Positioning table device including correction of energization electric current to selected coils of a permanent magnet of a drive device

A positioning table device comprising:

• a table;
• guiding means for guiding movement of said table in a predetermined direction;
• driving means for producing a thrust for moving said table along the predetermined direction in association with said guiding means, said driving means including a permanent magnet provided on said table and a plurality of coils provided along the predetermined direction, said plurality of coils being movable to be opposed to said permanent magnet sequentially with the movement of said table guided by said guiding means;
• position detecting means for detecting a position of said table in the predetermined direction;
• designating means for designating an energization electric current in accordance with an output of said position detecting means;
• coil selecting means for selecting a coil, of said coils to be energized, in accordance with the position of said table in the predetermined direction;
• storing means for memorizing a correction coefficient for correcting the energization electric current designated by said designating means, in accordance with the position of said table in the predetermined direction;
• correcting means for correcting the energization electric current designated by said designating means on the basis of the correction coefficient memorized in said storing means, so as to compensate for a thrust ripple of said driving means produced as coils opposed to said permanent magnet are changed with the movement of said table;
• current supplying means for energizing the coil selected by said coil selecting means, in accordance with the energization electric current corrected by said correcting means;
• measuring means for measuring, during constant speed motion of said table and at intervals of movement of said table through a predetermined pitch, a sum of absolute values of the energization electric currents applied to said coils from said current supplying means;
• and
• control means for causing said storing means to memorize a value determined on the basis of the measurements by said measuring means, as the correction coefficient.