Capacitance detection device, capacitance detection method, and input device

A capacitance detection device for detecting a capacitance between a detection electrode and an object approaching the detection electrode, the capacitance detection device comprising:

• an AC voltage output unit configured to output a first AC voltage and a second AC voltage, the first AC voltage being supplied to a shield electrode disposed in a vicinity of the detection electrode, and the second AC voltage having a frequency and a phase which are substantially the same as that of the first AC voltage and having an amplitude smaller than that of the first AC voltage such that there is an amplitude difference between the first AC voltage and the second AC voltage;
• a detection signal generation unit having a first node connected to the detection electrode, configured to supply a charge to the detection electrode from the first node such that a voltage of the first node approaches the second AC voltage, and to generate an AC detection signal in accordance with the charge supplied to the detection electrode;
• a calculation unit configured to calculate a detection value of the capacitance based on the AC detection signal;
• and
• a correction unit configured to correct an error in the detection value due to a change in a shield capacitance which is a parasitic capacitance between the shield electrode and the detection electrode,
• wherein the correction unit is further configured to have a correction mode which is repeatedly performed, and in the correction mode, the correction unit controls the AC voltage output unit to change the amplitude difference between the first and second AC voltages, which causes a change in the detection value, and to obtain a correction value corresponding to the change in the detection value caused by a change in the difference, and
• wherein the correction unit corrects, in a normal mode, the detection value in accordance with a change in the correction value obtained in the correction mode.