To understand the difference between OLED and LCD screen, first we need to explain the principle of its operation.

LCD backlight and OLED self-illumination

First, please see below diagram of LCD and OLED.

What’s the difference between OLED and LCD Display?

The principle of illumination of the LCD is mainly the backlight layer, which is the part of Back-light in the above picture. This part is usually composed of a large number of LED backlights. It has only one function, which is to display white light, but white light cannot form an image, so we Add a layer of colored film to the white backlight layer. The white backlight will show the color after penetrating the colored film, but we need to adjust the ratio of red, green and blue. Shooting through red, green and blue, so we add a control valve between the backlight layer and the color film. This is the layer of liquid crystal in the picture, which is what we call the liquid crystal layer. This layer can be changed by changing the voltage. Control the degree of opening and closing, so that there is more light to shoot out, and less light is emitted when the opening and closing is small, so that we can control the amount of white light, make the ratio of red, green and blue can be adjusted. This is how the LCD screen works.

For OLED, OLED do not need backlight layer like LCD, and do not need the liquid crystal layer. As long as it is energized, it can light up, so OLED is like a screen with many small color bulb combinations.

LCD disadvantage

LCD also has a fatal problem, that is, the liquid crystal layer can not be completely closed, so if the LCD displays black, some light will pass through the color layer, so the black of the LCD is actually grey, mixture of white and black color, not pure black.

OLED is different. When the OLED is black, it can directly turn off the pixels in the black area to achieve almost pure black effect.

In addition, due to the existence of the backlight layer, the backlight of the LCD display is very easy to leak out from the gap between the screen and the frame. This is often said that the display leaks light, and the LCD cannot completely avoid light leakage.

Advantages of OLED

Thickness: Due to the presence of backlight layer and liquid crystal layer, LCD has much thicker thickness than OLED. Therefore, OLED screen is very easy to make mobile phone or display thin, which has no effect on the display. It is a qualitative leap for mobile phones. A thin screen allows you to plug in more components to enhance the experience of other parts.

oled and tft lcd
Bendability: because of the presence of the liquid crystal layer and the backlight layer, the LCD screen cannot be bent sharply, and the OLED can be folded almost as easily as the origami. Samsung’s curved screen is supported by OLED technology.

Color: Contrast refers to the ratio of white to black. The higher the contrast, the thicker the picture. The LCD has a backlight layer, black is not pure black, so the contrast is difficult to make high, OLED black does not emit light, so you can directly close the black area pixels, then black is almost 0, so the theoretical contrast can be said to be infinite . OLED is like oil painting, the color is pure and delicate, LCD is like a watercolor stroke, the color is faint and light. I think people can distinguish the difference between high-end OLED and LCD at a glance.

lcd and oled contract difference
Separate lighting: when LCD is open, the entire backlight layer is fully open, so the LCD is either fully open or fully closed, and each pixel of the OLED is independent, so the OLED can individually illuminate certain pixels, and this feature can be used in a very convenient function – aways on display, after the screen is turned off, lighting a few pixels with low brightness to display time, light, and notification, so Samsung mobile phone can not open the screen Understand what is the application message, double-click the message icon to light the screen. This feature can greatly reduce the number of times of lighting screen, and indirectly saves power. Once you get used to it, you will fall in love with this feature.

Power consumption: OLED work independently due to pixel points, the LCD backlight is fully open no matter what color is, so the LCD is destined to consume electricity.

Screen response time: We know that the color of the picture is displayed by the pixel points, and it takes time for the pixel to change from color 1 to color 2. This time is called gray-scale response time, if the gray-scale response time is too Long, when the screen is swiftly slid, the pixel does not have time to change from color 1 to color 2, resulting in residual image. Visually, smear will appear, and smear will greatly affect the visual perception. The OLED has almost no delay, and the LCD screen, Even if it is Apple’s top LCD, the smear is still exist.

The disadvantage of OLED

Burning screen: The defect of OLED is also obvious and fatal. The LCD screen is inorganic material. Its aging speed is much slower than that of organic material OLED. Therefore, the life of OLED organic material is not as good as LCD, and it is more deadly. OLED because each pixel is self-illuminating, not the whole block of the LCD is bright, which will cause the OLED to work at different times for each pixel. Some pixels show blue for a long time, then his blue The color attenuation will be more than other pixels. When the blue color is displayed later, the blue color of this pixel is lighter than the rest. The same for red and green, so OLED burning screen is very easy to happen. (residual residue caused by uneven screen aging

Strobe: The screen needs to control the brightness. For LCD, we can control the brightness (DC dimming) directly by adjusting the voltage of the backlight layer. OLED will have uneven jelly effect at low voltage, so OLED can not adjusts the brightness by control voltage, and the method of controlling the brightness of the OLED is to continuously switch on and off. The number of times of the switch is high to a certain extent, and the naked eye cannot see it (PWM dimming). PWM dimming is actually the brightness of the screen is fixed, it adjusts the continuous reading by changing the time of lighting the screen. If the screen brightness is 100%, then keep the screen open in all the time, if the brightness is 80%, then 80% of the time to open the screen, 20% of the time to close the screen, if 50% brightness, then 50% of the time to open, 50% of the time to close. At low brightness, because the screen is off for too long, our naked eyes will obviously notice that the screen is on and off. In fact, many people’s misunderstandings are that the strobe frequency of the screen is low. Actually it is not. Because the screen is off for too long, the black field interval is too obvious.

Low pixel density: We know that the pixels make up our screen, so the more pixels there are, the more clear the screen is, but the OLED screen pixel arrangement will cause the two phones to have the same resolution. However, the screen resolution will be less than 1/3 of the root number, so in the case of the same resolution, the OLED screen is not as clear as the LCD.

the left side is LCD, right side is OLED.