Presentation is loading. Please wait.

Presentation is loading. Please wait.

Universität Dortmund Seminar Moderne Displaytechnik Electroluminescence Displays Fakultät für Elektrotechnik und Informationstechnik Lehrstuhl für Kommunikationstechnik.

Similar presentations


Presentation on theme: "Universität Dortmund Seminar Moderne Displaytechnik Electroluminescence Displays Fakultät für Elektrotechnik und Informationstechnik Lehrstuhl für Kommunikationstechnik."— Presentation transcript:

1 Universität Dortmund Seminar Moderne Displaytechnik Electroluminescence Displays Fakultät für Elektrotechnik und Informationstechnik Lehrstuhl für Kommunikationstechnik Prof. Dr.-Ing. Rüdiger Kays Jens Bömer jcbsystems@gmx.de

2 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 2 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Table of Contents 8Introduction 8Principles of Electroluminescence (EL) 8general effect 8high-field EL 8Technological Realization 8layer structure 8Selected Approaches to 8produce colours 8make a display 8Applications/ Products 8Pros & Cons Electroluminescence: Basics & Technology

3 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 3 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Introduction tendency to miniaturizement fast response for video services low power consumption Motivating Forces

4 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 4 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Introduction phosphorus material hot-electrons impact excitation ElectroluminescenceHigh Field EL LED & OLED non-thermal conversion of electrical energy into light pn-junction electron-hole pair recombination

5 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 5 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Principles of EL electrical energy is converted into light energy operation at low temperatures possible Requirements band gap (E g ) higher than 3.0eV special semiconductor insulator Luminescence Fluorescence t 1 s Phosphorescence t 1min -... E E0E0 E1E1 E2E2 EgEg

6 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 6 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Principles of EL e-e- excited state impurity ground state top insulator bottom insulator Al ITO... insulator/ phosphor interface states electrons tunnel into phosphor electrons accelerated by electric field (high energy or hot electrons > 2 eV) Electron transport Excitation collisions with lattice/ ímpurity atoms (e.g. Mn) luminescent impurity absorbs electrons energy excited impurity relaxes by emitting a photon High Field EL

7 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 7 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Technological Realization insulator/phosphor/insulator stack insulators limit short current electric field strength > 1.5 MV/cm 165 V alternating voltage thin film EL (TFEL) AC electrode insulator ( 250nm) phosphor ( 600nm) wide viewing angle luminosity controlled by pulse width modulation T

8 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 8 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Colourful Materials Red ZnS:Mn organic red filter Green ZnS:TbOF SrS:Ce Amber ZnS:Mn Blue SrS:Ce SrS:Cu,Ag White stacked layers SrS:Ce and ZnS:Mn rare earth oxids and oxysulfats (as in CRT)

9 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 9 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Facts Concerning Colours Efficiency red: 0.8 lm/W green: 1.0 lm/W blue: 0.2 lm/W Luminance (max.) red: 70 cd/m 2 green 160 cd/m 2 blue: 100 cd/m 2 white: 470 cd/m 2 operating temperature -30° C to 65°C

10 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 10 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Comparison of EL and LCD 18:1-150:1 200 cd/m 2 100° (recently up to 170°) 20W 150:1 150 cd/m 2 > 160° 3W LCD: thin film EL Contrast ratio Luminance Viewing angle Power consumption

11 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 11 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Selected Approach to Produce Colors One approach: Colour by White indium-tin oxide (ITO) top electrode pixel size of 12 or 24 micron broad band white phosphor patterned colour filter simple device fabrication low-cost production

12 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 12 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Selected Approach to Make a Display Active Matrix (AMEL) Display Organization line drivers column drivers Technological advantages EL pixel ITO data line high integration level low capacity less current reduction of control wires fast response

13 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 13 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Selected Approach to Make a Display aging characteristics of the phosphor inverted structure brightness controlled by pulse width modulation high resolution (2000 lpi) reduced power consumption higher brightness expanded grayscal capability Silicon On Insulator (SOI): Required isolation between high voltage AC of EL device and low voltage digital signals which address each pixel. Advantages of AMELTechnological features t b

14 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 14 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Applications What is ACTFEL? ACTFEL: alternating current thin film electroluminescence used in cars high reliability wide temperature range luminance: red: 23 cd/m 2 amber: 140 cd/m 2 green: 25 cd/m 2 transparent minimize drivers eye movement visibility under sunlight pixel luminance: amber: 1200 cd/m 2 green: 500 cd/m 2 head-up displays (HUD)instrument panels

15 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 15 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Products car control panel (ACTFEL) Products camcorder head mounted display EL foil EL display

16 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 16 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Pros and Cons high resolution fast response low power consumption wide viewing angle ruggedness low-cost production use at low temperatures visibility under sunlight inadequate brightness and chromaticity aging characteristics high voltage alternating current PROCONTRA

17 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 17 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Summary 8HFEL bases on high energy electrons (hot electrons) 8Self-emitting technology instead of light through (LCD) 8Realization with an insulator/phosphor/insulator stack 8Multi-colour displays by white phosphor and colour filters 8Various monochrome control panels by variation of dopants 8Active matrix integration (AMEL) 8Application in cars, laptops, head-mounted-displays, camcorder

18 Seminar Moderne Displaytechnik 8. Februar 2002 Folie 18 Lehrstuhl für Kommunikationstechnik Prof. Dr. Rüdiger Kays Technological Realization U [V] Q [C] Q = C U V1V1 V th V3V3 dissipated energy charge stored at interface lowers the diode current remaining charge lowers turn-on voltage CICI CICI CPCP USUS C I : insulators capacity C P : phosphors capactiy


Download ppt "Universität Dortmund Seminar Moderne Displaytechnik Electroluminescence Displays Fakultät für Elektrotechnik und Informationstechnik Lehrstuhl für Kommunikationstechnik."

Similar presentations


Ads by Google