Ultrasonic sensor and control method therefor
First Claim
1. An ultrasonic sensor comprising:
- a piezoelectric element including;
a flat plate-shaped piezoelectric body that includes a transmission region that transmits an ultrasonic wave in response to an alternating current voltage being applied thereto and a reception region that receives a reflected wave of the ultrasonic wave;
a common electrode that is provided in the transmission region and the reception region;
a transmission electrode that faces the common electrode with the transmission region interposed therebetween and that is provided in the transmission region; and
a reception electrode that faces the common electrode with the reception region interposed therebetween and that is provided 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 extending between the transmission electrode and the reception electrode between a conductive state and a non-conductive state;
whereinthe semiconductor element puts the electrical path into the conductive state after application of the alternating current voltage is stopped, and as a result, 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.
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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.
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Citations
20 Claims
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1. An ultrasonic sensor comprising:
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a piezoelectric element including; a flat plate-shaped piezoelectric body that includes a transmission region that transmits an ultrasonic wave in response to an alternating current voltage being applied thereto and a reception region that receives a reflected wave of the ultrasonic wave; a common electrode that is provided in the transmission region and the reception region; a transmission electrode that faces the common electrode with the transmission region interposed therebetween and that is provided in the transmission region; and a reception electrode that faces the common electrode with the reception region interposed therebetween and that is provided 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 extending between the transmission electrode and the reception electrode between a conductive state and a non-conductive state;
whereinthe semiconductor element puts the electrical path into the conductive state after application of the alternating current voltage is stopped, and as a result, 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A control method for an ultrasonic sensor, the ultrasonic sensor including a piezoelectric element, the piezoelectric element including a flat plate-shaped piezoelectric body that includes a transmission region that transmits an ultrasonic wave in response to an alternating current voltage being applied thereto and a reception region that receives a reflected wave of the ultrasonic wave, a common electrode that is provided in the transmission region and the reception region, a transmission electrode that faces the common electrode with the transmission region interposed therebetween and that is provided in the transmission region, and a reception electrode that faces the common electrode with the reception region interposed therebetween and is provided in the reception region, the ultrasonic sensor further including a semiconductor element that is electrically connected to the transmission electrode and the reception electrode and switches an electrical path extending between the transmission electrode and the reception electrode between a conductive state and a non-conductive state, the control method comprising:
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putting the electrical path into the non-conductive state; applying an alternating current voltage to the transmission region after the electrical path has been put into the non-conductive state; and feeding a reverberation signal, which is output from the reception region in accordance with a reverberant vibration of the ultrasonic wave, back to the transmission electrode by putting the electrical path into the conductive state after stopping application of the alternating current voltage. - View Dependent Claims (19, 20)
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Specification