Phosphate Glass Optical Filter with Inorganic Coatings for IR Shielding
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Solution Overview
Problem
Existing optical filters for cameras, particularly those mounted on electronic devices like smartphones, face challenges in achieving high light shielding performance in the infrared region while minimizing angular dependence of optical properties, which becomes more pronounced as filters become more power-saving.
Innovation Solution
The optical filter employs a phosphate glass substrate containing an absorbent, such as CuO, coated with a first inorganic film on the main surface, a second inorganic film on the opposite main surface, and a third inorganic film on the end surface, without using an infrared cut film. This configuration enhances infrared absorption and reduces angular dependence of optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical filter uses a CuO-containing fluorophosphate glass substrate with a dye-containing layer and dielectric multilayer film to achieve high transmittance in visible light region, then the light shielding performance in infrared region is improved, but the angular dependence of optical properties becomes more prominent
Solution Approach 1:
The patent changes the glass substrate material from fluorophosphate glass to phosphate glass, which fundamentally alters the optical absorption characteristics. This parameter change enables the glass itself to provide strong infrared absorption without relying heavily on dye layers and dielectric multilayer films, thereby reducing angular dependence while maintaining high infrared light shielding performance
Solution Approach 2:
The patent creates a composite structure by combining phosphate glass substrate with specific inorganic film coatings. The phosphate glass provides inherent infrared absorption properties, while the inorganic films enhance both the infrared shielding and reduce angular dependence. This composite approach achieves both high reliability for infrared blocking and improved adaptability to varying incidence angles
2Use of energy by moving object
If an optical filter is designed to be more power saving for smartphone cameras, then energy consumption is reduced, but the angular dependence of optical properties becomes more prominent
Solution Approach 1:
The patent changes the glass composition from fluorophosphate to phosphate glass, which has different optical properties that reduce angular dependence. This material parameter change allows the filter to maintain effective performance across a wider range of incidence angles, compensating for the power-saving design that might otherwise exacerbate angular sensitivity
Solution Approach 2:
The patent applies different inorganic film coatings to different surfaces of the glass substrate (first inorganic film on first main surface, second inorganic film on second main surface, third inorganic film on end surface). This localized treatment optimizes each surface's optical properties to collectively reduce overall angular dependence while maintaining the power-saving design
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 provides significantly high light shielding performance in the infrared region and significantly reduces the angular dependence of optical properties, ensuring consistent performance even at varying incidence angles, thus addressing the limitations of existing filters.
Implementation Method 1
the glass substrate being a phosphate glass containing an absorbent
Implementation Method 2
the first main surface of the glass substrate is coated with a first inorganic film, and a second inorganic film is provided directly or indirectly on the second main surface of the glass substrate
Data Source
AI summary
An optical filter includes a glass substrate having a first main surface, a second main surface opposite the first main surface, and an end surface connecting the first and second main surfaces, the glass substrate being a phosphate glass containing an absorbent, and a first antireflection layer disposed directly or indirectly on the first main surface of the glass substrate, wherein the first main surface of the glass substrate is coated with a first inorganic film, and a second inorganic film is provided directly or indirectly on the second main surface of the glass substrate, with the end surface being coated with a third inorganic film, and wherein the first inorganic film is a film that is closest to the glass substrate among films constituting the first antireflection layer, or a film that is different from a film composed of a plurality of films constituting the first antireflection layer.