Preparation of photochromic gradient lenses
US4155734A · kind A · utility
8Cited by
1References
4Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Nov 7, 1977 |
| Grant date | May 22, 1979 |
| Priority date | — |
| Expiry date | Nov 7, 1997 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29D11/00653
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
Glass lenses or lens blanks, containing all the ingredients necessary to produce phototropic or photochromic behavior, are treated in a conventional production furnace to produce a locally variable heat treatment, wherein at least one portion thereof is raised to a temperature exceeding the glass strain point but not the softening point, and other portions are heated to variable temperatures decreasing from the strain point. The treatment causes development of phototropic or photochromic behavior only in those portions of the lenses or lens blanks exposed to the temperature above the strain point.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.