Zoom mechanism for a reproducing apparatus

Claim 1

A zoom mechanism for a reproducing apparatus wherein an original surface and an image formation surface are fixed, and zooming is effected by moving a lens system between said surfaces, said lens system being mounted on a lens carrier and having two lenseS axially movable relative to each other, wherein the improvement comprises means for correcting for focus shifting during movement of the lens system comprising: a. lever means pivoted to said lens carrier and operatively connected to said two lenses for axially varying the spacing between said lenses upon pivoting; b. cam follower means connected to said pivoted lever means; c. two cam plates, each having an end pivoted at a common point and surface portions cooperating to form a continuous cam surface on which said cam follower means rides so as to pivot said lever means and vary the spacing between said lenses in accordance with said cam surface; d. support means having a pivot thereon on which said two cam plates are mounted at the common point; and e. means for adjusting the orientation of each of said two cam plates with respect to each other about said common point to permit variation of the form of said cam surface to accordingly control the spacing variation between said two lenses during movement of the lens system and correct for focus shifting.