Energy Efficient Hybrid Display for Embedded and Mobile Systems



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Embedded and mobile devices, such as smartphones, e-books, and tablets, have limited battery capability because of the constraint of battery size and mobility requirement. However the large color display on those devices put more tensions on this situation as the display consumes a large portion of the total battery power.

Electrophoretic displays (EPDs) and organic light-emitting diodes (OLEDs) are two key technologies used on embedded and mobile devices. We propose the design of an integrated hybrid display combining a transparent OLED (TOLED) and a low-power EPD, which is adaptive to show contents of a frame partially on either the TOLED or the EPD. A windows-based predictive model and a calibration algorithm on TOLED are introduced to decide how frame contents can be split between the two displays for achieving the best tradeoff between power reduction and user experiences.

In addition to regular contents, we also propose a design of mobile video playback, Decoder4Hybrid , for the hybrid displays to play realtime videos. A fast DCT(Discrete Cosine Transform)-based heuristic algorithm is proposed to detect the changes between frames at block level with minimal computation cost.

A simulation environment that can estimate both the energy consumption and optical properties of the proposed hybrid display is set up based on actual physical measurements. Simulation results show that the predictive model can make right decisions on choosing proper displays in over 90% of the test cases, and this new display design can save over 70% power under many mobile application contexts and still support contents that require fast update rates. Experimental results show that the proposed approach can save up to 40% power with acceptable video quality.



Energy Efficient, Hybrid Display, Embedded systems, Mobile Systems