[geeks] Screw question

[Bill Bradford]

On Mon, Dec 12, 2005 at 07:58:48AM -0500, Phil Stracchino wrote:
> "spinning wheel"?

http://en.wikipedia.org/wiki/Dlp

"In a projector with a single DMD chip, colors are produced by placing a 
color wheel between the lamp and the DMD where it is reflected out through 
the optics. The color wheel is usually divided into four sectors: the primary 
colors: red, green, and blue, and an additional clear section to boost 
brightness. Since the clear sector reduces color saturation, in some models 
it may be effectively disabled, and in others it is omitted altogether.

The DMD chip is synchronized with the rotating motion of the color wheel so 
that the green component is displayed on the DMD when the green section of 
the color wheel is in front of the lamp. The same is true for the red and 
blue sections. The red, green, and blue images are thus displayed sequentially
at a sufficiently high rate that the observer sees the composite "full color" 
image. In early models, this was one rotation per frame. Later models spin 
the wheel at twice the frame rate, and some also repeat the color pattern 
twice around the wheel, meaning the sequence may be repeated up to four times 
per frame."

Looks like three-chip DLP systems don't have this issue; I think they're
relatively new.

-- 
Bill Bradford 
Houston, Texas