Optical Member Boundary Anti-Reflection Structure

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Solution Overview

Problem

Optical members in instruments like cameras and binoculars experience significant light reflection at the boundary area between the optically effective and non-effective areas, leading to color unevenness and a degraded appearance, especially when the angle between these areas is between 45 degrees and 90 degrees.

Innovation Solution

A fine rugged structure is formed continuously on the optically effective area and the boundary area, with a light-shielding film applied only to the boundary area, reducing reflectance and preventing the occurrence of white ring-shaped color unevenness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a light-shielding film is applied to the optically non-effective area to reduce reflections, then the reflectance is reduced and harmful rays are prevented, but white ring-shaped color unevenness appears at the boundary area when the angle between effective and non-effective areas is large

Engineering Contradiction:
Improvereflection of harmful raysVSAvoidappearance uniformity
Core Design Contradiction:
Object-affected harmful factorsVSShape

Solution Approach 1:

The invention applies different treatments to different regions: the optically effective area receives an anti-reflection film, the boundary area receives a light-shielding film with specific optical characteristics, and the optically non-effective area receives a different treatment. This local differentiation resolves the contradiction by addressing the reflection problem at each zone according to its specific optical requirements, preventing the white ring phenomenon at the boundary while maintaining overall effectiveness.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the optical parameters of the boundary area by applying a light-shielding film with specific transmittance and reflectance characteristics that differ from both the anti-reflection film on the effective area and the treatment on the non-effective area. This parameter adjustment ensures that reflected light from the effective area is properly managed at the boundary, eliminating color unevenness while maintaining harmful ray suppression.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If an anti-reflection film is formed on the optically effective area to improve light transmittance, then harmful ray reflection is reduced, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvereflection at optically effective areaVSAvoidmanufacturing process complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention segments the optical member surface into three distinct zones (optically effective area, boundary area, and optically non-effective area) and applies different film treatments to each zone. This segmentation allows for targeted anti-reflection treatment on the effective area while using simpler light-shielding treatment on the boundary and non-effective areas, thereby reducing overall manufacturing complexity compared to uniform treatment of the entire surface.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If the angle between the optically effective area and the optically non-effective area is increased, then the optical design flexibility is improved, but reflected light is concentratedly irradiated onto the boundary area causing color unevenness

Engineering Contradiction:
Improveoptical design flexibilityVSAvoidappearance uniformity
Core Design Contradiction:
Adaptability or versatilityVSShape

Solution Approach 1:

The invention addresses the concentration of reflected light at the boundary area by applying a light-shielding film specifically to this region. This local treatment compensates for the increased light concentration caused by larger angles, allowing the optical design to maintain flexibility with various angles while preventing the white ring phenomenon that would otherwise occur.

Inventive Principle:
Principle #3Local quality

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 suppresses light reflections at the boundary area, enhancing the optical member's appearance by eliminating color unevenness and maintaining excellent optical characteristics even at large angles between the effective and non-effective areas.

Implementation Method 1

A fine rugged structure is formed continuously on the optically effective area and the boundary area

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

forming an ant-reflection film on the optically effective area of an optical member by laminating dielectric thin films

Methodology Applied
Scientific EffectAnti-reflection: Anti-Reflective Coating

Implementation Method 3

a light-shielding film is applied only to the boundary area, reducing reflectance and preventing the occurrence of white ring-shaped color unevenness

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP3223042B1Optical member and method of manufacturing the same
Publication Date: 2021.09.15 CANON KK
  • EP3223042B1 patent drawingFigure 1A~1B
  • EP3223042B1 patent drawingFigure 2~3

AI summary

An optical member includes a light-transmitting substrate having a surface including an optically effective area and an optically non-effective area, the optically effective area and the optically non-effective area being located adjacent relative to each other, the optically effective area and the optically non-effective area forming an angle of not less than 45 degrees and not more than 90 degrees on the border thereof. The optical member has a textured structure having an in-plane dimension of not greater than the use wavelength, the structure being formed continuously in a boundary area extending along the border of the optically effective area and the optically non-effective area, and a light-shielding film formed in a region including at least the boundary area of the optically non-effective area on the surface of the substrate.