Projector Display Technology Explained

DLP Display
DLP technology can be found in projectors from manufacturers such as  BenQ, InFocus and Optoma.

Digital Light Processing™ is the world's only all-digital display solution. DLP™ technology uses an optical semiconductor, known as the Digital Micromirror Device, or DMD chip to recreate source material. 
DLP Display with DMD
    Advantages of DLP
    • Less 'chicken wire' (or 'screen door') effect because pixels are much closer together. This doesn't make so much difference with data, but it produces smoother images for video.
Screen Door Effect A comparison of an LCD and DLP projection to illustrate the 'screen door' or 'chicken wire effect on LCD projections.
  • Higher contrast achievable.
  • DLP has sealed optics which makes them better for use in a dusty environment.
  • DLP projectors are generally more portable as fewer components are required.

    Disadvantages of DLP
  • The 'rainbow' effect, appearing as a momentary flash of rainbow-like striping typically trailing the bright objects when looking from one side of the screen to the other, or when looking away from the projected image to an offscreen object. Only some people see this effect, or you can create it for yourself by moving your eyes very quickly across the screen. There are two types of DLP projector - the old ones had four segments on the colour wheel, the new ones have six or even seven and spin faster, which means less rainbow effect and more saturated colour.
  • The 'halo' effect (or 'light leakage'). It may bother some people using their projector for home cinema. Basically it's a grey band around the outside of the image, caused by stray light being bounced off the edges of the tiny mirrors on the DLP chip. It can be a distraction, but can be overcome by having a black border a few inches wide around the screen, so the halo falls on to the border. However the halo effect is less evident in the newer DLP chips such as the DDR chip
LCD Display

LCD technology is used by many manufacturer’s such as EpsonHitachi ,and NEC.

LCD (liquid crystal display) projectors contain three separate LCD glass panels, one for red, green, and blue components of the image signal being transferred to the projector. As the light passes through the LCD panels, individual pixels can be opened to allow light to pass or closed to block the light. This activity modulates the light and produces the image that is projected onto the screen.

3LCD Demo
    Advantages of LCD
    • LCD is generally more 'light efficient' than DLP (ie. the same wattage lamp in both an LCD and DLP would produce a brighter image through the LCD).

    • With 3LCD projectors, you get beautiful colour in clear, defined images - even in a bright room, and you get more than double the brightness on colour luminance, compared to non-3LCD projectors. What’s more, 3LCD projectors can project bright, vivid images with a low output lamp.
    • Hence, with a data signal, if you put a 1000 lumen LCD next to a 1200 lumen DLP and showed a colour image people would probably prefer the LCD.

    • LCD tends to produce a sharper image (ie. more precisely focused). This can actually be a bit of a disadvantage for video, where it makes the pixellation more obvious.

    Disadvantages of LCD
    • Generally more bulky, as there are more internal components.

    • 'Dead Pixels' - Pixels can become permanently on or permanently off, while this is barely noticeable with one dead pixel, if the projector develops multiple dead pixels it can be an irritation.

    • LCD panels can fail, and are very expensive to replace. DLP chips can also fail but as there are fewer parts in a DLP projector this is relatively rare.