Stylus Sensor Control for Hover Detection and Sector Scanning
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Solution Overview
Problem
Conventional sensor controllers struggle to detect the burst signal when a stylus is in a hover state due to insufficient signal-to-noise ratio, and may fail to detect the stylus during data signal transmission, 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, sending a predetermined waveform for a longer period if the stylus is undetected, and using a full-range and sector scanning method to detect the stylus position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor controller increases the period of a detecting operation per electrode to improve signal-to-noise ratio, then detection reliability improves, but the ability to detect the burst signal over a wide range deteriorates
Solution Approach 1:
The sensor controller performs detecting operations at multiple different periods. When the stylus is not detected, a longer period is used to improve signal-to-noise ratio. When the stylus is detected, a shorter period is used to scan a wider range. This periodic variation in detection period allows the system to adapt to different operational states and resolve the contradiction between detection reliability and detection range.
2Area of stationary object
If the sensor controller uses all electrodes to scan the wide range, then detection coverage improves, but the time to complete scanning increases
Solution Approach 1:
The sensor controller dynamically adjusts the scanning strategy based on detection results. When the stylus is not detected, all electrodes are used to scan the wide range. When the stylus is detected, the controller switches to using only some electrodes positioned in the vicinity of the detected electrode, thereby reducing scanning time while maintaining detection coverage.
3Productivity
If the stylus sends data signal instead of burst signal, then data transmission efficiency improves, but the sensor controller's ability to detect stylus position deteriorates
Solution Approach 1:
The stylus alternates between sending burst signals and data signals in a periodic manner. By periodically transmitting burst signals with predetermined waveforms, the stylus ensures that the sensor controller can detect its position. During other periods, the stylus sends data signals for efficient data transmission. This periodic alternation resolves the contradiction between data transmission efficiency and detection reliability.
Data Source
AI summary
A sensor controller is connected to an electrode matrix, and is structured to carry out: a finger touch detecting step of detecting a finger touch area based on a signal detected in the electrode matrix; a full-range scanning step of detecting a stylus by scanning a first plurality of electrodes of the electrode matrix; a sector scanning step of deriving a position of the detected stylus by scanning a second plurality of electrodes of the electrode matrix, wherein the second plurality of electrodes is less than the first plurality of electrodes; a determining step of determining whether the position derived in the sector scanning step is included in the finger touch area detected in the finger touch detecting step; and an invalidating step of invalidating the position that is derived in the sector scanning step and is determined to be included in the finger touch area in the determining step.