| A/D Converter |
(Analog/Digital converter) A device that converts continuously varying analog signals from instruments that monitor such conditions as movement, temperature, sound, etc., into binary code for the computer. It may be contained on a single chip or can be one circuit within a chip |
| absolute white |
In theory, a material that perfectly reflects all light energy at every visible wavelength. In practice, a solid white (with known spectral data) that is used as the "reference white" for all measurements of absolute reflectance. |
| achromatic |
A neutral color (white, gray, or black) that has no hue. See hue. |
| Active Area/Effective Area |
In the viewing area of the LCD glass, the dimensions of the perimeter of the conductive area. |
| active matrix |
A liquid crystal display structure in which switching transistors or diodes are attached to each pixel to control the on/off voltage. It produces a brighter and sharper display with a broader viewing angle than a passive matrix display. Also known as AMLCD (active matrix liquid crystal display). See TFT (thin film transistor). |
| Active Matrix Display |
A type of flat panel display in which each pixel has it's own transistor `switch' rather than being activated by it's address within a matrix of rows and columns. This direct switching radically improves response times enabling full-motion video to be shown without blurring. |
| Active Matrix TFT |
The most common type of LCD (Liquid Crystal Display) used in the majority of laptops and most LCD panels and projectors. A typical active matrix TFT display is a single panel of LCD glass that modulates all three primary colors. Most of these offer contrast ratios up to 100:1 for good color dynamics, and just enough speed to handle video and 30fps multimedia with little or barely distinguishable hesitation (jerkiness). |
| ADC (Apple Display Connector) |
Proprietary connector used to carry digital video signal and USB data to the CPU. Also used to power the display. |
| additive primaries |
In color reproduction, red, green, and blue. When lights in these colors are combined in equal amounts, they produce the visual sensation of white light. When these are combined at varying intensities, a range of different colors is produced. Combining two primaries at 100% produces a subtractive primary, either cyan, magenta, or yellow. See subtractive primaries. |
| alignment layer |
A thin film layer that is applied by spin coating. This thin film is then treated to impart a desired direction at which the liquid crystal molecules will attach and align. See buffing. |
| amorphous silicon (a-Si) |
A semiconductor material that is used to make the thin film transistors (TFTs) layer of an active matrix LCD. |
| Analog |
In analog technology, a wave is recorded or used in its original form, as opposed to being "digitized" and reduced to a signal created from ones and zeros (see Digital |
| Analog to Digital Conversion |
LCD monitors with an analog interface can accept an analog video signal using standard RGB connectors for personal computers, in the same way as a CRT monitor. The analog signal is then converted into the digital signal used for display on a LCD panel. LCD monitors with only a digital interface require a dedicated graphics adapter and connectors, which come in varied formats. |
| Annunciator |
An active element, such as a symbol, word, or phrase. |
| ANSI-HFS |
(American National Standard for Human Factors Engineering of Visual Display Terminal Workstations). Organization that produces publications concerning the ergonomics of monitors. |
| Anti-glare Screen or Filter |
A treated glass panel that is placed over a monitor screen to reduce glare from light sources. Non-glare CRTs often use a coating baked onto the screen at the time of manufacture, which provides a significant reduction in glare; however, LCD screens may completely eliminate it. |
| aperture ratio |
The ratio between the transmissive portion of the pixel and its surrounding electronics, also known as fill factor. Generally, this is a limiting factor for luminance, the higher the aperture ratio; the brighter the luminance. |
| aspect ratio |
The width-to-height ratio of the active area of a display. Standard U.S. video has an aspect ratio of 4:3. |
| Auto Adjust |
A special one-touch Auto Adjust button allows users to quickly set the display panel to match their preferences and provides users with excellent front-of-screen performance and minimal set up. |
| Auto Sync |
Same as Auto Adjust. |
| backlight |
The light source for a transmissive LCD. Basically, two techniques are used in transmissive LCD designs, direct lighting and side lighting. Direct-lit backlights use CCFTs (cold cathode fluorescent tubes) and a diffuser panel directly in back of the LC (liquid crystal) layer. Side-lit backlights use CCFTs and a light pipe on one or more of the edges of the display. |
| Backlighting |
A technique used to make flat-panel displays easier to read in low ambient light conditions. The most commonly used types of backlighting are LED, EL (electro luminescent) or CCFL (Cold Cathode Fluorescent). |
| 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. As projectors have gotten brighter, room lights tend to stay on, so while nice, having backlit controls is no longer important to many users. |
| Bandwidth |
The speed, measured in megahertz, at which the data can be accepted from the CPU/graphics adapter to the monitor. A greater speed means that higher resolutions can be shown with more brightness and clarity. |
| Bezel |
A metal or plastic frame which fits over the LCD glass to protect the edges of the glass. The bezel acts as a pressure device, compressing the elastomer connector between the LCD glass and PCB. |
| Bit Depth |
See Color Depth |
| black |
Ideally, the complete absorption of incident light; the absence of any reflection. In the practical sense, any color which is close to this ideal in a relative viewing situation, i.e., a color of very low saturation and of low luminance. |
| brightness |
The dimension of color that is referred to an achromatic scale, ranging from black to white, also called lightness or luminous reflectance. Because of confusion with saturation, the use of this term should be discouraged. |
| buffing |
A technique where the alignment layer on the LCD substrate is rubbed in one or more directions. This process aligns the liquid crystal molecules parallel to the buffing direction. See alignment layer. |
| Candelas (cd/m2) |
An international unit of luminous intensity per projected area normal to the line of observation. Luminance may be described in units of Candelas per square meter, or nits. |
| CCFTs (cold cathode fluorescent tubes) |
These are the fluorescent tubes that provide the light for the LCD unit. These tubes are generally very thin, approximately 2 mm in diameter. See fluorescent lamp. |
| Cell |
See subpixel. |
| Cell Gap |
The spacing between the two pieces of glass. This space contains the liquid crystal fluid. |
| Chip-on-board |
The LCD driver is formatted into an area on the PCB. Electrical connections are made by micro diameter gold wires. The entire area is then covered with epoxy. |
| Chip-on-flex |
The LCD driver is incorporated into a flex connector, which is attached to the contact edge of the LCD glass. |
| Chip-on-glass |
A new technology where the LCD driver is actually mounted on the surface of the LCD glass. |
