Balance Spring Conductive Coating for Electrostatic Discharge
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Solution Overview
Problem
Balance springs in watch movements accumulate electrostatic charges, leading to coil sticking and operational issues, and existing discharge methods are inefficient or costly, with potential contamination risks.
Innovation Solution
A unidirectional deposition of an electroconductive layer onto the balance spring, using an atomizer surrounded by a sheathing gas, to electrically connect the outer coil and stud, ensuring partial coverage of the spring's dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroconductive adhesive with conductive particles is used to bond the stud and spiral, then electrostatic charges can be discharged, but the conductive particles hinder the cross-linking of the assembly leading to partial cross-linking and separation of the stud and spiral
Solution Approach 1:
The invention extracts the conductive particles from the adhesive bonding process. Instead of mixing conductive particles with the adhesive, the patent applies a separate electroconductive layer (such as metal vapor deposition, sputtering, or electroplating) onto the bonded stud and spiral assembly after the adhesive has cured. This separation eliminates the interference of particles with the cross-linking process while maintaining the electrostatic discharge function.
Solution Approach 2:
The adhesive bonding is performed first and allowed to fully cross-link and cure before applying the electroconductive layer. This preliminary action ensures that the bond reaches its full strength before any additional materials are applied, preventing the separation issue while still achieving the electrostatic discharge function in a subsequent step.
2Strength
If cross-linking time is significantly increased to ensure complete bonding, then bond strength is improved, but this conflicts with industrial production rates
Solution Approach 1:
The invention replaces the need for extended cross-linking time with an alternative electroconductive solution that can be applied quickly. By using vapor deposition, sputtering, or electroplating to apply the electroconductive layer, the process can be completed in minutes rather than hours, maintaining bond strength while dramatically improving production rate.
3Reliability
If a thin layer of precious metal (gold, platinum, rhodium) is applied to the balance spring surface, then electrostatic charges are eliminated, but additional manufacturing steps are required which are costly and slow down production rates
Solution Approach 1:
The invention uses cost-effective electroconductive materials such as conductive paints, metallic inks, or common metals (silver, copper, aluminum) for the electroconductive layer instead of expensive precious metals. These materials provide sufficient electrostatic discharge functionality at a fraction of the cost and can be applied using simpler, faster processes.
Solution Approach 2:
The invention changes the material parameters from precious metals to more economical conductive materials, and changes the application method parameters from complex multi-step processes to simpler single-step applications such as spraying, dipping, or printing, thereby reducing both cost and production time.
4Reliability
If conductive particles are sprayed onto the adhesive droplet, then electrostatic connection is achieved, but the spraying is not controlled so particles reach the spiral in unplanned locations causing contamination
Solution Approach 1:
The invention uses a controlled electroconductive layer application process (vapor deposition, sputtering, or electroplating) as an intermediary method between the adhesive bonding and the final product. These processes allow precise control of material deposition location and thickness, ensuring that the electroconductive material is applied only where needed without contaminating other parts of the spiral or movement.
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
Effectively eliminates electrostatic charges without altering the spring's characteristics, while being cost-effective and safer for personnel, and avoiding contamination of nearby components.
Implementation Method 1
deposition of at least one first electroconductive layer being carried out by an atomizer in liquid form surrounded by a sheathing gas so as to be unidirectional
Data Source
Figure 1
AI summary
The present invention relates to a method of depositing (500) an electroconductive layer electrically connecting at least one outer coil (105) and a stud (102) and representing at least 1%, in particular 5%, preferably 10% and/or at most 90%, in particular at most 75%, preferably at most 50% of at least one dimension of a watch spiral (101).