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US 5,916,017 AGranted
Preformed ophthalmic lens base block
AssigneeMinnesota Mining and Manufacturing Company
InventorCarole Sedlock
Life of this patent
Estimating the term…
Abstract
The present invention provides novel preformed base blocks that may be used with thermoplastic ophthalmic lens blocking compositions. The preformed base block has a rear portion that is sized and adapted to fit the chuck of a lens processing machine and a front portion that has a negatively tapered peripheral edge. The front portion is adapted to mechanically retain the thermoplastic blocking composition to form a lens block against a lens blank.
Claims17
A preformed base block, comprising:
- a rear portion that is sized and adapted to fit the chuck of a lens processing machine, and
- a front portion having a negatively tapered peripheral edge and a front surface, wherein the negatively tapered peripheral edge of the front portion is angled so as to provide a mechanical overcut and the front portion is adapted to mechanically retain a blocking composition against the negatively tapered peripheral edge to form a lens block against a lens blank.
Dependencies are inferred from the claim text.