LC ModesLC Modes
이 기이 기 동
2006 07 192006. 07.19동아대학교, 전자공학과
C t tContents
1 Introduction1. Introduction
2. Liquid Crystal and Phase Retardation
3. Classification of LC Modes-. Twisted Nematic
-. Horizontal Switching
-. Vertical Switching
-. π cell
1. Introduction
DisplayDisplayDeviceDevice
LabLab FPD Application
Mobile OA TV
PJTPJT
TV 시장
LCDPJT
LCDLCD
PDPOLED
CRT-PJT
PDPOLED
10″ 20″ 30″ 40″ 50″ 60″(SIZE)
CRT-PJTFED
소형DISPLAY
N/B MONITOR
중/소형 TV대형 TV
PROJECT
출처 : J.H Kim
DisplayDisplayDeviceDevice
LabLab Principle of LCD
Light Source
LC P l
자극 분자배열변화 광학효과유발
LC Panel
전기장/자기장
Electro-Optic effect
LC Light Shutter
Image quality Moving picture, Viewing angle, Color shift출처 : J.H Kim
DisplayDisplayDeviceDevice
LabLab 주요 Display 특징비교
CRT평판 Display
기술격차는 미미해짐, 문제는 가격
CRTTFT-LCD PDP 유기EL
장점고화질
경량/박형
저소비전력박형
경량/박형
저소비전력장점저가격
저소비전력
고해상도대형크기
저소비전력
고선명/고속응답
단점부피
전자파동영상화질
가격
소비전력수명
단점 전자파
Size한계가격
소비전력
저효율/온도Size
크기(현수준) 10”~40” 2”~80” 32”~100” 40”이하
개발단계 성숙 양산/성장 양산/성장 연구개발
적용분야 모니터/TV모니터/HDTV
노트북 벽걸이TV 휴대폰/PDA적용분야 모니터/TV 노트북
휴대폰/PDA벽걸이TV 휴대폰/PDA
연구기술 평면/고정세
저가격화/대형화
응답속도개선
저가격화
고효율
기술개발(수명)양산성확보연구기술 평면/고정세 응답속도개선
광시야각확보
고효율
고해상도
양산성확보
대형화
출처 : J.H Kim
DisplayDisplayDeviceDevice
LabLab LCD Technology Trend
View AngleView AngleView AngleView AngleUniform in All directionsUniform in All directions
Response timeResponse timeResponse timeResponse timeMotion BlurMotion Blur Free Free Motion BlurMotion Blur Free Free LC + B/L + CircuitLC + B/L + Circuit
DataData
BacklightBacklight
LC + B/L + Circuit LC + B/L + Circuit
BrightnessBrightnessBrightnessBrightnessColor DepthColor DepthColor DepthColor Depth No dazzlingNo dazzling
White+White+
R G
More Natural More Natural /Peak Luminance/Peak Luminance8 bit 10 bit8 bit 10 bit
BW
■: TV2 80%0.8
1.0
② B/L Control
CRCRCRCRColor GamutColor GamutColor GamutColor Gamut
●: TV1 72%■: NTSC 100%
-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
0.0
0.2
0.4
0.6
③ Data Stretch
② B/L Control① Histogram Analysis
CRCRCRCRStatic C/R → Dynamic C/RStatic C/R → Dynamic C/RAdaptive Dynamic Image ControlAdaptive Dynamic Image Control
More Natural More Natural Pigment Pigment
2. Liquid Crystal and Phase Retardation
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
Liquid Crystals
Normal LiquidNormal Liquid
Liquid CrystalLiquid Crystal
SolidSolid
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
Li id C t l• Solid Anisotropic Liquid Isotropic• As T increases, order parameter decreases.
