Coloured thermocompensated spiral and a method for the production thereof
US11334025B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 25, 2019 |
| Grant date | May 17, 2022 |
| Priority date | — |
| Expiry date | Nov 13, 2040 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG04B45/0015
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for producing a thermocompensated and coloured coil spring including the steps of forming a first layer of silicon oxide on at least one face of the core and on at least one other face of the core, the first layer having a thickness equal to a fraction of the thickness required for achieving thermal compensation, removing the first layer from at least one face of the core, forming a second layer of silicon oxide on at least one face of the core and on at least one other face of the core, the second layer having a thickness equal to the remaining fraction of the thickness required for achieving thermal compensation which is lower than or equal to 1 μm for giving at least one face of the core a colour as a result of the interference effect.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.