1/21 Flat Panel Display System Lab. C.L. Wu Speaker: Chi-Lin Wu ( 吳其霖 ) Advisor: Prof. Han-Ping D. Shieh Department of Photonics and Display Institute, National Chiao Tung University, Hsinchu, Taiwan April 14th 2007 Prof. Yi-Pai Huang High Transmittance LC Pixel Design for Multi- View 3D Mobile Display 高穿透效率之立體顯示器液晶畫素設計 高穿透效率之立體顯示器液晶畫素設計

2/21 Flat Panel Display System Lab. C.L. Wu Outline  Introduction - 3D Displays - Motivation & Objective  Pixel Design - LC Cell (single domain) - Aperture Ratio of Array - Aperture Ratio of Barrier  Measurement Results  Conclusions & Future Works

3/21 Flat Panel Display System Lab. C.L. Wu Introduction Left Eye Right Eye 3D Displays: 1. Binocular parallax 2. Motion parallax 3D Displays: 1. Binocular parallax 2. Motion parallax Real World:

4/21 Flat Panel Display System Lab. C.L. Wu 2 views Multi views Narrow viewing zone L eye R eye Barrier view 1view 2 LCD Advantage Advantage Wider viewing zone (more natural 3D) Disadvantage Disadvantage Lower brightness Advantage Advantage Wider viewing zone (more natural 3D) Disadvantage Disadvantage Lower brightness Unbalanced brightness Motivation viewing angle T View 3 Conventional Pixel viewing angle T View 1 Barrier pixel3 pixel1

5/21 Flat Panel Display System Lab. C.L. Wu Objective Barrier (NTHU) Array LC cell Backlight LCD Slanted barrier 3D display BumpNo Bump, Cst shape 3 Factors 1.LC cell 2.Array 3.Barrier 3 Factors 1.LC cell 2.Array 3.Barrier Aperture Ratio MultiSingle Objective: 1.6-view slant barrier 3D display 2.Brightness improvement~20%Objective: 1.6-view slant barrier 3D display 2.Brightness improvement~20%

6/21 Flat Panel Display System Lab. C.L. Wu Outline  Introduction - 3D Displays - Motivation& Objective  Pixel Design - LC Cell (single domain) - Aperture Ratio of Array - Aperture Ratio of Barrier  Measurement Results  Conclusions & Future Works

7/21 Flat Panel Display System Lab. C.L. Wu -2˚2˚6˚9˚-6˚-9˚ Barrier LCD proposed (pixel 1) 711 viewing angle T Barrier Transmittance (a.u.) Viewing angle(°) Conventional view points Novel 3D 6-view points Design of LC Cell Advantage 1. Higher brightness at the wider viewing points 2. Balanced brightness at the 6-viewing points Two methods based on single domain VA Advantage 1. Higher brightness at the wider viewing points 2. Balanced brightness at the 6-viewing points Two methods based on single domain VA

8/21 Flat Panel Display System Lab. C.L. Wu Why Single-Domain VA? Single domain Multi-domain 2D DisplayProposed Display LC alignment T (a.u.) θ(°) Single domain 1.Single domain VA is used for design. 2.Two methods of single domain LC (1) Different thickness of C Plate Single Domain (2)Normally White Single Domain Single domain 1.Single domain VA is used for design. 2.Two methods of single domain LC (1) Different thickness of C Plate Single Domain (2)Normally White Single Domain Wide Viewing AngleNarrow Viewing Angle Brighter at Specific Angle

9/21 Flat Panel Display System Lab. C.L. Wu : viewing angle : total thickness of C plates : phase retardation of LC : birefringence of C plate : twist angle (LC v.s. polarizer) Absorption axis Polarizer λ /4 plate Negative c plate MVA-b Conventional 2.83 MVA-b LC Cell-thickness of C plate Single domain VA nono nono nene θ Total phase retardation Transmittance Certain Voltage θ d2 d1> d T (a.u.) θ(°) Single domain VA T max d1 < 0 LC -C plate θAθA θBθB The maximum transmittance can be shift to a specific viewing angle by changing thickness of C plate The maximum transmittance can be shift to a specific viewing angle by changing thickness of C plate

10/21 Flat Panel Display System Lab. C.L. Wu Simulation-thickness of C plate Polarizer Absorption axis Polarizer λ /4 plate Negative c plate Single domain VA y z Φ x d1 d2 1.The maximum transmittance can be generated at a specific viewing angle by changing thickness of C plate. 2. Drawback: Difficult to fabricate 1.The maximum transmittance can be generated at a specific viewing angle by changing thickness of C plate. 2. Drawback: Difficult to fabricate Conventional (Bright state) Single Domain (Bright state) Single Domain (Gray level state)

11/21 Flat Panel Display System Lab. C.L. Wu (c) View 4 (-2°)(d) View 3 (2°)(e) View 2 (6°)(f) View 1 (9°)(a) View 6 (-9°)(b) View 5 (-6°) -9° -6° -2° 2° 6° 9° Conventional (Bright state) Single Domain (Bright state) Single Domain (Gray level state) Normally White Single Domain VA Absorption axis Polarizer λ /4 plate Negative c plate Single domain VA y z Φ x Φ The maximum transmittance can be generated at a specific viewing angle by Normally white single domain.

