Electrophoretic Display Power and Mobile Computing Devices

Michael A. BakerMarch 4, 2007

CSE 591 Low Power Computer ArchitectureInstructor: Aviral Shrivastava

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Agenda

• Introduction

• Mobile computing device displays

• Electrophoretic displays

• LCD power management schemes

• Power modeling

• References

• Timeline

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Mobile Computing Device Display Technologies

Mobile Computing Device Display Technologies

Non-EmissiveEmissive

OLED(Organic Light Emitting Diode)

SRD(Scanning Retinal

Displays)

PLED(Polymer based

OLED)

SMOLED(Polymer based

OLED)

ElectrophoreticLCD

(Liquid Crystal Display)

Active Matrix Passive Matrix

IMOD(Inferometric Modulator)

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Display Technology

© 2007 QUALCOMM MEMS Technologies, Inc.

LCD Electrophoretic Displays OLED

LCD

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Electrophoretic Display Process

© 2007 QUALCOMM MEMS Technologies, Inc.

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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

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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

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Calculating LCD Power Consumption

• Representation of display driver and LCD pixels

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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

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Primary References

• [1] Pedram, 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, 2006

• [3] Zhong, Jha, Graphical User Interface Energy Characterization for Handheld Computers, October 2003

• [4] Dalisa, Electrophoretic Display Technology, 1977• [5] Gatti, Acquaviva, Benini, Ricco’, Low Power Control Techniques For

TFT LCD Displays, 2002• [6] Marks, Power Consumption in Multiplexed Liquid-Crystal Displays,

1982

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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