Wedge magnet array for linear motor
First Claim
1. An apparatus comprising a magnet array suitable for a linear motor, having a first array segment including:
- a transverse magnet having a magnetic polarity oriented substantially parallel to a first direction; and
a wedge magnet having a magnetic polarity oriented at an angle to said first direction;
wherein a closed magnetic flux circuit passes through said transverse magnet and said wedge magnet, having a direction such that the magnetic polarities of said transverse magnet and said wedge magnet are each aligned substantially parallel with the respective local directions of said magnetic flux circuit.
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Accused Products
Abstract
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.
115 Citations
36 Claims
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1. An apparatus comprising a magnet array suitable for a linear motor, having a first array segment including:
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a transverse magnet having a magnetic polarity oriented substantially parallel to a first direction; and a wedge magnet having a magnetic polarity oriented at an angle to said first direction; wherein a closed magnetic flux circuit passes through said transverse magnet and said wedge magnet, having a direction such that the magnetic polarities of said transverse magnet and said wedge magnet are each aligned substantially parallel with the respective local directions of said magnetic flux circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of making a magnet array suitable for a linear motor, comprising the acts of:
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assembling an array segment including a transverse magnet and a wedge magnet adjacent one another along a first direction, such that the magnetic polarity of said transverse magnet is oriented substantially parallel to said first direction and the magnetic polarity of said wedge magnet is oriented at an angle to said first direction; wherein a closed magnetic flux circuit passes through said transverse magnet and said wedge magnet, having a direction such that the magnetic polarities of said transverse magnet and said wedge magnet are each aligned substantially parallel with the respective local directions of said magnetic flux circuit. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A method of operating a linear motor, comprising:
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providing a magnet array, said magnet array comprising an array segment including a transverse magnet and a wedge magnet adjacent one another along a first direction, such that the magnetic polarity of said transverse magnet is oriented substantially parallel to said first direction and the magnetic polarity of said wedge magnet is oriented at an angle to said first direction, wherein a closed magnetic flux circuit passes through said transverse magnet and said wedge magnet, having a direction such that the magnetic polarities of said transverse magnet and said wedge magnet are each aligned substantially parallel with the respective local directions of said magnetic flux circuit; providing a linear coil array cooperating with said magnet array; energizing said coil array by applying electric current to said coil array, thereby generating an electromagnetic force on said coil array in cooperation with said magnet array. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. A photolithographic apparatus comprising:
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a projection system; a stage for carrying an object, the object being one of a mask carrying a pattern to be projected by the projection system or a workpiece to be imaged by said projection system; and a linear motor coupled to said stage for driving the stage, said linear motor including; a coil array; and a magnet array cooperating with said coil array and comprising an array segment including a transverse magnet having a magnetic polarity oriented substantially parallel to a first direction, said array segment further comprising a wedge magnet having a magnetic polarity oriented at an angle to said first direction; wherein a closed magnetic flux circuit passes through said transverse magnet and said wedge magnet, having a direction such that the magnetic polarities of said transverse magnet and said wedge magnet are each aligned substantially parallel with the respective local directions of said magnetic flux circuit. - View Dependent Claims (31, 32, 33, 34, 35, 36)
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Specification