Planar Coil Thickness Reduction via Flexible PCB and Thin Magnetic Film
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Solution Overview
Problem
Existing noncontact power-transmission coils for portable terminals, such as mobile phones, face challenges in reducing thickness due to overlapping electric wire portions, which hinders the miniaturization of these devices.
Innovation Solution
A noncontact power-transmission coil design featuring a spirally-wound planar coil mounted on a flexible printed-circuit board with a magnetic sheet covering both the flat and side surfaces, eliminating overlapping wire ends and allowing for a thinner profile by using a multi-layered structure and adhesion or resin mounting methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electric wire end on the inner periphery is passed over (or under) the spirally-wound electric wire portion and drawn to the outside, then the coil can be formed, but the overlapped portion causes large increase in thickness
Solution Approach 1:
The patent transitions from a three-dimensional wire winding approach to a two-dimensional planar pattern approach. The coil is formed by creating a spiral pattern on a flat flexible substrate, eliminating the need to pass wire ends over other wire portions. This dimensional change from 3D wire routing to 2D pattern layout resolves the thickness issue caused by wire overlap.
Solution Approach 2:
The patent replaces the mechanical wire winding and routing system with a printed circuit board (PCB) trace system. Instead of manually or mechanically winding wire and managing its ends, the coil is fabricated as a conductive pattern on the flexible substrate, eliminating the mechanical complexity of wire end management and the associated thickness problems.
2Object-affected harmful factors
If a magnetic sheet is attached on one planar portion of the planar coil, then magnetic field radiation is prevented, but the overall thickness increases
Solution Approach 1:
The patent employs an extremely thin magnetic sheet (1-3 μm) deposited as a film on the flexible substrate, rather than using conventional thick magnetic shielding materials. This thin film approach provides magnetic field radiation prevention while adding minimal thickness to the overall coil structure.
Solution Approach 2:
The patent changes the thickness parameter of the magnetic shielding material from conventional thick sheets to ultra-thin films (1-3 μm). This parameter change maintains the magnetic shielding function while dramatically reducing the thickness contribution to the overall coil assembly.
3Power
If a spirally-wound planar coil is used in a portable terminal, then electromagnetic induction for charging is achieved, but the coil thickness prevents further miniaturization
Solution Approach 1:
The patent uses a planar spiral coil pattern fabricated on a flexible substrate, transforming the coil from a bulky three-dimensional wire assembly into a thin two-dimensional pattern. This maintains the electromagnetic induction functionality while reducing the thickness to enable portable terminal miniaturization.
Solution Approach 2:
The patent implements the coil on an extremely thin flexible substrate (1-3 μm thick), replacing conventional rigid and thicker wire-based coil structures. This thin-film approach preserves electromagnetic induction capability while enabling the compact form factor required for modern portable terminals.
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 design effectively reduces the thickness of the power-transmission coil, enabling further miniaturization of portable terminals while maintaining efficient electromagnetic induction for charging, by optimizing the magnetic flux and eliminating wire overlaps.
Implementation Method 1
power transmission in a noncontact manner using electromagnetic induction
Implementation Method 2
the counter surface of each coil, which is opposite to the surface facing to the other coil, is entirely covered with a magnetic sheet to prevent undesired radiation with the magnetic field generated from both coils
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A noncontact power-transmission coil is provided. The noncontact power-transmission coil includes a planar coil and a printed-circuit board. The planar coil is formed by spirally winding a linear conductor made of a single or twisted wire in a substantially same plane. The printed-circuit board includes a first external connection terminal portion, a second external connection terminal portion, a first contact portion connected to an inner peripheral end of the spirally-wound linear conductor, a second contact portion connected to the outer peripheral end of the spirally-wound linear conductor, a first conductor pattern connecting the first contact portion to a first external connection terminal portion, and a second conductor pattern connecting the second contact portion to a second external connection terminal portion. One planar portion of the planar coil is attached on the surface of the flexible printed-circuit board.