LED and LCD Panel Training

Training Manual of Panel

(CCFL & LED)

CCFL Lamps Appearance

U-shapes lamps

Inverter Board

Power supply voltage board and inverter board is one PCB

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

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

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

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 fb Vadj out Imax inverter fb Vadj out Imax

Duty cycle regarding large dimming

Duty cycle regarding small dimming

White LED structure

From phosphor layer From LED

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

series-parallel hybrid) connected •A single light on one or more strings of LED

•Require specialized multi-string LED constant current driver circuit to drive

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

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 high-voltage

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

TFT-LCD Block Diagram

Power Converter (DC/DC Converter) Timing Controller Vcom Gamma Reference Voltages Source Drivers Gate D riv ers 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 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

 Connector: DF14A-20P-1.25H(HIROSE) or Compatable

 Model : 17”, 19”, 23” - HD

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)

Input Pins Assignment



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

 LVDS Format Option

High : VESA, Low : JEIDA

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)

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

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

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

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

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

Stand base

component Rear _cabinet

Front cabinet Panel Power supply board Main board Rear cabinet Open cell Backlight module Common 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

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

Vt-con?(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?

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

▶ 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

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.