Sanyo LCD Training Manual

8/12/2019 Sanyo LCD Training Manual

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FILE NO.

REFERENCE NO. TI5110LCD

Training Manual

Principle of LCD Display

CONTENTSPages

1. Construction of LCD Display ----------------------------------------------------------------------- 2 - 51-1 Principle of LCD Display ------------------------------------------------------------------------------- 21-2 Construction of LCD Display --------------------------------------------------------------------- 2 - 31-3 Main Component of LCD Display --------------------------------------------------------------- 4 - 5

2. Principle of Liquid Crystal --------------------------------------------------------------------------- 6 - 82-1 Liquid Crystal --------------------------------------------------------------------------------------------- 62-2 Rubbing-process------------------------------------------------------------------------------------- 6 - 72-3 Operation of Liquid Crystal ---------------------------------------------------------------------------- 8

3. Principle of LCD --------------------------------------------------------------------------------------- 9 - 113-1 Operation of Polarized Board for LCD Panel (Shutter)----------------------------------------- 93-2 Operation of Alignment Film------------------------------------------------------------------------- 103-3 Operation of LCD Panel ------------------------------------------------------------------------ 10 - 113-4 Transparent Electrode -------------------------------------------------------------------------------- 11

4. Type of LCD Display Construction ------------------------------------------------------------ 12 - 134-1 Twisted Nematic (TN) Type -------------------------------------------------------------------- 12- 134-2 Super TN (STN) Type---------------------------------------------------------------------------- 12- 134-3 Triple STN (TSTN) Type / Film STN (FSTN) Type --------------------------------------- 12- 13

5. System of LCD Display ---------------------------------------------------------------------------- 14 - 205-1 Dot-Matrix System ------------------------------------------------------------------------------------- 145-2 Colorization ---------------------------------------------------------------------------------------------- 155-3 Drive System -------------------------------------------------------------------------------------------- 165-4 Passive Matrix System-------------------------------------------------------------------------- 16 - 175-5 Active Matrix System---------------------------------------------------------------------------- 18 - 195-6 Drive of Active Matrix System----------------------------------------------------------------- 19 - 20

6. Improvement Technology of LCD Display -------------------------------------------------- 21 - 276-1 Subject of LCD Display ------------------------------------------------------------------------------- 216-1-1 Angle of View----------------------------------------------------------------------------------------- 216-1-2 Response Characteristic--------------------------------------------------------------------------- 21

6-2 Angle of View-------------------------------------------------------------------------------------------- 226-3 Multi-Domain System --------------------------------------------------------------------------------- 236-4 MVA (Multi-domain Vertical Alignment) System ----------------------------------------------- 246-5 IPS (In-Plain Switching) System ------------------------------------------------------------------- 256-6 Optically Compensated Film ------------------------------------------------------------------------ 266-7 OCB (Optically Compensated Birefringence) System ---------------------------------------- 266-8 Improvement of Response Speed ----------------------------------------------------------------- 276-8-1 Inpulse System--------------------------------------------------------------------------------------- 276-8-2 FFD (Feed Forward Driving) System----------------------------------------------------------- 27

7. Appendix ----------------------------------------------------------------------------------------------- 28 - 317-1 Backlight-------------------------------------------------------------------------------------------------- 287-2 LVDS Circuit--------------------------------------------------------------------------------------------- 297-3 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 aglass 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 LCConstruction of LCD Display

BoardModule

(TFT side)

Board Module(Common side)

The light of each picture element is transmittedby switching the drive transistor (TFT) on and off.

LCD Layer

Backlight

PolarizedBoard

PolarizedBoard

Pixel(Picture Element)

TFTTransparentElectrode

(Pixel, TFT)

Color Filter

TransparentElectrode(Common)

GlassPlate

GlassPlate

Note: Alignment f i lm is not

shown in this figure.

Fig. 1 Construction of LCD Display

(Transparent Type TFT LCD)


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Training Manual Principle of LCDConstruction 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 LCConstruction of LCD Display

Backlight

PolarizedBoard

PolarizedBoard

GlassPlate

Glass Plate

Alignment Film

Alignment Film

Liquid Crystal

Transparent Electrode(Pixel, TFT)

Transparent Electrode(Common)

Color Filter

Module(Back)

Module(Front)

LCD LayerLCDShutter

TFT DisplayDrive Circuit(with IC)

LCDDisplay

Backlight

LCDModule

LCD Panel(LCD Shutter)

Fig. 2 Construction of LCD Displa

(Cross Section)

Fig. 3 Assembly of LCD Display


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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


7/32-7-

Training Manual Principle of LCPrinciple of Liquid Crystal

Alignment Film

Arranging

RubbingDirection

Natural Condition

Liquid Crystal Molecule

Fig. 4 Liquid Crystal

(a) Smectic

(c) Cholesteric

(b) Nematic

Fig. 5 Rubbing-Process


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Training Manual Principle of LCDPrinciple 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.

