OLED to every home
In modern flagship smartphones and devices of the mid-price category, manufacturers most often install OLED matrices. The reasons for using such displays instead of other matrices, for example, IPS, are many – a more contrasting picture, higher brightness, energy efficiency. OLEDs also offer deeper blacks thanks to OLEDs. Unused pixels and those that need to display black are disabled. This saves battery consumption and allows you to implement the Always on Display function, thanks to which the user can see important notifications and the clock even when the screen is off.
IPS is a technology in which liquid crystals used to transfer images are arranged parallel to the panel. There is a layer under the crystals that illuminates them. Thus, the backlight illuminates the entire plane of the matrix, while in OLED each diode glows independently. IPS is much cheaper and more durable, but in many of the above qualities it is inferior to OLED, which explains the popularity of the latter.
The first Apple smartphone to feature an OLED display was the 2017 iPhone X. Apple called the screens based on this technology Super Retina and later used them in both the iPhone Xs and Xs Max. In the iPhone 11, the company divided smartphones into regular versions with IPS displays and Pro versions, which received slightly improved features and updated Super Retina XDR matrices. Since 2020, all iPhone models use Super Retina XDR.
All Samsung flagships in the Galaxy S and Note line from the very first model are equipped with AMOLED displays, which are one of the varieties of OLED. Recently, many companies have begun to install various types of OLED-matrix in mid-budget smartphones, such as Samsung Galaxy A32, Redmi Note 10, Honor 30i or Realme 8.
Impact on health
In addition to the advantages described above, such matrices also have a number of disadvantages, including burnout and pulse width modulation, or PWM.
Pulse width modulation (PWM) is one of the ways to regulate the brightness of OLED displays, which is usually considered one of the simplest and most economical, but it has a serious drawback – flicker, which many users, bloggers and gadget reviewers say, can cause severe eye strain and headaches.
Natalia Bosha, an ophthalmologist at the European Medical Center, confirmed to ! that when the user decreases the brightness level of OLED displays, the flicker decreases. The low flicker rate of the OLED display causes multiple contraction and dilation of the pupils, which can cause eye fatigue, nausea and headache. High frequencies at maximum screen brightness do not affect the eye so much due to the flicker flicker threshold of the human eye – this function of the eye allows you to perceive light that flickers at a high enough frequency, as if it were constantly on.
“With less flickering, which happens with a significant decrease in the brightness of the screen, as well as the proximity of the screen to the eyes, poor lighting in the room, and too long continuous use of the phone – you may experience headache, pain, eye fatigue and even nausea and sleep disturbance “, – said the expert.
BestDoctor medical analyst Polina Kozlova agrees that using PWM, you can get a fairly wide range of brightness, but at the same time, in some scenarios of use, pulses on OLED screens are supplied at a low frequency of about 100 Hz, which carries potential risks to human health.
“There is GOST R 54945-2012, which refers to the threshold value of 300 Hz as“ harmless ”to the body. Rarer blinking can cause both visual impairment and neurological symptoms, up to epilepsy, ”said Kozlova.
In order to reduce the effect of PWM on the eyes, there is a technology that some manufacturers are implementing in smartphones with OLED matrices – DC Dimming. It allows you to dim the screen by reducing the power supplied. Flickering remains, especially at brightness below 40%, but the pulses will not be as active. However, DC Dimming technology also has a drawback in the form of color distortion. This makes the picture warmer and the colors appear reddish.