Two-Layer Air Suspension Cantilever for High-Stiffness Motion
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Solution Overview
Problem
Existing aerostatic linear motion reference devices in lithography machines face challenges in achieving high rotational stiffness per unit area, which is essential for high-speed, high-precision, and high-frequency motion, especially in the exposure system where traditional sliding/rolling rails fail to meet these requirements due to complexity and miniaturization needs.
Innovation Solution
A cantilever linear motion reference device employing a two-layer air suspension structure, comprising a two-layer air suspension sliding sleeve component with a U-shaped configuration, a vertical drive motor, vertical and driven rails, and a suspended counterweight, which enhances rotational stiffness and motion accuracy through force-sealed air suspension and precise feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional sliding/rolling rails are used in the aerostatic linear motion reference device, then the structure is simple and easy to manufacture, but the rotational stiffness per unit area is insufficient and cannot meet high acceleration motion requirements
Solution Approach 1:
The patent employs aerostatic bearing technology with air suspension rails and air cushion support to replace traditional mechanical sliding/rolling rails. The air suspension system generates high rotational stiffness through pneumatic pressure while maintaining frictionless operation, enabling high acceleration motion without complex mechanical contact structures.
Solution Approach 2:
The patent changes the fundamental support mechanism from mechanical contact to aerostatic suspension, transforming the physical state of support from solid-to-solid contact to gas-cushioned support. This parameter change enables high rotational stiffness per unit area while reducing structural complexity and eliminating friction.
2Ease of operation
If the diaphragm is disposed at the cantilever end to prevent blocking optical path, then the optical path is not blocked, but the rotational torque generated at high acceleration requires higher rotational stiffness
Solution Approach 1:
The aerostatic rail system provides high rotational stiffness through pneumatic pressure distribution along the rail length, enabling the cantilevered diaphragm to resist rotational torque during high acceleration motion without blocking the optical path.
3Volume of moving object
If the aerostatic linear motion mechanism is miniaturized for the exposure system, then the device volume is reduced, but the rotational stiffness per unit area becomes insufficient
Solution Approach 1:
The patent transforms the support mechanism from mechanical to aerostatic, enabling high rotational stiffness per unit area in a miniaturized configuration. The air suspension system's pneumatic pressure distribution provides superior stiffness-to-volume ratio compared to traditional mechanical rails.
4Strength
If single-layer air suspension is used, then the structure is simple, but the rotational stiffness and support capacity are insufficient for high-speed high-precision motion
Solution Approach 1:
The patent employs a two-layer nested air suspension structure where an inner air suspension rail is positioned within an outer air suspension rail. This nested configuration provides enhanced support capacity and rotational stiffness through distributed pneumatic pressure while maintaining a compact overall structure.
Solution Approach 2:
The two-layer air suspension system combines multiple pneumatic support elements into a composite suspension structure, where the interaction between inner and outer air cushions provides superior load support and rotational stiffness compared to single-layer systems.
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
The two-layer air suspension design improves rotational stiffness per unit area, reduces friction and heat loss, and enables high-speed, high-precision, and high-frequency motion with compact volume, suitable for the exposure system of lithography machines.
Implementation Method 1
two-layer air suspension structure
Data Source
AI summary
A cantilever linear motion reference device employing two-layer air suspension. By means of a two-layer force sealed air suspension structure, the invention realizes two-dimensional air suspension support and motion guiding and improves the rotational stiffness per unit for an air suspension working surface. By combining accurate driving and feedback control, the invention achieves high speed, high acceleration, high frequency motion, and enables construction of a small-volume, long cantilever, high torque load two-dimensional motion reference device.