Fe-based Amorphous Alloy Shielding Sheet for Digitizer Sensitivity
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Solution Overview
Problem
Conventional magnetic field shielding sheets for digitizers in portable terminal devices face issues with low digitizer sensitivity due to low magnetic permeability, geomagnetic sensor distortions caused by high permeability, and high material costs, particularly with the thickness of shielding sheets affecting device thinness and functionality.
Innovation Solution
A magnetic field shielding sheet comprising a heat-treated Fe-based amorphous alloy ribbon sheet, flake-treated into fine pieces with a protective film and double-sided tape, achieving optimal permeability to minimize geomagnetic sensor interference and enhance digitizer sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic field shielding sheet with high magnetic permeability is used to improve digitizer sensitivity, then the shielding effect is enhanced, but geomagnetic sensor distortion occurs
Solution Approach 1:
The patent applies parameter changes by precisely controlling the magnetic permeability of the shielding sheet to fall within the range of 100-500. This specific parameter range optimizes the balance between achieving sufficient magnetic field shielding for digitizer sensitivity while minimizing distortion effects on the geomagnetic sensor, thereby resolving the technical contradiction between shielding effectiveness and sensor interference.
2Reliability
If the thickness of the magnetic field shielding sheet is increased to improve shielding performance, then the magnetic field blocking capability is enhanced, but the device thickness increases
Solution Approach 1:
The patent resolves this contradiction by changing the material parameter (magnetic permeability) rather than the geometric parameter (thickness). By selecting a shielding sheet with optimized magnetic permeability (100-500), the patent achieves effective magnetic field shielding with a thin sheet thickness of 10-50 μm, thus improving shielding performance without increasing device thickness.
3Object-affected harmful factors
If a magnetic field shielding sheet is inserted between the digitizer panel and main circuit board to shield electromagnetic fields, then the electromagnetic interference is reduced, but the assembly complexity increases
Solution Approach 1:
The patent applies the merging principle by integrating the magnetic field shielding sheet directly into the digitizer panel structure. The shielding sheet is positioned at the rear surface of the digitizer panel, merging the shielding function with the existing digitizer assembly rather than adding it as a separate component between the digitizer and main circuit board, thus reducing assembly complexity while maintaining electromagnetic interference shielding.
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 solution effectively blocks magnetic hysteresis distortion, increases permeability uniformity, and improves digitizer sensitivity while maintaining low manufacturing costs and device thinness, addressing the limitations of existing shielding technologies.
Implementation Method 1
heat treating an amorphous ribbon sheet made of the Fe-based amorphous alloy below the crystallization temperature of the alloy and in a temperature range of 445 °C to 460 °C
Data Source
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AI summary
Provided are a magnetic field shielding sheet for a digitizer, which shields an effect of a magnetic field generated from various components of a main body of the portable terminal device and at the same time improves the sensitivity of a digitizer function when the digitizer function is implemented in the portable terminal device, while minimizing an influence upon a geomagnetic sensor, a method of manufacturing the magnetic field shielding sheet, and a portable terminal device using the magnetic field shielding sheet. The magnetic field shielding sheet includes: at least one layer thin magnetic sheet made of a Fe-based amorphous alloy and flake-treated so as to be separated into a plurality of fine pieces; a protective film that is adhered on one surface of the thin magnetic sheet via a first adhesive layer provided on one side of the protective film; and a double-sided tape that is adhered on the other surface of the thin magnetic sheet via a second adhesive layer provided on one side of the double-sided adhesive tape, wherein the thin magnetic sheet is obtained by heat treating an amorphous ribbon sheet made of the Fe-based amorphous alloy at a temperature of 300°C to 480°C.