Electric

Dipole

Liquid Crystal

Molecule

Liquid Crystal

Electric

Field

Electric

Field

TransparentElectrode

Fig. 6 Operation of Liquid Crystal


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Training Manual Principle of LC

3. Principle of LCD3-1 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, th

oscillating directions of all light is mixed. A polarized board can let only the light in the specific directio

pass from the light with which these various oscillating directions were mixed. Therefore, only the light o

the same direction as the polarization direction of a polarized board can be taken out by letting the lig

pass through this polarized board. That is, if the oscillating direction of light and the direction of a pola

ized board are in agreement, the light will pass through a polarized board. Moreover, if the direction of

polarized board differs from the oscillating direction of light, the light cannot pass through a polarize

board. When the oscillating direction of a polarized board and light are shifted 90(right-angled), the lig

is blocked completely. The light passes and looks bright if the two boards are in the same direction whe

looking at two polarized boards in piles, however, if shifted at right-angles, the light is blocked and look

dark.

Principle of LCD

PolarizedBoard

White

Light Light

Black

Fig. 7 Operation ofPolarized Board

Fig. 8 Operation ofPolarized 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 apolarized board differs

from the oscil lating

direction of light

Passage Interception

The two boards are

the same directions.

The two boards are

shifted right-angled.


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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 90 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 90 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

AlignmentFilm

Alignment

Film

AlignmentPlate

Directionof Groove

Directionof Groove

LiquidCrystal

Molecule

Fig. 9 Operation ofAlignment Film

By the upper-and-lower

alignment films, spirally, a

liquid crystal molecules are

twisted 90 and arranged.

3-3 Operation of LCD Panel

In the LCD panel, a liquid crystal is inserted and enclosed between two glass plates. The polarizedboard, 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 90

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 90 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.


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Training Manual Principle of LCPrinciple of Liquid Crystal

LightLight

PolarizedBoard Polarized

Board

PolarizedBoard

TransparentElectrode(Lower)

TransparentElectrode(Upper)

AlignmentFilm

LiquidCrystal

AlignmentFilm

PolarizedBoard


(Lower)


(Upper)

AlignmentFilm

LiquidCrystal

Alignment

Film

Fig. 10 Operation ofLCD PanelPassage Interception

3-4 Transparent ElectrodeIn order to generate an electric field in liquid crystal, voltage is supplied to the upper-and-lower elec

trodes. If metal is used for these electrodes, the light is interrupted by this metal and cannot pass into th

liquid crystal. Therefore, a transparent electrode that passes light is used for the electrode of the LC

shutter.

On the contrary, in the condition (Switch-On) that voltage is supplied, the liquid crystal molecules ar

arranged in a line at right angles to a glass plate. Since vertical liquid crystal molecules do not affect th

oscillating direction of light, the light that passed the upper polarized board passes as it is without chan

ing the oscillating direction. Since the oscillating direction of this light differs from direction of the low

polarized board which is shifted 90 and arranged, the light collides with this polarized board and cann

pass. This is the liquid crystal shutter-off condition and the LCD panel (LCD shutter) blocks the light.

This is the basic structure (OnOff of the light by the LCD shutter) of an LCD panel. It is a sandwic

structure of the upper and lower sides of transparent electrodes, alignment films, and polarized board

with an enclosed liquid crystal material between them.

The LCD panel shown in Fig. 10 is a type of panel that changes the light into a passage condition whe

voltage is not supplied between the upper-and-lower polarized boards that are arranged at 90. This typ

of panel has the advantage that black contrast is improved, and it usually works well. This mode is calle

Normally White Mode.

An LCD panel that passes light when voltage is not supplied is referred to as Normally Black Mode. I

practice, with this type (when the upper-and-lower polarized boards are arranged in the same direction

displaying perfect black becomes difficult due to the leakage of light caused by variations in the arrangment of the liquid crystal molecules.


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Training Manual Principle of LCD Type of LCD Display Construction

4 Type of LCD Display Construction

4-1 Twisted Nematic (TN) Type

A Nematic type of LCD Display where the liquid crystal molecules are twisted 90 between upper and

lower boards is called a Twisted Nematic type (TN type) liquid crystal.

