Mask Stage Linear Motor Structure for 3-DOF Precision Motion
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Solution Overview
Problem
Implementing a linear motor with high magnetic flux density and efficiency in a 3-DOF plane stage for mask stages is challenging due to strong magnetic attraction forces between the core and permanent magnets, hindering high-speed driving and precise position control.
Innovation Solution
A linear motor configuration with a magnetic core having protruding portions and a coil arrangement, combined with a magnet module of permanent magnets, allows for controlled magnetic attraction forces, enabling high-speed driving and precise position control in the X, Y, and θz directions using a pair of linear motors with adjustable thrust directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a linear motor with high magnetic flux density and efficiency is implemented in a 3-DOF plane stage, then driving speed and position control precision are improved, but strong magnetic attraction forces between the core and permanent magnets cause operational difficulties
Solution Approach 1:
The magnetic core is divided into multiple segments with protruding portions, allowing the permanent magnets to be positioned in the spaces between protrusions. This segmentation reduces the magnetic attraction force while maintaining the high magnetic flux density needed for high-speed driving.
Solution Approach 2:
The protruding portions of the magnetic core act as intermediaries that distribute and reduce the direct magnetic attraction between the core and permanent magnets, enabling high-speed operation without excessive magnetic forces.
2Measurement precision
If a linear motor with high magnetic flux density is used, then position control precision is improved, but the strong magnetic attraction forces hinder precise position control
Solution Approach 1:
Segmenting the magnetic core into portions with protrusions reduces magnetic attraction while maintaining the flux density required for precise position control, simplifying the control system.
Solution Approach 2:
The magnetic core structure is modified by adding protruding portions, changing the magnetic field distribution parameters to reduce attraction forces while preserving position control precision.
3Measurement precision
If additional position control mechanisms like voice coil motors are added, then position control precision is improved, but device complexity increases
Solution Approach 1:
The linear motor structure with segmented magnetic cores and protruding portions performs both high-speed driving and precise position control functions, eliminating the need for separate voice coil motors or additional control mechanisms.
4Ease of operation
If coreless motors are used, then magnetic attraction forces are reduced, but magnetic flux density and efficiency decrease
Solution Approach 1:
The magnetic core is segmented with protruding portions that reduce magnetic attraction forces similar to coreless motors, while still maintaining a magnetic core structure that provides high magnetic flux density and efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-speed and precise position control of the mask stage in three directions, synchronizing with substrate stage driving, without the need for additional position control mechanisms like voice coil motors, and achieving higher magnetic flux density than coreless motors.
Implementation Method 1
a coil wound around the magnetic core, currents of the same phase flowing through the coil
Implementation Method 2
a pair of linear motors that apply a thrust in the first direction and a thrust in the second direction to the holding unit
Implementation Method 3
a magnet module that includes a plurality of permanent magnets arranged in the first direction while changing poles
Data Source
AI summary
An object holding device includes a holding unit that holds an object and is driven in a first direction and a second direction orthogonal to the first direction in a horizontal plane, and a pair of linear motors that apply thrusts in the first and second directions to the holding unit, each of the linear motors including a first unit including armature modules each including a magnetic core having two or more protruding portions, which protrude in the second direction, and a coil wound around the magnetic core, currents of the same phase flowing through the coil, and a second unit including a magnet module that includes permanent magnets arranged in the first direction while changing poles and is arranged between two adjacent protruding portions, wherein a part of each of the permanent magnets is accommodated in a space sandwiched between the two adjacent protruding portions.