Touch Panel Compensation Structure for Parasitic Capacitance Balance
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Solution Overview
Problem
Conventional touch display devices experience issues with parasitic capacitance differences due to varying electrode patterns and lengths of touch lines, leading to degraded touch sensitivity.
Innovation Solution
A parasitic capacitance difference reducing structure is implemented by using a capacity compensation pattern that overlaps partial areas of outermost peripheral touch electrodes, with varying overlapping sizes and lengths of touch lines, and applying ground or different voltage levels to the compensation pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If touch electrodes and touch lines are arranged in various patterns to cover the display area, then touch sensing coverage is improved, but parasitic capacitance differences increase due to varying line lengths and electrode configurations
Solution Approach 1:
The patent applies different capacitance compensation values to different touch electrodes based on their local characteristics. Touch electrodes connected to longer touch lines or located in regions with higher parasitic capacitance are assigned larger compensation values, while those with shorter lines receive smaller compensation values. This localized differentiation compensates for the parasitic capacitance differences caused by varying line lengths and electrode patterns, thereby maintaining uniform touch sensitivity across the entire display area.
2Reliability
If touch lines are extended to connect outermost peripheral touch electrodes, then electrode connectivity is improved, but parasitic capacitance increases due to longer line lengths
Solution Approach 1:
The patent changes the capacitance parameter of touch electrodes by adding capacitance compensation values. For touch electrodes connected to longer touch lines, larger capacitance compensation values are added to offset the increased parasitic capacitance. This parameter adjustment ensures that the total capacitance (sensing capacitance plus parasitic capacitance plus compensation capacitance) remains consistent across all touch electrodes, thereby maintaining reliable connectivity while compensating for the harmful effect of extended line lengths.
3Area of stationary object
If electrode patterns are optimized for display area coverage, then display integration is improved, but parasitic capacitance differences increase affecting touch accuracy
Solution Approach 1:
The patent implements a feedback mechanism where the system pre-calculates and stores capacitance compensation values for each touch electrode based on its position and connected touch line length. During touch detection, the appropriate compensation value is retrieved and applied to each touch electrode's capacitance measurement. This feedback-based compensation corrects the detection results to account for parasitic capacitance differences, thereby maintaining high touch detection accuracy despite variations in electrode patterns required for display area coverage.
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 structure effectively reduces parasitic capacitance differences, enhancing touch sensitivity and accuracy regardless of electrode patterns and line lengths, both in active and non-active areas.
Implementation Method 1
a capacity compensation pattern COMP overlapping a partial area of a first outermost peripheral touch electrode TE and a partial area of a second outermost peripheral touch electrode TE
Implementation Method 2
there is a problem in that unnecessary parasitic capacitance can be incurred according to the electrode pattern structure of a touch panel
Data Source
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AI summary
Disclosed is a touch display device and a touch panel (TSP) that have a structure employing an extension part (EP) at an outermost touch electrode (O-TE), such that it can reduce the difference of parasitic capacitances, which occur in metal touch sensors. According to the present disclosure, touch sensitivity can be improved through parasitic capacitance difference reduction of touch electrodes (TE) and touch lines (TL).