Vehicle Camera Lens Alignment for Stress-Induced Focus Shift
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Solution Overview
Problem
Automotive cameras experience degradation in optical performance over time due to lens shifting out of alignment caused by mechanical and thermal stress cycles, leading to reduced depth of focus and failure to meet minimum MTF performance thresholds.
Innovation Solution
A lens alignment method that adjusts the position of the lens relative to the imager based on predetermined focus windows, compensating for adhesive shrinkage and aging effects, to maximize the depth of focus across all regions of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the lens position is adjusted to optimize focus for specific regions of interest during manufacturing, then the optical performance for those regions is improved, but the lens becomes vulnerable to misalignment over time due to stress relaxation
Solution Approach 1:
The alignment process performs preliminary actions by adjusting the lens position to optimize focus for specific regions of interest during manufacturing. This preliminary alignment sets up the lens position to achieve optimal optical performance at the time of assembly, though the patent acknowledges this creates vulnerability to later misalignment from stress relaxation.
Solution Approach 2:
The patent applies parameter changes by adjusting the lens position parameter during alignment to optimize focus for different regions of interest. The alignment process varies the lens position parameter to achieve optimal MTF values for each region, and the system compensates for adhesive shrinkage and desired focusing distance as part of this parameter adjustment.
2Duration of action of moving object
If the depth of focus is maximized by adjusting lens position, then the optical performance is optimized for regions of interest, but the lens alignment becomes sensitive to stress-induced position changes over time
Solution Approach 1:
The patent uses parameter changes to adjust the lens position to maximize depth of focus. By optimizing the lens position parameter during alignment, the system achieves extended depth of focus that maintains optical performance across regions of interest. The alignment process compensates for adhesive shrinkage and desired focusing distance as part of this parameter optimization.
3Manufacturing precision
If the lens is fixed in position using adhesive after alignment, then the alignment is secured, but adhesive shrinkage and thermal curing cause additional position shifts
Solution Approach 1:
The alignment process performs preliminary actions by adjusting the lens position to compensate for expected adhesive shrinkage and desired focusing distance before the adhesive is applied. This preliminary compensation ensures that when the adhesive cures and the lens is fixed, the optimal alignment position is already achieved, accounting for the shrinkage effect in advance.
Solution Approach 2:
The patent applies parameter changes to compensate for adhesive shrinkage by adjusting the lens position parameter during alignment. The system accounts for the shrinkage effect of the adhesive material and adjusts the lens position accordingly, ensuring that the final fixed position after curing maintains the optimal alignment for the desired focusing distance.
4Duration of action of stationary object
If the camera operates for extended periods, then the camera fulfills its operational requirements, but mechanical and thermal stress cycles cause lens position to shift over time
Solution Approach 1:
The alignment process performs preliminary actions by adjusting the lens position to optimize focus for specific regions of interest during manufacturing. This preliminary alignment sets up the lens position to achieve optimal optical performance at the time of assembly, though the patent acknowledges this creates vulnerability to later misalignment from stress relaxation during operation.
5Manufacturing precision
If the MTF peaks are aligned for optimal optical performance, then the focus is optimized for regions of interest, but the corner defocus reduces depth of focus at peripheral regions
Solution Approach 1:
The patent applies local quality by treating different regions of interest differently during alignment. Each region has its own MTF curve and focus characteristics, with peripheral regions experiencing corner defocus. The alignment process optimizes focus for each region individually, recognizing that central and peripheral regions have different optical performance characteristics and depth of focus requirements.
Data Source
AI summary
The present disclosure relates to lens alignment methods, lens alignment software, lens alignment apparatuses, and vehicle cameras. In an aspect, a lens alignment method includes performing a scan at a plurality of regions of interest of the lens to determine optical characteristics for each region of interest as the position of the lens relative to the imager is adjusted. Focus windows for each region of interest are determined based on the optical characteristics and the position of the lens relative to the imager is adjusted based on predetermined positions of the focus windows relative to one another.