Flat Panel Displays: 1. Introduction

OSE-6820 Flat Panel Displays: 1. Introduction Prof. Shin-Tson Wu College of Optics & Photonics University of Central Florida Email: swu@mail.ucf.edu Office: CREOL 280 Phone: 407-823-4763 UCF College of Optics & Photonics CREOL & FPCE Photonics & Display Group 1

Tentative Class Schedules 05/19: Introduction 05/21: LC materials 05/26: LCD I 05/28: LCD II 06/02: Lab I 06/04: Lab II 06/09: TR-LCD I 06/11: TR-LCD II 06/16: TFT I 06/18: TFT II 06/23: Special topic 06/30: Midterm 07/02: Special topic 07/07: Projection 07/09: e-paper 07/14: LED I 07/16: LED II 07/21: OLED I 07/23: OLED II 07/28: PDP 07/30: FED 08/04: Final 08/06: Final 2

Grading Policy Homework: 30% Midterm: 30% Final: 40% Reference: JH Lee, DN Liu, and ST Wu, Introduction to Flat Panel Displays (Wiley, 2008) 3

Main Objectives Training for Ph.D. students: 1. Create new knowledge 2. Disseminate results (written) 3. Communicate results (oral) 4. Defend your thoughts 5. Team approach 4

Team Assignment Very diversified background!! 5

Midterm: Team Debate If you were a company CEO: 1. Should you produce wide view NB computers? Team 1: Yes, & Team 2: No. 2. Which wide view LCD TV technology should you focus? Team 3: IPS, & Team 4: MVA. 3. Should you develop transflective or transmissive LCDs for cell phones/pdas? Team 5: TR LCD, & Team 6: T LCD. 4. LED BLU is the technology trend for NB and TVs. Should you go for white LED or RGB LED approaches? Team 7: White LED, & Team 8: RGB. 6

Final Presentations: 8/4 & 8/6 1. What is your favorite FPD technology? Justify. Each student will have 15 20 minutes to present All students will score you based on the 5 presentation principles My score only counts for 50%. 5 presentation principles: 1. Impressive, 2. Exciting, 3. Entertaining 4. Informative, 5. Persuasive 7

Society Awards Society award criteria 1. Research excellence 2. Presentation prowess 3. Leadership 4. Recommendation IEEE/LEOS fellowship: 12 top students OSA NFB award: Top 7 students SPIE: Very generous 8

Research Excellence 1. Select good research topics 2. Publish a few good papers 3. Quality vs. quantity 4. Book chapter? 5. Presentations: invited talks 9

Presentation Prowess 1. Practice makes perfect 2. Attend 4-5 conferences and present papers before you graduate 3. Invited talks carry more weight 5 presentation principles: 1. Impressive, 2. Exciting, 3. Entertaining 4. Informative, 5. Persuasive 10

Leadership 1 st year: High GPA, Pass qualify; Join societies (LEOS, OSA, SPIE, SID etc) as a student member 2 nd year: Serve as a student officer; Interact with eminent scholars; Publish 1-2 papers 3 rd year: Take leadership; Apply for SPIE scholarship; Publish few more papers; Attend conferences 4 th year: Compete for all awards 11

Nomination/Recommendation 1. Select an eminent advisor who cares for your future success. 2. Let your advisor know you more than just your work! 3. Select your committee members 4. If you are really good, ask for nomination!! Reputation takes time to build up. 5. Do not be depressed if you are not nominated. Everyone has different talents. Be self confident! 12

Co-authorship 1. Encourage collaborations 2. Give proper credit to your collaborators 3. Train your management skills 4. Big difference between 1 st author and co-authors 5. 1 st author gets major credit 13

TV Market Forecast DisplaySearch: : Q4, 2008 2009: LCD/PDP/CRT~73/15/12 14

Major FPD Technologies A. Emissive Displays 1. Plasma Display Panel (PDP) 2. Light Emitting Diode (LED) 3. Organic Light Emitting Display (OLED) 4. Field Emission Display (FED) B. Non-emissive Displays 1. Liquid crystal display 2. Electrophoretic Display (EPD) 3. Interferometric Modulation (imod) C. Projection Displays 1. Transmissive/reflective LCDs 2. Digital Light Processing (DLP) 3. Grating Light Valve 15

Plasma Display Panel (PDP) Gas discharge UV Phosphors RGB lights 16

Light Emitting Diode (LED) Forward biased PN Junction RGB LEDs PN junction Electron Hole Recombination Light emission Wide applications: Displays and Lighting 17

