Apple Inc.
Disappearing button or slider

Abstract:

An input device is operable to detect input. The input device is a deflection based capacitive sensing input device. Deflection of a metal frame of the input device causes a change in capacitance that is used to control a function of an electrical device. The input device appears invisible because it is made of the same material as the housing it is contained in. Invisible backlit holes may make the input selectively visible or invisible to the user.