Gradient polarized ophthalmic lens

Abstract

A polarized ophthalmic lens has a polarization gradient with a primary light transmission gradient. The lens also includes a secondary light transmission gradient, the secondary light transmission gradient being complementary to the primary light transmission gradient such that the lens exhibits uniform light transmission.

Claims

1. A polarized ophthalmic lens comprising: a polarization gradient having a primary light transmission gradient; a secondary light transmission gradient; and, said secondary light transmission gradient being complementary to said primary light transmission gradient so as to cause the lens to exhibit uniform light transmission.

2. The polarized ophthalmic lens of claim 1, wherein the ophthalmic lens is a sunglass lens having a uniform light transmission lying in a range of 5 to 80%.

3. The polarized ophthalmic lens of claim 1, wherein the ophthalmic lens is a sunglass lens having a uniform light transmission lying in a range of 10 to 50%.

4. The polarized ophthalmic lens of claim 1, wherein the ophthalmic lens is a sunglass lens having a uniform light transmission lying in a range of 10 to 15%.

5. The polarized ophthalmic lens of claim 2, wherein the ophthalmic lens is a sunglass lens with or without corrective power.

6. The polarized ophthalmic lens of claim 1, wherein: the ophthalmic lens includes a polarized upper region with maximum polarization and a non-polarized lower region with minimum polarization; the ophthalmic lens further includes an intermediate region disposed between said polarized upper region and said non-polarized lower region; and, said intermediate region has a polarization which varies gradually so as to cause the ophthalmic lens to have a lens polarization which varies gradually across the ophthalmic lens from said maximum polarization in said polarized upper region to said minimum polarization in said non-polarized lower region.

7. The polarized ophthalmic lens of claim 6, wherein said maximum polarization lies in the range of 50 to 98% polarization efficiency.

8. The polarized ophthalmic lens of claim 6, wherein said maximum polarization is greater than 90% polarization efficiency.

9. The polarized ophthalmic lens of claim 6, wherein said maximum polarization is greater than 70% polarization efficiency.

10. The polarized ophthalmic lens of claim 6, wherein said maximum polarization is greater than 60% polarization efficiency.

11. The polarized ophthalmic lens of claim 6, wherein said minimum polarization is at least one of in a range of 0 to 50% polarization efficiency, less than 10% polarization efficiency, less than 20% polarization efficiency, and less than 30% polarization efficiency.

12. The polarized ophthalmic lens of claim 1 further comprising a lens substrate configured as one of a thermoset, a thermoplastic and a mineral substrate.

13. The polarized ophthalmic lens of claim 1, wherein said secondary light transmission gradient is provided by a non-polarizing gradient tint.

14. The polarized ophthalmic lens of claim 1, wherein said secondary light transmission gradient is provided by one of a non-dichroic dye and a non-aligned dichroic dye.

15. A process for making a polarized ophthalmic lens having a polarization gradient with a primary light transmission gradient, the lens further including a secondary light transmission gradient, the secondary light transmission gradient being complementary to the primary light transmission gradient so as to cause the lens to exhibit uniform light transmission, the process comprising the steps of: a. forming an ophthalmic lens blank with a polarization gradient with a primary light transmission gradient; b. surfacing the lens blank to produce a corrective power appropriate to a wearer's prescription; c. forming a secondary light transmission gradient by tinting the surfaced lens blank with a complementary non-polarizing gradient tint to provide the lens blank with uniform light transmission; and, wherein the tinted and surfaced lens blank results in an ophthalmic lens having a polarization gradient and uniform light transmission.

16. The process of claim 15 further comprising the step of hard coating one of the lens blank and the ophthalmic lens.

17. The process of claim 15, wherein the polarization gradient is provided by a polarized film formed by inkjet printing a layer of a dichroic dye upon a mordant coating on an oriented film.

18. A process for making a polarized ophthalmic lens having a polarization gradient with a primary light transmission gradient, the lens further including a secondary light transmission gradient, the secondary light transmission gradient being complementary to the primary light transmission gradient so as to cause the lens to exhibit uniform light transmission, the process comprising the steps of: a. forming an ophthalmic finished lens with a polarization gradient with a primary light transmission gradient from a lens blank; b. forming a secondary light transmission gradient by tinting the lens blank with a complementary non-polarizing gradient tint to provide the lens blank with uniform light transmission; and, wherein a finished ophthalmic lens with or without corrective power results having a polarization gradient and uniform light transmission.