Liquid Crystals
Crystal: S=1; LC: S~0.6-0.8, Isotropic: S=0.
n
T
Crystal Nematic LC IsotropicRef. : S.T.Wu
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
Liquid Crystal Molecules and the Director
•• The local average direction of the molecular long axisThe local average direction of the molecular long axis
The moleculesThe molecules The directorThe director
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
The Director Field
•• There are elastic restoring forces that try to keep the director field uniformThere are elastic restoring forces that try to keep the director field uniform
ThisThisThisThis
will try to relaxwill try to relaxto thisto thisto thisto this
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
Director Configurations When Surfaces are Rubbed in Opposite Directions
No Field: High Field:
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
Director Configurations When Surfaces are Rubbed in Perpendicular Directions
No Field: Uniform twist High Field: No twist
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
• Intermediate Voltages
Director Configuration of a TN Cell• Intermediate Voltages
Near surface, directorin plane containingrub direction
Midplane directorMidplane directorin plane at 45 degreesto rub directions
Near surface, directorin plane containingrub directionrub direction
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
The Electrically Controllable Birefringence (ECB) Device
The ECB Cell
No Field: High Field: No Field: g
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
Light Propagation in Birefringent Materials
• Linearly polarized light traveling at right angles to the director:
v = c/ne
λe = λv/ne
v = c/no
λo = λv/no
DisplayDisplayDeviceDevice
LabLab2. Liquid Crystal and Phase Retardation
d
Phase Retardation
d
d
φe = 2πd /λe
φo = 2πd/λo
− φ
Δφ = φ − φe o = 2 π d ( 1 / λ e− 1 / λ o) = 2 π d ( ne - n o ) / λ v
= 2 π d Δn / λ v
3. Classification of LC Modes
Twisted Nematic : TN-. Twisted Nematic : TN-. Horizontal Switching : IPS, FFS
i l S i hi A A AS-. Vertical Switching : MVA, PVA, ASV-. π cell (OCB)
3. Classification of LC Modes
Twisted Nematic : TN-. Twisted Nematic : TN-. Horizontal Switching : IPS, FFS
i l S i hi A A AS-. Vertical Switching : MVA, PVA, ASV-. π cell (OCB)
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(1). TN Mode Cell 구성
Ref. : S.T.Wu
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(2). TN Mode 동작 animation
Ref. : S.T.Wu
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
입사한 직선편광은 액정 분자의 비틀림에 따라 편광방향이 90˚ 회전하기 때문에 직교하는
편광자를 통과하며 전압인가로 선광성이 손실되면서 빛은 차단됨
1. TN Mode
편광자를 통과하며, 전압인가로 선광성이 손실되면서 빛은 차단됨.
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(4). TN Mode – Electro optical effect
POLARIZER100
LC Configuration Electro-Optic Effect
AN
CE
(%)
60
80 R BG
GLASS
LC
TRA
NSM
ITTA
20
40
GLASS
T
0
VOLTAGE (V rms)0 1 2 3 4 5
POLARIZER
V=0 V~5Vrms
• Low operation voltage• Narrow view angle
Polarization rotation effect
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(5). Cell design - ∆nd
-. Normally White 최적 투과율 설정 Rule -. 파장대별 최적Δnd 및 실제 적용 상태 비교
최적Δnd
실제ΔndNormal TN
WV TN
( )effn dλΔ
λ
실제ΔndWV TN
Blue Green Red
point. maximumfirst ,32=
Δλnd Δnd 증가에 따른 시야각 감소.
White 영역에서 Yellowish 현상 증가.
