What is the working principle of LCD TV backlight?

The backlight is a light source behind the liquid crystal display (LCD), and its luminous effect will directly affect the visual effect of the liquid crystal display module (LCM). The liquid crystal display itself does not emit light, it displays graphics or characters as a result of its modulation of light.

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‍‍There is a backlight behind the LCD screen. The LCD TV relies on evenly arranged fine liquid crystal particles on the screen to "block" and "turn on" the light emitted by the backlight to restore the picture. It can be found that as long as the LCD is turned on, the backlight is working. Even if the displayed picture is a completely black picture, the backlight is also working, that is, the backlight of the LCD TV is always on. ‍‍

‍‍After power on, the backlight will light up. If the LCD pixels on the screen are all "on", the backlight will enter the human eye without obstruction, and the screen will be completely white. When displaying an image, after calculating the on-off state of each pixel through the AD conversion of the display signal, the signal is directly driven to the specific pixel to control the "on-off" of the liquid crystal pixel to the light, and then the image can be generated on the screen. When the image on the screen is like an advertising light box, the light emitted by the lamp tube in the light box enters the human eye through the patterned film.