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Display technology
Digital video equipment in an edit suiteSee also: Liquid crystal display
television
Thanks to the advances in display technology, there are now several kinds of
video displays used in modern TV sets:
CRT(Cathode Ray Tube): The most common screens are direct-view CRTs for up to 40
inch (100 cm) (in 4:3 ratio) and 46 inch (115 cm) (in 16:9 ratio) diagonals.
These are the least expensive, and are a refined technology that can still
provide the best overall picture quality value. As they do not have a fixed
native resolution, they are capable of displaying sources with different
resolutions at the best possible image quality. The frame rate or refresh rate
of a typical NTSC format CRT TV is 29.97 Hz, and for the PAL format, 25 Hz, both
are scanned with two fields per frame in an interlaced fashion. A typical NTSC
broadcast signal's visible portion has an equivalent resolution of about 640x480
pixels. It actually could be slightly higher than that, but the Vertical
Blanking Interval (VBI), allows other signals to be carried along with the
broadcast. High lead content.
Rear projection: Most very large screen TVs (to 100 inches [254 cm] or more) use
projection technology. Three types of projection systems are used in projection
TVs: CRT-based, LCD-based, and DLP (reflective micromirror chip) -based.
Projection television has been commercially available since the 1970s, but at
that time could not match the image sharpness of the CRT; current models are
vastly improved, and offer a cost-effective large-screen display.
A variation is a video projector, using similar technology, which projects onto
a screen.
A modern Philips LCD TVFlat panel (LCD or plasma): Modern advances have brought
flat panels to TV that use active matrix LCD or plasma display technology. Flat
panel LCDs and plasma displays are as little as 1 inch thick and can be hung on
a wall like a picture or put over a pedestal. Some models can also be used as
computer monitors.
LED technology has become one of the choices for outdoor video and stadium uses,
since the advent of ultra high brightness LEDs and driver circuits. LEDs enable
scalable ultra-large flat panel video displays that other existing technologies
may never be able to match in performance.
Each has its pros and cons. Flat panel LCD display can have narrow viewing
angles and so may not suit a home environment. Rear projection screens do not
perform well in natural daylight or well lit rooms and so are best suited to
dark viewing areas. A complete run down of the pros and cons of each is
available here.
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