LCD Driving Principle and Driving Circuits

LCD Driving Principle and Driving Circuits

LCD Driving Principle and
Driving Circuits
Speaker: Wenbinchen
Date: 2011/3/24
Outline
LCD Driving Principle
LCD Structure
Basic Operation
Driving method
LCD Driving Circuits
Driving Circuits Structure
Gate Driver
Source Driver
Outline
LCD Driving Principle
LCD Structure
Basic Operation
Driving method
LCD Driving Circuits
Driving Circuits Structure
Gate Driver
Source Driver
LCD Structure
LCD Structure
LCD Structure
LCD Structure
Basic Operation --- TN
亮態
暗態
解偏板
出射光之
極化狀態
電場
液晶分子
偏光板
液晶是受電場影響
而扮演光閘的角色
背光源
那電場是如何產生
未加電場狀態 的呢……….
加電場狀態
Basic Operation --- TN
90º
Polarizer
LC
Voltage
Polarizer
Transmittance(%)
100
90
Back Light
10
0.0
Voltage (Between Vcom & Pixel)
Basic Operation --- TN
(data line流至pixel ITO之電流)
Cst
Id
10E-6
Vg < -3V, TFT
turn off
Data line 訊號
無法送至
Pixel ITO
Pixel ITO
(Display area)
Vg > 5V, TFT turn on
Data line 訊號可送至
Pixel ITO
10E-11
10E-12
Data Line
-10
-5
10
20
Vg
(Gate 電壓)
TFT元件特性
Gate Line
TFT
Pixel 架構示意圖
可利用Gate line 電壓的不同,控制TFT
是否turn on.進而決定data line訊號能否
輸入pixel ITO
Driving Method
面板是由Gate_Line與
Data_Line組成的一個矩陣結構
Gate Line
Sub_Pixel
Data Line
Driving Method
Voltage
G1
T= 0
G2
t=0
Selected
row
Nonselected
row
t=1
time
Driving Method
Gate_Line：Scan
讓每一“行”的pixel有“時序性”的被
控制
T= 1
NonSelected
row
Selected
row
Driving Method
以一個畫面來看…
Gate line driving waveformData line driving waveform
Voltage
Frame Time
Voltage
V64
G1
Data Line 1~N
G1
G2
G2
G3
G3
GN
G1
Time
t1 t2 t3
tN t1
Driving Method
AC driving instead of DC
driving
If DC driving……..
Pixel Charging Behavior
Considering the related capacitance in pixel
holding state
Signal n-1
Signal n
Gate n-1
C lc
C pd’
C st
C pd
Gate n
C gs
CF ITO
TFT
Pixel Charging Behavior
Signal M-1
Signal M
Gate N - 1
Gate N-1
Gate N
Pixel MN
Signal
M
Gate N
Pixel
MN
Charging
Pixel Charging Behavior
Vgate(n-1)
Vgate(n)
1/1000
Gn-1
Gn
999/1000
Pixel charging : 1/1000
Pixel holding : 999/1000
Vgate(n)
Vgate(n-1)
Vdata
VPixel
Vcom
Pixel Charging Behavior
Vgh
C pd(next)
Vpixel(p)
Vcom
Vpixel(n)
Vgl
C st
C pd(own)
C lc
C gs
On
Off
Pixel Charging Behavior
Vgh
C pd(own)
Vpixel(p)
Vcom
Vpixel(n)
Vgl
C st
C pd(next)
C lc
C gs
On
Off
Pixel Charging Behavior
Vgh
就是這東西叫Feed-Through
Feed through Voltage
C pd(own)
Vpixel(p)
Vcom
Vpixel(n)
Vgl
C st
C pd(next)
C lc
C gs
On
Off
Outline
LCD Driving Principle
LCD Structure
Basic Operation
Driving method
LCD Driving Circuits
Driving Circuits Structure
Gate Driver
Source Driver
LCD Structure
DC/DC
Y-Driver IC
DC/DC
converter
Receiver
Connector
Connector
ASIC
Timing
Controller
RSDS/TTL
Transmitter
VGA &
Scalar
Source Driver
Gamma
Correction
Power
Transmitter
Timing controller
Cell
X-Driver IC
X PCB
Gate Driver
:XPCBA
Driving Circuits Structure
Signal flow
DC/DC
Driving Circuits Structure
• AVDD = (0.2 + 3.8 + 0.2)*2 = 8.4V
V0
V1
7.6V
3.8V
V6
4.31V
Vcom
TRANSMISSION
V7
3.29V
3.8V
V8
V13
AVDD decides maximum driving voltage of LC
0V
VOLTAGE
Driving Circuits Structure
Column Driver
Row Drivers
Gate
Source
Vgh
Drain
Vgon-min
Tg
Vgpp
Vgd
Vspp
Vgdholding
Vgh/Vgl depend on TFT pixel charging and
Vst:影像訊號的直流位準
Vsh
Vdh
Vst
Common
Vsl
Vdl
Vgoff-min
Vgl
Gate Driver---Functional Block
Level shift
Logic
Shift register
Logic output = ( Din and OE ) or (not XON)
Gate Driver---Shift Register
YDIO1
D
Q
D
CLK
Q
D
CLK
Q
D
CLK
Q
D
CLK
Q
D
CLK
CLK
YCLK
Out 1
Out 2
Function of shift register
Out 3
Out 255
Out 256
Q
YDIO2
Gate Driver---Level Shifter
VGH
When logic output=1
Gate1 open
gate1
(Vgh,Vgl)
Analog output
(1,0)
When logic output=0
Gate2 open
gate2
VGL
Function of Level shifter
Source Driver---Functional Block
Y2
Y383
Y1
Y3
Y382
Y384
Output Buffer (384 Channels)
VGMA1 ~
VGMA14
6
6
6
DATAPOL
6
6
6
Data Register
6
6
6
6
6
6
6
6
6
6
Line Latch ( 384 X 6 Bit )
STB
6
1
CLKP
CLKN
128
SHL
128-bit Shift Register
DIO2
DIO1
DVDD
6
Level Shift
RSDS Receiver
D00P/N
D01P/N
D02P/N
D10P/N
D11P/N
D12P/N
D20P/N
D21P/N
D22P/N
POL
R-DAC
DGND
AVDD
AGND
Source Driver---R-DAC
B0
B0
B1
B1
B2
B2
VGMA1
R0
VGMA2
R1
VGMA3
R2
VGMA4
OP
R3
VGMA5
R4
VGMA6
R5
VGMA7
R7
VGMA8
+
Quiz #2 (請註明英文專有名詞)
1. LC driving 中 LC mode 分為三類，試說明之?
2. 試計算Full HD TV之水平與垂直解析度為1920x
1080 共有多少個次畫素?
3. 試說明四種畫素充電(Pixel charge behavior)之極性
反轉的方式?
4. 若一面板驅動有feed through voltage，你認為畫素
電壓會出現何種現象，試繪圖說明?
5. 承第二題之解析度，若聯發科設計之一顆水平方
向的驅動IC有1440通道(Channel)，請問水平方向
之驅動IC個要幾顆?
6. 一道光罩之Array Process主有由哪三種製程組成?