Passive Gravity Compensator With Adjustable Magnetic Force
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Solution Overview
Problem
Existing passive gravity compensators for semiconductor processing equipment lack a mechanism for adjusting the gravity compensation force effectively, which limits their adaptability and precision in supporting wafer tables moving in the Z-direction.
Innovation Solution
A passive gravity compensator with a force adjustment device that includes a guiding system and an adjustment mechanism using screws to adjust the relative position of permanent magnets between a stationary and a movable unit, allowing for perpendicular movement and precise control of the gravity compensation force along the X- or Y-direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive gravity compensator is used instead of an active device, then the device becomes less expensive, more reliable, and more durable, but the ability to adjust and control the gravity compensation force is reduced
Solution Approach 1:
The patent introduces a force adjustment device that enables the passive gravity compensator to dynamically adjust its compensation force by modifying the relative position between permanent magnets. This dynamic adjustment capability resolves the contradiction by providing adaptability while maintaining the passive, reliable structure without requiring active actuators.
Solution Approach 2:
The invention changes the physical parameter of magnet spacing through the force adjustment device, allowing the gravity compensation force to be tuned. By adjusting the distance between magnets, the system can adapt to different load conditions while remaining a passive device, thus improving adaptability without sacrificing reliability.
2Measurement precision
If the position of permanent magnets is adjusted to modify gravity compensation force, then the adaptability and precision are improved, but the device complexity increases
Solution Approach 1:
The force adjustment device is segmented into distinct functional components: a guiding system for constrained movement and an adjustment mechanism (screws) for precise positioning. This segmentation allows precise control of magnet positions while keeping each component simple and manageable, resolving the contradiction between precision and complexity.
Solution Approach 2:
The patent replaces complex active control systems with a simple mechanical adjustment mechanism using screws and rails. This mechanical substitution achieves precise force adjustment through straightforward mechanical means, avoiding the complexity of electronic controls while maintaining high precision in force compensation.
3Manufacturing precision
If screws are used for adjustment, then the adjustment precision is improved with ±1 mm control, but the risk of screw loosening over time increases
Solution Approach 1:
The guiding system with rails and sliders is implemented as a preliminary action to pre-constrain the adjustment components. This preliminary mechanical guidance prevents screw loosening by eliminating lateral movements and rotational tendencies before they can occur, ensuring long-term stability while maintaining adjustment precision.
Solution Approach 2:
The rail-slider mechanism acts as an intermediary between the adjustment screws and the permanent magnets. This intermediary component translates screw rotation into precise linear motion while constraining the system against loosening, thereby mediating between the precision requirement and the stability requirement.
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 adjustable gravity compensation force within a range of 5 to 35 N, providing precise control and maintaining a constant force over a stroke length, with ±10% variation in force controlled by ±1 mm of X-variation, enhancing the reliability and durability of the compensator.
Implementation Method 1
The gravity compensator further includes a force adjustment device adapted to be mounted on the stationary unit of the semiconductor equipment and adapted to adjust the relative position between the permanent magnet of the first assembly and the first and second permanent magnets of the second assembly
Data Source
AI summary
A passive gravity compensator for a semiconductor equipment, which includes a stationary unit and a movable unit adapted to move relative the stationary unit in a Z-direction, includes a first assembly and a second assembly. The first assembly includes a magnet holder and a permanent magnet fixed to the magnet holder. The second assembly includes a magnetic yoke having first and second opposite parts and first and second permanent magnets mounted against the first and second opposite parts of the magnetic yoke to face each other and to form a gap therebetween. One of the first and second assemblies of the gravity compensator is adapted to be mounted on the stationary unit of the semiconductor equipment, and the other of the first and second assemblies of the gravity compensator is adapted to be mounted to the movable unit of the semiconductor equipment, such that the permanent magnet of the first assembly is movable inside the gap located between the first and second permanent magnets of the second assembly. The gravity compensator further includes a force adjustment device adapted to be mounted on the stationary unit of the semiconductor equipment. The force adjustment device is adapted to adjust the relative position between the permanent magnet of the first assembly and the first and second permanent magnets of the second assembly along an X or Y direction to adjust the gravity compensation force.