Touch Sensor Routing Trace Crosstalk Compensation
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Solution Overview
Problem
Capacitive touch sensor panels face issues with crosstalk between routing traces and user interactions, leading to inaccurate touch detection and positioning due to capacitive coupling between the user's grip and edge routing traces.
Innovation Solution
The implementation of compensation traces in the border region of the touch sensor panel and the use of shielding electrodes near routing traces, along with a matrix compensation technique that can be applied globally or based on detected touch locations, to mitigate crosstalk effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If routing traces are placed at the edge of the touch sensor panel, then signal routing is achieved, but capacitive coupling with user's grip causes crosstalk interference
Solution Approach 1:
Compensation traces are introduced as intermediary elements between the routing traces and the user's grip. These compensation traces are electrically connected to sensing circuitry and are used to measure and compensate for the capacitive coupling effects, effectively mediating the harmful interaction between the routing traces and the user's hand
Solution Approach 2:
The system uses compensation traces to continuously monitor capacitive coupling effects and provides feedback to the sensing circuitry. This feedback mechanism allows the system to dynamically adjust and compensate for crosstalk interference in real-time, maintaining accurate touch detection despite the presence of routing traces at the panel edges
2Measurement precision
If compensation traces are added to border region, then crosstalk compensation is improved, but device complexity increases
Solution Approach 1:
The compensation system is segmented into separate compensation traces that are electrically disconnected from the main routing segments. This segmentation allows the compensation function to be isolated and implemented independently, reducing the impact on overall device complexity while maintaining improvement in measurement precision
Solution Approach 2:
Compensation traces create a simplified copy or representation of the routing trace geometry in the border region. By copying the essential capacitive coupling characteristics without replicating the full routing functionality, the system achieves compensation with minimal additional complexity
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 solution effectively reduces crosstalk interference, improving the accuracy of touch detection and positioning by compensating for the capacitive coupling between the user's grip and routing traces, thereby enhancing the overall performance of capacitive touch sensor panels.
Implementation Method 1
capacitive coupling between the user's grip and edge routing traces
Implementation Method 2
fringing electrical fields used to detect touch can extend beyond the surface of the display
Implementation Method 3
shielding electrodes can be added near routing traces to ensure that edge routing traces have equal spacing to an adjacent trace
Data Source
AI summary
Errors in touch signals due to grip and finger coupling to routing traces can be compensated. In some examples, reference traces can be provided to measure a signal contribution from a user's grip to routing traces. In some examples, shielding electrodes can be provided to reduce fringing field coupling between a user's grip and routing traces that are missing a neighboring trace. In some examples, a global correction for finger to trace coupling can be performed based on stored matrices that characterize cross-coupling between touch sensor electrodes in a touch sensor electrode array. In some examples, a determined touch location can be used to apply localized matrix correction to a subset of touch sensor electrodes in the touch sensor electrode array. In some examples, correction for multiple touch locations can be corrected in a specified order to avoid compensating for crosstalk effects of a single touch sensor electrode multiple times.