Liquid crystal display device with built-in touch sensor, and drive method therefor

A drive method for a liquid crystal display device with a built-in touch sensor, the liquid crystal display device having a display period for performing image display and a sleep period for stopping image display, wherein

• the liquid crystal display device includes:
• a liquid crystal panel including a pixel electrode and a common electrode;
• a backlight configured to irradiate the liquid crystal panel with light;
• a display drive portion configured to perform image data write processing in which a desired voltage is applied to the pixel electrode in a state in which a constant voltage is applied to the common electrode;
• a backlight control portion configured to control a state of the backlight;
• and
• a sensor drive portion configured to perform position detection processing during both of the display period and the sleep period, the position detection processing being a process in which a position on the liquid crystal panel that has been touched is detected,
• the common electrode is used as an electrode for the position detection processing, and
• the drive method comprises:
• a display step in which, during the display period, the backlight control portion maintains the backlight in a light-up state and the display drive portion performs the image data write processing so that a voltage depending on a target display image is applied to the pixel electrode;
• a stopping step in which the backlight control portion maintains the backlight in a light-out state during the sleep period;
• and
• an image data write insertion step in which the display drive portion performs the image data write processing at least during a part of the sleep period.