A liquid crystal display (LCD) device (5) having an integrated touchscreen includes a probe light source (80) behind the liquid crystal (LC) layer (20) for transmitting a probe signal. The device further includes a probe light sensor (90) behind the LC layer for sensing the probe signal. An external optical path is provided whereby the probe signal traverses from the probe light source, across the touchscreen surface (1), and toward the probe light sensor. By sensing interruptions in the probe signal traversing the external optical path, using the probe light sensor, the LCD device is capable of detecting user contact with the touchscreen surface.