Stylus Pressure Signal Transmission via Orthogonal PN Codes
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Solution Overview
Problem
Current touch panel systems lack an effective method for an active stylus to transmit pressure information precisely, leading to inefficiencies in detecting pressure levels and controlling traces on touch-sensitive screens.
Innovation Solution
A stylus design incorporating a first component with variable impedance and a second component with fixed impedance, both encoded with pseudo-random number (PN) codes, allows for the transmission of electrical signals that accurately represent pressure levels by mixing and transmitting these signals through a conductive tip section, ensuring orthogonal PN codes for synchronization and conflict prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single component transmits electrical signals, then the device structure is simple, but the pressure information transmission precision is insufficient
Solution Approach 1:
The transmission system is divided into two independent components: a first component with variable impedance that changes with pressure, and a second component with fixed impedance. Each component transmits signals independently through the conductive tip section, allowing the system to encode pressure information more precisely by comparing the relative changes in electrical characteristics between the two components.
Solution Approach 2:
The first component's impedance is designed to vary with applied pressure, creating a direct correlation between physical pressure and electrical parameter changes. By measuring how the impedance of the first component changes relative to the stable second component, the system can precisely determine pressure levels while maintaining a relatively simple overall structure.
2Loss of information
If multiple signals are transmitted simultaneously through the same channel, then the information transmission capacity increases, but signal interference and conflict occur
Solution Approach 1:
The system employs spread spectrum modulation where each component's signal is modulated with a unique pseudo-random code sequence. These periodic-like modulated signals are transmitted simultaneously through the same conductive tip section, but the orthogonal codes allow the receiver to separate and decode each signal independently, preventing interference while maintaining high information transmission capacity.
Solution Approach 2:
The conductive tip section acts as an intermediary that combines the electrical signals from both the first and second components. By using orthogonal pseudo-random code modulation, the tip section can transmit multiple signals through the same physical medium without significant interference, as the orthogonal codes enable the receiving end to distinguish and separate the individual signals.
3Measurement precision
If pressure detection accuracy is improved, then the user control precision increases, but the system complexity increases
Solution Approach 1:
The first component's impedance naturally varies with applied pressure, providing self-sensing capability without requiring additional pressure sensors or complex measurement circuits. The component itself serves as both the electrical connector and the pressure-sensing element, eliminating the need for separate sensing mechanisms and reducing overall system complexity while maintaining high pressure detection accuracy.
Solution Approach 2:
The conductive tip section serves multiple functions simultaneously: it acts as the electrical connection medium for signal transmission, the pressure-sensing element through its variable impedance characteristics, and the interface for both components. This multi-functionality reduces the need for additional dedicated components, keeping the system relatively simple while achieving precise pressure detection.
Data Source
AI summary
The present invention provides a stylus for transmitting electrical signals carrying pressure information, comprising: a first component with variable impedance reflecting a pressure, wherein the first component is configured for receiving first signals encoded by a first pseudo-random number (PN) code; a second component with fixed impedance, wherein the second component is configured for receiving second signals encoded by a second PN code; and a conductive tip section configured for: receiving, simultaneously, the first signals from the first component and the second signals from the second component; and transmitting electrical signals which is composed of the first signals and the second signals, wherein the first PN code is orthogonal to the second PN code.