dB — decibel — A unit used to express relative difference in power or intensity, usually between two acoustic or electric signals, equal to ten times the common logarithm of the ratio of the two levels.
Diagonal Screen — A method of measuring the size of a screen or a projected image. It measures from one corner to the opposite corner. A 9FT high, 12FT wide, screen has a diagonal of 15FT. This document assumes that the diagonal dimensions are for the traditional 4:3 ratio of a computer image as per the example above.
DLP® — Digital Light Processing™ — Reflective display technology developed by Texas Instruments, using small manipulated mirrors. Light passes through a color filter is sent to the DLP mirrors which arrange the RGB colors into a picture projected onto screen, also known as DMD.
DMD — Digital
Focal Length — The distance from the surface of a lens to its focal point.
Frequency — It is the rate of repetition in cycles per seconds of electrical signals. Measured in Hz (Hertz).
Hz (Hertz) — Unit of frequency.
Keystone Correction — Device that will correct an image of the distortion (usually a
Maximum Distance — The distance from a screen the projector can be to cast an image that is usable (bright enough) in a fully darkened room.
Maximum Image Size — The largest image a projector can throw in a darkened room. This is usually limited by focal range of the optics.
Minimum Distance — The closest position that a projector can focus an image onto a screen.
NTSC — National Television Standards Committee. North American standard for video and broadcasting, with a video format of 525 lines at 30 frames per second.
PAL — Phase Alternating Line. A European broadcast standard for video and broadcasting, with a video format of 625 lines at 25 frames per second.
Reverse Image — Feature that allows you to flip the image horizontally. When used in a normal forward projection environment text, graphics, etc. are backwards. Reverse image is used for rear projection.
RGB — Red, Green, Blue — typically used to describe a monitor that requires separate signals for each of the three colors.
Glossary
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