, which leads to poor eye adaptation. However, because the practitioners do not know the specifications, they think it is necessary for the consumers to take time to adapt to the lenses, which leads to much questioning.
There are various ways to test anti blue lens in the market. The most common way is to test with a banknote pen or a fake card with a blue light proof test card logo. Consumers do not know and buy these fake and shoddy products, then they will have more distrust of anti blue light products. What is more exaggerated is that blue like purple light is emitted to test the penetration rate, but it directly marks the blue light barrier capacity of 450-490nm in a false way. In fact, as in the above example, marking blue light is not the real test of anti blue light.
If anti blue ray lens for mobile phone and computer are wanted to be bought, the effect should be known on mobile phone and computer. In fact, in the national standard GB/T20145 specifications, the calculation of eye injury function of blue light and blue light eye injury energy are clearly defined. As long as anti blue computer glasses is put on the display screen of mobile phone and the changes of spectrum before and after are measured, multiplied by the blue light eye injury function, the ratio of the reduction of blue light eye injury energy can be calculated. How much effective it will be can be known immediately.
So what is the correct specification? Consumers should buy anti blue light glasses that can reduce the blue light eye damage energy of mobile phones. As for how much blue light eye damage energy should be reduced? It is suggested that about 60% of the total amount should be all right. Such anti blue ray eyeglasses must be effective.