Dataton WATCHOUT User's Guide

The following sections provide an overview of display technologies, with
special emphasis on aspects related to WATCHOUT.
CRT-based Displays
DLP Projectors
CRT projectors have the unique advantage of being able to reproduce a true
black. This is important in a totally dark environment, such as a planetarium,
when using the smooth edge-blending built into WATCHOUT. Without a true
black level, it is often impossible to avoid grey banding of the screen in the
overlap areas, due to the fact that there are two or more overlapping projectors
in this area.
CRT monitors and CRT-based video projectors and wall cubes may, however,
need extensive adjustment and calibration by a professional installer in order
to obtain acceptable color matching, convergence and image uniformity. Their
analog nature may also affect long-term stability.
DLP (Digital Light Processor) uses a microscopic mirror chip to modulate the
light. This display technology has the advantage of being 100% digital,
resulting in excellent, long-term image stability and reliability – particularly
when using a digital computer connection, such as DVI (see “DVI connector”
on page 29).
There are two primary kinds of DLP projectors; single chip and three chip. In a
single chip projector, one micromirror device handles all three primary colors
using a color wheel synchronized with the modulating mirrors. A three chip
projector uses a prism which splits the light into the three primary colors,
bouncing off three micromirror devices and combining the result to provide a
brighter image, suitable for very large displays.
The most significant problem with DLP projectors when used with WATCHOUT
is the lack of a true black level. The poor black produced by most DLP projec-
Chapter 2: System Requirements 17