The LED cap light has a housing with an arcuate top surface. The controller includes a management table for managing the number of failure areas in a predetermined unit that occur in the second storing unit and switches, according to the number of failure areas, an operation mode in writing data in the second storing unit from the host apparatus. The interval between two adjacent outputted PWM signals is T1, which is the time when the current required by an electric device is higher than the normal current in case of an increase of the duty cycle of the PWM signals. The spacer includes linkages that are attached to a pair of plates. Additionally, the housing may be configured to visually shield the tilt assembly from observers.