In-Vehicle Capacitive Input Sensing for Vibration Noise Rejection
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Solution Overview
Problem
Capacitive input apparatuses in vehicles face erroneous detection due to external noise, such as vibrations, which complicates the circuit configuration and requires distinguishing between actual operation and noise-induced changes in capacitance.
Innovation Solution
A capacitive input apparatus with multiple electrodes spaced apart, utilizing a signal processing unit to generate input signals based on capacitance changes and a determination unit that considers threshold values and integral values over a predetermined period to accurately detect the presence of an operation object, reducing noise-induced errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse generation circuits are provided in each detection unit to reduce erroneous detection, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the pulse generation function into a single shared circuit that serves all detection units, rather than having separate pulse generation circuits in each detection unit. This merging approach reduces the overall number of circuits while maintaining the ability to perform accurate capacitive detection across all units, thereby reducing device complexity without sacrificing measurement precision
2Measurement precision
If multiple electrodes are used to distinguish operation from noise, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the detection area into multiple segmented electrodes arranged in a specific pattern. By segmenting the detection area and analyzing capacitance changes across multiple segments, the system can distinguish between actual operation objects and noise sources through spatial pattern recognition, improving measurement precision while using a manageable electrode configuration
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 effectively reduces erroneous detections by considering changes in adjacent electrodes, allowing for a simpler circuit configuration and improved accuracy in detecting operation objects, even in noisy environments.
Implementation Method 1
A capacitive input apparatus is used in a wide variety of fields. In a capacitive input apparatus, an input operation is performed by detecting a change in capacitance that occurs when an operation object such as a finger of an operator, a touch pen, or the like is brought in the proximity of the input apparatus
Implementation Method 2
a determination unit configured to determine whether an operation object has come in a proximity of at least one of electrodes based on a plurality of input signals output from the signal processing unit, the determination unit being configured to make a determination such that in a case where one of the input signals is greater than or equal to a predetermined first threshold value and an integral value of another of the plurality of input signals in a predetermined integration period is greater than or equal to a predetermined second threshold value
Data Source
AI summary
An input apparatus includes a plurality of electrodes spaced apart from each other, a signal processing unit configured to output an input signal depending on a change in a capacitance of each electrode, and a determination unit configured to determine whether an operation object comes in a proximity of at least one of electrodes based on input signals output from the signal processing unit. The determination unit makes a determination such that in a case where one of the input signals is greater than or equal to a first threshold value and an integral value of another of the plurality of input signals in a predetermined integration period is greater than or equal to a second threshold value, it is determined that an operation object has come in a proximity of an electrode corresponding to the one of the input signals.