Capacitance voltage conversion circuit, input apparatus using the same, electronic instrument, and capacitance voltage conversion method
First Claim
1. A capacitance voltage conversion circuit which converts a capacitance of each of a plurality of sensor capacitors into a voltage, the capacitance voltage conversion circuit comprising:
- a plurality of capacitance current conversion circuits disposed in respective correspondence with the sensor capacitors, each of the capacitance current conversion circuit configured to generate a detection current corresponding to a capacitance of a corresponding sensor capacitor;
a current average circuit configured to average detection currents, which are generated by the capacitance current conversion circuits, to generate an average current;
a plurality of current voltage conversion circuits disposed in respective correspondence with the sensor capacitors, each of the current voltage conversion circuit configured to convert a difference current between a corresponding detection current and the average current into a first output voltage, wherein in a standby mode, whether a user touches at least one of the sensor capacitors is determined on the basis of a difference current between the reference current and the average current;
a reference capacitor; and
a second capacitance current conversion circuit configured to generate a reference current corresponding to a capacitance of the reference capacitor.
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Abstract
A capacitance voltage conversion circuit, which converts respective capacitances of a plurality of sensor capacitors into voltages, includes: a plurality of capacitance current conversion circuits disposed in respective correspondence with the sensor capacitors, each capacitance current conversion circuit configured to generate a detection current corresponding to a capacitance of a corresponding sensor capacitor; a current average circuit configured to average a plurality of detection currents, which are respectively generated by the capacitance current conversion circuits, to generate an average current; and a plurality of current voltage conversion circuits disposed in respective correspondence with the sensor capacitors, each current voltage conversion circuit configured to convert a difference current between a corresponding detection current and the average current into a voltage.
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Citations
10 Claims
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1. A capacitance voltage conversion circuit which converts a capacitance of each of a plurality of sensor capacitors into a voltage, the capacitance voltage conversion circuit comprising:
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a plurality of capacitance current conversion circuits disposed in respective correspondence with the sensor capacitors, each of the capacitance current conversion circuit configured to generate a detection current corresponding to a capacitance of a corresponding sensor capacitor; a current average circuit configured to average detection currents, which are generated by the capacitance current conversion circuits, to generate an average current; a plurality of current voltage conversion circuits disposed in respective correspondence with the sensor capacitors, each of the current voltage conversion circuit configured to convert a difference current between a corresponding detection current and the average current into a first output voltage, wherein in a standby mode, whether a user touches at least one of the sensor capacitors is determined on the basis of a difference current between the reference current and the average current; a reference capacitor; and a second capacitance current conversion circuit configured to generate a reference current corresponding to a capacitance of the reference capacitor. - View Dependent Claims (2, 3, 4, 5)
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6. A capacitance voltage conversion circuit which converts a capacitance of each of a plurality of sensor capacitors into a voltage, the capacitance voltage conversion circuit comprising:
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a plurality of capacitance current conversion circuits disposed in respective correspondence with the sensor capacitors, each of the capacitance current conversion circuit configured to generate a detection current corresponding to a capacitance of a corresponding sensor capacitor; a current average circuit configured to average detection currents, which are generated by the capacitance current conversion circuits, to generate an average current; a plurality of current voltage conversion circuits disposed in respective correspondence with the sensor capacitors, each of the current voltage conversion circuit configured to convert a difference current between a corresponding detection current and the average current into a first output voltage, wherein in a standby mode, whether a user touches at least one of the sensor capacitors is determined on the basis of the average current; a reference capacitor; a second capacitance current conversion circuit configured to generate a reference current corresponding to a capacitance of the reference capacitor; and a second current voltage conversion circuit configured to convert a difference current between the reference current and the average current into a second output voltage, wherein the current average circuit averages the reference current and the detection currents which are respectively generated by the plurality of capacitance current conversion circuits, thereby generating the average current. - View Dependent Claims (7, 8, 9, 10)
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Specification