In the next three years, LED backlight technology will become the leading product technology in China's flat-panel TV industry.

1. LED backlight development in ultra-thin direction

(1) LED thinning, high power and thinner light guide plate

According to market research firm Display Search, global LED LCD TV sales in 2009 were about 4.09 million units, accounting for only 3% of the entire flat-panel TV market, but sales will soar to more than 123 million units in 2014, accounting for the entire flat-panel TV. Market share also soared to 53%.

LED color TV is not a new display technology in nature, but it replaces the traditional cold cathode fluorescent lamp with a new LED light source technology. However, this kind of LCD TV with side-mounted LED backlight has a slim body that is difficult to compare with traditional products: the thickness of LED TVs produced by most famous manufacturers is about 2cm, which is unmatched by traditional LCD TVs. .

LED TVs mainly compete for not only thickness, but also more economical, energy-saving power consumption, and better image quality. The technical performance advantages of many aspects are the core reasons for the rapid growth of the LED TV market.

(2) No borders

Although LCD TVs can't really achieve "no borders" - this is just an exaggerated description of the ultra-narrow bezel. However, industry experts have predicted that the borderless products will become another peak in the design of LCD TVs after LED ultra-thin.

In fact, as early as three years ago, many LCD companies, including Samsung, have invested in the development of ultra-narrow bezel products. However, these technologies are mainly used in engineering display fields, such as LCD TV splicing walls. In April of this year, Samsung's LCD screen wall product launched in the domestic market has a narrowest frame thickness of less than 3mm. Since then, companies such as Sharp, LG, and Taiwan's Chi Mei have also introduced liquid crystal display panels that can meet the thickness of the millimeter-level frame for the whole machine enterprise to choose. The support of many upstream manufacturers, on the one hand, illustrates the practical value of borderless technology, on the other hand, it shows that the technical bottleneck of LCD TVs that make millimeter-level or even smaller-level frames has been basically broken.

According to Figure 4, (a) is a direct-type backlight. In order to reduce the light-mixing height, the number of lamps is required to be relatively large, which is now mass-produced; (b) is a side-lit backlight, which is now developed. Four sides of the light, need six light strips, the light is two chips packaged in one, later with the improvement of the efficacy of LED lights, will develop into two sides of the light; (c) need four light strips, is also two chip package (d) is also the light on both sides, only 2 light bars, light on the short side; (e) for the later development goals, single-sided light, such as the current NB products and MNT products, single chip package To meet customer requirements, to meet the cost reduction, improve assembly efficiency, reduce power consumption, energy saving and environmentally friendly products.

2. LED backlight meets the market green and environmental protection concept

At this stage, large-size TV backlights are mainly based on direct-type. Now EU standards, domestic standards, products must comply with RoHS standards, UL standards, and later added halogen-free requirements. The CCFL products that are used in large quantities now contain Hg substances in the lamps. Due to this characteristic, the exemption of the substance is added to the standard, that is, the substance is qualified and available in a certain amount. However, the substances containing Hg in CCFL are still contrary to the current environmental protection requirements. The current products require green and environmental protection. The notebook computers in the product backlights have no Hg requirements for backlight products from the use of LEDs. The emergence of large-size LED backlights is in line with the current market requirements for green and environmental protection.

3. Side-lit dynamic backlight and low-power technology

Nowadays, the large-scale TV products that are generally mass-produced use the direct-type CCFL as the light source. This type of drive requires Invertor technology. Due to power problems, the use of CCFL as a light source consumes a lot of power, with the technology. Increasingly, the power consumption achieved by this technology is already close to the limit. With the introduction of high-end products direct-lit LED backlights, the technology to reduce power consumption has reached a new level. With the emergence of high-power LEDs and improved efficiency, the direct-type power consumption is continuously decreasing. The direct-lit LED backlight also has a breakthrough technology. Local dimming is also called dynamic backlight technology, which greatly reduces the power consumption of the backlight and improves the contrast of TV products. The number is relatively large, the thickness of TV products is relatively large, and the aesthetics and flexibility are slightly worse. The later-launched side-illuminated LED large-size backlight technology combines the advantages of ultra-thin, beautiful, and low power consumption. It is expected that the local dimming technology can be greatly reduced in the large-size backlight of the side-illuminated LED, which can greatly reduce the power consumption of the backlight. The direct-lit LED dynamic backlight is combined with image processing. In the dark place, the LED reduces the current or voltage. This requires relatively high technical requirements for the driver circuit, but greatly reduces the power consumption of the backlight. The side-in LED backlight is controlled by LED cross-over to achieve regional control and reduce power consumption to a certain extent. Side-in LED large-size backlights combine various advantages, and if breakthroughs are made in local dimming, it will be another improvement in technology.

