For a long time, people have been arguing about whether OLED screen or LCD screen is more harmful. According to the current development pattern of the industry, the popularity of OLED screen is a major trend. After all, even Apple iPhone also uses OLED screen.
OLED screen is known as “hot eye screen” and “tear screen”, but is OLED screen more eye-damaging than LCD screen? Let’s have a brief discussion.
What is blue light?
Whether it is LCD screen, or OLED screen, will emit blue light.
The Blu ray here is not the Blu ray HD in the video, but refers to the visible light with the wavelength of 380nm – 495nm, which will cause certain damage to the lens and retina of human eyes.
The wavelength of LCD screen is within 447nm, while that of OLED screen is within 458nm, which means that LCD blue light is shorter than OLED blue light.
The shorter the wavelength, the greater the energy and the stronger the penetrability. In theory, LCD blue light is more harmful than OLED blue light.
When it comes to this, some people will be surprised. It is said that OLED screen is more eye-catching. How can LCD screen be more eye-catching in theory? The reason is very simple, there is another factor that has an impact on the human eye, that is screen flash.
What is screen flash?
LCD and OLED adopt different dimming methods, namely DC and PWM.
In order to let the user watch the content on the mobile phone under different light conditions, the screen needs to change the brightness accordingly. One way to adjust brightness is called “DC dimming”.
The principle of DC dimming is very simple, that is to change the brightness of the screen by increasing or decreasing the power of the circuit. Power = voltage x current, so changing the voltage or current can change the brightness of the screen.
On the PWM dimming screen, the brightness adjustment does not depend on the change of power, but on the alternation of on and off of the screen. When the PWM dimming screen is on, it doesn’t keep on lighting, but keeps on lighting and turning off the screen. When it turns on and off fast enough, the naked eye will think that the mobile phone is always on.
Although the rhythm of flash is very fast, the brain can still make feedback from this phenomenon, so if you feel this flash for a long time, it will inevitably aggravate the muscle fatigue on both sides of the eyes, so as to stimulate the refractive system to interact and accelerate the aging of vision.
Whether DC dimming or PWM dimming, there will be screen flicker, but the frequency of DC dimming is very high, usually above 2000Hz, while the frequency of OLED mobile phone screen flicker is only 240Hz.
Therefore, through the above content, we can understand that the LCD screen with DC dimming has a very high flash frequency, which is completely within the healthy range; The flash frequency of OLED screen with PWM dimming is much lower than 1250hz, which will cause certain discomfort to human head.
As a matter of fact, it’s basically clear which one is more harmful to the eyes, OLED screen or LCD screen. Although the two screens use different light technologies, they can cause damage to the eyes. If PWM dimming is the main culprit of OLED screen damage, then the LCD screen with DC dimming also has an irreversible impact on vision, because you can’t ignore the harm of blue light.
In order to reduce the harm of mobile devices to eyes, we should mainly do the following:
1. Try to avoid looking at the screen for a long time;
2. LCD screen should not be used in dark light environment as far as possible, because people’s eyeball pupil will enlarge in dark light environment, which will cause more damage to blue light;
3. OLED screen should not be set to low brightness mode for long time.
If you want to really solve the problem of cell phone screen eye injury, the best way is to watch less and use less cell phone.