λ×=Δ 866.0nd
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(5). Cell design – Color tracking
( )effn dλΔ
best Δnd condition
initial (Δnd)eff
λ
전압에 따른
finial (Δnd)effB G R
( )effn dλΔ
CCT
G64 G255
(∆nd)eff 증가
-. LC cell 휘도 효율 상승
-. White 색온도 감소G64 G255
전압에 따른 상관 색온도 변화
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(5). Cell design – ∆nd & Yellow shift (white state)
: Cell design 조건 - 파장 : 589nm 정면 관측: Cell design 조건 -. 파장 : 589nm-. 액정 spec.
ne = 1.5816no = 1.468
최적 Δnd
( )effn dλΔ
정면 관측
5
5.25
5.5
5.75
6최적 Δnd
case 1
case 1∆nd=410nm
5.46nmcase 2
effΓ
20 40 60 80
4.25
4.5
4.75
λ436nm 589nm 633nm
측면 관측θ
5
5.25
5.5
5.75
6
case 2∆nd=465nm
최적 Δnd
( )effn dλΔ
5.46nmΓ
20 40 60 80
4.25
4.5
4.75
5
λ
case 1
5.46nmcase 2
θ
effΓ
λ436nm 589nm 633nm
시야각 증가시 장파장 효율 증가로 Yellowish 현상 나타남.
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode
: 좌우 시야각 대칭
(5). Cell design - 주시야각
: 좌우 시야각 대칭
하시야각 High Contrast Ratio
60φ=90
120
θ= 0CR = 50
3060 30 60 0
30150
180CR 50CR = 10
210
240 300CR = 5
330
270
주시야각 방향
“상꼬하대”
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(5). Cell design – 주시야각 : TN cell 근사 해석
좌 우 상 하
Cell design 조건
파장 589-. 파장 : 589nm-. cell gap : 3.52㎛
-. 액정 spec.1 5816 1 75
2
1 75
2effΓ
ne = 1.5816no = 1.468
-. 평균 director 각: 83˚ 0.5
0.75
1
1.25
1.5
1.75
0.5
0.75
1
1.25
1.5
1.75
θ: 83
1.5
1.75
2
20 40 60 80
0.25
1.5
1.75
2
20 40 60 80
0.25
effΓ
0.25
0.5
0.75
1
1.25
1.5
0.25
0.5
0.75
1
1.25
1.5
θ
액정 평균 director 각도에 따라서 정면 retardation 값의 변화가 크다.
20 40 60 8020 40 60 80
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1
1. TN Mode(5). Cell design – gray inversion (하시야각) :TN cell 근사 해석
di t 83˚Γ
0.4
0.6
0.8
하
director : 83˚effΓ
0 8
1
20 40 60 80
0.2
θV1 V2 director : 78˚V3
effΓ
0.2
0.4
0.6
0.8
V1 V2 V3
V1>V2>V3
20 40 60 80
0.8
1
director 각 83˚ 78˚ 65˚θ
director : 65˚
with WV-A film
effΓ
0.2
0.4
0.6
θ
with WV A film
20 40 60 80
위 조건의 경우 시야각 20도 시점을 전후해서 Gray inversion이 발생한다.Mid gray 영역의 휘도는 시야각 증가에 따라 급격히 감소하는 형태를 가짐
θ
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
5
1. TN Mode(5). Cell design – gray inversion (상시야각) :TN cell 근사 해석
Γ
3.75
4
4.25
4.5
4.75
상
director : 5˚effΓ
4.75
5
20 40 60 80
3.25
3.5
θ
director : 10˚V1 V2 V3
effΓ
3.5
3.75
4
4.25
4.5
V1 V2 V3
V1>V2>V3
20 40 60 80
3.25
4.5
4.75
5
director : 15˚
θdirector 각 5˚ 10˚ 15˚
with WV A film
effΓ
3.25
3.5
3.75
4
4.25with WV-A film
20 40 60 80 θ
White 하부 계조 영역에서 시야각 증가시 inversion 현상 나타남.
