Patent ID: 7230231

Claim:
A device comprising: a housing with a housing wall made of a plastic which, in normal lighting, precludes optical perception of an underlying dark surface, the housing wall having a uniformly smooth outer surface without recesses, clearances, or apertures and an inner surface, and a display unit with at least one light-emitting element which transmits radiation that lies in a range of 400–700 nm and which is located inside the housing, beneath the inner surface of the housing wall, wherein the housing wall has at least one recess or a reduced wall thickness, but no apertures, in an area of the light-emitting element, wherein the light intensity of the at least one light-emitting element is adjusted in such a way that, in the emitting state, lighting other than said normal lighting is produced and the at least one light-emitting element is optically perceptible in a localizable manner through the housing wall only in the area of the light-emitting element, and wherein the housing wall has said at least one recess and at least one further recess, into which a detector is let, which makes it possible to detect the light by the light-emitting element through the housing wall onto an item and the light reflected by the item through the housing wall.