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58 InFocus Corporation — Introduction Guide - DLP Multimedia Projector
Term Description
HDTV ready A television that supports 720p or 1080i or higher resolutions and does not have a built-in HDTV
tuner for off-air reception of HD signals from a special antenna. To view cable and satellite HDTV
programming, a cable set-top-box or satellite receiver is required.
Horizontal Lens
Shift
The purpose of Lens Shift is to eliminate keystoning and provide greater flexibility in the placement
of the projector relative to the screen. Lens shift may be a manual adjustment or motorized.
Horizontal lens shift typically allows the projector to be placed anywhere between right and left
edge of the projection screen and may also be used to geometrically align images when stacking
projectors. Vertical lens shift is also available on some projectors.
Horizontal
Resolution
Amount of pixels across an image, from left to right. A 1920 x 1080 HDTV has a horizontal resolution
of 1920 pixels.
Horizontal Scan
Rate
Period of time it takes to refresh an image on a screen, usually measured in Hertz (cycles per second).
Computer monitors typically have scan rates starting at 60Hz going to 85Hz.
Hue Hue or tint is the parameter of colour that allows us to distinguish between colours.
Hz Hertz. Also called cycles per second and in video displays is the rate at which an image is refreshed.
IEEE 1394 Also called FireWire or iLink. A serial bus which can address up to 63 devices, communicating at
up to 400Mbps but is limited to a cable length of 4.5 meters. Its content copy protection scheme is
called DTCP or 5C. Most DV camcorders have a IEEE 1394 port as well as D-VHS VCRs and some
set-top boxes for cable and satellite.
Infra-red
Remote
An infra-red (IR) remote control transmits in the spectrum of infra-red light, such as a television
remote. Unlike RF remotes, IR remotes must point at the receiver (line of sight) or reflect the IR from
the screen to the receiver.
Most projectors have an IR sensor in both the front and rear of the projector, whereas, flatpanels
generally have a single IR sensor in the front of the unit. When working at or near the maximum
distance, pointing right at the receiver will give better results.
Input Lag Input lag is the delay between your video source sending a frame to your projector and the projector
actually displaying that frame. This is a very important aspect of gaming, where an input lag of 40ms
or less is preferred.
Interactive
Projector
Interactive projectors became popular in 2010 and come in many variations. This technology
encompasses any solution that enables active participation by the user with the projected content,
rather than just the passive viewing of content.
Typically the presenter is allowed to interact with either the projected image, the projector, or in
some cases another device, using either an electronic pen, a mechanical pen or even a finger. These
Interactive Projectors essentially create an electronic whiteboard on any surface where the image
is projected allowing the presenter to interact with the projected image using a stylus that may be
electronic or mechanical.
Some interactive projectors allow user generated information to be captured and replayed, printed,
or copied with or without the original projected image.
Interlaced A process where a video image is delivered in two fields each containing half the video image rather
than a single frame that contains the entire image. The first field contains all the odd lines and the
second field contains all the even lines. For example, each 480i frame is made up of two fields of
263 and 262 lines of resolution and updated at 60Hz. 480 denotes the active picture area; however,
the total frame size is actually 525 lines. 480i and 1080i are interlaced signals whereas 720p is a
progressive signal where each video image is delivered in a single frame. Interlaced video was
introduced with the first televisions because of bandwidth limitations.
Glossary