19. The process of claim 18 further comprising the step of hard coating one of the lens blank and the ophthalmic lens.

20. The process of claim 18, wherein the polarization gradient is provided by a polarized film formed by inkjet printing a layer of a dichroic dye upon a mordant coating on an oriented film.

21. The polarized ophthalmic lens of claim 1 further comprising a glass lens substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described with reference to the drawings wherein:

(2) FIG. 1A is a schematic illustration of a gradient polarized lens with a typical transmission gradient from top to bottom as shown in the table of FIG. 1B and the chart of FIG. 1C;

(3) FIG. 2A is a schematic illustration of a non-polarizing gradient tinted lens with a typical transmission gradient, but now reversed from bottom to top, as shown in the table of FIG. 2B and the chart of FIG. 2C as it would be produced in a typical gradient tinting process; and,

(4) FIG. 3A is a schematic illustration of an ophthalmic lens in accordance with an embodiment of the present invention, showing a uniform light transmission across the area of the lens, with a gradient polarization, as shown in the table of FIG. 3B and the chart of FIG. 3C.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

(5) In general terms, shown in FIGS. 1A to 1C is a typical gradient polarized lens having a high polarizing efficiency and lower light transmission in its upper region (a) and low polarization efficiency and high light transmission in its lower region (c), with a gradual variation in polarization efficiency across its intermediate region (b).

(6) FIGS. 2A to 2C show a typical gradient tinted (non-polarizing) lens as would be produced in a typical gradient tinting process. The lower region (c) of the lens, which in a preferred manufacturing method remains in a tint bath for the longest time, has the lower transmission and the upper region (a), which is hardly exposed to a tinting solution, has the highest light transmission.

(7) FIGS. 3A to 3C then illustrates an exemplary ophthalmic lens which includes a polarization gradient and a secondary light transmission gradient, the secondary light transmission gradient being complementary to the primary light transmission gradient of the polarization gradient such that the lens exhibits uniform light transmission thereacross, but has a high polarizing efficiency at its upper region and a low polarizing efficiency at its lower region.

(8) Aspects of the invention will now be described with reference to the following examples.

Example 1Plano Sunglass Lenses

(9) A gradient polarized film is produced according to the inkjet printing method described in Trapani et al above. Discs are cut from the film, with the middle of the gradient aligned with notches in a known manner. Discs are bent under the action of heat and pressure to the same curve as the desired lens, and the bent discs are then sandwiched between two glass molds and held at a fixed distance from the front mold by a suitably configured gasket. The spacing between the glass molds is typically 1.8 to 2.2 mm in order to produce a lens suitable for sunglasses with no optical correction.

(10) The sandwiched assembly is then filled with a catalyzed allyl diglycol carbonate monomer and cured over a period of 7 to 21 hours using practices known to those skilled in plastic lens production. After the cure is completed, the lens is removed from the assembly ready to be tinted.

(11) The lens is aligned in a tinting rack and placed in a tinting bath, formulated to produce a complementary gradient color, using techniques known to those skilled in lens tinting processes. However, care is taken to align the lens so that the polarizing axis is perpendicular to the surface of the tinting fluid and so that the polarized portion of the lens is at the top. By tuning the time and depth that the lens is immersed in the tinting bath, a gradient tint of similar color, but which is not polarizing, can be achieved.

(12) In this manner, a lens which has substantially the same light transmission and color from top to bottom, but which has greater than 90% polarizing efficiency in the upper region and low polarizing efficiency in the lower region, can be produced.

Example 2Semi-Finished Blank and Lens with Corrective Power

(13) A gradient polarized film is produced according to the inkjet printing method described in Trapani et al above. Discs are cut from the film with the middle of the gradient aligned with notches in the normal manner. Discs are bent under the action of heat and pressure to the same curve as the desired lens to form a wafer. Bent wafer is then sandwiched between two glass molds and held at a fixed distance from the front mold (desirably <1 mm) in a suitably configured gasket.

(14) The front and back mold of the assembly are arranged to give front surface curve and lens thickness suitable for a desired lens blank, lens blanks being commonly used to produce ophthalmic lenses with corrective power.

(15) The sandwiched assembly is then filled with initiated allyl diglycol monomer and cured using known techniques. After curing, a semi-finished lens is removed from the sandwich and postcured. Postcuring times and temperatures are designed to further cure the lens and relieve internal stresses from previous polymerisation within the mold cavity.

