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 the detection currents, which are 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 of the 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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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
33 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 the detection currents, which are 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 of the current voltage conversion circuit configured to convert a difference current between a corresponding detection current and the average current into a voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 26, 27, 28, 29, 30, 31)
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13. 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 reset switches disposed in respective correspondence with the sensor capacitors, each of the reset switches configured to initialize an electric potential of a corresponding sensor capacitor; a plurality of integral capacitors disposed in respective correspondence with the sensor capacitors, an electric potential of one end of each integral capacitor being fixed; an initialization circuit configured to initialize respective voltages of the integral capacitors; a plurality of current mirror circuits disposed in respective correspondence with the sensor capacitors, each of the current mirror circuits configured to supply a current, which flows in a second transistor of an output side of each of the current mirror circuits, to a corresponding integral capacitor in a first direction, a first transistor of an input side of each of the current mirror circuits being connected to the corresponding sensor capacitor; and a current average circuit configured to generate an average current of a plurality of detection currents which respectively flow in the sensor capacitors, and supply the average current to the integral capacitors in a second direction. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. 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 integral capacitors disposed in respective correspondence with the sensor capacitors, an electric potential of one end of each of the integral capacitors being fixed; a plurality of reset switches disposed in respective correspondence with the sensor capacitors, each of the reset switches being connected to a corresponding sensor capacitor in parallel; a plurality of sensing switches disposed in respective correspondence with the sensor capacitors, one end of each of the sensing switches being connected to the corresponding sensor capacitor; a plurality of first transistors, being MOSFETs, disposed in respective correspondence with the sensor capacitors, each of the first transistors being disposed on a path of the corresponding sensing switch; a plurality of second transistors, being MOSFETs, disposed in respective correspondence with the sensor capacitors, a gate of each of the second transistors being connected to a gate of a corresponding first transistor, and a drain of each of the second transistors being connected to a corresponding integral capacitor; a plurality of fifth transistors, being MOSFETs, disposed in respective correspondence with the sensor capacitors, a gate of each of the fifth transistors being connected to a gate of the corresponding first transistor; a plurality of third transistors disposed on a path of a corresponding fifth transistor, in respective correspondence with the sensor capacitors; and a plurality of fourth transistors disposed in respective correspondence with the sensor capacitors, each of the fourth transistors being connected to a corresponding third transistor to form a current mirror circuit therewith, and a drain of each of the fourth transistors being connected to the corresponding integral capacitor. - View Dependent Claims (22, 23, 24, 25)
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32. A method of converting a capacitance of each of a plurality of sensor capacitors into a voltage, the method comprising:
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initializing an electric potential of each of the sensor capacitors; supplying a first current until each of the voltages reaches a predetermined level, in correspondence with each of the sensor capacitors; supplying a second current, which corresponds to a corresponding first current, to an integral capacitor, which is disposed in correspondence with each of the sensor capacitors, in a first direction, and supplying an average current of a plurality of second currents to each of the integral capacitors in a second direction; and outputting a voltage, generated in each of the integral capacitors, as a detection voltage which corresponds to a corresponding capacitance. - View Dependent Claims (33)
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Specification