Capacitance Input Device Noise Filtering via Threshold Segmentation
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Solution Overview
Problem
Existing input devices fail to accurately determine the position of an object in midair sensing layers due to noise interference from surrounding electronic devices, particularly in capacitance-based detection systems.
Innovation Solution
The input device employs a detection unit that measures capacitance thresholds and time thresholds to differentiate between various operational states, such as non-detection, proximity, selection, confirmation, and contact, using a controller to determine the relative state based on these measurements, thereby reducing noise interference and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance-based detection is used to detect object position in midair sensing layers, then detection capability is provided, but noise from surrounding electronic devices reduces measurement accuracy
Solution Approach 1:
The detection process is segmented into multiple discrete capacitance threshold levels (first threshold, second threshold, third threshold) corresponding to different midair sensing layers. By dividing the detection range into distinct segments, the system can identify which specific layer the object occupies, reducing ambiguity caused by noise and improving positional accuracy.
Solution Approach 2:
The system performs preliminary detection by measuring capacitance against multiple predetermined thresholds before final position determination. This preliminary action of comparing capacitance values against multiple threshold levels allows the system to pre-filter noise and establish the object's approximate location range before confirming the final position, thereby improving measurement precision.
2Measurement precision
If multiple capacitance thresholds are used to determine object position in different sensing layers, then position determination accuracy is improved, but detection time increases
Solution Approach 1:
The detection system dynamically adjusts its threshold comparison process based on capacitance values. The controller sequentially compares capacitance against multiple thresholds but can terminate the comparison early once a clear layer identification is established, optimizing detection time while maintaining accuracy. This dynamic approach prevents unnecessary prolonged detection when the object's position is clearly identifiable.
Solution Approach 2:
The system changes detection parameters by using multiple capacitance threshold levels to represent different sensing layers. By establishing predetermined threshold values corresponding to specific layers, the system can quickly map capacitance readings to positional information, improving both accuracy and efficiency of layer identification without requiring exhaustive measurement.
3Reliability
If noise filtering is implemented to reduce false detections, then reliability is improved, but response speed decreases
Solution Approach 1:
The system employs periodic capacitance sampling and threshold comparison at defined detection cycles. By structuring the detection process as periodic action with predetermined thresholds, the system can efficiently filter noise through consistent comparison criteria while maintaining fast response times. The periodic nature allows for systematic noise rejection without requiring continuous complex processing.
Solution Approach 2:
The system uses simple, discrete capacitance threshold comparisons rather than complex continuous analysis. Each threshold comparison is a simple, fast operation that can be quickly executed and discarded, allowing rapid sequential testing against multiple thresholds. This approach prioritizes speed with simple operations over complex but slower noise filtering algorithms, maintaining both reliability and responsiveness.
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
This approach enables the input device to quickly and accurately determine the position of an object in midair sensing layers, enhancing operational reliability and reducing errors caused by noise, allowing for precise interaction with GUI buttons in a contactless manner.
Implementation Method 1
a detection unit configured to detect a capacitance corresponding to a distance between the operation surface and an object
Data Source
AI summary
An input device includes a top panel having an operation surface, a detection unit configured to detect a capacitance corresponding to a distance between the operation surface and an object, and a controller configured to determine, based on a detection result from the detection unit, a relative state between the operation surface and the object to be one out of a non-detection state and a plurality of states. The controller measures, for each of the plurality of states, a duration in which the capacitance is greater than or equal to a corresponding one of capacitance thresholds set for the plurality of states, and determines, using the durations and the time thresholds and capacitance thresholds set for the plurality of states, the relative state to be one out of the non-detection state and the plurality of states.