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Glossary of Terms
active matrix
See LCD. actual image size The size of the display on the screen is dependent upon the signals provided by the video card. The displayable diagonal measurement can vary, depending on how the graphics mode is generated and how the monitor responds to the characteristics of the video signal. aperture grille Aperture grille technology employs a series of thin, closely spaced vertical wires to isolate pixels horizontally. The pixels are separated vertically by the nature of the scan lines (beams) used to compose the image.
backlight
A technique used to make LCDs easier to read. bandwidth A measure of the display performance of a monitor. Expressed in MHz, bandwidth is the number of dots that can be displayed in a line per second. More strictly, it is the frequency response of the system between points where the signal level falls to a specified percentage of its maximum value (usually 50% or 75%). In principle, the greater the bandwidth, the better the monitor-although the quality of the picture tube is often the limiting factor affecting display performance, and for many standard monitors there is little point in increasing the bandwidth beyond a certain point. Typical bandwidths for monitors (Spring 2003) are as follows: VGA monitors: 18 MHz FGA+ monitors: 35 MHz CAD monitors: 100 MHz Bauart Component products can be Bauart certified by TUV for expected safety concerns, meaning evaluation to German and European Union standards for building in to other equipment. Typical component products are touchscreens, controllers, and kiosk or frame touchmonitors. brightness Light output measured at the faceplate of the CRT; typically measured in footlamberts (Fl). A minimum brightness level of 20 Fl when viewing a full-sized page is considered acceptable.
CD-ROM
Compact Disc Read-Only Memory. A CD-ROM is any compact disc that contains computer data. "ROM" means that you cannot save information onto these discs. These discs can hold huge amounts of data (up to 640 megabytes). If there is a large amount of data on a CD-ROM, then it is usually impractical to copy the data onto the hard disk; in this case, you must insert the disc into the drive whenever you want to use the data. CD-ROM may also refer to the drive used to read these discs. CE The CE (Conformite Europeene) marking on end products indicates compliance with all applicable directives. For information technology equipment (ITE), this typically means Low Voltage Directive 73/23/EEC (LVD), and the EMC Directive 89/336/EEC. Typical end products are desktop touchmonitors. Components typically do not carry the European Union's CE marking. Properly applied, they will comply with the LVD and EMC Directives. Typical component products are touchscreens, controllers, and kiosk touchmonitors. Refer to the product Declaration of Conformity (DOC) for test levels. contrast The ratio between the maximum and the minimum brightness of the display. contrast control A manual gain control for a monitor, affecting both luminance and contrast. C-Tick A trademark registered to the Australian Communications Authority, indicating compliance with the electromagnetic radiation emissions limits of Australia and New Zealand. CRT Cathode ray tube. Also known as picture tube or screen. A picture tube in a TV is also a CRT.
DDC
Display Data Channel. A VESA standard for communication between a monitor and a video adapter. Using DDC, a monitor can inform the video card about its properties, such as maximum resolution and color depth. The video card can then use this information to ensure that the user is presented with valid options for configuring the display. DDC2B VESA standard bi-directional digital data channel between the display and the host. The host initiates data transfer by reading the EDID from a memory location in the display. See also DDC and EDID. digital control Microprocessor-based digital control of picture parameters and video modes for complete control of picture settings and modes and instant recall of all settings at the push of a button. This very advanced feature allows the user to switch to any required mode at any instant without having to spend time readjusting the picture. dot pitch The distance between one phosphor dot (i.e. red, green, or blue) and the nearest phosphor dot of the same color in the line above or below. DPMS Display Power Management Signaling. A VESA standard that ensures that monitor and video card manufacturers produce power-saving products that work together. drive Any data storage device including CD-ROM drive, floppy disk drive, and hard disk drive.
EDID
Extended Display Identification Data. A VESA standard for data structures containing the display identity and the basic display specifications. electronic radiation standards International standards established to limit electromagnetic emissions from monitors. There are currently two important standards, both derived from regulations originally laid down by the Swedish authorities. See also MPRII, TCO95, and TCO99. EMC Electromagnetic compatibility. EMC requirements stipulate that a device shall not cause interference within itself or in other devices, or be susceptible to interference from other devices. The European Union was the first governing body to establish laws (CE) regarding immunity of devices from EMI. See also CE, EMI, and RFI. EMI Electromagnetic interference. This interference in the operation of a device is caused by incompatibility with ambient signals. Common sources of EMI include transmitters and receivers (radio, TV, cell phone), power mains (lightning, surges, brownouts), appliances, computer oscillators, and electrostatics. Many countries have established laws (such as FCC and CE) governing EMI source limits. See also CE, FCC Class A, FCC Class B, EMC, and RFI. ENERGY STAR® A voluntary partnership between the U.S. Department of Energy, the U.S. Environmental Protection Agency, product manufacturers, local utilities, and retailers. ENERGY STAR labeled products use less energy than other products. Partners help promote efficient products by labeling with the ENERGY STAR logo and educating consumers about the benefits of energy efficiency.
