Patent attributes
A detector made of lanthanum-doped lead zirconate titanate detects intensity of ultraviolet light radiated inside of a vehicle. The detector sends ultrasonic wave to an incidence direction of ultraviolet light, and detects ultrasonic wave reflected by an object. An electrical unit determines the object to be an occupant of the vehicle or not based on the reflected ultrasonic wave. The electrical unit outputs a signal representing that a predetermined or more amount of ultraviolet light is radiated to the occupant, when the detector detects the predetermined or more amount of ultraviolet light and when the electrical unit determines the object to be the occupant.