Touch-Type Input Device Parasitic Capacitance Reference Value Update
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Solution Overview
Problem
Mutual capacitive touch-type input devices fail to accurately detect touching due to changes in parasitic capacitance caused by wear and ambient environmental factors, leading to erroneous reference values and incorrect detection.
Innovation Solution
A touch-type input device with a sensor array of drive and sensor electrodes arranged in a grid pattern, where a controller applies drive signals to detect capacitance changes and re-obtains parasitic capacitance values when an erroneous reference value is determined, ensuring accurate detection by updating reference values based on capacitance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the touch-type input device obtains a reference value for detecting capacitance change when activated, then the device can detect touching based on capacitance variations, but the parasitic capacitance may have changed due to wear or ambient environment, leading to erroneous reference values and incorrect touch detection
Solution Approach 1:
The patent applies preliminary action by obtaining the parasitic capacitance value before actual touch detection begins. The controller measures and stores the parasitic capacitance of each capacitor when the touch panel is not being touched, establishing a baseline reference value that accounts for current environmental conditions and wear state. This preliminary measurement ensures that subsequent touch detections are based on accurate reference values, resolving the contradiction between measurement precision and reliability.
2Reliability
If the parasitic capacitance changes due to wear or ambient environmental factors like temperature, then the reference value becomes erroneous, but continuously updating the reference value may introduce new errors from external noise or objects contacting the device
Solution Approach 1:
The patent implements feedback by continuously monitoring the parasitic capacitance values and comparing them against predetermined thresholds or variation ranges. When the parasitic capacitance changes exceed acceptable limits, the system automatically triggers a re-obtaining of the reference value. This feedback mechanism ensures that reference values are updated only when necessary, maintaining reliability while avoiding unnecessary updates that could introduce errors from external noise or objects.
3Adaptability or versatility
If the device uses a mutual capacitive type sensor array to simultaneously detect multiple touch positions, then the detection capability is improved, but the parasitic capacitance of each capacitor is more susceptible to environmental changes and wear
Solution Approach 1:
The patent applies segmentation by treating each capacitor in the mutual capacitive sensor array independently. The controller obtains and manages parasitic capacitance values for each individual capacitor separately, allowing for precise tracking of capacitance changes at each intersection of drive and sensor electrodes. This segmented approach enables accurate multi-touch detection by independently analyzing capacitance variations at multiple locations while compensating for local environmental effects and wear on each capacitor.
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 device correctly detects touching even when parasitic capacitance changes, preventing erroneous reference values from affecting the accuracy of touch detection.
Implementation Method 1
a touch panel (11) including a sensor array (14) and an operation surface (11a). The sensor array (14) includes drive electrodes (12) and sensor electrodes (13) overlapped with and insulated from the drive electrodes (12). The drive electrodes (12) and the sensor electrodes (13) are arranged in a grid pattern that forms capacitors C at intersections of the drive electrodes (12) and the sensor electrodes (13)
Implementation Method 2
set the reference value by obtaining a parasitic capacitance of each capacitor when the touch-type input device is activated
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A touch-type input device equipped with: a touch panel wherein multiple drive electrodes and multiple sensor electrodes are arranged in a grid-like pattern wherein capacitors are formed at the intersections between the drive electrodes and the sensor electrodes; and a controller that detects touch operations with respect to the operation surface of the touch panel. The controller determines whether a touch operation has occurred on the basis of a data group indicating the amount by which the electrostatic capacitance changes from a standard value that is set in advance for each capacitor. When activated the controller sets the standard value by acquiring the parasitic capacitance for each capacitor, and when it is determined on the basis of a range of variation (A) for the parasitic capacitance of the multiple capacitors that an erroneous standard value has been acquired, the parasitic capacitance is reacquired (S23).