Organic Light Emitting Diode (OLED) Schematic of a 2 layer OLED: 1. Cathode ( ), 2. Emissive Layer, 3. Emission of radiation, 4. Conductive Layer, 5. Anode (+) 18

Field Emission Display (FED) Emitters Accelerated electrons bombard phosphors Light emission (Flat CRT) 19

Transmissive TFT-LCD Gate or row electrode Common electrode Color filter a-si TFTs ITO TFT substrate Polarizer 240 µm Backlight Diffuser 80 µm Data or column electrode Gate or row electrode LC Polarizer Common substrate Each pixel is independently driven by a TFT 21

Electrophoretic Display (EPD) Positively charged white pigments and negatively charged black pigments in dielectric clear fluid are moved by applied electric field. E reader B/W + color filters 22

Interferometric Modulation (imod) 23

Major FPD Technologies A. Emissive Displays 1. Plasma Display Panel (PDP) 2. Light Emitting Diode (LED) 3. Organic Light Emitting Display (OLED) 4. Field Emission Display (FED) B. Non-emissive Displays 1. Liquid crystal display 2. Electro-Phoretic Display (EPD) 3. Interferometric Modulation (imod) C. Projection Displays 1. Transmissive/reflective LCDs 2. Digital Light Processing (DLP) 3. Grating Light Valve 24

Transmissive/Reflective LCD Projectors Transmissive Reflective White Light P A Color Recombiner To Screen Projection Lens R-LCD Philips Prism TIR Surfaces PBS 3 LCD panels for RGB 25

TI DLP Projection Displays Digital Micromirror Device: Polarization independent 26

Pico Projector Besides conventional front/rear projectors, pico projector is cool! http://www.youtube.com/watch?v=7ufarrm0bom 27

Grating Light Valve (1) 28

Grating Light Valve (2) 29

Rear Projection TVs Optical engine is behind screen 30

Cathode Ray Tube (CRT) Brightness: High (shadow mask CRT) to very high (PTV-CRT) Contrast: Dark ambient: Excellent Bright ambient: Poor (Reflection: shadow mask) Resolution: Medium to high Long Life: >30,000 hours Low Cost: <$10/inch Bulky & heavy 31

Monochrome CRT phosphor layer Vacuum makes electrons easy to handle 32

Shadow Mask CRT shadow mask 3 electron beams s phosphor pattern 33

Shadow Mask CRT and Beam Landing 34

Braun s s CRT: 1897 35

In-line Electron Gun G 1 G 2 G 3 G 4 G 1 G 2 G 3 G 4 G 1 G 2 G 3 G 4 Guns are tilted for convergence Integrated gun 36

Principle of CRT Electron Gun triode G1 cathode G2 G3 G4 electron beam cathode lens prefocussing lens beam crossover main lens 37

Principle of Deflecting e-beame tube neck upper half line coil gun e- B F v deflection current lower half line coil 38

Electron Beam Deflection (1) A static charge q in an electric field E Electric Force F E = qe =ma (2) A moving charge q in a magnetic field B Magnetic force F M = q v B (3) If q is moving through a region pervaded by both E and B, forces F E and F M on q occur concurrently. F= qe + q v B Mass spectrometer 39

Deflection Coils toroidal saddle mussel 40

Interlaced Scanning 1 2 3 4 5 6 7 8 9 41

SEM picture of shadow mask for CRT View from screen side 42

Mask and Screen Structures a h a v a h MASK a dot a v Slots Slits or Aperture Grill a h Hexagonal Phosphor in Black Matrix Phosphor Triad or Triplet Phosphor Triad or Triplet 43

Doubly curved shadow mask for 32 16:9 CPT Diaphragm 44

Principle of Beam Landing 45

Phosphor pattern & matrix in CRT Front view Electron spot size matrix Panel Cross section 46

Phosphor layer and matrix window Electron beam Secondary electrons Aluminum mirror Phosphor grains Front Glass Light out 47

Spectral Emission of CRT P22 Phosphors Red: Y2O2S:Eu+Fe2O3; Green: ZnS:Cu,Al ; Blue: ZnS:Ag+Co on Al2O3 48

Color Gamut of CRT (MNT) Typical color gamut: ~72% NTSC 49

CRT Projection 51

CRT Era Is Ending Soon 1. EM radiation: Keep a proper viewing distance >85 cm 2. Ionizing Radiation Could generate X ray after e beam bombardment of the shadow mask & phosphors 3. Toxicity: CRTs may contain toxic phosphors within the glass envelope. The glass envelopes of modern CRTs may be made from heavily leaded glass, which represent an environmental hazard. 4. Flicker: 60 80 Hz 5. High Voltage Vacuum Tube 6. High power consumption 52