EMR Pen Resonance Switching for Multilevel Phase Signals
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Solution Overview
Problem
Conventional electromagnetic induction systems are limited to transmitting a single bit of information, preventing the achievement of multilevel pen signals like those used in QPSK or 16QAM in mobile communications.
Innovation Solution
An electromagnetic induction pen with a resonance circuit that temporarily changes its resonance frequency from a first frequency to a second frequency based on the information to be transmitted, and then returns to the first frequency, allowing for phase-modulated pen signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the resonance frequency of the resonance circuit is changed to transmit multilevel information, then the information transmission capacity is improved, but the reception level decreases due to frequency shift from the predetermined frequency
Solution Approach 1:
The resonance frequency is changed periodically in a specific sequence corresponding to multilevel information (e.g., 0°→90°→180°→270° phase shifts for 2-bit information), allowing multiple bits to be transmitted in one communication cycle. This periodic frequency modulation enables multilevel transmission while the position detecting device can track and demodulate the signal properly.
Solution Approach 2:
The position detecting device performs quadrature detection to measure both the in-phase and quadrature components of the received signal, providing feedback information about the signal's phase and amplitude. This allows the system to accurately demodulate the frequency-changed signal and recover the transmitted multilevel information even when the resonance frequency shifts.
2Loss of information
If the resonance frequency is greatly changed from the predetermined frequency, then more information can be transmitted, but the reception level in quadrature detection decreases
Solution Approach 1:
The resonance frequency is changed to specific discrete values (first frequency, second frequency, third frequency, fourth frequency) that correspond to different phase shifts (0°, 90°, 180°, 270°). These frequency changes are carefully selected to represent multilevel information while remaining within the detectable range of the quadrature detection system, balancing information capacity with reception quality.
3Device complexity
If conventional EMR system is used, then the system structure is simple, but only one bit information can be transmitted at a time
Solution Approach 1:
The resonance circuit undergoes periodic frequency changes during one communication cycle, with each frequency state representing a specific phase shift. This periodic modulation allows multiple bits of information to be encoded and transmitted simultaneously, increasing information capacity while maintaining the basic EMR system structure.
Solution Approach 2:
The resonance frequency is made dynamic by introducing controlled frequency shifts based on the information to be transmitted. Instead of a fixed resonance frequency, the system dynamically adjusts the frequency to encode multilevel information, transforming a static parameter into a dynamic signaling mechanism without requiring complex additional hardware.
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
Enables the achievement of multilevel pen signals without decreasing the reception level in quadrature detection, effectively overcoming the limitations of conventional systems.
Implementation Method 1
The position detecting device has a function of sending out an alternating magnetic field from the panel surface by passing an alternating current through one or more loop coils. When the coil within the electromagnetic induction pen enters the alternating magnetic field, electromagnetic induction induces an electromotive force in the coil.
Implementation Method 2
an electromagnetic induction pen including a resonance circuit that, in operation, transmits a pen signal by using power obtained from an alternating magnetic field sent out by a position detecting device, and a control circuit that, in operation, causes the resonance circuit to transmit the pen signal phase-modulated according to information to be transmitted to the position detecting device, by temporarily changing a resonance frequency of the resonance circuit from a first frequency to a second frequency different from the first frequency based on the information and then returning the resonance frequency of the resonance circuit to the first frequency
Data Source
AI summary
An electromagnetic induction pen of an electromagnetic induction system (EMR) system that can achieve a multilevel pen signal. The electromagnetic induction pen includes a resonance circuit that transmits a pen signal by using power obtained from an alternating magnetic field sent out by a position detecting device, and a control circuit that causes the resonance circuit to transmit the pen signal phase-modulated according to information to be transmitted to the position detecting device, by temporarily changing a resonance frequency of the resonance circuit from a first frequency to a second frequency different from the first frequency based on the information and then returning the resonance frequency of the resonance circuit 23 to the first frequency.