STN LCDs ????

1
???????????

• ????
• ??????
• ???????
• ????????
• STN LCDs ????
• TFT LCDs ????
• ??TFT LCDs ???????
• Driver IC ??
• TFT LCDs ?????????

2
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??
??
??
??
????
??
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3
???????
4
???????
Crystalline
Liquid Crystalline
Liquid
K SmC SmA N
L
Biaxial
Unaxial
Isotropic
Temperature
5
?????
6
???????

• ??? (Anisotropic)
• ???? ( )
• ??? ( )
• ???? ( )
• ???? ( )
• ????
• ???
• ???? ( )

7
???????
Helical Axis Optical Axis
Optical Axis
Optical Positive
Optical Negative
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??????
??
??
??
Field OFF
Field ON
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??????????

• ??
• ??????
• ??????
• ???,????
• ????????
• ??????
• ??
• ?????
• ???????????
• ?????????

10
????????
??? (Twinst Nematic, TN) 1971 ???? (Super Twinst
Nematic, STN) 1984 ?????? (Double Layer
STN, DSTN)1987 ????????? (Film STN,
FSTN)1988 ???????? (AASTN or MLS STN)
1992 ???? (Ferroelectric Liquid Crystal FLC)
1980 PDLC (Polymer Dispersive LC) 1988
PSCT (Polymer Stabilized Cholesteric Texture)
1993 Other DS (Dynamic Scattering) 1968
PC (Phase Change) 1968 GH (Guest
Host) 1968 ECB (Elcetrical Control
Birefregency) 1971 BTN (Bistable Twist Nematic)
1995 IPS (In Plane Switch) 1995 VA (Vertical
Alignment)1996
?? ???
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TN ? LCDs ????
Field OFF
Field ON
????
?????????
????????? ??????
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STN LCDs ????
Field OFF
????
???????? ????????
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TN STN ??????V-T Curve
T
Vs TN
Vns TN
100
90
10
V
Vns STN
Vs STN
14
TN ? STN ?????
T
STN Mode
100
V
15
LCDs ????

• ????? (Direction Addressing)
• ????? (Static Addressing)
• ????? (Multiplex Addressing)
• ????? (Active Addressing / Multi-Line Selection)
• ??????? (Active Matrix Addressing)
• ???? (MIM, Diode..)
• ???? (A-SiH TFT, Ploy-Si TFT ..)
• Plasma Addressing (PALC)
• ?????? (????)
• ?????? (?????

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LCDs ?????
ON
OFF
Vsig
Vc
Vs
Vc-Vs
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????? (???????, APT)
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????????
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APT ????
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IAPT ????
APT Addressing
IAPT Addressing
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APT ? IAPT ????

• APT Addressing
• Low Voltage Segment Driver 2D
• High Voltage Common Driver 2F
• IAPT Addressing
• Offset D for Positive Polarity
• Offset F for Negative Polarity
• Voltage Range of Segment Driver FD
• Voltage Range of Common Driver FD

22
??????????
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STN LCDs ??
Operation Voltage Vop
Bias Ratio
Steepness
Selection Ratio
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STN LCDs ??????
If Voff2V, N240 rows, Then
APT Segment Driver 2.96V, Common Driver
44.40V IAPT Segment Common Drivers 23.68V
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STN LCDs Drivers ??
??????
(HLHL...H)
......?????(Shifter Register)
DCLK
????
LP
...?????(Latch Register)
H
L
H
H
FD
?
0
?
............................
F-D
?
2D
?
............................
IAPT ?? IC
DF
............................
IAPT ????
??????
2D
0
2D
2D
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???? - FRC

• Frame Rate Control, FRC

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???? - PWM

• Pulse Width Modulation, PWM

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???? - PHM

• Pulse High Modulation, PHM

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???????
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Vertical Crosstalk of STN LCDs
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Vertical Crosstalk ??? (?)
????????????????
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Vertical Crosstalk ??? (?)
????????
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Vertical Crosstalk ??? (?)
??????????????????, ??????????????????, ??????????
????????
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Horizontal Crosstalk of STN LCDs
A
B
A
B
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Horizontal Crosstalk ???
A
B
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Frame Response of STN LCDs
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Active Addressing for STN LCDs
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Active Addressing ????

