As the mobile Internet spread, more and more people began to stare at screens almost all day (except when they were sleeping) - if you're not looking at your computer screen at work, you're looking at your phone screen at rest. At the same time, the harm of blue light on the human eyes is more and more obvious and serious (the main symptoms are: eye fatigue, eye dry, eye tears, eye sting). The most effective and direct way to reduce the blue light damage is to reduce the amount of blue light emitted from screen. As a result, there are all kinds of eye protection apps on computers and mobile phones.

Nowadays, many display devices are added the "automatic brightness adjustment" function, which can reduce the eye harm from screen light to a certain extent. But this is far from enough, because more eye injury caused by display is from slant cold blue spectrum. It is one of the main inducements that cause human cerebral cortex to become overexcited and unconsciously stay up too late, even result in sleep disorder or insomnia