Spiral spring made of athermal glass for clockwork movement and method for making same
AssigneeThe Swatch Group Research and Development Ltd
InventorsThierry Hessler, Joachim Grupp
Life of this patent
Estimating the term…
Abstract
The balance spring is made from a photostructurable glass plate by UV irradiation, thermal treatment and etching, said glass having a Young's modulus thermal coefficient CTE0. The value CTE0 of selected zones of the balance spring are altered to a value CTEi by UV irradiation through one or several masks, possibly completed by a thermal treatment.
Claims24
A glass balance spring including coils of height h and locally a width l, wherein the glass is of a photostructurable type including at least two zones (10, 11, 12, 13) respectively having a different Young's modulus thermal coefficient (CTE0, CTE1, CTE2, CTE3) in order to adapt the mechanical properties of said balance spring selectively.
A method of manufacturing a glass balance spring for a timepiece movement, formed of coils of rectangular cross section of height h, of width I, and having between them a pitch p, wherein it includes the steps of:
- a) taking a photostructurable glass plate (1) of thickness h including a Young's modulus thermal coefficient CTE0;
- b) carrying out UV illumination through a first mask (5, 7) whose windows (5c, 7a, 7b) correspond to the spaces (15) that subsequently have to be released between the coils for structuring at least one balance spring on said plate;
- c) carrying out a high temperature thermal treatment;
- d) creating at least one zone (11, 12, 13) using UV illumination through a second mask (3, 8, 9) over at least one coil whose Young's modulus thermal coefficient one wishes to alter from the initial value CTE0 to a value CTE1, and
- e) carrying out an etch to remove the spaces (15) that have been treated in steps b) and c).
Dependencies are inferred from the claim text.