1. Adjust the brightness of the display: Fitness trackers and smart watches are equipped with ambient light sensors. The main job of the X-ray watch sensor is to adjust the brightness of the display according to the surrounding light, which also helps to save battery life.

2. Tracking direction: Three-axis accelerometer is the sensor of wearable device, axial accelerometer detects motion and tracks direction, and X-ray watch sensor can track back and forth motion, sense gravity and determine the direction, position and speed change rate of the body.