Stylus Signal Noise Correction via Differential Electrode Sensing
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Solution Overview
Problem
Touch sensitive devices struggle to precisely detect stylus presence and position due to noise interference from electrical components, leading to degraded precision and control.
Innovation Solution
A differential sensing technique that estimates and subtracts noise from stylus signals by measuring signals from electrodes a pre-determined distance away, minimizing noise interference and enhancing signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a stylus transmits stimulation signals to a touch sensitive device, then precision and control are improved, but noise from electrical components degrades the signal quality
Solution Approach 1:
The patent introduces intermediary reference electrodes positioned at a predetermined distance from the stylus contact point. These reference electrodes act as mediators to capture noise signals separately, allowing the system to distinguish between actual stylus signals and electrical noise. The reference electrodes serve as a buffer zone that isolates the measurement process from direct noise contamination.
Solution Approach 2:
The patent extracts the noise component from the composite signal by measuring it separately through reference electrodes. By taking out the noise measurement process from the main signal detection, the system can isolate and remove noise contributions from the stylus signal processing, leaving only the pure stylus interaction data.
2Ease of manufacture
If conventional styli with bulky tips are used, then ease of manufacture is improved, but precision and control are degraded
Solution Approach 1:
The patent changes the electrical parameters of the stylus by incorporating stimulation signal transmission capability. This transforms the stylus from a passive capacitive object to an active signal source, enabling precise detection of stylus presence, position, and applied force through electrical signal measurements rather than relying solely on physical tip characteristics.
3Measurement precision
If noise estimation is performed using electrodes close to the stylus signal, then noise correction is improved, but stylus signal contamination occurs
Solution Approach 1:
The patent applies local quality by positioning reference electrodes at a specific predetermined distance from the stylus contact point. This spatial differentiation creates zones with different signal characteristics: the measurement electrode captures both stylus signal and noise, while the reference electrode captures primarily noise. The local spatial arrangement enables selective signal capture based on position.
Data Source
AI summary
A touch sensitive device can be capable of detecting signals generated by a stylus and correcting the detected stylus signals for effects due to noise present on the device. In one example, signals are taken from one or more electrodes that are a pre-determined distance away from an electrode in which a stylus signal is detected. The pre-determined distance can be empirically determined such that a noise estimate can be generated such that the electrodes have a higher probability of containing only noise that is highly correlated to the noise present on a detected stylus signal. The generated noise estimate is then subtracted from a detected stylus signal to reduce the effect of noise on the stylus signal.