Spectacle Lens Blue Light Blocking with Localized Reflectance Control
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Solution Overview
Problem
Spectacle lenses with multilayer films for selective blue light reflection on both surfaces can cause eye strain and discomfort due to the occurrence of double images, known as ghosts, which deteriorate the wearing experience.
Innovation Solution
A spectacle lens design featuring a lens substrate with a blue light absorbing compound and a multilayer film with a metal layer of 1.0 nm to 10.0 nm thickness, achieving a blue light cut ratio of 35.0% or more, reduces blue light entry while minimizing ghost formation by controlling reflectance on both surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a multilayer film with strong selective reflection of blue light is provided on both surfaces of the lens substrate, then the blue light blocking capability is improved, but the wearing comfort deteriorates due to ghost formation
Solution Approach 1:
The patent applies different reflectance characteristics to different surfaces of the lens. The object-side surface has higher blue light reflectance (15-25%) to block incoming blue light, while the eyeball-side surface has lower blue light reflectance (<2%) to prevent ghost formation. This local differentiation of optical properties resolves the contradiction between blue light blocking and wearing comfort.
2Object-affected harmful factors
If a metal layer with greater thickness is used in the multilayer film, then the blue light absorption is improved, but the luminous transmittance is significantly reduced
Solution Approach 1:
The patent optimizes the metal layer thickness to a specific range (1.0-10.0 nm) to achieve the desired balance. This precise parameter control allows sufficient blue light absorption while maintaining adequate luminous transmittance, resolving the contradiction between harmful factor reduction and illumination preservation.
3Object-affected harmful factors
If the blue light reflectance on the eyeball-side surface is increased to enhance blue light blocking, then the blue light cut ratio is improved, but the ghost intensity increases and wearing comfort deteriorates
Solution Approach 1:
The patent differentiates the optical properties between the two surfaces: the object-side surface reflects more blue light (15-25%) to achieve high blue light cut ratio, while the eyeball-side surface reflects minimal blue light (<2%) to prevent ghost formation. This local quality differentiation allows achieving high blue light blocking without increasing ghost intensity.
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 eye strain by blocking significant blue light and minimizing the visibility of double images, enhancing wearing comfort while maintaining adequate luminous transmittance.
Implementation Method 1
the lens substrate includes a blue light absorbing compound
Implementation Method 2
since a metal has the property of absorbing light in the visible range, the metal can also absorb blue light
Implementation Method 3
a multilayer film featuring selective strong reflection of light with a wavelength of 400 nm to 450 nm
Data Source
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AI summary
Provided is a spectacle lens including: a lens substrate including a blue light absorbing compound, and a multilayer film including a metal layer having a film thickness of 1.0 nm to 10.0 nm, wherein a blue light cut ratio is 35.0% or more, an average reflectance in a wavelength range of 400 nm to 500 nm on an object-side surface obtained by measurement from the object side is in a range of 15.00% to 25.00%, and an average reflectance in a wavelength range of 400 nm to 500 nm on an eyeball-side surface obtained by measurement from the object side is less than 2.00%.