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(5). Cell design – gray 통합 (좌우시야각) :TN cell 근사 해석
1.25
1.5
1.75
2
좌우
director : 83˚effΓ
20 40 60 80
0.25
0.5
0.75
1좌우
θ
1
1.25
1.5
1.75
2
20 40 60 80
V1 V2 director : 78˚
V1>V2>V3
V2 effΓ
20 40 60 80
0.25
0.5
0.75
2
θ
V1 V2 V3
계조 Black Low Gray
MidGray
Γ
0.75
1
1.25
1.5
1.75 director : 65˚director 각 83˚ 78˚ 65˚ effΓ
20 40 60 80
0.25
0.5
θ
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(5). Cell design – Film 보상 (Black Pattern)
Black 상태 LC director5
상시야각effΓ
Black 상태 LC director
1
2
3
4상시야각
4
520 40 60 80
1
4
5
좌시야각 우시야각
θ
effΓ
1
2
3
1
2
3
θ20 40 60 80
3
4
520 40 60 80
하시야각
θ
effΓ
20 40 60 80
1
2
θ
Black pattern에서 시야각에 따른 retardation의 변화가 다른 형태를 가진다.액정 director 방향을 고려한 film 설계가 요구된다.
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(5). Cell design – Film 보상 (Black Pattern)
Black 상태 LC director
Rleft > Rright Rleft ≈ Rright
By Matching tilt angle of TN LC and Discotic LC,
Enhance viewing angle characteristics of contrast and
color inversion.
( Irrelevant to Twist Angle of TN LC)
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
1. TN Mode(5). Cell design – Film 제조 (roll to roll 방식)
WV film – O modeWV film – O mode
TAC Film
연신 방향
PVA(absorption axis) TAC Film
PVA
TAC Film
TAC film
+TAC film
DLC layer
bbirubbing
편광판 제조 방식 (roll to roll)에 의해서 WV Film을 적용하는 TN의 경우 O mode 만이편광판 제조 방식 (roll to roll)에 의해서 WV Film을 적용하는 TN의 경우 O mode 만이적용되고 있다.
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Twist Nematic
Image Quality Comparison between TN and WVTN
3. Classification of LC Modes
Twisted Nematic : TN-. Twisted Nematic : TN-. Horizontal Switching : IPS, FFS
i l S i hi A A AS-. Vertical Switching : MVA, PVA, ASV-. π cell (OCB)
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
2. IPS Mode
Off OnLight
Substrate
Light Light
Transmittance ⎟⎠⎞
⎜⎝⎛ Δ
⋅=λλπα dnT )(sin)2(sin
21 22
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
2. IPS Mode
Ref. : S.T.Wu
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
White 상태 Color Shift 현상
1) 위치별 Color Shift.Y ll Shif
2. IPS Mode
R bbi White
Blue Shift Yellow Shift
⎟⎠⎞
⎜⎝⎛ Δ
⋅=λλπα dnT )(sin)2(sin
21 22
⇒시야각에 따라서Δn(λ)d가 변하기 때문에
2) Yellow Shift
Rubbing White
Fig . 러빙방향에따른 Color Shift 위치
⇒시야각에 따라서Δn(λ)d가 변하기 때문에최대 투과 파장이 달라지게 된다.
Δnd
Angleg
⇒Maximum 투과 point 장파장으로 shift:Yellow Shift
3) Blue Shift
Δnd
4) Color Shift Free
Δnd Angle
⇒ Single domain에서 dual domain으로변경시 color shift 현상 개선됨.
Angle⇒Maximum 투과 point 단파장으로 shift
:Blue Shift
변경시 color shift 현상 개선됨.
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
2. IPS Mode
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
3. FFS Mode
z
IPS FFS
y
z
Glass
Light Light
Glass
LightAnalyzer
x
y
Electric Field
LC Molecule
Glass GlassGlassPolarizer
Field
w l
l’Cst
S.H. Lee etal,Asia Display ‘98
IPS FFS
Light Lightp y
Appl. Phys. Lett. ‘98
IPS FFSl/dl/w
Fi ld
>1<1 or 0<1 or 0
E EE>1
Field
Electrodes
Ey, EzEy
ITOMetals or ITO
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
IPS-Pro (FFS) Structure by Hitachi3. FFS Mode
(Reference SID’99, S. H. Lee, et. al.) * Ono etal., IDW’04 & SID ’05
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
IPS FFS
3. FFS Mode
Transmissioncurve
LCLC
Field
IPS FFSDriving Field Ey (low field density) Ey & Ezg y ( y) y
(high field density)Switching Principle Dielectric Torque only Dielectric Torque + Elastic Torque
LC director in white state -Twist deformation only -Twist/tilt deformation y-Φ(l) ~ constant -Φ(l) ~ not constant
=> Self-compensation
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
-Need a compensation film?
