Interference Filter Fixation for Thermal Warping
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Solution Overview
Problem
Existing optical filter devices face issues with warping due to thermal expansion differences between substrates and adhesive contraction, leading to degradation of optical properties and potential mechanical failures.
Innovation Solution
An optical filter device configuration where the interference filter is fixed with a fixing member on one side of the filter region, with spacer portions outside the filter region, allowing for thermal expansion and contraction without warping and enhancing impact resistance by acting as stoppers during mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the interference filter is fixed to the entire surface of the base substrate, then the fixation strength is improved, but the reflection film warps due to thermal expansion difference
Solution Approach 1:
The fixing method is segmented from full-surface bonding to localized point fixing. The interference filter is fixed only at specific positions (corners or edges) using adhesive, while the rest of the surface remains unbonded. This segmentation allows the reflection film to maintain its flatness by reducing the area subject to thermal stress, while still providing sufficient fixation strength through the distributed point contacts.
Solution Approach 2:
The base substrate is designed with locally differentiated properties: a hard substrate material provides structural support and thermal stability, while strategically positioned adhesive applications provide localized bonding. This local quality approach allows the system to achieve both strong fixation and minimal warping by concentrating bonding only where necessary rather than across the entire surface.
2Ease of manufacture
If adhesive is used to fix the interference filter, then the ease of manufacture is improved, but the reflection film warps due to adhesive contraction
Solution Approach 1:
Instead of applying adhesive across the entire surface (excessive action), the invention uses partial action by applying adhesive only at specific positions such as corners or edges. This partial application is sufficient to achieve the required fixation strength while minimizing the total amount of adhesive used, thereby reducing the cumulative contraction effect that causes warping during adhesive hardening.
3Stability of the object's composition
If the interference filter is fully bonded to the base substrate, then the mechanical stability is improved, but the impact resistance deteriorates due to stress concentration
Solution Approach 1:
The bonding structure is segmented from continuous full-surface bonding to discrete point bonding. By fixing the interference filter only at specific positions (corners or edges) rather than across the entire surface, the system maintains mechanical stability through distributed point contacts while creating stress relief zones that prevent stress concentration during impact, thereby improving impact resistance.
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
This configuration stabilizes optical properties and ensures sufficient impact resistance by managing thermal stress and mechanical loads effectively.
Implementation Method 1
there was a concern that a reflection film is warped due to an effect from a difference in both coefficients of thermal expansion, based on temperature change
Implementation Method 2
ensures sufficient impact resistance by managing thermal stress and mechanical loads effectively
Data Source
AI summary
An interference filter is fixed with respect to a base substrate by a fixing member which is disposed on one portion which is on the outer side of a filter region. Accordingly, since the periphery end of the interference filter, other than a portion (end portion) in which the fixing member is disposed, becomes a floated state (free end), it is possible to suppress the warping of the interference filter even when there is the difference in coefficients of thermal expansion with the base substrate. Further, spacer portions which are lower than the height of the fixing member are formed outside the filter region and on the portion separated from the fixing member. At the time of the impact, since the spacer portions come in contact with the base substrate to function as stoppers, it is possible to suppress occurrence of peeling-off or cracks on the fixing member.