Self-Capacitance Touch Pixel Driving for Floating Ground Stability
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Solution Overview
Problem
Capacitive touch sensor panels often experience undesirable changes in touch sensing signals due to floating ground references, which can lead to inaccurate touch sensing results and reduced performance.
Innovation Solution
Implementing techniques such as driving and sensing one or more touch pixels while coupling others to a reference voltage, configuring routing to reduce parasitic capacitances, and utilizing specific touch pixel driving schemes to mitigate the effects of floating ground references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a floating ground reference is used in touch sensing circuitry, then device complexity is reduced, but measurement precision deteriorates due to undesirable changes in touch sensing signals
Solution Approach 1:
The patent introduces an intermediary mechanism (capacitive coupling and differential sensing) between the floating ground reference and the touch sensing signals. This intermediary approach allows the system to maintain a simple floating ground configuration while isolating the sensing circuitry from ground potential fluctuations, thereby preserving measurement precision without increasing device complexity
Solution Approach 2:
The patent changes the operating parameters of the sensing circuitry by using differential voltage measurements and capacitive coupling techniques. This allows the system to operate effectively with a floating ground reference by measuring voltage differences rather than absolute voltages, thus maintaining measurement precision while keeping the ground reference configuration simple
2Measurement precision
If routing is configured to reduce parasitic capacitances, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies local quality optimization by specifically designing the routing configuration in critical areas where parasitic capacitances have the greatest impact on sensing accuracy. Rather than optimizing the entire routing system uniformly, the patent focuses on local routing adjustments near the touch sensing electrodes and signal paths, thereby improving measurement precision with minimal increase in overall device 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
These techniques enhance the accuracy and reliability of touch sensing by stabilizing the ground reference and minimizing parasitic capacitance effects, thereby improving the overall performance of the touch screen system.
Implementation Method 1
Touch events can be sensed on the above touch sensor panels by detecting changes in the self-capacitance of the conductive plates
Implementation Method 2
fringing electrical fields used to detect touch can extend beyond the surface of the display, and objects approaching near the surface may be detected near the surface without actually touching the surface
Data Source
AI summary
A touch controller is disclosed. In some examples, the touch controller can include sense circuitry configured to be coupled to a first touch pixel and a second touch pixel on a touch sensor panel. In some examples, the sense circuitry can be configured to drive and sense the first touch pixel during a first time period while coupling the second touch pixel to a reference voltage. In some examples, the sense circuitry can be configured to drive and sense the second touch pixel during a second time period while coupling the first touch pixel to the reference voltage. In some examples, the reference voltage can be a system ground of the touch controller. In some examples, the sense circuitry can be configured to drive and sense pluralities of touch pixels in a similar manner.