Position Detector Frequency Feedback for Pen Signal Accuracy
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Solution Overview
Problem
Conventional position detection systems experience attenuation of the pen signal amplitude due to pen pressure, leading to reduced signal-to-noise ratio and decreased position detection accuracy.
Innovation Solution
A position detector and integrated circuit that includes a coil functioning as a sensor and a signal processing circuit to generate and transfer a frequency-based alternating magnetic field, detecting and generating a transfer signal that adapts to the frequency of the pen signal, thereby maintaining resonance energy and signal amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single frequency transfer signal is used for position detection, then the device complexity is reduced and ease of operation is improved, but the signal amplitude is attenuated when pen pressure is applied, reducing measurement precision
Solution Approach 1:
The transfer signal frequency is made dynamic rather than fixed. The signal processing circuit continuously adjusts the transfer signal frequency to track the resonance frequency of the position indicator, which changes with pen pressure. This dynamic adaptation maintains signal amplitude and detection accuracy without requiring complex additional hardware
Solution Approach 2:
A feedback mechanism is implemented where the detected pen signal frequency is used to adjust the transfer signal frequency. The signal processing circuit detects the frequency of the pen signal and uses this information to generate a new transfer signal with updated frequency, creating a closed-loop system that maintains optimal resonance conditions
2Measurement precision
If the transfer signal frequency is continuously adjusted to track pen signal frequency, then signal amplitude attenuation is suppressed and measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The frequency adjustment operates periodically rather than continuously. The signal processing circuit generates transfer signals in periodic TX periods and performs frequency detection in RX periods, cycling between signal transmission and frequency analysis. This periodic operation maintains detection accuracy while significantly reducing average power consumption compared to continuous frequency tracking
Solution Approach 2:
The system performs preliminary frequency detection before generating the next transfer signal. By detecting the current pen signal frequency and using it to pre-adjust the next transfer signal frequency, the system maintains resonance conditions in advance, ensuring optimal signal amplitude from the start of each TX period
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
The proposed solution suppresses the attenuation of the pen signal amplitude, maintaining resonance energy and signal quality, thus enhancing position detection accuracy and reducing power consumption.
Implementation Method 1
a coil (104) functioning as a sensor and including a transfer coil (104) that transfers an alternating magnetic field based on a transfer signal to a position indicator (2)
Implementation Method 2
The electric circuit for detecting the pen pressure in the position indicator includes a resonant circuit including a position indication coil and a resonant capacitor
Data Source
AI summary
Provided is a position detector including a coil configured to function as a sensor and including a transfer coil that transfers an alternating magnetic field based on a transfer signal to a position indicator, and a signal processing circuit connected to the coil and configured to detect a pen signal generated by the position indicator, generate the transfer signal with a frequency based on frequency information of the detected pen signal, and transfer the transfer signal to the transfer coil.