EMR Pen Position Sensing with Switchable Coil Connection Modes
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Solution Overview
Problem
Existing electromagnetic resonance (EMR) methods for detecting the position of a pen within a tablet-type device face suffer from low signal-to-noise ratios without increasing the circuit scale of the sensor controller, and frequent position detection is compromised by elongating the pen signal transmission period.
Innovation Solution
A method involving alternating magnetic fields sent from multiple sending coil conductors in parallel connection modes, with simultaneous detection using detection coils, allowing separation of signals for improved signal-to-noise ratio without increasing circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the transmission period of the pen signal is elongated to improve signal-to-noise ratio, then the signal-to-noise ratio is improved, but the position detection frequency is reduced
Solution Approach 1:
The patent segments the sending coil conductors into multiple groups that can be independently controlled. By dividing the coil array into multiple segments with different connection modes (series/parallel combinations), the system can simultaneously transmit multiple alternating magnetic fields with different frequencies or phases, enabling parallel signal reception that improves detection frequency while maintaining signal-to-noise ratio
Solution Approach 2:
The patent employs periodic switching between different connection modes of the sending coil conductors. By alternating between series and parallel connections in a periodic manner, the system creates time-multiplexed transmission patterns that allow for both extended transmission periods (for high signal-to-noise ratio) and frequent detection cycles (for high detection frequency)
2Measurement precision
If multiple receiving circuits are used to parallelly receive the pen signal for improving signal-to-noise ratio, then the signal-to-noise ratio is improved, but the circuit scale of the sensor controller increases
Solution Approach 1:
The patent merges multiple sending coil conductors into different connection modes (series and parallel combinations) that can be switched dynamically. By combining multiple coils into fewer effective transmission channels with variable impedance, the system achieves parallel reception capabilities without requiring a proportional increase in receiving circuits, thus improving signal-to-noise ratio while controlling circuit scale
Solution Approach 2:
The patent introduces dynamic switching between different connection modes of the sending coil conductors. By making the connection configuration changeable rather than fixed, the system can adapt the same physical hardware to perform multiple reception functions, reducing the need for additional dedicated receiving circuits while maintaining parallel reception capabilities
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
Enhances signal-to-noise ratio without reducing position detection frequency or increasing the sensor controller's circuit scale by utilizing multiple connection modes for alternating magnetic field detection.
Implementation Method 1
An alternating magnetic field is sequentially transmitted from the plurality of Tx coils, and a reflection signal transmitted from the electromagnetic resonance pen is received by the sensor controller via the corresponding Rx coil
Implementation Method 2
The EMR sensor includes a plurality of Tx coils arranged side by side in a y direction and a plurality of Rx coils arranged side by side in an x direction. An alternating magnetic field is sequentially transmitted from the plurality of Tx coils
Data Source
AI summary
Provided is a position detection method including connecting each of a plurality of sending coil conductors provided in parallel to a driving circuit in a first connection mode, and detecting, by using detection coils, an alternating magnetic field generated by an indicator according to alternating magnetic fields simultaneously sent from the plurality of sending coil conductors in response to alternating current supplied from the driving circuit, to obtain a first result, connecting each of the plurality of sending coil conductors to the driving circuit in a second connection mode, and detecting, by using the detection coils, an alternating magnetic field generated by the indicator according to alternating magnetic fields simultaneously sent from the plurality of sending coil conductors in response to alternating current supplied from the driving circuit, to obtain a second result; and deriving a position of the indicator based on the first and second results.