4. Consider direct packaging of heat sink materials on the LED package

An important issue to be faced in the development of large-size LED backlight products is the heat dissipation problem. The direct-type LED large-size backlight has a certain amount of light-mixing height, which helps the heat dissipation, and the heat-dissipating plate is correspondingly formed on the entire LED large plate to achieve the heat dissipation effect. Since the power of the LED lamp is relatively high now, and a certain amount of energy is released in the form of heat, the backlight has strict requirements on thermal reliability, and the overheating affects the performance of the circuit component, reduces the luminous efficiency of the LED lamp, and causes wrinkles in the film material. The phenomenon causes the backlight mura (uneven, speckled) to be poor, and the local temperature of the backlight is overheated. When the module is aging test, the liquid crystal is unstable. Now, the large-size LED side-illuminated backlights that are mass-produced are required to reduce the number of light bars, increase the power of the lamps, and require higher heat dissipation for the LED light bars. The current technology is to use an aluminum substrate for the light bar. The light bar needs a heat dissipation strip to be assembled on the backlight, and the structure should be matched with better heat dissipation. However, as the light bar is reduced, the number of corresponding lamps is reduced, and the brightness of the lamp is increased. It is a challenge to the prior art. The later trend focuses on the luminous efficiency of LEDs. The higher the luminous efficiency, the lower the heat generated. From the perspective of LED lamp packaging technology, the heat dissipation material is directly encapsulated into the interior to achieve better heat dissipation effect, and as the packaging technology is improved, the heat dissipation of the LED lamp will be better. And now every LED manufacturer is studying the module of LED light. This technology is to pack multiple chips under one module and heat-dissipate accordingly. The light mixing in the Light bar module is optimal, and the ceramic package is used. Good heat dissipation, power boosting to 100lm/W.

5. Straight down ultra-thin technology

At this stage, large-size direct-lit LED backlights are developing toward large-size side-entry LED backlights, following low-carbon, green, environmentally friendly, ultra-thin, high-color display requirements, and side-in LED backlights in later dynamic regions. Controlling the backlight does not achieve optimal values ​​and requires thinner backlighting technology. Through the micro-structure processing of the LGP and printing on the light guide plate, the LED lamp achieves the light mixing requirement at the shortest distance, and improves the transmission efficiency of the light source in the LGP, changing the original side-entry type due to long-distance transmission. The problem of light loss. At the same time as the large-size direct-type backlight is ultra-thin, the local dimming technology is completed to achieve low power consumption, and RGB LED or high-power white LED (RGB phosphor) is used on the basis of direct-type technology to achieve ultra-thin, Low-power, high-color backlight products.

6. The middle and lower reaches of the supply chain are increasingly perfect

With the development of large-size TV backlight technology, LEDs have gradually replaced CCFL. In notebook computers, LEDs have been used in large quantities, and Monitor is also rapidly increasing. The supply of LED lights is now a concern of everyone. Now the backlight manufacturers are bound to the LED packaging factory, or the backlight factory has its own LED packaging factory. In the supply chain issue, the backlight manufacturers are considering LED packaging factory is its own partner. The global patent chip is in short supply. If you have your own LED factory, you must have certain advantages in the supply chain. With the development of large-size LED backlights, the demand for LED lights is growing. How to choose LED lights and how to cooperate with LED lamp factories is a top priority.

7. New technologies continue to emerge

Since multiple LEDs on the Light bar replace one CCFL tube, the brightness and chromaticity of each LED are required to be in the same Rank range, which increases the cost of the LED. Due to the chip, the mixed phosphor and the packaging technology, the LED is divided into multiple brightness files and more color blocks, and the mass production requirements of each backlight manufacturer are different, but only a small part of all the blocks are packaged. A large portion of the product will be scrapped, increasing the cost. Now some manufacturers have introduced the basic chroma mixing technology of the same brightness file to achieve the white light phenomenon, and the required chromaticity range in the backlight state can reduce the cost to a certain extent. Now under the direct-lit LED backlight, through the local dimming technology, using the circuit drive to complete the mixing technology of different brightness and different chromaticity, to meet the mass production requirements, and successfully reduce the LED cost.

There are many new backlights being developed at this stage. Japanese companies have successfully developed a field emission type high-brightness backlight using carbon nanotubes, which is suitable for large-screen displays such as LCD W (widescreen LCD). In addition to high luminous efficiency, low energy consumption and high brightness, it also features mercury-free, long life and high speed response.

2010 is an important year for the development of large-size LED backlights. LED backlights rely on mercury-free green environmental protection, regional dynamic control backlights, low-carbon energy-saving, ultra-thin streamline appearance, and vivid display with high color reproduction. The earth has pushed the pace of LEDs to replace CCFL. Each backlight manufacturer and LED manufacturers reached a cooperation relationship, and jointly proposed a solution to combine with the latest technology of large-size light guide plates. Ultra-thin, energy-saving, environmentally-friendly, high-quality LED backlights will surely become the next strong trend in backlight development.