CLEANING DEVICE, IMAGING UNIT EQUIPPED WITH CLEANING DEVICE, AND CLEANING METHOD

A cleaning device includes a protection cover, a vibrator, a piezoelectric driver, and a signal processing circuit. When the signal processing circuit determines that foreign matter is adhered to a surface of the protection cover, it controls the piezoelectric driver such that vibration of the protection cover has a vibration acceleration of about 1.5×10m/s. When the signal processing circuit determines that the foreign matter is adhered to the surface of the protection cover when control of the driver such that vibration of the protection cover has a prescribed vibration acceleration, the protection cover is warmed with a warmer. After the protection cover is warmed, the signal processing circuit controls the piezoelectric driver such that vibration of the protection cover has a resonant frequency.