Electronic Projection System Glossary of Terms

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Active Matrix LCD

A type of liquid crystal display (LCD) technology where each pixel is actively controlled by a diode or a transistor, allowing greater color and contrast quality than passive matrix LCD. See also Liquid Crystal Display and Passive Matrix LCD.

ANSI

American National Standards Institute. Devised the ANSI Lumens scale of projector brightness.

ANSI Lumens

A measurement of the overall projector brightness, representing the average value of 9 points on the projected screen image on a scale devised by the American National Standards Institute (ANSI). See also Lumens.

Aspect Ratio

The ratio between the width and height of the output (monitor, LCD projection panel, overhead or slide).

CGA (Color Graphics Adapter)

A card that enables an IBM® PC and XT to handle graphics and color. Resolution is 640 x 200 pixels with a 16-color maximum. This standard is now almost obsolete.

Composite Video

A video signal combining all the color and timing components of an image into a single input line.

Compression Mode

A method of displaying images in a reduced size format. A compressed image usually has part of the image information discarded. The result is a projected image that has light and dark lines and text characters with thick and thin line widths.

Contrast Ratio

The ratio of the brightest and darkest images a display can reproduce.

Convergence

The alignment of the red, green, and blue components of a video image signal on a projected display system. Improper convergence can cause color fringes or "ghosts" in the projected image.

Display Size

The diagonal length of the LCD display area. Typical laptop display sizes are 8.4" to 12.1".

Distribution Amplifier

A device that amplifies and transmits a video or computer signal using shielded coaxial cable, especially over more than a few dozen feet, to prevent signal degradation or electrical interference. Can also send a signal to multiple projector devices.

DLP (Digital Light Processing)

A display technology by Texas Instruments that is based on the digital micromirror device (DMD), and projects extremely bright, high-quality, high-definition images.

DSTN (Double Super Twist Nematic)

A passive matrix LCD technology where two separate LCD plates are combined to form a single panel for improved image quality and contrast. See also STN (Single Twist Nematic), TSTN (Triple Super Twist Nematic), and Passive Matrix LCD.

EGA (Enhanced Graphics Array)

Enhanced Graphics Array. The second generation of the CGA card giving IBM PCs, XTs and ATs greater resolution (640 x 350). Now almost obsolete.

FCC Class B Certified for home use

A device classified as FCC Class B Certified for home use does not interfere with other devices, and it can handle interference from other devices.

Hz (Hertz)

Increment used to express the frequency of an electrical signal or event in cycles per second. See also KHz (KiloHertz, 1,000 cycles per second) and MHz (MegaHertz, 1 million cycles per second).

Image Compression

Compresses higher resolution images into 640 x 480.

Interlaced

Every other line is scanned during each total vertical (full) screen refresh.

IR (Infra-Red)

A type of wireless transmission via infra-red light waves, often used for remote control devices.

KHz (KiloHertz)

1,000 cycles per second. The frequency of an electrical signal or event. See also Hertz (Hz) and MegaHertz (MHz).

LCD (Liquid Crystal Display)

A glass panel display that electronically controls the light passing it. See also Active Matrix LCD and Passive Matrix LCD.

Long Throw Lens

Enables a projector to decrease its image size over the standard lens at the same throw distance. With a long throw distance the user is able to project a smaller image so that it will fit on the screen.

Lumen

The unit of illumination on a surface. One lumen is the light of one candle power on each square foot of a surface of a sphere at a radius of one foot from the light source. See also ANSI Lumens.

MegaHertz (MHz)

1 million cycles per second. The frequency of an electrical signal or event. See also Hertz (Hz) and KiloHertz (KHz).

Non-Interlaced

Each line is scanned during each total vertical (full) screen refresh. Reduces image flicker and associated eyestrain. See also Interlaced.

NTSC (National Television Standards Committee)

The standard for broadcast color television and other video equipment signal in the US, Canada, and other countries. Established in 1953. 525 lines/60 Hz.

Palette

The number of colors available to create an image. The use of a standardized palette in a presentation allows the user to create a consistent look.

PAL (Phase Alternate Line)

The phase of the color carrier alternates from line to line. Used extensively in Western Europe. 625 lines/50Hz.

