Capacitive Input Device Noise Immunity via Preliminary Signal Extraction
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Solution Overview
Problem
Existing capacitive input devices face challenges with noise immunity and operability, as they require multiple data accumulations to reduce noise, leading to impaired followability and potential false detection due to incomplete noise removal.
Innovation Solution
An input device with a coordinate input unit, capacitance measuring unit, and control unit that performs noise removal and smoothing processes using difference values and Gaussian-weighted averages, allowing for accurate operation position calculation without extensive data accumulation, thereby enhancing noise immunity and operability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple data accumulations are performed to reduce noise influence, then noise immunity is improved, but processing speed is reduced and followability deteriorates
Solution Approach 1:
The patent applies preliminary action by performing a noise removal process before the weighted average calculation. The control unit identifies and removes noise components from capacitance values in advance, so that subsequent processing can proceed with already-cleaned data, eliminating the need for multiple accumulations and improving processing speed while maintaining noise immunity
Solution Approach 2:
The patent extracts noise components from the capacitance measurement data through a dedicated noise removal process. By separating and removing the noise portion from the total capacitance signal, the system can process cleaner data with fewer accumulations, thus improving both noise immunity and processing speed
2Reliability
If multiple data accumulations are performed to reduce noise influence, then noise immunity is improved, but operability deteriorates due to impaired followability
Solution Approach 1:
The control unit performs noise removal as a preliminary step before coordinate calculation and weighted average processing. This preliminary action ensures that the data used for operation detection is already cleaned of noise, allowing for faster response times that maintain good followability and operability without sacrificing noise immunity
3Productivity
If noise removal is incomplete, then processing speed is maintained, but false detection occurs and measurement precision deteriorates
Solution Approach 1:
The patent implements a specific noise removal process that extracts noise components from capacitance measurements. By identifying and removing noise portions before weighted average calculation, the system achieves both fast processing speed and high detection accuracy, preventing false detections while maintaining productivity
Solution Approach 2:
The control unit performs iterative noise removal and coordinate calculation, using the results to refine the detection process. This feedback mechanism ensures that noise is adequately removed without requiring excessive accumulations, balancing processing speed with 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 effectively reduces noise influence and improves detection precision, ensuring good followability and operability by calculating accurate operation positions quickly and accurately.
Implementation Method 1
a capacitive input device that determines an operation position by sensing a variation in capacitance
Data Source
AI summary
An input device includes a coordinate input unit including capacitance detectors, a capacitance measuring unit that measures the capacitances of the capacitance detectors and outputs them as measurement signals by performing A/D conversion, and a control unit that controls the capacitance measuring unit, obtains the signals while associating them with coordinate information of the capacitance detectors, calculates first data signals that are difference values between the measurement signals and a reference value, performs a calculation for the first data signals, outputs control signals based on the calculation result, performs a first calculation in which the first data signals obtained after performing a noise removal process are associated with the coordinate information as second data signals and a second calculation in which the second signals obtained after performing a smoothing process are associated with the coordinate information as third data signals, and calculates an operation position using the third data signals.