Capacitive Touch Panel Heat Correction via Coupled Electrodes
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Solution Overview
Problem
Touch panels struggle to accurately detect the position and pressure of a finger while minimizing the influence of finger heat and ambient heat, as existing technologies using pyroelectric bodies can erroneously detect heat-generating objects and fail to differentiate between finger and ambient temperatures.
Innovation Solution
A capacitive touch panel system with a controller that includes drive electrodes, position detection electrodes, pressure detection electrodes, and heat detection electrodes, where the controller provides drive signals and corrects pressure detection signals using heat detection signals from a change in coupling capacitance between heat detection and pressure detection electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pyroelectric body is used to detect finger approach, then the touch panel can detect the position of the finger, but the touch panel may erroneously detect heat-generating objects other than fingers as finger approach
Solution Approach 1:
The patent segments the detection function into multiple independent electrode types: position detection electrodes, pressure detection electrodes, and heat detection electrodes. Each electrode type is responsible for a specific detection function, allowing the system to differentiate between finger position, applied pressure, and heat sources separately, thereby reducing erroneous detections
Solution Approach 2:
The patent introduces heat detection electrodes as intermediary sensors that specifically detect thermal changes. By using these intermediary heat-sensing elements, the system can identify and filter out false positives from heat-generating objects, preventing them from being misinterpreted as finger approach events
2Measurement precision
If a pyroelectric body is used to detect finger approach, then the touch panel can detect position, but if the temperatures of the pyroelectric body and finger are almost the same, it is difficult to obtain the pyroelectric effect
Solution Approach 1:
The patent replaces the pyroelectric detection mechanism with a capacitive detection system using conductive electrodes. Instead of relying on temperature differences to generate pyroelectric effects, the system uses capacitive coupling between the finger and electrodes to detect position and pressure, eliminating the temperature difference requirement
Solution Approach 2:
The patent changes the detection parameter from thermal response (pyroelectric effect requiring temperature difference) to electrical capacitance response. By measuring capacitance changes between electrodes and the finger, the system can detect finger position and pressure without requiring temperature differences, thus removing the harmful constraint
3Measurement precision
If heat detection electrodes are added to correct pressure detection signals, then the influence of finger heat and ambient heat is reduced, but the device complexity increases
Solution Approach 1:
The patent designs the heat detection electrodes to serve multiple functions: they detect heat for signal correction, they provide capacitive coupling for position detection, and they work in conjunction with pressure detection electrodes. This multi-functionality reduces the need for separate dedicated components, mitigating the increase in device complexity
Solution Approach 2:
The patent merges the heat detection function with the existing capacitive touch detection structure. The heat detection electrodes are integrated into the same substrate and work in combination with position and pressure detection electrodes, creating a unified multi-functional electrode system rather than adding completely separate detection mechanisms
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 system effectively reduces the influence of finger heat and ambient heat, enabling accurate detection of finger position and pressure without relying on pyroelectric bodies, improving detection accuracy and reducing erroneous readings.
Implementation Method 1
a heat detection signal obtained from a change in a coupling capacitance between the heat detection electrode adjacent to the pressure detection electrode and the pressure detection electrode
Data Source
AI summary
A touch panel system includes a capacitive touch panel and a controller that controls the touch panel. The touch panel includes drive electrodes and floating island electrodes located on a first substrate and position detection electrodes, pressure detection electrodes, and heat detection electrodes located on a second substrate. The drive electrode overlaps at least part of the heat detection electrode and at least part of the pressure detection electrode, and the floating island electrode overlaps at least part of the position detection electrode in plan view. The controller provides a drive signal to the drive electrodes and the heat detection electrodes and corrects a pressure detection signal obtained from each of the pressure detection electrodes by using a heat detection signal obtained from a change in a coupling capacitance between the pressure detection electrode and the heat detection electrode.