FlexDisplay: An Optimized Smartphone Display Framework To Conserve Battery Power

Despite significant improvements, smartphones are still constrained by the limited capacity of their batteries. Modern smartphones tend to use organic light-emitting diode (OLED) displays, whose energy consumption depends both on the brightness and the color content. Since the display of smartphones is known to consume a significant portion of this energy, a number of prior systems have tried to reduce screen brightness, increase areas of dark zones on the screen or use colors that consume less energy to mitigate this problem. However, the amount of energy savings using these techniques are still limited, as the underlying compute required to render the content still consumes energy. In this work, we provide a framework FlexDisplay that disables the display of a limited portion of the app content, saves the underlying compute needed to render the content as well as the touch sensors in the corresponding display area. FlexDisplay supports disabling of content across multiple apps. We implement FlexDisplay on two different smartphones. We demonstrate it on 15 apps over different genres and show that the energy savings vary from 10%–47% of the total energy consumption of the smartphone, depending on the app and the disabled content. Furthermore, we show via user studies on 20 users that the changes made by FlexDisplay do not hurt their experience significantly.