Embedded touch screen

1. An embedded touch screen, comprising:

a first substrate;

a second substrate comprising, on a front surface thereof:

a plurality of scanning signal lines extending in a first direction;

a plurality of video signal lines extending in a second direction;

a plurality of switching elements, each electrically connected to one of the plurality of scanning signal lines and one of the plurality of video signal lines;

a plurality of pixels sectioned by the plurality of scanning signal lines and the plurality of video signal lines in matrix being arranged in an image region and each comprising a pixel electrode connected to corresponding one of the plurality of video signal lines via one of the plurality of the switching elements connected to corresponding one of the plurality of scanning signal lines; and

a common electrode;

a liquid crystal layer sandwiched between the first substrate and the second substrate;

an application circuit for applying an alternating signal;

a detection circuit for detecting a signal excited on a plurality of detection electrodes; and

a scanning circuit for scanning, during application by the application circuit and detection by the detection circuit, at least one of a plurality of excitation electrodes and the plurality of detection electrodes at least in the second direction,

wherein each of the plurality of excitation electrodes extend along the second direction, each of the plurality of detection electrodes extend along the second direction, and each of the plurality of excitation electrodes and each of the plurality of detection electrodes are alternatively arranged and adjacent to each other in the first direction;

wherein the plurality of excitation electrodes define the pixel electrodes and the plurality of detection electrodes define a video signal shielding electrode provided in parallel to the each of the plurality of video signal lines in an overlapping manner,

wherein the scanning circuit provides on-voltage with a plurality of switching elements for each scanning unit that is time-divided, the scanning unit includes a number of scanning signal lines from among the plurality of scanning signal lines, and

wherein a contact position in the first direction is detected based on a position at which a change of the signal is detected, and the contact position in the second direction is detected based on a timing at which the change of the signal is detected.

2. The embedded touch screen according to claim 1 , wherein, during the application by the application circuit and the detection by the detection circuit, the detection circuit detects the signals excited on the plurality of detection electrodes through the scanning in the second direction.

3. The embedded touch screen according to claim 1 , wherein a pitch between one of the plurality of excitation electrodes and an adjacent one of the plurality of detection electrodes is larger than a distance between a front surface of the first substrate and the front surface of the second substrate.

4. The embedded touch screen according to claim 1 , wherein the application circuit applies an alternating signal, which has a phase reversed by 180° with respect to an alternating signal applied to one of the plurality of excitation electrodes adjacent to a corresponding one of the plurality of detection electrodes, to another of the plurality of excitation electrodes adjacent to the corresponding one of the plurality of detection electrodes.

5. The embedded touch screen according to claim 1 , wherein the detection circuit obtains a difference between the signal excited by the corresponding one of the plurality of detection electrodes and an alternating signal in the same phase as the alternating signal applied by the application circuit.

6. The embedded touch screen according to claim 1 , further comprising a video display circuit for writing a video signal into the pixel electrode,

wherein the video signal is updated in a period corresponding to a frame, the frame including:

a writing period in which the video display circuit writes the video signal; and

a detection period in which the application by the application circuit and the detection by the detection circuit are performed, and

wherein, during the detection period, one of causing the pixel electrode to hold a signal for black display and turning OFF a backlight unit is performed.

7. The embedded touch screen according to claim 1 , further comprising a video display circuit for writing a video signal into the pixel electrode,

wherein the video signal is updated in a period corresponding to a frame, the frame including:

a writing period in which the video display circuit writes the video signal; and

a detection period in which the application by the application circuit and the detection by the detection circuit are performed, and

wherein, during the detection period, the pixel electrode holds the video signal, and one of the alternating signal applied by the application circuit and a signal excited by the alternating signal is superimposed to the pixel electrode.