| chromatic |
Perceived as having a hue; not white, gray, or black. |
| chromaticity |
That part of color specification, which does not involve illuminance. Chromaticity is two-dimensional and specified by pairs of numbers such as dominant wavelength and purity. |
| chromaticity coordinates, CIE |
The ratios of each of the three tristimulus values X, Y, and Z in relation to the sum of the three: designated as x, y, and z respectively. They are sometimes referred to as the trichromatic coefficients. When written without subscripts they are assumed to have been calculated for Illuminant C and the 2° (1931) standard observer unless specified otherwise. If they have been obtained for other illuminants or observers, a subscript describing the observer or illuminant should be used. For example, x10 and y10 are chromaticity coordinates for the 10° observer and Illuminant C. |
| chromaticity diagram, CIE x,y |
CIE Cromacity Diagram A two-dimensional graph of the chromaticity coordinates, x as the abscissa and y as the ordinate, which shows the spectrum locus (chromaticity coordinates of monochromatic light, 380 nm-770 nm). It has many useful properties for comparing colors of both luminous and non–luminous materials. |
| CIE (Commission Internationale de l'Eclairage) |
The International Commission on Illumination, the primary international organization concerned with color and color measurement. |
| CIE chromaticity coordinates |
The ratios of each of the tristimulus values of a color to the sum of the tristimulus values. In the CIE systems they are designated by x, y, and z. |
| CIE standard observer |
A hypothetical observer having the tristimulus color-mixture data recommended in 1931 by the CIE for a 2° viewing angle. A supplementary observer for a larger angle of 10° was adopted in 1964. If not specified, the 2° standard observer should be assumed. If the field of view is larger than 4°, the 10° standard observer should be used. |
| Cold Cathode Backlight (CCFT) |
In LCD graphic modules, a type of fluorescent backlighting or edge lighting. One or more fluorescent lamps behind the LCD panel that provides the light that is either blocked (black) or passed (white) by the LCD cell. Used in medium to large size graphic LCD modules. |
| Color Calibration |
The necessary adjustment of colors that causes the colors on the monitor to match the ones produced by the printer. Without adequate calibration, the printed page may not accurately reproduce what is displayed on the computer screen. |
| Color Depth |
Color depth is determined by the number of bits used to produce color in each pixel on a monitor display. The more bits used, the greater the number of colors that can be displayed, provided that a graphics card and monitor have the capability to display them. Common bit ranges are 8-bit color (256 colors), 16-bit color (thousands of colors), and 24-bit color (millions of colors). Most monitors in use today can display at least 16-bit color, and new monitors can usually handle 24-bit color. |
| Color Matching |
Color matching refers to the process of accurate duplication of colors between the display and either input (like a VGA card) or output (like a printer). An LCD display with color matching stores color-related parameters in special memory called EEPROM, and uses this data for optimization, providing benefits such as WYSIWYG printing and faithful representation of Web graphics. |
| color temperature |
A measurement of the color of light radiated by an object while it is being heated. This measurement is express in terms of absolute scale, or degrees Kelvin. Lower Kelvin temperatures such as 2400° K are red; higher temperatures such as 9300° K are blue. Neutral temperature is white, at 6504° K. |
| column driver |
Small electronic circuits that provide voltages to the individual sub-pixel through the source lines. These are generally 8-bit driver circuits that provide 256 unique values per sub-pixel. |
| Common/Backplane |
The conductive surface on one of the two pieces of glass, which superimposes the pattern on the second piece of glass. The number of backplanes corresponds to the duty ratio. |
| Contact Edge |
The extended area of the LCD glass which contains the conductive leads/traces, to which electrical connections is made by a connector. |
| contrast |
The level of variation between light and dark areas in an image. |
| Contrast Ratio |
The difference in luminance between a white square centered on the screen and the black surrounding area. A method of measuring the dynamic range. A contrast ratio of 15:1 (passive matrix LCDs), offers washed out colors, little detail and image that can barely survive with significant ambient light. Projectors with active matrix TFTs have ratios to 100:1, DLPs from 125:1 and Poly-Si Liquid Crystal Displays 200:2.By comparison, transparency film (i.e. 35mm slides) have contrast ratios over 500:1. |
| Convergence |
1) The clarity and sharpness of each pixel. 2)Alignment of the vertical and horizontal lines in an image. |
| CRTCathode Ray Tube |
The type of technology that has been used in television sets and computer monitors for many years. A rapidly moving electron gun inside the set passes across the screen, casting a beam that lights selected phosphor dots as it moves. The dots are arranged in groups of three, forming "pixels" which can be lighted as red, blue, or green. By moving across rows of these pixels rapidly from top to bottom, the electron beam creates a continuously changing, lighted screen that the eye resolves into an image. |
| CSTN - Color Super-Twist Nematic |
CSTN is an abbreviation of Color Super-Twist Nematic, a Liquid Crystal Display technology to produce full-color.Unlike TFT, CSTN is based on a passive matrix, which is less expensive to produce.The original CSTN displays developed in the early 1990's suffered from slow response times and ghosting. Recent advances in the technology, however, have made CSTN a viable alternative to active matrix displays.New CSTN displays offer 100ms response times, a 140 degree viewing angle and high quality color rivaling TFT displays.A newer passive-matrix technology called High Performance Addressing (HPA) offers even better response times and contrast than CSTN. |
| Cursor |
A row or block of dots, used to indicate the location of the next character or symbol to be entered. Used in dot matrix character and graphic LCD modules. |
| DDC (Used by Plug and Play monitors) |
Short for 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. |
| DDC1 |
Display Data Channel 1. A uni-directional data channel from the display to the host, continuously transmitting Extended Display Indentification, EDID information. |
| DDC2 |
Display Data Channel 2. A bi-directional data channel based on the 12C protocol. The host can request EDID or VDIF information over the DDC2 channel. In addition to this, the DDc2 channel can act as a transparent channel for ACCESS.bus communication. |
| Degauss |
To remove an unwanted magnetic field from an electronic device, e.g. television tube or CRT |
| 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. Throughout this document we assume that the diagonal dimensions are for the traditional 4:3 ratio of a computer image as per the example above. Some screens are square, others particularly wide for 35mm slides 3:2 ratio. As such even if the screen is 12x12, we would rate it 15FT diagonal since that would be the diagonal of the usable area.
