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GLOSSARY

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A  B  C  D  F  H  K  L  M  N  O  P  R  S  T  U  V  W  X  Z  

   A

Anamorphic Lens

An anamorphic lens is a lens that has different optical magnification along mutually perpendicular radii. This provides the ability to project a source image of one aspect ratio, such as 4:3, into a different aspect ratio, such as 16:9, by using different magnifications for the horizontal and the vertical dimensions of the projected image.


ANSI

Acronym for American National Standards Institute; coordinates the development of U.S. voluntary standards in the public and private sectors. ANSI has established the standard followed by projector manufacturers for measuring lumen brightness.


Aspect Ratio

The ratio of height to width of a frame or screen. The aspect ratio for video is 3:4. Other aspect rations are 1:1, 16:9


   B

Bezel

The frame or face of a device, such as, a projector grill, or CRT or LCD display frame.


Brightness

The factor that makes darkness go away, measured in lumens on a projector.


BrilliantColor Technology

A technology developed by Texas Instruments for its DLP projectors that produces six channels of color including red, green, blue, cyan, magenta, and yellow; thereby, allowing an increase in the color gamut.


Bulb

A light source commonly mistaken for the light source within a projector. Bulbs power incandescent room lighting. Lamps power projectors.


Burn-In

Image distortion where phosphors are discolored at a differing rates in a display device such as a plasma, CRT or SED TV. Usually caused by displaying a static image for extended periods. Screensavers are used to prevent burn-in on CRTs and plasma displays use a periodic dynamic single pixel shift of the image to avoid burn-in.


   C

Closed Caption

Closed caption (CC) superimposes a transcript of the audio portion of a video program over the program image. Its primary use is to provide people that are deaf or hard of hearing the opportunity to read a transcript of the audio as it is being played. Closed Caption is also helpful for people learning to read or learning a foreign language. Closed Caption can also be used to display text unrelated to the program being viewed, such as weather or news.


Color Saturation

Measure of color purity. Highly saturated colors emit a very narrow band of wavelengths of light instead of the broader spectrum of frequencies emitted from mixed colors. A display with good saturation capability will look vibrant.


Color Wheel

Rotating wheel with 3 or more translucent color filters used to display sequential color on single imager light valve based projection devices. The imager reflects or transmits the color component of a given image when the wheel’s corresponding color filter is affecting the light passing through to the lens. A 1X wheel cycles through all colors in 1/60th of a second.


Compatibility

Relates to the video and computer signal formats the projector is capable of displaying.


Composite Video

Most common form of analog video signal.


Contrast Ratio

The ratio between white and black. The larger the contrast ratio the greater the ability of a video device to show subtle color details and tolerate ambient room light. There are two industry methods used: 1) Full On/Off contrast measures the ratio of the light output of an all white image (full on) and the light output of an all black (full off) image. 2) ANSI contrast is measured with a pattern of 16 alternating black and white rectangles. The average light output from the white rectangles is divided by the average light output of the black rectangles to determine the ANSI contrast ratio. When comparing the contrast ratio of video devices make sure you are comparing the same type of contrast. Full On/Off contrast will always be a larger number than ANSI contrast for the same video device.


   D

Digital Video

A signal in computer data form, which creates images and sound.


Dimensions

The physical size, length, width and height of a projector, measured in inches.


Distribution Amplifier

An amplifier used to maintain a clean noise free signal to a projector or flat panel device over significant distances. Even with good heavily shielded cables, range of video and computer signals is limited to a few dozen feet before noticeable degradation. In ceiling mount situations, where the wiring may pass along side or across electrical conduits, a distribution amp may be needed with shorter distances. Many distribution amps can also split the signal into 2 or more amplified signals for driving multiple projectors or flat panels.


DLP

Acronym for Digital Light Processing, a data projection technology developed by Texas Instruments using a microprocessor to display bright, colorful images in fully lit rooms. Used primarily in portable and ultra-portable projectors, the DLP chip is the size of a postage stamp and contains millions of microscopic mirrors - one for each pixel - that flip on an axis, reflecting light through a color wheel to create an image.


DMD

Digital Micromirror Device. Name of the actual imaging chip used in a Texas Instruments DLP projection systems.


DVI

Digital Visual Interface. DVI is a standard that defines the digital interface between digital devices such as projectors, flatscreens and personal computers. For devices that support DVI, a digital-to-digital connection can be made that eliminates the conversion to analog and thereby delivers an unblemished image. It can also carry an analog signal and comes as DVI-I (integrated - analog and digital), DVI-D (digital only) and DVI-A (analog only). Dual link DVI connections add additional resolution capabilities. Digital cable lengths should not exceed 15 feet.


