Patent GB-179538-A (GB)
Title: Improvements relating to machines for printing kinematograph films
IPC: G03B27/16
Filed: 1922-05-02
Abstract: 179,538. Debrie, A. L. V. C. May 2, 1921, [Convention date]. Printing-apparatus.-In a kinematograph film printing machine in which a perforated band is used for changing the printing light and is stepped as the different sections of the film are printed, the mechanism for moving the perforated band is capable of reverse movement in the machine so that the negative can be passed through the machine without rewinding it for printing successive copies. Means are also provided, (1) to cause the printing lamp to remain illuminated at a mean intensity during the change from one intensity to another; (2) to stop the apparatus if the perforated stencil band is inserted wrongly, or when the complete film or a predetermined length thereof has been printed. At the commencement of each section, the edge of the negative film is notched as shown at 55, Fig. 2, so that a roller 56 may make electric contact with a stud 28 on a plate at the printing gate and complete a circuit including an electromagnet 29 driven continuously from a shaft 32 through a reversing clutch 33. The electromagnet and its core 36 carry clutch rings 34, 35, which engage when the electromagnet is energized, and cause the core, together with a disc 37 secured thereto, to rotate with the electromagnet, thereby causing an arm 39 on the disc- 37 to rotate a Maltese cross 41 on the shaft of a drum 42 driving the perforated stencil strip 43. The strip passes between a plate 44 carrying resilient contacts 45 and a plate 48, each contact 45 being adapted to include a different resistance of the rheostat 46 in the circuit of the printing lamp 3 when a perforation 49 on the strip 43 permits it to engage the plate 48. The strip 43 is punched to correspond with the notches 55, so that for each successive section of the film the intensity of illumination of the lamp is appropriate to the exposure required for that section. The disc 37 carries a contact 38 adapted, when the electromagnet 29 is energised, to close a parallel circuit 54 through the lamp and rheostat to pass a current of mean value through the lamp, thereby avoiding abrupt change of the current and consequently sparking at the contacts 45. The reversing gear 33 permits the strip 43 to be driven in the reverse sense, and this together with the provision of a roller 56 on both sides of the film track enables a fresh positive film to be printed without rewinding the negative film. D-shaped holes 50<1>-50<3> are punched in the strip 43, adapted to pass an electric contact 50 on the plate 44 to stop the machine if the strip has been wrongly inserted, through an electric circuit (not shown). Similar holes may be provided at the end of the strip, and at intermediate points, to stop the machine when the whole or a particular length of the negative has been printed. The Specification as open to inspection under Sect. 91 (3) (a)) also includes a construction of printing gate and feed devices in which the negative and positive films 4, 5, Fig. 2 (Cancelled), are fed with their gelatine sides together through a gap between the printing box 1 and the plate 12 hinged thereto. Within the gap they are separated by a plate 11, hinged to the box and against which they are pressed by resiliently mounted rollers 7 acting through apertures 6, 13. On reaching the printing aperture 2 the films are intermittently pressed together by a transparent red glass plate 19 which is pressed by the spring 25 and the films are also further arched by a spring pin 21 which is mounted in a casing 22 hinged to the plate 12 and which is projected through the plate 19 by a spring within the casing 22. This subject-matter does not appear in the Specification as accepted.