| 摘要 |
A mechanism for setting an optical system accurately to any of various reproduction ratios comprises at least one carrier which has an optical element or elements mounted thereon and is movable along an optical axis to any selected one of several set positions corresponding to desired reproduction ratios by a buffered four-position pneumatic cylinder having oppositely extending piston rods connected respectively with the carrier and a frame part. The four-position cylinder can be adjusted to set the carrier exactly at the position required for a desired reproduction ratio without affecting the settings that provide other ratios. The carrier may be an objective carrier carrying an objective holder that can be moved relative to it in a plane perpendicular to the optical axis and is so moved as the carrier is moved between its set positions; and a movable part of the objective is adjusted at the same time. A setting mechanism comprising both an objective carrier and a related mirror carrier, each movable along the optical axis by such a four-position pneumatic cylinder to any of several set positions, is advantageous for use in copiers for producing large copies of large originals.
|