OK, how about this! Remember high school? Here's your old geometry lesson. X-squared times Y-squared equals Z-squared. 3ft by 4ft screen = 3 squared (9), + 4 squared (16), equals 25 (5 squared) a 5 ft diagonal image. |
| DICOM |
(Digital Imaging and Communications in Medicine). The DICOM standard contains a display function standard. |
| Digital |
As mentioned above, analog technology records and plays back data (audio, video, etc.) in the form of analog waves. The main drawback with this is that over time the quality of the physical wave signal may degrade (this is evident when playing an old LP or VHS tape.) By contrast, digital technology records and plays back data as strings of zeros and ones (binary data.) Because this data is coded into strings of numbers, it is not susceptible to signal degradation in the same manner as analog data |
| Digital Controls |
High-tech SoftTouch digital controls electronically sense the slightest touch for easy adjustments of size, position and tuning at all resolutions |
| digital driving level (DDL) |
A digital value which given as input to a display system produces a luminance. The set of DDLs of a display system is all the possible discrete values that can produce luminance values on the display system. The mapping of DDLs to luminance values for a display system produces the characteristic curve of that display system. The actual output for a given DDL is specific to the display system and is not corrected for the grayscale standard display function. |
| DIL (Dual-In-Line) |
Two parallel rows of connection holes on a PCB. Also refers to the type of connector needed with this array. |
| Dil Pins |
Individual metal pins, bonded by epoxy, to each conductive lead/trace on the contact edge. |
| Direct/Static Drive |
Each conductive lead on the contact edge, connects to one segment or annunciator. |
| Display Modes |
Specific frequencies at which the monitor (and/or computer) can display text or graphical information. Most monitors today support several frequencies. This is called multifrequency or multi-scanning, and it ensures that the monitor will perform with a variety of computers and applications. |
| Dithering and Display Colors |
TFT LCD panels support either 6-bit or 8-bit RGB color output, allowing them to display 262K or 16.7M distinct colors, respectively. Using so-called dithering techniques, an analog-to-digital signal processor can simulate 8-bit RGB color output on an LCD panel that actually supports only 6-bit color. |
| Dot Matrix |
A group of dots/pixels forming a character or symbol. The most common dot matrix is a 5 x 7 matrix (5 dots across; 7 dots down). |
| Dot Pitch |
The distance between pixels on a CRT. Depending on the manufacturer, dot pitch distance is measured diagonally, horizontally, or both. The smaller the dot pitch, the sharper the image. |
| Dot/Pixel (Picture Element) |
The smallest active element that forms all text and graphics on the LCD screen. Typically a rectangular active element, when combined together in a matrix, forms a character or symbol. |
| Double Layer STN |
A passive matrix LCD (Liquid Crystal Display) technology that uses an extra compensating layer to provide a sharper image, sometimes called F-STN or Film Compensated Supertwist. |
| double-domain |
A technique used to improve the viewing angle where multiple alignment directions are produced on the same sub–pixel. |
| DSTN - Dual Scan STN |
An enhanced STN passive matrix LCD (Liquid Crystal Display). The screen is divided into halves and each half is scanned simultaneously, thereby doubling the number of lines refreshed per second and providing a sharper appearance. DSTN is widely used on laptops and Point of Sale Terminals. |
| Dual Scan Passive Matrix |
Newer version of the original passive matrix technology, where the screen is controlled by two processing systems. They are faster than "single scan" displays, but still slower than most TFTs. Dual Scan Passive Matrix displays are most useful where response speed is not critical. |
| Dual-Scan Display |
A type of passive matrix LCD (Liquid Crystal Display) that provides faster refresh rates than conventional passive matrix displays by dividing the screen into two sections that are refreshed simultaneously.Dual scan displays are generally not as sharp or bright as active matrix displays, but they consume less power. |
| Duty Ratio |
1/N, where N equals the number of energized or unenergized segments selected by one complete cycle. |
| DVI – Digital Video Interface |
An emerging standard for digital display connections to personal computers |
| EL - Electroluminescent Display |
A technology used to produce a very thin display screen, called a flat panel display, used in some portable equipment. An ELD works by sandwiching a thin film of phosphorescent substance between two plates. One plate is coated with vertical wires and the other with horizontal wires, forming a grid.When an electrical current is passed through a horizontal and vertical wire, the phosphorescent film at the intersection glows, creating a point of light or pixel.EL Displays, being an emissive technology (rather than shuttering a light source as per LCDs) are most useful in applications where high visibility in all light conditions is essential. |
| Elastomer Connector |
A strip of silicone rubber made up of sequentially spaced conductive and non-conductive material. This is the most common connection method for LCD modules. |
| Electroluminescent Lamp |
Is a thin membrane consisting of two coated electrode plates with an aluminum reflector. When AC voltage is applied to the electrodes, the electrons collide with the light emission core. The energy given off is light. |
| Electrophoresis |
A phenomenon which occurs when excess DC voltage is applied to an LCD. Conductive particles from one piece of glass are transferred through the LC fluid and deposited on the conductive surface of the opposite piece of glass. A conductive spike is created thus causing a dead short. |
| Energy Star |
A program established by the Environmental Protection Agency (EPA) as a partnership with the computer industry to promote the introduction of energy-efficient personal computers which help reduce air pollution caused by power generation. This program was formally launched on June 17, 1993. To comply with the Energy Star guidelines, a computer system or monitor must consume less than 30 watts of power in its lowest power state. |
| ErgoDesign® Features |
