7 Trends Of LED Backlight Development

LED backlights rely on the advantages of mercury-free green environmental protection, regional dynamic control backlights, low carbon and energy saving, ultra-thin streamline appearance, high color reproduction and realistic display. The earth has promoted the pace of LED replacing CCFL. Various large backlight manufacturers have reached a cooperative relationship with LED manufacturers to jointly propose solutions and combine the latest technology of large-size light guide plates. Ultra-thin, energy-saving, environmentally friendly, and high-quality LED backlights are bound to become the next strong trend in the development of backlights.

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

　　1. LED backlight is developing towards ultra-thin

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

According to the market research organization Display Search, the global sales of LED LCD TVs in 2009 was 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 by 2014, accounting for more than 123 million flat-panel TVs. The market share also soared to 53%.

　　LED color TV is not essentially a new display technology, but the application of a new type of LED light source technology to replace the traditional cold cathode fluorescent lamp. However, this LCD TV with side LED backlight has a slim body that is unmatched by traditional products: At present, the thickness of LED TVs produced by most famous manufacturers is about 2cm, which is incomparable to traditional LCD TVs. of.

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

　　 (2) Borderless

　　 Although it is impossible for LCD TVs to truly be borderless-this is just an exaggerated description of ultra-narrow bezels. However, industry experts predict that borderless products will become another peak of LCD TV process design after LED ultra-thin.

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

According to Figure 4, (a) is a direct-lit backlight. In order to reduce the height of light mixing, a larger number of lamps is required, which is now generally mass-produced; (b) is an edge-lit backlight, which is now developed to For light on four sides, 6 light bars are required. The lamp is two chips packaged in one. As the efficiency of the LED lamp increases, it will develop into light on both sides; (c) 4 light bars are required, which is also a two chip package. Together; (d) It also receives light on both sides, only 2 light bars, enter the light on the short side; (e) is the later development goal, single-sided light, such as current NB products and MNT products, single chip package , Meet customer requirements, reduce costs, improve assembly efficiency, reduce power consumption, energy-saving and environmentally friendly products.

　　2. The LED backlight conforms to the market's green and environmental protection concept

　　 At this stage, large-size TV backlights are mainly direct-type. Now EU standards, domestic standards, and products must comply with RoHS and UL standards, and halogen-free requirements have been added later. Nowadays, a large number of CCFL products used in lamps contain Hg substances. Due to this characteristic, an exemption for this substance has been added to the standard, which means that the substance is qualified and usable under a certain amount. However, the Hg-containing substances in CCFL still violate the current environmental protection requirements. Current products require green and environmental protection. In the product backlight, notebook computers start to use LEDs to meet the Hg-free requirements of backlight products. The emergence of large-size LED backlights is just in line with the current market green and environmental requirements.

　　3. Side-emitting dynamic backlight and low power consumption technology

Nowadays, the mass-produced large-size TV products all use direct-type CCFL as the light source. This drive requires Invertor (invertor) technology. Due to power problems, the use of CCFL as a light source consumes more power. With the development of technology With continuous improvement, the power consumption achieved by this technology has approached the limit. With the introduction of high-end products, direct-lit LED backlights, the technology to reduce power consumption has reached a step. With the emergence of high-power LEDs and the improvement of efficiency, the direct-lit power consumption is continuously decreasing. There is also a breakthrough technology for direct-lit LED backlights, local dimming (area control), also known as dynamic backlight technology, which greatly reduces the power consumption of the backlight and improves the contrast of TV products. However, LEDs are required The number is relatively large, and the thickness of TV products is relatively large, and the aesthetics and flexibility are slightly worse. Later, the side-emitting LED large-size backlight technology, which is launched later, combines the advantages of ultra-thin, beautiful, and low power consumption. It is expected that the local dimming technology can be used to greatly reduce the power consumption of the backlight source on the side-emitting LED large-size backlight source. The direct-lit LED dynamic backlight is combined with image processing, and the LED in the dark place reduces the current or voltage, which requires relatively high technical requirements for the drive circuit, but greatly reduces the power consumption of the backlight. The side-type LED backlight is controlled by LED crossover to achieve regional control and reduce power consumption to a certain extent. The side-type LED large-size backlight combines various advantages. If a breakthrough is made in local dimming, it will be another improvement in technology.