Most LCD displays are of this type and feature high contrast (ratio) under low voltage and power.

4-2 Super TN (STN) Type

Super TN type (STN type) LCD Displays are used for LCD televisions, personal computer monitors, cel-

lular phones, etc. A liquid crystal material developed to improve visual characteristics, such as contrast

ratio is used.

In this STN type liquid crystal molecules are twisted 180 to 270 and arranged between upper and lower

electrodes. By supplying voltage to this liquid crystal, the transparent ratio of light changes more steeply.

Therefore, with the STN type as compared to the TN type, contrast and rise characteristic of the voltage

(response of switch On and Off) are improved, and a clearer picture on larger screens becomes possible.

4-3 Triple STN (TSTN) Type / Film STN (FSTN) Type

A fault of the STN type is that the display colors during On and Off of the LCD shutter become yellowish

green and navy blue. (In TN type, they are white and black.) This is because light of a specific wave-

length is reflected and scattered by the thickness of the LCD panel. Therefore, even if a color filter of

RGB is attached to an STN type liquid crystal, bluish green is mixed with the colors from black, gray to

white, and a natural color picture cannot be displayed. The triple STN type (TSTN type) and the film STN

type (FSTN type) have been developed as an advanced type of STN.

In the TSTN type, optically compensated films (high polymer films) which sandwich the upper and lower

LCD panels are used. They compensate for the twist of the light crystal cell, and the display colors of yel-

lowish green and navy blue are changed to the correct white and black. The FSTN type uses a single

optically compensated film


13/32-13-

Training Manual Principle of LCType of LCD Display Construction

Module

LCD Layer

Module

Module

LCD Layer

Module

Module

LCD Layer

OpticallyCompensated

Film

Module

OpticallyCompensated

Film

Fig. 11 Type of LCD Display Construction

Twist of molecule

(90)

Twist of molecule

(180 - 270)

TSTN Type

STN Type

TN Type


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5 System of LCD Display

5-1 Dot-Matrix System

LCD displays have two drive systems, Segment and Dot-Matrix. The Dot-Matrix system is used for LCD

television displays.

The picture elements (pixels) of the display unit are arranged horizontally (X line) and vertically (Y row)

by this Dot-Matrix system, and various characteristics and figures can be displayed.

Fig. 12 shows a matrix of X x Y = 10 (pixels) with the character Y displayed. In this Dot-Matrix system,

by making the size of a pixel smaller and increasing the whole number of pixels, the big screen with fine

character or picture becomes possible.

With the present liquid crystal manufacture technology, the number of pixels per inch has reached

200ppi*, and very high definition screen display is possible. Moreover, the number of pixels of an LCD

display panel corresponding to bigger screen sizes can be specified and manufactured. For example, the

number of pixels of the SXGA* panel is about 1,300,000 (1,280 x 1,024 = 1,310,720 pixels).

ppi: pixel per inch

SXGA: Super eXtended Graphics Array

System of LCD Display

Y

X

R G B

Fig. 12 Dot-Matrix System

In colorization of LCD panel,

one pixel consists of 3 RGB

dots (sub-pixels).

A character or a figure is

displayed by making the

pixel of each X and Y inter-

section turn on (or off).


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5-2 Colorization

Since an LCD shutter only passes or blocks light, in itself it cannot display a color picture. The color pic

ture is made by mixing the three colors of RGB (three primary colors of light) respectively, like the CR

color television. The color LCD panel has a color filter of RGB attached to the monochrome panel. Se

Fig. 13. In this color LCD panel, by controlling the voltages and the waveforms that are supplied at eac

RGB pixel, the transparent ratio is controlled and hue and brightness are adjusted. Therefore, smalle

pixels and more numbers of pixels are required for the color LCD Display. For example, although th

SXGA panel described before has about 1,300,000 pixels, in colorization, there are about 4 million dot

(sub-pixels).


Fig. 13 Colorization of LCD Display

R G

B

LCD ShutterColor Filter

Backlight

White

Color

LCD Shutter

Backlight

White

Mono

chrom

e

Color Panel Monochrome Panel


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5-3 Drive System

The drive systems for LCD display are divided into the following classifications:

The Static Drive System, which is seldom used;

The Passive Matrix System, which is used for still pictures, such as calculators and notebook PCs;

The Active Matrix System, which is suitable for high definition and the high-speed response needed for

big screen LCD television.


