Monitoring system and method
First Claim
Patent Images
1. A monitoring system comprising:
- a piezoelectric device which is subject to dynamic and static forces whose magnitude is to be monitored and which generates a signal for a change of force; and
a second device including a switch having a first state and a second state for switching the second device between a first mode corresponding to the first state and second mode corresponding to the second state for detecting signals generated by the piezoelectric device and determining the magnitude of force from the detected signal for dynamic forces in a first mode, and determining the impedance of the piezoelectric device and determining the magnitude of force from the impedance for static forces in a second mode.
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Abstract
A system including piezoelectric material wherein a force exerted on the piezoelectric material is determined by subjecting the piezoelectric material to an input signal of sweeping frequency and evaluating the response of the piezoelectric material to the applied signal.
89 Citations
67 Claims
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1. A monitoring system comprising:
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a piezoelectric device which is subject to dynamic and static forces whose magnitude is to be monitored and which generates a signal for a change of force; and
a second device including a switch having a first state and a second state for switching the second device between a first mode corresponding to the first state and second mode corresponding to the second state for detecting signals generated by the piezoelectric device and determining the magnitude of force from the detected signal for dynamic forces in a first mode, and determining the impedance of the piezoelectric device and determining the magnitude of force from the impedance for static forces in a second mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A monitoring method comprising:
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providing a piezoelectric device which is subject to dynamic and static forces whose magnitude is to be monitored and which generates a signal for a change of force;
detecting signals generated by the piezoelectric device for dynamic forces;
determining the magnitude of force from the detected signal for dynamic forces;
determining the impedance of the piezoelectric device for static forces if the generated signals are not detected; and
determining the magnitude of force from the impedance for static forces. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63)
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64. A monitoring system comprising:
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a piezoelectric device which is subject to a force whose magnitude is to be monitored and which generates a signal for a change of force; and
a second device for detecting a relatively large signal generated by the piezoelectric device, determining if the signal generated by the piezoelectric device after the detected relatively large signal varies at a predetermined rate over a predetermined time, and if so, concluding that an object is still exerting force on the piezoelectric device.
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65. A monitoring system comprising:
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a piezoelectric device which is subject to a force whose magnitude is to be monitored and which generates a signal for a change of force; and
a second device switching between a first mode and second mode for detecting a relatively large signal generated by the piezoelectric device and determining if the signal generated by the piezoelectric device after the detected relatively large signal decreases over a brief time interval below some minimum threshold in a first mode, and if so, determining if a relatively constant force is being applied in a second mode.
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66. A monitoring method comprising:
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providing a piezoelectric device which is subject to a force whose magnitude is to be monitored and which generates a signal for a change of force;
detecting a relatively large signal generated by the piezoelectric device;
determining if the signal generated by the piezoelectric device after the detected relatively large signal varies at a predetermined rate over a predetermined time; and
if so, concluding that an object is still exerting force on the piezoelectric device.
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67. A monitoring method comprising:
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providing a piezoelectric device which is subject to a force whose magnitude is to be monitored and which generates a signal for a change of force;
detecting a relatively large signal generated by the piezoelectric device;
determining if the signal generated by the piezoelectric device after the detected relatively large signal decreases over a brief time interval below some minimum threshold; and
if so, determining if a relatively constant force is being applied.
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Specification