Cooktop Boil-Over Electrode Layout for Accurate Capacitance Detection
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Solution Overview
Problem
Existing cooking devices with capacitance-based boiling-over detection systems face variability in electrode resistance, leading to inconsistent detection of boiled-over liquid, resulting in some devices failing to control heating output appropriately.
Innovation Solution
A cooking device with a ceramic top plate, a conductor electrode featuring a belt-like boiling-over detection part, a contact part, and a connection part, where the contact and connection parts are positioned farther from the heating device than the detection part, and the connection part is narrower than the detection part, allowing for accurate capacitance detection and uniform electrode resistance across devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional electrode design is used for boiling-over detection, then the device structure is simple, but the detection accuracy varies significantly among produced devices due to electrode resistance differences
Solution Approach 1:
The electrode is divided into three distinct parts: a boiling-over detection part (18) positioned near the outer periphery above the heating device, a contact part (21) positioned farther from the heating device, and a connection part (20) running through the outer peripheral side. This segmentation allows the detection part to be optimized for sensitivity while the contact and connection parts are optimized for stable electrical connection, resolving the contradiction between detection accuracy and device consistency.
2Measurement precision
If the contact part is positioned close to the heating device, then the electrode resistance is lower, but the capacitance change detection accuracy decreases due to large capacitance changes from the contact part itself
Solution Approach 1:
The contact part (21) and connection part (20) are extracted and positioned farther from the heating device than the boiling-over detection part (18). This separation removes the interfering capacitance changes from the contact and connection parts out of the primary detection zone, allowing the capacitance detection device to accurately measure only the changes in the boiling-over detection part caused by boiled-over liquid, while the electrode resistance is maintained through the proper configuration.
3Reliability
If the connection part is made wider to reduce resistance, then the electrical connection is improved, but the detection accuracy of boiled-over liquid decreases
Solution Approach 1:
Different parts of the electrode are given different widths optimized for their specific functions: the boiling-over detection part (18) is made with appropriate width for sensitivity, while the connection part (20) is configured to run through the outer peripheral side with sufficient width for reliable electrical connection. This local optimization allows each part to perform its function effectively without compromising the overall system performance.
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
Enables high-accuracy detection of boiled-over liquid across multiple cooking devices, ensuring consistent control of heating output and reducing capacitance changes in the contact and connection parts, thereby improving detection reliability.
Implementation Method 1
a capacitance detection device for supplying an AC voltage to the boiling-over detection part via the contact part to detect an increase or decrease in capacitance of the boiling-over detection part
Data Source
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AI summary
The cooking device includes a top plate 2 on which a container 3 is to be placed, heating devices 7, 8 provided below the top plate 2, electrodes 15, 16 provided in a lower face of the top plate 2 and including a boiling-over detection parts 18, 23 placed near an outer periphery of a portion of the top plate 2 positioned above the heating devices 7, 8, contact parts 21, 26 for supplying an AC current to the boiling-over detection parts 18, 23, and contact parts 21, 26 for connecting the contact parts 21, 26 and one-side ends of the boiling-over detection parts 18, 23 to each other, respectively, an electrode-use capacitance detection device 13 for detecting changes in capacitance of the boiling-over detection parts 18, 23, and a control device 9 for controlling the heating devices 7, 8 based on changes in capacitance detected by the electrode-use capacitance detection device 13. The contact parts 21, 26 are provided at positions farther from the heating devices 7, 8 and on a more front side of the cooking device than the boiling-over detection parts 18, 23, and the connection parts 20, 25 run through on the outer peripheral side of the boiling-over detection parts 18, 23.