Drive System Static Drive System

Dynamic Drive System Passive Matrix System

Active Matrix SystemClassification of LCD Drive System

5-4 Passive Matrix SystemIn the structure of a passive matrix system, Y electrodes of the vertical direction (Y-direction) are formed

in upper glass plate, and X electrodes of the horizontal direction (X direction) are formed in lower glass

plate as a matrix. The liquid crystal molecules are sandwiched between these electrodes. By supplying

voltage between the Y electrode and the X electrode in sequence, at a certain time, an electric field is

generated in the liquid crystal where the selected Y electrode and X electrode cross. Therefore, the liquid

crystal molecules of this pixel address (X, Y electrode intersection) change arrangement and an LCD

shutter is turned On or Off.

GlassPlate

Y Electrode

X Electrode

Y0 Y1 Y2 Y3 Y4

GlassPlate

LiquidCrystalLayer

X0

X1

X2X3

X4

Fig. 14 Passive Matrix System

These electrodes are

transparent electrodes.


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Training Manual Principle of LCSystem of LCD Display

Y1

Y0 Y1 Y2

LiquidCrystal

X2

X0

X1

X2

X3

Fig. 15 Passive Matrix System

LCD shutter is turned on

or turned off in thisaddress (X2, Y1).

In the dynamic drive system, since the electric signal (voltage) is supplied to the Y electrode and the

electrode in sequence, the number of pixels which makes all pixels (the total number of pixels are X

Y) turn on or off becomes X+Y. Therefore, compared with the static drive system that has an indepe

dent electrode for each pixel, the number of electrodes of the dynamic drive system is very few.

However, with this dynamic drive system, since the electrode itself is the wiring, it has resistance th

cannot be disregarded in the big screens. This resistance causes the speed of the shutter to becom

slower. Therefore, when displaying moving pictures etc., an afterimage is generated.

This passive matrix system is not suitable for LCD televisions with big screens that require moving pic

tures and high resolution.

The active matrix system was developed in order to overcome these faults.


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5-5 Active Matrix SystemIn the active matrix system, a switch element is attached for every pixel at the intersection of the X and Y-

electrodes of a passive matrix system. Each pixel is now controlled by the switch element (active ele-

ment). Since the switch for each pixel is turned On and Off independently, the response speed is

increased. Thin Film Transistor (TFT) is used for the switch element and is attached on the glass board.

The LCD display using this TFT is called TFT LCD display.The upper electrode for the whole pattern is formed on the upper glass plate and is called the Common

Electrode. A pixel electrode (pixel pattern), TFT (switch element) which drives a pixel electrode, and X

electrode for gate input and Y electrode for source input of TFT are formed on the lower glass plate. In

this structure, the electric field is generated in the area between the pixel electrode and the common

electrode, and the LCD shutter for 1 pixel is operated.

When an electric signal (voltage) is supplied to the Y and X electrode of TFT, TFT is turned On, and the

liquid crystal molecules are operated as a light switch. Refer to Fig. 17 (Address X1 and Y0).


Glass Plate(Upper)

Y Electrode

X Electrode

Pixel Electrode(Pixel Pattern)

Glass Plate(Lower)

LiquidCrystalLayer

COMMONElectrode

TFT(Switch Element)

Y Electrode

Equivalent Circuit(TFT)

Y0

Y0

Y1

X1

X1

Y0

X1

X2

X Electrode

Pixel Electrode

Pixel

Electrode

Liquid

Crystal

LiquidCrystal

COMMONElectrode

COMMON

COMMONElectrode

Drain

Gate

SourceTFT TFT

Equivalent Circuit(Switch)

COMMON

Drain

Gate

Source

Switch(On / Off)

Fig. 16 Structure of ActiveMatrix System

Fig. 17 Equivalent Circuit ofActive Matrix System

By TFT, the shutter of a pixel at the

address (X1, Y0) is turned On or Off.


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Training Manual Principle of LCSystem of LCD Display

Y0 Y1 Y2 Y3

X0

X1

X2

X3

Liquid Crystal

COMMON Electrode

TFT (Switch)

Fig. 18 Structure of TFT Matrix

The LCD shutter is operated by

TFT at the address (X1, Y0).

The amplification operation of a transistor is used for the TFT switch in the active matrix system. In th

system, switching speed is unified over the whole display, increasing drive response speed as compare

with the passive matrix system. Therefore, TFT LCD display (active matrix system) is adopted for th

highly efficient display, which can provide the response speed required for big screens or quickly movin

pictures. However, further response speed is needed for high definition LCD television. This will b

described later.

