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Copyright
2008
AV4Business Limited
AV4Business Limited
all rights reserved
Registered
in England: 4003990
VAT
Number: GB 817 0852 30
AV4Business
Limited
PO Box 123, Batley,
WF17
6ZZ
Phone: 0844 357 7820
Fax: 0844 357 6870
email: sales@av4business.com
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Glossary of Useful
Terms
A Active Matrix: The most common type of LCD, used in most laptops, and most LCD panels and projectors. A typical active matrix TFT display is a single panel of LCD glass that controls all three primary colours. TFT displays are noted for their quick response time and their ability to display full motion video and animations without image ghosting. Amorphous TFT: Material commonly used for Active TFT colour LCD arrays. Amorphous TFT LCD projectors generally utilise a single panel and are consequently less expensive and lighter than products based on polysilicon LCD’s ANSI Lumens: A standard for measuring light output, used for comparing projectors. Unfortunately, there are enough variables that the eye will often disagree radically with the ANSI rating. At best, ANSI lumens do fairly well comparing "apples" to "apples". If however one projector uses Halogen lamps and another metal-halide, the halogen projector will seem noticeably dimmer even if the two units rate the same. Other variables, including type of LCD technology (active matrix TFT, Poly-Si, passive), type of overall technology (LCD vs.DLP vs. CRT), contrast ratios, etc. all effect the end result. Aspect Ratio: The most popular aspect ratio is 4:3 (4 by 3). Early television and computer video formats are in a 4:3 aspect ratio, which means that the width of the image is 4/3 times the height. Examples: A 15 inch monitor is 12 inches wide by 9 inches high (9 x 4/3 = 12). A resolution of 640x480 is a 4:3 format (480 x 4/3 = 640). Other formats are 5:4 used by the 1280x1024 SXGA resolution, 16:9 is used by HDTV, and 3:2 for 35mm slides. B Back Room Projector: A projector with a "long-throw" lens designed to be used from the far back of the room, often in a projection booth, balcony, or back of an auditorium. Many typical projectors have third party lenses available for "long-throw" applications. Backlit: Refers to a remote control, or on projector control panel, that has buttons and controls that are illuminated. This is a major asset when using the projector in a darkened or semi-darkened room. Many projectors have backlit remote controls, while the number of projectors with backlit control panels is much smaller. Bandwidth: The number of cycles per second (Hertz) expressing the difference between the lower and upper limiting frequencies of a frequency band; also, the width of a band of frequencies. Built in loop through: The image being shown can be duplicated onto another projector or a monitor. Brightness: The attribute of visual perception in accordance with which an area appears to emit more or less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness.) C Carry-on Case: Refers to a projector with carrying case that fits into the overhead bin or under the passenger seat of an airline. A projector case that does not fit these conditions will need to be checked as luggage, and ride in the cargo area of the airline. Make sure you have a good hard case when checking a projector as luggage. Coated Optics: A variety of materials are put on to high quality lenses for several reasons. One of the key reasons is to minimize the amount of light reflected back to the lamp, and the amount of ambient light that mingles with the focused light leaving t he lens. Generally good coatings can add 15% or more to the lenses brightness. Other coatings are used for filtering colours. Composite Video Signal: The combined picture signal, including vertical and horizontal blanking and synchronizing signals. Compressed Resolution: Anytime a projector can accept a higher resolution signal and compress the data down to fit its true resolution. Quality of compressed images varies tremendously. Most but not all projectors offer compressed resolution for handling higher resolutions then their true resolution. Some use simple "line dropping" schemes while others achieve varying degrees of higher quality with different "intelligent" algorithms. Compressed SVGA: Unlike CRT based monitors, LCD and DLP projectors only have one "true" resolution. Most projectors out there are VGA (640x480) resolution. To project an 800x600 image to a VGA projector, the original 800x600 signal must be compressed down to VGA. This is done by interpolating the data, and trying to best display all the information with only two thirds of the pixels (307,000 vs. 480,000). The resulting image gives you the SVGA page size, but some sacrifice of image quality. For the vast majority of people with SVGA laptops or desktops, they will have more satisfying results, outputting VGA to a VGA projector. Compressed SXGA: Found on XGA projectors, compressed SXGA handling allows these projectors to handle up to 1280x1024 SXGA resolutions. Most owners of XGA projectors that use the compressed SXGA are workstation users (SUN, SGI, IBM, HP...) Compressed XGA: Found on SVGA projectors, compressed XGA handling allows these projectors to handle 1024x768 XGA resolutions. How good the compressed XGA is on a given model is a key factor in the decision process for most people choosing an SVGA projector. This is true as the market shifts from SVGA laptops to those with XGA screens. Contrast Ratio: The ratio between the whitest and blackest portions of an image. The larger the contrast ratio the greater the ability of a projector to show subtle colour details and tolerate extraneous room light. CRT: Cathode Ray Tube – the technology used for the screens of domestic television sets and desktop PC monitors. D Diagonal Screen: A method of measuring the size of a screen or a projected image. It measures from one corner to the opposite corner. A 9FT high, 12FT wide, screen has a diagonal of 15FT. Digital Light Processing (DLP): The commercial name for this technology from Texas Instruments (TI): The technology inside is often referred to as either "micro-mirrors", or DMD. It works this way, build a few hundred thousand tiny mirrors, and line them up in 800 rows of 600 mirrors each. Now attach a hinge to each of those 480,000 mirrors. Attach each of those 480,000 hinges to its own very tiny motor! Power each motor with electrostatic energy! The motors tilt their mirrors up to 20 degrees at incredible speeds. This allows the mirrors to modulate light from a lamp, and send the "modulated signal" out through a lens, on to a screen.
