Multi-focal spectacle lens having at least one progressive surface
US4786160A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 5, 1986 |
| Grant date | Nov 22, 1988 |
| Priority date | — |
| Expiry date | May 5, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02C7/066
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention contemplates a multi-focal spectacle lens having two progressive zones which are spatially separated from each other and which provide smooth transition of dioptric power, from one to the next of three different viewing-distance regions. This progressive surface is calculated in accordance with the technique of spline analaysis and is twice continuously differentiable. Such a progressive lens, which is illustratively described for use at computer-screen work stations, has an upper viewing-distance region designed for distant vision, a middle viewing-distance region designed for viewing the computer screen as well as a document arranged alongside the screen, and a lower viewing-distance region designed for near-vision requirements of keyboard operation. Laterally of the near-vision region the power of the lens decreases so that documents lying to the side of the keyboard can also be seen sharply, without moving one's head.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.