• If Voff2V, N240 rows, Then
• F 0.730 X 2V 1.460V
• G 0.954 X 2V 21.909V
• Output Range of Segment Driver
• is about 44V.
• Common Driver of Common Driver
• is about 3V.

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Segment Voltage of Active Addressing
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Active Addressing ?????
???(Row)
?(Column)
???(Column)
??(Time)
??(Time)
Bit-Map Image Matrix
Column Voltage Matrix
Row Function Matrix


41
??????
???(Column)
?(Column)
???(Row)
??(Time)
Time Dtk
Bit-Map Image Matrix
Row Vector


?????? Column Sequential
?j?
?(Column)
???(Row)
???(Column)
Column Vector
??(Time)
?(Row)
Row Function Matrix


?????? Time Sequential
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Column Sequential ????
43
Time Sequential ????
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??????????AM-LCDs
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TFT LCDs ????
Column Driver
Row Drivers
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Arrangement of Color Filter
Stripe
Triangle
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Pixel Structure of TFT LCDs
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Cs on Common ? Cs on Gate ??
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Timing Chart of TFT LCDs
Time
Gate 1 2 3 N
Frame Time
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TFT LCDs Driving Method
Row Inversion
Frame Inversion
Column Inversion
Dot Inversion
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Direct Driving of TFT LCDs
GrayScale Voltage
DC Bias of Common
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AC Modulation Addressing of TFT LCDs
Graylevel Voltage
Common Waveform
1Frame / 1 Line
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TFT LCDs ?????Direct Addressing
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TFT LCDs ?????AC Addressing
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TFT LCDs Driving Waveform Cs on Common (?)
TFT LCD ???? (Cs on Common, Common DC Bias)
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TFT LCDs Driving Waveform Cs on Common (?)
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TFT LCDs Driving Waveform Cs on Gate
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TFT ???????
59
???????

• ???? CLC ??????????????,????????????? DC
  ??,???????
• Image Sticking.
• Picture Flicker.
• ????????,??????????????
• ????????,??????????????

60
?????????
Vs
??????
Ch(N-1)
??????
Vg
Vct
Cs
Clc
Csd
Cgs
Cgd
Ch(N)
??????
Vg
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TFT ?????
4 Level Addressing
3 Level Addressing
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3 Level Addressing
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4 Level Addressing
B()
???
W()
B()
W(-)
?Vp()
B()
W(-)
CsVge(-)/Ct
???
VstVct
?VpCgdVghl/Ct
???
CsVge()/Ct
W(-)
B(-)
W()
?Vp(-)
B(-)
W()
CtCsClcCgd
???
B(-)
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Cs on Gate ??????
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Comparsion of Addressing Method
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Horizontal Line Crosstalk
A
B
Color Filter Substrate
Csc
Csc
Csc
TFT Substrate
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Horizontal Area Crosstalk
A
B
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Vertical Area Crosstalk
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Shading Crosstalk
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Shading Crosstalk ???
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Gate Pulse ?????

• Gate (Scan) Line ???????????? RC ??,?? Gate Pulse
  ?????????????????

