A definition of various terms and initials used throughout this website.
| Active |
A display technique by which each pixel is driven by a thin film transistor in the LCD glass. |
| Aspect Ratio |
Screen shape defined by the ratio of width to height. |
| Active Area/Effective Area |
Perimeter dimensions of the conductive area, within the viewing area of the LCD glass. |
| Active Matrix TFT |
Type of LCD, used in most laptops, and most LCD panels and projectors. A typical active matrix TFT displays are noted for their quick response time and their ability to display full motion video and animations without image ghosting. |
| Alignment Layer |
A layer and/or surface treatment applied to the boundary of a liquid crystal cell to induce a particular director orientation. For example, a layer of polyimide buffed in one direction induces alignment parallel to the buffing direction. |
| Amorphous |
Irregular; having no discernible order or shape. In the context of solids, the molecules are randomly arranged, as in glass, rather than periodically arranged, as in a crystalline material. |
| Anisotropic |
Having properties which vary depending on the direction of measurement. In liquid crystals, this is due to the alignment and the shape of the molecules. |
| Annunciator |
An active element, such as a symbol, word, or phrase. |
| Aspect Ratio |
The ratio of the width of the display to the height of the display eg VGA 640 x 480 is a 4:3 format (480 x 4/3 = 640). |
| ASV: |
Advanced Super V technology from Sharp designed to enhance the viewing angle.
|
| Bezel |
A metal or plastic frame which fits over the LCD glass. The bezel acts as a pressure device, compressing the elastomer connector between the LCD glass and PCB. |
| Brightness |
Light intensity of the display measured in candela per square metre (cd/m2). |
| Brightness |
The attribute of visual perception in accordance with which an area appears to emit more or less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness). |
| Buffing |
To give the inner glass surfaces of a liquid crystal cell a texture so as to align the liquid crystal molecules in a certain direction parallel to the surfaces. |
| CCFL |
Cold Cathode Fluorescent Lamp (also known as CFL). (Click here for more information). |
| COB |
Chip On Board. |
| COG |
Chip On Glass. |
| Contrast |
The ratio between the screen’s brightest pixels and its darkest pixels. |
| CSTN |
Colour Super Twisted Nematic (also known as Colour STN). |
| Cell Gap |
The spacing between the two pieces of glass. This space contains the liquid crystal fluid. |
| Chip on Board (COB) |
The LCD driver is formatted into an area on the PCB. Electrical connections are made by micro diameter gold wires. |
| Chip on Glass (COG) |
Recent technology development, where the LCD driver is mounted directly on the LCD glass substrate. |
| Chip on Flex (COF) |
The LCD driver is incorporated into a flex connector, which is attached to the contact edge of the LCD glass. |
Cold Cathode Fluorescent Lamp (CCFL)
|
A type of fluorescent backlighting or edge lighting. Used in small, medium and large size graphic LCD modules. |
| Colour Temperature |
A method of measuring the "whiteness" of a light source. |
| Common Interface Format (CIF) |
Developed to support video conferencing. CIF has an active resolution of 352 x 288 and a refresh rate of 29.97 frames per second. Quarter CIF (QCIF) has a resolution of 144 x 176. QCIF+ has a resolution of 220 x 176. High definition CIF (HDCIF) is used for HDTV production and distribution having a resolution of 1920 x 1080. |
| 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. |
| Component Video |
A method of delivering quality video (RGB) in a format that contains all the components of the original image. These components are referred to as luma and chroma and are defined as Y'Pb'Pr' for analog component and Y'Cb'Cr' for digital component. Component video is available on some DVD players and projectors. |
| Composite Video |
The combined picture signal, including vertical and horizontal blanking and synchronising signals. |
| 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 ratio |
The difference in luminance between the unselected area and the selected area. |
| 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. |
| Digital Video Interface (DVI) |
A standard that defines the digital interface between digital devices such as projectors and personal computers. For devices that support DVI, a digital to digital connection can be made that eliminates the conversion to analog and thereby delivers an unblemished image. |
| Direct/Static Drive |
Each conductive lead on the contact edge, connects to one segment or annunciator. |
| Dot/Pixel |
Typically a rectangular active element, when combined together in a matrix, forms a character, symbol or dot matrix. |
| Dot Matrix |
A group of dots/pixels forming a matrix. |
| Duty Ratio |
1/N, where N equals the number of energised or unenergized rows selected by one complete cycle. |
| EL |
Electro-Luminescent backlight. (Click here for more information). |
| Elastomers |
A class of polymers that have some degree of cross linking and are rubbery. Elastomers possess memory, that is, they return to their original shape after a stress is applied. |
| 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 aluminium reflector. When AC voltage is applied to the electrodes, the electrons collide with the light emission core. The energy given off is light. |
| FSTN |
Film compensated Super Twisted Nematic (also known as Film-STN). |
| FFC |
Flat Flexible Cable. |
| 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. |
| Ghosting |
A phenomenon which occurs when voltage from an energised element leaks to an adjacent OFF element and turns the adjacent element partially ON. |
| HIFAS |
High Frequency Amplitude Selection. |
| HTN |
High Twisted Nematic. |
| 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. |
| IPS |
In-Plane Switching technology from Hitachi designed to enhance the viewing angle (also known as Super TFT).
