Lens Holder Fixing Structure for Thermal Optical Axis Stability
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Solution Overview
Problem
Existing camera apparatuses experience shifting of the optical axis due to thermal stress caused by differing coefficients of linear expansion between the camera module and screws, leading to reduced fixing force and altered imaging range.
Innovation Solution
The imaging apparatus employs a holder with a housing and fixing member that have differing coefficients of linear expansion, where the length of the housing fixed by the fixing member is shorter than the length of the holder, thereby suppressing thermal stress and maintaining fixing force, thus stabilizing the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the camera module and screws are made of materials with different coefficients of linear expansion, then the fixing force is maintained, but thermal stress causes optical axis shifting
Solution Approach 1:
The holder is divided into a housing portion and a base portion, with the housing portion having a different material composition than the base portion. This segmentation allows each part to have different thermal expansion characteristics, enabling the housing to expand more than the base portion during temperature changes, thereby maintaining fixing force while preventing optical axis shifting
Solution Approach 2:
Different portions of the holder are assigned different material properties - the housing portion uses a material with a higher coefficient of linear expansion than the base portion. This local differentiation of material quality allows the housing to compensate for thermal expansion differences, maintaining both fixing force and optical axis stability
2Stress or pressure
If the housing length fixed by the fixing member is made shorter, then thermal stress is suppressed, but the fixing range is reduced
Solution Approach 1:
The patent changes the material parameter (coefficient of linear expansion) of the housing portion to be higher than that of the base portion. This parameter change allows the housing to expand more during temperature increases, reducing thermal stress accumulation. The shorter fixed length combined with this material parameter change effectively suppresses thermal stress while maintaining adequate fixing range
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 suppresses optical axis shifting and maintains accurate imaging by minimizing thermal stress and fixing force changes due to temperature variations, ensuring consistent performance.
Implementation Method 1
a coefficient of linear expansion of the housing and a coefficient of linear expansion of the fixing member differ
Data Source
AI summary
In an imaging apparatus, a holder includes a housing portion housing a lens, and a base portion extending in a direction orthogonal to an optical axis. A housing houses the base portion and an image sensor. A fixing member fixes the base portion and the housing. The fixing member includes a head portion that sandwiches the housing together with the base portion. A coefficient of linear expansion of the housing and a coefficient of linear expansion of the fixing member differ. A length in a direction of the optical axis from a portion of the base portion in contact with the housing to an end portion on a side opposite the portion in contact with the housing is longer than a length in the direction of the optical axis from a portion of the housing in contact with the head portion to a portion in contact with the base portion.