Integrated Touchscreen Circuitry for Low-Parasitic Touch and Light Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive touch sensor panels in electronic devices often experience errors due to parasitic or stray capacitances between touch node electrodes and other components, which can lead to inaccurate touch detection and increased noise in sensing outputs.
Innovation Solution
The integration of micro circuitry in touch screens that includes light emitting diodes (LEDs) or organic light emitting diodes (OLEDs) and chiplets, configured to perform both touch and optical sensing, with electrodes acting as both display and touch functionality nodes, allows for concurrent touch and optical sensing by forming touch node electrodes from groups of electrodes and sensing capacitance and ambient light simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive touch sensor panels use transparent conductive plates for touch sensing, then touch detection capability is achieved, but parasitic capacitances between touch node electrodes and other components cause errors and noise in sensing outputs
Solution Approach 1:
The patent extracts and removes parasitic capacitance sources by reconfiguring the electrode connections. Specifically, it separates the touch sensing function from display electrodes by using dedicated touch electrodes that are electrically isolated from display circuitry, thereby eliminating the parasitic capacitances that would otherwise couple touch sensing signals to display ground references.
Solution Approach 2:
The patent segments the electrode system into distinct functional groups: display electrodes for light emission and dedicated touch electrodes for sensing. This segmentation allows independent optimization of each function and prevents the parasitic coupling that occurs when the same electrodes serve both display and touch functions.
2Device complexity
If touch sensing circuitry is integrated into display pixel stackup, then device complexity is reduced, but parasitic capacitances between touch nodes and other components increase
Solution Approach 1:
The patent segments the integrated circuit system into distinct functional blocks: display driving circuitry, touch sensing circuitry, and their interconnections. This segmentation within the integrated architecture allows touch sensing nodes to be electrically isolated from display circuit ground references, reducing stray capacitances while maintaining integration benefits.
Solution Approach 2:
The patent introduces intermediary structures such as guard rings and isolation trenches between touch sensing nodes and display circuitry in the integrated stackup. These intermediaries act as electrical barriers that reduce parasitic capacitance coupling while allowing the system to remain integrated at the substrate level.
3Ease of manufacture
If the same electrodes are used for both display and touch functionality, then manufacturing complexity is reduced, but touch sensing precision deteriorates due to parasitic effects
Solution Approach 1:
The patent segments the electrode system into separate display electrodes and touch electrodes, even though both may be formed from the same transparent conductive material layers. This segmentation is achieved through different electrode patterns and electrical connections, allowing each function to be optimized independently while using the same manufacturing process for the conductive layers.
Solution Approach 2:
The patent uses universal transparent conductive oxide (TCO) layers that can be patterned to serve different functions. The same TCO material and deposition processes are used for both display electrodes and touch electrodes, maintaining manufacturing simplicity while achieving functional separation through clever electrode design and connection schemes.
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 configuration reduces parasitic capacitances, improves touch sensing accuracy, and enables parallel capture of touch and ambient light information, enhancing the reliability and precision of touch inputs in electronic devices.
Implementation Method 1
A touch screen, such as an integrated touch screen, can include light emitting diodes or organic light emitting diodes (LEDs/OLEDs)
Implementation Method 2
light emitting diodes or organic light emitting diodes (LEDs/OLEDs)
Implementation Method 3
Capacitive touch sensor panels can be formed by a matrix of transparent, semi-transparent or non-transparent conductive plates
Implementation Method 4
the chiplets can be further configured to perform optical sensing using some of the touch sensing circuitry
Data Source
AI summary
An electronic device can include integrated micro circuitry configurable for optical sensing and touch and/or proximity sensing. An integrated touch screen can include light emitting diodes or organic light emitting diodes and chiplets. In some examples, the LEDs/OLEDs and chiplets can be disposed in a visible area of the integrated touch screen. In some examples, some or all of the chiplets can be disposed outside of the visible area of the integrated touch screen. In some examples, the chiplets can include display driving circuitry and touch sensing circuitry, and can optionally perform optical sensing using the touch sensing circuitry. In some examples, the chiplets can include separate touch chiplets configured to perform touch sensing (and/or optical sensing) and display chiplets configured to perform display functionality (and optionally provide some switching functionality).