Progressive opthalmic lenses and method of facilitating their manufacture
US5235359A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 15, 1991 |
| Grant date | Aug 10, 1993 |
| Priority date | — |
| Expiry date | Apr 15, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/061
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The front surface, for example, of a progressive ophthalmic lens has a central area whose curvature varies progressively over at least part of at least one meridian and constitutes its optically active area. Surrounding this central area is a peripheral joining area merging tangentially with it. The optically active central area of the front surface is delimited by a closed curve which, when projected onto a plane perpendicular to the geometrical axis of the lens, is generally oval shape. The value and/or sign of the radius of curvature of the radial cross-section of the peripheral joining area varies in the circumferential direction so that the thickness of the lens is substantially the same all along its peripheral edge. Progressive ophthalmic lenses of this kind are easier to manufacture, lighter in weight and more esthetic.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.