Device for a hardness measuring instrument

A non-destructive microhardness measuring instrument comprising

• a housing,
• a bar device having an end portion and pivotable about a pivot center,
• a test body supported on said end portion,
• a measuring device, which works on the basis of measuring the thickness of micro-thin layers, including a probe fixed to the housing and means defining a reference plane for measuring the distance to the probe fixed to the test body,
• an energizing means acting on said bar device having a first part rigid with said housing and a second part rigid with said bar device,
• a geometric first longitudinal axis passing through the center of said probe and the center of said test body,
• and the improvement wherein:
• (a) said first part of said energizing means rigid with said housing comprises a cylindrical electromagnetic coil having a geometric second longitudinal axis parallel with said geometric first longitudinal axis,
• (b) said coil has an opening for a carrier rod parallel with said geometric second longitudinal axis,
• (c) substantially coaxial with said geometric second longitudinal axis, said second part of said energizing means comprises said carrier rod which is rigid in its longitudinal direction relative to said end portion of said bar device and which is connected in entraining fashion to said bar device,
• (d) said carrier rod carries an upper magnet carrier above said coil and a lower magnet carrier below said coil,
• (e) fixed to each of said magnet carriers are a plurality of rigid permanent magnets each having one pole that points axially in the same direction, and
• (f) the travel of said carrier rod amounts to a few millimeters.