Moulding contact lenses
US5036971A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 6, 1989 |
| Grant date | Aug 6, 1991 |
| Priority date | — |
| Expiry date | Dec 6, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S425/808
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A polyolefin mould for casting contact lenses from a polymerizable monomer composition which shrinks on polymerization, said mould comprising: male (50) and female (51) mould halves at least one of which has a flexible diaphragm portion (53, 54) which is shaped to provide a surface corresponding to a lenticular surface, said mould halves (50, 51), when closed together, cooperating to define a mould cavity (52) for receiving a volume of said monomer composition, at least one of said mould halves (50, 51) having a shoulder portion (55, 56) surrounding said cavity and shaped to engage with said other mould half to define an edge moulding portion of said cavity: whereby in use said diaphragm (53, 54) is deflected into said cavity under forces exerted on said mould by said monomer composition when polymerized in said closed cavity (52), thereby compensating for the shrinkage occurring on polymerization and avoiding the formation of bubbles or voids in the resulting lenses. In addition, the invention includes a method of casting contact lenses using a mould of the above kind.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.