Annular Movement Magnetic Shield for Slimmer Timepieces

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Solution Overview

Problem

Existing timepieces with magnetic shield plates disposed on the case back and outer peripheral side are thick and have a large outer diameter, necessitating a design that reduces thickness and diameter while maintaining magnetic shield performance.

Innovation Solution

The timepiece incorporates a first magnetic shield component with an annular shape disposed inward of the main plate and within the range of the wheel train, and a second magnetic shield component covering the generator, both made of pure iron or permalloy, to form a continuous magnetic path without air layers, reducing the thickness and diameter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If magnetic shield plates are disposed on the case back side and outer peripheral side of the movement, then magnetic shield performance is improved, but the timepiece thickness and outer diameter increase

Engineering Contradiction:

Improvemagnetic shield performanceVSAvoidtimepiece thickness

Core Design Contradiction:

Object-affected harmful factorsVSLength of stationary object

Solution Approach 1:

The magnetic shield component is repositioned from the traditional case back/outer peripheral location to the interior space between the main plate and train wheel bridge, utilizing the vertical dimension (thickness direction) rather than extending the outer diameter. This dimensional repositioning maintains magnetic shielding while reducing overall timepiece size.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The magnetic shield component is nested within the existing movement structure, specifically within the space between the main plate and train wheel bridge. This nesting approach allows the magnetic shield to be integrated into the movement's internal volume without adding external dimensions.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Object-affected harmful factors

If magnetic shield plates are disposed on the case back side and outer peripheral side of the movement, then magnetic shield performance is improved, but the timepiece outer diameter increases

Engineering Contradiction:

Improvemagnetic shield performanceVSAvoidtimepiece outer diameter

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The magnetic shield function is segmented and integrated into specific internal components (first magnetic shield component between main plate and train wheel bridge, second magnetic shield component covering generator) rather than using a single large external shield, allowing compact integration without increasing outer diameter.

Inventive Principle:

Principle #1Segmentation

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 maintains magnetic shield performance while minimizing the timepiece's size by integrating the magnetic shield components within the movement, enhancing compactness and reducing external magnetic field influence.

Implementation Method 1

a first magnetic shield component disposed between the main plate and the train wheel bridge... to form a continuous magnetic path without air layers

Methodology Applied

Scientific EffectMagnetic shielding: Magnetic Field

Data Source

PatentUS12517463B2Time piece having a magnetic shield

Publication Date: 2026.01.06 SEIKO EPSON CORP

AI summary

A timepiece includes a case and a movement disposed in the case, the movement including a main plate, a train wheel disposed at the main plate and including a plurality of toothed gears, a train wheel bridge holding the train wheel, and a first magnetic shield component disposed between the main plate and the train wheel bridge in a side view as viewed from a direction parallel to a surface of the main plate. The first magnetic shield component, in plan view, has an annular shape and is disposed inwardly of an outer periphery of the main plate and, in the side view, is disposed within a range in which the wheel train is disposed. At least a portion of the train wheel is disposed on an inner side of the annular shape in the plan view.