What is the development history and trend of LCD panel backlight system?

The LCD panel itself is only glass and cannot emit light independently, and requires a backlight to display images. The plasma display technology of the same generation as LCD is a self-luminous mode, but it has been basically eliminated now. The currently highly anticipated OLED panel is a self-luminous mode and does not require a backlight.

However, since the birth of liquid crystals, it has always been supported by backlight. The backlight system of the LCD panel has undergone about three stages of changes, from CCFL backlight to LED backlight, and then to quantum dot backlight. The changes in backlight also promote changes in display structure and display capabilities.

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CCFL backlight

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

LED backlight

The LED backlight is made of compounds containing gallium (Ga), arsenic (As), phosphorous (P), nitrogen (N), etc. The principle is to use electrons and holes to radiate visible light when they recombine, so they can be used to make light-emitting diodes. The typical characteristics of this kind of backlight are small size, low energy consumption, long service life, and its own cost is not high. 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 also made possible the emergence of ultra-thin mobile phones and tablet computers.

Quantum dot backlight upgrade

However, both CCFL backlight and LED backlight have a problem, that is, the color gamut of the picture is not enough. The current backlight system, sRGB color gamut can reach 100 products very few, mainly because the backlight purity is not enough. Therefore, in order to improve the color gamut of the screen, panel manufacturers began to use quantum dot backlights, which is the third stage of the development of LCD backlights.

Quantum dots are actually nanomaterials. 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 and light film for improvement. The color effect of the backlight. Therefore, the essence of the quantum dot display is to improve the backlight. It is still the mode of blue LEDs to excite the quantum dots. Therefore, it is not an absolute upgrade of technology, but an upgrade of a modified version.

The development of LCD backlight has gone through three stages, with smaller and smaller volumes and lower and lower energy consumption. Now our thin and light displays are successfully realized, thanks to the continuous changes in backlight technology. The emergence of quantum dot backlights shows that there is not much room for further upgrades in terms of volume and energy consumption. Therefore, increasing the color gamut has become the core direction of the backlight transition, and it is also the reason for the emergence of a new generation of display technology OLED panels.

Overview of the backlight module industry

The function of the backlight module is to supply sufficient brightness and uniformly distributed light sources, so that the LCD panel can display images normally. The basic composition of the backlight display module mainly includes light-shielding glue, light-enhancing film, diffusion film, FPC and LED components, double-sided tape, light guide plate, integrated plastic and iron, reflective film, etc.

(1) Development history of backlight display module

The backlight source was first applied to the instrument display on military equipment. After nearly 60 years of development, the backlight source and the backlight display module composed of it have formed an independent discipline and industry. According to different types of light sources, backlight display modules can be divided into LED backlight display modules, CCFL backlight display modules, and EL backlight display modules. Since Sony in Japan launched the first LCD TV with LED as the backlight in 2004, the technology and performance of LED devices have been continuously improved. The LED backlight display module has the following advantages: (1) make the liquid crystal display module lighter and thinner; (2) long life, low energy consumption, and more environmentally friendly; (3) better color expression. Therefore, the current LED backlight display module has become the mainstream of the light-emitting form of the backlight display module.

(2) Development of my country's backlight module industry

The development of the backlight module industry is closely related to the development of the LCD industry. As the center of gravity of global LCD panels begins to shift to the mainland, LCD panel manufacturers have increased their demand for key components and need to reduce costs, and they tend to choose nearby backlight module manufacturers. This has brought great opportunities for the development of my country's backlight module industry.

3. The development trend of the backlight module industry

The backlight module is a key component necessary for liquid crystal display, and its brightness, chromaticity, uniformity and thickness have an important influence on the performance of the liquid crystal display module. As users continue to improve the user experience, product performance, and shape design requirements of liquid crystal display terminal applications, the backlight display module is also moving toward larger size, ultra-thin, high-brightness, narrow bezel, diversified applications, and high color gamut , Curved surface, energy saving and environmental protection.

①The backlight module develops to a larger size

Since the appearance of smart phones, the screen size of smart phones has been developing to larger sizes. Small screens have advantages in portability and one-handed control, but they are not as good as large screens in terms of video and gaming experience.

②The backlight module is developing towards ultra-thin

In the field of smart phones, ultra-thin bodies can bring users a better experience. At present, the body thickness of mainstream flagship mobile phones on the market is basically maintained between 6mm-8mm. The ultra-thin design of LCD modules puts forward higher requirements on the optical design and process manufacturing capabilities of backlight module manufacturers, and also promotes backlight module manufacturers, especially my country’s local small and medium-sized backlight display module manufacturers, to continue to invest in research and development. Ensure the brightness and uniformity of the backlight display module display even when the backlight display module is ultra-thin.

③The backlight module develops towards high brightness

Brightness is one of the main performance indicators of the backlight module. How to obtain a higher-brightness backlight module under the same conditions of light source is a technology that each backlight display module manufacturer needs to master, and it is also a need for environmental protection. The overall optical performance of the backlight module mainly depends on the performance of the light guide plate and each film material, especially the optical design and process manufacturing capabilities of the light guide plate, and the precision assembly capabilities of the finished product.

④The backlight display module develops towards ultra-narrow frame

From the structural point of view, the outer edge of the liquid crystal display module needs to reserve a part of the space to place the glass sealant and the glue iron bracket for the protective glass. Similarly, the light-shielding glue and glue iron of the backlight module will occupy a certain space of the backlight module. At present, the smart phone field has formed a trend of ultra-narrow bezels. The ultra-narrow bezel can increase the visual effect of the mobile phone and make users feel a more immersive experience. In addition, the ultra-narrow frame can also increase the screen-to-body ratio of the mobile phone, reduce the volume of the body, and make it easier to hold and touch more precise. The development trend of terminal application products towards ultra-narrow bezels also determines the development of backlight modules to ultra-narrow bezels.

⑤ Diversified development of terminal application products in the backlight module industry

At present, small and medium-sized backlight display modules are mainly used in mobile phones, tablet computers and other fields. With the diversified development of terminal product applications, small and medium-sized backlight display modules will also be more widely used in products including automotive displays, medical displays, industrial control displays, and intelligent industrial-grade handheld terminals. The diversified development of terminal application products has put forward higher requirements for backlight display modules in terms of product customization, anti-electromagnetic interference, and stability. In addition to the above-mentioned trends, in order to meet the changes in terminal applications and the social energy-saving and low-carbon environmental protection requirements, the backlight module is also developing in the direction of high color gamut, curved surface, and low energy consumption.