Patent ID: 7202584

Claim:
A position-control stage system; comprising a bed, a turntable supported for rotation on the bed through a rolling-contact bearing, and a motor forcing the turntable relatively to the bed in a circular direction; wherein the motor includes an armature assembly on a primary side, which is composed of armature windings made of coreless annular coils wound in a form of a flat configuration, the armature windings lying on the bed in circular direction in a form of a desired circular pattern; wherein the motor includes a field magnet on a secondary side, which is composed of magnet segments, which are juxtaposed on the turntable in opposition to the armature windings in such a array that they alternate in polarity circularly in circumferential direction along a desired circular pattern; and wherein the bed doubles as a coil yoke while the turntable doubles as a magnet yoke; wherein the rolling-contact bearing is comprised of an inner race, an outer race arranged around the inner race, and more than one rolling element of rollers interposed between the inner and outer races in such a way any two adjacent rollers are oppositely inclined with their own axes intersecting alternately one another; wherein the inner race is fixed in abutment to the bed only by a screw through the bed and threaded in a first threaded hole in the inner race and the outer race is fixed in abutment to the turntable only by a screw through the turntable and threaded in a second threaded hole in the outer race; wherein the armature assembly of the armature windings on the bed fits into an annular recess, which is made in a top side of the bed with an inner circumference of the recess spaced apart from an outside circular surface of the outer race of the bearing wherein there being no intervening structure between the inner circumference and the outside circular surface, the space between the inner circumference and the outside circular surface can be reduced to the point that the armature windings are as close as desirable to or in contact with the outer race; and wherein the armature windings and the magnet segments are both made in a form of a trapezoid where a radially inside base is smaller than a radially outside base while circularly opposing diagonals focus equally on a common center of turning, so that the armature windings and the magnet segment, respectively, are allowed lying in close juxtaposition in such a relation that the opposing diagonals of any two adjoining companions come into the closest approach to one another.