Non-uniform Constellations for Stylus Data Transmission
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Solution Overview
Problem
Existing touch-sensitive computing devices face limitations in achieving high frame rates while encoding sufficient data due to constraints on modulation schemes when using one-dimensional correlators, which restrict the amount of information that can be transmitted between an active stylus and a digitizer.
Innovation Solution
A signal modulation scheme that maps correlation magnitudes from one-dimensional correlators to a non-uniform constellation of demodulation symbols, allowing multiple data bits to be encoded in each symbol, thereby increasing data rates and enabling high frame rates without requiring multi-dimensional correlators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one-dimensional correlators are used for electrostatic communication, then device complexity is reduced, but data transmission rate is limited
Solution Approach 1:
The patent changes the parameter of constellation structure from traditional uniform to non-uniform, allowing different symbol spacing to encode multiple bits per correlation magnitude. This enables the one-dimensional correlator to achieve higher data transmission rates by mapping correlation outputs to a non-uniform constellation where each symbol represents multiple data bits, resolving the contradiction between simple correlator design and limited data rate
Solution Approach 2:
The patent introduces a new dimension of information encoding by using the magnitude value itself (not just phase) in a non-uniform constellation. This transforms the one-dimensional correlator output into a multi-bit encoding system, effectively adding information capacity without increasing correlator dimensionality, thus maintaining low device complexity while improving productivity
2Ease of manufacture
If one-dimensional correlators are used, then ease of manufacture is improved, but information encoding capacity deteriorates
Solution Approach 1:
By changing the constellation from uniform to non-uniform spacing, the patent enables each correlation magnitude to represent multiple data bits. The non-uniform constellation design allows efficient packing of information where symbols are strategically positioned to maximize data capacity, thereby improving encoding capacity without complicating the one-dimensional correlator implementation
Solution Approach 2:
The patent employs dynamic modulation schemes where the stylus can vary multiple waveform characteristics (amplitude, phase, frequency) to map onto the non-uniform constellation. This dynamic approach allows flexible information encoding that maximizes data capacity while keeping the correlator structure simple and manufacturable
3Measurement precision
If high frame rates are achieved, then position determination accuracy is improved, but data transmission capacity is reduced
Solution Approach 1:
The non-uniform constellation enables multiple data bits to be encoded in each symbol period, allowing high frame rates to be maintained while increasing overall data transmission capacity. The improved encoding efficiency means that even at high speeds, sufficient data capacity is preserved, resolving the trade-off between frame rate and data capacity
Solution Approach 2:
The patent enables continuous high-rate data transmission by efficiently packing multiple bits per symbol in the non-uniform constellation. This continuous efficient encoding maintains high frame rates for accurate position determination while simultaneously preserving data transmission capacity through optimized information density
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 approach enhances data transmission rates and supports high frame rates, ensuring accurate position determination and additional data communication between the stylus and digitizer, while being compatible with devices using one-dimensional correlators.
Implementation Method 1
a stylus electrode of an active stylus capacitively coupled to one or more electrodes of a touch sensor of the touch-sensitive device
Data Source
AI summary
A touch-sensitive device includes a touch sensor including a plurality of electrodes and receive circuitry configured to interpret a response on one or more electrodes of the plurality of electrodes based on stylus waveforms being driven on a stylus electrode of an active stylus. The touch-sensitive device is configured to correlate the stylus waveforms with one or more reference waveforms to produce correlation magnitudes; The touch-sensitive device is further configured to map each correlation magnitude to a demodulation symbol selected from a plurality of demodulation symbols of a one-dimensional, non-uniform constellation. Each demodulation symbol encodes multiple data bits. The touch-sensitive device is further configured to decode the mapped demodulation symbols to determine a plurality of data bits of stylus information of the active stylus.