5-6 Drive of Active Matrix SystemThe TFT LCD display consists of a matrix of n lines of X direction (X0 - Xn-1) and of n rows of Y directio(Y0 - Yn-1). The line of X direction is called the gate line and the line (row) of Y direction is called th

data line.

First, the scan is started from the pixel address

(X0, Y0), and when the address (X0, Yn-1) is

selected the scan of X0 line is completed. Next, all

the pixels from X1 line to Xn-1 line are scanned in

sequence, and the final address is (Xn-1, Yn-1).

The operation of selected pixel address (X1, Y2)

is explained below.

First, (signal) voltage is supplied to X1 line (gateof TFT), next voltage is supplied to Y2 row (source

of TFT), and the address of the intersection of X1

line and Y2 row is selected and its TFT is turned

On or Off. However, just switching the TFT on and

off will not change the brightness of the screen.

The brightness of a screen is changed by control-

ling the voltage of a data line (Y row). Fig. 19

shows the voltage characteristic of the matrix sys-

tem.

Time

Active Matrix System

Voltagetoliqu

idcrystal

Passive Matrix System

Fig. 19 Voltage Characteristic of Matrix System

Since the time for the drive voltage to reach itsrequired value is shorter in the active matrix system,the response time of the display becomes quicker.


20/32-20-


In Fig. 20, the voltage of the data line (Y2) is supplied in the positive direction to a common electrode

(DC drive). In practice a uniform AC voltage is supplied to the common electrode (AC drive) to prolong

the life of the liquid crystal.

Y0

Data Line Drive Circuit (Y row)

GateL

ineDriveCircuit(X

line)

Y1 Y2 Y3

Yn-1

X0

X1

X2

X3

Xn-1

COMMON

COMMON

COMMON

Brightnessof Screen

Power

Circuit

X Direction

VariableVoltage

TFT: On (X1, Y2)

TFT: On

TFT: Off

Video DataProcessor

Timming Controller(Scan Converter)Y Direction

X1

Y2

Y2

Y2

Y2

Y2

LiquidCrystal

PixelElectrode

Glass Plate(Common)

Glass Plate(TFT)

TFT

Fig. 20 LCD Drive Circuit (Normally White Type)

In practice, driven by AC signal

to COMMON. (AC Drive)



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6 Improvement Technology of LCD Display

6-1 Subject of LCD Display

6-1-1 Angle of View

Angle of view means the normal visible range (angle) of a screen.

In an LCD display, the angle of view is narrow compared with a CRT or PDP (Plasma Display Panel). Th

viewing angle of the typical TN type LCD display is about 100. However with the new improved technol

gy that has been developed the angle of view for LCD display has increased to 160 or 170. Th

improved system will be described later. (The angle of view for a CRT or PDP is 180.)

Improvement Technology of LCD Display

6-1-2 Response Characteristic

The response characteristic of the LCD display is the speed at which the display is refreshed by the inp

signal (video data signal).

If this response characteristic is slow, an afterimage will appear on the screen. Therefore, in large scree

LCD television, improving this response characteristic becomes very important.

Angle of View

Angle of View

Vertical

Horizontal

Fig. 21 Angle of View


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6-2 Angle of View (TN Type)

The principle of optical penetration and the interception of the LCD shutter by the arranged direction of

cylindrical liquid crystal molecules controls the direction of light. Therefore, brightness, hue, and contrast

depend on the direction of view of the LCD display. The range (angle) where these look normal is called

the angle of view. The fault of the TN LCD display is that this angle of view is narrow.

Fig. 22 shows that brightness changes depending on the angle the screen with a gray picture is viewed.

In this figure, the liquid crystal molecule leans diagonally. Therefore, the amount of optical penetration will

change depending on the angle when watching the screen from the front or the side.

PolarizedBoard

PolarizedBoard

GlassPlate

Alignment Film

Alignment Film


GlassPlate



Fig. 22 Angle of View (TN type)


The brightness becomes

different depending on the

angle of view.


23/32-23-


6-3 Multi-Domain System

The arrangement of the TN LCD display is one directional. In this Multi-Domain System, one pixel is

divided into two or more different arranged domains.

Fig. 23 shows the example of Multi-Domain System with two domains. The quantity of the light per pixe

from various angles is equalized by this system. Moreover, the angle of view becomes even wider by

increasing the number of divisions. However, manufacturing is difficult in the rubbing process*.

Refer to 2-2 Rubbing-process.


