Capacitance Touch Panel Edge Detection Using Peripheral Electrode Accumulation
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Solution Overview
Problem
Capacitance type touch panels face precision degradation in touch detection, especially near the edges, due to the smaller contact area and amplified noise from drive signals, leading to reduced accuracy in detecting finger or stylus inputs.
Innovation Solution
An input apparatus with a touch panel sensor featuring self-capacitance and mutual-capacitance measurements, where peripheral electrodes' measurements are used to determine the accumulation numbers for intersection points, adjusting these numbers based on the proximity of the conductor object to improve detection precision near the edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current mirror circuit is used to amplify the detected signal of the touch panel, then the precision of touch detection is improved, but noise from the drive signal is also amplified, degrading the precision of touch detection
Solution Approach 1:
The invention divides the touch panel electrodes into two distinct groups: peripheral electrodes and internal electrodes. Each group is measured using different methods (self-capacitance for peripheral, mutual-capacitance for internal), allowing the system to handle edge detections separately from center detections, thus avoiding noise amplification issues in the current mirror circuit while maintaining precision improvement.
Solution Approach 2:
Different measurement strategies are applied to different regions of the touch panel. Peripheral electrodes use self-capacitance measurement with threshold-based determination, while internal electrodes use mutual-capacitance measurement with accumulation numbers. This localized approach optimizes precision for each region without suffering from the noise amplification problem that affects the entire panel when using current mirror circuits globally.
2Adaptability or versatility
If the contact area of a finger is smaller near the edge of the touch panel, then the touch detection precision for edge electrodes is degraded, but the overall touch panel functionality is maintained
Solution Approach 1:
The system performs a preliminary self-capacitance measurement on peripheral electrodes before conducting the main mutual-capacitance measurement. This preliminary action identifies potential touch events at the edges, allowing the system to then apply appropriate accumulation numbers in the subsequent mutual-capacitance measurement to enhance precision for those specific edge regions.
Solution Approach 2:
The invention changes the measurement parameters dynamically based on electrode location and touch detection needs. Accumulation numbers are adjusted according to the measured self-capacitance values and the position of intersection points relative to detected conductor objects. This parameter adaptation allows the system to maintain high precision for edge touches with smaller contact areas while preserving overall touch panel functionality.
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 precision of touch detection near the edges of the touch panel without compromising usability, maintaining consistent response times and accuracy across the entire panel surface.
Implementation Method 1
a coordinate touched by a finger, a stylus pen or the like is specified based on a static capacitance between a plurality of column electrodes arranged in a column direction and a plurality of row electrodes arranged in a row direction
Data Source
AI summary
A setting unit sets, if any measurement result of peripheral electrodes exceeds a threshold value, an accumulation number of each mutual-capacitance of intersection points, so that the accumulation number of an intersection point closer to a position of a conductor object is larger, and the accumulation number of an intersection point farther from the position of the conductor object is smaller. A setting unit sets, if all of the measurement results do not exceed the threshold value, the accumulation numbers of intersection points to be the same value.