(16) The semi-finished lens is then aligned in a blocking device in a specific orientation to the polarizing axis. It can then be surfaced to prescription power with the polarizing axis oriented vertically in the wearer's spectacle frames. After surfacing, the lenses can be aligned in a rack, with the horizontal axis of the prescription oriented to the surface of the tinting fluid, thus the polarizing axis will be vertical. The tinting time and depth is then managed such that a gradient tint which is complementary to the polarizing gradient is produced.

(17) The finished lens has a substantially uniform transmission and color from top to bottom, has high polarizing efficiency at the upper region of the lens and low polarizing efficiency at the lower region (a reading zone) and has the wearer's corrective power orientated correctly for the wearer's use once fitted to a frame.

Example 3Hi-Refractive Index Lens with Corrective Power

(18) A gradient polarized film is produced according to the inkjet printing method described above in Trapani et al. Discs are cut from the film with the middle of the gradient aligned with notches as is common practice. Discs are bent under the action of heat, pressure and humidity to the same curve as a desired lens to form a wafer. The bent wafer is then sandwiched between two glass molds and held at a fixed distance from the front mold with a suitably configured gasket. The front and back mold of the assembly are arranged to give a curve and thickness suitable for a semi-finished lens blank.

(19) Catalyzed urethane lens monomer is then filled into the mold cavity to encase the polarized film. Urethane lens monomers are known to those skilled in the art of hi-index lens manufacture and include, but are not limited to: thiourethane lens monomer components such as xylylene diisocyanate (XDI), norbornane diisocyanate (NBDI), 2,3 Bis[(2-mercaptoethyl)thio]-1-propanethiol (GST), (bis mercaptomethyl)-3,6,9-trithiaundecane-1,11-dithiol (MR10B), pentaerithritol tetrakis 3-mercaptopropionate (PTMP).

(20) Suitable tin catalysts are used to cure lenses. Such catalysts can include but are not limited to dibutyltin dichloride or dibutyltin dilaurate. Additionally, additives can be included into the lens monomer mix such as UV absorbers and mold release agents known to those skilled in the art.

(21) Filled mold assemblies are then cured in an oven using a temperature program and techniques known to those skilled in the art. Programs and length of cure can vary with desirable cure times being between 20 and 45 hours in order to control the lens cure. After curing the lens is removed from the sandwich and postcured. Postcuring times and temperatures are designed to further cure the lens and relieve internal stresses from previous polymerisation within the mold cavity. The semi-finished lens is then aligned in a blocking device in a specific orientation to the polarizing axis. It can then be surfaced to a prescription power with the polarizing axis oriented vertically for the wearer's normal use. After surfacing, the lenses can be aligned in a rack, with the horizontal axis of the prescription oriented to the surface of the tinting fluid. The tinting time and depth is then managed to produce a gradient tint which is complementary to the polarizing gradient.

(22) The resulting lens has a substantially uniform transmission and color from top to bottom, and has corrective power orientated correctly for the wearer use once fitted to the frame. The lens contains a polarized gradient oriented correctly to suit the wearer, preferably with high efficiency in the upper region of the lens and poor efficiency in the lower region of the lens.

Example 4Polycarbonate Lens with Corrective Power

(23) A gradient polarized film is produced according to the inkjet printing method described above in Trapani et al. The film is bonded between layers of a polycarbonate film using known processes and adhesives. Discs are cut from the film with the middle of the gradient aligned with notches as is common practice. Discs are bent under the action of heat and pressure to the same curve as the desired lens to form a wafer. Bent wafer is then inserted into the molding cavity of an injection molding tool.

(24) Hot molten polycarbonate is injected into the cavity and behind the film, pressing it against the front molding surface of the tool. The mold is allowed to cool and polycarbonate able to solidify and in doing so the film adheres to the polycarbonate lens.

(25) The polycarbonate semifinished polarized lens is removed from the mold and aligned in a blocking device in specific orientation to the polarizing axis. It can then be surfaced to a prescription power with the polarizing axis oriented vertically for the wearer's normal use.

(26) After surfacing, the lens is hardcoated with a tintable hardcoating such as UVNV from UltraOptics. Surfaced, hardcoated lenses can be aligned in a rack, with the horizontal axis of the prescription oriented to the surface of the tinting fluid. The tinting time and depth is then managed to produce a gradient tint which is complementary to the polarizing gradient.

(27) The resulting lens has a substantially uniform light transmission and color from top to bottom, has corrective power orientated correctly for the wearer use once fitted to the frame. The lens contains a polarized gradient oriented correctly to suit the wearer, preferably with high efficiency in the upper region of the lens and poor efficiency in the lower region of the lens.

(28) It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.