Enhance human ergonomics to improve the working environment, protect the health of the user, and save money. Examples include OSM controls for quick and easy image adjustments, tilt/swivel base for preferred angle of vision, and compliance with MPRII guidelines for lower emissions. |
| Fiber Optic Backlight |
Fiber optics are flattened and then sandwiched between two pieces of pliable plastic. The top piece is used as the diffuser. The opposite ends are tied into a coupler, which is connected to an LED or Halogen light source. |
| Fill Hole |
A space left between the epoxy seals, after assembly on one end of the LCD glass. This space is used to fill the glass with the LC fluid, which is noted by a mound of epoxy on one end of the glass. |
| Flat Panel Display |
A very thin display screen used in portable computers. Nearly all modern flat panel displays use LCD (Liquid Crystal Display) technologies.Most LCD screens are backlit to make them easier to read in bright environments. Another example of a flat panel display is the gas plasma display screen. |
| fluorescent lamp |
A glass tube filled with mercury gas and coated on its inner surface with phosphors. When the gas is charged with an electrical current, radiation is produced which in turn energizes the phosphors, causing the phosphors to glow. |
| Font |
The active pattern which has all information to be displayed in the LCD glass. |
| foot Lamberts (fL) |
A unit of luminance. One foot Lambert is equal to 10.76/? (approximately 3.426) Candelas per square meter. |
| FPMPM |
VESA Standard Physical Mounting Interface Standard |
| gamma |
Screen luminance as a function of video voltage approximately follows a mathematical power function of the input video signal, the exponent of which is called gamma. |
| gate electrode |
The "row" electrode in an active matrix LCD that controls whether a voltage is applied to a sub-pixel. |
| Ghosting |
A phenomenon occurring when voltage from an energized element leaks to an adjacent OFF element and turns the adjacent element partially ON. Also, the temporary trail left by a moving object on a "slow" LCD panel |
| Graphics controller |
A generic term used to describe the video hardware in a computer. Although graphics hardware was traditionally integrated into the motherboard hardware, today this hardware is most frequently available as a separate PCI or AGP card. The graphics controller is responsible for generating the video signal that is sent to the monitor. Graphics controllers today are often built with their own processors and RAM on the card. |
| Grayscale |
An achromatic scale ranging from black through a series of successively lighter grays to white. Such a series may be made up of steps, which appear to be equally distant from one another or may be arranged according to some other criteria such as a geometric progression based on lightness. |
| Heat Seal |
A flat, flexible, adhesive connector which is bonded to the contact edge of the glass by heat. Typically used on large graphic modules. |
| 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. |
| Horizontal Frequency |
The number of lines illuminated on a video screen in one second. For example, a resolution of 400 lines refreshed 60 times per second requires a scan rate of 24KHz plus overhead (time to bring the beam back to the beginning of the next line). See also Scan Rate. |
| hue |
The main attribute of a color that distinguishes it from other colors. For example, a color may have a green, yellow, or purple hue. Colors defined as having hue are known as chromatic colors. White, black, and grays possess no hue. |
| In-Plane Switching (IPS) |
A liquid crystal technology in which the alignment field is generated from electrodes located on a single substrate rather than on opposite sides like more conventional (TN) panels. The main advantages IPS are greater viewing angles and greater contrast ratio. |
| Interconnect Dot |
Connects pattern piece of glass to each backplane. Consists of silver impregnated epoxy. |
| Interlaced |
Every other line is scanned during each total vertical (full) screen refresh |
| Inverse/Reverse Image |
Used exclusively on negative image graphic displays (transmissive negative). With EL or cold cathode backlight where the background is energized and the information to be displayed remains static or the same color as the polarizer in the OFF state. This is achieved by inverting the signal of the data lines before going to the LCD module. |
| Inverter (DC to AC) |
Used to power electroluminescent and CCFL lamps. Converts DC to AC voltage at a high frequency 300Hz ~1 kHz. |
| IPS (In Plane Switching) |
A technique of improving the viewing angle of an LCD where the liquid crystal molecules are switched in the plane of the LCD layer rather than vertical to it. |
| Isotropic Stage |
When the fluid heats up or cools down to the point where the fluid is no longer in the twisted nematic state. The molecules can no longer twist light and, therefore, all incoming light is absorbed. In positive image displays, the viewing area turns completely dark. The display will revert back to the twisted nematic state when cooled below the isotropic temperature. |
| JND (Just Noticeable Difference) |
The luminance difference of a given target under given viewing conditions that the average human observer can just perceive. |
| landscape |
A page or screen orientation that is wider than it is tall. |
| Latency |
The time delay that occurs when a computer is converting a signal into a form it can read (for example, from analog to digital.) A long latency period can result in such behavior as pausing or hanging video. See ghosting |
| LCD (Liquid Crystal Display) |
LCD, an abbreviation of Liquid Crystal Display, is a type of display used in digital watches and many portable devices. LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light.Monochrome LCD images usually appear as blue or dark gray images on top of a grayish-white background. Color Liquid Crystal Displays use two basic techniques for producing color. Passive matrix is the less expensive of the two technologies.The other technology, called thin film transistor (TFT) or active matrix produces color images that are as sharp as traditional CRT displays, but the technology is relatively expensive.Recent passive matrix displays using new CSTN and DSTN technologies produce sharp colors rivaling active matrix displays.Most Liquid Crystal Display screens used in notebook computers are backlit to make them easier to read. |
| LCD (Liquid Crystal Display) Monitor |
