An optical scanning device includes a mirror that oscillates to scan incident visible light. This design introduces a bias layer in to the HEMT allowing the transistor to be fed with alternating current alone without the need for a negative direct current bias power supply. Then, a notification process for reminding the user of the schedule for the pending undertaking is performed under appropriate conditions. At that time, since the reference voltage is higher than the voltage for turning on both a second transistor and a diode, a current flows and the first transistor turns on.