Auxiliary Loop Coil Reduces Magnetic Flux Leakage in Position Detecting Device
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Solution Overview
Problem
The existing position detecting devices of electromagnetic induction systems suffer from significant leakage of magnetic flux, particularly at the peripheral parts of the sensor unit, which interferes with the transmission and reception of signals to and from the position indicator, leading to reduced operational efficiency.
Innovation Solution
The introduction of an auxiliary loop coil at the corner of the sensor unit allows for the peripheral loop coils to be used only for signal reception, reducing magnetic flux leakage by minimizing their involvement in transmission, and utilizing auxiliary coils to generate a magnetic field in areas where peripheral coils would cause unnecessary radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If transmission current is made to flow through the loop coil at the peripheral part of the sensor unit, then the magnetic field coverage is improved, but the amount of leakage of magnetic flux to the external increases
Solution Approach 1:
The patent divides the sensor unit into two distinct types of loop coils: peripheral loop coils and inner loop coils. The peripheral loop coils are configured to generate magnetic fields primarily in their local peripheral regions, while the inner loop coils handle the central area coverage. This segmentation allows each coil type to be optimized for its specific function, with peripheral coils generating sufficient magnetic flux for edge detection without requiring excessive current that would cause widespread leakage.
Solution Approach 2:
The patent applies different operational characteristics to different parts of the sensor unit. Peripheral loop coils are designed with specific electrical characteristics (such as lower current or different frequency) compared to inner loop coils, creating local quality differences. This allows the peripheral coils to generate adequate magnetic fields for their local detection zones while minimizing the propagation of magnetic flux leakage to external areas.
2Power
If a large current is made to flow through the loop coil at the peripheral part, then the transmission signal strength is improved, but the leakage of magnetic flux increases
Solution Approach 1:
The patent segments the current distribution across the sensor unit by applying different current levels to peripheral versus inner loop coils. The peripheral loop coils operate at optimized current levels sufficient for their local detection needs, while inner loop coils handle the bulk of the signal generation. This prevents the excessive current in peripheral coils that would otherwise generate harmful magnetic flux leakage.
Solution Approach 2:
The patent introduces an intermediate control mechanism through the controller that manages the excitation signals sent to different loop coils. The controller acts as an intermediary that can selectively activate and modulate the current in peripheral loop coils, ensuring they contribute to signal strength without exceeding the threshold that would cause significant magnetic flux leakage.
3Device complexity
If the peripheral loop coils are used for both transmission and reception, then the device complexity is reduced, but the magnetic flux leakage interferes with transmission and reception
Solution Approach 1:
The patent segments the functional roles of loop coils into transmission-dedicated peripheral coils and reception-optimized inner coils. This functional segmentation reduces interference between transmission and reception operations, as the peripheral coils generating strong magnetic fields for transmission do not simultaneously attempt to detect weak return signals, thereby improving overall system reliability.
Solution Approach 2:
The patent implements periodic switching between transmission and reception modes for different loop coils. During transmission phases, peripheral loop coils are activated to generate magnetic fields; during reception phases, they are deactivated or switched to reception mode while inner loop coils handle detection. This time-division multiplexing reduces mutual interference and improves signal reliability.
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
This configuration effectively reduces magnetic flux leakage, enhancing the operational efficiency of the position detecting device by minimizing interference and maintaining signal integrity.
Implementation Method 1
a signal transmitter configured to transmit a signal to one of the first loop coil, the second loop coil, and the auxiliary loop coil in order to generate a magnetic field to induce an induced current in a coil of the position indicator
Implementation Method 2
When the position indicator is close to the loop coil generating the magnetic field, the resonant circuit of the position indicator resonates due to electromagnetic induction to generate an induced magnetic field
Data Source
AI summary
A position detecting device is provided, which is configured to minimize leakage of magnetic flux in an electromagnetic induction system. The position detecting device includes: a sensor unit including a plurality of first loop coils arranged in a first direction and a plurality of second loop coils arranged in a second direction intersecting with the first direction; a yoke sheet provided on a side of the sensor unit that is opposite to a side that faces a position indicator; an auxiliary loop coil provided at a corner part of the sensor unit; a signal transmitter configured to transmit a signal to one of the coils in order to generate a magnetic field to induce an induced current in a coil of the position indicator; and a controller configured to select one of the coils, and to control whether to transmit a signal from the signal transmitter to the selected one of the coils or to make the selected one of the coils receive a signal from the position indicator.