Glossary of Terms


HitachiDisplays VAR

How Monitors Work
How LCD's Work
How CRT's Work
Glossary of Terms

Active display area - the area on the face of the CRT that the image is displayed upon.

Active Matrix Display - A type of Liquid crystal display which uses Thin-Film Transistors (TFT) to control each pixel individually.

Anti-static - An adjective describing the class of materials which includes conductive materials that do not allow an electrical field to be built up or stored upon themselves. With an anti-static coating on the monitor’s CRT surface, no static electricity is built up, therefore, upon touching the CRT the end-user is not shocked and there is reduced dust build up.

Aperture Grill - A method of CRT construction employing vertical strips of phosphor separated by a grid of tiny metal wires. Light emitted from the electron gun passes through this grid of metal strings and is filtered and focused onto the back of the CRT, exciting phosphors that produce the on-screen image.

Aperture Pitch - The equivalent of horizontal dot pitch on shadow mask CRTs; the distance between one stripe and the next one of the same color, expressed in millimeters. Also known as Stripe Pitch. See Horizontal Dot Pitch and Dot Pitch.

Auto Setup - A monitor feature that automatically adjusts the screen size and position most appropriate for the video signal received.

Bandwidth - Expressed in megahertz (MHz), bandwidth is often called Pixel Clock. Bandwidth is a measurement of a monitor's pixel clock. This is a qualitative term used to describe the monitor's video amplifier performance. The higher the pixel clock, the higher the Bandwidth requirement of the Video Amplifier. Bandwidth refers to the highest signal frequency a monitor's circuit can display. The higher the
bandwidth, the higher the resolution and the sharper the image will be.

Beam - The electron beam in the CRT, which makes contact with the phosphors on the CRT surface, activates them and causes them to produce different red, green and blue light depending on the phosphor.

Brightness - The control that adjusts the image’s light output.

Brightness Control - The black level control was historically - and misleadingly - labeled brightness. The brightness control is misleading because the apparent brightness of the screen is not actually being changed. Rather, by adjusting the brightness (black level) you are changing the contrast ratio of your screen or the apparent blackness of the screen. Adjust brightness so that the black region of the picture is as black as possible, but just on the threshold of becoming visible.

Contrast Control - Determines the light intensity produced for white. Once you have set black level or brightness, use the contrast control to adjust the contrast level to set a comfortable maximum intensity. Resist the temptation to set your monitor too bright. White should be a pleasant white, it doesn't have to illuminate your room.

Contrast Ratio - Contrast ratio is the ratio of light intensity between the brightest white that can be produced and the darkest black that can be produced. Contrast ratio is a major determinant of perceived picture quality: if a picture has high contrast ratio, you will judge it to be sharper than a picture with lower contrast ratio and consequently reduce eyestrain and increase readability.

Convergence - A computer monitor's ability to correctly align the red, blue and green phosphor dots to form the elements of an image on the back of the CRT screen. Any misalignment will cause a colored border around the edge of a line, character, or image where a white background should exist.

CRT - Cathode Ray Tube, commonly known as picture tube.

Dot Pitch - The distance of one phosphor dot to the nearest dot of the same color on the adjacent line. See Horizontal dot pitch and Aperture pitch.

Dead Pixel - Limitations of the LCD manufacturing process sometimes result in dead sub-pixels. Three sub-pixels one red, one green and one blue make up a "Pixel". A dead "pixel" three adjacent sub-pixels is rare, however dead sub-pixels are very common. A "dead sub-pixel" can take the form of either a black or colored spot on a white background or a white or colored dot on a black background. Since this is a manufacturing issue sub-pixels typically will not go bad over time.

Drivers- Monitor INF files are often referred to as monitor drivers. In fact .INF files are simply a text file that lists the capabilities of your monitor. Anything that directly affects your monitor, changing resolution for instance will refer to the corresponding INF to ensure that the change doesn't make demands outside of your monitor's recommended operating parameters.

DVI - Digital Video Interface. There are two common versions of DVI. DVI-I carries both analog and digital interfaces, while the DVI-D has only the digital.

Electronic Gun - The device in the CRT that produces the electron beam that is attracted to the phosphors on the face of the CRT; this activates the phosphors thus causing them to emit red, green or blue light.

Ergonomic - Applies biological and engineering solutions to problems relating to the individual and their working relationship with machines.

Ergo Flat - Ergo Flat is Hitachi's brand name for its flat-faced monitor and what many call "Perfectly flat" or Natural Flat".

FCC - Federal Communications Commission. The U.S. commission regulates the radio frequencies over the airwaves.

Flat Square CRT - Flat, Square is an industry standard term used since 1997 indicating minimal curvature (but still a curvature) of the monitor tube.

Flicker - Perceived in CRT monitors with low refresh rates (below 85Hz), flicker is the visible unsteadiness caused by the monitor "repainting" its on-screen image at a speed that is slow enough to be detected by the human eye. Flicker is the primary cause of vision-related problems. LCD monitors do not suffer from flicker.

Frequency Range - the high and low limits of the frequencies that can be used with your monitor. Usually pertains to horizontal and vertical sync ranges.

Graphics board or card - See Video Card

Horizontal Dot Pitch - The distance between one phosphor dot and the next one of the same color measured horizontally, expressed in millimeters. Dot pitch gives a general idea of the monitor's ability to produce sharp images: the smaller the dot (aperture) pitch, the sharper the image. See Aperture Pitch and Dot Pitch.

