Low-power motion gesture sensor with a partially open cavity package

Abstract

In an IR proximity-based motion gesture sensor (MGS) mainly composed of an IR LED and photodiodes (PDs), the IR LED is the most power-hungry component. For reducing its power, both the size and the field-of-view (FOV) of each PD can be increased instead. However, it cannot be adapted to conventional MGSs due to the geometrical limitation of their optical structures. In this paper, the optical structure of the proposed MGS with a partially open cavity package allows for power reduction by at least 70.9% compared with conventional MGSs. Optical simulation and test results validate the theoretical analysis presented.

Analysis of Properties of an Active Linear Gesture Sensor

“…Therefore, due to a relatively low sampling rate the current consumption is lower than that reported for many optical sensors in the literature, which can be found in a range of 10-20 mA [4, 9, 10, 11] but 3.78 mA sensors were reported as well [12] (all solutions with 1 LED, enclosed in a single chip). The power consumption was found to be around 8 mW [13,14], but many sensors consume more than 20 mW [8,13].…”

“…The third type are sensors with several detectors, excluding matrices of detectors, like RGB cameras. Kong et al have proposed three-detector MGSs with [11] and without [12] optical blocks enclosed in a single chip, handling swipes in 3D. Withana et al have proposed a modular sensor composed of photodiode-LED pairs [13], which can be arranged in a linear or triangular form.…”

The Passive Operating Mode of the Linear Optical Gesture Sensor

“…However, the feature of continuous hand pose localization in relation to the sensor, as in [19], makes the linear gesture sensor an attractive solution among other basic sensors. It is a considerable advantage over some sensors that support only discrete gestures [9,20,23].…”

“…The typical power utilization of the basic active gesture sensors is at the milliwatts order of magnitude like in the Okuli device, which can be reduced to circa 100 mW [8] or 3.78 mA in the partially open cavity package sensor [9].…”

“…Thus what is of interest are sensors relying on a less robust computation that could handle a rich set of gestures with a high recognition accuracy along with a lower power consumption. Many of them are active sensors utilizing the excitation of a given type, such as optical [8][9][10][11] or radio wave sensors [12,13]. Yet passive solutions of gesture sensors based on many kinds of transducers have also been widely presented.…”