| 摘要 |
A stator portion of a linear motor includes a U-phase coil portion ( 10 U), a V-phase coil portion ( 10 V), and a W-phase coil portion ( 10 W) through which currents with phases different by 120 degrees from one another flow. Each coil portion has pairs of a first coil wound clockwise and a second coil wound counterclockwise. The pairs of coils adjoin to each other in the moving direction and are connected in series and arrayed in the moving direction. When the extension length from the first coil to the second coil is 360 degrees, the V-phase coil portion overlaps with and is shifted from the U-phase coil portion by 120 degrees, and the W-phase coil portion overlaps with and is shifted from the V-phase coil portion by 120 degrees with respect to the moving direction. A magnet portion ( 30 ) is movably combined with the U-phase, V-phase, and W-phase coil portions. The length of the magnet portion in the moving direction is less than a half of the wavelength of the magnetic flux generated with the coils. On a movable portion, a Hall element ( 40 ) is mounted at the position away from the center of the magnet portion by an integral multiple of a half of the wavelength of the magnetic flux generated with the coils. Depending on the output from the Hall element, the amplitude or phase of the current fed to each coil portion is controlled.
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