FAQ: Technical Terms regarding Screens
Active Area- Effective Area In the viewing area of the LCD glass, the dimensions of the perimeter of the conductive area.
Active Matrix Display- A type of display which uses Thin-Film Transistors (TFT) to control each pixel individually. Active Matrix Displays offer higher contrast ratios, wider viewing angles, and faster response times than Passive Matrix Displays.
Aperture Ratio- The actual light-transmitting area against the theoretical sub-pixel size calculated with active area and resolution.
Aspect Ratio- The relationship of width and height. When an image is displayed on different screens, the aspect ratio must be kept the same to avoid 'stretching' in either the vertical or horizontal direction. For most current monitors, this ratio is 4:3. For HDTV, the ratio will be 16:9 or 16:10.
Backlight - Some LCD displays are illuminated by the use of separate light sources or backlight that are built into the unit behind the LCD panel.
Bezel- A frame of plastic or metal, fitting over the LCD glass, to protect the edges of the glass, ESD(Electro Static Discharge), and to reinforce LCD structure.
Brightness- The attribute of visual perception in accordance with which an area appears to emit more of less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness.)
CCFL Cold Cathode Backlight- A type of fluorescent backlighting or edge lighting.
Cell Gap- The space containing liquid crystal fluid between the two pieces of glass.
COG CHIP-ON-GLASS- A new technology that mounts the LCD driver to the contact edge of the LCD glass.
Contrast Ratio- The difference in luminance between all-white divided by the brightness of an all black.
Color Temperature- Measured in degrees Kelvin, reference to color temperature provides a standard for defining standard colors emitted from computer displays. 6500K is close to the European TV standard, and close to the white color under the sun at noon.
Cross Talk- A phenomenon occurring when voltage from an energized element leaks to an adjacent OFF element and turns the adjacent element partially ON, making them slightly visible.
Digital Visual Interface (DVI)- A digital flat panel interface introduced by the Digital Display Working Group (DDWG). Although other interfaces have been introduced, DVI is expected to become the industry standard.
Display Data Channel (DDC)- A communication channel for the transmission of information between the display monitor and the PC that allows for automatic configuration of the hardware. In other words, "Plug and Play" compatibility.
Dot Clock/Dot Frequency- The frequency with which dots (or pixels) are illuminated on the screen; how quickly a single dot can be produced on the screen.
A general formula for calculating the dot frequency is: H x V x refresh-rate x 1.25( to1.3)
Dot Pitch- The distance between one pixel to adjacent pixel (not sub pixel). Dot pitch gives a general idea of the monitor's ability to produce sharp images.
GHOSTING- Refer to "Cross Talk"
Higher color saturation- makes the display more vivid and increases the image quality.
With CMO's newly developed high color saturation technology, the color saturation of LCD could be increased even reach NTSC 100%, which is 1.4 times of that of current CRT (sRGB specification, same as the HDTV specification). more info
Inverter- Converts DC to AC at a high frequency & voltage, and powers fluorescent lamps.
IPS - In-Plane Switching. Single domain IPS has slight color shifts under certain viewing angle, but Dual domain IPS has less color shifts.
Liquid Crystal Display (LCD)- A glass panel display that electronically controls the light passing it using liquid crystal.
LVDS- Low Voltage Differential Signaling.
Module- An LCD which includes a PCB, driver electronics, bezel, and possibly a backlight.
Polarize- A stretched polymer which transmits light in only one axis. A typical display has polarizes on the front and back.
Refresh Rate- The frequency with which the entire image on the screen is redrawn. The refresh rate is measured in hertz, therefore, a refresh rate of 60 Hz, means the image is redrawn 60 times per second.
Response time- Time interval between 10%(on) to 90%(on) or 90%(off) to 10%(off) of brightness.
RGB- The initials of the colors Red, Green and Blue. Any color can be composed with the combination of the three colors.
sRGB- a color space defined by Microsoft and Hewlett-Packard with the aim of color matching between applications and hardware devices such as monitors, scanners, printers, and digital cameras.
TAB Tape Automated Bonding- LCD driver or controller electronics are encapsulated in a thin, film like package, with metal leads extension from the IC chips.
TFT- Thin Film Transistor: a type of LCD flat-panel display screen, in which each pixel is controlled by from one to four transistors. TFT technology provides the best resolution of all the current flat-panel techniques. TFT screens are sometimes called active-matrix LCDs.
Twisted Nematic (TN)- A type of liquid crystal where the alignment surface, and therefore the liquid crystal molecules, is oriented 90 degrees from each surface of glass.
Viewing Angle- A cone perpendicular to the LCD in which minimum contrast can be seen.