Wednesday, June 3, 2009

Non-print equipment & services: Video data projectors

A data/video projector is a device that allows you to project the screen image from a computer, or a video from a VCR, or DVD onto a larger screen for group viewing. In the past an LCD (liquid crystal display) panel that fit on an overhead projector was often used to project computer images. These required that the room be practically dark. Newer projectors are self-contained systems that allow use in lighted room conditions.

Large screen video projection technology has been in existence since the early 1970’s. Its original application were the display of video inside Boeing passenger planes and projection of the ground/sky horizon outside the cockpit of fighter aircraft training simulators.

Currently there are at least three types of data/video projectors: LCD (liquid crystal display) based models, DLP (digital light processing) models and LCOS (liquid on silicon) models.

LCD projectors: Use a lamp to shine through coloured liquid crystal panels and then through a lens. Each dot (pixel) is capable of turning on and off to create a colour. The more pixels per panel, the higher the resolution and the better the image.
  • Offers the best colour reproduction.
  • Currently LCD projectors are the most popular choice no matter the application

DLP projectors: A propriety technology developed by Texas Instruments. A DLP (digital light processing) chip is a reflective surface of thousands of tiny movable mirrors which reflect light from the lamp through a lens onto the screen.

  • Most compact, some weigh only 3 pounds.

LCOS projectors: Hybrid between LCD and DLP. Most popular version of LCOS termed D-ILA (direct drive image light amplifier).

  • Currently largest and heaviest of the three types.
  • Smoothest video image.

When used as a data projector, “always attach the cable from your computer to the projector first. Then turn on the projector before turning on your computer. In most cases the computer will detect the projector as an external monitor and it will set itself up automatically. By doing things in this order you will avoid having to figure out the proper keystrokes required on most laptops to get things working.”

United Visual. Does it matter which I turn on first, my projector or my computer?

Additional information
*Broida, Rick. “Should you choose a DLP or LCD projector?” District Administration, Sep 2003, Vol 39 issue 9, p52, 2/3 p. [required reading]

Collins, Christian. “Rapid Advances Fuel Race for Projection Engine Dominance.” Pro AV Magazine, August 2003. not currently available online.

Powell, Evan. The Great Technology War: LCD Vs. DLP

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