Uncompensated IPS and FFS cell : better viewing angle than other modes owing to the in-plane rotation of the LC director
However, to accomplish a perfect dark state comparable to the CRT, , p p p ,they must be compensated by one or more films in the dark state.
<Iso-luminance contour of conventional HS mode in dark state>
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
Light Leakage of O-type Crossed Polarizers at oblique incidence
2 44 sin 2 sin1 o
l kT T φ θ=
( )( )2 2 2 28 1 cos sin 1 sin sinleakageo o
T Tφ θ φ θ− −
※ The factor “T” accounts for the Fresnel transmission of light through the four interfaces of the two polarizers
Maximum light leakagein diagonal direction (Φ=45˚)
60
80
0 010.020.030.040.05
LeakageT IPS exhibits relatively low C/R indiagonal direction.We consider about the improvementof diagonal direction (Φ=45˚)
020
4060
80 0
20
40
600
0.01
020
4060
80Viewing angleθ
φ
of diagonal direction (Φ 45 )
Fig . Calculated transmission of light passing through a pair of crossed ideal polarizers
Crossed O-type polarizer
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
Proposed S-IPS cell. (The combination of uniaxial and biaxial films)
TAC( C Pl )
Bi i l fil (N 0 5)TAC(-C Plate)
PVATAC(-C Plate)
+C PlateTAC(-C Plate)
PVATAC(-C Plate)
PVATAC(-C Plate)
TAC( C Plate)A Plate
Horizontal switching Cell
Biaxial film (Nz=0.5)
A Plate
Horizontal switching Cell
A Plate
TAC( C Plate)
Horizontal switching Cell
TAC(-C Plate)PVA
TAC(-C Plate)PVA
TAC(-C Plate)
Fig . structure #2TAC(-C Plate)
PVATAC(-C Plate)
Fig structure #1
TAC(-C Plate)PVA
TAC(-C Plate)
Fig . general structure gFig . structure #1
Ref : Jo n Ho Lee et al SID 05 p642
g g
Ref. : Joun-Ho Lee, et. al., SID 05, p642
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
▣ Comparison of the iso-contrast contour between general homogeneousS-IPS LC cell and proposed splayed S-IPS LC cell
Characteristics on viewing angle has been much more improved by applyingthe proposed S-IPS cell
DisplayDisplayDeviceDevice
LabLab3. LC Mode : Horizontal Switching
3. Classification of LC Modes
Twisted Nematic : TN-. Twisted Nematic : TN-. Horizontal Switching : IPS, FFS
i l S i hi A A AS-. Vertical Switching : MVA, PVA, ASV-. π cell (OCB)
DisplayDisplayDeviceDevice
LabLab4. LC Mode : Vertical Switching
- Dark: Control of light leakage in oblique direction by Film Compensation- White: How to tilt down LC directors in 4 or 8 directions: MVA, PVA, ASV, etc.
