Patent attributes
An optical apparatus (camera) having dust-off function comprises a dust-off glass (optical element) located between an image-pickup element and optical system (lens) for forming an image on the light receiving surface of the element. A camera includes a mechanism (piezoelectric element and drive circuit) that controls vibrating operation so that the frequency of vibration waves generated in the glass changes with the passage of time. A camera includes first vibrator (piezoelectric element) for successive vibration with frequencies, a circuit monitoring the state of vibration of the optical element during vibrating operation of the first vibrator, thereby detecting the resonance frequency of the element, and second vibrator (piezoelectric element) for vibration with the detected resonance frequency or a frequency approximate to it. A camera includes monitor (electrode) for monitoring the state of vibration of the glass and a circuit for detecting abnormal states in accordance with output signals from the electrode.
