Proximity Antenna Conductive Plate Slit Eddy Current Management

Solution Overview

Problem

Non-contact type IC cards experience degradation in coupling characteristics due to conductive members, such as the metal cabinet of mobile phones, which weakens the magnetic field and affects communication efficiency, and existing solutions like magnetic members are not sufficient or desirable for downsized devices.

Innovation Solution

A proximity type antenna with a conductive plate having an aperture and slit is used, allowing eddy currents to bypass the slit and generate a magnetic field that intensifies the coupling between the antenna and external communication devices, improving coupling characteristics without the need for additional magnetic members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a magnetic member is bonded to the surface of the reader/writer to suppress degradation of coupling characteristics, then the coupling characteristics are improved, but the device size increases and additional components are required

Engineering Contradiction:

Improvecoupling characteristicsVSAvoidadditional magnetic member

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the harmful eddy current effect from the conductive member by introducing slits that interrupt current flow paths. The slits remove the continuous conductive path that causes harmful eddy currents while preserving the structural integrity and shielding function of the conductive member.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention applies local modification to the conductive member by adding slits at specific locations where eddy currents are most harmful. The slits are strategically positioned to interrupt eddy current loops without compromising the overall shielding effectiveness or structural strength of the conductive member.

Inventive Principle:

Principle #3Local quality

2Reliability

If a magnetic member is used to suppress degradation of coupling characteristics, then the coupling characteristics are improved, but the device becomes larger which is not desirable for downsized non-contact type IC cards

Engineering Contradiction:

Improvecoupling characteristicsVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The invention extracts the harmful eddy current effect from the conductive member by introducing slits that interrupt current flow paths. The slits remove the continuous conductive path that causes harmful eddy currents while preserving the structural integrity and shielding function of the conductive member.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the shielding function with the structural component by making the conductive member itself (such as the cabinet) serve dual purposes: providing structural support and blocking external magnetic fields. The slits are integrated directly into the conductive member rather than being separate components.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If a conductive member is arranged near the non-contact type IC card, then structural support and shielding are provided, but eddy currents weaken the magnetic field and degrade coupling characteristics

Engineering Contradiction:

Improvestructural support and magnetic shieldingVSAvoidcoupling characteristics

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention applies local modification to the conductive member by adding slits at specific locations where eddy currents are most harmful. The slits are strategically positioned to interrupt eddy current loops without compromising the overall shielding effectiveness or structural strength of the conductive member.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention converts the harmful eddy current effect into a beneficial configuration by using the slits to redirect eddy currents along paths that no longer form closed loops. The modified current paths reduce magnetic field weakening while the conductive member continues to provide structural support and shielding.

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 solution effectively suppresses the degradation of coupling characteristics by enhancing the magnetic field strength, maintaining communication efficiency even in the presence of conductive members, and does not obstruct the operation of other device components.

Implementation Method 1

the eddy current that arises due to a magnetic field flows, bypassing the slit, and the bypassing electric current generates a magnetic field

Methodology Applied

Scientific EffectEddy current: Eddy Currents

Implementation Method 2

the bypassing electric current generates a magnetic field in a direction of intensifying the magnetic field generated between the proximity type antenna and the external communication device

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentUS8412276B2Proximity type antenna and radio communication device

Publication Date: 2013.04.02 TDK CORP

AI summary

A proximity type antenna includes an antenna pattern for wirelessly communicating with an external communication device by magnetic coupling and a conductive plate arranged near the antenna pattern. The conductive plate has an aperture and a slit extending from the aperture to an end of the conductive plate and at least part of the aperture is arranged at a position of overlapping either the antenna pattern or the region surrounded by the inner periphery of the antenna pattern.