In recent years, the flagship machines of major mobile phone manufacturers at home and abroad are basically equipped with organic light-emitting diode screens. boe 2023However, the mobile phone industry believes that LCDS are still superior to organic light-emitting diodes.

In the popularity of OLED screen mobile phones today, why are LCD users still firmly escorted?

The luminous principle of liquid crystal display and organic light-emitting diode

Both LCD and OLED are the two display technologies that have been used for the most time in China's smartphone field, BOE displaysincluding TFT, IPS, AMOLED, and PMOLED, which are based on the "enhanced version" of these two technologies.

Type of LCD and OLED display.

LCD(Liquid Crystal display) is a liquid crystal display technology that dates back more than 20 years and is widely used in electronic devices such as televisions, computers and smartphones.

The structure of the LCD screen is like two "glasses", with a layer of liquid crystal sandwiched between them. oled manufacturerThe thin film transistor is placed on the lower substrate, and the upper substrate has a color fluorescent layer. The middle layer of liquid crystal will produce different light characteristics under the action of voltage, and finally produce different colors through the color layer projection.

organic light-emitting diode (Organic Light-Emitting Diode), the full name is organic light-emitting diode, is recognized as the successor of LCD, is the best solution for the next generation of smart phone display.

Unlike LCDS, each pixel in OLeds can emit light independently. We can think of each sub-pixel as an LED light, which is composed of three sub-pixels: red, green, and blue. These arrays of sub-pixels are called OLED panels.

Simply understood, the LCD light source layer and display layer are separated, and the organic light-emitting diode display layer and light source are combined in one. At the same time, the LCD light source is fixed and cannot emit light alone.

Organic light-emitting diode (OLED) architectures have a number of additional features, including but not limited to:

The display efficiency of organic light-emitting diodes is higher than that of LCDS, which require multiple stages of "filtering" light.

OLED development no longer requires the use of backlight, the screen can be made thinner.

Using different substrate materials, OLED can also make curved or even folded display effects.

Branding and scintillation of organic light-emitting diode screens

According to the development trend of the future mobile phone market, OLED has unlimited potential. But there are also criticized shortcomings compared to LCDS, including problems with branding and flicker.

As mentioned earlier, each pixel of an organic light-emitting diode emits light, and the brightness control is driven by an electric current, which controls the light-emitting material to form different colors, that is, DC dimming.

However, due to the different materials of different cultural color painting elements, the luminous life has an impact; In addition, there are differences in the wavelength of trichromatic elements, and there are many different requirements for the development of current, such as blue, which requires higher current through. Therefore, the screen loss is too large or low brightness, it is very difficult to control the brightness of each subpixel to configure resources, then the OLED screen may be red, or "residual shadow", which is often said that "branding".

To solve this problem, manufacturers have come up with a new way to use PWM dimming instead of DC dimming. The specific operation is to make the screen blink continuously, and after reaching a certain frequency, the human eye will produce a temporary visual effect, making the screen look "always bright". If you need to reduce the brightness, simply increase the flashing interval.

This PWM dimming causes stroboscope, which is criticized by LCD users.

White areas are at high risk, yellow areas are at low risk, and green areas are at no risk.

The stroboscopic range with low health risk should be above 1250 Hz; China also has relevant testing institutions to conduct standard tests, if the light output frequency is greater than 3125 Hz, it is considered to be no strobe, and it is exempt from entering the safety zone.

Although the above report is not for mobile phone display screens, but for lighting, but also shows a pattern: the higher the frequency, the lower the risk to health development.