LED and LCD Panel Training

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 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.

4unit CCFL small size LCD TV

Lots of CCFL big size LCD TV

CCFL Parameters Parameter

Values

Symbol

Unit

Min

Type

Max

Operating Voltage

VBL

655

685

805

VRMS

Operating Current

IBL

3.0

5.0

6.0

mARMS

Starting Voltage(at 0 C)

Vs

1370

VRMS

Operating Frequency

FBL

58

80

kHz

Power Consumption

PBL

3.43

3.77

Watt

45

Inverter parameters(size:24) Item

symbol

value

unit

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

灯管电流lamp current

Ilamp

mArms

3.0

工作电压 Operating voltage

Vlamp

Vrms

启动电压 Start-up voltage

Vopen

Vrms

启动时间start-up time

Ts

S

5

7.5

8.0

700

880

remark

Anode or cathode dimming

I lamp=7.5mA

1250

Ta = 25 ºC

1650

Ta = 0 ºC

1

3

CCFL Operate Voltage Waveform •

765V

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

Block Inverter Diagram

Input

Brightness adjustment

CCFL and LED Dimming CCFL dimming pricinple(Analog mode)

LED dimming pricinple(PWM mode) Vadj

Vadj

out

fb

inverter

fb

Imax Imax

inverter

Duty Duty

Vadj

cycle regarding large dimming

cycle regarding large dimming

fb

Vadj

out inverter

Duty

out

cycle regarding small dimming

fb

out inverter

Imax

Duty

cycle regarding small dimming

Imax

LED Chip Structure

LED Chip Structure

White LED structure

Large area phosphor layer From LED

From 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

600.00 500.00 500.00 400.00

CCFL

400.00

LED

300.00

300.00

200.00

200.00

100.00

100.00 0.00 1 1723435146858561027 1198 1369 1540 1711 1882 2053

0.00 1 38 75112149186223260297334371408445482519556

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

LED CCFL

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 In for Inverter

Data In (LVDS)

Backlight inverter

Timing Controller

Lamps

RSD S

Gamma Reference Voltages

Power In for signal

Power Converter (DC/DC Converter)

Gate Drivers

Source Drivers

TFT-LCD Panel

Vcom

Timing Controller  SSC : Spread Spectrum Clock EEPROM Input Signal  DE Mode Only  RGB 24bit Data  Clock

L V D S

SSC

Data Controller

LVDS Rx

ACC

T x PLL

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

DCC

RSDS Rx

Front RSDS Data

RSDS Rx

Back RSDS Data

T-CON

Memory Controller

Memory (DDR)

Control Signal & Gate Signal

LVDS Signal Format LVDS Signal

RxIN0

RxIN1

RxIN2

RxIN3

Input Data RxOUT0 RxOUT1 RxOUT2 RxOUT3 RxOUT4 RxOUT6 RxOUT7 RxOUT8 RxOUT9 RxOUT12 RxOUT13 RxOUT14 RxOUT15 RxOUT18 RxOUT19 RxOUT20 RxOUT21 RxOUT22 RxOUT24 RxOUT25 RxOUT26 RxOUT27 RxOUT5 RxOUT10 RxOUT11 RxOUT16 RxOUT17 RxOUT23

VESA R0 R1 R2 R3 R4 R5 G0 G1 G2 G3 G4 G5 B0 B1 B2 B3 B4 B5 HSYNC VSYNC DE R6 R7 G6 G7 B6 B7

JEIDA R2 R3 R4 R5 R6 R7 G2 G3 G4 G5 G6 G7 B2 B3 B4 B5 B6 B7 HSYNC VSYNC DE R0 R1 G0 G1 B0 B1

Resolution of LCD TV Resolution

Aspect Ratio

No. of Pixel

Panel Size

15:9

1280 x 768

17”, 19”

16:9

1366 x 768

23”, 26”, 32”, 40”, 46”

16:9

1920 x 1080

40”, 46”, 5X”

HD

FHD

Input Timing  Resolution : 1366 x 768 Signal

Item

Symbol

Min

Typ

Max

Unit

Fclk

60

80

85

MHz

Fh

43

50

53

KHz

Fv

48

60

66

Hz

Display period

Thd

-

1366 (1280)*

-

Clocks

Total

Th

1368

1600

1800

Clocks

Display period

Tvd

-

768

-

Lines

Total

Tv

773

838

1200

Lines

Clock Hsync

Frequency

Vsync

Horizontal timing

Vertical timing

Input Pins Assignment  Connector: DF14A-20P-1.25H(HIROSE) or Compatable  Model : 17”, 19”, 23” - HD No

Signal

No

Signal

1

Vin(+5V)

11

GND

2

Vin(+5V)

12

Rclk-

3

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

LVDS cable

 LVDS Format Option High : VESA, Low : JEIDA

Input Pins Assignment No

Signal

No

Signal

1

N.C(#1)

