Input apparatus for a data processing system. An input apparatus, for example a mouse or a track ball, comprises a member which is rotatable by manipulation by a user. The rotation causes a change of a magnetic field, which change is detected by a detector. The member in the apparatus in accordance...http://www.google.de/patents/US5831553?utm_source=gb-gplus-sharePatent US5831553 - Input apparatus for a data processing system
