Cooking Top Plate Coating for IR Sensing and Visible 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 the Si film and silicon nitride film are optimized within specific bounds to achieve high infrared transmittance and low visible light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light shielding film is formed on the top plate to achieve low transmittance in visible wavelength range, then the aesthetic appearance and invisibility of internal structure is improved, but the transmittance in infrared wavelength range of 3500 nm to 4000 nm decreases
Solution Approach 1:
The top plate is segmented into multiple functional layers: a glass substrate layer and a light shielding film layer with specific thickness parameters. This segmentation allows each layer to perform its specific function - the glass substrate provides structural support and infrared transmittance, while the light shielding film provides visible light blocking, thereby resolving the contradiction between aesthetic appearance and infrared transmittance
Solution Approach 2:
The invention optimizes the thickness parameters of the light shielding film (50-200 nm) to achieve the desired balance. By precisely controlling the film thickness within this range, the top plate blocks visible light effectively while maintaining sufficient transmittance for infrared wavelengths of 3500 nm to 4000 nm, thus resolving the contradiction between visible light shielding and infrared transmittance
2Measurement precision
If the top plate material is optimized for high infrared transmittance in wavelength range of 3500 nm to 4000 nm, then temperature detection accuracy is improved, but visible light transmittance increases affecting aesthetic appearance
Solution Approach 1:
The light shielding film acts as an intermediary layer between the glass substrate and the external environment. It mediates the conflicting requirements by blocking visible light to maintain aesthetic appearance while allowing infrared radiation to pass through for temperature detection, thus resolving the contradiction between temperature detection accuracy and aesthetic appearance
Solution Approach 2:
The top plate employs a composite structure combining glass substrate material with a light shielding film material. This composite material approach allows the system to simultaneously achieve high infrared transmittance (from the glass substrate) and low visible light transmittance (from the light shielding film), thereby resolving the contradiction between temperature detection accuracy and aesthetic appearance
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 coating ensures high transmittance in the infrared range of 3500 nm to 4000 nm while maintaining low transmittance in the visible range, enabling effective temperature detection across various temperature ranges and maintaining an aesthetically pleasing appearance by concealing internal structures.
Implementation Method 1
a top plate for a cooking device which allows the transmission of infrared light within a wavelength range of 3500 nm to 4000 nm but limits the transmission of light within a visible wavelength range to low levels
Implementation Method 2
the intensity of a wavelength portion up to 2500 nm of infrared light emitted from an object to be heated does not change so much with changes in temperature
Implementation Method 3
there is a need for detection of the temperature of the object to be heated. Examples of a method for detecting the temperature of an object to be heated are proposed, for example, in Patent Literatures 1 to 4 listed below, which are methods for detecting the temperature of an object to be heated by detecting the intensity of infrared radiation emitted from the object to be heated
Data Source
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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.