Capacitance change detection device
First Claim
1. A capacitance change detection device comprising:
- a sensor electrode at which capacitance varies;
an electrode capacitance measurement means for measuring capacitance of the sensor electrode on the basis of a correlation value based on a predetermined reference capacitance at every first predetermined time;
wherein a detection signal is generated when a current measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means is changed by equal to or greater predetermined threshold value than a measurement value obtained a second predetermined time before a timing that the current measurement value is measured;
a predetermined sensitivity compensation capacitance for generating capacitance variations equivalent to a specific variations of capacitance of the sensor electrode generated by existence of a specific object at capacitance of the sensor electrode;
wherein the sensitivity compensation capacitance is configured to be switched between a connected state at which the sensitivity compensation capacitance is connected to the sensor electrode and a disconnected state at which the sensitivity compensation capacitance is disconnected from the sensor electrode; and
the threshold value is determined as a difference between a measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means at the connected state and a measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means at the disconnected state; and
the threshold value is configured to be renewed at every third predetermined time.
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Accused Products
Abstract
A capacitance change detection device includes a sensor electrode, and an electrode capacitance measurement device for measuring capacitance of the sensor electrode on the basis of a correlation value based on a reference capacitance at every first predetermined time. A detection signal is generated when a current measurement value of capacitance is changed by equal to or greater predetermined threshold value than a measurement value obtained a second predetermined time before the current measurement value is measured. The capacitance change detection device further includes a sensitivity compensation capacitance for generating capacitance variations equivalent to specific variations of capacitance of the sensor electrode, and being switched between a connected state and a disconnected state. The threshold value is determined as a difference between measurement values of capacitance of the sensor electrode measured at the connected state and at the disconnected state. The threshold value is renewed at every third predetermined time.
73 Citations
4 Claims
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1. A capacitance change detection device comprising:
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a sensor electrode at which capacitance varies;
an electrode capacitance measurement means for measuring capacitance of the sensor electrode on the basis of a correlation value based on a predetermined reference capacitance at every first predetermined time;
whereina detection signal is generated when a current measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means is changed by equal to or greater predetermined threshold value than a measurement value obtained a second predetermined time before a timing that the current measurement value is measured;
a predetermined sensitivity compensation capacitance for generating capacitance variations equivalent to a specific variations of capacitance of the sensor electrode generated by existence of a specific object at capacitance of the sensor electrode;
whereinthe sensitivity compensation capacitance is configured to be switched between a connected state at which the sensitivity compensation capacitance is connected to the sensor electrode and a disconnected state at which the sensitivity compensation capacitance is disconnected from the sensor electrode; and
the threshold value is determined as a difference between a measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means at the connected state and a measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means at the disconnected state; and
the threshold value is configured to be renewed at every third predetermined time. - View Dependent Claims (3)
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2. A capacitance change detection device comprising:
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a sensor electrode at which capacitance is varied;
an electrode capacitance measurement means for measuring capacitance of the sensor electrode on the basis of a correlation value based on a predetermined reference capacitance at every first predetermined time;
whereina detection signal is generated when a current measurement value of capacitance of the sensor electrode measured by the electrode capacitance measurement means is changed by equal to or greater predetermined threshold value than a measurement value obtained a second predetermined time before a timing that the current measurement value is measured;
and wherein the threshold value is determined as a value which is determined on the basis of the measurement value measured the second predetermined time before the time of the measurement. - View Dependent Claims (4)
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Specification