Watch crystal including a lens and manufacturing method for such a lens
US6406769B1 · kind B1 · utility
49Cited by
4References
8Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Mar 24, 1999 |
| Grant date | Jun 18, 2002 |
| Priority date | — |
| Expiry date | Mar 24, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/219
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
The invention concerns a watch crystal (1) made of hard mineral material, in particular a crystalline material such as corundum, sapphire or spinel, including a non-circular optical lens (4) shaped in the thickness of the material of the crystal. The lens is formed by machining and polishing a recess (5) preferably situated in the lower face (3) of the crystal. Its contour can have reentering angles, and can be for example rectangular. The machining is effected by means of a brush which hits the bottom of the recess with the addition of a polishing medium.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.