Analysis Of The Three Stages Of LCD Panel Backlight System Evolution

- Mar 21, 2020-

The liquid crystal panel itself is only glass, and cannot automatically emit light, and a backlight is required to realize image display. The plasma display technology of the same age as liquid crystal is a self-emitting mode, but it has basically been eliminated. At present, the much-anticipated OLED panel is a self-emitting mode and does not require a backlight.


However, since the birth of LCD, it has always required backlight to support it. The backlight system of the LCD panel has undergone changes in about three stages, from CCFL backlights to LED backlights to quantum dot backlights. Changes in backlights have also promoted changes in display structure and display capabilities.


Analysis of the three stages of LCD panel backlight system evolution


CCFL backlight


Cold Cathode Fluorescent Lamp is abbreviated as CCFL, and its Chinese translation is called cold cathode fluorescent lamp. It has the advantages of high power and high brightness, and is widely used in display and lighting fields. The earliest backlight used in displays is this cold cathode fluorescent lamp. This kind of lamp is relatively large and thick, resulting in a thicker liquid crystal panel. Therefore, the display using this backlight is not small in thickness, and it is impossible to use this kind of light in thin and light displays. In addition, the energy consumption of this cold cathode fluorescent lamp is relatively high, so it is difficult to see such a backlight system at present.


LED backlight


The LED backlight is made of a compound containing gallium (Ga), arsenic (As), phosphorus (P), nitrogen (N), and the like. The principle is that visible light can be radiated when electrons and holes are recombined, so it can be used to make light-emitting diodes. The typical characteristics of this backlight are small size, low energy consumption, long service life, and low cost itself. Therefore, after the emergence of LED backlight, it quickly replaced the original CCFL backlight. This change has led to the current popularity of thin and light displays, and has also made the emergence of ultra-thin phones and tablets possible.


Quantum dot backlight upgrade


However, there is a problem with CCFL backlights and LED backlights, that is, the color gamut of the picture is not enough. Currently, there are very few products with sRGB color gamut that can reach 100, mainly due to insufficient purity of the backlight. Therefore, in order to improve the color gamut of the screen, panel manufacturers began to use quantum dot backlighting, which is the third stage of the development of LCD backlighting.


Quantum dots are actually nano materials. Under the excitation of blue LEDs, they can emit high-purity colors. According to the size of the quantum dots, a combination of three primary colors can be configured. This combination forms a thin film for upgrading. Backlight color effect. Therefore, the essence of a quantum dot display is to improve the backlight. It is still a mode in which the blue LED excites the quantum dots, so it is not an absolute upgrade of technology, but an upgrade of a modification.