Gradient Photochromic Optical Article for Uniform and Variable Transmittance
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Solution Overview
Problem
Existing photochromic optical articles either provide a uniform color and darkness when exposed to actinic radiation, which is undesirable behind a UV attenuating transparency, or they exhibit a gradient color and darkness, which is less advantageous when exposed directly to actinic radiation.
Innovation Solution
An optical article that exhibits a uniform first percent transmittance when directly exposed to actinic radiation, a gradient second percent transmittance when exposed through an actinic radiation blocking or attenuating transparency, and a uniform third percent transmittance when not exposed to actinic radiation, with the uniform first percent transmittance being less than the uniform third percent transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If photochromic articles provide a uniform color and uniform level of darkness when exposed to actinic radiation, then the appearance is consistent across the lens, but viewing below the windshield (dashboard, instrument cluster, etc.) becomes difficult
Solution Approach 1:
The patent applies local quality by creating different regions within the optical article with different photochromic properties. Specifically, it uses a gradient photochromic composition where the concentration or type of photochromic compounds varies across different zones of the lens, allowing the top portion to darken uniformly for UV protection while the bottom portion maintains better visibility for viewing dashboard and instrument controls when behind a windshield.
2Ease of operation
If photochromic articles provide a gradient color and gradient level of darkness, then viewing below the windshield is improved, but the uniform level of darkness desired when outside a vehicle exposed directly to actinic radiation is compromised
Solution Approach 1:
The gradient photochromic composition is designed with spatially varying properties where specific regions respond differently to actinic radiation. The gradient structure allows the lens to provide enhanced viewing capability below the windshield while maintaining acceptable uniform darkness when exposed directly to sunlight, as different portions of the gradient are activated by the spectral composition of UV radiation filtered through the windshield versus direct sunlight.
3Object-affected harmful factors
If photochromic compounds transition to a second colored state when exposed to actinic radiation, then the transmittance decreases providing darkness protection, but the uniform reduced transmittance is not achieved when behind a UV attenuating transparency
Solution Approach 1:
The gradient photochromic composition creates zones with different transmittance characteristics. When behind a UV attenuating transparency like a windshield, the gradient structure ensures that regions receiving filtered UV radiation achieve appropriate darkness levels for comfort while maintaining visibility, rather than uniform over-darkening that would occur with homogeneous photochromic materials.
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 optical article achieves a uniform level of darkness when exposed directly to actinic radiation and a gradient effect when behind a UV attenuating transparency, while also maintaining a reduced level of darkness when not exposed to actinic radiation.
Implementation Method 1
When exposed to actinic radiation, photochromic compounds typically change from a first state (such as a bleached or first colored state providing a first transmittance) to a second state (such as a second colored state providing a second transmittance that is less than the first transmittance). When free of exposure to actinic radiation, photochromic compounds in the second state (such as the second colored state) will typically convert back to the first state (such as the bleached state).
Data Source
AI summary
The present invention relates to optical articles that exhibit a uniform first transmittance when directly exposed to actinic radiation, such as sunlight; a gradient second percent transmittance when exposed to actinic radiation that has passed through an actinic radiation blocking or attenuating transparency (such as a vehicle windshield) interposed between the source of actinic radiation and the optical article; and a uniform third percent transmittance when free of exposure to actinic radiation. With the inventive optical articles, the uniform first percent transmittance is less than the uniform third percent transmittance. The present invention also relates to photochromic optical articles.