CRT projector

A CRT projector is a video projector that uses a small, high-brightness CRT (or picture tube) as the image generating element. The image is then focused and enlarged onto a screen using a lens kept in front of the CRT face. Most modern CRT projectors are color and have three separate CRTs (instead of a single, colour CRT), and their own lenses to achieve colour images. The red, green and blue portions of the incoming video signal are processed and sent to the respective CRTs whose images are focused by their lenses to achieve the overall picture on the screen. Various designs have made it to production, including the "direct" CRT-lens design, and the Schmidt-CRT, which employed a phosphor screen that illuminates a perforated spherical mirror, all within an evacuated "tube."

Advantages and disadvantages

Advantages

*Long service life, CRT tubes maintain good brightness to 10,000 hours. [cite web|url=http://www.curtpalme.com/CRTPrimer_4.shtm|title=Curt Palme CRT primer|work=Curt Palme.com]
*High end CRT projectors can precisely display images up to 1920 x 1200 [Barco Cine 9, Sony G90] [The Barco 912 claims an addressable resolution of 3200 x 2560 but with a bandwidth of 180 MHz it is unable to resolve this resolution with any clarity. cite web|url=http://www.barco.com/VirtualReality/en/products/product_specs.asp?element=885|title=Barco 912|work=barco.com] with accurate color reproduction. A few projectors can scan at even higher resolutions up to 3200 x 2560, although their ability to resolve fine detail at this resolution is greatly reduced.
*Superior black level compared to LCD and DLP based projectors.
*As with CRT monitors, the image resolution and the refresh rate are not fixed but variable within some limits. Interlaced material can be played directly, without need for imperfect deinterlacing mechanisms.
*CRT projectors do not show a Rainbow effect seen with single chip DLP projectors.

Disadvantages

* CRT projectors are both considerably larger and heavier than comparable LCD and DLP projectors [The [http://www.curtpalme.com/docs/SonyG70_Brochure.pdf Sony G70] weighs 83 kg and measures 0.36 x 0.7 x 0.95 m where as the [http://www.projectorcentral.com/panasonic_ae900.htm Panasonic AE-900] LCD based projector weighs 3.6 kg and measures 0.09 x 0.34 x 0.26 m]
*CRT projectors require far more time to set up and adjust than LCD and DLP based projectors
*Absolute ANSI brightness achieveable with CRT projectors is lower than with comparable LCD/DLP projectors.
*Low-end or poorly tuned CRT projectors may suffer from color divergence.

ee also

* LCD projector
* DLP
* Barco
* List of CRT video projectors

References

External links

* [http://www.curtpalme.com/CRTPrimer.htm CRT Projector Primer/FAQ] Find out why CRT Projectors are still used in home theaters where image quality is paramount.
* [http://www.curtpalme.com/TechTips.htm CRT Projector Manuals & Setup tips] Hundreds of manuals and pictures showing board level controls and adjustments for the most popular projector models including Barco, NEC, Electrohome, Sony, Ampro, Zenith, etc.
* [http://www.curtpalme.com/forum CRT Projector Discussion Forum] A forum to ask CRT projector questions from other enthusiasts and technicians.