Active Stylus RF Signal Generation for Touch Precision
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Solution Overview
Problem
Conventional passive styluses for capacitive touch systems have limitations, including the need for large tips to disrupt electric field lines, difficulty in precise location detection, and inability to distinguish stylus touches from finger or other object touches, leading to inaccurate sensing and filtering issues.
Innovation Solution
Active styluses that can act as either a drive or sense electrode, capable of creating an electric field or sensing capacitively coupled signals, allowing for improved stylus sensing on mutual capacitive touch sensor panels without significant additional cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional passive stylus is used with a large tip to disrupt electric field lines, then the stylus can be detected by the capacitive touch sensor panel, but the touch location precision deteriorates and the tip size cannot be reduced
Solution Approach 1:
The patent transforms the stylus from a passive object to an active one by changing its electrical parameters - it now generates its own RF signal and can be actively sensed by the touch panel, allowing the tip to be made smaller while maintaining detection precision
Solution Approach 2:
The patent replaces the passive mechanical disruption of electric field lines with an active electromagnetic signal generation approach, where the stylus transmits RF signals that are detected by the touch panel's sense electrodes
2Device complexity
If a conventional passive stylus is used, then the structure remains simple, but the ability to distinguish stylus touches from finger or other object touches deteriorates
Solution Approach 1:
The patent changes the electrical parameters of the stylus by equipping it with an RF signal generator, allowing the touch panel to distinguish stylus touches from finger touches through signal detection and analysis
Solution Approach 2:
The patent implements a feedback mechanism where the stylus generates RF signals and the touch panel detects and processes these signals to identify and differentiate stylus touches from other touch types
3Measurement precision
If an active stylus with RF signal generation is implemented, then stylus sensing precision and distinguishability are improved, but the device complexity and cost increase
Solution Approach 1:
The patent makes the touch panel's sense electrodes multi-functional by enabling them to detect both traditional capacitive touches and active RF signals from the stylus, reducing the need for separate dedicated components
Solution Approach 2:
The patent uses the existing RF signal as an intermediary carrier to transmit touch information from the stylus to the touch panel, leveraging existing electromagnetic wave technology rather than requiring entirely new communication protocols
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 active styluses enable more precise and distinguishable stylus sensing, allowing for smaller tips and better touch area differentiation, reducing inaccuracies and enhancing touch location determination.
Implementation Method 1
the styluses disclosed in the various embodiments of this disclosure can either act as a drive electrode to create an electric field between the drive electrode and the sense lines of a mutual capacitive touch sensor panel
Implementation Method 2
or as a sense electrode for sensing capacitively coupled signals from one or more stimulated drive rows and columns of the touch sensor panel
Data Source
AI summary
An active stylus is disclosed. The stylus includes an electrode at a tip of the stylus; and powered circuitry coupled to the electrode and configured for capacitively coupling the electrode with a capacitive touch sensor panel. The powered circuitry can further include drive circuitry configured to output a drive voltage at the electrode and/or sense circuitry configured to sense a voltage received at the electrode.