Apparatus and method for closure of ophthalmic lens molds

Patent metadata

Field	Value
Publication number	US-9937640-B2
Application number	US-201414576234-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Dec 19, 2014
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

Apparatus and methods for manufacturing ophthalmic lenses by bringing together a pair of mold halves to form a closed mold assembly, are described. The method includes measuring a force applied to bring the mold halves together. The apparatus includes at least one force sensor in operative communication with a single pair of mold halves, and a controller for controlling a velocity of movement of a mold half and for determining when a measured force or average measured force is greater than or equal to a predetermined threshold force.

First claim

The invention claimed is:

1. A method of manufacturing an ophthalmic lens, the method comprising:
providing a male mold half having a convex mold surface, and a complementary female mold half having a concave mold surface, wherein the female mold half retains a polymerizable composition for forming an ophthalmic lens between the convex mold surface and the concave mold surface;
moving one of the mold halves toward the other mold half until the convex mold surface of the male mold half contacts the polymerizable composition retained in the female mold half;
contacting a surface of the female mold half with a surface of the male mold half by applying a force to bring the male mold half and the female mold half together, wherein a velocity at which the male mold half is moved toward the female mold half during the contacting is predetermined based on a previously measured force applied to contact a different pair of mold halves with one another;
measuring the force applied during the contacting; and
determining that the mold halves have formed a closed mold assembly when the force is greater than or equal to a predetermined threshold force.

2. The method of claim 1 , further comprising applying and measuring a moving force during the moving of the one mold half toward the other.

3. The method of claim 1 , wherein at least one of the male mold half and the female mold half is in operative communication with a force sensor during the contacting.

4. The method of claim 3 , further comprising positioning at least one of the male mold half and the female mold half in operative communication with the force sensor before or during the contacting.

5. The method of claim 4 , wherein the positioning comprises positioning at least one of the male mold half and the female mold half in an anvil, wherein the anvil is in operative communication with the force sensor.

6. The method of claim 1 , wherein the velocity at which the male mold half is moved toward the female mold half during the moving, during the contacting, or during both, is from about 0.5 mm/s to about 1.5 mm/s.

7. The method of claim 6 , wherein the velocity at which the male mold half is moved toward the female mold half during the moving is substantially constant for at least 80% of the duration of the moving.

8. The method according to claim 1 , comprising a dwelling stage that includes maintaining the application of the force to the closed mold assembly for a predetermined period of time.

9. The method of claim 8 , wherein the measuring further comprises determining that the force applied during the dwelling stage is greater than or equal to a predetermined threshold dwelling stage force.

10. The method of claim 9 , wherein the predetermined threshold dwelling stage force is about 75 N or more.

11. The method of claim 1 , further comprising a releasing stage that includes releasing the applied force and directing a stream of gas toward and past the mold halves.

12. The method of claim 1 , wherein the method further comprises:
curing the polymerizable composition in the closed mold assembly to form a polymeric lens body; demolding and delensing to release the polymeric lens body from both of the mold halves; optionally washing or extracting or hydrating, or any combination thereof, the released polymeric lens body; placing the released polymeric lens body in a contact lens package; sealing the filled package; and sterilizing the sealed package to form a finished contact lens package.

13. The method of claim 1 , wherein the contacting comprises contacting a plurality of male mold halves with a respective plurality of complementary female mold halves, calculating an average of the forces measured to contact each of the plurality of mold pairs, and wherein the determining comprises determining that that the plurality of pairs of mold halves are acceptably closed when the average of the forces measured is determined to be greater than or equal to a predetermined threshold average force.

14. The method of claim 13 , wherein at least one mold half of each of the plurality of pairs of mold halves is in communication with a separate force sensor and wherein the average of the forces measured is used to determine that the plurality of pairs of mold halves are acceptably closed.

15. The method of claim 14 , wherein the at least one mold half of each of the plurality of pairs of mold halves is positioned in a separate, respective anvil, and each of the separate, respective anvils is in operative communication with a separate, respective force sensor.

16. The method of claim 13 , wherein a variance in an average contact lens diameter of a plurality of finished contact lenses made in accordance with the method is at least 5% lower than a variance in average contact lens diameter of a second plurality of finished contact lenses made in accordance with substantially the same process but wherein that the process used to make the second plurality of finished contact lenses does not include a determining step.

17. A mold closing apparatus suitable for closing one or more contact lens molds, comprising:
an anvil for receiving a female mold half;
a retainer for retaining the anvil in a fixed lateral position;
a force sensor in operative communication with the anvil for measuring a force applied to a female mold half received in the anvil or to a polymerizable composition contained in a female mold half received in the anvil;
a holder for holding and positioning a male mold half that is complementary to the female mold half; and
a controller for controlling a velocity of movement of the holder, and for determining when a measured force applied to bring together a surface of a female mold half received in the anvil and a surface of a complementary male mold half held by the holder, is greater than or equal to a predetermined threshold force, wherein said velocity is predetermined based on the measured force.

18. The mold closing apparatus of claim 17 , wherein the anvil is unrestrained from moving in a vertical direction.

19. The mold closing apparatus of claim 17 , further comprising a plurality of anvils and a respective plurality of force sensors, wherein each of the plurality of anvils is in operative communication with a separate, respective one of the force sensors.

Assignees

• Coopervision Int Holding Co Lp

Inventors

• Gibson John Robert
• Payne Geoffrey Douglas Sydney
• Cook Terence Michael

Classifications

• B29C33/20 Primary

  Opening, closing or clamping · CPC title

• B29D11/00125

  Auxiliary operations, e.g. removing oxygen from the mould, conveying moulds from a storage to the production line in an inert atmosphere · CPC title

• B29L2011/0041

  Contact lenses · CPC title

• B29C2043/5833

  movement of moulds or mould parts, e.g. opening or closing, actuating · CPC title

• B29C43/58

  Measuring, controlling or regulating {(for bank adjustment in calendering B29C43/245)} · CPC title