Watch Case Back Recess and Wedge Opening Without Visible Marks

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Solution Overview

Problem

Existing watch case back separation methods often result in visible damage to the case back, necessitating repair or replacement, leading to additional costs and time for watchmakers.

Innovation Solution

A tool with a specific wedge shape and orientation is used to separate the case back from the case middle, ensuring the mark left by the tool is not visible after reattachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a tool is inserted into the recess to separate the case back from the case middle, then the case back can be opened, but the tool leaves visible marks on the outer edge of the case back

Engineering Contradiction:
Improvecase back separationVSAvoidvisible marks on case back
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The recess is repositioned from the outer edge to the inner edge of the case back, changing the spatial dimension of tool insertion. This allows the tool to act on the case back from a location that will not leave visible marks after reattachment, effectively moving the problem from a surface-level issue to a structurally sound solution.

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

Solution Approach 2:

The invention creates a functional copy of the separation mechanism by providing a recess that accommodates the tool, but positions it differently (at the inner edge rather than outer edge). This copied structure achieves the same separation function while avoiding the harmful effect of visible marks.

Inventive Principle:
Principle #26Copying

2Force

If the recess is positioned at the outer edge to allow tool insertion, then leverage can be applied for separation, but the outer edge is damaged and marked

Engineering Contradiction:
Improveleverage for separationVSAvoidouter edge integrity
Core Design Contradiction:
ForceVSManufacturing precision

Solution Approach 1:

The recess is relocated from the outer edge dimension to the inner edge dimension of the case back. This spatial repositioning maintains the mechanical advantage needed for separation while protecting the outer edge from tool-induced damage and marks.

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

Solution Approach 2:

The recess is positioned at a specific location (inner edge) that has different functional requirements compared to the outer edge. The inner edge location provides sufficient leverage for tool insertion while being hidden or less visible after reattachment, thus maintaining local quality differences between edges.

Inventive Principle:
Principle #3Local quality

3Productivity

If visible marks are left on the case back, then additional repair or replacement operations are required, but this increases cost and time

Engineering Contradiction:
Improveseparation operation speedVSAvoidrepair or replacement time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The recess is pre-positioned at the inner edge during manufacturing, anticipating the need for tool insertion. This preliminary design choice prevents the need for subsequent repair or replacement operations by ensuring the separation process will not create visible marks, thus eliminating future time losses.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention converts what would normally be a harmful location (edge of case back) into a beneficial location for recess placement. By positioning the recess at the inner edge, the area that would traditionally be vulnerable to damage becomes the optimal location for tool access, turning a potential problem into a solution.

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

The tool allows for seamless separation of the case back without leaving visible marks, reducing the need for repairs or replacements and associated costs.

Implementation Method 1

a tool with a specific wedge shape and orientation is used to separate the case back from the case middle

Methodology Applied
Scientific EffectWedge: Wedge

Data Source

PatentEP3971657B1Method for separating a bottom and a middle part together defining a watch case of a timepiece, and timepiece comprising a bottom with a recess suitable for receiving a tool
Publication Date: 2025.12.24 OMEGA SA
  • EP3971657B1 patent drawingFigure 1
  • EP3971657B1 patent drawingFigure 2A~2B

AI summary

The invention relates to a watch component (28) and a tool (20) intended for use by a watchmaker to separate a case back (22) from a case middle (24) which together define a watch case (26) from this watch component (28) inside which a watch movement (30) is housed. This tool (20) has the shape of a wedge, that is to say, a piece of acute shape formed by a first face (20a) and a second face (20b) which intersect at an angle (a) of less than 90° and which are joined to each other by a rounded portion (20c). The first face (20a) of the tool (20) is oriented so that it extends parallel to a mean plane (P) in which the watch movement (30) is located when the watchmaker engages this tool (20) between the base (22) and the case (24) in order to separate this base (22) from this case (24),the rounded portion (20c) connecting to the second face (20b) by a curved portion (20d) whose curvature is directed towards the interior of a surface (20e) delimited by the first and second faces (20a, 20b) the base (22) of the timepiece (28) being delimited externally by a perimeter in at least one place of which is provided a clearance (32) which frees up, between this base (22) and the case (24), a space (34) allowing the watchmaker to engage the end of the tool (20) with which the watchmaker will exert on the base (22) a lever arm to separate this base (22) from the case (24), this clearance (32) comprising a surface (32a) inclined at an acute angle (β) with respect to the average plane (P) when the base (22) is fixed on the case (24),this inclined surface (32a) extending away from the frame (24) towards the bottom of the latter and being extended by a rounded portion (32b) ensuring the connection between the inclined surface (32a) and a lower surface (36) of the base (22).