Heating-Sensing Circuit Bypass for Stable Capacitance Detection
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Solution Overview
Problem
Existing designs integrating heating and sensing functions in vehicles face challenges due to voltage fluctuations caused by transient conducted interference, leading to inaccurate capacitance detection and potential mistriggering, which compromises driving safety.
Innovation Solution
A circuit configuration that bypasses capacitance on the high-side driver by grounding the output terminal during sensing functions, utilizing MOSFETs for overcurrent and reverse-connection protection, and isolating electrical paths to stabilize capacitance detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If heating and sensing functions are integrated with time-shared control, then space requirements are reduced and costs are lowered, but voltage fluctuations during switching cause detection accuracy to deteriorate
Solution Approach 1:
The patent segments the control circuit into separate high-side and low-side drivers, each independently controlling different portions of the heating element. This segmentation allows for independent optimization of switching control, reducing voltage fluctuations during transitions and improving capacitance detection accuracy while maintaining the integrated structure.
Solution Approach 2:
The patent introduces an intermediary capacitor connected between the high-side driver output and ground. This capacitor acts as a buffer that smooths voltage transitions during switching between heating and sensing modes, reducing fluctuations in the sensing channel and improving detection accuracy without requiring separate physical layouts.
2Power
If heating function is activated or transient interference occurs, then power supply voltage fluctuates, but this causes Rawdata fluctuations that mimic human touch signals
Solution Approach 1:
The intermediary capacitor buffers voltage fluctuations from the high-side driver, preventing them from propagating to the sensing channel. This eliminates false touch signals caused by power supply variations while maintaining full heating power capability.
Solution Approach 2:
The patent extracts the voltage fluctuation problem from the main sensing path by providing a separate discharge path through the intermediary capacitor to ground. This isolates the sensing channel from power supply disturbances, ensuring reliable detection even during heating transitions or transient interference events.
3Loss of substance
If metal wire is used for both sensing and heating, then material costs are reduced, but switching between functions causes capacitance changes that reduce detection accuracy
Solution Approach 1:
The patent segments the control of the metal wire into high-side and low-side drivers, allowing precise control of switching transitions. This enables the single metal wire to serve both heating and sensing functions while minimizing spurious capacitance changes during mode transitions, maintaining detection accuracy.
Solution Approach 2:
The intermediary capacitor compensates for capacitance changes introduced by the metal wire during switching. By providing a stable reference and filtering high-frequency transitions, it enables accurate capacitance detection even when using a single metal wire for both heating and sensing functions.
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
Improves detection accuracy, reliability, and safety by minimizing the impact of heating function transitions on capacitance changes, ensuring stable and precise sensing operations.
Implementation Method 1
a switch unit... When the heating and sensing unit performs the sensing function, the signal processing unit controls the switch unit to be turned on, so as to ground the output terminal of the high-side driver
Implementation Method 2
a capacitance on a high-side driver side... fluctuations in the Rawdata representing changes in capacitance... accurately identifying changes in capacitance caused by human touch
Data Source
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AI summary
The present disclosure relates to a circuit, a detection system, and a device. The circuit is configured to couple with a heating and sensing unit to control the heating and sensing unit to perform a sensing function at a first time and a heating function at a second time. The circuit includes: a high-side driver, a signal processing unit, and a switch unit. A first terminal of the switch unit is grounded, a second terminal of the switch unit is connected to an output terminal of the high-side driver, and a third terminal of the switch unit is connected to the signal processing unit. When the heating and sensing unit performs the sensing function, the signal processing unit controls the switch unit to be turned on, so as to ground the output terminal of the high-side driver. The circuit bypasses a capacitance on the high-side driver side, thereby reducing the impact of battery voltage fluctuations and power line conducted noise immunity in experimental scenarios on the capacitance changes in the sensing detection channel, and improving detection accuracy as well as the stability, reliability, and safety of related products.