Sanyo LCD Panel, LCD Shutter Schematic
FILE NO.
REFERENCE NO. TI5110LCD
Training Manual
Principle of LCD Display
CONTENTS
Pages
1. Construction of LCD Display ----------------------------------------------------------------------- 2 - 5
1-1 Principle of LCD Display ------------------------------------------------------------------------------- 2
1-2 Construction of LCD Display --------------------------------------------------------------------- 2 - 3
1-3 Main Component of LCD Display --------------------------------------------------------------- 4 - 5
2. Principle of Liquid Crystal --------------------------------------------------------------------------- 6 - 8
2-1 Liquid Crystal --------------------------------------------------------------------------------------------- 6
2-2 Rubbing-process------------------------------------------------------------------------------------- 6 - 7
2-3 Operation of Liquid Crystal ---------------------------------------------------------------------------- 8
3. Principle of LCD --------------------------------------------------------------------------------------- 9 - 11
3-1 Operation of Polarized Board for LCD Panel (Shutter)----------------------------------------- 9
3-2 Operation of Alignment Film------------------------------------------------------------------------- 10
3-3 Operation of LCD Panel ------------------------------------------------------------------------ 10 - 11
3-4 Transparent Electrode -------------------------------------------------------------------------------- 11
4. Type of LCD Display Construction ------------------------------------------------------------ 12 - 13
4-1 Twisted Nematic (TN) Type -------------------------------------------------------------------- 12- 13
4-2 Super TN (STN) Type---------------------------------------------------------------------------- 12- 13
4-3 Triple STN (TSTN) Type / Film STN (FSTN) Type --------------------------------------- 12- 13
5. System of LCD Display ---------------------------------------------------------------------------- 14 - 20
5-1 Dot-Matrix System ------------------------------------------------------------------------------------- 14
5-2 Colorization ---------------------------------------------------------------------------------------------- 15
5-3 Drive System -------------------------------------------------------------------------------------------- 16
5-4 Passive Matrix System-------------------------------------------------------------------------- 16 - 17
5-5 Active Matrix System---------------------------------------------------------------------------- 18 - 19
5-6 Drive of Active Matrix System----------------------------------------------------------------- 19 - 20
6. Improvement Technology of LCD Display -------------------------------------------------- 21 - 27
6-1 Subject of LCD Display ------------------------------------------------------------------------------- 21
6-1-1 Angle of View----------------------------------------------------------------------------------------- 21
6-1-2 Response Characteristic--------------------------------------------------------------------------- 21
6-2 Angle of View-------------------------------------------------------------------------------------------- 22
6-3 Multi-Domain System --------------------------------------------------------------------------------- 23
6-4 MVA (Multi-domain Vertical Alignment) System ----------------------------------------------- 24
6-5 IPS (In-Plain Switching) System ------------------------------------------------------------------- 25
6-6 Optically Compensated Film ------------------------------------------------------------------------ 26
6-7 OCB (Optically Compensated Birefringence) System ---------------------------------------- 26
6-8 Improvement of Response Speed ----------------------------------------------------------------- 27
6-8-1 Inpulse System--------------------------------------------------------------------------------------- 27
6-8-2 FFD (Feed Forward Driving) System----------------------------------------------------------- 27
7. Appendix ----------------------------------------------------------------------------------------------- 28 - 31
7-1 Backlight-------------------------------------------------------------------------------------------------- 28
7-2 LVDS Circuit--------------------------------------------------------------------------------------------- 29
7-3 Block Diagram Example------------------------------------------------------------------------ 30 - 31
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Training Manual Principle of LCD
■ Construction of LCD Display
1. Construction of LCD Display
1-1 Principle of LCD Display
The LCD (Liquid Crystal Device) Display is used to display the electric signal, converted from picture
data similar to a CRT display. The transistor (TFT) switched by the electric signal changes the transmis-
sion to light in small picture elements (pixels) of the LCD. The LCD display makes the picture by grouping
these elements of each RGB color.
1-2 Construction of LCD Display
LCD Display
Liquid Crystal is packed between the board modules (TFT and Common) and the LCD panel (or LCD
shutter) is constructed. A back light is attached to the LCD panel for LCD Display.
Board Module (Common Electrode)
The Common Electrode consists of a polarized board, a color filter, and a transparent electrode on a
glass plate. An alignment film is formed on the transparent electrode.
