Multilayer Eyeglass Lens Coating for Ghost Light Suppression
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Solution Overview
Problem
Conventional spectacle lenses with multilayer films suffer from high ghost light intensity due to uncontrolled reflection characteristics, which reduces visibility by allowing intense ghost light to enter the wearer's eye, and existing evaluations focus primarily on stimulus value Y under fluorescent lighting, neglecting color perception improvements.
Innovation Solution
A spectacle lens design with controlled reflection characteristics on both surfaces, where one surface has a maximum reflectance exceeding 2.00% and the other surface has reflectance of 2.00% or less, with specific reflectance ratios and refractive index layers to suppress ghost light intensity to 1.50 E-02 or less in XYZ tristimulus values, using multilayer films with high and low refractive index layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional multilayer films are designed to reflect light with high reflectance in certain wavelength bands, then color preference and aesthetic appearance are improved, but ghost light intensity increases and visibility deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the reflectance values of both surfaces within specific ranges (1.5-5.0% for first surface, 0.5-2.0% for second surface) and adjusting the product of reflectances at specific wavelength bands to satisfy Expression (1). This quantitative parameter control transforms the conventional approach of high reflectance design into a optimized balance that reduces ghost light while maintaining color preference.
Solution Approach 2:
The patent employs composite materials through multilayer film structures with alternating high-refractive-index and low-refractive-index layers. By combining materials with different refractive indices (such as TiO2, SiO2, ZrO2, Nb2O5) in specific layer configurations, the patent achieves controlled reflection characteristics that satisfy both color preference and ghost light reduction requirements simultaneously.
2Ease of manufacture
If multilayer films are designed to match color suited to wearer's preferences, then aesthetic appearance is improved, but visibility deteriorates due to increased ghost light
Solution Approach 1:
The patent changes the reflectance parameters from conventional high reflectance values to optimized ranges (1.5-5.0% and 0.5-2.0% for the two surfaces respectively). By controlling the product of reflectances Rb1×Rb2, Rg1×Rg2, and Rr1×Rr2 to satisfy Expression (1), the patent achieves a balance where aesthetic appearance is maintained through controlled color reflection while visibility is improved by reducing ghost light intensity.
3Illumination intensity
If ghost light intensity is reduced by controlling reflectance characteristics, then visibility is improved, but reflection characteristics and color preferences may be compromised
Solution Approach 1:
The patent applies parameter changes by defining specific reflectance ranges for both surfaces (1.5-5.0% for first surface, 0.5-2.0% for second surface) and establishing the mathematical relationship in Expression (1) that must be satisfied. These parameter specifications ensure that ghost light is reduced for improved visibility while the controlled reflectance values maintain desirable color reflection characteristics and aesthetic appearance.
Solution Approach 2:
The patent uses composite multilayer film structures with alternating high and low refractive index layers to achieve the desired reflection characteristics. The specific layer configurations and material combinations enable simultaneous optimization of visibility (through ghost light reduction) and aesthetic appearance (through controlled color reflection).
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 design effectively reduces ghost light intensity, enhancing visibility and color perception by minimizing ghost light entry into the eye, while maintaining desired reflection characteristics and color preferences.
Implementation Method 1
the ghost light intensity is reduced by configuring the lens such that one surface exhibits a maximum value of the reflection near a certain wavelength, while the other surface exhibits a minimum reflectance near the same wavelength
Implementation Method 2
the multilayer film on the surface 2 side includes one or more layers having a refractive index of 1.20 or more and 1.38 or less
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
Provided is a spectacle lens including a lens substrate, and multilayer films respectively located on an object-side surface and an object-side surface of the lens substrate. A maximum value in a wavelength band of 380 nm to 780 nm on the object-side surface or an eyeball-side surface of the spectacle lens exceeds 2.00%, a surface where the maximum value exceeds 2.00% is defined as a surface 1, and the other surface is defined as a surface 2, Rb1 is an average reflectance in a wavelength band of 420 nm to 440 nm on the surface 1, Rb2 is an average reflectance in the wavelength band of 420 nm to 440 nm on the surface 2, Rg1 is an average reflectance in a wavelength band of 530 nm to 540 nm on the surface 1, Rg2 is an average reflectance in the wavelength band of 530 nm to 540 nm on the surface 2, Rr1 is an average reflectance in a wavelength bands of 440 nm to 460 nm and 560 nm to 580 nm on the surface 1, Rr2 is an average reflectance in the wavelength bands of 440 to 460 nm and 560 to 580 nm on the surface 2, Rb2, Rg2, and Rr2 are each 2.00% or less, and the spectacle lens satisfies all of Expressions 1 to 3 below. Rb1*Rb2<2.0 Rg1*Rg2<2.0 Rr1*Rr2<2.0