Actuator Energy Absorbing Element for Lithographic Apparatus Crash Protection
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Solution Overview
Problem
Lithographic apparatuses face the risk of mechanical failure, where the mover can crash into the stator, potentially causing damage due to the lack of effective crash protection mechanisms.
Innovation Solution
Incorporating an energy-absorbing element outside the gap between the stator and mover, which can absorb energy during a failure mode, reducing the risk of deformation and damage by transforming impact energy into elastic potential energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the gap between stator and mover is reduced to improve force efficiency, then the actuator becomes more compact and efficient, but the risk of crash damage increases
Solution Approach 1:
The patent applies beforehand cushioning by positioning an energy absorbing element (such as a spring or damper) between the stator and mover before any crash can occur. This element is pre-configured to absorb impact energy during normal operation and becomes active only during failure modes, cushioning the blow before it reaches critical components. The element is strategically placed to be compressed during normal operation but provides protective cushioning during crashes, thus resolving the contradiction between maintaining a small gap for force efficiency and protecting against crash damage.
2Reliability
If the energy absorbing element is placed inside the gap, then it can directly protect the stator, but it reduces the available gap length and forces efficiency
Solution Approach 1:
The patent resolves this contradiction by changing the spatial dimension of the energy absorbing element's placement. Instead of positioning the element along the primary motion axis (within the gap), it is placed in a secondary dimension or at the periphery of the gap. This allows the element to provide protection without significantly reducing the effective gap length available for force generation. The element may be positioned radially, axially offset, or at an angle, enabling it to absorb crash energy while maintaining the operational gap dimensions needed for force efficiency.
3Reliability
If a larger energy absorbing element is used to improve crash protection, then more energy can be absorbed, but the device complexity and space requirements increase
Solution Approach 1:
The patent employs flexible shells and thin films by utilizing compliant energy absorbing elements such as spring fingers, flexures, or thin-walled structures. These elements provide high energy absorption capacity relative to their size and mass. The flexible nature of these components allows them to deform significantly during impact, absorbing large amounts of energy while occupying minimal space. This approach enables effective crash protection without substantially increasing device complexity or space requirements, as the energy absorption is achieved through material compliance rather than bulk volume.
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 energy-absorbing element effectively mitigates the impact force, reducing the risk of damage to the stator and maintaining the efficiency of the actuator by minimizing deformation and extending the gap length, thus enhancing force efficiency.
Implementation Method 1
absorbing energy with the energy absorbing element by moving the stator relative to the first body
Data Source
AI summary
A lithographic apparatus comprises a system. The system comprises a first part, a second part and an energy absorbing element. The second part is configured to move relatively to the first part. The system has a gap located between the first part and the second part during an operation mode of the system. The energy absorbing element is for absorbing energy between the first part and the second part when the first part and the second part crash onto each other in a failure mode of the system. The energy absorbing element is outside the gap.