Board Module (TFT Electrode)
The TFT Electrode consists of a polarized board and a transparent electrode (pixel electrode and drive
transistor) on a glass plate. An alignment film is formed on the transparent electrode.
Backlight
A fluorescent light is used for the Backlight.
✐ TFT:
Thin Film Transistor
✐ LCD Panel and LCD Shutter: They are the same things, but in the explanation LCD panel is used
for structure and LCD shutter is used for function.
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Training Manual Principle of LCD
Construction of LCD Display
Note: Alignment film is not
shown in this figure.
Fig. 1 Construction of LCD Display
(Transparent Type TFT LCD)
Backlight
Board
Module
(TFT side)
Polarized
Board
Glass
Plate
Pixel
(Picture Element)
Transparent
TFT
Electrode
(Pixel, TFT)
Transparent
Electrode
(Common)
Color Filter
Glass
Plate
Polarized
Board
LCD Layer
Board Module
(Common side)
The light of each picture element is transmitted
by switching the drive transistor (TFT) on and off.
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Training Manual Principle of LCD
Construction of LCD Display
1-3 Main component of LCD Display
LCD Shutter
Supplying voltage to the transparent electrodes between the pixel and common sides changes the
arrangement of liquid crystal. By assembling two polarized boards, the transfer of light from the backlight
can be controlled by the transparent ratio of the LCD Shutter.
Liquid Crystal
Liquid Crystal is a material whose state is between a solid and a liquid. It has both characteristics of
solids and liquids, and generally it is a white turbid liquid. Its molecules are normally arranged compara-
tively opaque and change to transparent with the application of voltage or heat.
Transparent Electrode (Film)
An LCD shutter is operated by supplying voltage derived from the video signal. Transparent film is used
for its electrode.
Alignment Film
This is a film for arranging liquid crystal molecules and is made of Polymid resin.
Polarized Board
The light with a specified direction passes through a polarized board.
Drive Transistor
The thin film transistor (TFT) is used to drive the LCD shutter of each pixel.
Color Filter
It is a filter with three colors (R, G, B) arranged for each pixel.
Backlight
Liquid crystal does not emit light. A light source is needed for display. The light source placed on the
reverse side of the LCD panel is called “Backlight.”
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Training Manual Principle of LCD
Construction of LCD Display
Fig. 2 Construction of LCD Display
(Cross Section)
Fig. 3 Assembly of LCD Display
Backlight
LCD
Shutter
Module
(Back)
LCD Layer
Module
(Front)
Polarized
Board
Glass
Plate
Transparent Electrode
(Pixel, TFT)
Alignment Film
Liquid Crystal
Alignment Film
Transparent Electrode
(Common)
Color Filter
Glass Plate
Polarized
Board
LCD
Display
LCD
Module
Backlight
LCD Panel
(LCD Shutter)
TFT Display
Drive Circuit
(with IC)
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Training Manual Principle of LCD
2. Principle of Liquid Crystal
2-1 Liquid Crystal
What is Liquid Crystal?
Liquid Crystal is a material whose state is between a solid and liquid. It has characteristics of both solids
and liquids, and generally is a white turbid liquid. Its molecules are normally arranged comparatively
opaque and change to transparent with the application of voltage or heat.
Almost all the materials consist of an organic compound taking the form of a slender stick or a flat plate.
There are three types of liquid crystal as shown in Fig. 4, and they depend on the construction and
arrangement of molecules.
Generally Nematic liquid crystal is used for the display apparatus.
(a) Smectic
Molecules are in layers and arranged parallel to each other. The center of gravity is arranged at random
in the layer.
(b) Nematic
Molecules are not in layers. They are arranged parallel. The center of gravity is able to move freely to the
major axis.
(c) Cholesteric
Molecules are in layers and arranged parallel. The arranging direction of the major axis for the neighbor-
ing layers is shifted gradually.
In order to use liquid crystal for display, it is necessary to regularly arrange the molecules of Nematic
(Rubbing-process).
2-2 Rubbing-process
After chemicals for arranging are put on the glass plate, they are hardened, and then the surface on the
plate is rubbed with a cloth to fix the direction of the gaps that are made. The arranging direction of mole-
cules is settled in the gaps.
This process is used to change the characteristics so the molecules that touch the rubbed surface are
arranged to the major axis of the rubbed direction.
This thin film on the glass plate is called “Alignment film.”
