Capacitive Sensor Open Conductor Track for Induction Hob
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Solution Overview
Problem
Induction hob devices face inefficiencies in detecting cooking utensils and reducing power losses, as existing systems require time to set up induction coils and can induce eddy currents, leading to unnecessary heating and power wastage.
Innovation Solution
The implementation of a capacitive sensor unit with an open conductor track that detects objects by generating a sensor signal based on capacitance changes, allowing for quick recognition of cooking utensils and reducing power losses by minimizing eddy currents through a structured conductor track arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mobile induction coils are moved laterally under the hob plate to detect cooking utensils, then the detection capability is improved, but the detection time increases and delays the readiness of the induction hob device
Solution Approach 1:
The patent replaces the mechanical scanning system with mobile induction coils with a capacitive sensor field distributed across the hob plate. The capacitive sensor unit continuously monitors the entire surface without mechanical movement, substituting mechanical scanning with electromagnetic field-based detection. This eliminates the time delay associated with moving coils while maintaining detection precision.
Solution Approach 2:
The capacitive sensor unit is continuously active and ready to detect cooking utensils at any position on the hob plate, rather than scanning sequentially. This preliminary readiness state allows immediate detection when a utensil is placed, eliminating the waiting time inherent in sequential scanning mechanisms.
2Speed
If induction coils operate continuously to maintain readiness, then the detection response time is improved, but power losses increase due to eddy currents and unnecessary heating
Solution Approach 1:
Instead of continuous operation, the induction coil is activated periodically only when the capacitive sensor detects a cooking utensil. The sensor continuously monitors for presence, and the heating element engages only when needed, converting continuous operation into event-driven periodic action. This reduces energy losses from eddy currents and unnecessary heating while maintaining rapid response capability.
Solution Approach 2:
The capacitive sensor unit autonomously detects the presence of cooking utensils and triggers the induction coil operation only when required. This self-service mechanism eliminates the need for continuous monitoring and control, allowing the system to remain in a low-power state until detection occurs, thereby reducing overall energy consumption.
3Reliability
If a closed conductor track is used for the sensor surface, then the electrical connectivity is improved, but eddy currents are induced causing unnecessary heating and power wastage
Solution Approach 1:
The conductor track is segmented into multiple sections with intentional interruptions, preventing the formation of continuous closed loops. This segmentation maintains electrical connectivity for sensor operation while breaking the paths that would allow eddy currents to form. The conductor track is divided into discrete segments that can still function electrically without creating harmful current loops.
Solution Approach 2:
The harmful closed-loop structure is extracted and removed from the conductor track design. By taking out the continuous circular path and replacing it with an open, segmented configuration, the design eliminates the source of eddy currents while preserving the essential electrical connectivity needed for capacitive sensing functionality.
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 rapid detection of cooking utensils and efficient heating by reducing power losses and avoiding unnecessary induction coil operations, ensuring targeted heating and improved measurement accuracy.
Implementation Method 1
a capacitive sensor unit (10) with at least one sensor surface (12) having at least one open conductor track (14) is provided under the hob plate (24). The sensor unit (10) has at least one sensor surface (12) with at least one open conductor track (14).
Implementation Method 2
Some of these have mobile induction coils that can be moved laterally under the hob plate to a set-up position for the cooking utensil. The set-up position is determined by scanning the hob plate with the mobile induction coils, which takes up at least some of the periods in which the induction hob device is not yet ready to heat the cookware.
Data Source
Figure 1~2
Figure 3a~3b
Figure 4
AI summary
The invention relates to a cooktop device, in particular an induction cooktop device, with at least one capacitive sensor unit (10a; 10b). In order to provide a generic device with advantageous properties with regard to the capacitive detection of an object, it is proposed that the sensor unit (10a; 10b) has at least one sensor surface (12a; 12b) with at least one open conductor track (14a; 14b).