Panel

The same as liquid crystal display (LCD).

Passive Matrix

An older form of liquid crystal display (LCD) technology that controlled pixel processing for entire areas of the screen (instead of individual pixels, as in active matrix LCD), with reduced color, contrast, and speed. See also Active Matrix LCD.

Pixel

Abbreviated term for picture element. The smallest element of display, consisting of a single dot or group of three dots (red, green and blue). Total pixels are usually expressed in horizontal x vertical dimensions (e.g., 640 x 480).

Polysilicon LCD

The most current liquid crystal display (LCD) technology, combining separate LCD layers of red, green, and blue light for increased color and contrast.

Polysilicon TFT (Thin Film Transistor)

A type of LCD technology that allows more light at high temperatures through the LCD.

Refresh Rate

The number of times the screen image is "painted" or refreshed per second, expressed in Hz.

Resolution

The number and concentration of dots or pixels in a given portion of the image (i.e., 800 x 600). A higher resolution reproduces more image detail and a broader range of light and dark.

Response Time

The time it takes for a pixel to turn on and off. Typically measured in milliseconds, an active-matrix LCD projection panel's response time is fast enough to display full-motion video and rapid mouse cursor movements.

RGB (Red, Green, Blue)

The basic signal components of the color video system.

SECAM

Sequential Couleur Avec Memorie. The color television standard developed in France. SECAM is used mostly in France and Eastern European countries. 625 lines/50Hz.

Serial Port

A data I/O port linking the computer to other computers or devices. Also referred to as RS-232C or COM port.

Short Throw Lens

Enables a projector to increase its image size over the standard lens at the same throw distance. The user can create larger images at closer distances.

STN (Super Twist Nematic)

A passive matrix liquid crystal display (LCD) technology used in some monitors to twist combined light rays for improved screen quality. See also DSTN (Double Super Twist Nematic), TSTN (Triple Super Twist Nematic), and Passive Matrix LCD.

SVGA (Super VGA)

A graphic of 800 x 600. This standard has versions with different vertical frequencies.

S-Video (S-VHS)

A video signal that separates luminance (Y) and chrominance (C) signals.

SXGA (Super XGA)

A graphic of 1280 x 1024. 

Thin Film Transistor (TFT)

The active matrix liquid crystal display (LCD) technology most common in LCD panels and monitors. It places the controller of the panel directly on the surface of the glass, producing higher quality screen images.

Transmitivity

The percentage of light transmitted from the stage of the overhead projector that reaches the screen at a given distance. Typically, LCD projection panels are able to use less than 10% of the total light available. Also known as transmissivity.

TSTN (Triple Super Twist Nematic)

A passive matrix liquid crystal display (LCD) technology used in some monitors to twist three combined LCD light rays for improved screen quality. See also DSTN (Double Super Twist Nematic), STN (Super Twist Nematic), and Passive Matrix LCD.

VESA (Video Electronics Standards Association)

A non-profit group of companies organized to define and improve computer graphics standards.

VESA Standard

A set of display specifications agreed upon by the VESA organization, usually referred to by resolution and vertical refresh rate. VESA standards usually achieve a higher display quality by increasing the resolution (e.g., 1024 x 768) while maintaining a high vertical refresh rate (e.g., 72 Hz) to reduce flicker.

VGA (Video Graphics Array)

The standard interface for IBM PS/2®. The only analog graphics card IBM has used (others handle digital information). 720 x 400 resolution in text mode, 640 x 480 resolution in graphics mode.

Video

The capability to project images from a VCR, DVD, laser disc player, or a computer with a CD-ROM drive.

VirtualMouse Remote Control

3M's lightweight remote control offers all of the functionality of a computer-compatible mouse.

Wi-Fi

Wi-Fi is the popular term for a high-frequency  wireless local area network (WLAN). The Wi-Fi technology is rapidly gaining acceptance in many companies as an alternative to a wired LAN. The 802.11b (Wi-Fi) operates in the 2.4 GHz range offering data speeds up to 11 megabits per second.

XGA (Extended Graphics Adapter)

IBM's graphics standard that includes VGA and extended resolution up to 1024 x 768.

Y-Cable

A cable splitting the monitor signal to work simultaneously with both a monitor and LCD panel.