PolarizedBoard

PolarizedBoard

GlassPlate

Alignment Film

Alignment Film(Right)


GlassPlate


Alignment Film(Left)


Fig. 23 Multi-Domain System

The brightness of a scree

is equalized as macro view.


24/32-24-

Training Manual Principle of LCDImprovement Technology of LCD Display

6-4 MVA (Multi-domain Vertical Alignment) System

In the MVA system, the (alignment) film is arranged so that the liquid crystal molecules are stood vertical-

ly. The MVA system combines vertical alignment with the Multi-domain system. By vertically aligning the

liquid crystal molecules, the influence of optical interception is lost, and the angle of view and contrast

are improved.

A type of material is used that causes the liquid crystal molecules to become vertical to the glass plate

without supplying voltage. (Nega-Nematic liquid crystal*)

In the MVA system, attaching the boss by resin and making the liquid crystal molecules stand diagonally

on the transparent electrode make multiple alignment domains. Therefore, since the rubbing process can

be skipped at the alignment film production, manufacturing becomes easier compared with the multi-

domain system.

Generally, a Posi-Nematic system is used that aligns the liquid crystal molecules by supplying voltage.

PolarizedBoard

PolarizedBoard

GlassPlate

Alignment Film

(Right)

Liquid Crystal Molecule(Nega-Nematic)

GlassPlate


Alignment Film

(Left)


Boss

Fig. 24 MVA (Multi-domain Vertical Alignment) System


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Training Manual Principle of LCImprovement Technology of LCD Display

6-5 IPS (In-Plain Switching) SystemThe structure of an IPS system is shown in Fig. 25. The pixel and common electrodes are mounted

the transparent film (drive transistor) side and the electric field is generated horizontally to the glas

plate. With this electric field, the alignment direction of liquid crystal molecules is rotated 90 in parallel

the glass plate.

In the IPS system, liquid crystal molecules rotate all at once in the horizontal direction. Since these liqu

crystal molecules do not lean like the TN type, there is little change in the picture characteristics (con

trast, brightness, hue, etc.) and the angle of view becomes wider. However, there are a few problem

The quantity of transparent light is reduced, slower response speed, and a white picture becomes a litt

bluish or yellowish depending on the viewing direction. The S-IPS (Super-IPS) type was developed t

improve upon these problems. In the S-IPS type, the structure of the electrode for driving the liquid cry

tal molecules becomes a zigzag form, which reduces the change of color, increases the viewing angle t

about 160 and has high definition equivalent to a CRT.

Polarized

Board

PolarizedBoard

PolarizedBoard

Glass Plate(Without Transparent Electrode)

Alignment Film

Alignment Film

Liquid Crystal Molecule(Vertical)

Liquid CrystalMolecule

(Vertical)

ElectricField

Dark (Switch Off) Bright (Switch On)

Glass Plate

Transparent Electrode(Pixel)


Alignment Film

Fig. 25 IPS (In-Plain Switching) System

Basic Structure of IPS System

Normally Black Mode


26/32-26-

Training Manual Principle of LCDImprovement Technology of LCD Display

6-6 Optically Compensated FilmBy using the optically compensated film, the phase shift of the STN type of LCD display is corrected, and

the angle of view and contrast are improved.

(Refer to 4-3 Triple STN Type.)

Three methods for attaching the optically compensated film are shown in Fig. 26.

Polarized Board

PolarizedBoard

CompensatedFilm

Liquid Crystal

Polarized Board

PolarizedBoard

Compensated Film 1

Liquid Crystal

Compensated Film 2

Polarized Board

PolarizedBoard

CompensatedFilm 1

Liquid Crystal

CompensatedFilm 2

Fig. 26 Optically Compensated Film

1 sheet / 1 side 2 sheets / 1 side 2 sheets / 2 sides

6-7 OCB (Optically Compensated Birefringence) SystemThe OCB system combines the bend-alignment system where the liquid crystal molecules are bent and

aligned between the upper and lower boards and optically compensation film. This system has the fea-

tures of increased angle of view and quicker response speeds. However, bend-alignment is difficult to

make uniform and stable.

Optically CompensatedFilm

PolarizedBoard

Polarized Board

GlassPlate

Alignment Film

Alignment Film


GlassPlate



Fig. 27 OCB System


27/32-27-


6-8 Improvement of Response Speed

6-8-1 Inpulse System

In order to reduce afterimage and dim outline, there is the system that has the backlight blinked for eve

writing of one picture or an all black picture in inserted in the fixed cycle. It is called the Inpulse System

For example, with the system called Super Inpulse System, the black data is written in every 1/60 sec

ond, and the afterimage and the ghosts are reduced.


