The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 18, 1978
Filed:
Feb. 18, 1977
John P Bagby, Lake Forest, IL (US);
Erwin E Figge, Des Plaines, IL (US);
Raymond W Kim, Skokie, IL (US);
Bell & Howell Company, Chicago, IL (US);
Abstract
A control for varying the speed of advancement of film is described for use in a film projector in which the film is advanced by a shuttle tooth which engages perforations in the film and advances the film along a path between a light source and a projector aperture. The control includes a rotary shutter assembly having one or more shutter blades for interrupting the light from the light source. As the shutter assembly rotates, the shuttle tooth is reciprocated in the direction of film feed by a rotary cam having one or more cam lobes mechanically coupled to the shuttle tooth. The rotation of the cam lobes is synchronized to the rotation of the shutter blades such that the shuttle tooth is positioned for engagement with the perforations associated with the next successive film frame to be projected whenever a shutter blade interrupts the light source. To engage the shuttle tooth with the film perforations, means are included for sensing the interruption of the light source by the shutter blades to generate a train of pulses, each equal in separation to 1/Nth number of light interruptions, (where N is selectable) and, in response to each pulse, means for advancing the shuttle tooth into engagement with the film perforations so that the film may be advanced by the next motion of the shuttle tooth in the direction of film feed. Thus, the film is engaged and advanced upon each reciprocation of the shuttle tooth when N equals one, and at a selectably slower rate when N is greater than one.