Floating Pixel Diffusers for Touch Sensor Wobble Error Reduction

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Capacitive touch sensor panels experience 'wobble error' when a stylus is positioned between electrodes, due to non-linear signal profiles, leading to inaccuracies in position detection.

Innovation Solution

Incorporating diffusing elements made of conductive material that spread the signal from a stylus to multiple electrodes, making the signal profiles more linear and reducing wobble error, while also improving optical uniformity by bridging visible areas between electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional electrode configurations are used in capacitive touch sensor panels, then the device structure remains simple, but wobble error increases and position detection accuracy deteriorates when a stylus is positioned between electrodes

Engineering Contradiction:
Improveposition detection accuracyVSAvoidelectrode structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the electrode structure into multiple segments: sense electrodes, dummy electrodes, and floating conductive segments. This segmentation allows each component to serve a specific function - sense electrodes for signal detection, dummy electrodes for optical uniformity, and floating segments for signal diffusion - thereby improving position detection accuracy while maintaining manageable structural complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces floating conductive segments as intermediary elements between the sense electrodes and the stylus. These floating segments act as mediators that diffuse the capacitive signal from the stylus to multiple sense electrodes, creating a more linear signal profile and reducing wobble error without requiring fundamental changes to the electrode architecture

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If floating conductive segments are added to diffuse signals and improve position accuracy, then measurement precision improves, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improveposition detection accuracyVSAvoidmanufacturing complexity
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent merges the functions of signal diffusion and optical uniformity improvement into a single floating conductive structure. The same floating conductive segments that diffuse signals to reduce wobble error also serve as dummy electrodes to bridge visible areas between electrodes, thereby improving optical uniformity. This merging reduces the total number of components and simplifies the manufacturing process

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The floating conductive segments are designed to perform multiple functions simultaneously: they act as signal diffusion elements to improve position detection accuracy, serve as dummy electrodes to improve optical uniformity, and maintain electrical isolation to prevent signal interference. This multi-functionality reduces the need for separate components and simplifies the overall device structure

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 reduces wobble error and enhances the accuracy of stylus position detection and optical uniformity of the touch sensor panel by diffusing the signal capacitance, resulting in improved performance and user experience.

Implementation Method 1

capacitive touch sensor panels experience 'wobble error' when a stylus is positioned between electrodes

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

floating segments of conductive material can form diffusing elements configured to diffuse signals from a stylus to two or more electrodes

Methodology Applied
Scientific EffectSignal diffusion: Diffusion

Implementation Method 3

diffusing elements can improve the optical uniformity of the touch sensor panel by bridging visible areas between electrodes where no conductive material is formed

Methodology Applied
Scientific EffectOptical uniformity:

Data Source

PatentEP3796141B1Merged floating pixels in a touch screen
Publication Date: 2024.07.24 APPLE INC
  • EP3796141B1 patent drawingFigure 1
  • EP3796141B1 patent drawingFigure 2A~2B
  • EP3796141B1 patent drawingFigure 3A~3B

AI summary

Touch sensor panel configurations for reducing wobble error for a stylus translating on a surface over and between electrodes of the touch sensor panel are disclosed. In some examples, electrodes with more linear signal profiles are correlated with lower wobble error. In some examples, diffusing elements formed of floating segments of conductive materials can diffuse signal from a stylus to a plurality of electrodes, thus, making the signal profiles associated with the electrodes more linear. In addition, diffusing elements can be configured to improve the optical uniformity of the touch sensor panel. In some examples, the diffusing elements can be formed on the same layer as floating dummy pixels and resemble a plurality of merged floating dummy pixels.