Resin Wheel Metal Layer for Static Discharge in Timepiece Movements

The patent applies local quality by providing a metal layer specifically on the tooth tips of the resin wheel rather than throughout the entire wheel. This localized metal coating ensures sufficient conductivity at the critical contact points (tooth tips) where static electricity discharge is most needed, while maintaining the lightweight resin construction of the wheel body. The metal layer is applied only where conductivity is essential for preventing static electricity accumulation during gear meshing.

The patent employs composite materials by combining resin material for the wheel body with a metal layer coating on the tooth tips. This composite structure leverages the advantages of both materials: the resin provides lightweight construction and low moment of inertia, while the metal layer provides the necessary electrical conductivity at the contact surfaces. This composite approach resolves the contradiction by achieving sufficient conductivity without requiring the entire wheel to be made of heavy metal or extensively mixed conductive additives.

The patent applies equipotentiality by making the train wheel bridge conductive through incorporating conductive fibers or particles into the resin material. This ensures that the bridge maintains the same electrical potential as the wheels, preventing potential differences that would cause polarization and Coulomb forces. By equalizing the electrical potential between the conductive bridge and the wheels, the patent eliminates the sticking phenomenon while maintaining the lightweight resin construction of both the bridge and main plate.

The conductive train wheel bridge acts as an intermediary that provides a common electrical potential reference between the wheels and the main plate. By incorporating conductive materials into the bridge, it mediates the electrical interaction between components, preventing direct static electricity accumulation and Coulomb forces between the wheels and the support structure. This intermediary conductive path allows charge dissipation while maintaining the lightweight resin construction.

The patent applies local quality by providing a metal layer specifically on the tooth tips of the thin resin wheel. This localized conductive coating addresses the static electricity problem at the critical contact points without requiring the entire thin wheel to be made of heavy conductive material. The metal layer on the tooth tips provides sufficient conductivity for charge dissipation during meshing, while the thin resin construction maintains low moment of inertia for responsive wheel operation.

The patent applies equipotentiality by making the train wheel bridge conductive, which creates an equipotential environment for the thin wheels. The conductive bridge provides a reference potential that prevents excessive charge accumulation on the thin wheels, even though they are in close proximity to the main plate and bridge. This equipotential condition allows the thin wheels to maintain low moment of inertia while reducing static electricity accumulation through the conductive path provided by the bridge.