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Gas Plasma

What is it?

Gas plasma technology is a new way to build video and computer monitors. Essentially plasma units have the brightness and look of a CRT monitor, but they offer a much larger image and are thin and light enough for any application. Like LCD displays, plasma monitors do not exhibit the distortion and loss of clarity in the corners inherent to CRTs.

In July 1964, the idea for plasma display panels was first created the University of Illinois (USA). During that time, it was just some light source created in laboratory experiments. By the late 60's, scientists were able to construct geometric shapes with the advancement of technology. However, further development was limited, scientists were restricted by the better materials that were available back then, therefore the screens were small, and image quality was low. Today, due to the progression in high speed digital processing, materials and advance manufacturing technology, has made full colour, bright plasma displays possible. Once what was only thought of as Science Fiction is now available and ready to use in a host of new and exciting ways.

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How it works? 

Figure 14: How gas Plasma work

Plasma displays are unique compared with other display technologies. Inside this thin panel is a fixed matrix of imaging pixels, just like an LCD. The zoom in to those pixels resembles small capacitors with three electrodes (corresponding to the color red, blue and green). An electrical discharge across these electrodes sandwiched between two glass panels excite the tiny pockets of noble gas, mainly xenon and neon, into an ionized form of matter called plasma. This process results in the production of UV light, which in turn reacts with red, green and blue phosphor in each pixel to emit visible light. Unlike traditional displays, where the image is scanned across the screen, images from plasma technology are created by adjusting the brightness, color and contrast of each pixel. All these pixels can also light up simultaneously, so there is no scanning to distort the image as with a CRT. Therefore, having no electron beam, back lighting or light polarization, the image is inherently sharper, brighter and perfect from edge to edge.

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Advantages of plasma

  • Very bright
    Less
    sensitive to ambient light than most LCD, plasma monitors have the brightness and contrast of CRT-based sets.
     

  • Effective visual field angle
    Spectators can enjoy sharp, on-screen images from virtually any viewing point (excess of 160 degrees, both horizontally and vertically) rather than simply front-on.

Figure 15: Effective visual field angle

  • Accurate display characteristics
    The use of a true flat-panel screen ensures images displayed are always perfect and distortion-free. Entire image always in perfect focus, not just in the center, but all the way to the corners.
     

  • No backlighting
    Unlike an LCD, plasma does not require backlighting or polarization. This produces sharper images visible in any setting, even in direct sunlight.
     

  • Energy saver
    Consume lesser power than CRTs.
     

  • Thin and lightweight
    At only 4" - 6" thick and about 60-100 lbs., making them installation-friendly.

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Disadvantages of plasma 

  • Black screen
    By nature, plasma displays have a potential problem with black level. Since the cells always receive power, there is a small amount of light emanating from every cell, even those representing black. The inability to adjust a display to absolute black negatively affects its depth of field.
     

  • Cost
    Plasma is expensive. For that reason alone, plasma is not for everyone. But prices are coming down, as they do for most new technologies.
     

  • More susceptible to burn-in
    It's not a good medium on which to display a company logo for two or three hours at a time. But with the appropriate precautions, and in some situations a screen saver, you should not expect problems.
     

  • Resolution restrictions
    Plasma is subject to the same type of resolution problems as LCD or DLP projectors. You'll get the best images when the resolution of your source matches the "true" resolution of the monitor. But, as with LCD, the monitors will incorporate compression or expansion circuitry to automatically resize other resolution sources to match their native resolution, and most people will be very happy with the result. Still, if sharpness is critical for your application and you'll be using a variety of computer sources, you may be better off with a CRT-based unit.

 

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