Stylus Signal Duty-Cycle Modulation With Reference Timing
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Solution Overview
Problem
Existing stylus technologies face challenges in accurately transmitting signal values to touch sensitive processing apparatuses due to variations in touch electrode density and hover distances, leading to errors in signal strength and duty cycle ratios.
Innovation Solution
The implementation of a transmitter that modulates electrical signals with a first duty cycle in a reference signal time period and a second duty cycle in a modulation signal time period, where the ratio of the second duty cycle to the first duty cycle corresponds to the signal value, and the lengths and amplitudes of both periods are kept constant, allowing for accurate signal value transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a stylus transmits electric signals via an electrode to a touch panel, then signal transmission is achieved, but variations in touch electrode density and hover distances cause errors in signal strength and duty cycle ratios
Solution Approach 1:
The signal transmission is divided into two separate time periods: a reference signal time period for transmitting reference electric signals and a modulation signal time period for transmitting modulation electric signals. This segmentation allows independent measurement and comparison of signal characteristics, eliminating errors caused by varying electrode density and hover distances by using the reference period as a baseline for correction.
Solution Approach 2:
The transmitter alternates between reference signal transmission and modulation signal transmission in periodic time periods. The controller switches the signal modulator between these two modes, allowing the receiver to periodically compare modulation signals against reference signals, thereby compensating for environmental variations and improving measurement precision.
2Loss of information
If electrical signals are modulated with different duty cycles to carry signal values, then information transmission capability is improved, but errors arise due to variations in touch electrode density and hover distances
Solution Approach 1:
The reference electric signals transmitted in the reference signal time period serve as a feedback baseline for the modulation electric signals. The receiver measures the duty cycle ratio between modulation signals and reference signals, using the reference signals to compensate for variations caused by electrode density and hover distance, thereby maintaining accurate signal value transmission despite duty cycle modulation.
3Measurement precision
If the lengths and amplitudes of reference and modulation signal periods are kept constant, then measurement consistency is improved, but device complexity increases due to precise timing control requirements
Solution Approach 1:
The controller pre-configures the signal modulator with fixed time period lengths and amplitude levels for both reference and modulation signal transmissions. By establishing these parameters in advance, the system ensures consistent measurement conditions without requiring complex real-time adjustments, simplifying the control mechanism while maintaining measurement precision.
Data Source
AI summary
A transmitter comprising: a signal modulator for transmitting electrical signals via an electrode, wherein the electrical signals carry a message representing a signal value; and a controller, coupled to the signal modulator, configured for having the signal modulator transmitting the electrical signals with a first duty cycle in a reference signal time period and transmitting the electrical signals with a second duty cycle in a modulation signal time period, wherein a first ratio corresponding to the second duty cycle and the first duty cycle is corresponding to the signal value, wherein the lengths of the reference signal time period and the modulation signal time period are the same, and wherein the maximum amplitudes of the electrical signals during the reference signal time period and the modulation signal time period are the same.