High speed microfilm searching system

Abstract

A high speed microfilm searching system is disclosed. The system optically displays frames of the microfilm. A frame or column of microfilm is made up of a sensor mark, pages of information and an index code. The index code is a meaningful alphanumeric or numeric key that accompanies each page or column. If it is alphabetic it varies in strict alphabetic sequence. If the components of the key are numeric they vary in an increasing or decreasing order. Microfilm projecting means mounted in the filmpath between feed and take-up reels clearly display on a viewing screen a page of information when the microfilm is stationary in accordance with existing technology. The high speed search system is new technology. A strobe lamp displays indexes of the moving microfilm on a screen. Each of the frames having an index of digital form and also has an optically detectable marker. The marker is placed in a fixed position with respect to the digit positions of the index to insure accurate strobing without the need for masks or shutters. Electronic control means is optically responsive to each marker to generate a marker signal which can trigger the strobe and display the index of that page, like a movie picture. At very low microfilm retrieval speeds each character of the index is legible so that all of the characters of the index can be read by the user. At increasingly high retrieval speeds only more significant characters can be read because of the rapid change of the low order characters. At the increasingly higher speeds the electronic control means may be only responsive to every second, third, fourth, etc. marker signal. As the desired index comes into range, whether going forward or backward, the viewer operator slows the speed of the microfilm so that more of the characters of the index can be read. When the desired index is very close, the film is moved very slowly so that all of the characters of each index can be read. This film is then stopped on the desired frame so that the contents of the page can be read on the viewing screen.

Dependencies are inferred from the claim text.