Electronically Controlled Mechanical Timepiece Stator Offset

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Solution Overview

Problem

Existing electronically controlled mechanical timepieces face challenges in reducing eddy current loss in main plates made of magnetic materials, which increases the torque required to rotate the rotor and shortens the duration of the mainspring's energy.

Innovation Solution

The timepiece design includes a rotor with a rotor magnet attached to a rotary shaft, a generator with a coil and stator, and a main plate containing magnetic material. The stator's center is positioned farther toward the opposing surface than the rotor magnet's center, allowing for reduced leakage magnetic flux and eddy current loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the main plate is formed using a magnetic material to support the rotor, then the structural strength and support capability are improved, but leakage magnetic flux increases and eddy current loss occurs, increasing the torque required to rotate the rotor

Engineering Contradiction:

Improvestructural strengthVSAvoideddy current loss

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

A nonmagnetic bearing support structure is introduced as an intermediary component between the magnetic main plate and the rotor. This nonmagnetic material acts as a mediator that prevents magnetic flux from leaking into the main plate, thereby eliminating eddy current loss while maintaining structural support functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bearing support structure is specifically positioned only in the region where the rotor interacts with the main plate, creating a localized nonmagnetic zone. This allows the main plate to retain its magnetic properties in other areas while preventing eddy currents only where necessary, optimizing both structural strength and energy efficiency.

Inventive Principle:

Principle #3Local quality

2Power

If the rotor magnet is positioned closer to the main plate to improve magnetic coupling, then power generation efficiency is improved, but leakage magnetic flux to the main plate increases, increasing torque requirements

Engineering Contradiction:

Improvepower generation efficiencyVSAvoidtorque

Core Design Contradiction:

PowerVSForce

Solution Approach 1:

The nonmagnetic bearing support structure serves as a magnetic flux barrier, allowing the rotor magnet to be positioned close to the main plate for efficient power generation while preventing harmful leakage flux from reaching the magnetic main plate. This intermediary structure decouples the magnetic interaction needed for power generation from the harmful eddy current effects.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Power

If the rotor rotates faster to generate more power, then power generation increases, but eddy current loss increases proportionally, consuming more mainspring energy

Engineering Contradiction:

Improvepower generationVSAvoidmainspring energy consumption

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The invention converts the potentially harmful eddy current effect into a beneficial situation by using the nonmagnetic bearing support to eliminate the harmful aspect (energy loss) while preserving the beneficial aspect (power generation). The nonmagnetic material effectively filters out the harmful magnetic flux interactions while allowing the necessary magnetic coupling for power generation to proceed.

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 effectively decreases leakage magnetic flux and suppresses eddy current loss in the main plate, leading to increased duration of the mainspring's energy and improved power generation efficiency.

Implementation Method 1

a generator that includes a coil and a stator and that is configured to generate power by rotation of the rotor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

eddy current loss occurs in the main plate, increasing the torque required to rotate the rotor

Methodology Applied

Scientific EffectEddy current: Eddy Currents

Data Source

PatentUS12332605B2Electronically controlled mechanical timepiece

Publication Date: 2025.06.17 SEIKO EPSON CORP

AI summary

An electronically controlled mechanical timepiece includes: a rotor including a rotary shaft, a pinion that is provided on the rotary shaft and to which torque from a mainspring is transmitted, and a rotor magnet attached to the rotary shaft, the rotor being configured to rotate by the torque; a generator that includes a coil and a stator and that is configured to generate power by rotation of the rotor; a main plate that contains a magnetic material, that has an opposing surface opposed to the stator, and that is configured to support the rotary shaft of the rotor; wherein in a cross-sectional view viewed from a direction perpendicular to an axial direction of the rotary shaft, a center of the stator along the axial direction is disposed farther toward the opposing surface side than a center of the rotor magnet along the axial direction.