Method for manufacturing magnetic sensor, magnet array used in the method, and method for manufacturing the magnet array

A magnet array comprising a plurality of permanent magnets and a thin-plate yoke made of a magnetic material, each permanent magnet having a shape of a substantially rectangular parallelepiped, the rectangular parallelepiped having a cross section in a substantially square shape taken perpendicular to its axis, and each permanent magnet having magnetic poles generated on its corresponding opposite end surfaces having the substantially square shape perpendicular to the axis;

• the plurality of permanent magnets being arranged in such a manner that a centroid of each of the substantially square end surfaces thereof coincides with a lattice point of a tetragonal lattice, that the permanent magnets arranged on the same lattice line of the tetragonal lattice are such that one side of the end surface of a certain permanent magnet is substantially aligned with one side of the end surface of another permanent magnet, that the end surfaces of the plurality of permanent magnets are present substantially on the same plane, and that magnetic poles generated on the end surfaces of two adjacent, closest permanent magnets differ in polarity;
• and
• the yoke having a plurality of through holes arranged in substantially the same manner as the arranged permanent magnets, each through hole comprising a square portion having a shape substantially identical with the substantially square shape of the cross section of the permanent magnet, and rectangular portions each being formed along a central portion of a side of the square portion and having the central portion as its long side;
• the plurality of permanent magnets being inserted through the corresponding square portions of the plurality of through holes;
• and a plane in which the end surfaces of the plurality of permanent magnets are present is located between an upper surface and a lower surface of the yoke.

A method for manufacturing a magnet array comprising an array substrate formed of a thin plate, a plurality of permanent magnets arrayed on the array substrate, and a yoke disposed at upper portions of the plurality of permanent magnets and formed of a thin plate of a magnetic material, the method comprising the steps of:

• preparing the array substrate by means of forming a plurality of grooves in the thin plate in a predetermined tetragonal lattice array, each of the grooves having a predetermined depth and a square shape substantially identical in shape with an end face of the permanent magnet;
• preparing the yoke by means of forming a plurality of through holes in the thin plate of the magnetic material in the predetermined tetragonal lattice array, each of the through holes comprising a square portion having a square shape substantially identical in shape with the groove of the array substrate and rectangular portions each being formed along a central portion of a side of the square portion and having the central portion as its long side;
• arranging each of spacers on the array substrate between two adjacent parallel lines of the grooves;
• placing the yoke on the spacers in such a manner that, as viewed in plane, the plurality of grooves of the array substrate are aligned with the corresponding through holes of the yoke;
• inserting the plurality of permanent magnets each having a shape of a substantially rectangular parallelepiped, the rectangular parallelepiped having a cross section in a square shape taken perpendicular to its axis, the square shape being substantially identical in shape with the groove of the array substrate and with the square portion of the through hole of the yoke, each permanent magnet having magnetic poles generated on its corresponding opposite end surfaces having the square shape, into the corresponding grooves of the array substrate through the corresponding through holes of the yoke in such a manner that lower end surfaces of the permanent magnets abut corresponding bottom surfaces of the grooves;
• raising the yoke until a plane in which upper end surfaces of the permanent magnets are present is positioned between upper and lower surfaces of the yoke;
• and
• removing the spacers.