TCL LED and LCD Panel Training Schematic

Training Manual of Panel

(CCFL & LED)

CCFL Lamps Appearance

U-shapes lamps

straight lamps

M-shapes lamps

Inverter Board

Power supply voltage board and
inverter board is one PCB

Inverter board

TFT-LCD Imaging Principle

1:Scan IC transmission signal

2:Driver IC transmission imaging control signal

3:When one sub-pixel cut-off, the sub-pixel cannot get light to show black.

4:If sub-pixel cut-off ,but light through the color filter and display color

5:After the synthesis of light effects, the display can produce color effects.

Color filter

enlarge

TFT-LCD Imaging Principle

TFT-LCD Imaging Principle

CCFL backlight LCD TV

4unit CCFL
small size
LCD TV

Lots of CCFL
big size LCD
TV

CCFL is not produce display signals , only provide light source.
Inverter board is a DC to AC converter. It is low-voltage DC convert into high-

voltage AC, and supply to light up CCFL lamps.

CCFL Parameters

Parameter Symbol

Values

Unit

Min Type Max

Operating Voltage V

BL

655 685 805 V

RMS

Operating Current I

BL

3.0 5.0 6.0 mA

RMS

Starting Voltage(at 0 C)

Vs 1370 V

RMS

Operating Frequency F

BL

45 58 80 kHz

Power Consumption P

BL

3.43 3.77 Watt

Inverter parameters(size:24)

Item symbol unit

value

remark

MIN TYP. MAX

输入电压input voltage

Vin V 9 12 16

工作频率operate
frequency

foper kHz 40 50 80

调光电压dimming
voltage

Vdim V 0 5 Anode or

cathode
dimming

灯管电流lamp current

Ilamp mArms 3.0 7.5 8.0

工作电压

Operating voltage

Vlamp Vrms 700 880 I lamp=7.5mA

启动电压

Start-up voltage

Vopen Vrms 1250 Ta = 25 ºC

1650 Ta = 0 ºC

启动时间start-up time

Ts S 1 3

CCFL Operate Voltage Waveform

• CCFL lamp light, the
voltage drop large,
sine waveform change
some distortion

CCFL operate voltage
is 765V,normal CCFL
operate voltage is
600V---800V,start
voltage is as high as
1500V—1800V

Distortion sine waveform

765V

Block Inverter Diagram

Brightness
adjustment

Input

CCFL and LED Dimming

Imax

inverter

fb

Vadj out

Duty cycle regarding large dimming

fb

Vadj

inverter

out

Duty cycle regarding small dimming

Imax

LED dimming pricinple(PWM mode)

inverter

fbVadj

out

Imax

inverter

fbVadj

out

Imax

Duty cycle regarding large dimming

Duty cycle regarding small dimming

CCFL dimming pricinple(Analog mode)

LED Chip Structure

LED Chip Structure

White LED structure

From phosphor layer

From LED

Large area phosphor layer

High Brightness LED Structure

LED Advantages

•Low power consumption

• Extremely long lifetime

• Very low early failure rate

• Smallest

• Shockproof

• Does not produce UV radiation

Or intermediate frequency
interference

• Low power

• Light through the optical lens

transmitted out

• High color efficiency

•Low voltage

LED Bar of LED TV

•By a number of independent
white LED light strip solder into
the PCB (or aluminum plate)

Installed in the frame on the
screen (the side, both sides or
multilateral)

•Light of the length and the
number of LED lamps according
to the size of screen size varies

•The LED light on the many uses
of the series (some machines will
be used in parallel or series­parallel hybrid) connected

•A single light on one or more
strings of LED

•Require specialized multi-string

LED constant current driver circuit
to drive

LED TV Structure

LED vs CCFL

• Brightness and the startup time

0.00

100.00

200.00

300.00

400.00

500.00

600.00

1 1723435146858561027119813691540171118822053

0.00

100.00

200.00

300.00

400.00

500.00

1 38 75112149186223260297334371408445482519556

CCFL

LED

LED vs CCFL

Light remote control interference

CCFL Spectrum

LED Spectrum

LED vs CCFL

CCFL：need additional start-up

high –voltage,stimulate mercury
vapor.

