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 one or more signals generated by a piezo-electric type accelerometer in response to detection of a shock applied to an object to which the piezo-electric type accelerometer is connected, wherein the method comprises the steps of:
- generating a signal by a piezo-electric type accelerometer in response to detection of a shock applied to an object connected to the piezo-electric type accelerometer; and
filtering, during a second step, the signal generated by the piezo-electric type accelerometer to ensure that, after having increased and exceeded a first threshold value, the signal decreases and becomes lower than a second threshold value that is lower than the first threshold value after a first period of time greater than a minimum period of time and less than a maximum period of time.
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Abstract
The invention concerns 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, this method characterised in that it ensures, during a particular 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). The invention also concerns a device for filtering signals generated by an accelerometer in response to detection of a shock applied to an object connected to the accelerometer. Finally, the invention concerns a portable object such as a wristwatch including a detection device of this kind.
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Citations
24 Claims
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1. A method for filtering one or more signals generated by a piezo-electric type accelerometer in response to detection of a shock applied to an object to which the piezo-electric type accelerometer is connected, wherein the method comprises the steps of:
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generating a signal by a piezo-electric type accelerometer in response to detection of a shock applied to an object connected to the piezo-electric type accelerometer; and filtering, during a second step, the signal generated by the piezo-electric type accelerometer to ensure that, after having increased and exceeded a first threshold value, the signal decreases and becomes lower than a second threshold value that is lower than the first threshold value after a first period of time greater than a minimum period of time and less than a maximum period of time. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A device for filtering signals generated by a piezo-electric type accelerometer in response to detection of a shock applied to an object to which the piezo-electric type accelerometer is connected, wherein this device includes:
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comparison means for comparing a level of a voltage signal generated by a piezo-electric type accelerometer, connected to the object, to a first threshold level and a second threshold level; means for switching on a time base, wherein the time base is actuated by the means for switching on the time base when the level of the voltage signal from the piezo-electric type accelerometer supplied to the comparison means is higher than the first threshold level; a generator of reference time periods controlled by the time base; and means for checking, over time, an output level of the comparison means in relation to the reference periods of time provided by the generator to determine whether a shock applied to the object is valid or not. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification