Touch Panel Capacitance Compensation for Uniform Edge Sensitivity
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Solution Overview
Problem
Conventional touch display devices face issues with parasitic capacitance differences in metal touch sensors, leading to degraded touch sensitivity due to varying electrode patterns and lengths, which affect both active and non-active areas of the touch panel.
Innovation Solution
The implementation of a capacity compensation pattern that overlaps with outermost peripheral touch electrodes, with varying overlapping areas and widths, and the application of different voltages to these patterns, helps reduce parasitic capacitance differences by compensating for length and pattern-related capacitance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If touch electrodes and touch lines are arranged in a complex pattern to cover the display area, then touch sensing coverage is improved, but parasitic capacitance differences increase and touch sensitivity degrades
Solution Approach 1:
The patent applies different patterns and configurations to different regions of the touch panel. Specifically, touch electrodes in different areas (e.g., corner regions vs. center regions) are designed with different geometries and spacing to compensate for varying parasitic capacitance levels. This local differentiation allows each region to be optimized for its specific electrical characteristics while maintaining overall coverage.
Solution Approach 2:
The patent modifies electrical and geometric parameters of touch electrodes and touch lines to balance parasitic capacitance across the panel. This includes adjusting electrode width, length, spacing, and pattern density in different regions. By changing these parameters locally, the patent equalizes the total capacitance (parasitic + sensing) across all touch electrodes, thereby improving touch sensitivity uniformity.
2Adaptability or versatility
If touch lines are made longer to connect distant touch electrodes, then touch electrode connectivity is improved, but parasitic capacitance increases and touch sensitivity degrades
Solution Approach 1:
The patent designs touch lines with region-specific characteristics. Touch lines connecting electrodes in different areas have different widths, lengths, and routing paths optimized for their specific requirements. For example, touch lines in regions with higher parasitic capacitance may be made narrower or shorter, while those in low-capacitance regions can be more extensive, ensuring uniform overall performance.
Solution Approach 2:
The patent employs asymmetric touch line configurations where the geometry and routing of touch lines are deliberately made non-uniform across the panel. This asymmetry allows compensation for the varying parasitic capacitance contributions from different electrode positions and line lengths, balancing the total capacitance values across all touch electrodes despite differences in connectivity requirements.
3Area of stationary object
If electrode patterns are varied to optimize display area coverage, then display coverage is improved, but parasitic capacitance uniformity deteriorates
Solution Approach 1:
The patent implements location-dependent electrode patterns where the geometry, size, and arrangement of touch electrodes are specifically tailored to each region of the display. Corner electrodes, edge electrodes, and center electrodes all have different designs that account for their specific parasitic capacitance environments. This local optimization ensures that despite varying patterns across the display area, the resulting parasitic capacitance values are uniformized through careful parameter selection.
Solution Approach 2:
The patent systematically adjusts geometric parameters of electrode patterns (such as electrode area, perimeter, spacing, and shape factors) to compensate for position-dependent parasitic capacitance variations. By changing these parameters locally across the display area, the patent achieves uniform total capacitance values while maintaining comprehensive display coverage with optimized electrode distribution.
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 enhances touch sensitivity by stabilizing capacitance levels across the touch panel, regardless of electrode patterns and lengths, thereby improving the overall touch sensing performance in both active and non-active areas.
Implementation Method 1
a capacity compensation pattern COMP overlapping a partial area of a first outermost peripheral touch electrode TE1 and a partial area of a second outermost peripheral touch electrode TE2
Data Source
AI summary
A touch display device includes a plurality of touch electrodes and a plurality of touch lines electrically connected to at least some of the plurality of touch electrodes arranged on a touch panel and an outermost peripheral touch electrode located at an outermost peripheral region of the touch panel has an extension part; a touch circuit driving the touch panel and sensing a touch or a touch position; a capacity compensation pattern disposed at the touch panel and vertically overlapping the extension part of the outermost peripheral touch electrode, wherein the plurality of touch lines is located at an outside area of the capacity compensation pattern.