A Glossary of Projector Terms and Definitions – Shedding Some Light on the Subject
The world of projectors – a very wide subject, encompassing many aspects of technology. It can be so confusing. If you’ve seen the latest multimedia projectors, then you’ll understand. Or maybe you won’t. Understanding the technology behind these complex machines can be tough. There are so many terms to learn. So that’s why we’ve compiled this glossary of projector terms and definitions – to help you through the jargon and the technical terms. Here we go.
Ambience refers to a room’s level of lighting, such as daylight, artificial light, etc. The higher the ambience, the brighter the projector needs to be to produce a viewable image.
An analog video signal uses a variable voltage to equal the pixel value, as opposed to digital pulses.
ANSI stands for the American National Standards Institute. The power of the illumination and the contrast ratio on a projector are always preceded by ANSI because they’ve officially approved this format of lighting.
- ANSI lumens
ANSI lumens refers to the degree of brightness illuminated in a projector’s display, measured in “candles”.
- Aspect ratio
The aspect ratio is the ratio of width to height of a projected picture.
- Auto balance
Auto balance is a system that detects errors in color balance in black and white areas of the picture, and automatically adjusts the black and white levels of both the read and blue signals as needed for correction.
- Back room projector
A back room projector has a “long-throw” lens that can be used from the far back of a room. This is an available option in many projectors.
A backlit remote control or control panel has illuminated buttons and controls, great for operating a projector in a dark room.
- Built-in loop through
A built-in loop through in a projector allows another screen or projector to be connected, displaying the same signal.
The chrominance of a picture refers to its color saturation and hue.
- Color banding
Color banding occurs when the transition of color from one to another isn’t smooth.
- Color temperature
Color temperature refers to the amount of “whiteness” of a light source. Metal halide lamps have much higher color temperatures than halogen lights and bulbs.
- Component video
Component video delivers the best quality video image possible.
Compression is used to convert one resolution to another. For example, a projector that has SVGA resolution may accept XGA resolution and compress it to SVGA, resulting in a clearer picture.
- Contrast ratio
The contrast ratio refers to the ratio of darkness to brightness.
Dichroic is a mirror or lens in a projector that reflects or refracts wavelengths of light, thus separating the white light into red, green and blue.
- Digital signal
A digital signal is strung together in infinite variations at rapid speeds to transmit computer information.
- Distribution amplifier
A distribution amplifier allows one source signal to be amplified and distributed over significant distances, through multiple outputs.
- DLP (digital light processing)
DLP is the display technology developed by Texas Instruments which uses mirrors to display an image.
- DVI (digital visual interface)
DVI refers to the digital interface between projectors and PCs. A projector that has DVI can send a digital-to-digital connection, without converting to analog, thereby delivering a clear image.
The fader on a projector is a control that allows you to balance the sound between the internal and external speakers.
- FM-based remote
An FM-based remote control can be used in a large room because it has a long range and no line-of-sight requirements.
The focus on a projector defines the minimum and maximum projection distances.
- Foot lamberts
Foot lamberts are a measurement of reflected light off a surface. It’s determined by taking the light output of your projector and dividing it by the square footage of your screen, them multiplying by the screen gain.
Halogen projector bulbs are used in most low- and medium-priced projectors. They last about 40 hours.
- HDMI (high-definition multimedia interface)
HDMI is a standard for video interfacing, with a bandwidth of up to 5 gigabytes, which means it can easily support all HDTV standards.
Interface refers to the connection between different elements of a system, which converts the signal so it can be recognized by both elements.
Automatic keystoning is a projector feature that creates a uniform image top to bottom by correcting the image if it’s projected onto the screen on an angle.
- LCD (liquid crystal display)
LCD is a display technology that uses electric current to align crystals in a special liquid. The rod-shaped crystals are contained between two parallel transparent electrodes, and when current is applied, they change their orientation, creating a darker area.
A lumen is a measurement of light. The higher the lumen count, the brighter the projection.
Luminance refers to the color intensity of an image.
- Metal halide
Metal halide light bulbs give off a much brighter image and last longer than halogen. High-end, and some medium projectors now use metal halide bulbs.
- Mouse emulator
Most portable projector remote controls have a mouse emulator which allows the user to move around during the presentation while still having control of the computer source.
Multiplex allows you to split an image into several panels on a single screen.
NTSC, or the National Television Standards Committee, is the video transmission system used in America.
- PAL (phase alternating line)
PAL is the video transmission system used in the Western Europe, Asia, Australia and certain countries in South America and the Far East.
A pixel is a small dot that represents a single element of a display.
Polysilicon is a material used in the manufacture of the LCD screen in high-end multimedia projectors. It gives a better contrast ratio and faster response time than TFT LCD screens.
A projector is a device that integrates a light source, optics system, electronics and displays, thus projecting an image from a computer or video onto a surface for large image viewing.
QXGA is the resolution of 2048 x 1536 pixels.
- Rainbow effect
On DLP projectors, the rainbow effect is created by the inability of the DLP color wheels to refresh pixels fast enough, resulting in some color separation on the edges of fast-moving objects.
Resolution is defined by the number of dots a display uses to create an image, expressed in pixels. For example VGA is 640 x 480, and SVGA is 1280 x 1024. The higher the resolution, the sharper the image.
- Scan converter
A scan converter in a projector converts a digital signal from a computer to a video signal, thus allowing it to be shown on a video projector or TV monitor.
- SECAM (sequential coulcur a memoire)
SECAM is the video transmission standard in France, Russia Eastern Europe and some countries in Africa.
- Short throw lens
A short throw lens is designed to project the largest possible image from a short distance.
- SVGA (super VGA)
SVGA is the standard 800 x 600 computer video signal in IBM-compatible PCs.
- TFT (thin film transfer)
TFT allows for more efficient use of the light source that creates the image from LCD panels.
- Three-panel LCD
Some projectors used 3 LCD panels, one for each primary color, which enhances color reproduction and gives a richer image.
- Throw distance
The throw distance is the distance from the center of a projector lens to the center of the screen onto which it’s projecting.
UXGA is the resolution of 1600 x 1200 pixels.
- VGA (video graphics array)
VGA is the standard resolution of 640 x 480 used for computer video signals in IBM-compatible PCs.
WSXGA is a class of SXGA resolution, 1920 x 1600 horizontal pixels, and 1080 x 900 vertical pixels.
- Zoom lens
A zoom lens is a feature on higher-end projectors that allows adjustment of focal length instead of moving the projector.
So those are the terms you’ll need to know if you want to gain a good understanding of projectors. And you will need to know these terms if you’re shopping for a multimedia projector. They have many features that can help you give a great multimedia presentation. And, if you do that, you’ll be shedding your own light on your subjects – and winning their business in the process. So take your new-found knowledge – and convert it into wisdom – and then success!
About The Author
Gareth Marples is a successful freelance writer providing valuable tips and advice for consumers purchasing multimedia home theater systems, as well as overhead & slide projectors and, for the camera buff, Canon digital cameras & reviews. His numerous articles offer moneysaving tips and valuable insight on typically confusing topics.
This "Glossary of Projector Terms and Definitions" reprinted with permission.
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