Active Stylus Hover Protocol via Segmented Waveform Frames
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Solution Overview
Problem
In touch-sensitive computing devices, the interference between active stylus waveforms and touch sensing operations reduces the accuracy of touch sensing and communication robustness, as the stylus may falsely interpret the digitizer's operating state, leading to incorrect interpretation of touch data.
Innovation Solution
The approach uses the same waveform to communicate the position or hovering state of the stylus at different times based on time synchronization, eliminating the need for the digitizer to indicate its operating state, thereby avoiding interference with touch sensing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stylus transmits waveforms to communicate position and state information, then communication functionality is enabled, but interference with touch sensing operations occurs reducing accuracy
Solution Approach 1:
The communication frame is segmented into distinct sub-frames: locate sub-frames for position communication and report sub-frames for state information. This segmentation allows the system to separate position transmission (which can occur during full-search) from state reporting (which requires local-search mode), thereby preventing interference with touch sensing operations while maintaining communication robustness
Solution Approach 2:
The stylus transmits waveforms periodically according to a structured communication frame that alternates between locate sub-frames and report sub-frames. This periodic transmission pattern synchronized with the digitizer's search modes ensures that position updates occur during full-search periods while state information is communicated during local-search periods, eliminating continuous interference with touch sensing
2Area of stationary object
If the digitizer operates in full-search mode to scan for touches, then touch detection coverage is maximized, but stylus state information communication is lost
Solution Approach 1:
The digitizer alternates between full-search mode (for broad touch detection coverage) and local-search mode (for receiving stylus state information). This periodic switching ensures that both touch detection coverage and stylus state information communication are maintained at different time intervals without compromising either function
Solution Approach 2:
The stylus transmits its state information in report sub-frames that are scheduled in advance within the communication frame structure. The digitizer is preliminarily configured to switch to local-search mode at the expected time of report sub-frames, ensuring that stylus state information is captured before the next full-search cycle begins
3Reliability
If the stylus transmits continuous waveforms to maintain communication, then communication robustness is improved, but energy consumption increases
Solution Approach 1:
Instead of continuous transmission, the stylus transmits waveforms periodically according to the structured communication frame with locate sub-frames and report sub-frames. This periodic transmission maintains communication robustness by ensuring regular position and state updates while significantly reducing energy consumption compared to continuous transmission
Solution Approach 2:
The stylus transmits only the necessary minimum information in each sub-frame (position in locate sub-frames, state in report sub-frames) rather than continuous streams of data. This partial action approach maintains adequate communication robustness while minimizing energy expenditure
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
This method enhances the accuracy of touch sensing and communication between the stylus and digitizer by ensuring that the same waveform does not interfere with touch sensing operations, improving the robustness of communication and reducing errors in stylus-display electrostatic communication.
Implementation Method 1
upon receiving, via electrostatic coupling of one or more electrodes of the plurality of electrodes with a stylus electrode of an active stylus, a first waveform
Data Source
AI summary
An active stylus includes a stylus electrode, receive circuitry, and transmit circuitry. The stylus electrode is configured to capacitively couple with one or more electrodes of a capacitance-based touch sensor of a touch-sensitive device. The receive circuitry is operatively coupled to the stylus electrode and configured to receive a synchronization waveform from the touch-sensitive device. The transmit circuitry is operatively coupled to the stylus electrode and configured to, upon receiving the synchronization waveform, transmit stylus information to the touch-sensitive device according to a communication frame including a first set of sub-frames and a second set of sub-frames. The transmit circuitry is configured to transmit a first waveform during the first set, if the active stylus is hovering, transmit the first waveform during the second set, and if the active stylus is not hovering, transmit one or more additional waveforms during the second set.