Spring Element Supporting Unit for Vibration Isolation in Position Measuring Scales
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Solution Overview
Problem
Existing position measuring apparatuses using plate-like scales with grating patterns face challenges in maintaining precision due to vibration-induced deformations, particularly in the plate thickness direction, which can lead to inaccurate alignment of circuit patterns during exposure processes.
Innovation Solution
A supporting unit with a spring element is introduced between the structure and the scale to reduce vibration transfer in the plate thickness direction, utilizing magnetic repulsion forces and non-contact driving apparatuses to minimize deformation and enhance precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the scale is rigidly mounted on the lens barrel surface plate, then the scale is stable and resistant to displacement, but vibration from the structure is transferred to the scale causing deformation in the plate thickness direction
Solution Approach 1:
A supporting apparatus with spring elements is introduced as an intermediary between the lens barrel surface plate and the scale. This mediator absorbs vibration in the plate thickness direction while maintaining positional stability, preventing direct transmission of structural vibration to the scale.
Solution Approach 2:
The supporting apparatus is designed with specific natural frequency characteristics (less than 10 Hz) to selectively filter vibration frequencies. By changing the dynamic parameters of the support system, vibration at critical frequencies is attenuated while maintaining static positional accuracy.
2Adaptability or versatility
If the scale has high flexibility to accommodate structural deformation, then the scale can adapt to temperature changes, but vibration-induced deformation increases due to reduced stiffness
Solution Approach 1:
The support system is segmented into multiple spring elements arranged around the scale perimeter. This segmentation allows independent vibration isolation at each support point while maintaining overall scale stability and adaptability to thermal deformation.
Solution Approach 2:
The supporting apparatus combines elastic spring elements with rigid mounting structures to create a composite support system that provides both flexibility for thermal adaptation and stiffness for vibration resistance.
3Object-affected harmful factors
If the natural frequency of the supporting apparatus is increased, then the scale is less susceptible to low-frequency vibration, but the scale becomes more sensitive to high-frequency vibration and the supporting apparatus becomes stiffer transferring more vibration
Solution Approach 1:
The supporting apparatus is designed to provide excessive vibration isolation in the plate thickness direction, with a natural frequency less than 10 Hz that heavily attenuates vibration in this critical direction, while maintaining sufficient stiffness in lateral directions for measurement accuracy.
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 solution effectively reduces deformation of the scale to less than 0.1 nm, achieving the required precision for modern exposure apparatuses by setting the natural frequency of the supporting apparatus to less than 10 Hz and optimizing servo control frequencies to prevent resonance and vibration amplification.
Implementation Method 1
a spring element that reduces vibration transferred from the structure to the scale in a plate thickness direction
Implementation Method 2
the supporting unit includes a spring element
Implementation Method 3
a spring element that reduces vibration transferred from the structure to the scale in a plate thickness direction
Data Source
AI summary
A position measuring apparatus configured to measure a position of an measured object using a plate-like scale including a grating pattern, includes a supporting unit configured to be arranged between a structure and the scale and to support the scale, in which the supporting unit includes a spring element that reduces vibration transferred from the structure to the scale in a plate thickness direction.