   F

Focus

A point at which rays of light converge. It is adjusted to clarify a blurry image.


   H

HDMI

HDMI (High Definition Multimedia Interface) is an uncompressed, all-digital audio/video interface that supports audio/video sources such as a set-top box, DVD player, A/V receiver, and video monitors such as a digital projector or digital television (DTV). HDMI is backward compatiable with DVI 1.0 specification and supports HDCP. HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio, and interactive controls on a single cable. It transmits all ATSC (Advanced Television Systems Committe) HDTV standards and supports 8-channel digital audio. First product releases using HDMI occurred in 2003.


HDTV

Acronym for High Definition Television, a high-resolution television standard using an 1125-line broadcast signal.


High Gain Screen

screen that uses one of many methods to collect light and reflect it back to the audience, which dramatically increases the brightness of the image over a white wall or semi-matte screen. Technologies used include curved screens, special metal foil screens (some polarized), and certain glass bead screens. High gain screens achieve higher brightness by directing more of the reflected light towards the center of the screen.


   K

Keystone/ Keystoning

The distortion of an uncorrected image projected on a wall or screen, typically shown to be wider across the top and shorter across the bottom, resembling a keystone of an arch.


   L

Lamp

The bright source of a projector partially responsible for the sharpness and clarity of an image.


LAN

Acronym for Local Area Network; (See also network).


LCD

Acronym for Liquid Crystal Display. Liquid crystals exist in an intermediate state between liquid and solid, and realign under electrical stimulation. Exceptionally slim and lightweight, they are ideal in word processor, computer and TV displays.


LCoS

Liquid Crystal on Silicon. Type of LCD panel that reflects light as opposed to blocking it. Usually offers a comparatively high fill rate creating a smooth image but generally has difficulty giving a high contrast ratio.


LED

Light Emitting Diode. A light generating technology that uses a semiconductor diode that emits monochromatic (single color) light when charged. LEDs are used in remote controls that are used to control electronic devices such as large displays. They are also used in pocket projectors as a light source, large outdoor electonic displays, and as indicators on electoronic devices such as power supplies and cameras.


Long Throw Lens

A long throw lens allows greater distance between the projector and the screen while being able to maintain the image size and brightness of a shorter throw lens for any given projector. Depending on the room, a long throw lens may be required due to mounting constraints nearer the projected image.


Lumen

A unit of measurement of the amount of visible light energy that comes from a light source and is perceived by the eye.


   M

Microdisplay

Sometimes referred to with the acronym 'MD' as in MD-RPTV. Refers to projection-based displays using a chip-based imager. Examples are DLP, LCD and LCoS/D-ILA.


Mini Jack

An audio connection interface common on personal cassette/CD players, computers and some projectors.


Multimedia

A computer technology that enables the presentation of information using graphics, sound, animation and text.


   N

Network

Connecting two or more computers and/or networkable devices for data sharing or remote control of devices.


NTSC

Acronym for National Television Systems Committee, the television standard for the United States, administered by the Federal Communications Committee (FCC). NTSC is 525 lines of resolution transferred at a rate of 30 frames per second.


   O

OEM

Original Equipment Manufacturer. A company that gathers components from other manufacturers and sells under their own name. An OEM version of a product is supported by the seller, not the actual manufacturer.


Ohm

Measure of electrical resistance, inductance or reactance.


   P

PAL

Acronym for Phase Alternate Line, the standard color system used throughout Western Europe except in France. PAL-M is the standard system in Brazil. It uses an interlaced format with 25 frames per second and 625 lines per screen.


Pin

The connector used in computer/projector cables. Cables are often identified by the number of pins they contain. A typical computer video cable has 15 pins and is called a 15-pin video cable.


Pixel

Short for picture element. The smallest graphic unit that can be displayed on the screen, usually a single-colored dot.


Power Down

A modern term for turning something off.


   R

Rainbow Effect

An image anomaly that can be seen by a small percentage of people when viewing a single chip DLPTM front or rear projection system. The anomaly appears as a color breakup at the edge of objects when the eye transitions rapidly between light and dark areas of the image. The problem is characteristic of sequential color systems with low refresh rates.


RCA

Also called Composite, RCA jacks are a common connection interface for audio and video sources.


Remote

A small handheld device separate from the projector, which contains projector controls such as volume, brightness, etc.


