Appendix
C
Display Systems
C-3
Interface
A device that accepts an input signal for display
by the projector.
Interlace
A method used by video tape players and some
computers to double the vertical resolution
without increasing the horizontal line rate. If the
resulting frame rate is too low, the image may
flicker depending on the image content.
Keypad
A device which allows the user to control
projector settings and operation. There are four
different keypad types which may be used with
the projector: built-in, IR remote, wired remote,
and presenter's. For more information about
these keypads, refer to the keypads entry in
section 3.2, Projector Basics.
Keystone
A distortion of the image which occurs when the
top and bottom borders of the image are not
equal in length. Side borders slant in or out,
producing a keystone shaped image.
Learn Screen
An ACON function which stores screen position
data in memory for future reference. Learn
Screen is usually performed only once per
projector installation. If the ACON Locator
Assembly or screen is moved (i.e., the projector
installation changes to ceiling mount), the Learn
Screen function must be repeated.
Linearity
The reproduction of the horizontal and vertical
size of characters and/or shapes over the entire
screen.
Line of Best Viewing
When light from a projector is incident on a
screen, the light reflects from the screen such that
the angle of reflection equals the angle of
incidence. The Line of Best Viewing is along the
line of reflection.
Locator Assembly
The Locator Assembly, situated on the front of
projectors which include the ACON automatic
convergence feature, is the "eye" of the ACON
system. It includes a photosensor/lens
component which mechanically scans the
projected display at each convergence point while
sensing relative positions of each projected color.
Loopthrough (Loopthru)
The method of feeding a series of high
impedance inputs from a single video source with
a coaxial transmission line in such a manner that
the line is terminated with its characteristic
impedance at the last input on the line.
Lumen
The amount of visible light emitted by a light
source is measured in lumens.
Lux
The amount of visible light per square meter
incident on a surface.
1 lux = 1 lumen/square meter = 0.093 foot-
candles
Menu
A list of options which are displayed on the
screen for selection by the user.
NTSC Video
A video output format of some video tape and
disk players. There are two types of NTSC
(National Television Standards Committee) video:
NTSC 3.58 and NTSC 4.43. NTSC 3.58 is used
primarily in North America and Japan. NTSC
4.43 is less commonly used.
Optical Screen
A type of rear-projection screen which re-directs
light through the screen to increase image
brightness in front of the screen. Screen gain is
usually greater than 1 but audience viewing
angles are reduced.
PAL Video
A video output format of some video tape and
disk players (used primarily in Europe, China and
some South American and African countries). All
PAL (Phase Alternating Line) video is a 50 Hz
standard with 768 x 576 resolutions.
Pincushion
A distortion of the image which occurs when the
borders are concave or convex.
Pixel (Picture Element)
The smallest discernable element of a computer
generated image.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
