GB872090A - Improvements in or relating to kinematographic apparatus - Google Patents

Abstract

872,090. Kinematograph apparatus. FERNSEH G.m.b.H. Aug. 8, 1958 (Aug. 10, 1957], No. 25490/58. Class 97(1) A clamp is situated adjacent the film gate and is periodically operated to secure and release the film and a difference of air pressure is applied between the convex and concave size of the loop of film preceding said clamp such as to produce in said loop a compressive stress which is resisted by said clamp until its release whereupon said stress causes said film to move rapidly through said gate. In the form shown the film is fed, between sprockets 2 and 14, through the gate 11 and through pneumatic chambers 5, 8 and 12 each chamber consists of a wall such as 6 carrying two other parallel walls adjacent the film edges and between which the film passes. Suction is applied through the aperture 25 to produce a reduced pressure on the film in the chamber 8 so that when a clamp 10 is periodically released by the action of an eccentrically mounted roller 21 on a lever 22 the film is fed through the gate 11. The feed is assisted by the tension in the film produced by the reduced pressure in the chamber 12 caused by the application of suction to the aperture 32. Suction is also applied to an aperture 31 to produce a compressive stress on the loop of film in the antechamber 5 and after each length of film is fed from the chamber 8 to the gate a fresh length of film is fed into the chamber 8 by the release of a clamp 7 by the action of a cam 18 on a roller 19 carried on the arm 20 to which the clamp is attached. The clamp also carries a register pin engaging the film perforations. The reduced pressure in the chamber 8 may be applied continuously, in which case it is less than that applied to the chamber 5, or it may be applied intermittently through an aperture 23 in the rotating disc 24 registering periodically with the aperture 25. The reduced pressures in the chambers 8 and 12 provide components of force tending to hold the film flat at the film gate. Perforated curved members in the chamber 8 determine the maximum and minimum sizes of the film loop therein. A photoelectric device may be provided for scanning register marks on the screen or a mechanical feeler engaging the film perforations. The electrical output of the photocell may be used to correct any irregularities of feed by adjusting an optical member or, where the system includes a cathode ray tube presentation, by adjusting the scanning voltages.