FCC Class A
A marking FOR OFFICE USE means the design has been tested for compliance with the U.S. Federal Communications Commission's (FCC) Part 15 Class A RF emissions limits, and is suitable for use in nonresidential settings. Industry Canada's RF emissions limits are identical to the FCC's. See also IC Class A. FCC Class B A marking FOR HOME OR OFFICE USE means the design has been tested for compliance with the U.S. Federal Communications Commission's (FCC) Part 15 Class B RF emissions limits, and is suitable for use in residential or nonresidential settings. Industry Canada's RF emissions limits are identical to FCC's. See also IC Class B. flat panel displays See LCD. flat square screen A screen that is flatter and squarer than the conventional CRT screen. The flatter outline reduces picture distortion and ambient reflections, and allows better use to be made of the screen area. flicker Condition of the display caused by the mismatch of vertical and horizontal refresh rates, when a phosphor's illumination begins to decay prior to being refreshed. The resulting "flicker" is particularly detectable with peripheral vision. Flicker can be eliminated by increasing the refresh rate to a value at or above 70 Hz. frequently asked questions A list of questions/answers provided by companies related to their products or Web site.
GS
A German certification, Geprhfte Sicherheit ("tested safety"). End products can be GS-certified by TUV for expected safety concerns, meaning they have been evaluated and have met German standards. Typical end products are desktop touchmonitors.
hard disk
A storage device inside a computer, generally designated as the C: drive. It cannot be seen without opening up the computer; however, usually a light on the front of a computer shows when the hard disk is being accessed. hertz The unit of frequency named after the physicist Heinrich Hertz (1857-1894). One hertz (Hz) is equal to one cycle/second. horizontal frequency The time it takes to scan each of the horizontal lines that make up the display; measured in kilohertz (kHz). Horizontal frequency is directly related to the vertical refresh rate, so that the greater the number of vertical lines, the higher the horizontal frequency required. horizontal scanning frequency The number of video lines written on the screen every second (from left to right); also called line frequency and expressed in kHz. The higher the horizontal scanning frequency, the higher the resolution and/or the refresh rate, which produces a more stable image, helping to reduce user fatigue and stress.
I2C bus: access bus
standard
A standard-protocol two-wire (clock and data) serial data bus. IC Class A A Class A compliance statement means the design has been tested for compliance with Industry Canada's ICES 03 Class A RF emissions limits, and is suitable for use in non-residential settings. Industry Canada's RF emissions limits are identical to the FCC's. See also FCC Class A. IC Class B A Class B compliance statement means the design has been tested for compliance with Industry Canada's ICES 03 Class B RF emissions limits, and is suitable for use in residential or nonresidential settings. Industry Canada's RF emissions limits are identical to the FCC's. See also FCC Class B. interlaced scanning mode A scheme that takes two passes to paint an on-screen image, painting every other line on the first pass and sequentially filling in the rest of the line on the second pass. This scheme usually causes flicker. See also noninterlaced scanning mode. Invar shadow mask A special type of shadow mask, made out of Invar and alloy, that is able to withstand the high temperature generated by the electron beam. The Invar shadow mask allows the CRT to generate a brighter image than with the conventional shadow mask. An advanced Invar shadow mask improves brightness by 40 percent over the standard. ISO 9241 part 3 An ergonomic standard that covers hardware, software, workplace, and environment. It addresses the actual application at the work place. The objective of part 3 is to ensure that the CRT display shall be legible, readable, and comfortable in use.
