Walter S Dougherty

US Patent:

41925840, Mar 11, 1980

Filed:

Aug 15, 1978

Appl. No.:

5/933746

Inventors:

Walter S. Dougherty - Stone Mountain GA

Assignee:

The United States of America as represented by the Department of Health,
Education and Welfare - Washington DC

International Classification:

G03B 2126
G03B 2114

US Classification:

353 30

Abstract:

A system for creating projected visual motion effects for filming or videotaping, with the use of still projection equipment, involves projecting a still image on a screen from a slide projector, projecting a second image on the screen, superimposed on the first image, and causing the projected second image to move rectilinearly at a controlled variable speed and in a selected direction over the first projected still image. This movement is accomplished with a "crawler" assembly having a transparent rectilinearly movable carrier panel carrying the second image over the stage surface of a standard overhead projector, or a light box, constituting the second image light source. The illuminated second image is directed to the screen by an overhead lens and suitably angled mirror. The transparent carrier is driven by a variable-speed reversible motor through a changeable worm gear drive assembly coupled to friction drive rollers engaging the carrier, which is slidably supportingly retained in a guide frame. The guide frame may be disposed at different desired angles over the light box to obtain different desired directions of movement of the projected second image.