Capacitive Touch Panel Noise Correction via Reference Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing coordinate input devices with capacitive coupling type touch panels face challenges in maintaining high detection precision due to random noise incorporation from the display panel, which degrades the accuracy of capacitance detection and input coordinate precision.
Innovation Solution
The implementation of a selective electrode drive circuit and capacitance detection circuit that selectively applies drive signals to electrodes and uses reference electrodes to isolate noise from the display panel, allowing for noise cancellation and enhanced capacitance detection precision by using the capacitance detection circuit to generate digital output signals and correct noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a capacitive coupling type touch panel is used to maintain high transmittance and display image quality, then display image quality is improved, but random noise from the display panel degrades capacitance detection precision
Solution Approach 1:
The patent introduces a noise correction mechanism that acts as an intermediary between the noisy capacitance detection signal and the final coordinate determination. A noise correction value is calculated based on capacitance values from non-selected electrodes and used to correct the detection signal, thereby mediating the harmful noise while preserving the useful detection capability
Solution Approach 2:
The patent implements a feedback mechanism where the noise correction value is continuously calculated and applied to correct subsequent capacitance detection signals. The correction process uses feedback from the detected noise characteristics to dynamically adjust and eliminate noise components, improving detection precision while maintaining display quality
2Ease of operation
If capacitance detection is performed by detecting current flow through intersection capacitance, then coordinate detection function is achieved, but random noise from display panel incorporates into detection signal
Solution Approach 1:
The patent extracts and separates the noise component from the capacitance detection signal by detecting capacitance values from non-selected electrodes that are affected only by noise. This extracted noise information is then used to remove the harmful noise component from the main detection signal, preserving the coordinate detection function while eliminating noise interference
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
This approach effectively reduces random noise from the display panel, improving the accuracy of capacitance detection and input coordinate precision, enabling more reliable touch input operations without degrading display image quality.
Implementation Method 1
a capacitive coupling type that detects a change in capacitance
Implementation Method 2
detecting a current flowing via the capacitance in the vicinity of an intersection between the row wire to which the drive signal is applied and the column wire
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is a coordinate input device including: a coordinate input unit (101) having a plurality of first detection electrodes (X_SENS) and a plurality of second detection electrodes (Y_SENS); an electrode drive circuit (102) that applies a drive signal to one or more of the detection electrodes; a capacitance detection circuit (103) that detects a capacitance of the first and/or second detection electrode; means for selecting one or more of the detection electrodes to which the drive signal is not applied from among the detection electrodes which are disposed in parallel to the detection electrodes to which the drive signal is applied, as a reference electrode; means for detecting a capacitance of the selected reference electrode; means for correcting a capacitance detection result of the capacitance detection circuit on the basis of the detected capacitance of the reference electrode; and an input coordinate computing circuit (104) that calculates an input coordinate from the corrected capacitance detection result.