Radio Controlled Watch Case Eddy Current Suppression

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Radio controlled watches with metal case bodies and covers experience reduced antenna signal receiving sensitivity due to eddy current flux, and existing solutions either compromise signal sensitivity or water resistance when attempting to suppress eddy currents.

Innovation Solution

Incorporating a spacer member to increase electrical resistance between the case body and cover, combined with a ring member that screws onto the case body to firmly attach the cover, preventing eddy current flux and maintaining strong fixation while ensuring water resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a spacer member is installed between the metal case body and metal back cover to suppress eddy current, then signal receiving sensitivity is improved, but the securing force of the back cover is weakened

Engineering Contradiction:

Improvesignal receiving sensitivityVSAvoidsecuring force of back cover

Core Design Contradiction:

Measurement precisionVSStrength

Solution Approach 1:

The back cover fixing structure is segmented into multiple functions: the spacer member (first fixing member) provides electrical insulation to suppress eddy current, while the ring member with screw threads (second fixing member) provides mechanical securing force. This segmentation allows each component to specialize in one function, resolving the contradiction between signal sensitivity and securing force.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The ring member serves multiple functions: it provides mechanical securing through screw threads, maintains electrical insulation by being formed of non-conductive material, and applies pressing force to ensure waterproofing. This multi-functionality consolidates the fixing mechanism while resolving the contradiction between suppression of eddy current and maintenance of securing force.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If screw heads are cut to suppress eddy current, then signal receiving sensitivity is improved, but the back cover securing force is weakened

Engineering Contradiction:

Improvesignal receiving sensitivityVSAvoidback cover securing force

Core Design Contradiction:

Measurement precisionVSStrength

Solution Approach 1:

The ring member acts as an intermediary between the case body and back cover, providing the screw thread engagement for securing force while maintaining electrical insulation. This intermediary approach eliminates the need to cut screw heads, as the ring member's non-conductive material property suppresses eddy current without compromising mechanical strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If press fitting or screws are used to fix the back cover to the case body, then the back cover is securely attached, but eddy current flux is generated reducing antenna sensitivity

Engineering Contradiction:

Improveback cover attachment strengthVSAvoidantenna signal receiving sensitivity

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

The spacer member and ring member together form an intermediary fixing mechanism that eliminates direct metal-to-metal contact between the case body and back cover. The spacer member provides electrical insulation, while the ring member provides mechanical securing, thereby preventing eddy current generation while maintaining strong attachment.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The fixing mechanism uses composite construction combining non-conductive spacer material with non-conductive ring member material (such as resin or plastic). This composite approach provides both mechanical strength for secure attachment and electrical insulation properties to suppress eddy current, resolving the contradiction between attachment strength and signal sensitivity.

Inventive Principle:

Principle #40Composite materials

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 effectively suppresses eddy current flux, maintaining antenna signal sensitivity and ensuring strong attachment of the cover to the case body while providing high water resistance without the need for cutting screw heads.

Implementation Method 1

eddy current flux can be generated between the case body and the back cover

Methodology Applied

Scientific EffectEddy current: Eddy Currents

Implementation Method 2

a spacer member for increasing the electric resistance between the case body and the cover

Methodology Applied

Scientific EffectElectrical resistance: Electrical Resistance

Implementation Method 3

a ring member, screwed to the case body, for fixing the cover to the case body by pressing the cover against the spacer member

Methodology Applied

Scientific EffectScrew mechanism: Screw

Data Source

PatentUS7639569B2Equipment case, wrist watch case, and radio controlled watch

Publication Date: 2009.12.29 CASIO COMPUTER CO LTD

AI summary

An equipment case for use in an electronic device such as a radio wave wrist watch case comprises a metal case body, a metal back cover, a spacer member, and a ring member. The case body has an opening and houses an antenna inside the case body. The back cover covers the opening of the case body. The spacer member is provided between the case body and the back cover, and increases the electric resistance between the case body and the back cover. The ring member is screwed to the case body, and fixes the back cover to the case body by pressing the back cover against the spacer member towards the case body.