Horizontal Frequency - Monitors draw pictures one horizontal line at a time, going from the top left to the bottom right. The horizontal scanning frequency, also called the line scan rate, horizontal frequency or horizontal scanning frequency, is a measure of how many horizontal lines the display draws per second and is given in kilohertz (kHz).

IPS - In plane switching. Technology used in LCD monitors to improve viewing angle, brightness, contrast and color fidelity.

Invar Shadow Mask - A monitor technology where light is emitted through a heat resistant metal sheet containing numerous holes. Basically, this thin sheet of metal has holes corresponding to each phosphor dot on the CRT and causes the correct red, green and blue electron gun beam to hit the correct color phosphor.

KHz (Kilohertz) - A unit of frequency equal to one thousand cycles per second.

LCD - (Liquid Crystal Display) - A Liquid Crystal Display (LCD) is a non-emissive display. LCDs are used in digital watches, calculators, televisions, and computer monitors. LCDs offer the advantages of being lightweight, compact, and more energy efficient compared to conventional CRT monitors.

Magnetic Field - A state produced in a medium, either by electrical current flow in a conductor or by permanent magnet, that can induce voltage in a second conductor. CRT monitors are prone to magnetic interference. Anything that creates a magnetic field may influence your monitor. Fans, motors, large speakers, elevators etc.

MHz (Megahertz) - A unit of frequency equal to one million cycles per second.

Moiré - Moiré patterns are interference patterns, which may appear on a monitor's CRT. A moiré effect has the appearance of a wavy pattern that is repetitive and superimposed on the screen as rippled images. The focus of a monitor effects the clarity of the image on-screen. Ironically, the better the focus on the monitor, the worse the moiré is likely to be.

Multiscan Monitor - Monitors that are capable of displaying a range of resolutions or graphics standards having different horizontal and vertical frequencies.

Native Resolution - On LCD monitors the pixel pitch multiplied by the resolution defines the screen size of the monitor. Thus they are a fixed or native resolution devices. For example a 15" LCD has a pixel pitch of 0.3mm and 1024 horizontal resolution. 1024 x 0.3 = 307mm horizontal. 768 x 0.3 = 230mm. Using Pythagorean theory this works out to 15" Diagonal.

Phosphor - Phosphorescent substance of red, green and blue that emit light when activated by electrons.

Pin Cushion - The appearance of curved edges on the display image inward.

Pixel - A definable location on a display screen that consists of multiple or single triad of dots (red, green and blue).

Pixel Response Time - The Pixel response time is the total rise/fall time of the pixels typically measured in seconds (ms). This represents the amount of time it takes for a point on the screen to go from completely white to completely black.

Raster - The overall area that is scanned by the electron guns.

Refresh rate - The rate, measured in Hz, in which a monitor refreshes or "repaints" the image on the screen, in the period of one second. A monitor with a refresh rate any lower than 85Hz may refresh slow enough to be noticed by the human eye, creating a visible phenomenon referred to as flicker. LCD monitors do not suffer from flicker even at low refresh rates.

Resolution - The number of dots (consisting of one or more pixels) displayed on the screen; typically stated in number of dots per line by number of lines; the higher the resolution, the greater the amount of detail that can be displayed or the sharper the image; if standard, a resolution will be called a graphics standard.

RGB Video Output - The monitor receives red, green, and blue signals separately from the computer. These signals are sent directly to the electron guns for processing (in contrast to composite video output).

Shadow Mask - A type of CRT construction that uses a metal mask of tiny holes (instead of the wire grid of a Aperture Grille) to shield and direct the electron beams from the electron gun onto the phosphor dots on the back face of the CRT tube. Shadow mask is the prevailing technology for detail-intensive, CAD/CAM, precision graphics, and text-intensive applications.

Signal Cable - The cable that connects the monitor to the video card or computer’s graphic output.

Static Electricity - The electrical charges that are developed on the surface of the CRT when it is turned on. Not only does this electrical charge cause a shock when the CRT is touched, but it also attracts dust to the surface of the CRT.

SWEDAC - Swedish Board for Technical Accreditation. This council provides the recommendations for the magnetic field emissions guidelines. Its previous name was MPR.

Sync - The horizontal and vertical signals that control the scan rates of the monitor.

TCO - A rating factor by the Swedish National Board of Measurement and Testing. This council produces the recommendations for the magnetic and electrical field emissions guidelines. The council’s name has been changed to SWEDAC. TCO-99 is the most current standard

TFT - Thin Film Transistor. Technology used in flat panel LCD liquid crystal displays

UL - Underwriters Laboratory. A non-profit safety organization in the U.S. that inspects and certifies the products sold in the U.S. for their safety standards.

Vertical Frequency - The inverse of the time it takes for a monitor to scan the whole screen; typically states in hertz.

Vertical Scan - The act of the electron beam sweeping across the entire face of the CRT (or sweeps across all the lines on the CRT once).

VESA - See Video Electronics Standards Association.

VGA - Video Graphics Array

Video Adapter - See Video Card.

Video Card - A circuit board or on-board circuit that is mounted inside the computer and produces the signals necessary for the monitor to display information.

Video Connector - The connector on the video card or computer’s graphics output that the monitor cable is connected to.

Video Controller - See Video Card.

Video Electronics Standards Association (VESA) - A non-profit member organization dedicated to facilitating and promoting personal computer graphics through improved graphics standards for the benefit of the end-user.

VESA Standard - Monitors with prime setting running at a frequency of 85Hz or greater.

XGA- Extended Graphics Adapter; IBM’s graphics standard that includes VGA and extended resolutions up to 1024 pixels by 768 lines.