LCD
Liquid crystal display. LCDs use two layers of polarizing material separated by a liquid crystal solution. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, controlled individually, acts like a shutter. Color LCDs use two basic techniques for producing color: Passive matrix is the less expensive, and active matrix, also called Thin Film Transistor (TFT), provides a sharper image. linearity The degree to which the actual location of a pixel on the screen corresponds with its intended location. Nonlinearity causes screen images to be more distorted in one area of the screen than in another. This is sometimes caused by poor voltage regulation in the monitor's electronics.
magnetic field effects (MFE)
A monitor is affected by magnetic fields. When a screen develops wrong colors in certain areas, or the picture becomes distorted, check what is located near the monitor. A steel cabinet, desk, bench, or steel girder imbedded in a wall or ceiling could cause distortion of the picture tube's electron beams due to an impeding magnetic field. Moving the monitor approximately 3 feet away from the suspected source can clear the problem, as can degaussing it. Speakers should also be considered as a possible source of distortion, since they may also create a magnetic field when powered on. memory In technical references, the word memory used by itself refers to random access memory (RAM). modem A device that allows one computer to communicate with another over phone lines. Can be inside a computer (internal) or external. All modern modems are also capable of sending and receiving faxes with the use of fax software. MPR II A set of Swedish safety standards that covers the levels of magnetic and electrical fields in both VLF and ELF ranges. The Swedish National Board for Measurement and Testing (SWEDAC) requires that products sold in Sweden comply with MPR II. To measure emissions, a sophisticated test that screens out background radiation must be in place. Since distance to the CRT and orientation of the measuring device affects measurement, precise placement of the measuring device is essential and difficult to repeat. In addition, the actual image displayed can have an impact on emissions, so that a given set of measurements may not predict the emissions a user would actually encounter. It is worth noting that there are no scientific studies that conclude that measurements above MPR II levels are hazardous. See also TCO95 and TCO99.
noninterlaced scanning mode
A scheme for assembling an image on the screen by painting all the lines in one pass, then painting an entirely new frame. Noninterlaced scanning mode reduces flicker. See also interlaced scanning mode.
operating system (OS)
The program that runs a computer. The operating system takes care of managing files and folders (such as renaming, moving, copying, and deleting files). It also provides the ability to start the other software you have on your computer. Operating systems also usually include many programs, such as a text editor, that are almost essential to have on every computer. opto-electronics Infrared-light emitting diodes (LEDs) and photo transistors used for touch-sensing in infrared (IR) touchscreens. opto-matrix frame Used in infrared (IR) touchscreens. The touch frame contains two opposite rows of IR-light emitting diodes (LEDs) and photo transistors, collectively referred to as opto-electronics, concealed behind an IR-transparent bezel.
passive matrix
See LCD. phosphor Chemical compound that emits light when excited by electrons. pixel Abbreviation for picture element, the smallest element of the picture that can be displayed on the screen. Each pixel contains one red, one blue, and one green phosphor. PDF file (Adobe® Portable Document Format) A universal file format that preserves the fonts, formatting, colors, and graphics of any source document, regardless of the application and platform used to create it. PDF is the open de facto standard for distributing formatted documents over the Internet. PDF files are compact and can be shared, viewed, navigated, and printed using free Adobe Acrobat® Reader® software, downloadable from http://www.adobe.com. Documents can be converted into PDF files with Adobe Acrobat software. point of information (POI) The location at a facility where visitors seek information. point of sale (POS) The location at a merchant's facility where customer make purchases. POS terminal A device placed in a merchant location, connected to the bank's system or authorization service provider via telephone lines, and designed to authorize, record, and forward data for each sale by electronic means.
RAM
Random access memory. In technical references simply referred to as memory. A computer's memory is not like its hard disk, which is permanent storage. Memory can only store information while the computer is on; however, it is much faster than a hard disk. A hard disk is a mechanical device, but memory is stored on computer chips, and information can be accessed from anywhere on the chip almost instantly. refresh rate Number of times the screen can be redrawn per second—an ergonomic issue directly related to long-term ease of use. A higher refresh rate means a less "flickering" display, resulting in less eyestrain and fatigue. Bandwidth, horizontal scanning rate, and vertical scanning rate work together to determine both the resolution and refresh rate. resolution The number of pixels that can be displayed on a screen, specified as the number of pixels in a horizontal line multiplied by the number of horizontal lines. For example, a resolution of 800 x 600 is 800 pixels running horizontally and 600 pixels running vertically-a total of 480,000 pixels. RF Radio frequency. It consists of electromagnetic waves at a frequency between audio and infrared, used primarily in radio and television transmission. RFI Radio frequency interference. This interference in the operation of a device is caused by incompatibility with ambient RF signals. See also EMC, EMI, and RF. RS-232 port A standardized serial port for connecting a computer to peripheral equipment, such as a printer, mouse, scanner, modem, or touchscreen.
screen size versus viewable
image size
Screen size is the total size, measured diagonally, of the monitor screen before it is placed in the monitor cabinet. Viewable image size is the size, measured diagonally, of the monitor screen that can be viewed once it is in the cabinet. stripe pitch The equivalent of dot pitch on aperture grille tubes—the distance between one stripe and the next one of the same color, expressed in millimeters.
