Magnetic Shielding Sheet for Digitizer Interference
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Solution Overview
Problem
Conventional magnetic field shielding members, such as those using metal ribbons, can interfere with digitizer functions in portable terminal devices due to their magnetic properties, particularly when a magnesium frame is used, leading to reduced digitizer performance and interference with geomagnetic sensors.
Innovation Solution
A magnetic field shielding sheet comprising a main sheet made of an amorphous or nanocrystalline alloy with a shielding layer of flake pieces, a cover layer, and double-sided tape, along with a sub-sheet attached to the edges of the main sheet, is used to shield magnetic fields from the magnesium frame and improve digitizer sensitivity without affecting geomagnetic sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional metal ribbon shielding member is used, then electromagnetic fields are shielded, but the digitizer function is interfered with and geomagnetic sensor performance is degraded
Solution Approach 1:
The patent changes the magnetic permeability parameter of the shielding material by using amorphous or nanocrystalline alloys with specifically controlled permeability values (10-100), which are lower than conventional materials. This parameter change allows the material to shield electromagnetic fields while minimizing interference with digitizer and sensor functions.
Solution Approach 2:
The patent employs composite material structures including amorphous or nanocrystalline alloy ribbons combined with specific adhesive layers and protective coatings. This composite approach optimizes both shielding performance and compatibility with sensitive components by combining materials with complementary properties.
2Strength
If a magnesium frame is used for the portable terminal device, then device strength and lightness are improved, but digitizer sensitivity is reduced due to magnetic field interference
Solution Approach 1:
The patent introduces a magnetic field shielding sheet as an intermediary component between the magnesium frame and the digitizer. This intermediary material blocks magnetic field lines from reaching the digitizer, preventing interference while allowing the magnesium frame to maintain its structural advantages.
Solution Approach 2:
The shielding sheet is strategically positioned only in areas where magnetic field interference occurs between the magnesium frame and digitizer components. This localized approach provides targeted protection without adding unnecessary material or complexity to regions where shielding is not required.
3Object-affected harmful factors
If the magnetic field shielding sheet uses high permeability material, then electromagnetic field shielding is improved, but digitizer sensitivity is negatively affected
Solution Approach 1:
The patent optimizes the magnetic permeability parameter to a specific range (10-100), which is lower than conventional high-permeability materials. This controlled parameter change achieves sufficient electromagnetic field shielding while preventing excessive magnetic field concentration that would interfere with digitizer sensitivity.
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 shielding sheet effectively reduces the permeability of the magnetic field, enhancing digitizer sensitivity and performance while preventing interference from the magnesium frame and shielding electromagnetic fields within portable terminal devices.
Implementation Method 1
a magnetic field shielding sheet comprising: a magnetic field shielding main sheet that is disposed on a rear surface of the digitizer to thus prevent affecting the digitizer; and a magnetic field shielding sub-sheet that is laminated in a dual on at least one of four side edges of the magnetic field shielding main sheet, and to prevent the digitizer from being affected by a magnesium frame
Implementation Method 2
by performing an overheating process at a critical temperature or higher when heat-treating ribbons of a Fe-based amorphous alloy, to thus reduce permeability of the magnetic field shielding sheet into optimum permeability
Implementation Method 3
performing an overheating process at a critical temperature or higher when heat-treating ribbons of a Fe-based amorphous alloy, to thus reduce permeability of the magnetic field shielding sheet into optimum permeability
Data Source
AI summary
A magnetic field shielding sheet includes: a magnetic field shielding main sheet disposed on the back of the digitizer to thus prevent affecting the digitizer; and a magnetic field shielding sub-sheet laminated in a dual on at least one of four side edges of the magnetic field shielding main sheet, and to prevent affecting the digitizer by the magnesium frame inside the portable terminal, wherein the magnetic field shielding main sheet includes a shielding layer made of a plurality of pieces, a cover layer adhered to one surface of the shielding layer, and a double-sided tape adhered to the other surface of the shielding layer. A magnetic field arising from various components incorporated in a portable terminal device is shielded by the magnetic field shielding main sheet while the magnetic field shielding sub-sheet prevents a digitizer from being affected by a magnesium frame, thereby enhancing performance of the digitizer.