Ultrasonic sensor
First Claim
1. An ultrasonic sensor comprising:
- a piezoelectric vibrator which vibrates to transmit an ultrasonic wave, receives a reflected wave of the transmitted ultrasonic wave and produces an output signal corresponding to vibration of the piezoelectric vibrator;
a reverberation measuring means for measuring a reverberation period of the piezoelectric vibrator from the output signal; and
a compensating means for compensating for an operation characteristic of the piezoelectric vibrator in accordance with the measured reverberation period, whereinthe compensating means compensates for the operation characteristic of the piezoelectric vibrator so that the reverberation period is adjusted to be the shortest when the reverberation period measured by the reverberation measuring means is not within a predetermined range.
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Accused Products
Abstract
An ultrasonic sensor includes a piezoelectric vibrator, a reverberation measuring device and a compensating device. The piezoelectric vibrator vibrates to transmit an ultrasonic wave, receives a reflected wave of the transmitted ultrasonic wave and produces an output signal corresponding to vibration of the piezoelectric vibrator. The reverberation measuring device measures a reverberation period of the piezoelectric vibrator from the output signal. The compensating device compensates for an operation characteristic of the piezoelectric vibrator in accordance with the measured reverberation period. Thus, the ultrasonic sensor can decrease a reverberation period, which may cause reduction in detection accuracy and impossibility of detection of an obstacle at a short distance.
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Citations
24 Claims
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1. An ultrasonic sensor comprising:
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a piezoelectric vibrator which vibrates to transmit an ultrasonic wave, receives a reflected wave of the transmitted ultrasonic wave and produces an output signal corresponding to vibration of the piezoelectric vibrator; a reverberation measuring means for measuring a reverberation period of the piezoelectric vibrator from the output signal; and a compensating means for compensating for an operation characteristic of the piezoelectric vibrator in accordance with the measured reverberation period, wherein the compensating means compensates for the operation characteristic of the piezoelectric vibrator so that the reverberation period is adjusted to be the shortest when the reverberation period measured by the reverberation measuring means is not within a predetermined range. - View Dependent Claims (2, 3, 4)
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5. An ultrasonic sensor comprising:
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a piezoelectric vibrator which vibrates to transmit an ultrasonic wave, receives a reflected wave of the transmitted ultrasonic wave and produces an output signal corresponding to vibration of the piezoelectric vibrator; a reverberation measuring means for measuring a reverberation period of the piezoelectric vibrator from the output signal; and a compensating means for compensating for an operation characteristic of the piezoelectric vibrator in accordance with the measured reverberation period, wherein the compensating means normally compensates for the operation characteristic of the piezoelectric vibrator so that the reverberation period is adjusted to be the shortest. - View Dependent Claims (6, 7, 8)
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9. An ultrasonic sensor comprising:
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a piezoelectric vibrator which vibrates to transmit an ultrasonic wave, receives a reflected wave of the transmitted ultrasonic wave and produces an output signal corresponding to vibration of the piezoelectric vibrator; a reverberation measuring means for measuring a reverberation period of the piezoelectric vibrator from the output signal; and a compensating means for compensating for an operation characteristic of the piezoelectric vibrator in accordance with the measured reverberation period, wherein; the compensating means includes at least one of a capacitor and a coil; the compensating means compensates for the operation characteristic of the piezoelectric vibrator by changing a combination of the capacitor and the coil which are connected to the piezoelectric vibrator; the reverberation measuring means measures a reverberation period of the piezoelectric vibrator for all or some of combinations of the capacitor and the coil which are connected to the piezoelectric vibrator; and the compensating means selects a combination from the combinations of the capacitor and the coil connected to the piezoelectric vibrator, whose reverberation periods are measured by the reverberation measuring means. - View Dependent Claims (10, 11, 12)
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13. An ultrasonic sensor comprising:
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a piezoelectric vibrator which vibrates to transmit an ultrasonic wave, receives a reflected wave of the transmitted ultrasonic wave and produces an output signal corresponding to vibration of the piezoelectric vibrator; a reverberation measuring means for measuring a reverberation period of the piezoelectric vibrator from the output signal; and a compensating means for compensating for an operation characteristic of the piezoelectric vibrator in accordance with the measured reverberation period, wherein; the compensating means includes at least one of a capacitor and a coil; the compensating means compensates for the operation characteristic of the piezoelectric vibrator by changing a combination of the capacitor and the coil which are connected to the piezoelectric vibrator; the ultrasonic sensor is mounted in a vehicle in order to detect an obstacle around the vehicle; and the compensating means changes the combination of the capacitor and the coil connected to the piezoelectric vibrator when a speed of the vehicle is more than a predetermined value. - View Dependent Claims (14, 15, 16)
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17. An ultrasonic sensor comprising:
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a piezoelectric vibrator which vibrates to transmit an ultrasonic wave, receives a reflected wave of the transmitted ultrasonic wave and produces an output signal corresponding to vibration of the piezoelectric vibrator; a reverberation measuring means for measuring a reverberation period of the piezoelectric vibrator from the output signal; and a compensating means for compensating for an operation characteristic of the piezoelectric vibrator in accordance with the measured reverberation period, wherein; the compensating means includes at least one of a capacitor and a coil; and the compensating means compensates for the operation characteristic of the piezoelectric vibrator by changing a combination of the capacitor and the coil which are connected to the piezoelectric vibrator; the ultrasonic sensor is mounted on a front side of a vehicle in order to detect an obstacle in front of the vehicle; and the compensating means changes the combination of the capacitor and the coil connected to the piezoelectric vibrator when the vehicle moves back. - View Dependent Claims (18, 19, 20)
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21. An ultrasonic sensor comprising:
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a piezoelectric vibrator which vibrates to transmit an ultrasonic wave, receives a reflected wave of the transmitted ultrasonic wave and produces an output signal corresponding to vibration of the piezoelectric vibrator; a reverberation measuring means for measuring a reverberation period of the piezoelectric vibrator from the output signal; and a compensating means for compensating for an operation characteristic of the piezoelectric vibrator in accordance with the measured reverberation period, wherein; the compensating means includes at least one of a capacitor and a coil; and the compensating means compensates for the operation characteristic of the piezoelectric vibrator by changing a combination of the capacitor and the coil which are connected to the piezoelectric vibrator; the ultrasonic sensor is mounted on a rear side of a vehicle in order to detect an obstacle behind the vehicle; and the compensating means changes the combination of the capacitor and the coil connected to the piezoelectric vibrator when the vehicle moves forward. - View Dependent Claims (22, 23, 24)
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Specification