Reversible Watch Head Assembly for Bottom-Side Battery Access

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Solution Overview

Problem

Existing watch assembly and disassembly methods require alignment in the same direction, limiting flexibility and accessibility, particularly for battery-powered watches that need quick battery access from the bottom.

Innovation Solution

A watch head design allowing assembly from the top and disassembly from the bottom, utilizing a pre-assembled case with a bayonet connection and reversible fastening means, enabling the watch head to be turned over and disassembled/reassembled from the bottom.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the watch head is assembled and disassembled from the top (bezel side), then the assembly process is conventional and straightforward, but the battery access is difficult and time-consuming

Engineering Contradiction:
Improvebattery accessVSAvoidtime for battery replacement
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent inverts the conventional assembly direction by enabling disassembly from the bottom (case back side) rather than the top (bezel side). This allows the movement and dial to be removed from the bottom, providing direct access to the battery compartment without needing to disassemble the entire watch from the top, thus significantly improving battery access efficiency

Inventive Principle:
Principle #13The other way round (Inversion)

2Adaptability or versatility

If the watch head is designed for single-direction assembly, then the structure is simple and conventional, but the watchmaker's freedom and versatility are limited

Engineering Contradiction:
Improveassembly freedomVSAvoidwatch head structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent designs the watch head with universal features that allow it to be assembled and disassembled from both the top and bottom directions. The movement support is mounted on a stop on the underside of the case, and the dial and movement have dimensions that allow them to pass through the case from either direction, providing multi-directional assembly capability and greater versatility for watchmakers

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

3Productivity

If the battery is located in a separate battery compartment in the back, then the watch structure is conventional, but quick battery access is not possible

Engineering Contradiction:
Improvebattery replacement efficiencyVSAvoidbattery accessibility
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent merges the battery compartment with the main watch case structure by securing the battery inside the watch case rather than in a separate back compartment. The movement support is mounted directly to the case underside, and the battery is positioned within the case internal compartment, allowing the battery to be accessed directly when the movement is removed from the bottom

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4707952A1Watch head configured for mounting and dismounting in opposite directions
Publication Date: 2026.03.11 ETA SA MFG HORLOGERE SUISSE
  • EP4707952A1 patent drawingFigure 1A
  • EP4707952A1 patent drawingFigure 1B~2
  • EP4707952A1 patent drawingFigure 3

AI summary

The invention relates to a watch head (1) which can be mounted from the top and dismounted from the bottom, the watch head (1) comprising: - a pre-assembled case (2) having a case middle (3) delimiting an internal compartment (3a), the back (4) mounted with reversible fixing means on said case middle (3) and a movement support (5) mounted to a stop on an underside of the case middle (3), - a movement (7) mounted on the movement support (5) within the pre-assembled case (2), - a dial (8) mounted on the movement (5), - a crystal (10) closing the pre-assembled case (2) at the end opposite the back (4), said dial (8) and said movement (7) having dimensions less than or equal to those of the dimensions of the internal compartment (3a) of the case middle (3) so as to be able to pass through the case middle (3) from the top and from the bottom.