Watch Capsule Bayonet Lock for Secure Battery Access

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Solution Overview

Problem

Existing watch cases with quick-release mechanisms pose a risk of accidental access to the battery compartment, particularly for young children, leading to potential ingestion hazards while maintaining ease of battery replacement.

Innovation Solution

A watch case design featuring a watertight capsule with a bayonet fitting and a lock that prevents relative rotation between the capsule and the case body, ensuring secure access to the battery compartment without specialized tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a quick-release rotating coupling mechanism is used to allow easy battery replacement, then ease of operation is improved, but security against unauthorized access by children deteriorates

Engineering Contradiction:
Improveease of battery replacementVSAvoidsecurity against unauthorized access
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The locking mechanism transitions from a static blocked state to a dynamic unlocked state through rotational movement. The bayonet fitting allows the capsule to rotate relative to the case body, transforming the security state from locked to unlocked, enabling easy access when needed while maintaining security during normal use

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The watch case is divided into separate functional components: a fixed case body and a removable capsule containing the battery. This segmentation allows the capsule to be securely locked in place during normal operation, yet easily removed when battery replacement is needed, resolving the contradiction between security and ease of access

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If a simple slot indentation is provided on the cover for tool insertion, then ease of operation is improved, but security against inadvertent removal by children deteriorates

Engineering Contradiction:
Improveease of cover removalVSAvoidprotection against accidental access
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The coupling mechanism requires a specific rotational motion to disengage, transforming the cover from a statically removable state to a dynamically controlled state. Children can inadvertently press or pull on the simple indentation, but cannot perform the required rotational movement to remove the capsule, thus maintaining security while preserving ease of intentional access

Inventive Principle:
Principle #15Dynamics

3Reliability

If a bayonet fitting with lock is used to prevent relative rotation, then security against unauthorized access is improved, but device complexity increases

Engineering Contradiction:
Improvesecurity of battery compartmentVSAvoidcomplexity of locking mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking function is segmented into the bayonet fitting structure itself, which provides both the coupling and locking mechanisms in a single integrated component. This segmentation avoids adding separate complex locking devices, maintaining simplicity while achieving reliable security against unauthorized access

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bayonet fitting serves multiple functions simultaneously: it provides mechanical coupling between the capsule and case body, enables rotational movement for easy removal, and creates a locked position that prevents accidental opening. This multi-functionality reduces overall device complexity while maintaining high security

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Reliability

If the case back is indexed to the container to prevent relative rotational movement, then reliability of sensor connection is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improveconnection integrity between sensors and movementVSAvoidprecision of indexing alignment
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The case back is pre-indexed to the container during capsule assembly, establishing the correct relative position and orientation before the capsule is installed in the watch case. This preliminary indexing action ensures that sensors and movement connections are properly aligned from the start, maintaining reliability without requiring high precision during final assembly

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The indexing mechanism is segmented into discrete features on the case back and container that mate together to prevent relative rotation. This segmentation provides natural alignment references that reduce manufacturing precision requirements compared to requiring precise positioning of all components during final assembly

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4707954A1Watch case with capsule
Publication Date: 2026.03.11 ETA SA MFG HORLOGERE SUISSE
  • EP4707954A1 patent drawingFigure 1~2
  • EP4707954A1 patent drawingFigure 3~4
  • EP4707954A1 patent drawingFigure 5~7

AI summary

The invention relates to a watch case (1) comprising a case (3), a capsule (2) assembled with a bayonet connection in the case (3) and a lock (16) disposed at the bayonet connection to block any relative rotation between the capsule (2) and the case (3), said capsule (2) comprising: - a container (4) intended to receive a movement and a removable electrical power source, - a back (6) and a crystal (8) respectively closing the container (4) with said back (6) indexed to the container (4) to prevent any relative rotational movement between the back (6) and the container (4), - a sealing gasket (5) between the container (4) and the back (6).