RC Matching in Touch Screen Sense Connections
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Solution Overview
Problem
Capacitive touch sensor panels face challenges in maintaining uniform resistances and capacitances across sense connections, affecting the transient operation and accuracy of touch event detection.
Innovation Solution
The implementation of various techniques to balance the resistances and capacitances of sense connections, including detour routing and dummy routing configurations, ensures that each sense connection presents a substantially equal load, thereby maintaining uniform transient operation across the touch screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sense connections are routed directly to touch pixels at different distances, then the touch screen can be manufactured with simpler routing, but the resistances and capacitances of sense connections become non-uniform across the touch screen
Solution Approach 1:
The patent applies preliminary action by adding dummy routing to sense connections before final connection to touch pixels. This preliminary extension equalizes the total length and electrical characteristics of all sense connections, ensuring uniform RC time constants across the touch screen while maintaining manufacturing simplicity.
Solution Approach 2:
The patent changes the physical parameter of sense connection length by adding dummy routing segments. This parameter modification equalizes the electrical characteristics (resistance and capacitance) of sense connections, transforming non-uniform connections into uniform ones without complicating the manufacturing process.
2Reliability
If sense connection lengths are equalized to balance loads, then uniform transient operation is achieved, but the routing complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies segmentation by dividing sense connections into functional segments: active routing segments that connect to touch pixels and dummy routing segments that extend length without functional connection. This segmentation allows equalization of total length while keeping the active routing simple and manageable.
Solution Approach 2:
The dummy routing acts as an intermediary element that mediates between the simple direct routing and the requirement for equal length. It provides the additional length needed for uniformity without interfering with the functional connection between sense connections and touch pixels.
3Ease of manufacture
If non-uniform sense connections are used, then manufacturing is simpler, but touch event detection accuracy decreases due to non-uniform RC time constants
Solution Approach 1:
The dummy routing is added in advance during manufacturing to pre-equalize the electrical characteristics of sense connections. This preliminary action ensures that all sense connections have uniform RC time constants before they are used for touch detection, thereby maintaining both manufacturing simplicity and detection accuracy.
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 ensures consistent and accurate detection of touch events by maintaining uniform RC time constants across the touch screen, enhancing the reliability and performance of capacitive touch sensor panels.
Implementation Method 1
the capacitances of these sense connections to be substantially uniform across the touch screen so that transient operation of the sense connections can be substantially uniform
Implementation Method 2
the resistances and/or capacitances of these sense connections to be substantially uniform across the touch screen
Data Source
AI summary
A touch screen. In some examples, the touch screen can comprise a first element coupled to a first sense connection, and a second element coupled to a second sense connection. In some examples, the first and second sense connections can be configured such that a load presented by the first sense connection and the first element is substantially equal to a load presented by the second sense connection and the second element. In some examples, the first and second sense connections can comprise detour routing configured such that a resistance of the first sense connection is substantially equal to a resistance of the second sense connection. In some examples, the first and second sense connections can be coupled to dummy routing configured such that a first capacitance presented by the first sense connection is substantially equal to a second capacitance presented by the second sense connection.