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??????????(?)
Reverse Tilt
????
VP
VL
VA
????
????
Reverse Tilt
VA lt VL Disclination Appeared VA gt VL
Disclination Disappeared VP gt LC Threshold Voltage
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??????????(?)
???? 1.??????? ???(Pretilt Angle) 2.?? Black
Mask ? ????
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?? IC - Scan Driver
STVR
STVL
STVR
CPV
VDDD
Bidirectional Shift Register
R/L
VSSD
G1
VDDA
Level Shift Circuit
G2
VSSA
Gx
Output Buffer
STVL
G1 G2 G3 ...
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Serial In - Serial Out Analog Data Driver
Multiplexer
Sample and Hold
ProVery simple. Fewer external
connections. ConMany analog inputs.
Reduced pixel charging time. System Note
Sample clock (Dot clock) / N, N Phases.
Video Phase N
Variation on Multiplexer ProVideo
Input. ConFast data line charging needed.
Reduced pixel charging time. System Note
Shift Clock (Dot Clock) / 3 for Mono.
Video Phase 3 for Mono.
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Serial In - Parallel OutAnalog Data Driver (?)
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Serial In - Parallel OutAnalog Data Driver (?)
Double Sample and Hold / Multi-Phase
Por Reduced operation frequency . System Note
Video In N Video Phase N Shift Clock (Dot
Clock) / N.
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Digital Data Driver (?)
Digital-to-analog Converters
Sampled Ramp
Ramp In
Por Digital input. Con Complex.
Requires sufficient precision to
correct for LC response variation.
Por Digital input. Programmable
ramp. Con Complex circuit. High speed
digital circuits. Reduced pixel
charging time.
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Digital Data Driver (?)
1-of-n Selector
Simple DAC Pro Digital input.
Programmable external voltages. Con Complex
circuit. High speed digital circuits.
Many pass gates per data line.
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Digital Data Driver (?)
All Digital Circuit
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Gamma Correction of LCD
Analog Correction 2 3 Segment
Approach. Digital Correction External fixed
voltage.
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Gamma Correction Simple Case
Transmission
Voltage
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The Block Diagram of the TFT LCD Module
84
The TFT LCD Module Type

• Classified into two kinds by data driver
• Analog type TFT-LCD module
• The analog data drivers
• The analog interface to PC
• Only NEC
• Digital type TFT-LCD module
• The digital data drivers
• The ADC/ LVDS/PanelLink interface to PC
• Mainstream

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The Analog Interface
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The ADC Interface
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The LVDS/PanelLink Interface
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Analog/ADC/LVDS/PanelLink

• Analog Interface
• True Color
• Sampling Error
• Low Edge Sharpness
• Noise in the Analog Signal Transmission

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Analog/ADC/LVDS/PanelLink

• ADC Interface
• Mainstream in the Desktop LCD Monitor Interface
• Sampling Error
• Low Edge Sharpness
• Noise in the Analog Signal Transmission
• EMI Issue for High Resolution Format
• Low Image Quality and High Cost

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Analog/ADC/LVDS/PanelLink

• LVDS Interface
• Mainstream in the Notebook PC Interface
• High Edge Sharpness
• Reducing EMI Number of Cable Line
• High Image Quality and Low Cost
• Short Transmission Length Low Noise Margin
• Compatible Issue

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Analog/ADC/LVDS/PanelLink

• PanelLink Interface
• Application in the Desktop LCD Monitor Interface
• High Edge Sharpness
• Reducing EMI Number of Cable Line
• High Image Quality and Low Cost
• Second Supply Source Issue

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TFT Module ????(?)

• ???????????(Image Format)
• ?????(Frame Rate)
• ?????????
• TFT ? ION/IOFF ??
• ???????RC????
• ????
• ????

93
TFT Module ????(?)

• ?????????(Cs on Gate or COM)
• ???????????
• ??IC(Scan Source)???
• TFT LCDs ?????????

94
??????? TFT LCDs ????????
95
Plasma Addressing LCDs
96
In-Plane-Switch Mode LCDs
97
Vertical Alignment Mode LCDs
???
???
???? ????
????
????
???? OFF ??
???? ON ??
???
???
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Comparison of Liquid Crystal Modes
TN
IPS
VA
Off(Black) On(White)
Slightly dependent on viewing angle
???
???????
?????
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