With the usual LCD panel, since th

picture is displayed continuously

the front picture becomes dim a

the afterimage.

In the inpulse system, by insertin

black data between the pictur

data, the afterimage is reduced an

the high-speed response i

improved.

Picture Data

Black Data

Fig. 28 Inpulse System

6-8-2 FFD (Feed Forward Driving) System

The response speed of LCD brightness can be improved by adding over-shoot characteristic to the da

line voltage. Fig. 29 shows the actual overdrive circuit used in a digital drive system.

Time

Over-Shoot

Voltage

Time

ResponseTime

Brightness

Time

Voltage

Time

Voltage

Time

Response Time(By Overdrive Circuit)

Brightness

Time

Voltage

Fig. 29 Overdrive Circuit

Waveform (Normal) Waveform with Over-Shoot

Drive Circuit (Normal) Overdrive Circuit


28/32-28-


7 Appendix

7-1 Backlight

An LCD panel does not emit light itself. For the display, a light source is required, and normally fluores-

cent lights are used for the backlight of the LCD television.

The backlight consists of fluorescent lights, a reflective plate, and a diffusion sheet (or board). Fig. 30

shows the structure and photograph of 30V and 15V LCD televisions backlights.

Fig. 30 Backlight

30V Type

15V Type

Diffusion Sheet (Board)

Reflective PlateFluorescent Lights(30V: 16pcs)

LCD Panel

Diffusion Sheet

Reflective PlateFluorescent Lights(15V: 2pcs, 20V:3pcs)

LCD Panel

Appendix


29/32-29-


7-2 LVDS Circuit(1) LVDS Interface

For transmitting the video signal information, an interface circuit with an LVDS (Low Noise Different

Signaling) standard is used, which has the merit of low noise, high speed operation by a small amplitud

and low power consumption.

The LVDS cable connects the transmitter in the driving circuit and the receiver in the module.

(2) Driving Circuit

Fig. 32 shows the block diagrams of a panel driving circuit. The final video information (signal) from th

video processor (for example pixelworks) is transmitted to the LCD panel module through an LVDS cabl

1.2V 345/200mV

100

Terminated3.5mAReceiver

(LCD Panel)Transmitter

(Driving

Circuit)

LVDS Cable

Fig. 31 LVDS Interface

BLANK

PARITY

PDWN

DATA (LVDS)

CLOCK (LVDS)

RxOUTRxINTxOUTTxINR 8

G 8

B 8

R 8

G 8

B 8

VsyncVsync

Hsync

VsyncVsync

Hsync

DCLK

BLANK

PARITY

RxCLKOUT

DCLK

TxCLKIN LVDS

LVDS Transmitter LVDS Receiver

VideoProce

ssor(pixelworks)

LC

D

Module

Part of (Panel) Driving Circuit Part of Panel Display (in the module)

Fig. 32 Block Diagrams of Panel Driving Circuit

Appendix


30/32-30-


CXA2089Q

AV Switch U46

U36

U30

U45

U101

TU201

U44

U19

CVBS_

OUT

L_

OUT

V_

TV

R

_TV

L_

TV

R_

OUT

S1 S

Y1

SC1

Monitor Output

AV1 Input AV2 Input

Video Decoder

VPC3230D

TMQJ8

Tuner / IF

PIXELWORKS

PW113-10Q

M37272M6

Sub CPU

IIC+CONTROL

Tuner Board

Main Board

Audio Processor

NJW1138M

LA4263

Audio AMP

R L

Headphone (J26)

R

L

R

L

Main Scaler / (Main)CPUVY [0-7]

VUV [0-7]

DGO [0-7]

DRO [0-7]

DBO [0-7]

LCD Panel

S_CLK / SIN_OUT/ ENABLE_IN / ENABLE_OUT

Speaker (R)

Speaker (L)

LV R LVS

R LV R Y Cb Cr

8Mbits

Flash ROM

MENORYDATA

CVBS1

L1

R1 C

VBS2

L2

R2

ComponentD-SUB

SEL

ECTED_

Y

INP

UT_

Y

INPU

T_

Cb/Pb

INPU

T_

Cr/Pr

SEL

ECTED_

C

CVB

S

AUDIO_

R

AUDIO_

L

VCPU 33/18

VCPU 33

V33D

+9V16

6717

+12V

4

+9V34

323033

47

43 4539

301

1

3

238

108

41

717472 5 4 6

40

48 46

1198427 3 5 1

3

2

1

37

CC_R

CC_G

CC_B

U6

IC1

PC Input

AD9883

Graphic A/D

RXIN+/-[0-3]

