US Patent 7843773 Contents playback apparatus, control method, and electronic device

A contents playback apparatus includes a tubular casing, a contents playback unit disposed in the casing, an operation element rotatably disposed around the casing and axially movably disposed on the casing, a magnet disposed on the operation element, a plurality of Hall devices disposed in the casing for detecting a density of magnetic fluxes from the magnet in a contactless fashion, and a controller for determining a position of the operation element based on the density of magnetic fluxes detected by the Hall devices upon movement of the operation element, and controlling the contents playback unit to play back contents depending on the determined position of the operation element.