Tuning Sense Connection RC Time Constants
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Solution Overview
Problem
Capacitive touch sensor panels face challenges in tuning the resistances and capacitances of sense connections to achieve desired bandwidth parameters for transient operation, affecting the accuracy and efficiency of touch event detection.
Innovation Solution
The implementation of various techniques for tuning the resistances and capacitances of sense connections, including configurations such as semi-RC matching, where sense connections with different numbers of traces are optimized to have equal RC time constants, and decoupling excess trace portions to reduce capacitive load, ensuring consistent and improved bandwidth across the touch screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sense connections use more traces to reduce resistance, then electrical conductivity improves, but capacitive load increases affecting bandwidth
Solution Approach 1:
The patent applies parameter changes by varying the number of traces in sense connections based on their position on the touch panel. Connections farther from the driver circuit use more traces to compensate for higher resistance, while closer connections use fewer traces. This positional parameter adjustment optimizes the balance between resistance and capacitive load, achieving consistent RC time constants across the panel and improving touch detection accuracy without excessive capacitive loading.
2Area of stationary object
If sense connections are made longer to reach distant electrodes, then coverage area improves, but RC time constant varies affecting bandwidth consistency
Solution Approach 1:
The patent implements local quality by making sense connections heterogeneous in their trace configuration based on position. Rather than using uniform trace configurations throughout the panel, the design assigns different numbers of traces to different regions - with connections to distant electrodes using more traces and connections to nearby electrodes using fewer traces. This local differentiation compensates for position-dependent resistance variations, achieving consistent RC time constants and bandwidth across the entire touch panel area.
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
These techniques enhance the accuracy and efficiency of touch event detection by ensuring consistent RC time constants and reduced capacitive load, thereby improving the overall performance of capacitive touch sensor panels.
Implementation Method 1
the resistances and/or capacitances of sense connections can be tuned such that transient operation of the sense connections (e.g., their bandwidths) can achieve desired parameters
Implementation Method 2
the resistances and/or capacitances of sense connections can be tuned such that transient operation of the sense connections (e.g., their bandwidths) can achieve desired parameters
Implementation Method 3
sense connections with different numbers of traces are optimized to have equal RC time constants
Data Source
AI summary
A touch sensor panel comprising a first touch node electrode of a plurality of touch node electrodes, the first touch node electrode coupled to a first sense connection comprising a first set of traces, the first sense connection configured to have a first resistance per unit length that varies along a length of the first sense connection, and a second touch node electrode of the plurality of touch node electrodes, the second touch node electrode coupled to a second sense connection comprising a second set of traces, the second sense connection configured to have a second resistance per unit length that varies along a length of the second sense connection differently than the first resistance per unit length varies along the length of the first sense connection. An effective resistance of the first sense connection and the second sense connection are equal.