Hall effect sensor for detecting an induced image magnet in a smooth material

The method of measuring the magnetic permeability of a magnetic material having a surface, the method comprising the steps of:

• positioning a permanent magnet in the vicinity of stationary, smooth surface magnetic material, the axis of said permanent magnet being positioned at an acute angle f with respect to said surface of said magnetic material such that the magnetic moment induced in said stationary magnetic material produces an image magnet in said material;
• and
• positioning a first Hall effect magnetic field sensor having only a single axis of sensitivity along said axis of said permanent magnet proximate said surface of said magnetic material, said magnetic field sensor having its axis of sensitivity perpendicular to said axis of said permanent magnet so as to detect the field produced by said induced image magnet in said material.

Apparatus for measuring a magnetization field induced in a stationary, smooth surface magnetic material, said apparatus comprising:

• a permanent magnet positioned in a vicinity of the surface of said stationary magnetic material, said permanent magnet having its axis oriented at an acute angle f with respect to said surface of said magnetic material such that the magnetic moment induced in said stationary magnetic material produces an image magnet in said material;
• and
• a first Hall effect magnetic field sensor having only a single axis of sensitivity positioned proximate said surface of said magnetic material, said first magnetic field sensor having its axis of sensitivity oriented to be perpendicular to the magnetic field from said permanent magnet, said first magnetic field sensor positioned on said axis of said magnetic moment so as to detect the field produced by said induced image magnet in said material.

The apparatus of 13 further including a second Hall effect magnetic field sensor having only a single axis of symmetry, said second magnetic field sensor being positioned proximate said surface of said magnetic material, said second magnetic field sensor having its axis of sensitivity oriented perpendicular to said axis of said permanent magnet.

The apparatus of 14 wherein said axis of sensitivity of said first magnetic field sensor and said axis of sensitivity of said second magnetic field sensor are parallel.

Apparatus for measuring the velocity of an electrically conductive nonmagnetic, smooth surface moving material, said apparatus comprising:

• a permanent magnet having an axis oriented at an acute angle of f with respect to an electrically conductive nonmagnetic, smooth surface moving material;
• and
• a first Hall effect magnetic field sensor having only a single axis of sensitivity positioned proximate said electrically conductive material and having its axis of sensitivity perpendicular to said axis of said permanent magnet, said first magnetic field sensor detecting a magnetic field generated by eddy currents induced in said electrically conductive material by said field from said permanent magnet wherein the signal derived from the induced eddy current fields is proportional to the velocity of said moving material.