Mechanical Watch Cutout Structure for Large-Diameter Barrel Accommodation

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Solution Overview

Problem

Mechanical watches with large-diameter mainsprings and many turns to increase duration cause the barrel complete to protrude from the movement, necessitating an increase in both the inner and outer diameters of the case, which is undesirable.

Innovation Solution

A mechanical watch design with a circular movement and a barrel complete that partially protrudes from the movement's outer periphery, featuring a case with an inner cutout to accommodate this protrusion, allowing the movement to be incorporated without enlarging the case's outer dimensions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If the barrel complete is designed with a large number of turns and large diameter to increase duration, then the duration is improved, but the barrel complete protrudes from the movement requiring case diameter increase

Engineering Contradiction:
ImprovedurationVSAvoidcase diameter
Core Design Contradiction:
Duration of action of moving objectVSLength of stationary object

Solution Approach 1:

The invention resolves the contradiction by utilizing the thickness dimension of the case rather than increasing the diameter. The cutout portion is formed in the thickness direction of the case body, allowing the protruding barrel complete to be accommodated vertically rather than requiring horizontal expansion. This dimensional shift enables long-duration operation with large-diameter mainsprings while maintaining compact case outer dimensions.

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

2Adaptability or versatility

If the case diameter is increased to accommodate the protruding barrel complete, then the barrel complete can be accommodated, but both inner and outer diameters of the case increase

Engineering Contradiction:
Improveaccommodation capabilityVSAvoidcase area
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The invention applies dimensional change by forming the cutout portion in the thickness direction of the case body rather than increasing the case diameter. This allows the case to accommodate the protruding barrel complete through vertical accommodation in the thickness dimension, preserving the original case footprint and area while maintaining adaptability to house the extended mainspring.

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

Solution Approach 2:

The cutout portion in the case body creates a nested structure where the protruding barrel complete is received within the case thickness. This nesting arrangement allows the barrel complete to be housed within the existing case boundaries by utilizing the thickness dimension, avoiding the need to increase case area while maintaining accommodation capability.

Inventive Principle:
Principle #7Nested doll (Nesting)

Data Source

PatentEP4589390A1Mechanical watch and method of assembling mechanical watch
Publication Date: 2025.07.23 SEIKO EPSON CORP
  • EP4589390A1 patent drawingFigure 1
  • EP4589390A1 patent drawingFigure 2
  • EP4589390A1 patent drawingFigure 3

AI summary

A mechanical watch using a mainspring as a power source, in which a substantially circular movement is incorporated in a case, wherein a barrel complete storing the mainspring has a protruding portion that partially protrudes from a substantially circular outer periphery of the movement, the case has a case body portion and a bottom portion, and an inner peripheral portion of the case body portion is provided with a cutout portion that accommodates the protruding portion.