Proximity Sensing Based on a Dynamic Vision Sensor for Mobile Devices
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2014 IEEE. A dynamic vision sensor (DVS) is a sensor that detects temporal contrast of brightness and has the fastest response time compared to conventional frame-based sensors, which detect static brightness per every frame. The fastest response time allows fast motion recognition, which is a very attractive function in the view of consumers. In particular, its low power consumption due to the event-based processing is a key feature for mobile applications. In recent smartphones based on touch screen, a proximity sensor is equipped to prevent malfunction due to undesired contacts with skin while calling. In addition, the main processor stops the operation of the touch screen and turns off the display, when any object is close to the proximity sensor, to achieve minimizing power consumption. Considering the importance of the power consumption and reliable operations, it is certain that proximity sensing is an essential part in a touch-screen-based smartphone. In this paper, a design of proximity sensing utilizing a DVS is proposed. It can estimate the distance from the DVS to an object by analyzing the spatial information of the reflection of an additional light source. It also uses a pattern recognition based on time-domain analysis of the reflection, during turning on of the light source, to avoid wrong proximity detection by noises such as other light sources and motions. The contributions of the proposed design are in three parts. First, it calculates the accurate distance in real time only with spatial information of the reflection. Second, the proposed design can eliminate environmental noises by using pattern matching based on time-domain analysis, whereas conventional optical proximity sensors, which are mainly used in smartphones, are very sensitive to environmental noises because they use the total amount of brightness for certain periods. Third, our design replaces conventional proximity sensors by holding additional benefits that it utilizes the advantages of DVS.