Watch Balance Spring Anti-Adhesion Surface Reduction
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Solution Overview
Problem
The adhesion of hairspring turns to the bridge in watchmaking micromechanical parts, particularly after shocks, due to contamination or electrostatic charges, affects the isochronism of the oscillator, as seen in insulating materials like silicon and its compounds.
Innovation Solution
An anti-adhesion device is implemented by reducing the potential adhesion surface between the hairspring and the bridge through surface reduction means such as grooves or ribs on either the hairspring or the bridge, limiting the contact area and preventing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the balance spring is made of insulating material (silicon), then manufacturing precision and smoothness are improved, but electrostatic charges form on the surface causing adhesion to the bridge
Solution Approach 1:
A conductive layer is introduced as an intermediary between the insulating balance spring and the bridge. This conductive layer neutralizes electrostatic charges while allowing the balance spring to maintain its insulating material properties for manufacturing precision
Solution Approach 2:
The balance spring becomes a composite structure combining insulating material (for smooth surface and manufacturing precision) with a conductive coating layer (for charge dissipation). This composite approach resolves the contradiction between material properties
2Stability of the object's composition
If the contact surface area between balance spring and bridge is increased, then stability is improved, but adhesion phenomena worsen due to larger potential contact area
Solution Approach 1:
The contact surface is segmented into multiple small discrete contact points rather than a continuous large surface. This segmentation reduces the total potential adhesion area while maintaining sufficient contact for stability through distributed contact points
Solution Approach 2:
The bridge and balance spring surfaces have different local properties: the balance spring maintains smooth surfaces for charge control, while the bridge has localized rough features (protrusions/grooves) that reduce adhesion. Each surface has optimized local quality for its specific function
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
This solution effectively reduces adhesion phenomena, maintaining the isochronism of the oscillator and preventing sticking issues, even in the presence of impurities or lubricants, by minimizing the contact surface area between the hairspring and the bridge.
Implementation Method 1
the opposing faces of the balance spring and bridge offer a much more limited potential adhesion surface, thus reducing these phenomena
Implementation Method 2
the insulating nature of silicon, from which the balance spring is made, allows the formation of electrostatic charges on its surfaces. In some cases, this electrostatic attraction causes the surfaces of the balance spring and the bridge to stick together
Data Source
Figure 1
Figure 2~6
AI summary
The invention relates to a watch movement (1) comprising a resonator (3) formed by the interaction of a balance wheel (5) with a balance spring (7, 7', 7"), said resonator being pivotally mounted between a bridge (2, 2', 2") and another part such as a bridge or a plate (4). According to the invention, the watch movement (1) further comprises an anti-adhesion device (19, 19', 19") for said balance spring against said bridge, comprising surface reduction means (23, 23', 25, 25') formed on the bridge to limit the contact area when the faces (15', 16', 17, 18) of said balance spring and said bridge come into contact.