F
Focal Length: The distance from the surface of a lens to its focal point. Front Room Projector or Position: A unit that sits close to the screen, its short throw lens projects an image size that is about the same as the distance to the screen. Generally the unit might be as close as 3/4 the screen size or as far as 1.2 times image size.
H
Hard Wired Remote: Generally a remote control is wireless, and uses infra-red transmitter. There are situations where this is not practical: Large rooms where the speaker is 35 ft or more from the projector. Rear projection, where the screen will pass some signal, but normally has the presenter pretty much tied down. Also, the presenter has to point the remote "at" the projector which often means turning away from the audience. High Gain Screen: A screen that uses one of many methods to collect light and reflect it back to the audience, which dramatically increase 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. Prices and performance vary tremendously, but attention to the screen can make a big difference, particularly in "tough" environments such as trade shows.
I
Infra-red Remote: The traditional remote control, it transmits infra-red, like a television remote. Typical range is limited to 30 or 35 feet. Infra-red requires line of site or a bounce off a hard surface. Some projectors have an IR sensor in both the front and rear of the projector, which can help a bit. FM radio frequency and remote mousing systems, by comparison, have two distinct advantages, no line of sight requirement, and longer range. Invert Image: Invert image flips the image from top to bottom, to compensate for ceiling mounting a projector upside down. Projectors typically ceiling-mount upside down, because most have "keystone" correction built in to compensate for the distortion created by "pointing up" from the table to the screen.
K
Keystone Correction: Using optics design or other methods to apply a "negative" keystone to the image, which will partially cancel the effects of keystoning. If you aim a projector with keystone correction at a screen with the lens level with the middle of the screen, you will note that the image at the bottom is wider than at the top. When the projector is in normal position, pointing upward 10-25 degrees, the resulting image is fairly rectangular. Keystoning: Keystoning is caused when the projected image is not perpendicular to the screen, making the top and bottom of the image different lengths.
L
Laser Pointer: A small pen or cigar sized pointer, that contains a small battery powered laser, which can project a small, red (typically), high intensity beam of light that is immediately very visible on the screen. Excellent for pointing to objects or text, to make a point. LCD: Liquid Crystal Display – a display technology that works by controlling the opacity of individual cells by varying the electrical signal passed between them. Each individual pixel acts as a shutter to modulate light being passed through. It comes in many forms, sizes, and resolutions. Its primary purpose is to present a digital image for viewing. Long Throw Lens: A lens designed for projection from the back of a room, or rather the back of a long room. A typical long throw lens might have to be 50 to 100 FT back to project a 10FT diagonal image.
M
Maximum Distance: The distance from the screen that a projector can focus the image. Most of the time, it is the manufacturer's opinion of how far from a screen the projector can be to cast an image that is useable (bright enough) in a fully darkened room. Menu Driven: Refers to the type of controls on a projector. A typical menu driven system will first offer a menu of major categories such as Computer, Video, Audio, Display, Options. After selecting Computer, you will get another menu of choices with items like brightness, contrast, number of colours, colour balance, sync. Select one of those and you can then adjust it. Many projectors which are menu driven, also offer the most widely used functions in a non-menu fashion, such as separate buttons on the remote for volume, brightness, and contrast, as well as switching between channels/sources. Metal Halide Lamp: The type of lamp used in many medium and all high end portable projectors. These lamps typically have a "half-life" of 1000-2000 hours. That is they slowly lose intensity (brightness) as they are used, and at the "half-life" point, they are half as bright as when new. These lamps output a very "hot" temperature light, similar to mercury vapour lamps used in street lights. Their whites are "extremely" white (with slight bluish cast.) and make Halogen lamp's whites look very yellowish by comparison. Mid Room Projector: Designed to sit not too close or far from the screen, for a 10FT screen, typical placement is 12.5 to 25FT away. Most mid-room projectors have zoom lenses. Minimum Distance: The closest position that a projector can focus an image onto a screen.
