Abstract: A method of driving a vibration device including a light-transmitting body and a piezoelectric element connected to the light-transmitting body is provided to vibrate the light-transmitting body. The method atomizes and removes liquid drops sticking to the light-transmitting body. A driving voltage to vibrate the piezoelectric element is swept at a sweep speed in a range of about 1 Hz to about 50 Hz so as to sweep a vibration frequency of the piezoelectric element to cover a frequency range including both of a resonant frequency of the light-transmitting body without liquid drops sticking to the light-transmitting body and a resonant frequency of the light-transmitting body with the liquid drops sticking to the light-transmitting body.

Abstract: A method of driving a vibration device including a light-transmitting body and a piezoelectric element connected to the light-transmitting body is provided to vibrate the light-transmitting body. The method atomizes and removes liquid drops sticking to the light-transmitting body. A driving voltage to vibrate the piezoelectric element is swept at a sweep speed in a range of about 1 Hz to about 50 Hz so as to sweep a vibration frequency of the piezoelectric element to cover a frequency range including both of a resonant frequency of the light-transmitting body without liquid drops sticking to the light-transmitting body and a resonant frequency of the light-transmitting body with the liquid drops sticking to the light-transmitting body.

Abstract: An ultrasonic sensor includes a piezoelectric body including a transmission region for an ultrasonic wave and a reception region for a reflected wave of the ultrasonic wave, a common electrode in the transmission region and the reception region, a transmission electrode in the transmission region, a reception electrode in the reception region; and a semiconductor element that is electrically connected to the transmission electrode and the reception electrode and switches an electrical path between a conductive state and a non-conductive state. The semiconductor element puts the path into the conductive state after application of the alternating-current voltage is stopped. Thus, a reverberation signal, output from the reception region in accordance with a reverberant vibration of the ultrasonic wave, is fed back to the transmission electrode.

Abstract: An ultrasonic sensor includes a piezoelectric body including a transmission region for an ultrasonic wave and a reception region for a reflected wave of the ultrasonic wave, a common electrode in the transmission region and the reception region, a transmission electrode in the transmission region, a reception electrode in the reception region; and a semiconductor element that is electrically connected to the transmission electrode and the reception electrode and switches an electrical path between a conductive state and a non-conductive state. The semiconductor element puts the path into the conductive state after application of the alternating-current voltage is stopped. Thus, a reverberation signal, output from the reception region in accordance with a reverberant vibration of the ultrasonic wave, is fed back to the transmission electrode.

Abstract: An external-force detecting apparatus includes at least one drive line connecting the corresponding drive electrodes to a driving unit and at least one monitor line connecting the corresponding monitor electrodes to the driving unit. The driving unit outputs a drive signal to the at least one of the drive electrodes through the at least one of the drive lines to drive an oscillator and performs automatic gain control to the level of the drive signal based on the oscillation state of the oscillator acquired from the at least one of the monitor electrodes through the at least one of the monitor lines. The external-force detecting apparatus further includes a switching circuit arranged to switch between connection and disconnection of an electric path between the oscillator and the driving unit via at least one of the drive lines or the multiple monitor lines.

Abstract: An external-force detecting apparatus includes at least one drive line connecting the corresponding drive electrodes to a driving unit and at least one monitor line connecting the corresponding monitor electrodes to the driving unit. The driving unit outputs a drive signal to the at least one of the drive electrodes through the at least one of the drive lines to drive an oscillator and performs automatic gain control to the level of the drive signal based on the oscillation state of the oscillator acquired from the at least one of the monitor electrodes through the at least one of the monitor lines.