Capacitive Touch Input Device Noise Error Correction
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Solution Overview
Problem
Capacitive sensors used in touch input devices are susceptible to external electromagnetic noise, leading to errors in detecting object coordinates due to small changes in capacitance, which can be misinterpreted as noise-induced anomalies.
Innovation Solution
An input device with a sensor unit that performs periodic detection operations, generates coordinate data, and includes an error determination unit that calculates evaluation values based on velocity changes to identify and correct errors in coordinate data, using multiple acceleration vectors to assess the accuracy of detected coordinates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive sensor is used to detect object approach, then the detection sensitivity is improved, but the susceptibility to electromagnetic noise increases
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors coordinate data and uses acceleration information to detect anomalies. When noise is detected through abnormal acceleration patterns, the system feeds back correction decisions to replace erroneous coordinate data, thereby improving reliability while maintaining detection sensitivity
Solution Approach 2:
The patent introduces acceleration data as an intermediary element to mediate between raw coordinate detection and final output. By calculating acceleration from coordinate changes and using it as a validation criterion, the system can identify noise-induced anomalies without reducing the sensitivity of the original capacitive sensor
2Measurement precision
If periodic detection operation is performed at multiple positions, then the coordinate detection accuracy is improved, but the processing complexity increases
Solution Approach 1:
The patent performs preliminary calculations of acceleration vectors before making error determination decisions. By pre-calculating first, second, and third acceleration vectors from coordinate data, the system prepares validation criteria in advance, which simplifies the subsequent error detection and correction process despite the multiple detection positions
Solution Approach 2:
The patent calculates multiple acceleration vectors (first, second, and third) to provide redundant validation. This excessive calculation approach ensures robust noise filtering by comparing multiple acceleration metrics, with the benefit that only when these calculations reveal anomalies does the complexity impact performance
3Measurement precision
If error correction is performed based on velocity change evaluation, then the coordinate accuracy is improved, but the response time increases
Solution Approach 1:
The patent implements periodic error determination and correction at each detection cycle. By systematically evaluating acceleration vectors and coordinate consistency at regular intervals, the system maintains real-time responsiveness while ensuring accurate error detection and correction without excessive processing delays
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 errors in coordinate detection results caused by noise, ensuring accurate tracking of object positions by deferring corrections based on reliable error determination and maintaining accuracy even with large initial acceleration vectors.
Implementation Method 1
a sensor that detects a change in capacitance can detect the approach of an object (for example, a finger or a pen)
Data Source
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AI summary
An input device capable of reducing an error generated in a result of detection of coordinates of an object due to an influence of noise or the like is provided. Evaluation values (E1 to E3) regarding the change in velocity of an object at coordinates of a detection surface indicated by individual coordinate data 32 are calculated on the basis of a series of coordinate data 32 of the same object, and it is determined whether or not there is an error in each coordinate data 32 on the basis of the evaluation values (E1 to E3). Therefore, in a case in which an extreme change in velocity of the object apparently occurs due to the influence of noise or the like, it is possible to accurately determine the error of the coordinate data 32 on the basis of the evaluation values (E1 to E3). Further, since the coordinate data 32 in which it is determined that there is an error in time-series of coordinate data 32 of the same object is corrected with data indicating the same coordinates P as that of coordinate data 32 immediately before such coordinate data 32, the error of the detection result of the coordinates generated by the influence of noise or the like can be effectively reduced.