Layered Cooking Top Plate for Infrared Sensing and Light Shielding
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Solution Overview
Problem
Top plates for cooking devices require high transmittance in the infrared wavelength range of 3500 nm to 4000 nm for effective temperature detection while maintaining low transmittance in the visible wavelength range for aesthetic and functional reasons, but existing solutions fail to achieve this balance.
Innovation Solution
A top plate with a glass substrate coated with a layered structure of Si film and silicon nitride film, where the thicknesses of these films are optimized within specific bounds to achieve high infrared transmittance and low visible light transmittance, using a combination of sputtering and other thin film formation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light shielding film is formed on the top plate to achieve low visible light transmittance, then aesthetic appearance is improved, but infrared transmittance in the 3500 nm to 4000 nm range deteriorates
Solution Approach 1:
The patent applies composite materials by forming a layered coating structure consisting of multiple films with different optical properties. Specifically, it uses a combination of a first coating layer (e.g., silicon nitride or silicon oxide) and a second coating layer (e.g., silicon or silicon nitride), where each layer has different thicknesses and optical characteristics. This composite structure allows the top plate to simultaneously achieve low visible light transmittance (for aesthetic appearance) and high infrared transmittance in the 3500 nm to 4000 nm range (for temperature detection), resolving the contradiction between appearance and functionality.
2Measurement precision
If the top plate is made transparent to infrared light for temperature detection, then temperature detection accuracy is improved, but visibility of internal structure worsens
Solution Approach 1:
The patent applies local quality by creating a coating structure with spatially varying optical properties across different wavelength ranges. The layered coating is designed so that it exhibits different transmittance characteristics for visible light versus infrared light in the 3500 nm to 4000 nm range. Specifically, the coating has high transmittance for the specific infrared wavelengths needed for temperature detection while maintaining low transmittance for visible light, thereby achieving both accurate temperature measurement and aesthetic appearance by selectively controlling optical properties at different spectral regions.
3Ease of manufacture
If a single-layer coating is used to block visible light, then manufacturing simplicity is maintained, but the ability to simultaneously control visible and infrared transmittance deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the coating into multiple distinct layers, each with specific thicknesses and material compositions. Instead of using a single-layer coating, the invention employs a multi-layer structure where the first coating layer and second coating layer can be independently optimized. This segmentation allows precise control over the optical properties - the thickness and material of each layer are specifically designed to achieve the desired transmittance characteristics for both visible light and infrared light, providing the versatility needed to simultaneously satisfy aesthetic and functional requirements.
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 optimized top plate design enables accurate temperature detection across a wide range, including low temperatures, while maintaining an aesthetically pleasing appearance by ensuring high infrared transmittance in the 3500 nm to 4000 nm range and low visible light transmittance.
Implementation Method 1
a top plate for a cooking device includes: a glass substrate; and a layered coating made of a Si film and a silicon nitride film which are formed on the glass substrate... high transmittance in an infrared wavelength range of 3500 nm to 4000 nm
Implementation Method 2
low transmittance in a visible wavelength range... ensuring high infrared transmittance in the 3500 nm to 4000 nm range and low visible light transmittance
Implementation Method 3
low transmittance in a visible wavelength range... low visible light transmittance
Data Source
AI summary
To provide a top plate for a cooking device which has low transmittance in a visible wavelength range and high transmittance in an infrared wavelength range of 3500 nm to 4000 nm. A top plate 1 for a cooking device includes: a glass substrate 10; and a layered coating 2 made of a Si film 11 and a silicon nitride film 12 which are formed on the glass substrate 10. Where t1 represents the thickness of the Si film 11 and t2 represents the thickness of the silicon nitride film 12, (t1, t2) in FIG. 1 showing the relation between the thickness t1 of the Si film and the thickness t2 of the silicon nitride film is within the bounds X defined by connecting Points A1 to A36 shown in TABLE 1 in this order with straight lines.