No one likes the recession, but Hollywood may be an exception. why? Even if the answer is not so obvious, it is very simple. When the economy declines, the box office income will rise because consumers seek a more "economic" way of entertainment. It’s much cheaper to go out to the movies with the whole family than to go to a restaurant for dinner and then watch Broadway shows at the theatre. Perhaps unexpectedly, another form of symbiotic and reciprocal entertainment, which is currently having a positive impact on the sales of flat-panel LCD TVs that use LEDs for backlighting during the current economic downturn. Many consumers are not going to the cinema, but are happy to rent or download the recently released movie DVD and watch it comfortably in the living room. However, the difference this time is that they want to look a bit more, using the latest LED high-definition (HD) TVs. According to a recent survey by iSuppli, in the first quarter of 2009, the delivery of flat-panel TVs in the US and Canada increased to 7.8 million units, an increase of 17.3% from 6.6 million units in the same period in 2008. In addition, the survey also pointed out that even during the current economic downturn, consumers will continue to buy flat-panel TVs. The only caveat is that as disposable incomes fall, American consumers are being attracted to smaller TV sets. As a result, 32-inch and smaller TV sets have encountered supply limitations. To understand the driving forces behind the popularity of flat-panel LCD TVs with white LED backlighting, it is important to understand some of the following facts: Why should white light be used compared to other forms of lighting, such as cold cathode fluorescent lamps (CCFLs)? LED. In addition, the ability to partially turn off the LEDs can reduce motion blur. By completely turning off the LEDs between frames, image blur associated with fast moving objects is virtually eliminated. In solving this fast moving image blur problem, the very fast response speed of the LED is crucial, and CCFL backlighting LCD TVs often encounter this problem. Driving the LED requires careful design considerations, as overdrive can create heat dissipation problems that can significantly reduce light output and shorten the useful life of the LED. This has led many analog IC manufacturers to design specialized LED driver ICs to drive LEDs correctly. In order to understand the challenges of designing and manufacturing these LED driver ICs, it is necessary to understand what is needed for white LED illumination. The white LED must be driven by a constant current source so that the white spot does not move, that is, the brightness must be uniform. In addition, since the white LED is a diode, its internal forward voltage (Vf) drop must be overcome. This Vf varies with the white LED current rating and will change with temperature. The Vf of a typical 20 mA white LED varies between 2.5V and 3.9V over the entire operating temperature range. Most applications use more than one white LED, and it is also possible to configure these LEDs in parallel, in series or in series (eg, parallel strings of series LEDs). This means that a white LED driver IC must be able to supply sufficient current and voltage for a particular configuration of LEDs, while using a conversion topology that meets both the input voltage range and the required output voltage and current requirements. Busbar Insulator With Brass Screw, U-Shaped Terminal Block,Feed-Through Terminal Block,Pcb Screw Terminal Block Wonke Electric CO.,Ltd. , https://www.wkdq-electric.com
Large flat panel LCD TVs have traditionally used CCFL backlighting. However, these CCFL backlighting televisions have various shortcomings such as fast moving image blurring and inaccurate color reproduction. For the current generation of LCD TVs, it is impossible to get true black, and there is room for improvement in the dynamic range of all colors. For example, most LCD TVs offer contrast ratios of 450 to 650 cd/m2. The main problem with these HDTVs is that CCFL backlighting cannot be completely turned off or local dimming of CCFL backlighting is not possible.
In contrast, with high-brightness (HB) LED backlighting, an array of LEDs can be divided into many separate lighting groups. Each group typically consists of 8 to 10 30 to 50 mA LEDs that can be independently dimmed by a single pin for local dimming. This design provides an order of magnitude (>4 000 cd/m2) that is almost an order of magnitude higher than the CCFL design. In addition, by adjusting the brightness of the backlighting LED group with a wide dimming ratio, more midtone colors can be reproduced, thereby providing a more vivid picture.
Another driving force behind the removal of CCFLs is the desire to eliminate toxic mercury vapors in this type of illumination while improving efficiency and performance. In addition, governments in many countries have helped push this trend, and these countries have imposed new “green†measures to eliminate toxic materials, including mercury found in CCFLs. Clearly, this has helped drive LED backlighting to play an important role in the design of new LCD HDTVs.
It is estimated that from the traditional fluorescent lamp to LED lighting, the total energy demand in the world may be reduced by up to 10%, which shows that LED is more environmentally friendly. Clearly, as people strive to accelerate the reduction of total carbon dioxide emissions from energy generation, this 10% reduction in global lighting energy demand is a major contributor to this transition. So, what factors support such a huge LED backlighting growth potential? First, the current generation of LEDs is more than twice as efficient as fluorescent lamps, greatly reducing the power required to provide the required light output (measured in lumens). As LEDs continue to evolve, their luminous efficiency will continue to increase and is expected to double in the next few years. Secondly, LEDs have a lifetime of more than 100,000 hours. In contrast, fluorescent lamps have a lifespan of up to 10,000 hours and a life difference of up to 10 times.