Da-Lite: Educational Materials

Ambient light - All light in a viewing room produced by sources other than the screen.

Aspect ratio - The numeric relationship between a screen's height and width. This ratio is often defined by the selected projection medium. Hence, NTSC Video (U.S. television) has an aspect ratio of 3:4.

Bend Angle - The angle through which a projected light ray must be diverted from its original path to reach a viewer's eyes.

Borders - The black portion surrounding the viewing area of a screen.

Brightness - A viewer's subjective response to luminance.

Contrast ratio - The numeric relationship between the brightest and the darkest portions of a display expressed in foot-lamberts as a ratio of Max:Min.

CRT - Cathode Ray Tube. Same technology used in TV and computer monitors.

DLP Technology - This technology is based on the Digital Micromirror Device™ (DMD™) which uses over 500,000 microscopic mirrors on the SVGA chip to reflect images on screen.

Dolby Pro Logic^TM - An audio technology utilizing a center channel (fifth loudspeaker) designed to primarily position dialogue and other information at the center of a viewing area.

Drop - The area between the top of the viewing area and the bottom of the screen housing.

Foot-candle - The fundamental unit of illumination representing the light intensity over a 1 square foot surface which is 1 foot away from a standard candle.

Footlambert - A unit of luminance equivalent to 1 lumen per square foot.

Gain - A measurement usually made perpendicular to screen center of the luminance transmitted by the screen, divided by the luminance radiating from the projector.

HDTV - Acronym for High Definition Television

Keystone - The distortion of the projected image when the screen is not perpendicular with the center line of the projected image.

LCD - Liquid Crystal Display. Commonly used in digitized projection.

Lenticular - Screen surface comprised of a geometric embossing pattern. The shape of the pattern affects view\angle performance and reflection of ambient light.

Luminance - The measured brightness of a screen, expressed in foot-lamberts.

Projection axis - The direction of an imaginary line extending from the center of the projection lens through the screen's center.

SVGA - Super Video Graphic Array. Common computer screen resolution. (800 x 600)

Throw distance - The length of the projection beam necessary for a particular projector to produce an image of a specified size.

VGA - Video Graphic Array. Common computer screen resolution. (640 x 480)

Viewing angle - The angle from a specified viewing position to the center of the screen. It is usually measured on the horizontal or on the vertical axis.