Patent GB-191416866-A (GB)
Title: Improvements in or relating to Motion-picture Apparatus.
Inventor: EVANS HENRY RIEGEL
IPC: G03B1/34
Filed: 1914-07-15
Granted: 1915-07-15
Abstract: 16,866. Evans, H. R. July 15. Kinematograph apparatus.-Relates to means for stepping the film in kinematograph apparatus, and of the kind in which the film is stepped by forming a bight in it at one point, whereby another bight at a different point in the film is simultaneously reduced. According to this invention, the stepping movement of the film is completed by the momentum of the film, the bight-forming means exerting tension only during a portion of such movement. Fig. 1 shows an arrangement in which a pneumatic film-stepping device is employed. The film A, after passing through the gate B of a projector, is led through a chamber G, the upper portion of which is closed by a rotary valve C. This valve, Fig. 2, comprises a hollow plug C' provided with suitable ports adapted to co-operate with sets of inlet and outlet ports in a casing D within which the plug is rotated. The inlet ports communicate by a pipe D<6> with a source of compressed air, and the outlet ports discharge over the film in the chamber G. This arrangement is such that, as the valve is rotated by gearing F, which simultaneously operates the upper and lower pairs of sprocket-wheels H engaging with the film, measured puffs of air are intermittently delivered on to the film so as to form a bight at intervals within the chamber G and draw a portion of the film past the gate. The air escapes from the chamber through a port G<1> when the film passes it, the port being so placed and dimensioned that the air pressure fails to complete the stepping movement, which proceeds owing to the momentum of the film until this is stopped by a plate K. In a modified arrangement, instead of delivering compressed air on to the film, suction is applied within the chamber G. Fig. 5 shows a mechanical film-stepping device of the gripper type. The film is intermittently seized and drawn down by a device comprising a gripping- frame M pivoted between the two arms L of a rocker mounted at L'. The rocker is depressed by the engagement of a projection J<2> on a rotating cam J<1> with the transverse bar M<1> of the gripping- frame. The cam leaves the bar M<1> before the rocker strikes a fixed stop L<3>, and the film is thereupon freed and continues its stepping movement by its own momentum. The rocker is lifted after each descent by a lever N<2> operated by an eccentric. The shaft on which the cam J<1> is mounted carries a second eccentric O, which, bv means of a rod O<1> and lever O<3>, applies a pad O<2> to the film during the stepping movement, to control it. Various devices are described for minimizing the shock of impact between the nose J<2> of the cam and the gripping - frame. The mechanism shown in Fig. 13 is of the beater type, and comprises an oscillating member T which intermittently forms a bight in the film by drawing it down into a trough T'. The travel of the beater is so limited as to leave the film to complete each step by its momentum. In another form of beater mechanism, the film is engaged by a polished roller mounted on a spindle which is carried by a two-armed lever. The lever is periodically depressed and lifted by the action of two rotating cams, the roller being caused, by the action of a fixed segmental rack, to rotate upon the film during each descent, so as to draw it down without abrading it. As in the previously - described modifications, the momentum of the film is utilized.