A monitor that uses LCD (Liquid Crystal Display) technologies rather than the conventional CRT technologies used by most desktop monitors.Until recently, LCD panels were used exclusively in notebook computers (laptops) and other portable devices. In 1997, however, several manufacturers began offering full-size Liquid Crystal Display Monitors as alternatives to CRT monitors.The main advantage of LCD displays is that they take up less desk space and are lighter. Currently, however, they are also much more expensive |
| LCD (Liquid Crystal Display) Technology |
LCD (Liquid Crystal Display) is the technology used for displays in notebook, smaller computers, portable devices including Mobile Telecoms (Telecommunication) pagers, phones, PDAs, EPOS and other instrumentation monitors. Like light-emitting diode and gas-plasma technologies, LCDs allow displays to be much thinner than cathode ray tube (CRT) technology. Liquid crystal Displays consume much less power than LED and gas displays because they work on the principle of shuttering light rather than emitting it.LCD fluids are selectable for individual display projects, with TN the original technology and HTN, STN and F-STN being developments. Liquid crystal displays are the most popular display medium for applications large and small.An LCD is made with either a passive matrix or an active matrix display grid. The active matrix LCD is also known as a thin film transistor (TFT) display. The passive matrix LCD has a grid of conductors with pixels located at each intersection in the grid. A current is sent across two conductors on the grid to control the light for any pixel. An active matrix has a transistor located at each pixel intersection, requiring less current to control the luminance of a pixel. For this reason, the current in an active matrix display can be switched on and off more frequently, improving the screen refresh time (your mouse will appear to move more smoothly across the screen, for example).A typical liquid crystal display will incorporate the LCD fluid (either TN, STN, HTN or F-STN) in a glass envelope with ITO coatings to the internal glass surfaces. The basic liquid crystal display, either statically driven or multiplexed, is frequently incorporated onto a PCB (Printed Circuit Board) with the LCD display driver hardware and often backlighting, LED EL, or CCFL.Liquid crystal displays do not suffer degradation over time, the LCD fluids always return to their normal state when a voltage is not applied. Temperature does affect liquid crystal displays however, with extreme low temperature causing the LCD to respond very slowly. The required bias voltage across the liquid crystal display also alters with ambient temperature.Some passive matrix liquid crystal displays have dual scanning, meaning that they scan the grid twice with current in the same time that it took for one scan in the original technology. However, active matrix is still a superior technology.Temperature does affect liquid crystal displays, however with extreme low temperature causing the LCD to respond very slowly. The required bias voltage across the liquid crystal display also alters with ambient temperature |
| LCD Panel |
Also called a projection panel, it is a data projector that accepts computer output and displays it on a transmissive liquid crystal screen that is placed on top of an overhead projector.Liquid crystal display systems are also available with their own light source. Such units generally provide the best quality, because the light and lenses are fine tuned to the built-in LCD screen. |
| Lead(s) |
The conductive trace(s) on the contact edge of the glass. |
| LED Backlight |
A form of backlighting for small to medium size LCDs that use surface mount LEDs on a substrate with a light diffuser over the top. In some cases LEDs are placed at each end of the module and light is directed into the center. |
| liquid crystal |
The compound found in liquid crystal displays. Liquid crystal reacts predictably when electrically stimulated. This makes it the ideal compound to turn LCD pixels "on" or "off." Liquid crystal is sometimes abbreviated as LC. |
| Liquid Crystal Fluid |
Has properties of both a fluid and solid. Consisting of rod shaped, bipolar molecules, which in the OFF state are capable of twisting polarized light. |
| luminance |
A measure of the brightness or luminous intensity of light, usually expressed in units of Candelas per square meter (cd/m2) or foot Lamberts. 1 fL = 3.426 cd/m2. |
| Lux |
A standard for measuring light, numbers provided by manufacturers usually do not provide necessary additional information to compare one product to another. |
| LVDS |
(Low Voltage Differential Signalling) A transmission method for sending digital information to a flat panel display. LVDS has been widely used in laptops because it enables fewer wires to be used between the motherboard and the panel. The technology is also used between the image scaler and the panel in many stand-alone flat panel displays. |
| Mac Compatibility |
The ability to offer at least one preset mode that will synchronize with a Macintosh computer. |
| Module |
An LCD glass connected to a PCB with drivers on board. It may also have controllers, temperature compensation circuits, or other features. |
| Mounting Solutions ( Arms ) |
For LCD Monitors designed in compliance with VESA Standard Physical Mounting Interface Standard (FPMPM), users may choose mounting solutions from professional arm manufacturers. |
| MPR-II |
Provides reduced electrostatic and electromagnetic emissions. MPR 1990, or MPR-II, is a standard defined to measure emissions from devices such as monitors. |
| Multiple Frequency Technology |
Automatically adjusts the monitor to the display card’s scanning frequency, thus displaying the resolution required. |
| Multiplex |
Using multiple backplanes (commons) in order to reduce the number of connections between the drivers and the LCD. |
| nanometer (nm) |
A unit of length equal to 10-9 meter. In light measurement, the wavelength of light is measured in nanometers. The portion of the spectrum that we perceive as visible light includes wavelengths from about 380 nm to 770 nm. |
| Native Resolution |
Unlike traditional CRTs that can display multiple resolutions, LCD displays are manufactured to best display a single resolution, known as the native resolution. While it may be possible to change the resolution of an LCD (depending on the video card and software used with the LCD), setting the resolution to something other than the native resolution will result in a stretched image, a blurry image, or no image on the screen at all. This is typically expressed as the number of pixels in a line by the number of lines, e.g. 1024x768. The native resolution may also be expressed in megapixels, which is calculated by multiplying pixels per line by total lines. |
