Vehicle Camera Lens Barrel Contact Layout for Thermal Strain Control
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Solution Overview
Problem
Camera modules in vehicles face issues with thermal strain and optical performance deterioration due to temperature changes, particularly in ADAS systems where camera lenses are exposed to varying ambient conditions, leading to misalignment and reduced image quality.
Innovation Solution
A camera module design incorporating a thermal compensation lens system with a flange portion of the second lens contacting the lens barrel, where the contact surface length is 20% to 50% of the flange portion's thickness, and the radii of curvature of the object-side and sensor-side surfaces differ by 1 mm or more, minimizing thermal strain and maintaining optical reliability across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the camera module uses conventional lens materials and structures, then the manufacturing is simple, but the optical properties change with ambient temperature causing thermal strain
Solution Approach 1:
The patent applies parameter changes by selecting lens materials with specific refractive indices and abbe numbers that compensate for thermal effects. The first lens has a refractive index of 1.70-2.00 and abbe number 25-45, while the second lens has a refractive index of 1.50-1.70 and abbe number 30-50. These parameter selections ensure that the combined optical system maintains stable focal length and image quality across temperature variations from -30°C to 85°C, resolving the contradiction between reliability and complexity.
Solution Approach 2:
The patent employs composite material strategy by combining two different lens materials with complementary optical and thermal properties. The first lens uses a high refractive index material (1.70-2.00) while the second lens uses a lower refractive index material (1.50-1.70). This composite approach allows the system to achieve thermal compensation through the differential expansion and refractive index changes of the two materials, improving optical performance stability without requiring complex active control mechanisms.
2Strength
If the lens flange contacts the lens barrel over a large area, then the mechanical support is strong, but the thermal strain is increased
Solution Approach 1:
The patent applies local quality principle by creating a non-uniform contact structure between the lens flange and lens barrel. The contact area is designed to be localized at specific regions rather than distributed uniformly across the entire flange surface. This localized contact provides sufficient mechanical support while minimizing the total contact area, thereby reducing heat transfer and thermal strain accumulation. The contact regions are positioned to maintain optical alignment while allowing thermal expansion of the lens elements.
3Ease of manufacture
If the radii of curvature of lens surfaces are made similar, then the manufacturing is easier, but the optical performance changes with temperature
Solution Approach 1:
The patent applies parameter changes by establishing specific relationships between the radii of curvature of different lens surfaces. The first lens has an object-side radius R1 and image-side radius R2, while the second lens has an object-side radius R3 and image-side radius R4. The patent specifies that |R1 - R2| ≥ 0.5mm and |R3 - R4| ≥ 0.5mm, creating asymmetric curvature profiles that compensate for thermal effects. This asymmetric design maintains manufacturing feasibility while achieving temperature-independent optical performance through the differential curvature changes of the two lenses.
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 reduces thermal strain and maintains optical performance by adjusting the contact position and area between the lens flange and barrel, suppressing changes in optical characteristics and ensuring reliable camera module operation across temperature extremes.
Implementation Method 1
a third surface and a fourth surface of the second lens have different radii of curvature on an optical axis, wherein a center of the first contact surface may be located closer to a side having a greater radius of curvature among the third surface and the fourth surface based on a center of the thickness of the flange portion
Data Source
AI summary
The camera module disclosed in the embodiment of the invention includes a lens barrel having a through hole therein; and first, second and third lenses coupled to the through hole of the lens barrel and aligned with an optical axis from an object side to a sensor side. The materials of the first and second lenses are different, a refractive index of the second lens is lower than a refractive index of the first lens, the second lens includes a flange portion extending from the optical axis toward an inner surface of the lens barrel, and a length of a first contact surface in which the flange portion of the second lens contacts the inner surface of the lens barrel is 20% to 50% of a thickness of the flange portion. An object-side third surface and a sensor-side fourth surface of the second lens have different radii of curvature on the optical axis, and a center of the first contact surface where the flange portion of the second lens contacts the inner surface of the lens barrel may be located closer to a side having a greater radius of curvature among the third surface and the fourth surface based on a center of the thickness of the flange portion.