Session 9.1 SID2010 May 25 th, Sep Lyu Jae Jin. Samsung Electronics

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1 Session 9.1 SID2010 May 25 th, 2010 Sep Lyu Jae Jin Samsung Electronics

2 Contents 2

3 Application of LCDs Projection Type: LCD Projector, Projection TV Direct View Type: Smart-Phone, I-Pad, N-PC, Monitor, TV Reflective Type: PDA, Cellular Phone, Digital-Camera Trans-Reflective Type : PDA, I-Pod 3

Scanning Electrodes Scanning Electrodes Driving Method of LCDs * TFT : Thin Film Transistor Signal Electrodes Signal Electrodes Segment Passive Matrix

4 Scanning Electrodes Scanning Electrodes Driving Method of LCDs * TFT : Thin Film Transistor Signal Electrodes Signal Electrodes Segment Passive Matrix Active Matrix Use of TFT!! Simple Fab.; Low resolution Simple Fab.; Limited resolution Limited Quality Complicated Fab.; High resolution High Quality 4

5 Structure of TFT-LCD Many electronic and optical components with organic and organic materials are used! Having supplying industries for components are important to lead in a competition!! 5

6 Structure of Color TFT Panel 6

7 Photolithography Process PR : photoresist 7

8 TFT-Array Fabrication Process 8

9 ADDRESSING OF TFT-Array 9/65

10 Color Filter Fabrication Process 10

11 LC Fabrication Process ODF Assembly Conventional Filling 11

12 Structure of Driving Circuit Unit 12

13 Structure of BL Unit 13

14 What needs to be improved in LCDs? <Comparison of LCD TV with CRT and PDP> Performance LCD PDP CRT Weight/Thickness Excellent Good Fair Resolution Excellent Good Poor Full Brightness Excellent Fair Fair Peak Brightness Good Good Excellent Contrast Ratio in the Bright Room Excellent Good Good Contrast Ratio in the Dark Room Good Good Excellent Moving Picture Response Fair/Good Good Excellent Viewing Angle Good Excellent Excellent Power Consumption Good Poor Fair PDP : Plasma Display Panel, CRT : Cathode Ray Tube *source: Hitachi 14

15 Moving Picture Quality Issue LC: Viscous liquid Reorientation by dielectric torque or Black data insertion or Frame rate change Hz 120 Hz 240 Hz

16 Issue on Viewing Angle & CR Problem 1 LC: Anisotropic structure (Δn, Δε) Problem 2 Polarizer: Incomplete control of light => Light leakage exists!! P A Viewing Angle Dependence: Intrinsic Problem in LCD 16

17 Wide Viewing Angle LC Modes Modes Initial Align. Field Direction Application Fields HA Homogeneous -IPS Alignment (HA) -In-plane (Ey) -Monitors, LC-TVs, Medicals -FFS -Fringe (Ey & Ez) -All small size LCDs, Tablet PCs, Notebooks, Monitors, LC-TVs, Medicals VA -MVA Vertical Alignment (VA) -Vertical (Ez) -Monitors & LC-TVs -PVA -Oblique (Ey & Ez) -Monitors & LC-TVs -ASV -Fringe (Ex,y & Ez) -Mobile Phones & LC-TVs OCB (π-cell) Splay -Vertical (Ez) -LC-TV -IPS: In-Plane Switching -FFS: Fringe-Field Switching -MVA: Multi-domain vertical alignment; -PVA: Patterned Vertical Alignment; ASV: Advanced Super-View -OCB: Optically Compensated Bend 17

18 Homogenous Alignment: IPS vs. FFS 18

19 In-Plane Switching (IPS) Mode Off Light On Transmittance Eqn.: T=T o sin 2 2Φsin 2 (πdδn/λ) Substrate Light Light Dark State : V = 0, Φ = 0 o ; Lin. Pol. LC Lin. Pol. Light is blocked by Analyzer Bright State: V > Vth, Φ(V): 0 o 45 o ; Lin. Pol. LC Rotated ( 0 90 o ) Light appears Dark State : dδn (Θ,Φ) at off normal is very small Light Leakage is Minimized Bright State: variation of dδn (Θ,Φ) at fixed Θ is small Good Brightness Uniformity Wide viewing angle but low transmittance 19

20 Color Characteristics : 1D vs. 2D <1D- IPS> <2D- IPS> White state 20

Fringe-Field Switching (FFS) Mode w IPS Light Light Glass l Glass Light Analyzer LC Molecule Electric Field Polarizer l FF S Light Glass Glass Light x z C st y S.H.

