Bidirectional Stylus Signaling for Wide-Range Hover Detection
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Solution Overview
Problem
Conventional sensor controllers struggle to detect a stylus in a hover state due to insufficient signal-to-noise ratio, and may fail to detect the stylus when it sends a data signal instead of a burst signal, especially when scanning a wide range.
Innovation Solution
The stylus is designed to bidirectionally communicate with a sensor controller, allowing it to determine the signal duration based on uplink signals and send either a predetermined waveform for a longer period or a data signal depending on the sensor controller's detection status, and the sensor controller performs full-range and sector scanning using electrode matrices to enhance detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor controller increases the period of detecting operation per electrode to improve signal-to-noise ratio for hover state detection, then the S/N ratio is improved, but the burst signal cannot be detected over a wide range of the touch surface
Solution Approach 1:
The sensor controller dynamically adjusts the detecting operation period based on the detected signal quality. When a burst signal with sufficient S/N ratio is detected, the controller extends the detecting operation period for that electrode to improve hover state detection. This dynamic adjustment allows the system to maintain wide detection coverage while improving reliability where needed.
Solution Approach 2:
The sensor controller applies different detecting operation periods to different electrodes based on local signal conditions. Electropdes that detect burst signals with sufficient S/N ratio receive extended detecting periods, while other electrodes maintain standard periods. This localized optimization resolves the contradiction by improving reliability only where signal quality permits, preserving overall detection range.
2Area of stationary object
If the sensor controller scans all electrodes to detect burst signal over wide range, then the detection coverage is improved, but the time required for scanning increases causing missed detections
Solution Approach 1:
The sensor controller performs a preliminary scanning phase using a reduced set of electrodes or reduced scanning frequency to quickly identify potential burst signal locations. Once a candidate electrode is identified, the controller then performs a more thorough detection at that location. This preliminary action reduces overall scanning time while maintaining detection coverage.
Solution Approach 2:
The scanning process is divided into multiple phases: an initial wide-range scan using fewer electrodes to identify potential signal sources, followed by focused detection at identified locations. This segmentation allows the system to maintain wide detection coverage while minimizing the time spent on exhaustive scanning of all electrodes.
3Productivity
If the stylus sends data signal instead of burst signal, then the communication efficiency is improved, but the sensor controller may fail to detect the stylus position
Solution Approach 1:
The stylus periodically transmits burst signals at predetermined intervals during hover movement, even when data signals are being transmitted. This periodic burst signal transmission ensures that the sensor controller can continuously track stylus position while maintaining efficient data communication between transmission intervals.
Solution Approach 2:
The burst signal serves as an intermediary reference signal that enables the sensor controller to maintain awareness of stylus position. While data signals carry efficient communication content, the periodic burst signals act as a mediator that ensures continuous detectability, allowing the system to switch between communication modes without losing tracking capability.
Data Source
AI summary
A stylus capable of bidirectionally communicating with a sensor controller includes a receiver that receives an uplink signal sent by the sensor controller, a controller that determines whether a signal having a predetermined waveform is to be continuously sent over a second time period or to be continuously sent over a first time period longer than the second time period, on the basis of the uplink signal, and a transmitter that continuously sends the signal having the predetermined waveform over the first time period or the second time period on the basis of the result of determination by the controller. As a result, the sensor controller can detect a burst signal from the stylus over a wide range in a sensor touch surface, to thereby reduce the possibility that the sensor controller may fail to detect the burst signal.