Capacitive Touch Panel Hierarchical Scanning for Resolution
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Solution Overview
Problem
Conventional capacitive touch panels in display devices face challenges such as low resolution, inability to detect small contact areas, and issues with parasitic capacitors and noise, which limit their integration and performance in flat display devices like LCDs.
Innovation Solution
A capacitive touch panel system utilizing a two-stage scanning mechanism, where the first stage scans large areas and the second stage focuses on smaller areas, incorporating a processing circuit, first scanning circuit, and second scanning circuit to generate input signals based on capacitance changes, effectively addressing the limitations of parasitic capacitors and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a capacitive touch panel is used in a flat display device, then the device can have a thin structure, but the resolution and detection accuracy of touch input are reduced
Solution Approach 1:
The capacitive touch panel is divided into multiple capacitor groups, each containing multiple capacitor modules. The first scanning circuit scans capacitor groups in turn, while the second scanning circuit scans capacitor modules within selected groups. This segmentation allows the system to maintain a thin structure while improving touch detection resolution through hierarchical scanning of divided regions.
2Volume of moving object
If a capacitive touch panel is used in a flat display device, then the device can be more compact, but parasitic capacitors and noises interfere with detection accuracy
Solution Approach 1:
The patent extracts and isolates parasitic capacitors from the detection system by using a two-stage scanning approach. The first stage identifies capacitor groups with abnormal capacitance changes, and the second stage focuses on specific capacitor modules within those groups. This extraction process separates the signal from noise, allowing the system to ignore parasitic capacitors and external noises that would otherwise interfere with touch detection accuracy.
Solution Approach 2:
The processing circuit acts as an intermediary between the capacitive touch panel and the control system. It processes capacitance measurements from multiple capacitor modules, compares them against threshold values, and generates touch input signals only when genuine touch conditions are detected. This intermediary processing filters out parasitic capacitors and noises, ensuring accurate touch recognition despite the thin structure of flat display devices.
3Device complexity
If line-by-line scanning is used in a capacitive touch panel, then the scanning process is simple, but the frequency limitation prevents its use in flat display devices
Solution Approach 1:
The scanning process is segmented into two stages: first scanning capacitor groups in turn, then scanning specific capacitor modules within selected groups. This segmentation enables the system to operate at higher frequencies suitable for flat display devices while maintaining manageable complexity through structured, hierarchical scanning of divided regions.
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
Enhances the resolution and accuracy of touch input detection, allowing for the integration of capacitive touch panels in display devices without increasing thickness and mitigating noise and parasitic capacitor-related issues.
Implementation Method 1
The touch panel includes a plurality of capacitor groups, and each group includes a number of capacitor modules... the processing circuit generates an input signal associated with a touching position on the touch panel... the measured capacitance of the specific capacitor module, when being touched by user, is greater than a predetermine capacitance
Data Source
AI summary
The present invention provides an image display system including a capacitive touch panel. The touch panel includes a plurality of groups of capacitor, and each group includes a number of capacitor modules. The touch panel also includes a processing circuit, a first scanning circuit, and a second scanning circuit. The first scanning circuit scans in turn each group. The second scanning circuit scans in turn each capacitor module of a particular group of capacitor. Then the processing circuit generates an input signal associated with a position on the touch panel.