Runco Video Xtreme VX-40d Owner's Operating Manual page 92

Appendix A: Glossary
Horizontal Frequency
Horizontal Offset
Hot Spot
Input
Input Signal
Interface
Interlace
Keypad
Keystone
Lamp Flicker
Linearity
Line of Best Viewing
Loopthrough (Loopthru)
Lumen
Luminance
Lux
The frequency at which scan lines are generated, which varies amongst sources. Also
➤
called horizontal scan rate or line rate.
The difference between the center of the projected image and the center of the projector
➤
lens. For clarity, offset is often expressed as the maximum amount of the image that can
be projected to one side of the lens center without degrading the image quality. Horizontal
offset ranges can be affected by the type of lens in use, and whether or not the image is
offset vertically at the same time.
A circular area of a screen where the image appears brighter than elsewhere on the
➤
screen. A hot spot appears along the line of sight and "moves" with the line of sight. High
gain screens and rear screens designed for slide or movie projection usually have a hot
spot.
A physical connection route for a source signal, described by a 2-digit number
➤
representing 1) its switcher/projector location and 2) its slot in the switcher/projector.
Signal sent from a source device to the projector.
➤
A device, such as the Serial Digital Input Module, that accepts an input signal for display
➤
by the projector.
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/field rate is too
low, the image may flicker depending on the image content.
A small push-button device for controlling most projector settings and operation. For more
➤
information, refer to 3.3, Using the Keypad.
A distortion of the image which occurs when the top and bottom borders of the image
➤
are unequal in length. Side borders both slant in or out, producing a "keyhole" shaped
image. It is caused when the screen and lens surface are not parallel, or by poor Keystone
adjustment.
As the lamp ages, the shape of two anodes may change from two points to a flattened
➤
state. When this occurs, the arc jumps across the gap from varying points. This is seen as
image flicker. Turning the Lamp Conditioning feature ON will pulse the lamp and gradually
"condition" the two anodes back to two points. Lamp Conditioning may take seconds,
minutes or hours to reach full effectiveness. NOTE: Lamp flicker can occur at any time in
the lamps life. The length of time, over which flicker may occur varies considerably and
unpredictably. This behavior is inherent in UHP lamps.
The reproduction of the horizontal and vertical size of characters and/or shapes over the
➤
entire screen.
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.
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.
The unit of measure for the amount of visible light emitted by a light source.
➤
The signal representing the measurable intensity (comparable to brightness) of an
➤
electronic image when the image is represented as separate chrominance and luminance.
Luminance also expresses the light intensity of a diffuse source as a function of its area;
measured in lumens or candles per square foot (1 lumen per square foot = 1 foot-lambert).
SMPTE RP 98 calls for a luminance of 12 to 22 foot-lamberts for theatre screens. See:
Foot-lambert.
The amount of visible light per square meter incident on a surface. 1 lux = 1 lumen/square
➤
meter = 0.093 foot-candles
92