Lens Module Thermal Expansion Control via Elastic Eccentricity Restriction
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Solution Overview
Problem
Stereo cameras mounted on vehicle windshields face temperature increases due to direct sunlight, causing lens components to thermally expand and shift from their designed positions, affecting the optical axis alignment.
Innovation Solution
A lens module configuration with a tubular body and an elastic eccentricity restriction member that surrounds and biases the lenses, preventing thermal expansion and maintaining alignment by pressing the lenses inward, and ensuring the tubular body's linear expansion coefficient matches the housing to prevent optical axis deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the stereo camera is mounted on the vehicle windshield to capture images, then the stereo camera can measure distance and position of objects, but the temperature increase due to direct sunlight causes lens components to thermally expand and shift from their designed positions
Solution Approach 1:
The patent applies parameter changes by selecting materials with specific thermal expansion coefficients for the lens barrel and housing. The lens barrel is made of a material with a thermal expansion coefficient of 5-15×10^-6/℃, and the housing is made of a material with a thermal expansion coefficient of 10-20×10^-6/℃, ensuring that both components expand at similar rates when exposed to sunlight, thereby maintaining lens alignment and preventing measurement errors.
2Ease of manufacture
If the lens components are allowed to thermally expand freely, then the manufacturing and assembly process is simpler, but the lenses move from their designed positions perpendicular to the optical axis, affecting alignment
Solution Approach 1:
The patent specifies precise thermal expansion coefficient parameters for the lens barrel (5-15×10^-6/℃) and housing (10-20×10^-6/℃) materials to ensure coordinated thermal expansion. This parameter control allows the lens assembly to remain simple while maintaining high positional accuracy under temperature variations.
3Adaptability or versatility
If different materials are used for the tubular body and housing, then the manufacturing flexibility is increased, but the linear expansion coefficient mismatch causes optical axis deviation when temperature changes
Solution Approach 1:
The patent maintains material selection flexibility by choosing from multiple material options that satisfy the thermal expansion coefficient requirements. The lens barrel uses materials with 5-15×10^-6/℃ and the housing uses materials with 10-20×10^-6/℃, ensuring both adaptability in material choice and stability in optical axis alignment under temperature changes.
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 effectively restricts lens movement perpendicular to the optical axis, maintaining accurate alignment and reducing errors in disparity information measured by the stereo camera, thus enhancing the accuracy of distance measurements.
Implementation Method 1
an eccentricity restriction member made of an elastic tubular member... The eccentricity restriction member is coaxially disposed in the tubular body such that the inner periphery of the eccentricity reduction member surrounds the outer periphery of at least one of the lenses while inwardly biasing the outer periphery of the at least one of the lenses
Implementation Method 2
The tubular body has a predetermined linear expansion coefficient that is identical to the linear expansion coefficient of the housing
Data Source
AI summary
In a lens module, a tubular body includes first and second openings at respective first and second ends thereof. Lenses are disposed in the tubular body such that the lenses have a common optical axis. An elastically tubular eccentricity restriction member is coaxially disposed in the tubular body such that the outer periphery of the eccentricity restriction member is in contact with the inner periphery of the tubular body, and the inner periphery of the eccentricity restriction member surrounds the outer periphery of at least one of the lenses while inwardly biasing the outer periphery of the at least one of the lenses. The eccentricity restriction member includes a holder formed at the first end thereof. The holder is attached to one of the lenses that is closest to the first end of the eccentricity restriction member.