16

GND

2

N.C(#2)

17

Rx3-

3

N.C(#3)

18

Rx3+

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)

 Connector: FI-E30S(JAE) or Compatible  Model : 23”, 26”, 32”, 40” - HD

LVDS cable

 LVDS Format Option High : VESA, Low : JEIDA

Input Pin Assignment 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

 Connector: FI-E30S(JAE) or Compatable  Model : 40”, 46 - FHD

LVDS Cable

Input Pin Assignment(Inverter)  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

Inverter cable

 B/L On/Off 3.3V : On, 0V : Off  Analog Dimming 3.3V : Max, 0V : Min  PWM Dimming Duty 30% : Min, Duty 100% : Max

Inverter Specifications 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

LED Backlight Driving Principle Control Signal

LCD Driving Circuit

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

Power Sequence

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

TCL 26D20 LED drive circuit 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

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

MP3389’s Circuit

LED Panel Structure Introduction Open cell

Front LCD PANEL

Take care braket Panel serial NO. Source board

1 Inverter board

T-con boar d

2

prim sheet(vertical) prim sheet(horizontal)

3 Take care Tape Carrier Package

protection sheet

4

Diffuser sheet

CCFL’S Socket Fromt mounting bracket

After taking out open cell,we can see protection sheet

Cable

LED Panel Structure Introduction LED panel

Front mounting bracket

After taking out open cell,we can see protection sheet

protection sheet

1

Panel Serial NO.

prim sheet(vertical)

2

prim sheet(horizontal)

3

Diffuser sheet

4

LED poower supply socket

Open cell Inverter board

T-CON board

LED lamp Flexible printed cable

Backlight Structure Introduction

LED Panel Module 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

The Others Introduction Front cabinet

Panel

Power supply board

Main board

Front cabinet

Panel

Power supply board

Main board

Open cell The other LCD TV structure Stand base component

Rear cabinet

Common LCD TV structure

Backlight module

Rear cabinet

Open Cell Structure

Source PCB+Gate PCB Source TCP

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

Working Instruction of The Panel Reflector sheet

Assembly protection sheet\prim sheet(two \diffuser sheet

Connect ground cable

Assembly bracket

Bring open cell to assembly

CCFL bracket

Assembly protection sheet\prim sheet (two\diffuser sheet

Check here it is ok or not Put the open cell on the backlihgt module

Assembly CCFL ,take careCCFL not breaking Take care source gate board Take care :ccfl and socket connect

Check panel it is ok or not

Finishing assemblying backliht module Take care flexible printed cable

Tool’s moving opencell

LCD Trouble Shooting （2）

CCFL is not light

Check power N supply board

Check power supply V=24V or 12V Y

N Check backlight on/off

Y N

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

Check main board Check backlihgt board

CCFL flash

Check power supply V=24V

N

Check power supply board

Y Check Vblihgt-dimming or dimming

N

Y Check Vtcon?(powersupply of T-con board Vt-con)

N

（1）

Y Check backlight board

Check main board

LCD Trouble Shooting CCFL is light and then not light

Check power supply board

N

Check power supply V=24V or 12V

Y

Check main board

N

Y Check backlight on/off

check CCFL or connect to CCFL cable or socket Y Check backlight board

N checkCCFL or cable

LCD Trouble Shooting CCFL is light to keep 2S,and then is not light N Check transformer’s feedback circuit

N Check CCFL’S socket or plug

Check CCFL socket Check OPC’s circuit

Y

Check PWM’s OPV and feedback circuit

Y

N

Y Check transformer or feedback circuit

Check transformer’s voltage

N

N

Y Y Check OPV and OPC’s circuit

Replace PWM IC

Check transformer or capacitor

Check MOS’S circuit and feedback circuit

What is LVDS?

picture

 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? ▶ 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

LCD Module

Data(LVDS)

Host System Graphic Controller

CMOS/TTL

CMOS/TTL

T-con Clock(LVDS)

LVDS Tx

LVDS Rx

CMOS/TTL Interface Data 24 line Control 3 line Clock 1 line

CMOS/TTL Interface LVDS Interface Data 4pair + Clock 1pair = 10 line

Data 24 line Control 3 line Clock 1 line

LVDS Signal Mapping

What is RSDS? ▶ 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

ONLY 24 Data Lines, RSDS (200mV) @ 80MHz

RGB Data(RSDS) Timing Controller

RSDS Tx

Timing/ Control

N Source Column Driver

........

Clock(RSDS)

RSDS Signal Mapping

Timing Control

Row Driver

. .

RSDSCLK

NN Source Column Driver Driver

- LCD TFT PANEL

Row Driver

DIO RSDS00

D0 D1

D0 D1

D0 D1

D0 D1

D0 D1

RSDS01

D2 D3

D2 D3

D2 D3

D2 D3

D2 D3

picture

Appendix 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 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.