Stylus Signal Detection via Synchronous Demodulation

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Solution Overview

Problem

Conventional styli lack precision and control due to asynchronous interaction with touch sensitive devices, leading to demodulation challenges.

Innovation Solution

A stylus signal detection technique that synchronizes the detected stylus signal with a windowing function for efficient demodulation, using detectors to estimate the start and end times of the stylus signal to facilitate effective demodulation on a touch input device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If conventional styli with bulky tips are used to interact with touch sensitive devices, then the stylus can be simple in structure, but the precision and control of the stylus deteriorates

Engineering Contradiction:

Improvestylus structureVSAvoidstylus precision and control

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system performs preliminary detection of stylus signals by monitoring sense lines for characteristic signal patterns before full demodulation processing. This allows the system to identify stylus presence and prepare appropriate processing windows in advance, improving precision without requiring complex stylus hardware

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The demodulation system dynamically adjusts its processing based on detected signal characteristics. The system switches between different demodulation modes and adapts windowing functions based on real-time signal analysis, enabling precise stylus control through software-based adaptability rather than hardware complexity

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If asynchronous interaction between stylus and touch device is used, then the device operation remains simple, but demodulation challenges increase

Engineering Contradiction:

Improvedevice operationVSAvoiddemodulation difficulty

Core Design Contradiction:

Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The system implements feedback mechanisms where detected stylus signals are analyzed to determine optimal demodulation parameters. The system continuously monitors sense line signals, identifies stylus-specific patterns, and adjusts demodulation windows accordingly, resolving asynchronous interaction challenges through adaptive feedback processing

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary signal analysis and window generation based on detected stylus signals before full demodulation. By pre-processing signals to identify characteristic patterns and prepare appropriate demodulation windows in advance, the system simplifies the overall demodulation process while maintaining ease of operation

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10459546B2Channel aggregation for optimal stylus detection

Publication Date: 2019.10.29 APPLE INC

AI summary

A touch input device configured to detect stylus signals generated by an external stylus is provided. The touch input device includes a plurality of stylus signal detectors that receive at its input a combination of stylus receive channels that are combined in a manner to minimize noise while at the same time keeping the stylus signal strength uniform independent of the position of the stylus on the device.