|
| Inverter (DC to AC) |
Used to power electroluminescent lamps. Converts DC to AC voltage at a high frequency 300Hz ~1khz. |
| Inverse/Reverse Image |
Used exclusively on negative image graphic displays (transmissive negative). With EL or cold cathode backlight where the background is energised and the information to be displayed remains static or the same colour as the polariser in the OFF state. This is achieved by inverting the signal of the data lines before going to the LCD module. |
| 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. |
| LCD |
Liquid Crystal Display. |
| LED |
Light Emitting Diode backlight. (Click here for more information). |
| LVDS |
Low Voltage Differential Signalling. |
| 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 centre. |
| 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 polarised light. |
| Module |
Consists of LCD (glass) connected to a PCB with drivers on board. Controllers, temperature compensation circuits, etc., are optional. |
| Multiplex |
Using multiple backplanes (commons) in order to reduce the number of connections between the drivers and the LCD. |
| Negative Mode |
Light characters on a dark background Display. |
| Negative Image |
The viewing area is a dark colour in the OFF state. This condition is achieved by having both front and rear polarisers in the same axis. In this mode, light passes through the energised areas. Some type of backlight must be used in order to effectively view the information. |
| Passive |
A display technique by which the rows and columns of pixels are multiplexed. |
| Positive Mode |
Dark characters on a light background Display. |
| PanelLink |
An all digital interface used to transmit computer video from a PC/Notebook to a projector. Supports resolutions from 640x480(VGA) up to 1600x1200(UXGA). |
| Persistence |
The amount of time a phosphor or diode pixel stays lit after current has been applied to it. A pixel's persistence is what allows an image to remain on the screen between screen refreshes. Screens with short persistence may show flicker, while thiose with long persistence may show ghosting. |
| Positive Image |
Active elements, when energised, appear dark in colour against a light background (non-energised); i.e., reflective, transflective, transmissive, (positive) inverse image. |
| QVGA |
Quarter VGA (offers a screen resolution of 320 x 240). (Click here for more information). |
| Reflective |
Viewing mode which uses ambient light only to provide display illumination. (Click here for more information). |
| Resolution |
Pixel count e.g. 320 x 240. |
| Reversible |
A feature which enables a display to be switched from positive to negative mode. |
| Retardation Film |
A thin (100 microns thick) piece of material laminated to the rear polariser. Function is to change normal blue coloured 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/grey piece of polished aluminium foil bonded to the rear polariser. Reflects the incoming ambient light. Note: Backlighting can not be used with a reflective type LCD. |
| Response Time (Toff) |
Total of delay time (Td off) and rise time Tr. |
| Response Time (Ton) |
Total of rise time Tr and delay time Td on: Time interval between 10%(on) to 90%(on). |
| STN |
Super Twisted Nematic. |
| SVGA |
Super VGA (offers a screen resolution of 800 x 600). (Click here for more information). |
| Supply Voltage |
Logic supply voltage which on some modules may be separate from the LCD supply. |
| Saturation Voltage |
RMS voltage required to turn fluid to 90% (on). |
| 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). |
| Strong 2 |
High durability LCDs from Sharp that are resistant to extremes of temperature, shocks and vibration. |
| 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. |
| TAB |
Chip on Tab. |
| TCP |
Tape Carrier Package. |
| TFT |
Thin Film Transistor. |
| TN |
Twisted Nematic. |
| Transflective |
Viewing mode which uses ambient light or backlighting to provide display illumination. (Click here for more information). |
| Transmissive |
Viewing mode which uses backlighting only to provide display illumination. (Click here for more information). |
| Tape Automated Bonding (TAB) |
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. |
| Threshold Voltage |
RMS voltage required to turn fluid to 10% (on). |
| Transflective |
A type of backing which is bonded to the rear polariser. 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 polariser. A backlight must be used with this type of LCD configuration. Most common is transmissive negative image. |
| Twisted Nematic (TN) |
A type of liquid crystal whereas the alignment surface and therefore the LC molecules are oriented 90° from each surface of glass. |
| UL |
End products can be Listed by Underwriters Laboratories for expected safety concerns. |
| VGA |
Video Graphics Array (offers a screen resolution of 640 x 480). (Click here for more information). |
| Viewing Angle |
The maximum angle at which a display can be viewed with acceptable definition. |
| Viewing Direction |
Displays that are best viewed at a direction from below the centre of the screen are defined as 6 o’clock. Displays best viewed above the centre are defined as 12 o’clock. |
| Viewing Angle |
A cone perpendicular to the LCD in which minimum contrast ratio can be seen. |
| Viewing Area |
The dimensions measured from the inside perimeter of the LCD bezel or LCD glass epoxy seal. |
| WVGA |
Wide VGA (offers a screen resolution of 800 x 480). (Click here for more information). |
| WXGA |
Wide Extended Graphics Arrays (offers a screen resolution of 1280 x 800). (Click here for more information). |
| XVGA |
Extended VGA (offers a screen resolution of 1024 x 768). (Click here for more information). |
| Zebra Connector |
See Elastomer Connector. |
