Active matrix liquid crystal
display. A display technology that uses a TFT (thin Film Transistor)
switch at each pixel to create high resolution and fast response
times. Displays based on this technology range from as small
as 1" diagonal up to 56" diagonal (greater than 40" are prototypes).
ASP
Average selling price
Backlight
Light source for an LCD, located
behind the panel (cold cathode fluorescent (CCFL), External
Electrode Fluorescent (EEFL) hot cathode fluorescent (HCFL),
Electroluminescent (EL) or LED)
Brightness
Brightness is purely a psycho-physiological
attribute; the subjective response to electromagnetic energy
that occurs when the human eye has adapted to a particular radiation
level. See luminance for quantifiable measure.
CAGR
Compound annual growth rate
Cd/sq metre
A candela/sq m is the unit used
to measure Luminance. 1 candela per square metre is the luminance
of one candle power measured one metre away over a one square
metre area, and is equal to 1 NIT
Collimation
The optical process whereby a
virtual image is produced at or near infinity. The light rays
received at the eye point are then parallel. The collimation
angle is generally defined as the angle at which the light intensity
is 50% of the maximum.
Colour
Colour can be described by three
measurable factors: luminance, hue and saturation. The CIE chromaticity
system allows any colour visible to the eye to be characterized
by a pair of co-ordinates (x and y) within an area bounded by
the limits of colours perceived by the eye.
Contrast ratio
The ratio of full white to full
black luminance at a stated level of illumination. If no illumination
level is stated it is measured under dark room conditions.
CRT
Cathode ray tube, the previous
de factor standard technology used in television sets and desktop
computer monitors. It is a vacuum tube where an image is generated
from an electron beam scanned across the surface of a phosphor
which generates light. CRT's are deep and heavy compared to
flat panel displays.
Direct view displays
A display where the viewer focuses
directly on the image plane.
DLP
Digital Light Projection - projection
display using a MEMs device
DVD
Digital Versatile Disk. The standard
digital recording format for home cinema. 720x480 in Europe.
EL
Electroluminescent display. This
is made of a layer of a solid state material which emits light
under an electric field (phosphor materials). EL can be used
as either a backlighting source for LCD displays or as a graphic
display technology by itself.
Emissive
Displays that inherently create
light such as CRT, FED, plasma, EL and OLED. These displays
do not need a separate backlight to provide light for the image.
FED
Field emission display. Emissive
display in a flat panel vacuum envelope that uses electrons
emitted from an area source to excite a phosphor screen to emit
light. Known sometimes as a Flat CRT.
Format
The term defining the pixel matrix
on a display; i.e. 640 x 480, 1024 x 768, etc.
FPD
Flat panel display. Can be used
to refer to any of a number of "flat" display technologies including
LCD, plasma, FED etc.
Greyscale
Greyscale describes the ability
of a display to be in a state between full ON and full OFF.
Each of these definable states is a "grey level." The greyscale
is composed of the number of grey levels.
HDTV
High definition television. A
range of standard formats for widescreen displays including
1280x720 (720p) to a maximum of 1920x1080 (1080p). Primarily
for digital television and home cinema.
Hue
Hue is the dominant wavelength
of colour as subjectively perceived by the human eye.
Illuminance
The amount of visible radiation
incident upon a specified unit area. The preferred unit is the
lux (lumen per sq.m.) . The footcandle (lumen per square foot)
is widely used in the USA and is converted to lux by multiplying
by 10.764.
Immersive
A term applied to visual display
systems in which the displayed scene gives the impression of
surrounding (or "immersing") the observer. In the extreme immersive
displays are used in domes or wrap-around screens to provide
very wide fields of view and to enhance realism for simulators
etc.
ITrans®
Screen Technology's technology
for unlimited seamless tiling of displays using non-imaging
optics
LCD (Liquid Crystal
Display)
The commonest type of flat panel
display used in a wide range of electronic devices such as digital
watches, phones, PDAs, notebook computers, monitors and television
sets. LCDs are made of two sheets of glass sandwiching a thin
layer of a liquid crystal material. The inner surfaces of the
glass have conductive electrodes which allow an electric field
to be applied to the liquid crystal material to change the optical
properties. Most LCDs have sheet polarisers laminated to the
glass surfaces which make the optical effect visible. Each pixel
operates as a shutter, either allowing light to pass or blocking
it. The LCD is sometimes known as the LCD glass.
