Infrared Detection of Elevations in Mobile Phone Temperatures Induced by Casings

Abstract

The design and utility of mobile handheld devices have developed tremendously, from being initially intended for audio calls only to the recent incorporation of augmented reality in smartphones. Recent smartphone functions are power intensive, and cause excessive heating in phone parts, primarily batteries and processors. Left unmanaged, phone temperatures would exceed the threshold temperature of discomfort, negatively affecting user experience. The use of phone casings has simultaneously become common in recent years. They form an additional barrier to heat dissipation from mobile devices, which has not been considered in existing studies. In this work, the thermal profiles of two identical smartphones were assessed during common tasks, including music playing, voice calling, video streaming and 3D online gaming. One of the phones (the test case) was operated while enclosed in a plastic phone casing, while the other (the control case) was bare. Transient surface temperature distributions were obtained with infrared imaging and thermocouple sensors, while processor and battery temperatures were obtained from inbuilt sensors. Test results showed that casings generally redirect the dissipation of the heat generated within the phone. For tasks involving contact with users' hands, this will protect the user from high phone surface temperatures. However, the processor and battery temperatures are increased as a result. This user protection was not achieved in the online gaming task, for which the heat generated exceeded the insulating capacity of the plastic casing. The range of protection offered to phone users could be extended by using phone casings which incorporate phase change materials.