Televisions

Plasma Televisions

Plasma television is a flat, lightweight surface covered with millions of tiny glass bubbles. Each bubble contains a gas-like substance, the plasma, and has a phosphor coating. Think of the bubbles as the pixels. Essentially millions of Neon signs.

Now, think of each pixel-bubble as having three sub-pixels - one red, one green, one blue. When it is time to display an image signal (RGB or video), a digitally controlled electric current flows through the flat screen, causing the plasma inside designated bubbles to give off ultraviolet rays. This light in turn causes the phosphor coatings to glow the appropriate color making your Plasma TV provide the best video image anywhere.

Millions of RGB bubbles glowing and dimming to make a rich, vivid image.

The plasma display is one of the most exciting consumer electronics products to debut in the past decade. It's literally changing the shape of television, from the familiar CRT-type TV's that have been around for 50 years, to a sleek, nearly flat display that can hang on a wall. These new displays deliver high-definition television, and they serve both as TV's and computer monitors.

Plasma display technology is a new "emmissive" flat panel display technology which gives you the rich, accurate color fidelity of conventional Cathode Ray Tube (CRT) monitors in a large display that is thin enough to hang on the wall. It's the best way to achieve flat panel displays with excellent image quality and large screen sizes viewable in any environment. This technology known as "plasmavision" is an array of cells, known as pixels, which are composed of 3 sub-pixels, corresponding to the colors red, green and blue.

Gas in a plasma state is used to react with phosphors in each sub-pixel to produce colored light (red, green or blue). These phosphors are the same types used in conventional cathode ray tube (CRT) devices such as televisions and standard computer monitors. You get the rich, dynamic colors you expect. Each subpixel is individually controlled by advanced electronics to produce over 16 million different colors. You get perfect images that are easily viewable in a display that is less than 4 inches thick.

Basic plasma display technology has been around since the 1960's, and works this way: a mixture of neon and xenon gas fills the space between two parallel sheets of glass, which contain millions of tiny cells filled with the gas mixture. This mixture is stimulated by electrical current and is changed into a plasma. As a result, ultraviolet (UV) light is emitted. Red, blue, and green fluorescent substances in the cells absorb this UV light, then re-radiate this energy as visible light to produce the colors and images you see on the screen.

This process creates a bright, vibrant picture. And since these individual cells are creating light and color, there's no need for the large cathode ray tubes (CRT's) used in conventional and projection TV's, and the display can be very thin and relatively lightweight. Plus, the flat screen eliminates the problem of images bending at the edge of the picture, as seen in conventional TV's.

Plasma displays are not the same as an LCD screen, like those on laptop PC's or the ones that you see on commercial jetliners. Among other differences, an LCD screen uses backlighting for its illumination; plasma displays are self-lit, which produces a far brighter picture. Nor should the "flat panel TV's" you may see in stores be confused with a plasma display. These flat panel TV's, like plasma displays, do have a flat screen, so they don't have the edge distortions of a conventional curved screen. But their use of CRT's gives them the same bulky "behinds" of regular TV's, and they cannot offer the same practical advantages of plasma displays.

LCD Televisions

Liquid-crystal display televisions (LCD TV) are television sets that use LCD technology to produce images. Benefits of LCD technology include lower weight and reduced power requirements when compared to other display types. LCD television screens can also be used as computer monitors.

It had been widely believed that LCD technology was suited only to smaller sized flat-panel televisions at sizes of 40" or smaller. Early LCDs could not compete with plasma technology for screens larger than this because plasma held the edge in cost and performance. However, LCD TVs can now offer essentially the same performance.

Current sixth-generation panels by major manufacturers such as Samsung, Sony, LG.Philips LCD, and the Sharp Corporation have announced larger sized models:

• In October 2004, 40" to 45" televisions became widely available, and Sharp had announced the successful manufacture of a 65" panel.
• In March 2005, Samsung announced an 82" LCD panel.
• In August 2006, LG.Philips Consumer Electronics announced a 100" LCD television
• In January 2007, Sharp displayed a 108" LCD panel branded under the AQUOS brand name at CES in Las Vegas.

LCD technology is based on manipulation of polarized light. Two thin polarizing sheets are laminated to two glass substrates containing a thin layer of liquid-crystal. An regular 2-dimensional grid of electrodes allows each pixel in the array to be selected and activated individually.

Several LCD technologies are used for the realization of large format television screens (e.g. TN, IPS, PVA, FFS), all in combination with active-matrix addressing.

Manufacturers have announced plans to invest billions of dollars in LCD production over the next few years, with televisions expected to be a key market.

Improvements in LCD technology have narrowed the technological gap, allowing producers to offer lower weight and higher available resolution (crucial for HDTV), and lower power consumption. LCD TVs are now more competitive against plasma displays in the television set market.