Touch Sensor Protection Circuit for Overvoltage Isolation

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Solution Overview

Problem

Conventional techniques for implementing touch sensors in operational environments, such as vehicles, fail to efficiently provide isolation and protection for the sensors and their associated components from higher voltage adjacent circuits, leading to potential damage from short circuits.

Innovation Solution

A voltage protection circuit is configured to selectively pass AC and DC components of signals while blocking extraneous signals, using diodes and capacitors to isolate and protect microcontrollers from overvoltages, employing an RLC filter to filter high-frequency components and a discharge protection circuit to shunt excess current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If touch sensors are implemented adjacent to higher voltage electrical components in operational environments, then the sensors can function in diverse operational contexts, but the sensors and associated microcontrollers become vulnerable to damage from overvoltages and short circuits

Engineering Contradiction:

Improveoperational environment compatibilityVSAvoidprotection from overvoltages

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A protection circuit is introduced as an intermediary between the touch sensor/microcontroller and the higher voltage adjacent circuits. This protection circuit includes voltage detection circuitry that monitors voltage levels and activates protection mechanisms when overvoltages are detected, thereby isolating the sensitive components from harmful electrical conditions while allowing normal operation in diverse environments

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protection circuit is configured to detect overvoltage conditions before they can damage the microcontroller or touch sensor. By monitoring voltage levels continuously and activating protection mechanisms in advance, the system cushions the sensitive components from potential electrical damage, allowing them to operate reliably adjacent to higher voltage components

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Ease of manufacture

If conventional implementation techniques are used for touch sensors in operational environments, then the implementation is simple, but isolation and protection from adjacent higher voltage circuits is insufficient

Engineering Contradiction:

Improveimplementation simplicityVSAvoidexposure to overvoltages

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The protection functionality is merged with the existing touch sensor circuitry by integrating the voltage detection and protection activation into the same circuit board or module. This combining approach provides comprehensive protection without requiring separate isolated systems, maintaining ease of manufacture and implementation while significantly reducing exposure to harmful overvoltages

Inventive Principle:

Principle #5Merging (Combining)

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

Effectively isolates and protects microcontrollers from overvoltages, allowing continued operation of touch sensors by blocking harmful DC components and shunting excess current, thus preventing damage from short circuits.

Implementation Method 1

Methodology Applied

Scientific EffectDiode rectification: Diode

Implementation Method 2

Methodology Applied

Scientific EffectCapacitor coupling: Capacitance

Implementation Method 3

employing an RLC filter to filter high-frequency components

Methodology Applied

Scientific EffectRLC filtering: Filter (electronic)

Implementation Method 4

a discharge protection circuit to shunt excess current

Methodology Applied

Scientific EffectCurrent shunting: Shunt

Data Source

PatentUS12425027B2Systems, methods, and devices for sensor protection circuit

Publication Date: 2025.09.23 INFINEON TECHNOLOGIES AMERICAS CORP

AI summary

Systems, methods, and devices provide protection for sensing circuits. Methods may include providing, using a microcontroller unit (MCU), a drive signal to a touch sensor via an asymmetric conductance element of a protection circuit, providing, using the MCU, a scanning signal to the touch sensor via an additional conductance element of the protection circuit, and receiving, at the MCU, a sense signal from the touch sensor via the additional conductance element of the protection circuit. Methods also include determining, using the MCU, if a touch event has occurred based on measurements obtained during scanning of the touch sensor.