PRESENTED BY:- CHANDAN(06-ECE-21)

CONTENTINTRODUCTIONWHAT IS LED TV?LED BACKLIGHTING TECHNIQUESTECHNOLOGYDIFFERENCE BETWEEN LED AND LCD TVADVANTAGE AND DISADVANTAGEFUTURE PROSPECTSBIBLIOGRAPHY

INTRODUCTIONThe LED TV is now one of the latest products

in home entertainment. LED-backlit LCD television (called LED TV by Samsung Electronics, Panasonic, Toshiba, Philips, LG Electronics, ProScan and Vizio and not to be confused with true LED displays) is an LCD TV that uses LED backlighting rather than fluorescent lights used in traditional LCD televisions.

WHAT IS LED TVOn its own an LCD panel does not produce

light. The LCD panel is a matrix of liquid crystal through which light must be passed from another source to make it visible. When an electrical current is applied to the LCD panel the light can be deflected and altered to make the colors and images visible to the viewer. Backlighting is used for this. Backlighting can be done by using CCFL(Cold Cathode Fluorescent Lamps) or LED(Light Emitting Diode).

LED (Light Emitting Diode) TVs are simply LCD TVs with a different kind of backlighting. The screen remains the same but LEDs are used in place of Cold Cathode Fluorescent Lamps (CCFL) that are found in most LCD TVs. The LEDs can come in two forms, Dynamic RGB LEDs which are positioned behind the panel, or white Edge-LEDs positioned around the rim of the screen which use a special diffusion panel to spread the light evenly behind the screen.

LED BACKLIGHTING TECHNIQUESThere are two types of backlighting techniques RGB Dynamic LEDs This method of backlighting allows dimming to occur

locally creating specific areas of darkness on the screen. This can show truer blacks, whites and PRs at much higher dynamic contrast ratios, at the cost of less detail in small bright objects on a dark background, such as star fields.

Edge-LEDs This method of backlighting allows for LED-backlit

TVs to become extremely thin. The light is diffused across the screen by a special panel which produces a uniform color range across the screen.

Sharp also has LED backlighting technology that aligns the LEDs on back of the TV like the RGB Dynamic LED backlight, but it lacks the local dimming of other sets.

TECHNOLOGYLED-backlit LCD TVs are considered a more

sustainable choice, with a longer life and better energy efficiency than plasmas and conventional LCD TVs. Unlike CCFL backlights, LEDs also use no mercury in their manufacture. However, other elements such as gallium and arsenic are used in the manufacture of the LED emitters themselves, meaning there is some debate over whether they are a significantly better long term solution to the problem of TV disposal. Because LEDs are able to be switched on and off more quickly than CCFL displays and can offer a higher light output, it is theoretically possible to offer very high contrast ratios. They can produce deep blacks (LEDs off) and a high brightness (LEDs on), however care should be taken with measurements made from pure black and pure white outputs, as technologies like Edge-LED lighting do not allow these outputs to be reproduced simultaneously on-screen.

DIFFERENCE BETWEEN LED AND LCD TVContrast and Black Levels:

Standard LCD TVs have a backlight which is constantly on during use. Dark areas are created by "turning" the light away from the LCD panel, resulting in a low contrast level and poor clarity in dark scenes. With LED TVs the light emitting diodes are dimmed locally to create deeper blacks in specific areas of the screen, which can also allow for better detail in dark scenes

Colour:LED TVs using white Edge-LED technology for the backlight do not vary hugely from standard LCD TVs. The main advantage of Edge-LED technology is that it allows for the TV to become extremely thin. However, if purchasing a LED TV using Dynamic

RGB-LED the improvement in colour is significant.

Viewing Angle:Traditional LCDs have always suffered from contrast degradation when viewed from angles of more than approximately 30 degrees from off centre. Although there have been vast improvments over the last few years, LCD still falls short of Plasma TVs when it comes to viewing angle. Viewing angle is determined by the LCD Panel itself and not the backlight. Therefore, LED TVs offer no improvment in this area.

Other Factors:A few other factors are longevity and power consumption. Although there is little history to support LED TVs, LEDs should degrade less over time than standard LCD, with most manufacturers claiming around 100,00 hours for the lifespan. In terms of power consumption there have been mixed reports, with some claiming up to a

40% power saving, whilst others report power consumption on a par with plasma. Without further evidence on these matters, I would have to class LED and LCD even.

ADVANTAGE AND DISADVANTAGEADVANTAGES: 1. Energy Efficient: Uses 40% less electricity

than any standard LCD tv. 2. No delay or warm up time: So can be

switched on and off very quickly. 3. Size: These are very thinner than any other

type of TV sets available in the market. 4. LED TVs combine the best of plasma and

LCD TVs. LED TVs show contrast similarto a plasma TV and are brighter than an LCD TV.

DISADVANTAGES: 1. Price:  LED TVs currently cost as much as

twice as much as the standard LCD or plasma sets.

2. Motion Blur: It still has motion blur as in the CCFL LCD TVs.

3. EDGE lit LED TVs have some lighting problems especailly at the corners

FUTURE PROSPECTS According to the Analyst and the market

survey. LED Backlight LCD’s and Plasma will dominate the market for the next 5 years and then they will be slowly replaced by emerging technology such as OLED or The Organic LED tv which is an advancement in the LED TV series. But there still are problems to be solved. Like the Decaying nature of

the Organic material.

BIBLIOGRAPHYGOOGLE : THE SEARCH ENGINE.WIKIPEDIA : THE ONLINE ENCYCLOPEDIAWEBSITES :

WWW.LEDHDTELEVISIONS.COM WWW.LEDTELE.CO.UKJOURNALS: WWW.LEDMAGAZINES.COM