Touch Panel Calibration Using Parasitic Capacitance Variation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch detection devices for capacitance-type touch panels perform calibration unnecessarily, leading to incorrect capacitance detection when conductive materials are temporarily placed near the panel, and current calibration methods fail to distinguish appropriate calibration situations.
Innovation Solution
A touch detection device that adjusts the capacitance measurement range based on the level and variation of base capacitances, performing calibration only when significant changes occur and variation is minimal, using indices like sum, difference, or averages of capacitances to determine appropriate calibration times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If calibration is performed every time the touch detection device is activated, then the measurement range can be adjusted to accommodate capacitance changes, but the calibration process becomes redundant and increases system complexity when base capacitances have not changed significantly
Solution Approach 1:
The system performs preliminary calibration at device activation to establish baseline capacitance values. However, it uses these baseline values to determine whether full recalibration is actually needed, thereby performing calibration action only when necessary rather than automatically every time the device is activated.
Solution Approach 2:
The system continuously monitors capacitance values and compares changes against threshold criteria. This feedback mechanism allows the system to dynamically determine whether recalibration is needed based on actual capacitance drift, eliminating redundant calibration operations while maintaining detection accuracy.
2Adaptability or versatility
If the measurement range is set wide to include expected capacitance change range, then capacitance detection can accommodate variations, but the system cannot distinguish between temporary conductive material placement and permanent base capacitance changes
Solution Approach 1:
The system dynamically adjusts the measurement range based on monitored capacitance changes. When capacitance drift exceeds thresholds indicating permanent changes, the system expands the measurement range accordingly. This dynamic adaptation allows the system to maintain precision by only expanding the range when necessary, rather than using a permanently wide range that would mask temporary conductive material placement.
3Reliability
If calibration is performed when base capacitances change due to temporary conductive material placement, then the measurement range can be adjusted, but the calibration becomes inappropriate and may prevent correct detection after the conductive material is removed
Solution Approach 1:
The system uses feedback monitoring to distinguish between temporary and permanent capacitance changes. By continuously comparing capacitance values against baseline and threshold criteria, the system can detect when changes are due to temporary conductive material placement versus permanent base capacitance changes, and only performs calibration when permanent changes are confirmed.
Solution Approach 2:
The system performs preliminary assessment of capacitance changes against predefined thresholds before initiating calibration. This preliminary action filters out false calibration triggers caused by temporary conductive material placement, ensuring that calibration only occurs when permanent base capacitance changes are detected.
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
Ensures accurate capacitance detection by performing calibration only when necessary, preventing false triggers from temporary conductive material placement and maintaining reliable touch detection.
Implementation Method 1
a touch detection circuit configured to detect a capacitance of each of a plurality of points on the touch panel
Data Source
AI summary
“A touch detection device, a touch panel device, and a touch detection device calibration method” for performing calibration in a situation where performing calibration is appropriate are provided. With a detected capacitance of each electrode regarded as a parasitic capacitance of the electrode, when a sum of amounts of changes in the parasitic capacitances of electrodes is greater than a predetermined threshold value and a variation index value indicating the magnitude of variation in the parasitic capacitances of the electrodes is less than a predetermined threshold value, a calibration controller calibrates each detection circuit of a sense block so as to detect the capacitance of each electrode while setting the parasitic capacitance of the electrode at a center level.