Apparatus for retrieving microimages

Abstract

Apparatus for retrieving images of microfilms on sheet-like microforms on which the microfilms form frames arranged in vertical and horizontal rows and including larger and smaller frames. A transporting unit can move a microform up or down in a vertical plane so as to place a selected horizontal row of frames in front of a horizontal light source. A carriage in front of the transporting unit supports two lenses which are in line with the light source and respectively serve to project the images of larger and smaller frames onto the screen of a television camera. The carriage is movable horizontally to place a selected lens into register with a selected frame of that horizontal row of frames which is located in front of the light source, and the carriage can transmit motion to a plate- or belt-like diaphragm which is disposed between the transporting unit and the lenses and has one or more apertures registering with that lens which projects the image of a selected frame onto the screen. The device for moving the carriage includes a steel band connected to the carriage and having encoded information which is scanned by one of two photoelectric detectors. These detectors are actuatable alternatively and are respectively associated with the lenses for the projection of images of larger and smaller microfilm frames to arrest the motor for the band when the corresponding lens registers with a selected frame.