Detachable lens for variable focus spectacles

Abstract

A detachable lens for variable focus spectacles, the lens including a plurality of magnets in a groove on its rear surface for holding the lens to the spectacles. An interlocking boss keeps the lens from sliding off the spectacles, and a locating tab provides a means for assuring that the lens is installed on the spectacles with the proper orientation.

1 . A detachable lens for variable focus spectacles, said spectacles having two lens units, each of which lens units has a magnetizable rim that includes a central opening in its front face having a predetermined size and shape, said detachable lens comprising:
 a lens having front and rear faces;   a plurality of magnets embedded in said rear face; and   a boss on said rear face, said boss having a size and shape enabling it to fit within and interlock with said central opening.   
     
     
         2 . A detachable lens for variable focus spectacles as recited in  claim 1  wherein said magnets are embedded in a groove. 
     
     
         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  and further including a locating tab protruding from the periphery of said 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  and further including a locating tab protruding from the periphery of said 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 comprising:
 a lens having a front face and a rear face;   a plurality of magnets embedded in said rear face of said lens adjacent the periphery of the lens; and   a locating tab protruding from the periphery of said lens.   
     
     
         13 . A detachable lens for variable focus spectacles as recited in  claim 12  wherein said magnets are rare earth magnets. 
     
     
         14 . A detachable lens for variable focus spectacles as recited in  claim 12  wherein said rear face of said lens includes a boss for interlocking with a matching recess on said spectacles. 
     
     
         15 . A detachable lens for variable focus spectacles as recited in  claim 12  wherein said magnets are embedded in a groove in the rear face of said lens.