LED：The use of stable DC power

supply, no additional start-up high­voltage

LED TV And LCD TV Differences

• LED TV and LCD TV's biggest difference is the different use of the backlight

• LCD TV uses CCFL (Cold Cathode Fluorescent Lamp) lamps, CCFL drawback is that lifetime

is short compared with LED and CCFL using raw materials containing mercury, mercury
pollution of the environment is a big injury

• LED TV: LED backlight that is used LED lamps. The disadvantage is higher the cost of LED
than CCFL , but lifetime is longer compared than the CCFL, and the mercury-free, less
environmental damage

CCFL

LED

LED and CCFL Backlight Compare

• Environmental protection(Material does not contain mercury)

• Currently CCFL light efficiency of 60 to 100lm / w

• Currently LED light effect can be achieved about120lm / w

• Low power, Follow-up development can be achieved higher

• long lifetime(Up to 100,000 hours)

• support collor is very wide:excellent display color

• DC driver, Easy to dynamically adjust the brightness

• safety: CCFL high-voltage drivers, LED drivers only need low-voltage

• CCFL for the fragile glass products, LED chips for the semiconductor solid-state

LCD Panel Block Diagram

T-CON Board Introduction

Inverter Board Introduction

TFT-LCD Block Diagram

Power Converter

(DC/DC Converter)

Timing

Controller

Vcom

Gamma

Reference

Voltages

Source Drivers

Gate Drivers

TFT -LCD Panel

Data In
(LVDS)

Backlight

inverter

Lamps

Power

In

for

signal

Power In

for

Inverter

RSD

S

Timing Controller

LVDS

Rx

ACC

DCC

Data

Controller

Memory

Controller

PLL

T-CON

RSDS

Rx

RSDS

Rx

SSC

EEPROM

Memory

(DDR)

L
V
D
S

T

x

Front

RSDS

Data

Back

RSDS

Data

 ACC : Accurate Color Capture
 DCC : Dynamic Capacitance
 Compensation

Control Signal

&

Gate Signal

 SSC : Spread Spectrum Clock

Input Signal
 DE Mode Only
 RGB 24bit Data

 Clock

LVDS Signal Input Data VESA JEIDA

RxIN0

RxOUT0 R0 R2
RxOUT1 R1 R3
RxOUT2 R2 R4
RxOUT3 R3 R5
RxOUT4 R4 R6
RxOUT6 R5 R7
RxOUT7 G0 G2

RxIN1

RxOUT8 G1 G3

RxOUT9 G2 G4
RxOUT12 G3 G5
RxOUT13 G4 G6
RxOUT14 G5 G7
RxOUT15 B0 B2
RxOUT18 B1 B3

RxIN2

RxOUT19 B2 B4
RxOUT20 B3 B5
RxOUT21 B4 B6
RxOUT22 B5 B7
RxOUT24 HSYNC HSYNC

RxOUT25 VSYNC VSYNC

RxOUT26 DE DE

RxIN3

RxOUT27 R6 R0

RxOUT5 R7 R1
RxOUT10 G6 G0
RxOUT11 G7 G1
RxOUT16 B6 B0
RxOUT17 B7 B1

RxOUT23

LVDS Signal Format

Resolution Aspect Ratio No. of Pixel Panel Size

HD

15:9 1280 x 768 17”, 19”

16:9 1366 x 768 23”, 26”, 32”, 40”, 46”

FHD 16:9 1920 x 1080 40”, 46”, 5X”

Resolution of LCD TV

Signal Item Symbol Min Typ Max Unit

Clock

Frequency

Fclk 60 80 85 MHz

Hsync Fh

43 50 53

KHz

Vsync Fv

48 60 66

Hz

Horizontal timing

Display
period

Thd -

1366

(1280)*

- Clocks

Total Th 1368 1600 1800 Clocks

Vertical timing

Display
period

Tvd - 768 - Lines

Total Tv 773 838 1200 Lines

Input Timing

 Resolution : 1366 x 768

 LVDS Format Option

High : VESA, Low : JEIDA

No Signal No Signal

1 Vin(+5V) 11 GND
2 Vin(+5V) 12 Rclk­3 Rx0- 13 Rclk+
4 Rx0+ 14 GND
5 GNN 15 Rx3-

6 Rx1- 16 Rx3+

7 Rx1+ 17 GND
8 GND 18 GND
9 Rx2- 19 LVDS Option

10 Rx2+ 20 N.C

 Connector: DF14A-20P-1.25H(HIROSE) or Compatable
 Model : 17”, 19”, 23” - HD

Input Pins Assignment

LVDS cable

No Signal No Signal

1 N.C(#1) 16 GND
2 N.C(#2) 17 Rx3­3 N.C(#3) 18 Rx 3+
4 GND 19 GND
5 Rx0- 20 N.C(#4)
6 Rx0+ 21 LVDS Option
7 GND 22 N.C(#5)
8 Rx1- 23 GND
9 Rx1+ 24 GND