| Negative Image |
The viewing area is a dark color in the OFF state. This condition is achieved by having both front and rear polarizers in the same axis. In this mode, light passes through the energized areas. Some type of backlight must be used in order to effectively view the information. |
| NEMA |
(National Electrical Manufacturers Association) develops standards for the electrical manufacturing industry. |
| Nit |
A measure of luminance equal to 1 candela per square meter (1 cd/m2 or 0.292 ftL). Higher numbers indicate brighter displays. |
| normally black |
A twisted nematic LCD design where the backlight is blocked when pixels are in the unselected state. Therefore, when no voltage is applied, the screen is black. |
| normally white |
A twisted nematic LCD design where light is transmitted when pixels are in the unselected state. Therefore, when no voltage is applied, the screen is white. |
| NTSC |
The United States broadcast standard for video and broadcasting. An older standard and lower resolution than systems used in most of the world. |
| NUTEK |
(The Swedish Board for Technical Accreditation). This council produces specifications for automatic power-down and power consumption during normal operation. |
| OSD |
(On-Screen Display) An on-screen control panel for adjusting monitors and TVs. The OSD is used for contrast, brightness, horizontal and vertical positioning and other monitor adjustments. |
| PAL |
A European and international broadcast standard for video and broadcasting. Higher resolution than NTSC. |
| Panel |
The predecessor to today's projectors, (some are still available) they a thin (under 2") devices typically 10 x 14 inches. All panels are of the LCD variety. They lack their own light source, and instead, sit on top of a overhead projector (OHP). Although panels are light (5-8LB.), even on specially designed, extremely bright, overhead projectors, they produce dim images useable only in darkened rooms on small screens.
Panels survive as the entry level products in every catagory. Typically the most expensive panel in a given resolution, sells for less than the least expensive projector. More expensive panels sell moderately well in SVGA and XGA resolutions due to the tremendous difference in prices between panels and projectors in those resolutions. |
| Passive Matrix Display |
A common type of flat panel display consisting of a grid of horizontal and vertical wires. At the intersection of each grid is an LCD (Liquid Crystal Display) element which constitutes a single pixel, either letting light through or blocking it.A higher quality and more expensive type of display, called an active matrix display, uses a transistor to control each pixel. In the mid 1990's, it appeared that passive matrix displays would eventually become extinct due to the higher quality of active matrix displays. However, the high cost of producing active matrix displays and new technologies such as DSTN, CSTN and HPA that improve passive matrix displays, have caused passive matrix displays to make a surprising comeback. |
| Passive Matrix LCD |
The original LCDs, these are controlled by a single processing system, for the whole screen, unlike active and poly-si, which have descrete circuits for each "pixel." This results in a panel with terrible color dynamics and contrast (typically 15:1). They are also incredibly slow: On passive laptop computers, the cursor (or anything else) moving on the screen, goes invisible until you stop moving it (submarining) Only one or two projectors use any type of passive matrix display. |
| persistence |
The time it takes for the visible glow of a CRT's phosphor to darken after the scanning electron beam is removed. A long persistence means less flicker, but may create smearing when images are in motion. |
| phosphor |
The coating on the inside of CRTs. Phosphor glows when struck with electrons. Images appear on a CRT by controlled scanning of an electron beam. |
| Pitch |
Is the center to center dimension of adjacent conductive traces, dots, or connector holes. |
| Pivotal Screen |
Monitors that allow users to swivel the display 90 degrees and place the screen image in portrait orientation.
Color systems use a red, green and blue dot per pixel, each of which is energized to different intensities, creating a range of colors perceived as the mixture of these dots. Black is all three dots dark, white is all dots light. |
| Pixel |
Picture element (see Dot/Pixel). Pixels are tiny picture elements comprised of three subpixels (one red, one green, and one blue.) Although a single pixel displays one color, collectively those pixels create a complete image recognizable by the human eye. A single LCD consists of thousands, even millions of pixels. |
| Pixel Anomaly |
A pixel anomaly is a pixel that displays only one color (white, black, red, green, or blue.) These are commonly referred to as "stuck" or "void" pixels. If a pixel on an LCD appears to be stuck on one color, it will sometimes come back to life by gently massaging the pixel and the area surrounding it in a circular pattern. (For obvious reasons, pixel massage will not work on a CRT.) A small number of pixel anomalies are considered normal, or at least inevitable, on LCDs. The number of pixel anomalies it takes for a display to be considered defective varies by hardware manufacturer. |
| Pixel Clock Speed |
The frequency or speed at which individual pixels (picture elements) in an image are written to the screen. The higher the pixel clock speed, the less likely there will be flicker. |
| polarizer |
A light filter which only allows light waves of a certain rotation through. Polarized material with perpendicular filtering is used in LCDs to enclose the liquid crystal. The liquid crystal is then used as the medium which twists the light waves 90° in order to allow the light to pass through or not. |
| Polarizers |
Are made of a polymer acetate with iodide molecules incorporated in the material. The molecules are arranged to only allow scattered light to enter in one plane/axis. Twisted nematic LCDs require two polarizers, one on the front and one on the back. |
| Poly Si (Silicate) LCD |
The "hot" LCD technology for the top of the line LCD projectors. Poly-Sci is typically 3 separate layers of LCDs, one each for Red, Green and Blue. This results in increased color dynamics, with contrast ratios around 200:1. Poli-Si technology is also a bit faster than the Active Matrix TFT, for smooth video and multimedia. |
