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Encyclopedia > 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 focussed and enlarged onto a screen using a lens kept in front of the CRT face. Most modern CRT projectors are colour 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 focussed by their lenses to achieve the overall picture on the screen. A video projector takes a video signal and projects the corresponding image on a screen. ... The cathode ray tube or CRT, invented by Karl Ferdinand Braun, is the display device used in most computer displays, video monitors, televisions and oscilloscopes. ... Color is an important part of the visual arts. ... Red is a color at the lowest frequencies of light discernible by the human eye. ... Look up Green in Wiktionary, the free dictionary Green is a color seen commonly in nature. ... For other uses, see Blue (disambiguation) Blue (from Old High German blao shining) is one of the three primary additive colors; blue light has the shortest wavelength range (about 420-490 nm) of the three primary colors. ...

  • Advantages:
    • Long CRT life, typically that of a normal television picture tube.
    • Can achieve good to very good colour resolution, brightness and picture size.
    • Once set-up, minimal maintenance is required, unlike projectors that use lamps.
    • Superior black level - black is actually black and not dark grey.
    • 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.
  • Disadvantages:
    • Tends to be bulky and heavy (and non-portable) due to the CRTs.
    • Low maximum brightness levels - the room has to be completely dark and eyes of viewers coming from a daylight environment have to adapt to the darkness for a minute or two before image details can be seen.
    • Suffers from uneven colour mixing, since it is done by projecting the inividual lines (made on the CRTs) on to the screen. The result is that the picture optimised for the central area of the screen tends to split into the individual colours towards the edges. Sophisticated circuitry is required to compensate for this.
    • Focussing is not even, again due to the way the image is projected and requires sophisticated circuitry to compensate for.
    • Requires more time to set up and adjust for a good overall image.
    • Costlier than other types of projectors due to the complex circuitry required to control and synchronise the three CRTs to achieve optimum picture quality. (Although it is easier to get good deals on used equipment than with other types of projectors)

Interlacing is a method of displaying images on a raster-scanned display device, such as a cathode ray tube (CRT). ... Deinterlacing the process of converting interlaced images of video into non-interlaced form. ...

See also

Barco Barco is an acronym that originally stood for Belgian American Radio COmpany. ...


  Results from FactBites:
 
Projector - Wikipedia, the free encyclopedia (136 words)
Projectors are used for displaying an image on a projection screen or similar surface for the view of an audience.
Ceiling projector or cloud searchlight, used to measure the base of cloud heights
Projector was also the name of a version control system developed by Apple Computer as part of the Macintosh Programmer's Workshop software development system.
CRT projector - Wikipedia, the free encyclopedia (461 words)
A CRT projector is a video projector that uses a small, high-brightness CRT (or picture tube) as the image generating element.
Most modern CRT projectors are colour 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.
  More results at FactBites »


 

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