Lens blocking and constant center thickness system
AssigneeDac S.R.L.
InventorEdward W. Vernon
Life of this patent
Estimating the term…
Abstract
A base lens blocking system comprises a blocking member formed of a flange with a rearward directed shank received in a collet of a spindle, preferably, a dead length, recessed collet. The front surface of the flange contains a lens blank engaging region which can be recessed. The lens blank is applied to the flat, front surface of the flange by means of a disc of adhesive tape, either a thermoplastic adhesive or a double-sided pressure sensitive adhesive tape or a very thin film of wax applied to a heated surface of the flange under a pressure from 5-20 pounds. A batch of blocked lens blanks can be cut with base curves and processed to finished lenses without measuring the center thickness of the base curves of each lens.
Claims20
A blocking member to be engaged by the nose extension of a spindle of a lathe containing a recessed collet for carrying a lens blank in which a base curve is to be formed, said lens blank having a flat rear surface, said blocking member comprising:
- a flange having a diameter larger than the diameter of the collet so as to be able to seat on the forward end of the spindle nose extension, said flange having a forward surface and a rearward surface;
- a collet engaging shank extending rearward from said flange;
- a lens blank receiving region formed in the central portion of said forward surface for receiving said flat rear surface of the blank;
- and
- a reference surface normal to the central axis of the flange for locating the rear surface of the lens blank.
A method of forming a posterior curve in a lens blank having a flat rear surface;
- adhering the flat rear surface of the blank to the center of the front surface of a flange of a first lens blocking member with a film of solid adhesive tape, said flange having a diameter larger than said blank and larger than the spindle of a lathe and said member having a rearwardly extending shank;
- inserting the shank into the spindle of said lathe;
- and
- turning said spindle relative to a cutting tool to form said posterior curve in the front surface of the lens blank.
A lens forming system for forming contact lenses or intraocular lenses from a lens blank comprising in combination:
- a spindle having a bore mounted at its forward end;
- a first blocking member having a flange having rearward facing surface a forward facing flat surface larger than said lens blank and a shank extending from the rearward surface to be received in said collet;
- a means for adhering the inner surface of a lens blank to the center of the flat surface;
- a means for rotating said spindle relative to a cutting tool for forming a base curve and a flat annular reference surface at a known location in the lens blank relative to said inner surface of the lens blank;
- a second blocking member having a first surface complementary to said base curve for engaging the base curve of the lens blank and having a flat annular reference surface complementary to and abutting the annular reference surface and having a rearward directed shank for receipt in the bore of the spindle having a central flange having a diameter larger than said spindle collet and having a forward directed surface and a rearward directed surface;
- and
- means for rotating the spindle relative to a cutting tool to shape the outer surface of the lens blank to form the outer curved surface of a lens.
Dependencies are inferred from the claim text.