TCO95 and TCO99
A standard set by the Swedish Tjnstemännens Central Organization (TCO) in 1991. It is even more stringent than MPR II, especially for alternating electric fields (AEF). Not only are the permitted field levels reduced compared with MPR II, but the measuring distance is reduced as well. Ergonomic and ecologic requirements are included for TCO95. For TCO99, it is expanded to include more ergonomic and ecologic requirements. See also MPR II. TFT Thin film transistor. See LCD. tilt The angle of the CRT with respect to the horizontal-mounting bracket of the chassis. Tilt can vary, depending on the monitor's orientation to the earth's magnetic poles. Monitor manufacturers orient and align their products in the eastern direction. When the monitor is facing a north/south direction, there may be a slight rotation of the image.
UL/cUL Listed
End products can be Listed by Underwriters Laboratories for expected safety concerns, The CNL/USL designation in the certification indicates evaluation to U.S. and Canadian standards. Typical end products are desktop touchmonitors. UR/cUR Recognized components Component products can be Recognized by Underwriters Laboratories for expected safety concerns. The CNR/USR designation in the certification indicates evaluation to U.S. and Canadian standards. Typical end products are touchscreens, controllers, and kiosk touchmonitors. USB Universal Serial Bus. An external bus standard that supports data transfer rates of 12 Mbps (12 million bits per second). A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. USB also supports Plug-and-Play installation. user-friendly Describes an interface-Web site, equipment, process-that people find easy to use, or intuitive.
VCCI
A Japanese standard for RF emissions developed by the Voluntary Control Council for Interference. The VCCI marking on an end product indicates it has been tested for compliance with the VCCI program. vertical frequency The number of times per second that a monitor can draw all the lines on an entire screen. A higher vertical frequency or refresh rate will reduce flicker, helping to reduce user eyestrain and stress. vertical scanning frequency In interlaced mode, the number of fields written to the screen every second, expressed in Hz. In noninterlaced mode, it is the number of frames (complete pictures) written to the screen every second (also known as refresh rate). A higher vertical frequency or refresh rate will reduce flicker, helping to reduce user eyestrain and stress. VESA Video Electronic Standards Association, a consortium of manufacturers formed to establish and maintain industrywide standards for video cards and monitors. VESA was instrumental in the introduction of the Super VGA and Extended VGA video graphics standards with a refresh rate of 70 Hz, minimizing flicker and helping to reduce user eyestrain and fatigue. See also video graphics adapter. video bandwidth See bandwidth. video graphics adapter (VGA) A card with a character generator and an array of microprocessors that translate bit information from the computer into displayable video signals for the monitor. These cards comply with various standards that determine the nature of the quality of the display. VGA, introduced in 1987, was the first analog card. It offered still higher resolution than enhanced graphics adapter (EGA)- 640 x 480 pixels for graphics and 720 x 400 pixels for text-and a color palette of 256 colors. VGA could also emulate EGA and color/graphics adapter (CGA). Super VGA (SVGA), devised by VESA in 1989, offers a resolution of 800 x 600 pixels. XGA-8514A, introduced by IBM in 1990, offers a resolution of 1024 x 768 pixels (interlaced) and a color palette of 256 colors. Extended VGA (XVGA), introduced by VESA in 1991, offers a top resolution of 1024 x 768 pixels (noninterlaced) and a refresh rate significantly higher than that of IBM's XGA-8514A. High-end graphics adapters, introduced in the late 1990s for professional workstations, offer top resolutions from 1280 x 1024 to 1600 x 1280, horizontal line frequencies up to 90 kHz, and bandwidths up to 200 MHz. video signal The output from the video graphics adapter incorporating the red (R), green (G), and blue (B) signals and the luminance signal, or combinations of these signals, that pass to the video input of the monitor. viewable image size (VIS) Actual maximum viewable image size is dependent upon the size of the plastic or bezel around the CRT. Typically, the maximum possible for a "17-inch" monitor is actually 15.75 inches, plus or minus 0.25 inch at the ends of diagonal measurement. VIS differs from diagonal linear measurement. VRAM/video memory Random access memory for storing video information. VRAM is a special purpose RAM with two data paths for access rather than the one path of a conventional RAM. The two paths let the VRAM handle two tasks simultaneously: display refresh and processor access. VRAM does not force the system to wait for one function to finish before starting another, so it permits faster operation for the video subsystem. |
