Patent ID: 8112132

Claim:
A mobile device comprising: a cord having inner and outer sections; a retractor into which the cord is retracted for storage, the retractor including a fixture holding the inner section; a sensor adapted to generate a position data output related to the position of the fixture; a controller that receives the position data output from the sensor, and, in response, controls a function of the device; a portable audio device for providing an audio output signal, wherein the retractor comprises a reel for winding up the cord and spring means for biasing the reel to wind the cord onto the reel; the sensor comprises a rotary encoder that generates the position data output according to the rotational position of the reel, the cord comprises flexible conductors for transmitting the audio output signal, and further comprising an earpiece coupled to the outer section of the cord for projecting audible signals to a user in response to the audio output signal; the rotary encoder comprises at least one discontinuity provided in a circumferential surface on the reel and a Hall-effect sensor arranged with respect to the at least one discontinuity so as to enable each one of the at least one discontinuities to exert a characteristic magnetic influence upon the Hall-effect sensor during reel rotation; the reel further includes slip rings through which the audio output signal is transmitted and each one of the at least one rotor discontinuities further comprises a recessed area formed in one of the slip rings.