Touch Display Crosstalk Mitigation via Luminance Compensation

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Solution Overview

Problem

Existing electronic devices with integrated display and touch subsystems face crosstalk issues, particularly impedance-based display-touch crosstalk (Impedance DTX), which affects touch sensing accuracy and user experience.

Innovation Solution

A system and method that mitigate Impedance DTX by determining cathode impedance during touch scans, using image processing to calculate pixel luminance values, and transmitting these values along with a global brightness value to the touch processing system to estimate and cancel out the undesired Impedance DTX component.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If display and touch subsystems are integrated in the same panel, then device complexity is reduced and manufacturing is simplified, but crosstalk between subsystems occurs causing touch sensing inaccuracy

Engineering Contradiction:

Improvesystem integration complexityVSAvoidtouch sensing accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the touch sensing operation into multiple phases: a first phase for charging the sensing capacitance and a second phase for sensing the touch signal. This temporal segmentation allows the system to separate touch sensing from display operation, reducing crosstalk while maintaining integration benefits

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary charging of the sensing capacitance during the first phase before the actual touch sensing occurs in the second phase. This preliminary action prepares the system for accurate touch detection while isolating the sensing operation from display-induced impedance variations

Inventive Principle:

Principle #10Preliminary action

2Speed

If touch sensing operates during display image presentation, then real-time touch response is achieved, but impedance variations from display content modulate touch scan data causing crosstalk

Engineering Contradiction:

Improvetouch response speedVSAvoidtouch scan data accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The patent implements periodic touch scanning during display operation, where touch sensing is performed at specific intervals (during vertical blanking periods or designated time slots) rather than continuously. This periodic approach maintains real-time responsiveness while minimizing interference from display content

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent uses feedback from image statistics (such as average pixel luminance or APL values) to dynamically adjust touch sensing parameters or compensate for impedance variations. This feedback mechanism allows the system to maintain accuracy despite ongoing display operation

Inventive Principle:

Principle #23Feedback

3Speed

If touch scan frequency is increased to improve responsiveness, then touch detection speed increases, but power consumption increases and crosstalk interference worsens

Engineering Contradiction:

Improvetouch detection speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic touch scanning at optimized frequencies that balance responsiveness with power efficiency. By scanning at lower frequencies during stable display periods and increasing frequency only when needed, the system reduces overall power consumption while maintaining adequate touch detection speed

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent creates an electrically quiet environment for touch sensing by performing scans during display blanking periods or using differential sensing techniques that cancel out common-mode interference. This inert sensing environment reduces noise without requiring increased scan frequency

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

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

The solution effectively compensates for Impedance DTX, improving touch processing subsystem performance, reducing power consumption, and enhancing user experience by minimizing inaccurate touch sensing operations.

Implementation Method 1

a touch sensing system may determine cathode impedance during a touch scan

Methodology Applied

Scientific EffectImpedance measurement: Electrical Resistance

Implementation Method 2

An image processing system may calculate pixel luminance values for a display frame or any other metric that can estimate cathode impedance

Methodology Applied

Scientific EffectLuminance calculation: Image Processing

Implementation Method 3

image data presented by the display may cause image data-dependent changes in an impedance used when generating a touch sensing signal

Methodology Applied

Scientific EffectImpedance-based crosstalk: Electrical Resistance

Data Source

PatentUS12293043B2Time-synchronized pixel array and touch array crosstalk mitigation systems and methods

Publication Date: 2025.05.06 APPLE INC

AI summary

Systems, methods, and devices are described that may mitigate display pixel and touch crosstalk noise. A touch processing system may compensate touch scan data to reduce the noise based on a luminance value. An image processing system may determine the luminance value based on image data and a display brightness value of an electronic display. Using the compensated touch scan data, the touch processing system may determine a proximity of a capacitive object to at least one touch sense region of the electronic display.