Vacuum suction type film holder

Claim 1

A FILM HOLDER FOR CONVEYING A PHOTOSENSITIVE FILM FROM A DARKROOM TO A CAMERA OUTSIDE THE DARKROOM AND FOR SUBSEQUENTLY EXPOSING THE FILM IN THE CAMERA COMPRISING A GENERALLY RECTANGULAR, SUBSTANTIALLY FLAT CASING PROVIDED WITH A SLIDABLE FRONT SHUTTER PLATE FOR SEALING THE CASING AGAINST THE ENTRY OF LIGHT WHILE A FILM IS BEING CONVEYED IN THE HOLDER, SAID CASING HAVING A REAR WALL, A FLAT BASE PLATE OF MAGNETIC MATERIAL SECURED TO SAID REAR WALL, SAID BASE PLATE BEING FORMED WITH A PLURALITY OF SIMILAR CLOSED-FIGURE GROOVES OF DIFFERNT SIZE, ONE WITHIN THE OTHER AND SPACED TO HAVE SUBSTANTIALLY THE SAME CENTER POINT, SAID GROOVES BEING LOCATED SO THAT THE OUTER CLOSED-FIGURE GROOVE SURROUNDS THE MAJOR PORTION OF THE AREA OF THE BASE PLATE, SAID BASE PLATE BEING FORMED WITH ADDITIOONAL GROOVES INTERCONNECTING SAID SPACED GROOVES, CONDUIT MEANS CONNECTED TO SAID CASING IN COMMUNICATION WITH SAID GROOVES FOR CONNECTING SAID GROOVES TO A VACUUM PUMP, AND A PAIR OF ELONGATED RELATIVELY NARROW PERMANENT MAGNET BARS OF SUBSTANTIAL LENGTH RECEIVABLE IN THE CASING AT OPPOSITE MARGINAL PORTIONS THEREOF FOR CLAMPING THE CORRESPONDING MARGINAL PORTIONS OF A FILM TO SAID BASE SO THAT THE FILM MAY BE SUBSEQUENTLY EXPOSED IN THE CAMERA WHILE BEING CLAMPED TO THE BASE PLATE WITH THE MAJOR PORTION OF THE FILM SUBSTANTIALLY UNOBSTRUCTED BY SAID MAGNET BARS, SAID LENGTH BEING OF THE SAME ORDER AS OPPOSITE MARGINAL PORTIONS OF THE MAGNETIC BASE PLATE, SAID MAGNET BARS COMPRISING FLEXIBLE STRIPS OF RUBBER-LIKE MATERIAL ADMIXED WITH PERMANENTLY MAGNETIZED FERROMAGNETIC MATERIAL.