Resin Lens Thermal Deformation Control in Metal Barrel
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Solution Overview
Problem
The use of aluminum lens barrels with resin lenses in camera units leads to optical axis shift and deterioration in optical characteristics due to thermal expansion differences, causing deformation and misalignment of lenses.
Innovation Solution
A lens unit design featuring a metal lens barrel with metal intermediate rings and resin lenses, where the resin lenses have concave portions fitting with convex portions of the intermediate rings, maintaining a larger gap with the barrel than with the intermediate ring, ensuring minimal deformation and maintaining coaxiality of lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resin lenses are used in a metal lens barrel, then manufacturing cost is reduced and ease of manufacture is improved, but thermal expansion difference causes lens deformation and optical axis shift
Solution Approach 1:
A resin intermediate ring is introduced between the metal lens barrel and the resin lens. This intermediate ring has the same material composition as the resin lens, ensuring consistent thermal expansion characteristics. The intermediate ring serves as a mediator that transfers thermal expansion forces uniformly, preventing direct thermal stress from the metal barrel from deforming the resin lens and causing optical axis shift.
Solution Approach 2:
The linear expansion coefficient of the intermediate ring is specifically designed to match or closely approximate that of the resin lens. By adjusting the material selection and dimensional parameters of the intermediate ring, the thermal expansion mismatch between the metal barrel and resin lens is compensated, maintaining optical axis alignment across temperature variations.
2Stability of the object's composition
If the lens is tightly fixed in the lens barrel, then position stability is improved, but thermal expansion difference causes radial deformation of the lens
Solution Approach 1:
The resin intermediate ring acts as a buffer between the lens barrel and the lens. It provides a compliant interface that allows the lens to expand radially with temperature changes while maintaining its positional stability in the optical axis direction. The intermediate ring absorbs the thermal expansion stress without transmitting it to the lens, preventing radial deformation.
Solution Approach 2:
The intermediate ring provides different functional characteristics at different locations: it maintains tight radial contact with the lens barrel for position stability, while simultaneously providing a compliant interface with the lens to allow thermal expansion. This localized differentiation of mechanical properties resolves the contradiction between stability and deformation prevention.
3Reliability
If glass lenses are used, then optical characteristics are maintained, but manufacturing cost increases and device complexity increases
Solution Approach 1:
The patent changes the material parameter from glass to resin for the lenses and intermediate ring. By selecting resin materials with appropriate optical properties and matching thermal expansion coefficients, the system achieves cost reduction and simplified manufacturing while maintaining sufficient optical performance for the application.
Solution Approach 2:
The patent employs composite material strategies by using resin materials for both the lenses and the intermediate ring, creating a homogenous material system that simplifies manufacturing. This composite approach (resin lens + resin intermediate ring) replaces the heterogeneous glass-metal combination, reducing device complexity while maintaining optical characteristics through careful material selection.
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 suppresses optical axis shift and maintains desired coaxiality of lenses, preventing deterioration in optical characteristics by minimizing radial deformation of resin lenses and ensuring precise alignment.
Implementation Method 1
Since the lens 51 is made of resin, a difference in linear expansion coefficient between the lens 51 and the lens barrel 50 is large. At a high temperature, the flange portion 51b of the lens 51 expands radially outward
Data Source
AI summary
A lens unit can inhibit deterioration in optical characteristics caused due to deformation of resin lens. The lens unit includes: a metal lens barrel; a plurality of lenses arranged on the inner peripheral side of the lens barrel in the axial direction thereof; and an annular intermediate ring disposed between the lenses adjacent to each other in the axial direction. The intermediate ring is made of metal and has a convex portion formed toward the image side or the object side. The lens is made of resin, having a concave portion fitted with the convex portion. A gap formed between the outer peripheral surface of the lens and the inner peripheral surface of the lens barrel is larger than a gap formed between the outer peripheral surface of the intermediate ring and the inner peripheral surface of the lens barrel.