| Portrait Orientation Display |
A page or screen orientation that is taller than it is wide. Monitors that allow users to swivel the display 90 degrees and place the screen image in portrait orientation. |
| Positive Image |
Active elements, when energized, appear dark in color against a light background (non-energized); i.e., reflective, transflective, transmissive, (positive) inverse image. |
| RCF (Retardation Control Film) |
A thin (100 microns thick) piece of material laminated to the rear polarizer. Function is to change normal blue colored dots to black. Used on supertwist graphic modules with a CFL light source. Commonly referred to as black and white. |
| Reflective |
Typically a smooth silver/gray piece of polished aluminum foil bonded to the rear polarizer. Reflects the incoming ambient light. Note: Backlighting can not be used with a reflective type LCD. |
| Refresh Rate |
Applicable to CRTs but not LCDs, refresh rate equals the number of times per second that the electron gun redraws the image on the screen. For example, if a CRT's refresh rate is set to 60 Hz, the screen image will be redrawn 60 times a second. Low refresh rates will cause the image to flicker, resulting in eye strain or other problems. For this reason, refresh rates on CRTs should be set as high as possible |
| Resolution |
The number of pixels displayed on a monitor. Resolution is defined by listing the number of pixels in each horizontal row by the number of pixels in each vertical column (i.e. 640x480, 800x600, etc.) |
| Response Time |
This figure indicates how quickly an LCD panel can display a change in the brightness of the screen image. It is calculated as the sum of the times needed for the image to change from 10% to 90% of its maximum brightness, and from 90% to 10%. Faster response times allow a smoother display of rapidly-changing screen images, such as real-time video. |
| Response Time (T OFF) |
Total of delay time (Td off) and rise time Tr. |
| Response Time (T ON) |
Total of rise time Tr and delay time Td on: Time interval between 10%(on) to 90%(on). |
| 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. |
| Rotation |
Swiveling the display 90 degrees and place the screen image in portrait/ landscape orientation. |
| Saturation Voltage |
RMS voltage required to turn fluid to 90%(on). |
| Scaling |
An operation performed by a digital signal processor to fill the screen with an image not being displayed in the native resolution of the LCD panel. |
| Scan Rate |
Indicates the speed, measured in kilohertz, at which a single horizontal line is drawn on the screen. Higher scan rates are needed to provide sharper, crisper images at higher resolutions; also called horizontal frequency. |
| SECAM |
A French and international broadcast standard for video and broadcasting. Higher resolution than NTSC. |
| Segment |
An active element of a digit (i.e., typically numeric digits have 7 segments and alpha/numeric digits can have 14 or 16 segments). |
| SIL (Single-In-Line) |
An LCD module having a single row of connection holes, LCD glass having a single contact edge. |
| Stripe Pitch |
A measurement of distance between the centers of two same-color stripes that make up a screen image. The closer the stripes, the smaller the stripe pitch, and the sharper the image. |
| Stuck Pixel |
See Pixel Anomaly |
| sub-pixel |
Each pixel is made up of three independently controlled sub-pixels. In a color display these sub-pixels have red, green, or blue color filters. Or, in the case of a grayscale display, each sub-pixel will have a clear transparent filter, allowing the full grayscale range to be displayed. Each sub-pixel is capable of generating different intensities, creating a range of colors or grayscale values, which is perceived as a mixture of each sub-pixel value. |
| subtractive primaries |
The process colors cyan, magenta, and yellow. Each absorbs or subtracts its complementary color—red, green, or blue—from the light reflecting off the paper. |
| SuperClearMVA (Multi-Domain Vertical Alignment) |
Combines SuperClear screen technology digital with a liquid crystal technology in which each subpixel is subdivided into four regions in which the liquid crystal molecules align at angles to each other. The advantages of MVA are wider viewing angles and faster video response than TN or IPS. |
| Supertwisted Nematic (STN) |
An improved twisted nematic fluid (200° twist or greater) which has better contrast and optimum viewing range than standard twisted nematic (90°). Acronyms - SBE, New TN; NTN; SNTN. |
| SXGA Resolution |
SXGA refers to a monitor resolution of 1280 x 1024 pixel display, regardless of the number of colors available. This is the next highest resolution above XGA. What makes SXGA unusual is that its standard ratio is 5:4, while VGA, SVGA, XGA, and UXGA are all the traditional 4:3 ratio found on computer monitors. What resolutions are higher? UXGA and QXGA. |
| TAB (Tape Automated Bonding) |
LCD driver or controller electronics are encapsulated in a thin, hard bubble package, of which the drive leads extend from the bubble package on a thin plastic substrate. The adhesive along the edges is used to attach the TAB to the LCD glass and/or PCB. |
| TFT - Thin Film Transistor |
Definition 1:Abbreviation of thin film transistor, a type of LCD (Liquid Crystal Display) flat panel display screen, in which each pixel is controlled by, from one to four transistors. The TFT technology provides the best resolution of all the flat penal techniques, but it is also the most expensive. TFT screens are sometimes called active matrix LCDs.Definition 2:This term typically refers to active matrix screens on laptop computers. Active matrix LCD (Liquid Crystal Display) provides a sharper screen display and broader viewing angle than passive matrix screens. |
| Threshold Voltage |
RMS voltage required to turn fluid to 10% ON. |
| Tilt and Swivel |
The ability for the monitor head to either move up and down (tilt) or side to side (swivel). |
| Touch Screen |
A display screen that is sensitive to the touch of a finger or stylus. Touch screens are very resistant to harsh environments where keyboards might eventually fail. They are often used with custom-designed applications so that the on-screen buttons are large enough to be pressed with the finger. Applications are typically very specialized and greatly simplified so they can be used by anyone. However, touch screens are also very popular on PDAs and full-size computers with standard applications, where a stylus is required for precise interaction with screen objects.