10 GND 25 GND

11 Rx2- 26 Vdd(+5Vdc)
12 Rx2+ 27 Vdd(+5Vdc)
13 GND 28 Vdd(+5Vdc)
14 RxCLK- 29 Vdd(+5Vdc)
15 RxCLK+ 30 Vdd(+5Vdc)

Input Pins Assignment

 Connector: FI-E30S(JAE) or Compatible

 Model : 23”, 26”, 32”, 40” - HD

 LVDS Format Option

High : VESA, Low : JEIDA

LVDS cable

Input Pin Assignment

 Connector: FI-E30S(JAE) or
Compatable

 Model : 40”, 46 - FHD

No Signal No Signal

1 Odd Rx0 - 16 Even Rx2 +
2 Odd Rx0 + 17 Even RxCLK ­3 Odd Rx1 - 18 Even RxCLK +
4 Odd Rx1 + 19 Even Rx3 ­5 Odd Rx2 - 20 Even Rx3 +
6 Odd Rx2 + 21 Ground
7 Odd RxCLK - 22 Ground
8 Odd RxCLK + 23

Ground

9 Odd Rx3 - 24

Ground

10 Odd Rx3 + 25

Ground

11 Even Rx0 - 26 5V Input
12 Even Rx0 + 27 5V Input
13 Even Rx1 - 28

5V Input

14 Even Rx1 + 29

5V Input

15 Even Rx2 - 30

5V Input

LVDS Cable

 Connector : S14B-PH-SM3(JST) or Compatible

No Pin Name Pin Configuration

1 Vin Typ 24V
2 Vin Typ 24V
3 Vin Typ 24V
4 Vin Typ 24V
5 Vin Typ 24V

6 GND Ground

7 GND Ground
8 GND Ground
9 GND Ground

10 GND Ground

11 NC No Connection
12 B/L On/Off Inverter Enable
13 ADIM Analog Dimming
14 PDIM PWM Dimming

 B/L On/Off

3.3V : On, 0V : Off

 Analog Dimming

3.3V : Max, 0V : Min

 PWM Dimming

Duty 30% : Min, Duty 100% : Max

Input Pin Assignment(Inverter)

Inverter cable

19” 23” 26” 32” 40”

Lamp 6 U-Lamps 6 U-Lamps 8 U-Lamps 16 Lamps 20 Lamps

Input Voltage 24V 24V 24V 24V 24V

Output Current 4.5/~ /6.5 4.0/~ /7.0 4.5/5.5/6.5 4.0/5.5/7.0 4.0/5.5/7.0

PWM Dimming 30% 30% 30% 30% 30%

Analog Dimming O O O O O

PWM

Frequency

170Hz 170Hz 170Hz 170Hz 170Hz

Lamp Frequency 60KHz 60KHz 60KHz 60KHz 60KHz

Power

Consumption

50W 70W 80W 110W 180W

Inverter Specifications

LED Backlight Driving Principle

Control Signal

It is panel ( part NO.:LC420WUE-SBA) power sequence

LCD Driving Circuit

It is panel ( part NO.:LC420WUE-SBA) power sequence

Power Sequence

TCL 26D20 LED drive circuit

26D20—MP3389 is step-up control for 12 strings LED driver

DC=24V to
DC=12V
converter

24Vconverter 38V DC-DC
and Multi-channel constant
current control output

voltage
divider
resistor

backlight
ON/OFF
control
signal

PWM
dimmi
ng
signal

MP3389’s Circuit

Fromt mounting

bracket

Panel serial NO.

After taking out open
cell,we can see
protection sheet

Take
care
braket

1

2

3

4

protection sheet

prim sheet(vertical)
prim sheet(horizontal)

Diffuser sheet

Cable

LED Panel Structure Introduction

Front LCD PANEL

Inverter board

T-con

boar

d

Open cell

Source board

Take care Tape Carrier Package

CCFL’S

Socket

LED Panel Structure Introduction

LED lamp

Inverter
board

Panel Serial NO.