Resolution

The visual quality of a computer screen or projected image measured by the number of pixels wide by the number of pixels high. More pixels per unit of area produce a higher resolution giving more detail in the display of an image.


RGB

Acronym for red, green, blue. Represents the chrominance information in a video signal, the primary colors from which all other colors can be construed.


RoHS

The Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Directive (2011/65/EU) was transposed into UK law on 2 January 2013. As such, the content of these web pages are currently being reviewed and updated as appropriate


   S

S-Video

A video connection interface. Also a generic name for Y/C, applied to S-VHS or Beta E. This format offers a higher quality than composite video, but a lower quality than component video.


Screen Gain

As it applies to projectors, gain is the measurement of a projection screen’s light reflectance with unity gain being one. A high gain screen will reflect more light along a narrower path than lower gain screen. Screen gains under one use a gray screen to absorb ambient light to help maintain contrast ratios.


Screendoor Effect

An image distortion caused by digital imagers with a low fill rate. Looks like the picture is seen through a screen door with thin vertical and horizontal black lines and is commonly noticeable on lower resolution LCD displays. An LCD display fitted with a microlens array helps reduce this problem.


SECAM

Acronym for Systeme En Couleur Avec Memoire (sequential color with memory); the color TV system used in France and throughout the Eastern Block republics.


SRS WoW

The Sound Retrieval System (SRS) is a patented psychoacoustic 3D audio processing technology originally invented by Arnold Klayman in the early 1980s. The SRS technology applies head-related transfer functions (HRTFs) to create an immersive 3D soundfield using only two speakers, widening the "sweet spot," creating a more spacious sense of ambience, and producing strong localization cues for discrete instruments within an audio mix. SRS is not a Dolby matrix surround decoder but works with normal stereo recordings. Initially Hughes Aircraft, for whom Klayman was doing acoustic consulting at the time, offered a standalone SRS audio processor, as well as licensing the technology to Sony and Thomson (RCA) for inclusion in their products. In the early 1990s, Hughes sold off its non-aerospace-related holdings, and a group of entrepreneurs formed SRS Labs to acquire the SRS technology.


Stereo

An audio playback technology that divides sound into two or more sources, creating a more realistic sound.


Subwoofer

An audio device dedicated to replicating the lowest, deepest sounds ascertainable by the human ear.


SVGA

A video resolution equating to 800 x 600 pixels in size; acronym for Super Video Graphics Display.


   T

TFT

Acronym for Thin Film Transistor, a technology used with LCD screens also known as Active Matrix.


Throw Distance

Throw distance is the measurement from the projector's lens to the screen. A projector with a zoom lens will have a range of throw distances for any given image size, while a projector without a zoom lens will only be able to project one image size at a given distance from the screen. In Projector Central's articles, throw distance is normally quoted for a 100" diagonal screen.


Tweeter

A small speaker designed for high frequency reproduction.


   U

UHP

Acronym for Ultra High Performance and/or Ultra High Efficiency, a term typically used with metal halide lamps that power ultra-bright projectors.


Uniform Brightness

The lack of brighter or dimmer areas of a projected image across a lighted surface.


USB

Acronym for Universal Serial Bus, a peripheral connection interface for low-speed devices notable for its hot-swapability.


   V

Ventilation

Airflow through a projector's internals for the purpose of cooling the lamp or light source.


VGA

A video resolution equating to 640x480 pixels in size; acronym for Video Graphics Array.


   W

Watt

A unit of power. Volts multiplied by amperage equals watts.


Weight

The weight of the projector minus power cord, bag and other optional accessories.


Wi-Fi

Wi-Fi is Wireless Fidelity, and is a type of wireless network used to connect digital devices without the need for cables. It is mostly used for wireless broadband access and inexpensive consumer wireless antennas are available at electronics stores. There are four specifications currently in the family: 802.11, 802.11a, 802.11b, and 802.11g.


   X

XGA

A video resolution equating to 1024 x 768 pixels in size; acronym for Extended Graphics Array.


   Z

Zoom

To make an area of an image larger.


Zoom Ratio

The ratio between the smallest and largest image a lens can projector from a fixed distance. For example, a 1.4:1 zoom lens ratio means that a 10 foot image without zoom would be a 14 foot image with full zoom. Conversely, a 10 foot diagonal image at 15 feet with no zoom would still be a 10 image at 21 feet at maximum zoom (15 x 1.4 = 21 feet). A zoom lens is "not as bright" as a fixed lens, and the higher the ratio, the less light output.