■ Principle of Liquid Crystal
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Training Manual Principle of LCD
Principle of Liquid Crystal
Fig. 4 Liquid Crystal
(a) Smectic
(c) Cholesteric
(b) Nematic
Fig. 5 Rubbing-Process
Natural Condition
Liquid Crystal Molecule
Arranging
Rubbing
Direction
Alignment Film
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Training Manual Principle of LCD
Principle of Liquid Crystal
2-3 Operation of Liquid Crystal
The chemistry substance required for liquid crystal material is one that reacts so that the arrangement
direction is changed according to an applied electric field.
In the LCD display, a liquid crystal is placed between two electrodes. When the voltage is supplied
between them, an electric field is generated in the liquid crystal, and liquid crystal molecules are moved
and arranged. The Backlight applied to the liquid crystal is either passed or blocked according to the
arrangement of the molecules.
If an electric field from an external source is applied to liquid crystal, electric dipoles will be generated
that will react to the intensity and direction of the electric field. Through the operation of these electric
dipoles and the electric field, the power changing direction of liquid crystal molecules is generated.
Therefore, according to an external electric field, liquid crystal molecules move and change direction
from horizontal to vertical.
Fig. 6 Operation of Liquid Crystal
Electric
Field
Transparent
Electrode
Liquid Crystal
Electric
Field
Liquid Crystal
Molecule
Electric
Dipole
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Training Manual Principle of LCD
3. Principle of LCD
3-1 Operation of Polarized Board for LCD Panel (Shutter)
Light is an electromagnetic wave that is oscillating at right angles to the direction of advance. In fact, the
oscillating directions of all light is mixed. A polarized board can let only the light in the specific direction
pass from the light with which these various oscillating directions were mixed. Therefore, only the light of
the same direction as the polarization direction of a polarized board can be taken out by letting the light
pass through this polarized board. That is, if the oscillating direction of light and the direction of a polarized board are in agreement, the light will pass through a polarized board. Moreover, if the direction of a
polarized board differs from the oscillating direction of light, the light cannot pass through a polarized
board. When the oscillating direction of a polarized board and light are shifted 90º(right-angled), the light
is blocked completely. The light passes and looks bright if the two boards are in the same direction when
looking at two polarized boards in piles, however, if shifted at right-angles, the light is blocked and looks
dark.
■ Principle of LCD
Fig. 7 Operation of
Polarized Board
Fig. 8 Operation of
Polarized Board
Oscillating direction of light
Oscillating direction of light
The oscillating direction
of light and the direction
of a polarized board are
in agreement.
The direction of a
polarized board differs
from the oscillating
direction of light
Passage Interception
The two boards are
the same directions.
The two boards are
shifted right-angled.
Polarized
Board
Light
Light
White
Black
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Training Manual Principle of LCD
3-2 Operation of Alignment Film
Liquid crystal is inserted into alignment films of an upper and lower plate that have the direction of
grooves shifted by 90º on the LCD display. The liquid crystal molecules of upper alignment plate are
arranged along with the upper alignment film. The liquid crystal molecules of lower alignment plate are
arranged along with the lower alignment film. The liquid crystal layer between these alignment films is
twisted little by little and is arranged so that a spiral is formed. Light entering through the first alignment
plate will have its oscillating direction twisted 90º by the liquid crystal layer between the alignment films.
Now the direction of oscillation is aligned with the second alignment plate and the light will pass through.
Principle of Liquid Crystal
Fig. 9
Operation of
Alignment Film
By the upper-and-lower
alignment films, spirally, a
liquid crystal molecules are
twisted 90º and arranged.
3-3 Operation of LCD Panel
In the LCD panel, a liquid crystal is inserted and enclosed between two glass plates. The polarized
board, transparent electrode, and the alignment film are formed on these glass plates. The light can be
passed or blocked by supplying voltage or not to this LCD panel.
In the condition (Switch-Off) that the voltage is not supplied, the liquid crystal molecules are twisted 90º
sideways and arranged spirally. The oscillating direction of the light that passed the upper polarized
board is changed by the twisted liquid crystal molecule arrangement. Therefore, the direction of a polar-
ized board and the oscillating direction of the light which is shifted 90º and arranged become the same,
and this light can now pass through a polarized board. This is the liquid crystal shutter-on condition and
an LCD panel (LCD shutter) passes the light.
Alignment
Plate
Alignment
Film
Direction
of Groove
Liquid
Crystal
Molecule
Alignment
Film
Direction
of Groove
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