| 摘要 |
A linear motor, suitable to drive a photolithography positioning stage, incorporates a magnet array having transverse magnets and wedge magnets. The transverse magnets are spaced at regular intervals along a direction parallel with their magnetic polarities. Each transverse magnet is linked by a closed magnetic flux circuit with two adjacent wedge magnets having magnetic polarities oriented at an angle relative to the transverse magnet polarities. The local flux direction is substantially parallel to the magnetic polarity within each magnet, effectively enhancing magnetic flux density. Magnetic flux circuits are completed directly through the magnets and not through side rails, allowing selection of stronger, lighter-weight nonmagnetic side rail material. Wedge magnets with rectangular and trapezoidal cross-sectional shapes are described. Alternative array configurations contain two rows of complementary transverse and wedge magnets spaced on opposite sides of a coil array. Paired transverse magnets spaced across from one another have opposite polarities.
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