초록

A lens molding system which uses glass molds to mold polycarbonate blanks. The blanks are preheated, then additionally surface heated, molded, and cooled under pressure.

대표청구항 ▼

1. A polycarbonate lens forming device, comprising: an oven, which is programmed to first heat a polycarbonate blank to a specified first temperature below a deformation point of the polycarbonate material and then to heat by an amount effective to raise a temperature of only an outer surface of

1. A polycarbonate lens forming device, comprising: an oven, which is programmed to first heat a polycarbonate blank to a specified first temperature below a deformation point of the polycarbonate material and then to heat by an amount effective to raise a temperature of only an outer surface of the polycarbonate material to a second higher temperature, above the first temperature but below a glass transition point of the polycarbonate material; and a heated pressurized mold, heated to a third temperature higher than said second temperature, and after said outer surface of said polycarbonate material is heated to said second temperature, pressing against surfaces of said polycarbonate material at a pressure less then 450 pounds per square inch. 2. A polycarbonate lens molding apparatus, comprising: first and second glass molds, including a bottom glass mold and a top glass mold, one of said glass molds being concave, and the other of said glass molds being convex, each of said glass molds being in contact with a heat conductance medium which heats the molds to a specified temperature; and said top glass mold including a holding mechanism, rigidly coupled to said lens molding apparatus, having surfaces which hold the top mold in place and limit its downward motion, but which allows the top mold to be pressurized upwards during pressurization. 3. A mold as in claim 2, further comprising a first pressure plate, pressed against said heat conductance medium and a first spring element, providing pressure to said first pressure plate to press said heat conductance medium against one of said glass molds. 4. A method as in claim 3, wherein said first spring is held by a screw. 5. A mold as in claim 3, wherein said first pressure plate presses said heat conductance medium against said top glass mold, and further comprising a second pressure plate, pressed against said heat conductance medium, and a second spring element, providing pressure to said second pressure plate to press said heat conductance medium against said bottom glass mold. 6. A mold as in claim 5, wherein said first and second springs are set to substantially equal pressures, to provide substantially equal pressures at top and bottom glass molds. 7. A mold as in claim 2, further comprising a pressure applying element pressing said first and second glass molds in a direction to keep said molds substantially axially aligned with one another. 8. A mold as in claim 2, further comprising a pressure applying element, pressing said first and second glass molds in a direction which is out of alignment with one another, to maintain one of said glass molds forming an angle with another of said glass molds. 9. A mold as in claim 2, further comprising a pressure applying element, pressing said molds so that they are aligned in a way which forms prizming on at least one of said molds. 10. A method of forming a polycarbonate lens, comprising: obtaining a polycarbonate blank, and heating the polycarbonate blank to a temperature above its glass transition point; further heating surfaces of the polycarbonate blank to further soften said surfaces more than a middle part thereof; and bringing the heated polycarbonate blank into contact with upper and lower heated molds, which are heated to a temperature higher than the surface of the blank, where the molds include a lower mold, where the polycarbonate blank rests against the lower mold, and pressing the upper mold, pressed against the polycarbonate blank. 11. A method as in claim 10, wherein said pressing comprises pressing the upper mold against the lower mold in a direction substantially axially aligned with one another. 12. A method as in claim 10, wherein said pressing comprises pressing the upper mold against the lower mold in a direction which is substantially out of alignment with one another.