Input device

1 . An input device comprising:

a detection electrode;

a drive electrode facing the detection electrode;

a power supply configured to apply an alternating current drive voltage to the drive electrode;

a detector configured to detect an output of the detection electrode;

a capacitor disposed in series between the drive electrode and the power supply so that the alternating current drive voltage is applicable to the drive electrode; and

an elastic member that is deformable by a pressing operation performed by an operation body on an operation surface, wherein

the drive electrode is disposed on a portion closer to the operation surface relative to the elastic member, and

the detection electrode is disposed on a portion opposite to the operation surface relative to the elastic member.

2 . The input device according to claim 1 , wherein

the capacitor includes a first electrode and a second electrode facing the first electrode,

the first electrode is connected to the power supply, and

the second electrode is connected to the drive electrode.

3 . The input device according to claim 1 , further comprising:

a substrate that is disposed on a portion opposite to the operation surface relative to the elastic member, wherein

the capacitor includes a first electrode and a second electrode facing the first electrode,

the detection electrode and the first electrode are disposed on the substrate, and

the drive electrode has an extending portion extending toward and connected to the second electrode.

4 . The input device according to claim 1 , further comprising:

a skin that covers the elastic member, wherein

the drive electrode has an extending portion, and

the drive electrode and the extending portion are disposed on the skin.

5 . The input device according to claim 4 , wherein

the operation surface is a portion of an outer surface of the skin that overlaps the drive electrode.

6 . The input device according to claim 1 , further comprising:

a determination section configured to determine, when an output of the detector falls to a first threshold value or below, that a touching operation has been performed by an operation body.

7 . The input device according to claim 6 , wherein

the determination section is further configured to determine, when the output of the detector falls to a second threshold value or below that is greater than the first threshold value, that an approaching operation has been performed by the operation body.

8 . The input device according to claim 6 , wherein

the determination section is further configured to determine that a pressing operation has been performed by the operation body when the output of the detector changes from a value smaller than the first threshold value to a value equal to or greater than a third threshold value that is greater than a baseline value of the output of the detector after determining that the touching operation has been performed.

9 . The input device according to claim 1 , further comprising:

an elastic member that is deformable by a pressing operation performed by an operation body on an operation surface; and

a substrate that is disposed on a portion opposite to the operation surface relative to the elastic member, wherein

the detection electrode is disposed on the substrate,

the capacitor includes a first electrode disposed on the substrate and a second electrode facing the first electrode, and

the drive electrode has an extending portion extending toward and connected to the second electrode.

10 . An input device comprising:

a detection electrode;

a drive electrode facing the detection electrode;

a power supply configured to apply an alternating current drive voltage to the drive electrode;

a detector configured to detect an output of the detection electrode;

a capacitor disposed in series between the drive electrode and the power supply so that the alternating current drive voltage is applicable to the drive electrode;

an elastic member that is deformable by a pressing operation performed by an operation body on an operation surface; and

a substrate that is disposed on a portion opposite to the operation surface relative to the elastic member, wherein

the detection electrode is disposed on the substrate,

the capacitor includes a first electrode disposed on the substrate and a second electrode facing the first electrode, and

the drive electrode has an extending portion extending toward and connected to the second electrode.

11 . The input device according to claim 10 , further comprising:

a skin that covers the elastic member, wherein

the drive electrode and the extending portion are disposed on the skin.

12 . The input device according to claim 11 , wherein

the operation surface is a portion of an outer surface of the skin that overlaps the drive electrode.

13 . The input device according to claim 10 , further comprising:

a determination section configured to determine, when an output of the detector falls to a first threshold value or below, that a touching operation has been performed by an operation body.

14 . The input device according to claim 13 , wherein

the determination section is further configured to determine, when the output of the detector falls to a second threshold value or below that is greater than the first threshold value, that an approaching operation has been performed by the operation body.

15 . The input device according to claim 13 , wherein

the determination section is further configured to determine that a pressing operation has been performed by the operation body when the output of the detector changes from a value smaller than the first threshold value to a value equal to or greater than a third threshold value that is greater than a baseline value of the output of the detector after determining that the touching operation has been performed.