Technology

3. Are you planning to Buy HD TV

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2. LED TV - Technology with a Bright Future

- B. Ramamoorthy (Source: Tommy Hammerman)

How LED Works
(The Technology behind Light Emitting Diodes)

Television screens have come a long way from the standard box sets that first debuted in the 1920s. Since then, technological advancements have provided consumers with a variety of brighter, wider and clearer screen display choices— available in Light Emitting Diodes (LED), Liquid Crystal Display (LCD) and plasma. These screens differ in their longevity and color as well as their environmental effects. Plasmas, which have been the longest running product on the market, have been popular for resiliency and good contrast ratio, while LCDs have been well received for their energy efficiency. But the newest of the technology bunch, LED, is an improvement of LCDs; continual developments make these screens thinner, allowing for the greatest portability and a luminous look. Below is an explanation of LED technology and how it compares to other display types. 

What are LED TVs?

Manufacturers describe LED TVs as an LCD set with a different backlighting system. LCDs use fluorescent lamps as backlighting, while LEDs are composed of light emitting diodes. In technological terms, LEDs radiate light when a current passes through its semiconductor diodes in a forward motion. This process involves electrons that are transmitted via a semi-conductor and are placed in various energy levels during transit. The electrons are illuminated after they reach a lower energy level, which produces television images. Experts say that the larger LED color displays use a three-LED pixel.

LED Look 

Besides television, LED technology is also found in numerous applications, including traffic lights, digital clocks, watches, and microwave oven time displays. In TVs, LED screens are efficient because they are generally produced in very thin screen sizes, which is good for portability purposes. Advancements on the backlighting technology allow clear picture quality and low power consumption (in contrast to high-energy plasmas). LEDs can also be viewed from a wide angle, and backlighting produces a darker, black coloring. Companies claim that the lifespan of these televisions depends on the life of the backlighting, and can last over 100,000 hours. Because of their slim look and good color contrast, LEDs are generally most expensive of the screen options. LEDs are often used as computer monitors and are a popular screen choice for video game use.

LED vs. LCD and Plasma Compositions 

Plasma screens were introduced to the market around the same time as LCDs (which arrived later). LCD screens are backlit with a fluorescent light, and operate by the same technology as a pocket calculator. Generally, LCDs are considered to be the least eco-friendly technology because mercury is involved in producing images. While traditional LCDs feature different styles of florescent lights, LED models have different backlighting styles.  

Plasma television screens are usually thicker than LCD and LED sets. They work by using a gas that turns into plasma via an electronic current. The pictures produced on plasmas are usually highest quality (and are generally considered better than the two other mediums), and can be viewed from very wide angles, which is why these screens are a popular consumer choice. The drawback of plasmas (in comparison to LEDs) is that they are bulkier and use a high amount of energy consumption to light up, although they are generally cheaper. Plasmas are also prone to screen glare. Overall, plasmas are considered to have a better contrast picture than LEDs. Because these televisions use miniscule plasma cells that produce a picture with an electrical charge, they can deactivate the source of light off parts of the screen, according to manufacturers. This produces a high-quality contrast (darker blacks and brighter light colors).

Variations of LEDs

Manufacturers produce a few varieties of LEDs. These devices can be maneuvered to produce a dimming effect, which involves a LED light panel that may be controlled (individually or via banks) to improve the television contrast. LED edge lighting is another option, and this works by surrounding the edge of the panel with LED lights. Generally, the LED edge models are the slimmest screens available. The lights on these screens are equally distributed at the edges of the screen (or the panel) which allows for a very thin frame. The frame, in turn, is effective for applications such as portable touch screen devices.

One of the newest technologies, and perhaps the reason why LED screens are such distinguishable modern products, is the capability of Organic Light Emitting Diodes (OLED) technology. These devices are “emissive” as thin organic layers act as a source of light. An electro-luminescent light is produced from the organic carbon material used, creating a bright picture and the capability for an extremely thin screen, bright pictures and a low energy consumption.

1. Tell me How it Works?...

How Does A Blu-ray Disc Work?

- B. Ramamoorthy

The main feature of the Blu-ray disc that separates it from a normal DVD is its storage capacity. The Blu-ray disc has five times more storage capacity than DVDs. It can hold 25GB in a single layer disc and 50 GB on a dual layer disc. A Dual Layer Disc can have over 9 hours of high-definition (HD) video on a 25GB disc and over 22 hours of standard-definition (SD) video can be had on a 50GB disc. The Blu-ray disc also offers other great features, chief among these being a new dimension of interactivity which allows you to connect to the internet and download a wide variety of content.

In addition, you can also record HDTV without resulting in any loss of video or audio quality. And Blu-ray has a transfer rate of data of 36Mbps (megabits per second) so with a Blu-ray disc 25 GB of data can be recorded in around one and a half hours. Essentially the Blu-ray disc is able to accomplish this because of the way it is manufactured and how it reads the data stored on the disc. The Blu-ray Disc is 1.2 millimeters thick, same as a DVD.

With Blu-ray, data is stored directly on top of a 1.1mm thick polycarbonate layer, then a protective hard coating layer is put on the outside of the disc. This differs from a DVD in that, data is stored on a DVD between two 0.6 mm polycarbonate layers. This stacking of layers can cause the laser used to read the data, to split into two different beams, resulting in problems reading the disc correctly. Having data stored on top prevents the Blu-ray disc laser from splitting.

The laser used to read the data is the main technical development that separates the Blu-ray from the DVD. Video and Audio data is stored digitally on spiral grooves which run from the middle of the disc to the outer edges. To play the disc a laser is needed to read these grooves. The smaller the grooves the more data can be stored on the disc, however, with smaller grooves a more precise laser is required.

Unlike the DVD, which uses a red laser, the Blu-ray uses a Blue Laser. This blue laser has a shorter wavelength. The beam is more precise and can read the grooves on the Blu-ray disc which are made twice as small as the ones on a regular DVD. This is why the Blu-ray disc can hold so much data and contain so many new features. For these reasons, the Blu-ray disc will probably become the medium of choice for the foreseeable future, until something better comes along.