21 Fringe-Field Switching (FFS) Mode w IPS Light Light Glass l Glass Light Analyzer LC Molecule Electric Field Polarizer l FF S Light Glass Glass Light x z C st y S.H. Lee etal, Asia Display 98 Appl. Phys. Lett. 98 IPS FFS l/d l/w Field >1 >1 Ey <1 or 0 <1 or 0 Ey, Ez FFS: Wide Viewing Angle/ High Transmittance Electrodes Metals or ITO ITO 21

22 IPS-Pro (FFS) Structure by Hitachi (Reference SID 99, S. H. Lee, et. al.) * Ono etal., IDW 04 & SID 05 22

23 Vertical Alignment: MVA vs. PVA vs. ASV 23

24 Key Issues in VA Modes - 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 by Fujitsu PVA by SEC ASV by Sharp Appearance Initial LC alignment Slightly tilt 90 o Almost 90 o Method to tilt down the LC: Control of Field Direction Protrusion (wedge shape) + Patterned ITO Patterned ITOs on both substrates Patterned ITO + Protrusion (nipple shape) LC director in white state Bend deformation in Four directions (Phase retardation) Bend deformation in Four directions (Phase retardation) Twist/Bend/Splay Deformation (Polarization Rot.) 24

Dark State : dδn (Θ,Φ) of LC cell is very small by Film Compensation Bright State: dδn (Φ) at

25 Multi-Domain : symmetric Luminance -Fujitsu(MVA), Sharp (ASV), SEC (PVA) Transmittance: T=T o sin 2 2Φsin 2 (πdδn/λ) Off Light Light On P A Substrate < 4-Domain VA: On state> Light Light Dark State : dδn (Θ,Φ) of LC cell is very small by Film Compensation Bright State: dδn (Φ) at fixed Θ is constant Excellent Brightness Uniformity Wide Viewing Angle and HighTransmittance 25

26 Color Washout Issue -Reason: Effective dδn change with Θ & Φ Solution: 4 domain 8 domain 26

27 4Doamin 8Domain structure -8 Domain: Control of two sub pixels by Two transistors *S.S. Kim (Samsung), SID 05 27

28 What is Green Technology in LCD? Green Device Green Process Green Factory Energy Efficient Device Free from Hazardous materials Energy Efficient Manufacturing Direct Printing Process Energy Saving Process Environment Friendly Process CO2 reduction Recycle CF Inkjet Printing High Efficient BLU Pattern Printing 28

29 What is Green LCD? Use of Energy Efficient Technologies consuming less power Use of Environment Friendly Components & Materials Compliance with Environment Regulations (i.e., recycle) 29

30 Overview : Green Process Reduced Process Step TFT Process 5M 4M 3M Photo less Reduced Energy process Low Temp. process Reduced Materials Green Process requires many Breakthrough Technologies 30

used etchant - used sputter target - used organic materials - used/broken glass - Water

31 Green Factory Reduction of Greenhouse Gases (CO2, SF6, PFC etc.) - Electrical power saving - use less material No hazardous material & component FACTORY - used etchant - used sputter target - used organic materials - used/broken glass - Water purification - Organic drain recycle - Bio-plastic - Small volume Customers Reuse / Recycle Company - Waste reduction End-of life Product 31

32 Summary : Green Technology in LCD Device Low power consumption Slim, Light, Narrow Process Simple process Energy & material saving process Factory Saving of water & Electricity Recycle & Waste reduction 32

33 Summary 1. Carbon Footprint point of view, making Energy Efficient Device has the most significant impact. 2. Green Technology is not only good for the earth, but also it gives money savings. 3. Green Device + Green Process + Green Factory; When they work together, they can create a practical value getting closer to the customers. 33

34 Thank You 34

Viewing angle control mode using nematic bistability

Viewing angle control mode using nematic bistability Jin Seog Gwag 1, You-Jin Lee 2, Myung-Eun Kim 2, Jae-Hoon Kim 1,2,3*, Jae Chang Kim 4, and Tae-Hoon Yoon 4 1 Research Institute of Information Display,