Method for forming optical lenses

• US 4,197,266 A
• Filed: 11/21/1977
• Issued: 04/08/1980
• Est. Priority Date: 05/06/1974
• Status: Expired due to Term

• Current Assignee: Bausch & Lomb Incorporated (Bausch Health Cos., Inc.)
• Original Assignee: Bausch & Lomb Incorporated (Bausch Health Cos., Inc.)
• Inventors: Clark, James A., Wrue, Richard J., Livesey, Donald V.
• Primary Examiner(s): Lowe, James B.
• Application Number:
  US05/853,701
• Time in Patent Office: 869 Days
• Field of Search: 264/1, 425/808
• US Class Current: 264/2.2
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 33/0038 with sealing means or the like seals on envelopes used in tyre retreading B29D30/542; for injection moulding footwear B29D35/0045
• CPC Class Codes: B29C 33/303 centering mould parts or halves, e.g. during mounting
• CPC Class Codes: B29C 35/0894 provided with masks or diaphragms
• CPC Class Codes: B29C 37/005 Compensating volume or shape change during moulding, in general
• CPC Class Codes: B29C 43/021 characterised by the shape of the surface
• CPC Class Codes: B29C 43/38 with means to avoid flashes B29C43/40 takes precedence
• CPC Class Codes: B29D 11/00009 Production of simple or compound lenses
• CPC Class Codes: B29D 11/00038 Production of contact lenses
• CPC Class Codes: B29D 11/00442 Curing the lens material
• CPC Class Codes: B29D 11/0048 Moulds for lenses moulds for plastic articles in general B29C33/00
• CPC Class Codes: B29D 11/00942 where the lens material is mounted in a support for mounting onto a cutting device, e.g. a lathe, and where the support is of machinable material, e.g. plastics
• CPC Class Codes: B29K 2105/0002 monomers or prepolymers
• CPC Class Codes: B29L 2011/0016 Lenses
• CPC Class Codes: B29L 2031/7602 Maps

Abstract

Apparatus for and method of forming ophthalmic lenses and/or semi-finished lens blanks including those of the eye contact type. The apparatus includes molds having cooperating first and second members each of which includes a longitudinal axis and a mold surface which is symmetrical with respect to such axis. In one embodiment these mold members or halves also include cooperating surfaces which, in operation and in cooperation with the selected lens material, both align the respective mold axes and axially position the mold surface of the first member with respect to the mold surface of the second member to thereby form the desired lens mold cavity. Further, each of the assembled molds also includes an annular reservoir which surrounds the mold cavity and is defined by surfaces provided on the first and second mold members. This reservoir is connected to the mold cavity via an annular restriction. In one embodiment this restriction is defined by the cooperating aligning surfaces provided on the first and second mold members.

In operation, the reservoir holds a volume of lens material which, during the polymer forming reaction, is kept in a flowable state longer than the lens material in the mold cavity. This arrangement permits the transfer of lens material between the reservoir and the mold cavity during curing. Apparatus is also provided for removing selected portions of the cast lens in those instances where removal is either necessary or expedient.

Claims

1. A method of forming a lens from first and second mold members, said first mold member having a first longitudinal axis and a first mold surface referenced with respect to said first longitudinal axis, said second mold member having a second longitudinal axis and a second mold surface referenced with respect to said second longitudinal axis, said mold surfaces cooperating to define a mold cavity having a center section and an edge portion, said mold members defining, when said second mold member is assembled with said first mold member, an annular reservoir surrounding said mold cavity and connected to said mold cavity by an annular restriction, said annular restriction being defined by first and second axial spacing means and first and second radial alignment means located on said first and second mold members between said reservoir and said mold cavity, said method comprising:

(a) orientating said first mold member so that said first mold surface will retain polymerizable material;

(b) depositing on said first mold surface a volume of polymerizable material in excess of the volume of the lens to be formed;

(c) moving said second mold member into position relative to said first mold member to form both said mold cavity and said annular reservoir, said second mold surface contacting said polymerizable material on said first mold surface to force said polymerizable material outward to;

(1) fill said mold cavity with a portion of said polymerizable material;

(2) space both said first axial spacing means from said second axial spacing means and said first radial alignment means from said second radial alignment means by a layer of polymerizable material to form said restriction and to both axially position said first mold surface relative to said second mold surface and hydrostatically align said axis; and

(3) load said reservoir with that portion of said polymerizable material which is in excess of the volume of said mold cavity and said restriction; and

(d) polymerizing said polymerizable material in said mold cavity from said center section of said mold cavity to said edge portion of said mold cavity.

2. The method as set forth in claim 1 further including the steps of:

(a) providing machine referencing means on one of said first and second mold members;

(b) disengaging said first and second mold members so as to leave the polymerized material adhering to said one of said first and second mold members;

(c) providing a contouring apparatus including a cutting means and a rotatable chuck provided with a centering means;

(d) positioning said polymerized material relative to said cutting means by engaging said machine referencing means with said centering means;

(e) rotating said chuck; and

(f) engaging said cutting means with said polymerized material to remove selected portions thereof.

3. The method as set forth in claim 1 wherein said polymerization step is accomplished by subjecting said center section of said mold cavity to a greater quantity of polymerization including radiation than said edge portion of said mold cavity.

4. The method as set forth in claim 3 further including the steps of:

(a) providing means for shielding said edge portion of said mold cavity;

(b) directing polymerization inducing radiation onto said center section of said mold cavity and said shield means until said polymerizable material in said center section of said mold cavity is at least partially cured; and

(c) removing said shield means to thereby permit said radiation to polymerize said polymerizable material in said edge portion of said mold cavity.

5. The method as set forth in claim 4 further including the steps of:

(a) providing machine referencing means on one of said first and second mold members;

(b) disengaging said first and second mold members so as to leave the polymerized material adhering to said one of said first and second mold members;

(c) providing a contouring apparatus including a cutting means and a rotatable chuck provided with a centering means;

(d) positioning said polymerized material relative to said cutting means by engaging said machine referencing means with said centering means;

(e) rotating said chuck; and

(f) engaging said cutting means with said polymerized material to remove selected portions thereof.