Nowadays, smartphone screens are roughly divided into LCD and OLED screens. If users watch one of the screens for a long time, they will cause certain damage to the lens and retina of the human eye, and this damage is usually irreversible!
In general, the main sources of harm are the following two points:
1. Blu-ray
What is blue light?
blue light refers to visible light with a wavelength of 380nm - 495nm. The wavelength generated by the LCD screen is within 447nm, and the wavelength of the OLED screen is within 458nm. That is to say, LCD blue light is a little shorter than OLED blue light. Because the greater the energy at a shorter wavelength, the stronger the penetration, the damage to the eyes of blue light alone, LCD blue light is more harmful to the eyes than OLED blue light.
But in addition to blue light, the factors that affect screen flashing on the human eye cannot be ignored.
2. Screen flash
What is screen flash?
LCD and OLED use different dimming methods, namely DC and PWM screen dimming methods.
DC dimming
In order to enable users to view content on their phone normally under different lighting conditions, the screen needs to change its brightness accordingly. One of the ways to adjust the brightness is called "DC dimming". The principle of
DC dimming is to change the brightness of the screen by increasing or reducing the circuit power. Power = voltage x current, so changing the voltage or current can change the brightness of screen .
PWM dimming
And on the PWM dimming screen, adjusting the brightness does not depend on changing the power, but on the alternation of the screen light and turn off. When the PWM dimming screen is lit, it does not continue to shine, but it keeps lighting up and extinguishing the screen. Because people's eyes have visual stays in painting, when the light and destruction alternate quickly enough, the naked eye will think that the phone is always bright.
Although the flashing rhythm is very fast, the brain can still provide feedback from this phenomenon. Therefore, if you feel this flash for a long time, it will inevitably aggravate the fatigue of the eye muscles, thereby stimulating the refractive system for linkage and accelerating the aging of vision. The higher the flash frequency of
, that is, the higher the screen refresh rate, the smaller the feedback that the eyes need to make. Although there will be screen flashes whether it is DC dimming or PWM dimming, the screen flash frequency of DC dimming is very high, usually above 2000Hz. Currently, the screen flash frequency of OLED mobile phones varies from 120-240Hz.
However, OLED screens are full of colors and realistic, and are already the mainstream of mobile phone screens!
Through the above comparison, we learned that in terms of blue light, LCD screens are larger for eyes, and in terms of screen flash, the opposite is true.
3. Countermeasures
If you want to reduce the harm of the screen to your eyes, you mainly do the following:
1. Avoid looking at the mobile phone screen for a long time;
2. Try not to use it in a dark light environment, because the pupils of people's eyeballs will dilate in dark light environments, which will cause greater damage to blue light;
3. Try not to adjust the screen to a low brightness mode for a long time.
4, wear blue fruit glasses.
5. Use the eye protection mode of your mobile phone.
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