As shown in FIG. 4, the sensing unit 221 can rotate about the Z axis, and the sensing unit 221 can rotate to a first angle and a second angle. However, this present disclosure does not limit the central axis which the sensing unit 221 rotates about to be the Z axis. The central axis about rotation can be changed to other directions. In this embodiment, the first angle corresponds to a normal operation status. As shown in FIG. 4, the Z axis is taken as the rotation central axis, and the first angle is towards the positive direction of the X-axis (+X), such that the sensing unit 221 can sense signals such as the exterior light, infrared or microwave reflections through the lens 2211B. In one embodiment, for outdoor applications, when the sensing unit 221 is rotated to the first angle, the sensor 2211 and the cover 222 can further form an enclosed space 2220 to cover the control circuit 2212 and the operating parameter adjusting element 2213. Therefore, waterproof and dustproof efficacy can be achieved.