Embodiments are disclosed herein related to the avoidance of undesirable optical effects in a liquid crystal display used with a touch-sensitive display input device. For example, one embodiment provides a user interface comprising a body, a light source disposed within the body, and a liquid crystal display configured to create an image displayable on one or more display surfaces coupled to the body. The user interface device further includes a light delivery system positioned optically between the light source and the liquid crystal display to deliver light produced by the light source to the liquid crystal display. The light delivery system comprises a light exit surface spaced from the liquid crystal display to form a gap positioned between the light exit surface of the light delivery system and the liquid crystal display.