Imaging Lens Ghosting Suppression via Curvature and Distance Parameters
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Solution Overview
Problem
In-vehicle cameras face challenges in maintaining image quality due to infrared rays entering the imaging element, leading to ghosting issues and degradation, especially when using infrared ray filters or coatings that compromise anti-reflection performance.
Innovation Solution
An imaging lens with a specific configuration, including a front group with negative power and a rear group with positive power, featuring a convex shape for certain lens surfaces and an infrared ray cut coat, satisfies specific curvature and distance conditions to suppress ghosting without the need for separate infrared filters, maintaining optical performance across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an infrared ray filter or coating is applied to prevent infrared rays from entering the imaging element, then infrared interference is reduced, but anti-reflection performance deteriorates and ghosting issues occur
Solution Approach 1:
The patent applies an infrared ray cut coat with specific parameters (curvature radius Rr of the second lens surface, curvature radius Re of the third lens surface, and distance Da between them) to achieve both infrared blocking and anti-reflection functions. By precisely controlling these parameters to satisfy the condition (Rr + |Re|)/Da, the system eliminates the need for separate infrared filters while maintaining optical performance.
2Object-affected harmful factors
If a separate infrared filter is added to block infrared rays, then infrared interference is prevented, but device complexity increases
Solution Approach 1:
The patent merges the infrared blocking function and anti-reflection function into a single integrated solution by applying the infrared ray cut coat to the third lens surface with specific curvature and positioning parameters. This consolidation eliminates the need for separate infrared filters and maintains optical performance without increasing device complexity.
Solution Approach 2:
The infrared ray cut coat on the third lens surface serves multiple functions simultaneously: it blocks infrared rays, provides anti-reflection properties, and maintains optical performance across temperature variations. This multi-functionality eliminates the need for additional separate components.
3Device complexity
If the lens configuration is simplified without separate infrared filters, then device complexity is reduced, but ghosting from reflected light increases
Solution Approach 1:
By precisely controlling the curvature radii (Rr, Re) and distance (Da) parameters of the lens surfaces, the patent achieves optimal optical performance that suppresses ghosting. The specific condition (Rr + |Re|)/Da ensures that the simplified lens configuration without separate filters still maintains high image quality and minimizes reflected light interference.
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 imaging lens effectively reduces ghosting caused by reflected light, maintaining image quality and optical performance while preventing infrared interference, even in extreme temperature conditions, with a simple configuration that does not require additional elements like infrared filters.
Implementation Method 1
a third lens surface closest to an image side has a convex shape toward the image side, and the third lens surface has an infrared ray cut coat
Implementation Method 2
a first lens surface closest to the object side has a convex shape toward the object side. In the rear group, a second lens surface closest to the object side has a convex shape toward the object side
Data Source
AI summary
An imaging lens includes a front group having negative power, an aperture stop, and a rear group having positive power, in order from an object side. In the front group, a first lens surface has a convex shape toward the object side. In the rear group, a second lens surface has a convex shape toward the object side, a third lens surface has a convex shape toward the image side, and the third lens surface has an infrared ray cut coat. A curvature radius of the second lens surface is represented by Rr, a curvature radius of the third lens surface is represented by Re, a distance from the second lens surface to the third lens surface on an optical axis is represented by Da, and the following condition is satisfied: 1.6<(Rr+|Re|)/Da<2.3.