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Redirected from: RPTV
Definition: rear-projection TV
An earlier large-screen TV that employed several technologies to generate the image. Rear-projection TVs (RPTVs) were developed to extend the size of the CRT TV, which for practical purposes maxed out at 36" (larger units weighed several hundred pounds).
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 the quality of today's LED and OLED TVs. See viewing angle, microdisplay, plasma, LED TV, OLED and video/TV history.
Rear Screen vs. Front Screen
It Started With Three CRT Guns
Liquid Crystal Microdisplays (MicroLCDs)
Digital Light Processing (DLP)
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 the quality of today's LED and OLED TVs. See viewing angle, microdisplay, plasma, LED TV, OLED and video/TV history.
Rear-projection systems were self-contained, whereas front-projection systems require a separate screen. Like regular TVs, RPTVs had a fixed screen size, whereas front projectors can change their screen dimension by changing the external screen and repositioning the unit (see front-projection TV).
The first RPTVs used three 7" CRTs to generate red, green and blue light. This 64" set was two feet deep. A CRT TV with a 64" screen would have been too costly and too big to transport.
RPTVs were less bulky when microdisplays replaced the CRTs. Light was beamed through tiny red, green and blue LCD panels approximately 1.5" diagonal, each modulated with the pixel pattern for that color. Lenses enlarged the image. Another method was Liquid Crystal over Silicon (see LCoS).
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.