US Patent 8488292 Magnetic field generating means

A magnetic-field generating device includes at least one magnetic-field generator configured to generate a magnetic field so as to provide at least one magnetic gap for receiving objects upon which the magnetic field acts. At least one magnetic-field measuring device is disposed within a measuring-device receiving region outside of the magnetic gap. The at least one magnetic-field measuring device is configured to provide at least one measurement signal useable as an input signal for controlling the at least one magnetic-field generator.