Capacitive Touch Input Wake-Up for False Activation Filtering
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Solution Overview
Problem
Conventional touch input devices for vehicles often remain in a power-saving mode due to limited battery life, leading to failure in detecting user touch inputs and misinterpreting environmental changes as touch inputs, resulting in incorrect operation.
Innovation Solution
A method and device that differentiate between user touch inputs and environmental changes by scanning function and comparison touch buttons, using a tact switch to generate a wake-up signal based on capacitance changes, and a microcontroller unit to determine the intention behind the capacitance changes, thereby accurately distinguishing between user inputs and environmental influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the touch input device remains in power-saving mode to extend battery lifetime, then energy consumption is reduced and battery lifetime is extended, but the device fails to detect user touch inputs and misinterprets environmental changes as touch inputs
Solution Approach 1:
The patent segments the detection function by introducing a separate wake-up detection mechanism (tact switch) that operates independently from the main capacitive touch detection system. This allows the main system to remain in low-power mode while the wake-up detector monitors for genuine user input through mechanical pressure detection, thus maintaining detection accuracy without increasing overall energy consumption.
Solution Approach 2:
The patent introduces a tact switch as an intermediary component between the user and the capacitive touch sensor. This intermediary mechanically validates user intent by requiring actual pressing action, thereby filtering out false environmental capacitance changes. The tact switch acts as a mediator that confirms genuine user input before triggering wake-up or function execution, resolving the contradiction between power-saving mode and reliable detection.
2Reliability
If the device wakes up to detect capacitance changes, then user touch inputs can be detected, but environmental changes such as humidity and temperature are misrecognized as touch inputs causing false activations
Solution Approach 1:
The patent applies preliminary anti-action by requiring dual validation before responding to capacitance changes. The system first checks for mechanical pressure through the tact switch, and only then processes capacitive touch data. This preliminary verification prevents environmental factors like humidity and temperature from causing false activations, as these factors cannot simultaneously trigger the mechanical tact switch.
Solution Approach 2:
The system performs preliminary action by pre-validating user input intent through the tact switch before activating the full touch detection system. The mechanical pressure detection on the tact switch serves as a preliminary confirmation that a genuine user interaction is occurring, filtering out environmental capacitance variations before they can cause false wake-up or function activation.
3Device complexity
If conventional capacitive touch buttons are used without comparison buttons, then device complexity is reduced, but the ability to distinguish between user input and environmental changes is lost
Solution Approach 1:
The patent merges the wake-up detection function and the touch input detection function into a unified system. The tact switch serves dual purposes: it detects wake-up intent through mechanical pressure and simultaneously validates genuine user interaction. This merging reduces the need for separate comparison touch buttons while maintaining the ability to distinguish between environmental changes and user input, thus reducing device complexity without sacrificing measurement precision.
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 solution enables accurate detection of user touch inputs while maintaining power-saving modes, reducing false activations and improving user experience by distinguishing between intentional and environmental capacitance changes.
Implementation Method 1
a tact switch configured to detect a change in capacitance by bottom compression of at least one air gap disposed between the at least one touch electrode and the at least one function touch button and to generate a wake-up signal
Implementation Method 2
a microcontroller unit configured to compare a capacitance generated by the at least one function touch button with a capacitance generated by the at least one comparison touch button and to determine whether a touch input corresponds to an intention of a user or to an environmental change
Data Source
AI summary
A method for detecting a touch input can include: scanning at least one function touch button of the touch input device and at least one comparison touch button of the touch input device; determining whether an expected touch input corresponds to an intention of a user or to a first environmental change causing the change in capacitance generated by the at least one function touch button; comparing the change in capacitance generated by the at least one function touch button with the change in capacitance generated by the at least one comparison touch button; and determining whether the expected touch input is a determined touch input corresponding to the intention of the user or a touch input corresponding to a second environmental change based on the comparison.