Flexible Touch Sensing Architecture With Pixel Mux Switching
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Solution Overview
Problem
Existing touch screen technologies face challenges in implementing flexible and space-efficient architectures that can accommodate various types of scans, particularly for capacitive touch sensor panels with a large number of conductive plates, which complicates the routing of touch node electrodes to sense circuitry.
Innovation Solution
The proposed solution involves a flexible touch and/or pen sensing system architecture that integrates self-capacitance and mutual capacitance sensing, utilizing a matrix of conductive plates made of materials like Indium Tin Oxide (ITO) and incorporating touch sensing circuitry into the display pixel stackup, with innovative electrode routing configurations and switching circuits to reduce the number of interconnect lines and enhance scanning efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a matrix of conductive plates is used to form capacitive touch sensor panels, then transparency and touch sensitivity are improved, but the number of interconnect lines required increases, leading to increased device complexity and manufacturing difficulty
Solution Approach 1:
The patent combines self-capacitance and mutual capacitance sensing into a single integrated system. The same matrix of conductive plates serves dual purposes: detecting self-capacitance changes for touch events and measuring mutual capacitance between plates. This merging eliminates the need for separate sensing systems and reduces interconnect line requirements while maintaining comprehensive touch detection capability.
Solution Approach 2:
The conductive plates in the matrix are designed to perform multiple functions simultaneously. Each plate can act as both a sensing element for self-capacitance measurements and as part of a capacitive couple for mutual capacitance measurements. The switching circuitry enables these plates to be selectively configured for different scan types, maximizing their utility and reducing the overall system complexity.
2Area of stationary object
If touch sensing circuitry is integrated into the display pixel stackup, then space efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The touch sensing circuitry is nested within the existing display pixel stackup structure. The conductive plates and switching elements are incorporated into the same layered architecture as the display pixels, with the touch sensing components embedded between or alongside the display layers. This nesting approach maximizes space utilization while leveraging the existing manufacturing processes and precision tolerances of the display fabrication.
3Device complexity
If switching circuits are used to reduce the number of interconnect lines, then device complexity is reduced, but the number of switches required increases, potentially increasing manufacturing complexity
Solution Approach 1:
The switching circuits utilize thin-film transistor (TFT) technology with configurable threshold voltages and channel widths. By adjusting these electrical and geometric parameters, the switches can be optimized for low on-resistance and high off-state isolation without requiring complex fabrication steps. The same TFT process used for display pixel control is leveraged for the switching functions, simplifying manufacturing.
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 allows for efficient implementation of different scan types on touch screens with a large number of conductive plates, reducing the complexity and cost of manufacturing while maintaining effective touch detection and recognition capabilities.
Implementation Method 1
capacitive touch sensor panels can be formed by a matrix of substantially transparent or non-transparent conductive plates
Data Source
AI summary
A switching circuit is disclosed. The switching circuit can comprise a plurality of pixel mux blocks, each of the pixel mux blocks configured to be coupled to a respective touch node electrode on a touch sensor panel, and each of the pixel mux blocks including logic circuitry. The switching circuit can also comprise a plurality of signal lines configured to be coupled to sense circuitry, at least one of the signal lines configured to transmit a touch signal from one of the respective touch node electrodes to the sense circuitry. The logic circuitry in each pixel mux block of the plurality of pixel mux blocks can be configured to control the respective pixel mux block so as to selectively couple the respective pixel mux block to any one of the plurality of signal lines.