Lens Unit Coating Structure for High-Temperature Resin Lens Durability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Resin lenses in in-vehicle cameras face durability issues due to cracking from thermal expansion differences with reflection preventing films, especially at high temperatures, and are prone to damage from external contacts.
Innovation Solution
A lens unit configuration with a glass lens exposed to the outside and resin lenses inside, where the resin lenses are coated with a high-temperature resistant reflection preventing film, and the glass lens has an ultra-hard coating, while the resin lenses are bonded without the film between them to prevent adhesive interference with optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resin lenses are coated with conventional reflection preventing films, then optical characteristics are improved, but the films crack at high temperatures due to thermal expansion differences
Solution Approach 1:
The patent changes the material parameters of the reflection preventing film by using low thermal expansion glass materials (such as glass ceramic or borosilicate glass) instead of conventional coatings. This parameter change in thermal expansion coefficient matches the resin lens material, preventing cracking at high temperatures while maintaining optical characteristics.
Solution Approach 2:
The patent uses composite material structure where a reflection preventing film made of glass ceramic or borosilicate glass is applied on resin lenses. This composite approach combines the low thermal expansion properties of glass materials with the optical characteristics needed, resolving the contradiction between film integrity and optical performance at high temperatures.
2Ease of manufacture
If resin lenses are used to reduce manufacturing cost, then cost is reduced, but the lenses are more prone to damage from external contacts
Solution Approach 1:
The patent changes the surface property parameters of resin lenses by applying glass ceramic or borosilicate glass films, which have higher hardness and strength than the resin material itself. This parameter change in surface properties provides damage resistance while keeping the bulk material as cost-effective resin.
Solution Approach 2:
The patent creates a composite structure with resin lens body and glass film surface layer. The resin provides cost-effectiveness and appropriate thermal expansion, while the glass surface layer provides hardness and damage resistance, resolving the contradiction between manufacturing cost and strength.
3Strength
If glass lenses are used for the forefront lens to improve durability, then durability is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by providing glass ceramic or borosilicate glass coating only on specific surfaces of resin lenses (the reflection preventing film surfaces), rather than making the entire lens from expensive glass. This localized application provides durability where needed while maintaining cost-effectiveness for the overall lens structure.
Solution Approach 2:
The patent uses composite material approach where the majority of the lens is made from cost-effective resin material, while only the critical surface layers are made from durable glass ceramic or borosilicate glass. This composite structure optimizes the balance between durability and manufacturing cost.
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 enhances durability and optical performance by preventing film cracking and damage at high temperatures, reducing manufacturing costs, and maintaining performance under harsh conditions.
Implementation Method 1
a glass lens or a resin lens is coated with a reflection preventing film. Such reflection preventing film increases a light transmittance, improves a lens contrast
Implementation Method 2
The reflection preventing film is formed on the glass lens or the resin lens by vacuum deposition
Implementation Method 3
the cracking is caused due to a difference in thermal expansion coefficient between the resin lens and the reflection preventing film
Data Source
AI summary
An improved lens unit can be used in an in-vehicle camera or the like, in a condition where a forefront lens is exposed to the outside for a long time. Here, the resin lens within the lens unit has an improved durability at a high temperature. The lens unit has a plurality of lenses arranged side by side with the optical axes thereof aligned with each other. The lenses include glass lens and resin lens. The lens closest to the object is a glass lens which is closest to the object side and is coated with an ultra-hard film. Resin lenses each have a high temperature resistant reflection preventing film. The lens is a combined lens in which a lens and a lens are bonded together, and is then covered with a high temperature resistant reflection preventing film after bonding.