Watch Antenna with Ferromagnetic Core and Resin Layer

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Solution Overview

Problem

Wrist-watch type radio controlled timepieces face challenges in receiving standard waves due to metal exteriors, which hinder magnetic flux entry and reduce antenna sensitivity, and size reduction demands conflict with effective wave reception and time display visibility.

Innovation Solution

A radio-wave receiving device with an antenna featuring a columnar magnetic core, a coil, and separate extension and standing portions made of ferromagnetic materials, where the extension portion is flat-plate shaped and the standing portion is positioned to enhance magnetic flux collection, allowing for improved wave reception without compromising time display visibility or increasing size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If a metal exterior is used for the wrist-watch type radio controlled timepiece, then the aesthetic appearance and high-class feeling are improved, but the receiving sensitivity of the antenna is lowered due to eddy current generation and magnetic flux blocking

Engineering Contradiction:
Improveexterior appearanceVSAvoidreceiving sensitivity
Core Design Contradiction:
ShapeVSReliability

Solution Approach 1:

A resin layer is introduced as an intermediary substance between the metal exterior and the antenna. This resin layer prevents direct contact between the metal exterior and the antenna, thereby blocking the path of eddy currents and preventing the metal exterior from blocking magnetic flux, thus maintaining receiving sensitivity while preserving the aesthetic metal exterior appearance

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The space between the metal exterior and the antenna is segmented by introducing a resin layer, separating the metal exterior from the antenna components. This segmentation prevents the harmful interaction between the metal exterior and the antenna's magnetic field, allowing the metal exterior to maintain its aesthetic function without compromising receiving sensitivity

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If the antenna size is reduced to meet size reduction demands, then the compactness of the timepiece is improved, but the wave reception capability is worsened

Engineering Contradiction:
Improveantenna sizeVSAvoidwave reception capability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The antenna is nested within the watch interior space, with the magnetic core and coil arranged in a compact configuration. The resin layer and other components are nested around the antenna, allowing the antenna to be embedded efficiently within the limited watch space while maintaining its functional dimensions for adequate wave reception

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The antenna structure utilizes three-dimensional spatial arrangement, with the magnetic core forming a compact shape and the coil wound around it. The resin layer extends in multiple dimensions to provide adequate spacing without significantly increasing the overall antenna volume, enabling compact packaging while maintaining reception capability

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If the extension portion and standing portion are integrated into a single component, then the manufacturing process is simplified, but the magnetic flux collection efficiency is reduced

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidmagnetic flux collection efficiency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The antenna is segmented into distinct functional components: the magnetic core, the coil, the extension portion, and the standing portion. Each component is manufactured separately to optimize its specific function, then assembled together. This segmentation allows each part to be precisely engineered for its role in magnetic flux collection while maintaining manufacturing efficiency through modular production

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

While the components are manufactured separately, they are merged into a unified antenna structure through precise assembly. The extension portion and standing portion are positioned relative to each other to create an optimized magnetic flux collection geometry that neither component could achieve alone, combining their functions to enhance overall performance

Inventive Principle:
Principle #5Merging (Combining)

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 configuration significantly enhances antenna sensitivity, enabling effective wave reception even in metal exteriors while maintaining a compact size and clear time display, contributing to the accuracy and spread of radio controlled timepieces.

Implementation Method 1

An electromotive force is obtained at a coil by a magnetic flux transmitted through the bar antenna

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the extension portion and the standing portion are constituted separately, each being made of a ferromagnetic body

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentEP2009518B1Antenna and radio receiver having the antenna
Publication Date: 2018.01.03 CITIZEN WATCH CO LTD
  • EP2009518B1 patent drawingFigure 1
  • EP2009518B1 patent drawingFigure 2(a)~2(c)
  • EP2009518B1 patent drawingFigure 3

AI summary

An antenna that can ensure a sufficient radio receiving level and a radio-wave receiving device on which the antenna is equipped are provided. The antenna of the present invention is constituted by a columnar magnetic core formd by a ferromagnetic body, a coil portion wound around the magnetic core, a flat-plate state extension portion extended from an end portion of the magnetic core, and a standing portion provided at least on a one-direction face of the extension portion. Such antenna is equipped on a wrist-watch type radio controlled timepiece particularly requiring the reduction in size and weight. By this arrangement, while the time display measure is made easier to be seen, the radio controlled timepiece that can ensure the sufficient standard-wave receiving level can be provided.