RXCLK+/-

Red_

PC

HS_

PC

G_

PC

VS_

PC

B_

PC

L_PC

R_PC

V33

V33D

AVDD

PVDD

54 30 3148 43

18

16

GRE

[0-7]

GGE

[0-7]

GBE

[0-7]

RH

G BV

THC63LVDM83A

LVDS

Interface

7-3 Block Diagram Example

(1) CLT-1583

Appendix

(2) CLT-2053

CXA2089Q

AV Switch U46

U36

U30

U45

U101

TU201

U44

U19

CVBS_

OUT

L_

OUT

V_

TV

R_

TV

L_

TV

R_

OUT

S1 S

Y1

SC1

Monitor Output

AV1 Input

AV2 Input

AV3 Input

Video Decoder

VPC3230D

TMQJ8

Tuner / IF

PIXELWORKS

PW113-10Q

M37272M6

Sub CPU

IIC+CONTROL

Tuner Board

Main BoardAudio Processor

NJW1138M

LA4263

Audio AMP

R L

Headphone (J26)

R

L

R

L

Main Scaler / (Main)CPUVY [0-7]

VUV [0-7]

DGO [0-7]

DRO [0-7]

DBO [0-7]LCD Panel

S_CLK / SIN_OUT/ ENABLE_IN / ENABLE_OUT

Speaker (R)

Speaker (L)

LV R LVS

R LV R L R Y Cb CrAudio

Board

8Mbits

Flash ROM

MENORY

DATA

CVBS1

L1

R1 C

VBS2

L2

R2

L3

R3

Component

SELECTED_Y

INPUT_

Y

INPUT_

Cb/Pb

INPUT_

Cr/Pr

SELECTED_C

CVBS

AUDIO_

R

AUDIO_

L

VCPU 33/18

VCPU 33

V33D

+9V16

6717

+14V4

+9V34

323033

47

43 4539

301

1

3

238

108

41

717472 5 4 6

40

48 46

18

16

1198427 3 5 1

3

2

1

37

CC_R

CC_G

CC_B

Fig. 33 Block Diagram: CLT-1583

Fig. 34 Block Diagram: CLT-2053


31/32-31-

Training Manual Principle of LCAppendix

(3) CLT1554 / CLT2054

AV1

Composite Video

S VideoAV1_CV 1

Video SW

Audio SW

Audio Control

Surround

Audio

AV2

IC1001

Composite Video

Audio

AV3

Component Video

Audio

TV (A201)

Tuner

IF

Sound Multiplex

IC001

Audio AMP

IC101

Video SW

IC1002DD Converter

IC871

SDRAM

IC361

LVDSTransmitter

IC781

LCD PANEL

(20V)

A/D Converter

IC4101

Sync Separation

IC1701

Digital Decoder

with

Y/C Separation

IC2001

CPU

(480i)

(For 20V)

(For 15V)

IC801

IP Converter

Screen Controller

IC301

AV1_Y

AV1/TV_Y/CV

DEC_Y/C (0-7)

(Y/UV)

3

AV1_C 90 85

AV3_Y 3

AD_Y 26

AV3_Cr 92

AV2_V 1

AV1_L/R L: 30R: 1

AV2_L/R L: 29R: 2

AV3_L/R L: 28R: 3

TV_L/R L: 27R: 4

TV_CV 5

5

7

AD_HS16

30AD_VS

28

31

OSD_HD

154

22 VD

OSD_HD

OSD_CC

VD

153

23 18R

152R

151G

150B

148Y

149I

19G 20B 21Y 16I12 10

13 11

7

36 37(For Caption)

SEL_Y/CV

10 SEL_R

16 R-OUT (+)

15 R-OUT (-)

21

13

9SEL_L

AV3_Cb 94

(480p)

AD_Cr 54

AD_Y 48

AD_Cb 43

IIC Bus

IIC Bus

IIC Bus

IIC Bus

IIC Bus IIC Bus

AD_R/G (0-7)

R/G/B (0-7)

R/G/B (0-7)

AD_CLAMP

15

38

3.3V

5V

LCD PANEL

(15V)

SPEAKER

(Right)

24 L-OUT (+)

25 L-OUT (-)SPEAKER

(Left)

Fig. 35 Block Diagram: CLT1554 / CLT2054


32/32

Documents

Sanyo LCD Training Manual