Watch Case Back Pin-Groove Locking Mechanism

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Solution Overview

Problem

Existing watch designs face challenges in achieving a watertight and secure assembly of cladding components while also ensuring easy angular indexing and preventing involuntary disassembly.

Innovation Solution

A device for fixing a watch back to a caseband, featuring a ring mounted between the backband and the caseband, with at least one pin secured to the backband that slides in a groove of the ring, allowing for angular indexing and secure locking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a traditional screw or snap-fit mechanism is used to attach the back to the caseband, then the assembly can be securely fixed, but the angular indexing becomes difficult to achieve properly and the sealing may be compromised

Engineering Contradiction:
Improveangular indexing precisionVSAvoidsealing reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The attachment mechanism is segmented into distinct functional elements: the pin for positioning, the groove for guiding rotation, and the seal for waterproofing. This segmentation allows each component to perform its specific function optimally without interfering with others, enabling precise angular indexing while maintaining reliable sealing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The groove acts as an intermediary element between the pin and the caseband, mediating the rotational movement. The pin engages with the groove to guide the back cover into the correct angular position, while the seal independently maintains the waterproof barrier, thus achieving both precise indexing and reliable sealing.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the back is made tightly secured to prevent disassembly, then water resistance and robustness are improved, but involuntary disassembly prevention becomes difficult and after-sales intervention is required for any issues

Engineering Contradiction:
Improvewater resistanceVSAvoidease of disassembly for maintenance
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The attachment mechanism transitions from a static fixed state to a dynamic controlled state. The pin-groove engagement provides a secure locked position during normal use, preventing involuntary disassembly. However, when intentional force is applied during maintenance, the mechanism can be dynamically disengaged, allowing easy removal without compromising water resistance during operation.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If multiple components are used to achieve angular indexing and secure locking, then the precision and reliability are improved, but the device complexity increases

Engineering Contradiction:
Improveangular indexing precisionVSAvoidnumber of components
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Multiple functions are merged into a minimal set of components. The pin simultaneously provides positioning, guiding rotation, and locking functions. The groove combines guidance, rotation control, and engagement features. This merging achieves precise angular indexing and secure locking while minimizing the number of components, thus reducing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4194967B1Device for attaching a bottom on a middle for a timepiece
Publication Date: 2025.05.28 THE SWATCH GRP RES & DEVELONMENT LTD
  • EP4194967B1 patent drawingFigure 1
  • EP4194967B1 patent drawingFigure 2a~2b
  • EP4194967B1 patent drawingFigure 3a~3c

AI summary

A device for attaching a case back to a watch case, the case back having a shoulder forming a cover arranged to fully or partially cover the case and a body arranged to rest within the case, said device comprising at least one pin integral with the case, and a gasket mounted between the case back and the case. According to the invention, the case back comprises, near its periphery, at least one groove, the pin being arranged to slide in the groove between a first position, called the insertion position in which the case back is free, and a second position, called the locking position, in which the case back is locked and positioned angularly relative to the case, and said groove comprising at least one bump to form a resistance point and increase the torque when the pin passes over the bump.