Optical Unit Thermal Expansion Stress Relief
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Solution Overview
Problem
Existing optical units face challenges in maintaining optical performance due to thermal expansion, which leads to changes in dimensions and external stress, requiring separate processes for reflow soldering and increasing the number of components, thereby affecting cost and complexity.
Innovation Solution
The optical unit incorporates a cylindrical holder with angled contacting sections and gap sections to absorb thermal expansion, reducing external stress without additional components, allowing for stable holding and maintaining optical performance during thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lens unit is exposed to high temperature during reflow soldering, then the socket can be attached to the circuit board, but the lens thermally expands and presses against other components causing external stress that deteriorates optical performance
Solution Approach 1:
The patent introduces a cushioning component (elastic ring or elastic spacer) between the lens and the holder/pressing component. This cushioning element absorbs the thermal expansion of the lens during reflow soldering by deforming elastically, preventing the lens from pressing directly against other components. The cushioning component is positioned in advance to accommodate dimensional changes without transmitting stress to the lens, thereby maintaining optical performance while allowing high-temperature processing.
2Reliability
If separate processes are used for reflow soldering and lens mounting, then optical performance is maintained, but the number of processes and components increases
Solution Approach 1:
The patent merges the reflow soldering process and lens mounting process into a single high-temperature reflow soldering step. The cushioning component is designed to remain effective during this combined process, allowing the lens unit to withstand reflow temperatures without requiring separate mounting steps. This integration reduces the total number of manufacturing processes while the cushioning component ensures optical performance is maintained despite the thermal stress, thereby simplifying production without sacrificing reliability.
3Reliability
If elastic spacers and elastic rings are added to absorb thermal expansion, then external stress on the lens is reduced, but the number of components increases
Solution Approach 1:
The patent designs the cushioning component to perform multiple functions: it absorbs thermal expansion, reduces external stress on the lens, and maintains the positional relationship between the lens and holder. The cushioning component is integrated into the existing holder structure, combining the functions of stress absorption and mechanical support into a single element. This multi-functionality approach reduces the need for additional separate components while maintaining optical performance during thermal expansion.
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 solution effectively reduces changes in optical performance caused by thermal expansion, decreases the number of components, and achieves cost and size reductions by stabilizing the optical component within the holder, ensuring consistent performance.
Implementation Method 1
an amount of change in dimensions caused by thermal expansion of each component differs because of differences in the linear expansion coefficient of each component
Implementation Method 2
a dimensional change of the optical component during thermal expansion is absorbed by deformation of the elastic spacer and the elastic ring
Implementation Method 3
an elastic spacer presses a lens placed within a case, and an elastic ring surrounds an outer circumference of the lens
Data Source
AI summary
An optical unit is provided which includes gaps dR1 and dR2 in a radial direction that prevent an optical component from being affected by external stress during thermal expansion is formed between an outer circumferential surface of the optical component and an inner circumferential surface of a holder and gaps d0A1 and d0A2 that prevent the optical component adjacent to a pressing component from being affected by external stress during thermal expansion and are formed between predetermined surfaces on the pressing component and the optical component adjacent to the pressing component opposing each other in an optical axis direction.