Resin Lens Fitting Clearance for Stereo Camera Alignment
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Solution Overview
Problem
The existing lens units with resin lenses face misalignment issues due to temperature changes and manufacturing defects, such as D-shaped cuts, which affect the accuracy of image formation and distance measurement in stereo cameras used in vehicles.
Innovation Solution
A lens unit design featuring a resin lens with a flange and a fitting portion of smaller diameter, fitted into a lens barrel with clearance over the entire circumference, to reduce misalignment and accommodate temperature changes, using a pressing member to secure the lens perpendicular to the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin lens is used to reduce costs, then manufacturing cost is reduced, but misalignment between lens barrel and lens axes occurs due to D-shaped cuts and temperature changes
Solution Approach 1:
The lens mounting structure is divided into multiple functional zones: a fitting portion with clearance fit for radial positioning, an abutting surface for axial positioning, and a pressing member for securing. This segmentation allows each zone to address specific alignment requirements independently, maintaining precision despite the resin lens's D-shaped perimeter
Solution Approach 2:
The fitting portion acts as an intermediary between the lens barrel and the resin lens, providing a clearance fit that accommodates manufacturing variations and thermal expansion while maintaining proper alignment. This intermediate structure absorbs dimensional discrepancies without transmitting them to the optical axis
2Ease of manufacture
If the lens housing chamber is shaped to accommodate the gate, then the gate can be positioned, but the lens alignment precision deteriorates
Solution Approach 1:
The lens structure is segmented into a flange portion that accommodates the gate and a fitting portion that ensures alignment. By separating these functions into distinct structural zones, the gate can be positioned on the flange without interfering with the precision alignment provided by the fitting portion
Solution Approach 2:
Different regions of the lens mounting structure have different functional qualities: the flange area provides gate accommodation and structural support, while the fitting portion provides precise radial positioning through clearance fit. This local differentiation allows each region to optimize its specific function without compromising overall alignment
3Stability of the object's composition
If pressing force is applied to secure the resin lens, then the lens is fixed in position, but misalignment increases due to temperature changes
Solution Approach 1:
The fitting clearance between the fitting portion and lens housing chamber is specifically designed to accommodate thermal expansion and contraction of the resin lens. The clearance parameter is optimized to maintain proper alignment across the operating temperature range while still providing sufficient radial positioning
Solution Approach 2:
The pressing member is designed to apply controlled force that secures the lens against the abutting surface without excessive radial compression. This pre-applied force compensates for thermal variations by maintaining consistent contact pressure, preventing misalignment caused by temperature-induced expansion or contraction
Data Source
AI summary
A lens unit includes: a resin lens including a flange forming an outer peripheral portion of the resin lens and a fitting portion having a diameter smaller than a diameter of the outer peripheral portion of the flange; a lens barrel including a lens housing chamber and an abutting surface, the lens housing chamber housing the resin lens with the fitting portion facing the abutting surface; and a pressing member pressing the resin lens against the abutting surface along an optical axis of the resin lens. The fitting portion being fit into the lens housing chamber over an entire circumference of the fitting portion with clearance between the entire circumference and the lens housing chamber to position the resin lens in a direction perpendicular to the optical axis of the resin lens.