related to Transmittance Vop Response time Image quality
MVA PVA ASV
related to Transmittance, Vop, Response time, Image quality
MVA by Fujitsu
PVA by SEC
ASV by Sharp
Appearance 1997 1998 2001
Initial LC alignment Slightly tilt 90o Almost 90o
Method to tilt P t i ( d
Patterned ITO + down the LC:
Control of Field Direction
Protrusion (wedge shape) + Patterned
ITO
Patterned ITOs on both substrates
Protrusion (nipple shape)
LC director in white state
Bend deformation in Four directions
(ECB)
Bend deformation in Four directions
(ECB)
Twist/Bend/SplayDeformation(Reverse TN)( ) ( ) ( )
DisplayDisplayDeviceDevice
LabLab4. LC Mode : Vertical Switching
4. VA Mode
Black State Grey State White State
255grey109grey 199grey0 gray
DisplayDisplayDeviceDevice
LabLab4. LC Mode : Vertical Switching
4. VA Mode
◈ Conventional Type
◈ Improved Type
Side View Top View*Asia Display’97
p ypProtrusion in CF
Common electrode
Leakage near protrusions
Cross-sectional View Top View of Pixel
Electric Field Pixel electrode
DisplayDisplayDeviceDevice
LabLab4. LC Mode : Vertical Switching
On StateOn State Off StateOff State
4. VA Mode
On StateOn State Off StateOff State
MM
Protrusion
VVAA
Slit
PP
Slit
PPVVAA
SlitSlit
-. Color filter 층의 resin층 삭제로 Black 특성은 MVA 대비 PVA 우수
반면 PVA의 경우 Black to White transition 응답특성에 문제 발생-. 반면 PVA의 경우 Black to White transition 응답특성에 문제 발생
새로운 구동법 개발을 통해서 개선 (DCC2)
DisplayDisplayDeviceDevice
LabLab4. LC Mode : Vertical Switching
4. VA Mode
Gamma shift
VAIPS
VA
VA Mode 구동 특성상 측면 시야각에서 gamma shift 현상 발생8 d i 구동 기술 도입: 8 domain 구동 기술 도입
DisplayDisplayDeviceDevice
LabLab4. LC Mode : Vertical Switching
4. VA Mode
:4 domain 8 domain
*IMID ’04
DisplayDisplayDeviceDevice
LabLab4. LC Mode : Vertical Switching
4. VA Mode
*S.S. Kim, SID ‘05
3. Classification of LC Modes
Twisted Nematic : TN-. Twisted Nematic : TN-. Horizontal Switching : IPS, FFS
i l S i hi A A AS-. Vertical Switching : MVA, PVA, ASV-. π cell (OCB)
DisplayDisplayDeviceDevice
LabLab5. LC Mode : π - cell
5. π - cell
2축성 보상필름
편광판 Rubbing direction
V < Vth Vth < V
밴드 셀
( Bend Cell )
편광판
splay cell bend cell(off) bend cell(on)
DisplayDisplayDeviceDevice
LabLab5. LC Mode : π - cell
(1) T-V curve
S l
5. π - cell
100
BendSplay
60
80
tace
40
Tra
nsm
it
0
20
0 1 2 3 4 5 6 7 8 9 100 1 2 3 4 5 6 7 8 9 10
Applied Voltage(V)
S l t B d h 전이과정이 필요(최소 1V 이상)Splay to Bend phase 전이과정이 필요(최소 1V 이상)
DisplayDisplayDeviceDevice
LabLab5. LC Mode : π - cell
Fast response is possible as flow of the same direction appears in bend cell.
5. π - cell
flow
flowflow
Bend cellBend cell
Von VoffTN cellTN cell
Von Voff
When door are moved to the opposite di i i b i fl i
When force is applied to the same direction the door can be openeddirection, resistance by air flow increases. direction, the door can be opened more easily as there is little resistance due to air.
DisplayDisplayDeviceDevice
LabLab5. LC Mode : π - cell
5. π - cell
Voltage OFF~
Voltage OFF(Splay)
~Lower Voltage(Bend)
P.J. Bos et el SID Digest p273 (1993)Higher Voltage(Bend)~
DisplayDisplayDeviceDevice
LabLab5. LC Mode : π - cell
5. π - cell
Ref IDW’04
Major technologies used:
LTPS + High Aperture + CF on array + Ref. IDW’04, Toshiba Matsushita Display Technology. Co.,Ltd.Impulse driving method