CATHODE RAY TUBE (CRT) PROJECTORS
Currently there are three types of projector on the market: Cathode Ray Tube (CRT), Digital Light Processing (DLP), and Liquid Crystal Display (LCD). This Projector Source Canada article will focus specifically on CRT projectors so you can be informed of exactly what Cathode Ray Tube projectors are, how these CRT projectors display images, what situations they are most often used in, and the future of CRT technology.
We will also provide information on the advantages and disadvantages of CRT projectors allowing you to make an informed decision when deciding what type of projector is right for your presentation application.
What is Cathode Ray Tube technology?
A cathode ray tube is a dedicated vacuum tube where an electron beam comes into contact with a phosphorescent surface. Cathode ray tube technology is a display technique first used in 1897.
CRT gained popularity in 1931 when it was first implemented for use in a television to generate images. This technology was then later adapted for use in projectors.
How CRT projector technology produces an image
The technical specifications for CRT technology are primarily composed of cathode ray tubes, lenses, and video processing circuitry. As the name suggests, Cathode Ray Tube projectors utilize tiny, bright cathode ray tubes to generate the image to be projected.
The majority of modern CRT projectors contain three tubes, one dedicated to each primary colour (red, blue and green). When receiving a video signal each primary colour is processed and then forwarded it to the respective tube. Each tube has a lens positioned in front of it that is then used to focus and enlarge the image, generating the overall picture.
Advantages of CRT projectors
The tubes used in CRT projectors have an extremely long lifespan that can maintain a consistent level of brightness for over 10,000 hours. DLP and LCD projectors on the other hand require their light sources to be replaced at least every 2,000 hours to ensure an optimal level of brightness
No rainbow effect
The "rainbow effect" (the effect where objects on screen briefly appear to have a rainbow trail) that can affect single chip DLP projectors is nonexistent in CRT projectors.
Better black images
The shades of blacks that CRT projectors are capable of rendering are far superior to what DLP and LCD are capable of projecting.
CRT projectors are capable out outputting extremely high resolutions (reaching 1920 x 1200) that can be projected while maintaining precisely rendered colours. Although some projectors boast far greater resolutions ranging up to 3200 x 2560, the consequence is that the quality of the image is greatly degraded.
Variable resolution and refresh rate
The ability to have a variable resolution and refresh rate, a feature lacking in DLP and LCD projectors, allows for interlaced images to be played without the need for imperfect deinteleracing techniques.
Disadvantages of CRT projectors
Big and bulky means reduced portability
The physical bulkiness of a CRT projector means that it is far heavier and larger than its DLP or LCD competitors. One CRT projectors can take up as much space as an old fashioned 20-inch CRT television. This makes the opportunity for portability extremely limited if you wish to move the projector or set it up in different places.
Lower levels of brightness
The brightness levels achievable with CRT projectors are not typically as high as those seen in LCD and DLP projectors. Consequently it is far more important to use CRT projectors in a darkened room.
Set up times
The amount of time it takes to set up a CRT projector is far more time consuming and complex when compared to the other types of projectors on the market.
High price tags
The cost of CRT projector suitable is far higher than another type of projectors with similar specifications.
Professional tuning requires
The constant requirement to tune CRT projectors to ensure that the best possible image is projected is costly as well as a hassle. If the three projection tubes (red, blue, and green) are not properly aligned, however, then the colours can become mixed and colour halos can become apparent.
Replacing parts is costly
Should one of the three cathode ray colour tubes break or stop working correctly it can be a hassle to replace, and are expensive.
Possible applications for CRT projectors
While CRT projectors are suitable for most projector situations such as in a class room or in a home theatre, the fact remains that now both LCD and DLP projectors can offer better performance, such as sharper colours or better contrast images at a lower cost.
Due to their size CRT projectors are best suited to fixed installation situation. If you already own a CRT projector the only situation in which it cannot provide an adequate degree of adaptability is when presenters need to use projectors in many different locations and have to constantly transport the projector.
The future of CRT projectors
There are approximately only three manufacturers in the world still producing CRT projectors. For most consumers they are not a viable option to consider since they are extremely difficult to find in consumer electronic shops.
Projectors using LCD or DLP technology are currently the hottest thing to buy and are gradually replacing CRT projectors. CRT projectors are still used in certain industry and commercial environments and since they were the original projector and have been around for such a long time, there are still fairly large numbers of CRT projectors installed in homes today.
We hope you enjoyed this article by Projector Source Canada. For more information, or to purchase a display and projector for your business or home, visit us online at http://www.projectorsourcecanada.ca
or contact us at 1-800-821-3021.
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