Patent ID: 7679610

Claim:
A liquid crystal display (LCD) device, comprising: an external optical path for a probe light signal to traverse across a touchscreen surface, the external optical path comprising: a first reflective element disposed at the periphery of the touchscreen surface along a first edge of the touch touchscreen surface; a probe light source configured to transmit the probe light signal to the first reflective element, a second reflective element disposed at the periphery of the touchscreen surface along an opposite edge of the touchscreen surface to the first edge, wherein the first reflective element is configured to reflect the probe light signal from the probe light source across the touchscreen surface to the second reflective element and the second reflective element being configured to reflect the probe light signal from the first reflective element to a probe light sensing device; a probe light sensing device for detecting user contact with the touchscreen surface by sensing interruptions in the probe light signal traversing the external optical path; and a liquid crystal (LC) layer disposed behind a touchscreen surface, the LC layer being configured to: set a first and a second peripheral portion to a state of opacity, create a translucent opening in a first peripheral portion of the LC layer through which the probe light signal is transmitted from the probe light source to a first reflective element, create a translucent opening in a second peripheral portion of the LC layer through which the probe light signal is reflected by the second reflective element to the probe light sensing device, and scan the translucent openings through the first and second peripheral portions such that a location coordinate of the user contact is determined based on scan locations of the translucent openings by the probe light sensing device.