T-CON
board

LED poower
supply socket

Front mounting bracket

Flexible printed cable

1

2

3

4

protection sheet

prim sheet(vertical)

prim sheet(horizontal)

Diffuser sheet

LED panel

Open cell

After taking out open cell,we
can see protection sheet

Backlight Structure Introduction

Power

supply
socket

Qty’s LED lamps:18 unit

Qty’s LED lamps:18 unit

Two LED modules are parallel

If Vinput=57V,Vone led=57/18=3.2v,so that one LED’s voltage is very low

For example:Part NO.: 4A-LCD32T-AUC panel,there are 36 LED lamp each LED unit

Two LED diodes,if one diode is defetive,the
other diode can keep LED to light,two diodes is

defetive,all LED cannot light

Solder on the PCB

LED Panel Module Introduction

The Others Introduction

Front

cabinet

Panel

Power

supply

board

Main
board

Stand base

component

Rear
cabinet

Front

cabinet

Panel

Power

supply
board

Main

board

Rear

cabinet

Open cell

Backlight
module

Common LCD TV structure

The other LCD TV structure

Gate TCP

Explain：1、Gate PCB and Source PCB and FPC in the Board

（FPC=Flexible Printed Cable ，PCB=Printed Circuit Board）

2、TCP=Tape Carrier Package

Open Cell Structure

Source TCP

Source PCB+Gate PCB

Working Instruction of The Panel

CCFL bracket

Take care flexible
printed cable

Reflector sheet

Assembly CCFL
,take careCCFL
not breaking

Take care :ccfl

and socket
connect

Assembly protection
sheet\prim sheet(two
\diffuser sheet

Assembly protection
sheet\prim sheet
(two\diffuser sheet

Finishing

assemblying backliht

module

Connect ground cable

Bring open cell to assembly

Put the open cell on

the backlihgt module

Take care source
gate board

Assembly bracket

Check here it is ok or not

Check panel it is ok or not

Tool’s moving opencell

LCD Trouble Shooting

Check power

supply V=24V or 12V

CCFL is not light

Check power

supply

board

Check backlight on/off

Check main board

Check backlihgt board

CCFL flash

Check backlight board

Check

Vblihgt-dimming

or dimming

Check main board

N

N

N

Y

Y

Y

Y

（1） （2）

N

Y

Check power

supply V=24V

Check power

supply board

N

N

Y

Check Vt-con?(power
supplyof T-con board
Vt-con)

Check Vt­con?(powersupply

of T-con board

Vt-con)

LCD Trouble Shooting

Check power

supply V=24V or 12V

CCFL is light and

then not light

Check power

supply board

Check backlight on/off

Check main

board

Check backlight

board

check CCFL or

connect to

CCFL cable or

socket

checkCCFL

or cable

N

N

N

Y

Y

Y

Replace

PWM IC

N

N

Y

Y

CCFL is light to

keep 2S,and then is

not light

Check CCFL socket

Check CCFL’S

socket or plug

Check transformer or

feedback circuit

Check transformer’s

voltage

Check OPV and

OPC’s circuit

N

Check transformer’s

feedback circuit

Check PWM’s

OPV

and feedback

circuit

Check MOS’S

circuit

and feedback

circuit

N

Y

Check

transformer

or capacitor

Y

Y

Check OPC’s

circuit

N

LCD Trouble Shooting



High Speed

—

megabits/second (Mbps) through gigabits/second (Gbps)



Low Power

—

x3.5mA current loop/output



Low Noise

—

low demands on power/ground

—

radiated electric fields tend to cancel



Low Cost

—

pure CMOS implementations

What is LVDS?

picture

Host

System

Graphic

Controller

T-con

CMOS/TTL CMOS/TTL

Data(LVDS)

Clock(LVDS)

LVDS Interface

Data 4pair + Clock 1pair = 10 line

CMOS/TTL Interface

Data 24 line

Control 3 line

Clock 1 line

CMOS/TTL Interface

Data 24 line

Control 3 line

Clock 1 line

LCD

Module

LVDS Tx

LVDS Rx

▶ LVDS(Low Voltage Differential Signaling)

- Interface between TV set and LCD module

- 340mV swing

- 7:1 Muxing

- 100 ohm R-Termination

- Reduce Data Bus Width

What is LVDS?

LVDS Signal Mapping

▶ RSDS( Reduced Swing Differential Signaling)

- Interface between T-con and Source Drive IC

- 200mV Swing

- 2:1 Muxing

- 100 ohm R-Termination

- Reduce Data Bus Width

Driver

TFT

-

LCD

PANEL

.

.

Row

Driver

Timing Control

Column

Driver

N

Column

Driver

N

Column

Driver

N

Source

Driver

N

Driver

N

Source

N

ONLY 24

Data Lines,

RSDS (200mV) @ 80MHz

Row

. . . . . . . .

