Handbook for Sound Engineers

1586 Chapter 44

• When the display is turned on and the chip begins
  transmitting the signal, the mirrors flip back and forth
  thousands of times per second.


• Mirrors in the on position reflect the light through a
  projection lens and onto the screen. The longer a
  mirror is in the on position, the lighter the pixel it
  creates. Mirrors that are off for longer periods create
  darker pixels, and mirrors that are always off create
  black pixels. By varying the length of time that the
  mirrors point toward the projection lens, the DMD
  creates up to 1024 shades of gray.


• The gray pixels combine on the screen to create a
  progressive, fully digital monochrome image.


• To add color to the picture, the single chip DLP
  system uses a color wheel, Fig.44-5.


• The color wheel is a transparent, spinning wheel with
  red, green, and blue. The light passing through each
  section turns red, gree, or blue.


• The system’s processor synchronizes the spinning of
  the wheel with the action of the mirrors. Together, the
  DMD and the color wheel can create 256 shades of
  each primary color.


• Each pixel of light on the screen is red, gree, or blue
  at any given moment. The colors are then blended to
  create the desired colors of the image.


• With DLP projectors, a small number of people
  might experience a rainbow effect when watching a
  DLP projection, especially when they change their
  focus from one part of the image to another, seeing
  the individual component colors.


• This happens only in DLP systems that use a
  segmented color wheel, not in systems that use one
  DLP chip for each primary color.
  
  
  • A number of home theater systems use color wheels
    with additional segments, two segments of each
    color, or sequential color recapture (primary colors
    arranged in a spiral instead of in segments) in order
    to reduce the appearance of the rainbow effect.
  
  
  • New BrilliantColor™ color wheel technology reduces
    the appearance of the rainbow effect. In the newer
    DMD generations, a light-eating dark metal coat is
    applied to the interior of each chip, preventing stray
    light from traveling to the screen when mirrors are
    switched off. This improvement increases contrast
    ratios from 1200:1 to >2000:1 and higher.
  
  
  • Increased mirror tilt angle (from ±10 to ±12q), brings
    20% more light to the screen for greater brightness.
  
  
  • Double data rate technology allows a DMD chip to
    tilt toward or away from its light source twice as fast,
    allowing more accurate grayscale reproduction.
  
  
  
  

44.8.3.3 New DLP BrilliantColor™ Color Wheel

Technology

Historically, most display devices would render a scene

using the three primary colors, red, green, and blue.

This limits available colors that can be displayed,

making it difficult to display brilliant yellows,

magentas, and cyans that are commonly found in

natural scenes.

BrilliantColor™ technology adds yellow, cyan, and

magenta colors to the color wheel, maintaining bright

whites while providing deeper red, green, and blue

colors.

BrilliantColor™ provides brightness increases in

nonprimary colors and boosts overall color intensity.

BrilliantColor™ provides flexibility in color wheel

design allowing for bright, large color gamuts and

differentiation from OEMs.

Figure 44-4. Three chip DLP projection TV.

Figure 44-5. Single chip DLP technology.