Ambient Light Sensor Window Coatings for Angle Sensitivity
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Solution Overview
Problem
Existing ambient light sensor window coatings in electronic devices introduce non-ideal characteristics, such as varying readings with the angle of incidence of incoming light, due to the use of dark ink which affects the accuracy and reliability of ambient light measurements.
Innovation Solution
A black physical vapor deposition thin-film inorganic layer with a high index of refraction, such as aluminum titanium nitride, is used in conjunction with an antireflection and color adjustment layer formed from a stack of dielectric layers to provide a coating that minimizes angle-of-incidence sensitivity and matches the appearance of the opaque masking layer, ensuring consistent light transmission and appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If dark ink coating is applied to the ambient light sensor window to improve appearance, then the visual blending with surrounding masking layer is improved, but the angle-of-incidence sensitivity increases and measurement precision deteriorates
Solution Approach 1:
The patent changes the optical parameters of the coating by using a dielectric material with specific refractive index (1.3-1.6) and controlling the thickness (50-200 nm) to achieve both aesthetic appearance and measurement precision. The coating is designed to have specific optical properties that reduce angle-of-incidence sensitivity while maintaining visual blending.
Solution Approach 2:
The patent uses a composite coating structure combining dielectric material with specific optical properties. The coating layer is formed over the ambient light sensor window and comprises a dielectric material with controlled thickness and refractive index, creating a composite structure that balances appearance and performance requirements.
2Shape
If dark ink coating is applied to mask the ambient light sensor window, then the visual blending with black ink masking layer is improved, but the light transmission consistency across different angles deteriorates
Solution Approach 1:
The patent optimizes the coating thickness parameter (50-200 nm) and refractive index (1.3-1.6) to achieve consistent light transmission across different angles. This specific parameter range ensures the coating appears dark enough to blend with the black ink masking layer while maintaining stable optical performance regardless of incident light angle.
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 reduces the sensitivity of ambient light sensors to variations in light angle of incidence, improving the accuracy and reliability of light measurements while maintaining a visually blended appearance with the surrounding masking layer.
Implementation Method 1
The black coating may include a black physical vapor deposition thin-film inorganic layer with a high index of refraction
Implementation Method 2
An antireflection and color adjustment layer may be interposed between the black thin-film inorganic layer and the display cover layer. The antireflection and color adjustment layer may be formed from a stack of dielectric layers such as a stack of metal oxide layers with alternating higher and lower indices of refraction
Data Source
AI summary
An electronic device may have a display with a cover layer. An ambient light sensor may be aligned with an ambient light sensor window formed from an opening in a masking layer on the cover layer in an inactive portion of the display. To help mask the ambient light sensor window from view, the ambient light sensor window may be provided with a black coating that matches the appearance of surrounding masking layer material while allowing light to reach the ambient light sensor. The black coating may be formed from a black physical vapor deposition thin-film inorganic layer with a high index of refraction. An antireflection layer formed from a stack of dielectric layers may be interposed between the black thin-film inorganic layer and the display cover layer.