12/21 Flat Panel Display System Lab. C.L. Wu Normally White Single Domain VA Transmittance(a.u.) Viewing angle(deg.) 6-view slanted barrier Conventional (Bright state) Single Domain (Bright state) Normally white single domain VA: 1.Transmittance: View 6~7% 2.Balanced brightness 3.Driving Control: Same Normally white single domain VA: 1.Transmittance: View 6~7% 2.Balanced brightness 3.Driving Control: Same Voltage (Volt.) Transmittance (a.u.) V-T curve

13/21 Flat Panel Display System Lab. C.L. Wu Aperture Ratio of Pixel 30um X 90um CF TFT Fringe field Bump ITO Metal (block light leakage) Conventional A.R.=52%A.R.=45% ~16% Single-domain VA (Bump) (no bump) Conventional Proposed

14/21 Flat Panel Display System Lab. C.L. Wu Aperture Ratio of Barrier Cst View 5 View 6 θ a b Luminance Crosstalk=b/a Conventional Proposed Cst Shape of storage capacitance Aperture ratio of barrier (NTHU) 8.9%14.3% ~60% (Under 5%crosstalk) (1) Total brightness (2) Cross-talk (1) Total brightness (2) Cross-talk

15/21 Flat Panel Display System Lab. C.L. Wu Φ Summary x φ Barrier Array LC cell Backlight LCD ~7% ~16% ~60% Total Improvement~98% (5%crosstalk)

16/21 Flat Panel Display System Lab. C.L. Wu Discussion 2D/3D switchable display(same resolution for 2D and 3D) EE can not support for increasing resolution. Fabrication: Multi-domain VA 3D Image(single domain) 3D Image D Image(multi-domain) Poor resolution for 2D image

17/21 Flat Panel Display System Lab. C.L. Wu Outline  Introduction - 3D Displays - Motivation& Objective  Pixel Design - LC Cell (single domain) - Aperture Ratio of Array - Aperture Ratio of Barrier  Measurement Results  Conclusions & Future Works

18/21 Flat Panel Display System Lab. C.L. Wu Measurement Result Conventional 6-view 3D display(2.4”) Proposed pixel is fabricated by AUO.

19/21 Flat Panel Display System Lab. C.L. Wu Outline  Introduction - 3D Displays - Motivation& Objective  Pixel Design - LC Cell (single domain) - Aperture Ratio of Array - Aperture Ratio of Barrier  Measurement Results  Conclusions & Future Works

20/21 Flat Panel Display System Lab. C.L. Wu Conclusion The transmittance ratio of Normally White Single Domain method enhance~24% for view 6(~9°) - Transmittance of LC enhance~ 7% - Aperture ratio of Array increase ~16% The total improvement~98% (5% crosstalk) Barrier Array LC cell Backlight LCD ~7% ~16% ~60%

21/21 Flat Panel Display System Lab. C.L. Wu Future Works Short term –Measure the brightness of proposed pixel Without parallax barrier With parallax barrier –Analyze the measurement results Compare with the simulation results Long term –Increase the resolution

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23/21 Flat Panel Display System Lab. C.L. Wu How to divide LC domains? Robbing Method –Demerit: Complex process Limitation on the number of domains (max=2) Hard to precisely control ADF (Automatic Domain Formation) –Merit: Easy to create Little damage Alignment uniformity can be predicted before filling with the LC material Therefore, LC domains are divided by using ADF technology

24/21 Flat Panel Display System Lab. C.L. Wu PSA V UV V ITO PI Monomer Polymer layer Polymer Sustained Alignment K. Hanaoka et al., Digest of SID04, p1200(2004)

25/21 Flat Panel Display System Lab. C.L. Wu Advantages of PSA-LCD Conventional MVA 1.less brightness (effective aperture ratio  ) 2.CR(~500:1) 3.slow response 4.alignment disorder PSA-LCD 1.Aperture ratio  2.Higher CR 3.Fast response 4.No disorder alignment problem

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27/21 Flat Panel Display System Lab. C.L. Wu Negative C plate LC Γ: Phase Retardation θ: Viewing Angle θ Dark State - C plate

28/21 Flat Panel Display System Lab. C.L. Wu Aperture ratio can be increased by optimizing TFT position for the slant barrier. TFT Transmission area of slant barrier Slant barrier Slant barrier for 4-viewng points