LCD Definitions
ACTIVE AREA/EFFECTIVE AREA
In the viewing area of the LCD glass, the dimensions of the
perimeter of the conductive area. LCD size is determined by the
diagonal measurement of the viewing area.
AMLCD See TFT
ANISOTROPIC ADHESIVE
Conductive spheres
contained within a thermoplastic non conducting adhesive, which
when heated and placed under pressure provide a selective
conductive path for electronic driver chips attached with the
adhesive to ITO traces on glass.
ANNUNCIATOR
A word, phrase, or symbol; an
active element.
BEZEL
A frame of plastic or metal, fitting over the LCD glass, to
protect the edges of the glass
CCFL, CCFT
Cold Cathode
Fluorescent Lamp [or Tube]
used to provide a light source which is modified by the display
and presents the graphic to the human eye.
CELL GAP
The space containing liquid crystal
fluid between the two pieces of glass.
CHIP-ON-BOARD
The LCD driver wafer is mounted on
the PCB with gold wires used to connect it to other circuits. It
is covered with epoxy.
CHIP-ON-GLASS
A new technology that mounts the
LCD driver to the contact edge of the LCD glass.
CHIP-ON-FLEX
The contact edge of the LCD glass
is mounted to a flex connector that incorporates an LCD driver.
COMMON/BACKPLANE
The superimposition of the
conductive pattern from one piece of glass to the second piece.
The duty ratio is determined by the number of backplanes.
COLD CATHODE BACKLIGHT
(CCFT)
In medium to large LCD graphic
modules, a type of fluorescent backlighting or edge lighting.
CONTACT EDGE
The area of the LCD with conductive
leads/traces where electrical connection is made by use of a
connector.
CONTRAST RATIO
The difference in luminance between
the unselected area and the selected area.
CURSOR
Dots used to indicate the location
of the next character or symbol to be entered.
DIL (Dual-In-Line)
Two parallel rows of connection
holes on a PCB. Also, the type of connector used with this array.
DIRECT/STATIC DRIVE
The method in which each conductive
lead on the contact edge connects to one segment or annunciator.
DOT/PIXEL
An active element that forms a
character or symbol when combined in a matrix.
DOT MATRIX
A group of dots/pixels forming a
character or symbol, usually five dots across and seven dots
down.
DSTN
Double Super
Twist Nematic, utilizing a fluid
composed of molecules that behave like crystals.
DUTY RATIO
1/N when N is equal to the number
of segments selected by one complete cycle.
EFFECTIVE AREA see ACTIVE AREA
ELASTOMERIC CONNECTOR
A silicone rubber strip made up of
sequentially spaced conductive and non-conductive material. An
older method of connection for LCD modules.
ELECTROPHORESIS
A dead short is created when excess
DC voltage is applied to an LCD. Conductive particles from one
piece of glass are transferred through the liquid crystal fluid
and deposited on the conductive surface of the opposite piece of
glass.
ENVELOPE See CELL GAP
FILL HOLE
The space left between the epoxy
seals on one end of the LCD glass after assembly. This space,
used to fill the glass with the liquid crystal fluid, is noted by
a mound of epoxy.
FONT
The active pattern containing the
information to be displayed in the LCD glass.
FPD, LCD, SCREEN
Used interchangeably, Flat
Panel Display, Liquid Crystal
Display, refers to the graphic monitor used
typically in Laptop Computers.
GHOSTING
A phenomenon occurring when voltage
from an energized element leaks to an adjacent OFF element and
turns the adjacent element partially ON. Typically seen on STN
and DSTN screens.
HEAT SEAL
A flexible adhesive connector
bonded by heat to the contact edge of the glass.
INTERCONNECT DOT
Consisting of silver impregnated
epoxy, it connects the pattern piece of glass to each backplane.
INVERTER, DC to AC
Converts DC to AC at a high
frequency, and powers CCFT lamps.
IPA
Isopropyl
Alcohol, typically used at 90% for pre inspection
cleaning of the Screen, and post repair prior to packaging.
ISOTROPIC STAGE
The point where the fluid heats or
cools to where it is no longer in the Twisted Nematic state.
Since the molecules can no longer twist light, all incoming light
is absorbed.
ITO
Indium Tin
Oxide refers to the typical metallization sputtered
on to the glass panel to provide electrically conductive paths.
LEADS
The conductive traces on the
contact edge of the glass.
LCD SIZE See ACTIVE AREA/EFFECTIVE AREA
LIQUID CRYSTAL FLUID
Having properties of both a solid
and a liquid, it consists of rod-shaped bipolar molecules which
are capable of twisting polarized light when in the OFF state.
MODULE
An LCD glass connected to a PCB
with drivers on board. It may also have controllers, temperature
compensation circuits, or other features.
MULTIPLEX
Using multiple backplanes in order
to reduce the number of connections between the LCD and the
drivers.
PDP
Plasma Display
Panel, earlier technology panel, using gas
excitation to produce visible display.
PITCH
The center dimension of adjacent
conductive traces, dots, or connector holes.
PIXEL see DOT
REFLECTIVE
A smooth silver piece of aluminum
foil, bonded to the rear polarizer, that reflects incoming
ambient light. Backlighting cannot be used with a reflective LCD.
SATURATION VOLTAGE
RMS. voltage required to turn fluid
to 90% on.
SEGMENT
An active element of a digit,
usually 7 segments for numeric and 14 segments for alpha/numeric
digits.
SIL (Single-In-Line)
An LCD module that has a single row
of connection holes, and an LCD glass with a single contact edge.
STATIC DRIVE see DIRECT DRIVE
STN
Super Twist
Nematic, utilizing a fluid composed of molecules
that behave like crystals.
TAB
Tape Automated
Bonding refers to the method used to package the
chip, hence the vernacular for the chip assembly.
TFT
Thin Film
Transistor, where each sub-pixel in this display
has its own active controlling transistor.
THRESHOLD VOLTAGE
RMS. voltage required to turn fluid
to 10% on.
TRANSFLECTIVE
A type of backing, bonded to the
rear polarizer, which enables light to pass through the back as
well as reflecting light from the front.
TRANSMISSIVE
An 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.
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.
Z AXIS ADHESIVE see ANISOTROPIC ADHESIVE
Z AXIS CONNECTOR see ELASTOMERIC CONNECTOR.
ZEBRA CONNECTOR see ELASTOMERIC CONNECTOR