User`s manual

doc-3331-2 OverView cDG67-DL (August 2003) 3-5
3.3 Screen
The image is generated in the screen . It consists of the optical screen and a frame with which the
screen is exactly mounted onto the structure.
Fresnel Lens
The screen consists of a Fresnel lens and a Front Element Screen. The Fresnel lens deflects the
light coming from the projection lens system such that it falls perpendicularly onto the front ele-
ment screen.
Front Element
The front element screen guarantees that the light is distributed horizontally and vertically, while
maintaining a high contrast.
Texture of Surface
The surface of the screen has a special non-glare texture. This texture minimizes the direct reflec-
tion of the light of the surrounding and contributes also to the high contrast of the screen.
3.4 Princip le of DMD Projection Technology
For a one-chip projection system, the DMD is sequentially illuminated with the three primary col-
ors, red, green, and blue (RGB)
Figure 3-3
principle of a single-chip DLP projection system
A condenser lens collects the light, which is imaged onto the surface of a transmissive color wheel.
A second lens collects the light that passes through the color wheel and evenly illuminates the sur-
face of the DMD. Depending on the rotational state of the mirror (+12 or -12 degrees), the light is
directed either into the pupil of the projection lens (on) or away from the pupil of the projection
lens (off). The projection lens has two functions: (1) to collect the light from each on-state mirror,
and (2) to project an enlarged image of the mirror surface to a projection screen.
The example shows a color wheel with three segments red, green, and blue. It is also possible that
the segments for the primaries exist twice (RGBRGB), or that a white segment is added (RGBW).