Multilayer Light-Blocking Film with Color-Differentiated Layers

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Solution Overview

Problem

The challenge lies in creating a multilayer light-blocking film with high optical density whose front and back surfaces can be easily discriminated, especially in small sizes where differentiation is difficult, and in preventing manufacturing failures due to poor incorporation during module assembly.

Innovation Solution

The solution involves setting a predetermined color difference ΔE*ab between the first and second light-blocking layers, and using inclined end surfaces as marks to facilitate discrimination of the front and back surfaces, thereby improving handling and reducing manufacturing errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the size of the light-blocking film is reduced to several centimeters square or less for miniaturization, then the camera module achieves miniaturization, but it becomes extremely difficult to discriminate the front and back of the light-blocking film

Engineering Contradiction:
Improvecamera module sizeVSAvoiddiscrimination of front and back surfaces
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The patent applies color changes by forming a first light-blocking layer and a second light-blocking layer with different colors (different ΔE*ab values). This allows operators to easily distinguish the front and back surfaces of the miniaturized light-blocking film through color differentiation, solving the discrimination difficulty while maintaining small size.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent applies asymmetry by creating asymmetric structures on the end surfaces - specifically forming inclined end surfaces or protrusions that are asymmetric in shape. This asymmetric feature provides a clear visual and tactile marker for distinguishing front from back, enabling easy discrimination despite the film's small size.

Inventive Principle:
Principle #4Asymmetry

2Object-affected harmful factors

If the optical density of the light-blocking layers is increased to improve light-blocking performance, then halation and lens flare are reduced, but the difficulty of discriminating front and back surfaces increases

Engineering Contradiction:
Improvehalation and lens flareVSAvoiddiscrimination of front and back surfaces
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent applies color changes by ensuring the first and second light-blocking layers have different colors (ΔE*ab ≥ 0.2) while both maintaining high optical density. This allows the film to effectively block light (reducing halation and lens flare) while the color difference provides visual cues for discrimination.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent applies local quality by differentiating the properties of the first and second light-blocking layers - specifically their colors - while both layers maintain high optical density for light-blocking function. The localized color variation enables discrimination without compromising the overall light-blocking performance.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If thorough control of front and back surfaces is implemented to prevent manufacturing failures, then incorporation accuracy improves, but the burden of parts control increases and productivity decreases

Engineering Contradiction:
Improveincorporation accuracyVSAvoidmanufacturing efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies self-service by designing the light-blocking film with built-in visual markers (color differences and asymmetric end surface features) that enable self-identification of front and back surfaces. This self-marking system eliminates the need for complex external inspection systems or manual verification procedures, maintaining high incorporation accuracy while preserving productivity.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3637156B1Multilayer light-blocking film, and light blocking ring for optical equipment, lens unit, and camera module using same
Publication Date: 2025.05.07 KIMOTO CO LTD
  • EP3637156B1 patent drawingFigure 1~2
  • EP3637156B1 patent drawingFigure 3~4
  • EP3637156B1 patent drawingFigure 5

AI summary

There are provided a multilayer light-blocking film and the like whose front and back surfaces are easy to discriminate while they have light-blocking layers having high optical density whose front and back are usually difficult to discriminate. A multilayer light-blocking film 100 has a multilayer structure comprising at least a substrate film 11, a light-blocking layer 21 provided on one major surface 11a side of this substrate film 11, and a light-blocking layer 31 provided on the other major surface 11b side, the light-blocking layer 21 and the light-blocking layer 31 have an optical density of 2.5 or more in total, and for the light-blocking layer 21 and the light-blocking layer 31, the color difference ΔE*ab is different by 0.2 or more in the CIE 1976 L*a*b* color system. The substrate film 11 and the light-blocking layer 21 and/or the light-blocking layer 31 preferably have inclined end surfaces 12, 22, and/or 32 so that a film width increases from the light-blocking layer 21 toward the light-blocking layer 31.