Elo Touch Monitor Glossary

Elo Monitor Glossary

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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.

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 current monitors are as follows:

VGA monitors: 18 MHz
FGA+ monitors: 35 MHz
CAD monitors: 100 MHz

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.

Contrast
Contrast is 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.

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 is a very advanced feature that allows the user to switch to any required mode at any instant without having to spend time readjusting the picture.

Dot Pitch
Dot pitch is 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 standard. VESA standard that ensures that monitor and video card manufacturers produce power-saving products that work together.

EDID
Extended Display Identification Data, a VESA standard. 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 and TCO.

Energy Star
ENERGY STAR is 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.

Flat Square Screen
A screen that is flatter and squarer than the conventional CRT screen. The flatter outline reduces picture distortion, reduces 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 result is a “flickering” particularly detectable via peripheral vision. Flicker can be eliminated by increasing the refresh rate to a value at or above 70 Hz.

Hertz
The unit of frequency named after the physicist Heinrich Hertz (1857-1894). 1 hertz (Hz) is equal to 1 cycle/second.

Horizontal Frequency
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 better the monitor (i.e., the higher the resolution and/or the higher the refresh rate).

I²C Bus: Access Bus Standard
A standard-protocol 2-wire (clock and data) serial data bus.

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.

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 the conventional shadow mask. An advanced Invar shadow mask improves brightness by 40 percent over the standard.

ISO 9241 part 3
ISO 9241 is 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.

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
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 monitor positioned near a steel cabinet, desk, bench, or steel girder imbedded in a wall or ceiling could distort a 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 may also create a magnetic field when they are powered on, and should be considered as a possible source of distortion.

MPR II
The Swedish National Board for Measurement and Testing (SWEDAC) requires that products sold in Sweden comply with a set of safety standards known as MPR II, which covers the levels of magnetic and electrical fields in both VLF and ELF ranges. It is worth noting that there are no scientific studies that conclude that measurements above MPR II levels are hazardous. 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.

Non-Interlaced Scanning Mode
A scheme for painting an on-screen image that paints all the lines in one pass and then paints an entirely new frame. A non-interlaced scanning mode reduces flicker.

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.

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 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, making a total of 480,000 pixels.

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 vs. 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.

TCO
In 1991, the Swedish Tjänstemännens Central Organization (TCO) set a standard 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.

Tilt
Tilt is 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.

USB
Universal Serial Bus, a new 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.

Vertical Frequency
Vertical frequency indicates how many times per second the monitor can draw all the lines on an entire screen. A higher vertical frequency or refresh rate will reduce flicker.

Vertical Scanning Frequency
Expressed in Hz, interlaced mode, this is the number of fields written to the screen every second. In non-interlaced 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.

VESA
Video Electronic Standards Association, a consortium of manufacturers formed to establish and maintain industry-wide 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 operator fatigue and stress. See also Video Graphics Adapters.

Video Bandwidth
See Bandwidth.

Video Graphics Adapters
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 (Video Graphics Array), introduced in 1987, was the first analog card. It offered still higher resolution than EGA: 640 x 480 pixels for graphics and 720 x 400 pixels for test, and a color palette of 256 colors. VGA could also emulate EGA and 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 (non-interlaced) and a refresh rate significantly higher than IBM’s XGA-8514A.
High-end, graphics adapters, introduced over the last three years 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 the 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.