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Television Technology
| Q. |
What is DLP (Digital Light Processing)? |
| A. |
A projection TV technology developed by Texas Instruments, based on their Digital Micro mirror Device (DMD) microchip. Each DMD chip has hundreds of thousands of tiny swiveling mirrors which are used to create the image. The popular HD2 DLP chip has an array of 1280 by 720 mirrors, where each mirror represents a single pixel to provide 720p resolution. DLP technology is used in both front- and rear-projection systems. Some new models use a new process called "wobbulation" to produce a 1080P resolution.
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| Q. |
What is LCD (Liquid Crystal Display)? |
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Liquid Crystal Display technology is one of the methods used to create flat-panel TVs. Light isn't created by the liquid crystals; a light source (bulb) behind the panel shines light through the display. The display consists of two polarizing transparent panels and a liquid crystal solution sandwiched in between. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal acts like a shutter, either allowing light to pass through or blocking the light. The pattern of transparent and dark crystals forms the image.
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| Q. |
What is LCoS (Liquid Crystal on Silicon)? |
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A projection TV display technology that sandwiches a layer of liquid crystal between a cover glass and a highly reflective, mirror-like surface patterned with pixels that sits on top of a silicon chip. These layers form a micro display that can be used in rear-projection and front-projection TVs. Manufacturers use different names for their LCoS-based technologies. JVC uses D-ILA™ or HD-ILA™, while Sony uses SXRD™. These both produce a true 1080P resolution.
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| Q. |
What is Plasma? |
| A. |
Gas-plasma technology is one of the methods used to create flat-panel TVs. Besides enabling thin, lightweight TVs that can be hung on the wall, plasma offers other advantages. The display consists of two transparent glass panels with a thin layer of pixels sandwiched in between (think of this layer as containing around one million tiny fluorescent bulbs — the pixels). Each pixel is composed of three gas-filled cells or sub-pixels (one each for red, green and blue). A grid of tiny electrodes applies an electric current to the individual cells, causing the gas to ionize. This ionized gas (plasma) emits high-frequency UV rays which stimulate the cells' phosphors, causing them to glow, which creates the TV image.
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| Q. |
What is Rear-projection TV? |
| A. |
Typically referred to as "big-screen" TVs, these large-cabinet TVs generally have built-in screens measuring at least 40". Up until a few years ago, all rear-projection TVs used three CRTs to create images. Using CRTs resulted in cabinets that were relatively heavy and bulky — nearly always designed as floor standing TVs. Newer digital micro display rear-projection technologies, like DLP, LCD, and LCoS, make possible the more compact, lightweight "tabletop" big-screen TVs.
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| Q. |
What is Resolution? |
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The sharpness of a video image, signal or display, generally described either in terms of "lines of resolution," or pixels. The resolution you see depends on two factors: the resolution of your display and the resolution of the video signal.
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| Q. |
What is the differences between Vertical Resolution and Horizontal Resolution? |
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Vertical resolution: The number of horizontal lines (or pixels) that can be resolved from the top of an image to the bottom. (Think of hundreds of horizontal lines or dots stacked on top of one another.) The vertical resolution of the analog NTSC TV standard is 525 lines. But, some lines are used to carry other data like closed-captioning text, test signals, etc., so we end up with about 480 lines in the final image, regardless of the source. So, all of the typical NTSC sources — VHS VCRs, cable and over-the-air broadcast TV (analog), non-HD digital satellite TV, DVD players, camcorders, etc. — have vertical resolution of 480 lines. DTV (Digital Television) signals have vertical resolution that ranges from 480 lines for SDTV, to 720 or 1080 lines for true HDTV.
Horizontal resolution: The number of vertical lines (or pixels) that can be resolved from one side of an image to the other. Horizontal resolution is a trickier concept, because while the vertical resolution of all analog (NTSC) video sources is the same (480 lines), the horizontal resolution varies according to the source. Some examples for typical sources: VHS VCRs (240 lines), analog TV broadcasts (330 lines), non-HDTV digital satellite TV (up to 380 lines), and DVD players (540 lines). DTV signals have horizontal resolution that ranges from 640 lines for SDTV, to 1280 lines (for 720p HDTV) or 1920 lines (for 1080i HDTV).
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