Abstract: Retractable wire systems for mobile devices include a wire and a winding mechanism within a housing for the mobile device. The wire is configured to provide electrical communication between the mobile device and an accessory for the mobile device. The winding mechanism is configured to releasably wind the wire, the wire being selectively moveable between a wound position and an unwound position. In some examples, the housing is integral to a rear wall of the mobile device. In some further examples, the housing is a mobile device cover releasably attachable to an outer surface of the mobile device.

Abstract: A perceptible signal is provided, which is a repetition of a time-limited perceptible signal sequence. The time-limited perceptible signal sequence comprises at least two sets of signal elements, each of which constituting a general trend in signal characteristics as well as interval. The general trend in the end of one set agrees essentially with the general trend in the beginning of another set within the time-limited signal sequence. When the sequences are repeated, a transfer between sets of signal elements becomes essentially unnoticeable, creating perceived signal sequences extending over several sequence intervals. In one aspect of the present invention, a mammal can be exposed for such a perceptible signal. In another aspect of the present invention, a memory device has a representation of such perceptible signals stored for enabling an easy retrieval of the perceptible signal.