Various Backlight systems in LCD Televisions
LCD televisions are back to its glory with the ban of Plasma televisions. With all leading brands curbing plasma display market, the cosmopolitan leaders in LCD display domain is striving hard to come forward with the best displays promising pristine video quality and immaculate audio settings. Backlight settings is one important factor that affects the quality of the image rendition no matter how good other specs of that display are.
Backlight system has a key role in controlling the colour reproduction of the screen. Moreover temperature, lifespan of display, resolution, picture clarity, power consumption, etc are also dependent on the backlight system. Liquid crystal molecules in LCD televisions does not emit light, and hence backlight system plays a pivotal role in those displays. There are mainly three backlight systems used EL(Electro Luminescent), CCFL system (Cold Cathode Fluorescent Lamp) and LED(Light emitting Diode) system.
EL system is used in small LCD displays, like those in calculators or small display boards. The EL backlight system is not used in LCD displays since they are not capable of providing quality output especially in the case of big screens. CCFL system is one of the most commonly used backlight system in displays, and now new variants of CCFL is also developed by the display pioneers like Sony, Toshiba, etc. CCFL system is akin to thin fluorescent lamps, and does not emit heat while producing light, thereby increasing the lifespan of displays. In CCFL backlight system light is generated by emitting electrons randomly.
Wide Colour Gamut CCFL is an advanced version of CCFL that provides better colour gamut. Gamut can be defined as the range of colours that can be reproduced in a given space or device in a particular instance. The WCG CCFL backlight system offers much better colour reproduction, that is in a more natural way compared to EL and CCFL. It is atleast 70% better than the usual CCFL NTSC coverage. WCG CCFLs are used in most of the high-end leading brand displays like Sony, Samsung, etc. Moreover intelligent sensor is incorporated in Samsung and LG displays to alter the backlight settings of the display according to the ambient lighting conditions. Sony has come up with room light sensors for the same purpose.
LED backlight system is more sophisticated than WCG CCFL system, and has an upper hand on CCFL system. LED system is much brighter than other backlight system, moreover it is more efficient and increases the display lifetime too. Much lower DC voltages are needed for the working of LED backlight system, which makes it energy efficient too. This system has upper sway in producing higher optical output for the given electrical input and optimisation of colour gamut is also possible in this system. Wide range dimming capability is yet another merit of this backlight system. Short response time and exceptional blacks are added bonus of LED backlight systems.
Sony has come up with LED backlit Qualia 005, which is the first LED Backlit home entertainment display in the world, and it ensures 150% better colour rendition than conventional televisions.There are certain factors that makes CCFL backlight systems more desirable than LE system. It includes the heavy cost of production and implementation. This affects the price of telly too, which is an obsolete trend in the present market where display prices are slashed considerably. Thin profile is the “In Trend” in LCD domain, and by using LED backlight system, minimalist design of LCD is hectic with LED backlight systems.
While using WCG-CCFL backlight system, the benefit of Wide Colour Gamut is obtained only if the display has Deep Colour Technology. Otherwise WCG-CCFL and CCFL is not going to render any difference in video output. RGB LED settings are used in many of the premium LCD Televisions like Sony 70 XBR, some of the NEC models, Samsung models, etc. They offer 105 % better colour gamut than NTSC standards. With the increasing pressure to launch innovative products with high quality video output many of the televisions has already started adopting LED backlight techniques.
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