Display unit with touch detection function and electronic unit

1. A display unit comprising:

a first substrate;

a second substrate opposed to the first substrate in a vertical direction perpendicular to the first substrate;

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

drive electrodes;

pixel electrodes disposed between the drive electrodes and the liquid crystal layer, in the vertical direction;

pixel signal lines each connected to the pixel electrodes, the pixel signal lines being disposed under the drive electrodes in the vertical direction, and the pixel signal lines, the drive electrodes, and the pixel electrodes being sequentially arranged in the vertical direction on a liquid crystal side of the first substrate;

touch detection electrodes disposed on an upper surface side of the second substrate;

a source driver configured to apply a pixel signal to the pixel signal lines;

a touch detection circuit configured to detect a touch event based on a detection signal that is output from the touch detection electrodes during a touch detection period that is distinct from a display period during which the pixel signal is supplied to the pixel electrodes;

a switch configured to switch an electrical connection between the source driver and the pixel signal lines; and

a drive electrode driver configured to:

in the display period, sequentially apply an alternating current (AC) drive signal to the drive electrodes corresponding to a series of horizontal lines as a display drive object, and the liquid crystal layer being driven by applying a first voltage between the pixel electrodes and the drive electrodes, and

in the touch detection period, sequentially apply:

the AC drive signal, as a touch detection drive signal, selectively to a first subset of the drive electrodes, and

a direct current (DC) drive signal to a second subset of the drive electrodes that are mutually exclusive with the first subset of the drive electrodes,

wherein, in the touch detection period, the source driver applies a second voltage to the pixel signal lines at a predetermined level to maintain a respective potential of each of the pixel signal lines, and

wherein the touch event is detected based on the detection signal, such that the touch detection drive signal is transmitted to the touch detection electrodes through a first capacitance between the touch detection electrodes and the first subset of the drive electrodes, allowing the detection signal to change and to be output from the detection electrodes.

2. The display unit according to claim 1 , wherein the touch detection circuit has a detection switch allowing the detection signal to be transmitted, the detection switch being turned on immediately before the touch detection period, thereby applying a virtual short-circuit voltage to the touch detection electrodes.

3. The display unit according to claim 1 , wherein

the touch detection electrodes form a second capacitance with the pixel signal lines, and

the touch detection electrodes overlap the pixel signal lines in a perspective from the vertical direction.

4. The display unit according to claim 1 , wherein, in the touch detection period, the source driver applies the second voltage to the pixel signal lines at the predetermined level to maintain the respective potential of each of the pixel signal line, thereby reducing a second capacitance corresponding to a direct coupling between the touch detection electrodes and the pixel signal lines.