Monolithic Silicon Hairspring Assembly for Watch Movements

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Solution Overview

Problem

Classic clock movements face complications and delicate adjustment requirements due to the independent mounting of hairsprings and their components, leading to increased parts and assembly complexity, which affects isochronism and requires benchmarking operations.

Innovation Solution

A one-piece assembly comprising a hairspring, its ferrule, a large plate, and a small plate with a notch, where the components are integrated to form a single unit using silicon etching and micromechanical techniques, allowing precise alignment and reducing the number of parts and assembly operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the hairspring and its ferrule, the large plate and the small plate are mounted separately on the balance staff, then each component can be manufactured independently, but the number of parts increases and delicate adjustment operations are required

Engineering Contradiction:
ImproveIndependent component manufacturingVSAvoidNumber of parts and assembly complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the hairspring, ferrule, large plate, and small plate into a single integrated component manufactured from a monolithic silicon substrate using micromechanical techniques. This eliminates the need for separate mounting operations and reduces the number of parts while maintaining manufacturing precision through single-substrate fabrication.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of operation

If the ferrule of the hairspring is mounted independently on the balance staff, then the hairspring can be installed, but the alignment condition is practically never fulfilled requiring a mobile piton holder

Engineering Contradiction:
ImproveHairspring installationVSAvoidAlignment mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The ferrule is integrated directly with the hairspring as a single monolithic component, eliminating the need for independent mounting and alignment adjustments. The unified structure ensures proper alignment is inherently achieved through the single-substrate fabrication process.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If a mobile piton holder is added to allow rotation for alignment, then the escapement can be aligned properly, but the movement complexity increases and delicate adjustment operations are required

Engineering Contradiction:
ImproveEscapement alignment precisionVSAvoidMovement structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The alignment function is integrated into the monolithic structure itself, eliminating the need for separate mobile piton holders or rotation mechanisms. The precise alignment is achieved through the fabrication process of the single substrate rather than through adjustable mechanical components.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of manufacture

If the hairspring and large plate are mounted independently, then separate manufacturing is possible, but the registration condition is never fulfilled

Engineering Contradiction:
ImproveSeparate component fabricationVSAvoidRegistration precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The hairspring, ferrule, and large plate are fabricated as a single integrated structure from one monolithic silicon substrate using micromechanical techniques. This ensures perfect registration and alignment is inherently achieved through the single-substrate fabrication process, eliminating registration errors from separate mounting operations.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP2570868B1Part for a clockwork, clockwork and timepiece
Publication Date: 2014.09.03 PATEK PHILIPPE SA
  • EP2570868B1 patent drawingFigure 1~2
  • EP2570868B1 patent drawingFigure 3~4
  • EP2570868B1 patent drawingFigure 5~6

AI summary

The clockwork has a plate (1), an anchor bridge (2) and a balance bridge (3) on which a beam axle (5) and an anchor (4) are swiveled. A beam (6) is fixed in the beam axle, and a hairspring (7) is connected with a ring (7.1). A large plate (9) carries an ankle (10), which cooperates with a fork (4.1) of the anchor, and a small plate (8) is provided with a notch, where the small plate cooperates with a dart (4.2) of the anchor. The hairspring, the ring, the large plate, the ankle and the small plate form a single-piece unit.