LCD module
An LCD module is a sub system
consisting of the LCD, backlight, row and column drivers, controller,
and sometimes temperature compensation circuitry. The electronics
may be mounted on rigid or flexible PCB (TAB- Tape automated
bonding) bonded to the LCD or some of it may be bonded directly
onto the glass (CoG - Chip on Glass).
LED
Light emitting diode
LED backlight
A backlight for LCD panels that
uses an LED light source. The light from the LED is either diffused
from direct illumination or directed through a light pipe from
side illumination.
Liquid crystal fluid
A LC fluid has some of the properties
of a fluid and some of an anisotropic crystalline solid. The
LC is made up of long rod shaped organic molecules, which are
in a fluid anisotropic state over a range of at least their
storage temperature range. The molecules have a dielectic anisotropy,
which means that they move to align in a particular direction
under the influence of an electric field.
Lumen
The standard unit for measurement
of luminous flux - a measure of light flux
Luminance
The objective measurement of
brightness in the displayed scene. The standard unit is cd/sq.m.
Sometimes known as a Nit. In the USA the footlambert (fL) is
used (3.426 cd/sq.m to 1 fL) c
Luminous flux
Measured as the Lumen, a unit
of photometric (related to the eye) power.
Luminous intensity
The total visible light from
a source. This is the fundamental unit for photometric measurements,
the candela (lumen per steradian (solid angle))
MEM
Micro-engineered mechanical device.
In the displays field these devices are usually field addressable
micro-mirrors built onto Silicon chips.
OLED
Organic light emitting diode.
Display technology that can be used with polymer substrates.
Limited production to date because of short product lifetimes
(less than 10,000 hours). The biggest challenge is achieving
long time time and colour matched lifetime for full colour displays
Organic EL
Organic electroluminescent. An
analogue to the EL type display in which the active material
is organic.
Passive matrix LCDs
"Passive matrix" refers to the
type of LCDs that have no active or controlling element inside
the display cell. The display is controlled by row and column
drive lines from the outside of the display. They tend to have
lower resolution, slower switching times and poorer viewing
angles than AMLCDs.
PDP (Plasma Display
panel)
Emissive flat panel display technology
that uses a gas plasma to excite phosphors to glow. Used for
large-size displays (typically 42" diagonal and up). These displays
have sufficient luminance for indoor use and are best suited
for video. Many problems have been encountered with image burn
in in the field when used for information.
Pixel
Abbreviation for "picture element,"
a pixel is the smallest resolvable spatial information element
on a display screen. It consists of a single triad of dots (red,
green and blue) for most displays
PLLCD
Photo-luminescent LCD
Rear projection
displays
These have folded projection
optics and a mirror to project the image from a source (CRT,
DLP or LCD) onto the back of an integral viewing screen
Resolution
Best measured in Mpixels (million
pixels). The number of pixels available for information display.
More pixels (higher resolution) enables finer details to be
displayed and generally results in a better image quality.
RGB
Short for red, green, blue.
Saturation
Saturation is the degree to which
the hue of the colour is undiluted by its complementary colour
to form white.
Sub-Pixel
A sub-portion of a pixel showing
only one of the primary colours of light - red, green or blue.
Super VGA (SVGA)
A graphics standard of 800 dots
by 600 lines.
Uniformity
Uniformity or the lack thereof
is the gradual change of luminance and/or chrominance (colour)
across the face of the display.
VGA
IBM's Video Graphics Array that
includes the following resolutions: 320x200, 640x200, 640x480,
320x400, 640x350, 720x350, 360x400, 640x400, 720x400
Viewing angle
The angular range over which
the defined minimum contrast for the LCD is exceeded. Horizontal
and vertical viewing angles are usually defined. In the case
of projection displays the viewing angle is normally defined
to have brightness.
Widescreen
A display format with 16:9 aspect
ratio (normal displays are 4:3). Designed primarily for digital
television and home cinema.
WXGA
A 1365x768 resolution. A widescreen
variant of XGA
XGA
Extended Graphics Adapter; IBM's
graphics standard that includes VGA and extended resolutions
up to 1024x768, interlaced and non-interlaced resolution.
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