Detachable lens for variable focus spectacles

1. A detachable lens for variable focus spectacles, each pair of said spectacles being comprised of two lens units, wherein each lens unit includes a magnetizable rim that has a front face, including a central opening with a predetermined size and shape in said front face, and each lens unit accepts an associated detachable lens, each of said detachable lenses being unconnected to the other, and each said detachable lens comprising:

a lens having front and rear faces;

a plurality of magnets embedded in said rear face; and

a boss on and a part of said rear face of said lens, said boss having a size and shape enabling it to fit within and laterally interlock with said rim at the perimeter of said central opening.

2. A detachable lens for variable focus spectacles as recited in claim 1 wherein said magnets are embedded in a groove in the rear face of said detachable lens.

3. A detachable lens for variable focus spectacles as recited in claim 2 wherein said magnets are retained in said groove by an adhesive.

4. A detachable lens for variable focus spectacles as recited in claim 1 wherein the two detachable lenses associated with the two lens units of each pair of said spectacles are unconnected parts, and further including a locating tab protruding from the periphery of each said detachable lens.

5. A detachable lens for variable focus spectacles as recited in claim 1 wherein said magnets are rare earth magnets.

6. A detachable lens for variable focus spectacles as recited in claim 5 wherein said magnets are of the type chosen from the group of neodymium iron boron and samarium cobalt magnets.

7. A detachable lens for variable focus spectacles as recited in claim 1 wherein the optical power of said lens units are adjustable between a first predetermined optical power and a second predetermined optical power, and the optical power of said detachable lens is substantially equal to the optical power of the distance prescription of an eye of a specific person minus said first predetermined optical power.

8. A detachable lens for variable focus spectacles as recited in claim 7 wherein said magnets are embedded in a groove in the rear face of said lens.

9. A detachable lens for variable focus spectacles as recited in claim 8 wherein said magnets are retained in said groove by an adhesive.

10. A detachable lens for variable focus spectacles as recited in claim 7 wherein the two detachable lenses associated with the two lens units of each pair of said spectacles are unconnected parts, and further including a locating tab protruding from the periphery of each said detachable lens.

11. A detachable lens for variable focus spectacles as recited in claim 1 wherein said magnets space said detachable lens from said rim so as to provide an air leak.

12. A detachable lens for variable focus spectacles, each pair of said spectacles being comprised of two lens units, wherein each lens unit includes a magnetizable rim that has a front face, including a central opening with a predetermined size and shape in said front face, and each lens unit accepts an associated detachable lens, each of said detachable lenses being unconnected to the other, and each said detachable lens comprising:

a lens having front and rear faces;

a plurality of magnets embedded in said rear face;

a boss on and a part of said rear face of said lens, said boss having a size and shape enabling it to fit within and laterally interlock with said rim at the perimeter of said central opening; and

angular position indicating means in the form of a tab protruding from the periphery of said lens.

13. A detachable lens for variable focus spectacles, each pair of said spectacles being comprised of two lens units, wherein each lens unit includes a magnetizable rim that has a front face, including a central opening with a predetermined size and shape in said front face, and each lens unit accepts an associated detachable lens, each of said detachable lenses being unconnected to the other, and each said detachable lens comprising:

a lens having front and rear faces;

a plurality of magnets embedded in said rear face; and

a transparent boss on and a part of said rear face of said lens, said boss having a size and shape enabling it to fit within and laterally interlock with said rim at the perimeter of said central opening.

14. A detachable lens for variable focus spectacles as recited in claim 13 wherein said magnets are embedded in a groove in the rear face of said detachable lens.

15. A detachable lens for variable focus spectacles as recited in claim 14 wherein said magnets are retained in said groove by an adhesive.

16. A detachable lens for variable focus spectacles as recited in claim 13 wherein the two detachable lenses associated with the two lens units of each pair of said spectacles are unconnected parts, and further including a locating tab protruding from the periphery of each said detachable lens.

17. A detachable lens for variable focus spectacles as recited in claim 13 wherein the optical power of said lens units are adjustable between a first predetermined optical power and a second predetermined optical power, and the optical power of said detachable lens is substantially equal to the optical power of the distance prescription of an eye of a specific person minus said first predetermined optical power.

18. A detachable lens for variable focus spectacles as recited in claim 17 wherein said magnets are embedded in a groove in the rear face of said lens.

19. A detachable lens for variable focus spectacles as recited in claim 18 wherein said magnets are retained in said groove by an adhesive.

20. A detachable lens for variable focus spectacles as recited in claim 17 wherein the two detachable lenses associated with the two lens units of each pair of said spectacles are unconnected parts, and further including a locating tab protruding from the periphery of each said detachable lens.