Patent EA-002927-B1 (EA)
Title: Improvements in or relating to variable focus lenses
IPC: G02B3/14
Filed: 1997-09-09
Abstract: 1. A method of fabricating a variable focus lens comprising the steps of: engaging a first transparent flexible membrane between the central and one of peripheral rings, a second transparent flexible membrane is engaged between the central and a second peripheral ring, whereby said first and said second flexible membranes define a cavity there between, wherein the position of the first peripheral and the central rings are tensioned by the second peripheral ring holding them. 2. A method as claimed in Claim 1, further comprising the steps of providing a duct through said rings, which duct is in communication with said cavity and filling a transparent fluid into said cavity through said duct. 3. A method as claimed in Claim 2, wherein said duct is formed through said rings. 4. A method as claimed in any preceding Claim, wherein said second peripheral ring receives said peripheral and central rings. 5. A method as claimed in any preceding Claim, further comprising the step of turning, crimping or otherwise deforming the second peripheral ring so that the first peripheral and the central rings are retained within said second peripheral ring. 6. A variable focus lens comprising two flexible transparent membranes, the central and two peripheral rings, wherein the first transparent flexible membrane is engaged between the first peripheral and the central rings, and the second transparent flexible membrane is engaged between the second peripheral and the central rings, wherein the first peripheral and the central rings are tensioned in the second peripheral ring holding them, and a cavity defined by the membranes is filled with transparent liquid. 7. A variable focus lens as claimed in Claim 6, wherein said flexible membranes are held together to retain them under tension and to seal said cavity. 8. A variable focus lens as claimed in any of Claim 6 or 7, wherein said rings are made so that causing the periphery of said transparent flexible membrane to change direction more than once under tension. , 9. A variable focus lens as claimed in any of Claims 6 to 8, wherein the rings cause the periphery of an appropriate flexible membrane to change direction more than once. 10. A variable focus lens as claimed in any of Claims 6 to 9, wherein each of said first and second flexible membranes is of high grade Mylar. 11. A variable focus lens as claimed in any of Claims 6 to 10, wherein each of the rings is of a material which is sufficiently rigid to positively interengage with the adjacent ring and to ensure that two interengaged rings can maintain the flexible membrane under tension. 12. A variable focus lens as claimed in Claim 11, wherein the rings are made of one of a high impact resistant plastics material, aluminium, or titanium. 13. A variable focus lens as claimed in any of Claims 6 to 12, wherein the transparent fluid retained within the cavity is a silicone oil. 14. A variable focus lens as claimed in any of Claim 6 to 13, wherein the lens is additionally provided with two spaced, substantially parallel sheets of transparent polycarbonate between which the cavity defined by the flexible membranes is arranged. 15. A variable focus lens made by a method as claimed in any of Claims 1 to 5. 16. A pair of spectacles having a pair of lens apertures, and a respective variable focus lens as claimed in any of Claims 6 to 15 supported within each lens aperture.