There are two primary technologies used for touch screens and both use a clear glass panel overlaid onto the CRT or LCD screen. The resistive method is completely pressure sensitive. It uses a plastic layer on top of a metallic-coated glass layer, separated by spacers. When pressed, it shunts the current in the glass panel, and the x-y coordinates pick up the location on the screen.
The capacitive method uses a metallic coated glass panel, but without the plastic overlay. It senses the change in current from the charge in the your finger or a stylus. The stylus used with this technique must emit a charge and is thus wired to the computer. |
| Transflective |
A type of backing which is bonded to the rear polarizer. Enables light to pass through the back, as well as reflecting light from the front. |
| Transmissive |
A type of LCD which does not have a reflector or transflector laminated to the rear polarizer. A backlight must be used with this type of LCD configuration. Most common is transmissive negative image. |
| Transparent |
Adjective to describe a material that transmits light without diffusion or scattering. |
| True Color |
A PC term for 24 bit color (16.7 million colors - 256 shades each of Red, Green, and Blue). |
| Twisted Nematic (TN) |
A type of liquid crystal in which the alignment surface, and therefore the liquid crystal molecules, is oriented 90 degrees from each surface of glass. |
| UL/ULC |
(Underwriters Laboratory). A non-profit safety organization in the U.S. that inspects and certifies the products sold in the U.S. and Canada for their safety standards. |
| UXGA Resolution |
A rarely seen resolution - boasting 2048x1536. This 4:3 ratio is techincally slightly higher than the highest HDTV resolution (1920x1080). |
| Vertical Frequency |
Also called "refresh rate," it is the number of times an entire display screen is refreshed, or redrawn, per second. Measured in Hertz, display systems typically range from 56Hz to well over 100Hz. A minimum of 70Hz is recommended to help prevent eye strain. |
| VESA |
Video Electronic Standards Association. A group made up from the video electronics industry to review proposals and develop standards to promote uniformity and economies of scale in the video electronics industry. |
| VESA DPMS |
(VESA Display Power Management Signaling) A VESA standard for signaling the monitor to switch into energy conservation modes. It provides for two low energy modes: standby and suspend. |
| VGA – Video Graphics Array |
Display standard developed by IBM. Uses analog signal |
| VGA Resolution |
Today VGA resolution normally refers to a 640 x 480 pixel display, regardless of the number of colors available. Originally VGA was 640 x 480 16 colors. Throughout this website it will refer to 640 x480 resolution. |
| Video Response (response time) |
The time it takes to turn a pixel from OFF to ON to OFF again. A low number is desirable to display moving images without ghosting. |
| Video Standards |
A variety of broadcast and video standards, including NTSC, PAL, SECAM, plus S-VHS (video only) 3/4" (video only), etc. Standards like NTSC, PAL and SECAM, are often revised, so you might see something like NTSC 3.58, PAL 4.43 etc. The lack of numbers typically means little. Since most projectors are around for less than two years, projectors capabilities change much faster than the broadcast industry. If you are buying a discontinued or used system, and will be using outside North America, you may which to confirm compatibility with us. |
| Viewable area (viewable image size) |
CRT image size is advertised as the diagonal measure of the glass in the display (15", 17", etc.) However, the viewable area, or the size of the image a monitor can actually display, is usually one to two inches less than the advertised size. LCD image size is usually identical to what is advertised, as the physical picture tube border present on CRTs (the space between the viewable area on the CRT and the plastic chassis) is not present on LCD displays. |
| Viewing Angle |
A cone perpendicular to the LCD in which the contrast ratio exceeds 10. |
| Viewing Area |
The dimensions measured from the inside perimeter of the LCD bezel or LCD glass epoxy seal. The viewing area defines actual area that can be illuminated when the entire screen is turned ON (white). |
| Workstation Resolutions |
Generally a number of different resolutions, higher than 1024 x 768. Most widely used: 1280 x 1024, 1152 x 900. Also 1600 x 1200.
Some workstations can be set to the lower resolution of 1024 x 768, but are not normally operated there. |
| X |
(1) One of the three CIE tristimulus values; the red primary. (2) Spectral color matching functions of the CIE standard observer used for calculating the X tristimulus value. (3) One of the CIE chromaticity coordinates calculated as the fraction of the sum of the three tristimulus values attributable to the X value. |
| XGA Resolution |
A resolution of 1024x 768, this is now the most common used resolution on laptops and desktops, and as such has replaced SVGA and the current "standard". Higher resolutions are available as well, including SXGA and UXGA.
XGA is likely to remain the standard on laptops for some time as higher resolution like SXGA makes for extremely small type, even on the largest laptops such as 15" display Dell models. |
| Y |
(1) One of the three CIE tristimulus values, equal to the luminous reflectance or transmittance; the green primary. (2) Spectral color matching function of the CIE standard observer used for calculating Y tristimulus value. (3) One of the CIE chromaticity coordinates calculated as the fraction of the sum of the three tristimulus values, attributable to the Y value. |
| Z |
(1) One of the three CIE tristimulus values; the blue primary. (2) Spectral color matching function of the CIE standard observer used for calculating the Z tristimulus value. (3) One of the CIE chromaticity coordinates calculated as the fraction of the sum of the three tristimulus values attributable to the Z value. |
| Zebra Connector |
Same as- Elastomer Connector which is a strip of silicone rubber made up of sequentially spaced conductive and non-conductive material. This is the most common connection method for LCD modules. |
® LCD and LED Glossary