Automatic film focusing by pneumatic servomechanism

Claim 1

IN A PHOTOGRAPHIC APPARATUS FOR RECEIVING FILM HAVING AT LEAST ONE INFORMATION AREA WITH A CORRESPONDING PERIPHERAL NON-INFORMATION AREA AND FOR PROJECTING AN IMAGE THEREOF, SAID APPARATUS INCLUDING: (A) MEANS FOR SUPPORTING SAID FILM; (B) LENS MEANS IN ADJUSTABLE SPACED RELATION TO SAID FILM SUPPORT MEANS FOR FOCUSING SAID IMAGE AT A POINT REMOTE THEREFROM; (C) CHANNEL MEANS COMPRISING A REFERENCE SURFACE POSITIONED IN CLOSE SPACED RELATION TO ONE SURFACE OF SAID FILM TO FORM BETWEEN SAID INFORMATION AREA AND SAID REFERENCE SURFACE A VARIABLE WIDTH CHANNEL HAVING A NARROWED THROAT PORTION; AND (D) MEANS FOR DIRECTING A STREAM OF FLUID THROUGH SAID CHANNEL, THE PRESSURE OF SAID STREAM VARYING AS A FUNCTION OF THE SPACING BETWEEN SAID SURFACES; AUTOMATIC FOCUSING STRUCTURE COMPRISING: (E) AN AIRTIGHT CHAMBER: (F) MEANS FOR PNEUMATICALLY INTERCONNECTING SAID CHAMBER WITH THE THROAT PORTION OF SAID CHANNEL TO EQUALIZE THE PRESSURE THEREBETWEEN; AND (G) RESILIENT MEANS INTERCONNECTING SAID FILM SUPPORT MEANS AND SAID CHAMBER AND RESPONSIVE TO THE PRESSURE WITHIN SAID CHAMBER FOR MAINTAINING A PREDETERMINED SPACED RELATION BETWEEN SAID FILM AND SAID REFERENCE SURFACE, THEREBY MAINTAINING IMAGE FOCUS AT SAID REMOTE POINT.