Phone screens have undergone changes in screen size again and again, from monochrome displays to today's 6.0-inch displays, from LCD to OLED screens. More and more of our time is occupied by this small screen. Mobile phones have become the world's most important personal devices. The impact of smart phones on human health has also become the focus of many people's attention. AMOLED is circulating on the Internet, so is AMOLED really hurting the eyes more than LCD screens?
AMOLED screen really hurts the eyes more than LCD screen?
PWM low frequency dimming becomes the original sin
As we all know, AMOLED screen is a screen made of self-luminous organic material. It does not need LCD backlight. When current passes through organic material, pixels will emit light by themselves. Therefore, compared with LCD screen, AMOLED has more Pure black and higher contrast display advantages.
However, being more "ideal" also means paying more. The "sad eye" of AMOLED displays stems from external dissatisfaction with the current widespread adoption of PWM low-frequency dimming by AMOLED manufacturers. Here is a brief explanation of the PWM low frequency dimming technology.
All displays have a brightness adjustment function, but due to the difference in materials, the dimming technology is different. The current mainstream brightness adjustment technologies for smart phones are DC dimming and PWM dimming.
LCD screens rely on LED backlight panels to emit light. Therefore, in the field of smart phones, LCD screens mostly use DC dimming. This is a technology that directly adjusts the brightness of the two sides of the light-emitting component to adjust the brightness. The smaller the current, the lower the brightness.
DC dimming is relatively straightforward, but there is also a big disadvantage. Because the three primary colors have different wavelengths, DC dimming can cause unavoidable color casts under extremely low brightness conditions, such as early LCD screens that used DC dimming. , At low brightness, there will be obvious problems of discoloration.
The DC dimming does not seem to be suitable for AMOLED screens. AMOLED screen is a technology that relies on organic materials to emit light. Its display quality has a great relationship with the material, and the color difference between pixels will be very obvious.
Under DC dimming, the early Galaxy S, S2, Note and other models will have uneven white and serious color cast problems.
In fact, even though this problem has not been solved well until now, maybe it is the case that PWM dimming has become another option and has entered everyone's sight.
Unlike DC dimming, which directly adjusts the current to control brightness, PWM dimming is more clever. Everyone knows that switching the light source will cause flicker. The faster the switching speed, the faster the flicker. When the frequency of switching the light source exceeds the limit of the human eye, the brightness of all pictures is superimposed in the human eye, so the frequency will affect the brightness of the screen. This technique is called PWM dimming (pulse width modulation).
The introduction of PWM dimming solves the problem of low-brightness color cast in the early days of AMOLED displays, and in fact further improves the color stability.
However, using PWM dimming, even if the human eye cannot sense the picture change during the switching process, we will respond to this phenomenon. It is more likely to cause fatigue on the muscles on both sides of the eyes, thereby stimulating the refraction system to accelerate the vision. Ageing.
At present, Samsung ’s AMOLED screens use 250Hz low-frequency PWM dimming technology. When the screen brightness is lower, the possibility that the human eye can perceive becomes larger, and it is more likely to affect sensitive people.
AMOLED screen hurts the eyes? In fact, LCD screens are not spared
AMOLED displays that use PWM low-frequency dimming for a long time do seem to affect vision, but do n’t think that LCD can be spared. Even with DC dimming, it also has an irreversible effect on vision-cannot be ignored Blu-ray hazard.
Different from the AMOLED self-emission mode, the LCD screen uses a combination of backlight and filter imaging. In mainstream technology, many LCD screens will use blue LED backlight panels, which are covered with red, green and colorless three. This kind of filter forms three primary colors of RGB when blue light passes through these three filters.
Among them, the short-wave blue light emitted by the blue backlight plate can cause harm to human eyes. Because short-wave light has a greater capacity density and is more penetrating, it will directly penetrate the lens to the retina, causing atrophy or death of retinal pigment epithelium cells.
The technology itself is error-free, the use habits have a greater impact
From a technical point of view, whether it is an LCD or an AMOLED screen, the impact on vision is universal. As far as smartphones are concerned, it cannot be said that AMOLED screens are more eye-damaging than LCD screens.
Even if the LCD party held high the banner that PWM low-frequency dimming is harmful, it could not fully prove that AMOLED screens have an impact on vision, because everyone's habits of using mobile phones are different, and the impact on everyone is different. There is no doubt that in the end, it is still the usage habits that need attention. For example, users should try to avoid watching the mobile phone screen for a long time; reduce the low-brightness viewing time of LCD and AMOLED in the dark environment and so on.