Patent ID: 7522155

Claim:
A trackball device comprising: a sphere including magnetic material; a support rotatably supporting said sphere, said support including first, second and third supporting members that are non-rotatable with respect to said sphere and are arranged in contact with said sphere at respectively spaced apart locations; a rotation detector provided separately from said support and configured to detect rotation of said sphere and output a signal indicating rotation of said sphere; a controller operably coupled to said rotation detector and being configured to generate a specific output signal responsive to the signal from said rotation detector indicating rotation of said sphere; and an informer including an electromagnet; wherein said sphere is disposed in a magnetic flux circuit generated by said electromagnet such that magnetic flux of said magnetic flux circuit goes from said electromagnet through said first supporting member, said sphere, and said second supporting member, and returns to said electromagnet, with said sphere being located in said magnetic flux circuit between said first and second supporting members; and wherein said informer is operable to change a friction force of said sphere with respect to said support by causing said electromagnet to generate a magnetic attractive force to attract said sphere to said first and second supporting members based on said specific output signal from said controller.