Active Stylus Resonant Circuit Signal Transmission

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Solution Overview

Problem

Existing digitizer systems face challenges in efficiently synchronizing and communicating with styluses, particularly in terms of power management and signal transmission, which affects the accuracy and efficiency of stylus position detection and user input interpretation.

Innovation Solution

An active stylus with a resonant circuit and a power source that alternates between receive and transmit modes, using a controller to decode synchronization signals and modulate transmitted signals for accurate position detection and information encoding, along with a digitizer system that generates a magnetic flux for stylus synchronization and command transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a passive stylus with no internal power source is used, then device complexity is reduced, but signal transmission capability and position detection accuracy are limited

Engineering Contradiction:
Improvestylus structureVSAvoidstylus position detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The stylus is equipped with an internal power source (battery) that enables it to autonomously generate and transmit electromagnetic signals without requiring external power or complex synchronization mechanisms. This self-powered approach allows the stylus to independently control signal transmission timing and duration, improving position detection accuracy while maintaining relatively simple overall system architecture.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The stylus transmits electromagnetic signals periodically at predetermined time intervals determined by its internal controller. This periodic transmission enables the digitizer system to continuously track stylus position and movement, improving detection accuracy and responsiveness while the internal power source manages energy consumption efficiently.

Inventive Principle:
Principle #19Periodic action

2Measurement precision

If an active stylus with internal power source is used, then signal transmission and position detection accuracy are improved, but power consumption increases

Engineering Contradiction:
Improvestylus position detection accuracyVSAvoidstylus power consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The stylus controller manages power consumption by transmitting electromagnetic signals only at predetermined periodic intervals rather than continuously. The internal power source (battery) is sized and managed to provide sufficient energy for these periodic transmissions, balancing power consumption with the need for accurate position detection and signal transmission.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The stylus maintains continuous position tracking capability through periodic signal transmissions, ensuring that the digitizer system continuously receives position information without gaps. The internal power source is designed to sustain this continuous useful action throughout the intended usage period, optimizing the balance between power consumption and detection accuracy.

Inventive Principle:
Principle #20Continuity of useful action

3Reliability

If external excitation is used to energize the stylus, then synchronization is inherently provided, but device complexity and power management flexibility are reduced

Engineering Contradiction:
Improvestylus synchronizationVSAvoiddigitizer system structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Instead of the digitizer system providing external excitation to energize the stylus (traditional approach), this invention inverts the approach by equipping the stylus with an internal power source that autonomously generates electromagnetic signals. The digitizer system then receives and processes these self-generated signals, reversing the traditional energy flow and control relationship.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The stylus independently manages its own power supply and signal generation through its internal battery and controller, eliminating the need for external excitation from the digitizer system. This self-service capability provides the stylus with greater flexibility in controlling signal transmission timing and duration, while the digitizer system focuses on receiving and processing signals, simplifying its power management requirements.

Inventive Principle:
Principle #25Self-service

4Measurement precision

If continuous signal transmission is used, then position detection accuracy is maintained, but power consumption increases

Engineering Contradiction:
Improvestylus position detection accuracyVSAvoidstylus power consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The stylus controller transmits electromagnetic signals at periodic intervals determined by predetermined timing parameters rather than continuously. This periodic transmission maintains sufficient position detection accuracy for normal usage while significantly reducing power consumption compared to continuous transmission. The internal power source is sized to support this periodic operation throughout the intended usage period.

Inventive Principle:
Principle #19Periodic action

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

Enhances the accuracy and efficiency of stylus position detection and user input interpretation by enabling reliable power-assisted signal transmission and decoding, reducing power consumption, and allowing for precise modulation of signals for additional information conveyance.

Implementation Method 1

the resonant circuit is operative to pick-up a synchronization and/or triggering signal emitted by a digitizer system while in receive mode

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

generating electrical field; and a controller for operating the resonant circuit in a receive mode for receiving the first signal, for decoding the received first signal and for switching operation of the resonant circuit to a transmit mode for generating the electrical field

Methodology Applied
Scientific EffectElectromagnetic oscillation:

Implementation Method 3

a digitizer system that generates a magnetic flux for stylus synchronization and command transmission

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2959365B1Stylus for a digitizer system
Publication Date: 2019.12.25 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP2959365B1 patent drawingFigure 1
  • EP2959365B1 patent drawingFigure 2
  • EP2959365B1 patent drawingFigure 3~4

AI summary

A signal emitting stylus for operation with a digitizer system includes a resonant circuit including a first capacitor and an inductor, the circuit operative to alternate between receiving a wirelessly transmitted first signal and generating electrical field; a controller and a power source. The controller operates the resonant circuit in a receive mode for receiving the first signal, decodes the received first signal and switches operation of the resonant circuit to a transmit mode for generating the electrical field and coupling the electrical field to a digitizer system in response to detecting the first signal. The power source powers generation of the electrical field.