US Patent 8416217 Light-based finger gesture user interface

A light-based finger gesture user interface for an electronic device including a housing for an electronic device, a display mounted in the housing, a cavity, separated from the display, penetrating two opposite sides of the housing, a detector mounted in the housing operative to detect an object inserted in the cavity, and a processor connected to the detector and to the display for causing the display to render a visual representation in response to output from the detector.