| 摘要 |
<p>An oval-shaped sensor 16 is used to measure the material content of the outer ring of a bimetallic coin 2, the coil being mounted on a ferrite whose inner diameter is wider than the core of the bimetallic coin so that eddy currents are confined to the outer ring. A thickness sensor 18 may be mounted within the oval sensor, and a separate coil 14 is used for measuring the material content of the core. The thickness sensor may also be used for measuring material down to a different depth, for validating clad coins. The oval sensor is used also for diameter measurement.</p> |
