Display device

1. A display device comprising:

an array substrate; and

a counter substrate,

wherein: on the array substrate, a TFT, a pixel electrode, an antenna coil, at least two external connection terminals, and a capacitor are provided;

two ends of the antenna coil are respectively connected to the at least two external connection terminals;

the TFT includes a switching TFT;

a set of the switching TFT and the capacitor or a plurality of sets of the switching TFT and the capacitor is provided; and

to the antenna coil, the set of the switching TFT and the capacitor or the plurality of sets of the switching TFT and the capacitor is connected, and

wherein the two ends of the antenna coil include a frequency measurement terminal different from the at least two external connection terminals.

2. The display device according to claim 1 ,

wherein at least one set of the switching TFT and the capacitor is connected to the antenna coil in a display region of the display device.

3. The display device according to claim 1 ,

wherein a source and a drain of the switching TFT are connected in a loop of the antenna coil.

4. The display device according to claim 1 ,

wherein the pixel electrode is configured of a metal.

5. The display device according to claim 1 ,

wherein: the TFT further includes a buffer TFT;

the TFT has a buffer circuit formed of the buffer TFT; and

the buffer circuit is connected to a gate electrode of the switching TFT.

6. The display device according to claim 5 ,

wherein at least a part of the switching TFT and at least a part of the buffer TFT overlap at least one of the pixel electrode and the antenna coil.

7. A display device comprising:

a first substrate;

on the first substrate, a plurality of display elements;

a plurality of first transistors individually connected to the plurality of display elements;

a first electrode in a spiral form;

a first terminal connected to a first end of the first electrode;

a second terminal connected to a second end of the first electrode; and

a plurality of second transistors and a plurality of capacitors connected to the first end or the second end in a manner that capacitance values of the plurality of second transistors and the plurality of capacitors are changeable,

wherein: the plurality of display elements each has a pixel electrode; and

the first electrode is disposed between the pixel electrode and the first substrate in a manner that at least a part of the first electrode overlaps the pixel electrode and the first substrate.

8. The display device according to claim 7 ,

wherein at least one of the plurality of second transistors is disposed between the pixel electrode and the first substrate.

9. A display device comprising:

a first substrate;

on the first substrate, a plurality of display elements;

a plurality of first transistors individually connected to the plurality of display elements;

a first electrode in a spiral form;

a first terminal connected to a first end of the first electrode;

a second terminal connected to a second end of the first electrode; and

a plurality of second transistors and a plurality of capacitors connected to the first end or the second end in a manner that capacitance values of the plurality of second transistors and the plurality of capacitors are changeable,

wherein: the display device has a controller; and

the controller is configured to drive the first terminal at a predetermined frequency, measure a frequency of the second terminal, and switch between connected states of the plurality of second transistors in accordance with a measured frequency.

10. The display device according to claim 7 ,

wherein: the display device has a controller; and

the controller is configured to drive the first terminal at a predetermined frequency, measure a frequency of the second terminal, and switch between connected states of the plurality of second transistors in accordance with a measured frequency.

11. The display device according to claim 8 ,

wherein: the display device has a controller; and

the controller is configured to drive the first terminal at a predetermined frequency, measure a frequency of the second terminal, and switch between connected states of the plurality of second transistors in accordance with a measured frequency.

12. A display device comprising:

a first substrate;

a plurality of display elements each having a pixel electrode;

a first electrode in a spiral form disposed between the pixel electrode and the first substrate in a manner that at least a part of the first electrode overlaps the pixel electrode and the first substrate;

a first terminal connected to a first end of the first electrode; and

a second terminal connected to a second end of the first electrode.

13. The display device according to claim 12 , further comprising:

a plurality of transistors and a plurality of capacitors connected to the first end or the second end of the first electrode.

14. The display device according to claim 13 ,

wherein the plurality of transistors and the plurality of capacitors are connected to the first end or the second end in a manner that capacitance values of the plurality of second transistors and the plurality of capacitors are changeable.

15. The display device according to claim 13 ,

wherein at least one of the plurality of transistors is disposed between the pixel electrode and the first substrate.

16. The display device according to claim 13 ,

wherein: the display device has a controller; and

the controller is configured to drive the first terminal at a predetermined frequency, measure a frequency of the second terminal, and switch between connected states of the plurality of second transistors in accordance with a measured frequency.

17. The display device according to claim 14 ,

wherein: the display device has a controller; and

the controller is configured to drive the first terminal at a predetermined frequency, measure a frequency of the second terminal, and switch between connected states of the plurality of second transistors in accordance with a measured frequency.