rear-projection TV


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rear-projection TV

An earlier large-screen TV set that has employed one of several technologies for generating the image. Rear-projection TVs (RPTVs) were developed to extend the size of a TV screen beyond the CRT TV, which for all practical purposes maxed out at 36". Introduced in the 1970s and very popular throughout the 1980s and 1990s, at the end of 2012, Mitsubishi, the only remaining vendor of RPTVs, ceased production of its DLP-based 82" and 92" sets (for a novel rear-projection device, see SPUD).

Although RPTVs were still bulky, no CRT TV could have been built with as large a screen. Using mirrors and lenses, the projected image was flipped up and over rather than straight toward the screen.

The Largest Screen for the Money
Early rear-projection systems suffered from a narrow viewing angle. Because the screen itself was a lens, standing up or walking off to the side dramatically changed the brightness. Although newer sets had wider viewing angles and were the only large-screen TVs available for many years, they were nowhere near as visually dazzling as the flat TVs that followed. See viewing angle.

Rear Vs. Front Projection
RPTVs were a fixed size, whereas front projectors can change their screen dimension by changing the external screen and repositioning the unit (see front-projection TV). See microdisplay, plasma, LCD and video/TV history.


Rear Screen Vs. Front Screen
Rear-projection systems are self-contained, whereas front-projection systems use a separate screen several feet from the unit.







It All Started With CRT Guns
The first RPTVs used three 7" CRTs to generate red, green and blue light. This 64" set was two feet deep, but a CRT TV that size would have been too costly to build and too big to transport.


It All Started With CRT Guns
The first RPTVs used three 7" CRTs to generate red, green and blue light. This 64" set was two feet deep, but a CRT TV that size would have been too costly to build and too big to transport.








Liquid Crystal Microdisplays (MicroLCDs)
RPTVs were less bulky when microdisplays replaced the CRTs. Light was beamed through tiny red, green and blue LCD panels approximately 1.5" diagonal, and each one was modulated with the pixel pattern for that color. Lenses enlarged the image. The Liquid Crystal over Silicon (LCoS) method reflected light back to color filters. See LCoS.







Digital Light Processing (DLP)
DLP reflects light from tiny pixel-sized mirrors. Also used in today's front-projection units, the technology uses either a single chip and color wheel (this example) or three chips with their own sets of mirrors and color filters. See DLP.
References in periodicals archive ?
Sony will gradually reduce production of plasma TVs at its Ichinomiya factory in Aichi Prefecture and instead increase the production of LCD and rear-projection TVs, the sources said.
Rear-Projection TVs use cathode ray tubes (CRTs), focusing lenses, a mirror and a display screen to create images on the screen.
The new technologies are principally liquid-crystal displays (LCDs), and plasma displays, as well as microdisplay-based rear-projection TVs (RPTV).
Overcoming two common objections to rear-projection TVs -- bulk and price -- the new Gateway 56-inch DLP(TM) or Digital Light Processing(TM) TV packs the benefits of rear projection into a package that's one-third the size of traditional rear projection TVs.
Falling prices for electronics - especially large-screen direct-view as well as rear-projection TVs - have spurred consumer interest at all income levels.
IDC used a separate testing laboratory, Imaging Science Foundation, to conduct real-world tests of high-definition plasma, LCD, and Microdisplay rear-projection TVs to measure their color uniformity, viewing angles, black levels, contrast ratios and image retention.
In a major advance, microdisplay-based rear-projection TVs currently dominate the high-end home theater market," said Tamaryn Pratt of market research firm Quixel Research.
HP Pavilion microdisplay televisions, the company's first line of microdisplay rear-projection TVs, are designed for consumers who want to enjoy HDTV programs in full HD-resolution and DVD movies on a large screen.