DISPLACEMENT DETECTION DEVICE AND DISPLACEMENT DETECTION METHOD
First Claim
1. A displacement detection device comprising:
- a piezoelectric sensor including a piezoelectric substance and a pair of detection electrodes disposed on opposing surfaces of the piezoelectric substance;
a voltage detector configured to measure a voltage generated by the piezoelectric sensor in response to to displacement of the piezoelectric substance;
a switch coupled between the pair of detection electrodes; and
a controller configured to open the switch for the voltage detector to measure the voltage generated by the piezoelectric sensor,wherein the controller is coupled to the voltage detector to detect an output voltage from the voltage detector and further configured to short-circuit the switch for a predetermined period of time after detecting the output voltage, andwherein the controller is further configured to calculate an amount of displacement of the piezoelectric sensor based on the output voltage detected from the voltage detector.
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Abstract
A displacement detection device includes a piezoelectric sensor. The piezoelectric sensor is provided with a piezoelectric sheet on both principal surfaces of which detection electrodes are formed. When stress is applied to the piezoelectric sensor, charge is generated, and an output voltage in accordance with this generated charge is detected in a DC voltage detector. A controller measures this output voltage at a predetermined time interval. Every time the controller measures the output voltage, the controller makes a short-circuit control of a switch, and causes the charge generated in the piezoelectric sensor to be released. The controller can thereby detect an amount of change in output voltage generated at the predetermined time interval in accordance with an amount of displacement of the piezoelectric sensor. By sequentially integrating this, the controller can accurately detect the amount of displacement of the piezoelectric sensor which changes across measurement timings.
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Citations
20 Claims
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1. A displacement detection device comprising:
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a piezoelectric sensor including a piezoelectric substance and a pair of detection electrodes disposed on opposing surfaces of the piezoelectric substance; a voltage detector configured to measure a voltage generated by the piezoelectric sensor in response to to displacement of the piezoelectric substance; a switch coupled between the pair of detection electrodes; and a controller configured to open the switch for the voltage detector to measure the voltage generated by the piezoelectric sensor, wherein the controller is coupled to the voltage detector to detect an output voltage from the voltage detector and further configured to short-circuit the switch for a predetermined period of time after detecting the output voltage, and wherein the controller is further configured to calculate an amount of displacement of the piezoelectric sensor based on the output voltage detected from the voltage detector. - 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 displacement detection method for detecting an amount of displacement of a piezoelectric sensor from an output voltage of the piezoelectric sensor, the method comprising:
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setting a storage voltage for displacement calculation as a reference voltage; measuring an output voltage of the piezoelectric sensor at a predetermined interval to obtain a measured voltage; calculating a displacement voltage as a difference between the measured voltage and the reference voltage; resetting the measured voltage to the reference voltage after calculating the displacement voltage; sequentially integrating the displacement voltages to the reference voltage while updating and storing the obtained voltage as the storage voltage; and calculating the amount of displacement from the storage voltage. - View Dependent Claims (19, 20)
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Specification