　　4. Consider direct packaging heat dissipation materials on LED packaging

　　 Now that large-size LED backlight products are being developed and designed, one of the most important problems to be faced is heat dissipation. The direct-lit LED large-size backlight source has a certain amount of light mixing height, which helps to dissipate heat to a certain extent, and a corresponding heat sink will be made on the entire large LED board to achieve the heat dissipation effect. As the power of LED lights is relatively high, and a certain amount of energy is released in the form of heat, and the backlight has strict requirements on thermal reliability, overheating affects the performance of circuit components, reduces the luminous efficiency of LED lights, and causes wrinkles in the film. The phenomenon causes poor mura (unevenness, spots) of the backlight, overheating of the local temperature of the backlight, and unstable operation of the liquid crystal when the module is subjected to the aging test. However, the mass-produced large-size LED side-emitting backlights are now required to reduce the number of light bars and increase the power of the lights, which requires higher heat dissipation of the LED light bars. The current technology is that the light bar uses an aluminum substrate. The light bar needs a heat dissipation bar when assembled to the backlight. The structure must be better for heat dissipation. However, as the light bar decreases in the later period, the number of corresponding lights decreases and the brightness of the light increases. It is a challenge to the existing technology. 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 packaged inside to achieve a better heat dissipation effect. With the improvement of packaging technology, the heat dissipation of LED lights will be better. And now, various LED manufacturers are studying LED lamp modules. This technology is to package multiple chips under one module and perform heat dissipation accordingly. The light mixing in the Light bar module achieves the best state, and the use of ceramic packaging is more effective. Good heat dissipation, and the power increase is developing towards 100lm/W.

　　5. Direct type ultra-thin technology

At this stage, large-size direct-lit LED backlights are developing to large-size side-lit LED backlights. Following the display requirements of low-carbon, green, environmentally friendly, ultra-thin and high-color, the dynamic area of side-lit LED backlights in the later period Controlling the backlight does not reach the optimal value, and it needs to be thinner in direct-lit backlight technology. By processing the microstructure of the LGP and printing on the light guide plate, the LED lamp can meet the light mixing requirements at the shortest distance, and the transmission efficiency of the light source in the LGP is improved, and the original side-entry type is changed due to the long-distance transmission. The problem of light loss. While the large-size direct-lit backlight is ultra-thin, local dimming technology is completed to achieve low power consumption requirements, and RGB LEDs or high-power white LEDs (RGB phosphors) are used on the basis of the direct-lit technology to achieve ultra-thin, Low-power, high-color backlight products.

　　6. The upstream, midstream and downstream of the supply chain are getting better

　　 With the development of large-size TV backlight technology, LEDs have gradually replaced CCFLs. In notebook computers, LEDs have been widely used, and monitors are also rapidly increasing. The supply of LED lamps is now a problem that everyone is concerned about. Now major backlight manufacturers are bound to LED packaging factories, or backlight manufacturers have their own LED packaging factories. In terms of supply chain issues, major backlight manufacturers are considering The LED packaging factory is accepted as its own partner. The global supply of patented chips is in short supply. If you have your own LED factory, you will have a certain advantage in the supply chain. With the development of large-size LED backlights, the demand for LED lamps is increasing. How to choose LED lamps and how to cooperate with LED lamp manufacturers is the most important thing.

　　7. New technologies continue to emerge

　　 Since multiple LEDs on the Light bar replace one CCFL tube, the brightness and chromaticity of each LED lamp are required to be in the same Rank (range) value, which increases the cost of the LED. LEDs are divided into multiple brightness files and more color blocks due to chips, mixed phosphors, and packaging technology. The mass production requirements of various backlight manufacturers are different, but only a small part of all the blocks, so packaged A large part of the product will be scrapped, increasing the cost. Now some manufacturers have introduced chromaticity mixing technology based on the same brightness profile to achieve the white light phenomenon, and the required chromaticity range under the backlight state can reduce the cost to a certain extent. Now under the direct-lit LED backlight, through the local dimming technology, the use of circuit drive, complete the mixing technology of different brightness and different chromaticity, meet the demand for mass production, and successfully reduce the cost of LED.

　　 There are many new backlight sources under development at this stage. A Japanese company has successfully developed a field emission type high-brightness backlight using carbon nanotubes, which is suitable for large-screen displays such as LCD W (widescreen liquid crystal). In addition to high luminous efficiency, low energy consumption and high-brightness luminescence, it also has the characteristics of mercury-free, long life and high-speed response.