Antenna Device Current Path Stabilization

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Solution Overview

Problem

The antenna device in existing near field communication systems experiences reduced inductance and varying communication characteristics due to current flow direction discrepancies between the coil conductor and conductive member, leading to degradation in communication performance.

Innovation Solution

An antenna device with a conductive member, a wiring substrate featuring a coupling line, and a connecting conductor that forms a current path, where the conductive member, coupling line, and connecting conductor are electrically connected, and a feeding coil is magnetic-field coupled to the coupling line, optimizing the current path and coupling efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a conductive member with a conductor aperture and slit is used as a radiator in the antenna device, then the antenna can be implemented with a metal plate structure, but the inductance of the antenna is reduced due to current flowing in opposite directions in the peripheral area, causing communication characteristics to degrade

Engineering Contradiction:
Improvestructural strength of metal housingVSAvoidcommunication characteristics
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent extracts the problematic conductive member with aperture and slit from the current path. By removing this specific structure that causes opposite-direction current flow, the invention eliminates the inductance reduction issue while maintaining the metal housing structure for strength.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary structure (the specific arrangement of coil conductor, connection conductors, and conductive member without aperture/slit) that mediates between the metal housing requirement and the inductance maintenance requirement. This intermediary configuration allows current to flow uniformly without creating opposing current paths.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If the coil conductor and conductive member are attached with varying positions or distances, then the assembly is easier to manufacture, but the inductance value varies significantly, affecting communication performance

Engineering Contradiction:
Improveassembly flexibilityVSAvoidinductance value consistency
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent segments the conductive member into a solid plate structure without apertures or slits, eliminating the complex current path issues. This segmentation approach simplifies the structure to a uniform conductive plate that maintains consistent inductance regardless of attachment variations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the geometric parameters of the conductive member by removing apertures and slits, transforming it into a solid plate. This parameter change makes the inductance less sensitive to position and distance variations during assembly, improving manufacturing consistency.

Inventive Principle:
Principle #35Parameter changes

3Area of stationary object

If a metal plate is placed in the vicinity of the antenna coil to serve as a radiator, then the antenna can be integrated into the terminal housing, but the metallic portion shields the antenna and prevents establishment of communication

Engineering Contradiction:
Improveantenna integration areaVSAvoidshielding effect
Core Design Contradiction:
Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful shielding effect into a beneficial radiation function. By using the metal plate as a radiator with optimized current flow paths and eliminating apertures that cause opposite-direction currents, the metal structure that would normally shield the antenna instead becomes the active radiating element.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 stabilizes inductance and enhances communication characteristics by ensuring consistent current flow, reducing variations and improving communication reliability.

Implementation Method 1

a feeding coil disposed on the wiring substrate and magnetic-field coupled to the coupling line

Methodology Applied
Scientific EffectMagnetic-field coupling: Electromagnetic Induction

Data Source

PatentEP3125367B1Antenna device and electronic device
Publication Date: 2019.07.31 MURATA MFG CO LTD
  • EP3125367B1 patent drawingFigure 1~2
  • EP3125367B1 patent drawingFigure 3
  • EP3125367B1 patent drawingFigure 4~5

AI summary

An antenna device includes a conductive member (1) and wiring substrate (2). The wiring substrate (2) includes a coupling line (21) having conductivity. The antenna device includes connecting conductors (3A, 3B) electrically connecting the conductive member (1) and the coupling line (21). A feeding coil (4) magnetic-field coupled to the coupling line (21) is arranged on the wiring substrate (2).