What is 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

• Long service life, CRT tubes maintain good brightness to 10,000 hours.
• High end CRT projectors can precisely display images up to 1920 x 1200  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.
• 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.

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