Abstract: An automatic high speed microfilm searching system is disclosed for locating a desired frame of microfilm. Each frame consists of information data and index data. The index data comprises a sequence of vertically-aligned data bar groups, each representing a half character of a sequence of characters of a unique index code for the associated frame. A pair of synchronization bars, each half the width of a data bar, is vertically aligned with each data bar group. Additional synchronization pulses both precede and follow the data bar groups. Depending on which direction the microfilm is moving, the leading synchronization bars are sensed by a bar sensing unit on the left or on the right of the viewing screen. Each sensing bar unit comprises a plurality of vertically-aligned data bar sensors and synchronization bar sensors, with three sensors assigned to each vertical bar in a data bar group, and three sensors assigned to reading the synchronization bars.
Type:
Grant
Filed:
April 21, 1981
Date of Patent:
May 15, 1984
Assignee:
Information Retrieval Systems Corp.
Inventors:
Norman N. Axelrod, Peter Haas, Rainer Noess