Mechanical Watch Case Cutout for Long-Duration Mainspring Barrels

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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 the movement's outer and inner diameters, which enlarges the case, compromising design and functionality.

Innovation Solution

A mechanical watch design with a circular movement and a case that accommodates a protruding barrel complete via a cutout portion in the inner peripheral portion, allowing the mainspring to have a large diameter without enlarging the case, achieved by incorporating the movement from the side opposite the case back.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If the barrel complete has a large diameter to increase duration, then the mainspring can store more energy for longer operation, but the barrel complete protrudes from the movement requiring an enlarged case

Engineering Contradiction:

Improveoperation durationVSAvoidcase diameter

Core Design Contradiction:

Duration of action of moving objectVSLength of stationary object

Solution Approach 1:

The protruding portion of the barrel complete is nested within the hollow space created by the cutout portion in the case body portion. This allows the barrel complete to have a large diameter for increased duration without requiring the case to be enlarged, as the protrusion is accommodated within the existing case volume through strategic removal of material.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The solution transitions from a two-dimensional planar constraint (case diameter) to a three-dimensional spatial solution by creating a cutout portion that provides vertical and depth accommodation for the protruding barrel complete. This allows the mainspring system to expand in one dimension without proportionally increasing the case footprint in other dimensions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Duration of action of moving object

If the movement diameter is increased to accommodate the protruding barrel complete, then the barrel complete can be larger for longer duration, but both inner and outer diameters of the case must increase

Engineering Contradiction:

Improveoperation durationVSAvoidcase area

Core Design Contradiction:

Duration of action of moving objectVSArea of stationary object

Solution Approach 1:

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

Instead of uniformly increasing the entire case area, the cutout portion creates a localized modification in a specific region of the case body portion. This allows accommodation of the protruding barrel complete while maintaining the original overall case dimensions and minimizing the impact on case area.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250237998A1Mechanical Watch And Method Of Assembling Mechanical Watch

Publication Date: 2025.07.24 SEIKO EPSON CORP

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.