1. Electrophoretic Display Power and Mobile Computing Devices Michael A. Baker March 4, 2007 CSE 591 Low Power Computer Architecture Instructor: Aviral Shrivastava

2. 2 Agenda Introduction Mobile computing device displays Electrophoretic displays LCD power management schemes Power modeling References Timeline

3. 3 Mobile Computing Device Display Technologies Non-EmissiveEmissive OLED (Organic Light Emitting Diode) SRD (Scanning Retinal Displays) PLED (Polymer based OLED) SMOLED (Polymer based OLED) Electrophoretic LCD (Liquid Crystal Display) Active MatrixPassive Matrix IMOD (Inferometric Modulator)

4. 4 Display Technology © 2007 QUALCOMM MEMS Technologies, Inc. LCD Electrophoretic DisplaysOLED LCD

5. 5 Electrophoretic Display Process © 2007 QUALCOMM MEMS Technologies, Inc.

6. 6 LCD power management schemes/ applicability to EPDs Concurrent Brightness and Contrast Scaling (CBCS) Graphical User Interface optimization Variable Dot Clock Scaling Variable Frame Refresh Multiplexed driver optimization

7. 7 EPD and LCD Modeling TFT pixel equivalent circuit from Low Power Control Techniques For TFT LCD Displays, 2002 EPD addressing scheme from An Electrophoretic Display, Its Properties, Model, and Addressing, 1979

8. 8 Calculating LCD Power Consumption Representation of display driver and LCD pixels

9. 9 Power Calculation for Multiplexed LCD Equations from [6] enabling power estimation for a multiplexed display with pixels modeled as capacitors Power given is for the display drawn once

10. 10 Primary References [1] Pedram, Cheng, Hou, Power Minimization in a Backlit TFT-LCD Display by Concurrent Brightness and Contrast Scaling, 2004Pedram, Cheng, Hou, Power Minimization in a Backlit TFT-LCD Display by Concurrent Brightness and Contrast Scaling, 2004 [2] Herz, Electrophoretic Display technology: The beginnings, the improvements, and a future in flexible electronics, May 19, 2006Herz, Electrophoretic Display technology: The beginnings, the improvements, and a future in flexible electronics, May 19, 2006 [3] Zhong, Jha, Graphical User Interface Energy Characterization for Handheld Computers, October 2003Zhong, Jha, Graphical User Interface Energy Characterization for Handheld Computers, October 2003 [4] Dalisa, Electrophoretic Display Technology, 1977Dalisa, Electrophoretic Display Technology, 1977 [5] Gatti, Acquaviva, Benini, Ricco’, Low Power Control Techniques For TFT LCD Displays, 2002Gatti, Acquaviva, Benini, Ricco’, Low Power Control Techniques For TFT LCD Displays, 2002 [6] Marks, Power Consumption in Multiplexed Liquid-Crystal Displays, 1982Marks, Power Consumption in Multiplexed Liquid-Crystal Displays, 1982

11. 11 Timeline 9 Mar: Develop model fundamentals for LCD and EPD power consumption 30 Mar: Implement model (DEVSJAVA) 13 Apr: Compare power performance of LCD and EPD given sequence of images and power optimization schemes