N
NTSC: The United States broadcast standard for video and broadcasting.
O
OHP: The common abbreviation for overhead projector. Overhead Projector (OHP): A device consisting of a light source, a reflective platform, and a focusable lens assembly. An OHP is designed to project images from transparencies onto a screen.
P
PAL: A European and international broadcast standard for video and broadcasting. Polysilicon: An LCD panel material that offers better performance and colour contrast than the more common amorphous TFT and is currently featured in some top-of-the-line LCD projectors. Power Zoom: A zoom lens with the zoom in and out controlled by a motor, usually adjusted from the projector's control panel and also the remote control. Projector: A projector is a device that integrates a light source, optics system, electronics and display(s) for the purpose of projecting an image from a computer or video device onto a wall or screen for large image viewing. There are hundreds of products available in the market and they are differentiated by their resolution, performance and features. These devices attached to a computer or video device as you would connect a monitor.
Q
QXGA: QXGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. A QXGA display has 2048 horizontal pixels and 1536 vertical pixels giving a total display resolution of 3,145,728 individual pixels that are used to compose the image delivered by a projector.
R
Rear Screen Projection: Using an opaque screen, the projector is placed behind the screen, invisible to the audience. It projects onto the screen and the audience sees it on the other side. Good rear projection screens actually produce brighter images than some standard screens. So as not to waste space behind the screen, ideally a projector with a short throw lens is used. Since the projector can be placed even with the middle of the screen, without blocking anyone's view, keystoning is not a problem Resolution: The first specification to look for in selecting a projector is the resolution. The figure is given as horizontal pixels x vertical pixels. The standards are: VGA (640x480), SVGA (800x600), XGA (1024x768) and SXGA (1280x1024). Reverse Image: Reverse image is a feature found on most projectors which flips the image horizontally. When used in a normal forward projection environment text, graphics, etc, are backwards. Reverse image is used for rear projection. RGB: Red, Green, Blue; the normal type of monitor used with computers, examples of usage: RGB input or output often referred to as Computer input or output.
S
S-Video: A video transmission standard that uses a 4 pin mini-DIN connector to send video information on two signal wires called luminance(brightness, Y) and chrominance(colour, C). S-Video is also referred to as Y/C. A composite signal, typically found coming out of an RCA jack on the back of most VCRs has the Y and C information combined into one signal. The advantage of having luminance and chrominance separated is that a comb filter is not needed inside the video projector to separate the composite signal into the luminance and chrominance signals. A comb-filter can reduce the sharpness of your video image. SECAM: A French and international broadcast standard for video and broadcasting. Higher resolution than NTSC. Short Throw Lens: A lens designed to project the largest possible image from short distance. Most front room projectors use short throw lens. They are often required for rear projection, where the depth behind the screen is limited. SVGA: SVGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. An SVGA display has 800 horizontal pixels and 600 vertical pixels giving a total display resolution of 480,000 individual pixels that are used to compose the image delivered by a projector. SXGA: SXGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. An SXGA display has 1280 horizontal pixels and 1024 vertical pixels giving a total display resolution of 1,310,720 individual pixels that are used to compose the image delivered by a projector.
T
TFT: Thin Film Transistor Temperature: A method of measuring the "whiteness" of a light source. Metal halide lamps have very high temperatures compared to halogen or incandescent lights.
U
UXGA: UXGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. A UXGA display has 1600 horizontal pixels and 1200 vertical pixels giving a total display resolution of 1,920,000 individual pixels that are used to compose the image delivered by a projector.
V
VGA: VGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. A VGA display has 640 horizontal pixels and 480 vertical pixels giving a total display resolution of 307,200 individual pixels that are used to compose the image delivered by a projector.
X
XGA: XGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. An XGA display has 1020 horizontal pixels and 768 vertical pixels giving a total display resolution of 783,360 individual pixels that are used to compose the image delivered by a projector.
Z
Zoom Lens: A lens with a variable focal length providing the ability to adjust the size of the image on a screen by adjusting the zoom lens, instead of having to move the projector closer or further. Zoom Lens Ratio: Is 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. |
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What it
Means? Verified By Visa and MasterCard SecureCode give extra confidence when buying online. If your card issuer (Bank) subscribes to this then when you finally enter your card details and buy a box (directly from your bank) will pop up asking you for your password. (THIS IS NOT YOUR CHIP AND PIN NUMBER). If you have not registered a password before you will have to create one. This will ensure that, in future, you can have the confidence that a lost or stolen card cannot be used by anyone else. Like your pin number never reveal this password to anyone else and do not use one that anyone else can guess.
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