Method and device for filtering signals produced by an accelerometer of the piezo-electric type, and application to a portable object such as a watch
First Claim
1. A method for filtering signals (VIN) generated by a piezo-electric type accelerometer in response to detection of a shock applied to an object to which the accelerometer is connected, wherein it is ensured, during a first step, that the signal (VIN) generated by the accelerometer, after having increased and exceeded a first threshold value (VTH,ON) decreases and becomes lower than a second threshold value (VTH,OFF) lower than the first threshold value (VTH,ON) after a period of time (TP,ON) greater than a minimum period of time (TP,ON,MIN) and less than a maximum period of time (TP,ON,MAX):
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Abstract
The present invention concerns a method for filtering signals (VIN) generated by a piezo-electric type accelerometer (34) in response to detection of a shock applied to an object to which the accelerometer is connected, this method being characterised in that it is ensured, during a first step, that the signal (VIN) generated by the accelerometer (34), after having increased and exceeded a first threshold value (VTH,ON) decreases and becomes lower than a second threshold value (VTH,OFF) lower than the first threshold value (VTH,ON) after a period of time (TP,ON) greater than a minimum period of time (TP,ON,MIN) and less than a maximum period of time (TP,ON,MAX). The invention also concerns a device for filtering the signals generated by an accelerometer in response to detection of a shock applied to an object to which the accelerometer is connected. Finally, the invention concerns a portable object such as a wristwatch including a detection device of this kind.
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Citations
23 Claims
- 1. A method for filtering signals (VIN) generated by a piezo-electric type accelerometer in response to detection of a shock applied to an object to which the accelerometer is connected, wherein it is ensured, during a first step, that the signal (VIN) generated by the accelerometer, after having increased and exceeded a first threshold value (VTH,ON) decreases and becomes lower than a second threshold value (VTH,OFF) lower than the first threshold value (VTH,ON) after a period of time (TP,ON) greater than a minimum period of time (TP,ON,MIN) and less than a maximum period of time (TP,ON,MAX):
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8. A device for filtering signals (VIN) generated by a piezo-electric type accelerometer in response to detection of a shock applied to an object to which the accelerometer is connected, wherein this device includes:
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comparison means for comparing the level of the signal (VIN) generated by the accelerometer to a first and a second threshold level (VTH,ON;
VTH,OFF);
means for switching on a time base, which is actuated when the level of the signal (VIN) from the accelerometer supplied to the comparison means is higher than the first threshold level (VTH,ON);
a generator of reference time periods controlled by the time base, and means for checking over time the output level (OUT(COMP)) of the comparison means in relation to the reference periods of time provided by the generator to determine whether the shock applied to the object was valid or not. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification