The picture displayed on a phone with an LCD screen looks like a complete picture, but if you zoom in many times, you'll find that the picture is made up of countless dots. These little dots are pixels, and each pixel is made up of three sub-pixels：red, green and blue. All colors can be obtained by mixing the color ratio of the three sub-pixels.
Resolution refers to the number of pixels. Take one of the pixels, from the side profile, its structure is mainly seven layers, the bottom is the backlight layer, and then the vertical polarizer, positive circuit, night capital negative circuit, horizontal polarizer, color filter.
The backlight layer of an LCD has only one purpose, which is to emit white light. After the white light has penetrated the colored filter layer, it can be changed into the corresponding color of light.
When a voltage is applied to the positive circuit, it loops through the liquid crystal layer to the negative circuit. This voltage causes the liquid crystal layer to deflect, and the liquid crystal layer acts like a shutter, blocking out some of the light rays, preventing them from escaping. By controlling the voltage, you can control the Angle of deflection of the liquid crystal layer, which in turn controls the brightness of this red sub-pixel. Similarly, by controlling the brightness of the other two blue-green sub-pixels in this way, you can mix all the colors you want by varying the brightness ratio, which is how LCD screens work.
OLED screens work much easier than LCD screens. OLED, which stands for organic self-emitting diode, has the same red, green and blue sub-pixels as LCD screens, but it lacks a liquid crystal layer and a backlight layer. It itself is a kind of specially designed self-emitting diode, you give it electricity and it lights up, the more electricity it passes on the brighter it gets, the less electricity it passes on the brighter it gets. So we can directly control the power of the LED, so we can easily control the color ratio of each sub-pixel, and finally mix all the colors you want.