RGB Data(RSDS)

Timing/
Control

Clock(RSDS)

RSDS

Tx

Timing

Controller

D0 D1

D0 D1 D0 D1 D0 D1 D0 D1

D2 D3

D2 D3 D2 D3 D2 D3 D2 D3

RSDS00
RSDS01

RSDSCLK

DIO

RSDS Signal Mapping

What is RSDS?

picture

TFT—Thin Film Transistor
LCD—Liquid Crystal Display
CCFL---Cold Cathode Fluorescent Lamp
LED-----Light Emitting Diodes

HCFL -----Hot Cathode Fluorescent Lamp
FMB ------Front mounting bracket
FPC--------Flexible Printed Cable(It is the circuit that applies to printing circuit with LC driver IC
and COG circuit interface.)
TCP--------Tape Carrier Package
BLU --------Back Light Unit
CELL------- Cell( It is the panel of liquid crystal that fill into the micro meter gap formed by
combining two glasses substrates.)
Cell gap-----Cell Gap(It is the gap between ITO film on color filter substrate and TFT
substrate.The size of the gap affects the transmittance of LCD display substrate and response
time of liquid crystal.)
CF-----------Color Filter (In order for LCD to generate colors,there is a pattern with Red,Green
and Blue,which is one of the parts in the LC cell.Color filter is structured by 4 major
components:Black Matrix to block light, pattern to display colors,transparent protection film made
from protection pattern and transparent electrode film used for driver LC).
CIE chromaticity diagram--------- CIE chromaticity diagram shows the graph of 2 dimensional
color coordinate.On the XYZ color graph and X10Y10Z10 color graph,it uses x,y or x10y10 direct
coordinate,and they are called CIE1931 color graph or CIE 1964 color graph.It is also known as

xy or x10 y10 chromaticity diagram.

Appendix

Appendix

COF-------Chip On Film(It is a simplified termof chip on film,which is a method of connecting
IC chip to the electrode terminal of flexible printed circuit board.The specialty of this IC
package method can thinner the flexible printed circuit board,which is about one third of

thickness of TCP.It also increases the reliability of the liquid crystal display module.The

current connecting processes used are:conductivity film,conductivity paste and eutectic
conjunction.)

COG-------Chip On Glass(It is a process of connecting electrode terminal of idisplay glass sub
strate and I/O of Driving IC directly to each other.The Driving IC must have bumping,and the
material used for liquid crystal substrate bumping is Au.The manufacturing process,which
uses ACF as its connecting material,is more matred.)

COP--------Chip On Plastic(It is a simplified term of Chip On Plastic,which is a method of
connecting IC chip to the electrode terminal of plastic substrate.It is used for setting the driver
IC onto the liquid crystal panel of plastic substrate.

Contrast ratio-----The ratio between the maximum and minmum brightness when the LC is
On/Off.The contrast changes with different viewing angles,and therefore,maximum contrast

ratio is used for display.Generally,STN is 10:1 and TFT is 100:1 for display.

Data line------It is the perpendicular wiring used in TFT substrate to transfer display
signals.Because it is connected with the Source electrode or Drain electrode on each pixel in
TFT,it is also known as Source line or Drain line.The width of the line is often between few um
to 10 um.

Appendix

Driver IC-------It is the IC that drives the LCD.There two types of display matrix:Scanning
electrode(column electrode)Driver and Signal electrode(row electrode)Driver.The package of
driver changes from QFP to TCP.The Driver IC of poly-silicon LCD panel forms directly in the

display screen.

Gray scale----- Gray scale is for tuning the display between maximum and minimum
brightness.When digital signal is input to it,according to2,3,4,6 and 8 bit,there are 4,8,16,64
and 256 different gray levels.Analogue input can be used for infinity level tuning display.There
are two ways of gray scale:LCD driving voltage tuning and frame rate control.

LCD Driver--------LCD Driver is for driving LC panel circuit or IC.In matrix terms,it can be

differentiated into column electrode Driver and row electrode Driver.

Scanning line------It is the horizontal wiring line,which transfers signal to the gate electrode in
TFT board,It is also known as gate line.It also has the function to select horizontal
pixels.When the pixels are selected by the scanning line,the TFT is in a conductivity
status,and signals can be written into each pixel from Data line.The signal delay in the
scanning line causes great impact to the quality of the screen image,and therefore,low resisto

scanning line should be used.