Lens selection device

Abstract

A lens selection device for placing any one of three or more magnification lenses in an operative position where its optical axis aligns with a respective reference axis, a selected lens being shifted along a fixed path from a retracted position to the operative position thereof by separate drive means numbering one less than the quantity of the lenses. In the case of three lenses, for instance, a first drive means is used to shift a first lens, a second drive means is used to shift a second lens, and a follower means coupled with a third lens is used to shift it to its operative position when the first (or the second) lens is driven to its retracted position.

What is claimed is: 
     
       1. A lens selection device including three magnification lenses each movably disposed .[.in a direction perpendicular to a single reference axis.]. and adapted to be shifted to a respective operative position .[.on the reference axis.]., characterized in that: two of the lenses are each adapted to be shifted by separate drive means while the third of the three lenses is provided with means to follow the .[.movements.]. .Iadd.movement of at least one .Iaddend.of the aforesaid lenses, said third lens being movable in response to particular .[. movements.]. .Iadd.movement of at least one .Iaddend.of the aforesaid two lenses, whereby a desired one of the three lenses can assume an operative position .[.on the reference axis.]..   
     
     
       2. A lens selection device including first, second and third magnification lenses each having a principal axis and being mounted for movement in an associated path .[.perpendicular.]. .Iadd.relative .Iaddend.to its principal axis, each lens being shiftable along the associated path between a retracted and an operative position, each lens when in its operative position being disposed in an optical path, first drive means coupled to the first lens to shift it as desired, second drive means coupled with the second lens to shift it as desired, the third lens being provided with means effective to cause the third lens to follow the other lenses when either of them are shifted so that the third lens (1) assumes its operative position when the other lenses are in their retracted positions and (2) assumes its retracted position when one of the other lenses assumes its operative position, whereby a desired one of the three lenses can be positioned in its operative position. 
     
     
       3. A lens selection device including first, second, and third magnification lenses each having a principal axis and each being shiftable along a respective, fixed path between respective retracted and operative positions, each lens when in its operative position intersecting a respective, spatially fixed reference axis that coincides with the principal axis of the lens, first drive means coupled to the first lens and selectively operable to shift it between its retracted and operative positions, a second drive means coupled to the second lens and selectively operable to shift it between its retracted and operative positions, and follower means coupled with the third lens and selectively co-operating .Iadd.at least .Iaddend.with the first .[.lens, the.]. .Iadd.or .Iaddend.second lens .[.or both of them,.]. the follower means being effective to shift the third lens from its retracted position to its operative position when one of the other lenses shifts to its retracted position but the remaining one of the lenses stays in its retracted position. 
     
     
       4. The device of claim 3 wherein the third lens is in its retracted position when the first lens or the second lens is in its operative position. 
     
     
       5. The device of claim 3 wherein the follower means includes a spring urging the third lens to its operative position. 
     
     
       6. The device of claim 3 wherein the follower means includes a stop connected to the first lens and engageable with the third lens to keep the third lens in its retracted position when the first lens is in its operative position, the follower means also including a stop connected to the second lens and effectively engageable with the third lens to keep the third lens in its retracted position when the second lens is in its operative position. 
     
     
       7. The device of claim 3 wherein both drive means are simultaneously operable (1) to shift the first lens to its operable position and the second lens to its retracted position, and alternatively (2) to shift the second lens to its operative position and the first lens to its retracted position. 
     
     
       8. The device of claim 3 wherein the reference axis associated with each lens is not coincident with the reference axes associated with the other lenses. 
     
     
       9. The device of claim 3 wherein the reference axis associated with each lens is coincident with the reference axes associated with the other lenses. 
     
     
       10. A lens selection device comprising, in combination, at least three magnification lenses, each lens forming part of an assembly supported for movement along a respective fixed path from/to a position wherein the lens is retracted to/from a position wherein the lens is operative; a plurality of drive means for effecting said movement of the assemblies, there being one less drive means than there are assemblies, each assembly being coupled to a respective one of the drive means except for a particular assembly, each drive means being selectively operable to shift the assembly coupled thereto between the retracted and operative positions; follower means coupled to the aforesaid particular assembly and being operable to shift the particular assembly between the retracted and operative positions thereof in response to movement of any one of the other assemblies from the operative and retracted positions associated therewith; and control means for the drive means adapted to mutually exclusively select a chosen one of the assemblies for shifting into the operative position thereof, said follower means being effective to position the particular lens assembly in the operative position thereof in the absence of selection of any of the assemblies coupled to a drive means. .Iadd.11. A lens selection device comprising a pair of first lenses each of which is movable between operative and retracted positions, drive means for moving each of said first lenses between its operative and retracted positions, a second lens movable between an operative and a retracted position and means motivated by the movement of a first lens toward an operative position for moving said second lens to its retracted position and responsive to the dispositions of both said first lens in their retracted positions for locating said second lens in its operative position. .Iaddend. .Iadd.12. The lens selection device of claim 11 wherein the operative and retracted positions of each of said first and second lenses is respectively in and out of registry with a respective predetermined optical axis. .Iaddend.