Patent GB-483098-A (GB)
Title: Improvements in or relating to apparatus for reproducing sound and motion-picture films
IPC: G03B31/00
Filed: 1936-10-16
Abstract: 483,098. Combined kinematograph and sound-reproducing apparatus. WALTER, F. Oct. 16, 1936, Nos. 28205 and 28206. Convention dates, Oct. 16, 1935 and Oct. 8, 1936. [Class 40 (ii)] [Also in Group XX] To enable a kinematograph and soundreproducing apparatus to reproduce films of either standard or narrow width, guiding rollers for the films are stepped to provide surfaces of corresponding width, the guiding surfaces on the rollers being so located that the centre line of the sound track moves over the same part of the sound-reading drum whether the machine is reproducing from narrow or standard width films. The apparatus comprises a picture gate 1 with a picture scanning device, e.g. an optical compensating device 2, and a projector (not shown) ; and a divided _drum 3 housing a photoelectric cell 4 for sound reading by light emitted from an optical system 5. Rollers 6, 7 are provided for guiding the picture film through the picture gate 1, and rollers 9, 10 guide the sound film through the sound gate if separate sound and picture films are used. Combined picture and sound films also may be reproduced. Sprockets 23, 24, 26, film tensioning rollers 11 and guiding rollers 30, 29, 21, 28, 12 are fitted, various sprockets and guiding rollers being selected for use according to the different kinds of film to be reproduced. The rollers 9, 10 and, if desired, the rollers 6, 7 are mounted on ball bearings 15, Fig. 5, and have one diameter 13 for standard films and a reduced diameter 14 for narrow films. The sound drum is in two parts 17, 18, Fig. 4, separated to provide a peripheral slit 19 so that the photoelectric cell 4 is fully exposed to light passing through the film. Fig. 1 shows reproduction effected from a separate narrow sound film and a narrow picture film. The sound film 20 is guided over rollers 29, 21, 9, 10, 12, sprocket 24 and tensioning roller 11. The picture film 22 is guided over the roller 29, sprocket 23, rollers 6, 7, tensioning roller 11 and sprocket 24. The roller 29 is positioned to produce synchronism between the pictures and sound. When reproduction from a standard width sound film and a narrow picture film is required, the sound film is led from the roller 10 to the sprocket 26, the picture film being led over the roller 30, sprocket 23 and gate 1 to be driven by the sprocket 24 as before. A combined sound and picture film is reproduced by leading it to the sprocket 23 over rollers 6, 7 round the tensioning roller 11 to the roller 28 and thence under the roller 9, over the sound reading drum 3, under the roller 10 and round the roller 12 to the sprocket 24. To compensate for the sound track being on the right- or left-hand side of the picture film, an optical reversing device may be interposed in the picture projecting apparatus, so that the picture appears correctly on the screen, such a device being necessary as the film, of whatever type it may be, must always be disposed on the sound drum with the sound track over the slit 19. The optical reversing device may consist of mirrors 38, 40, Fig. 8, equally inclined to the light beam from the projector, and a mirror 39 parallel to the light beam. The projected picture 41 thus becomes the reversed picture 41<1>. Instead of mirrors, a prism may be inserted in the light beam. The optical reversing device may be mounted on a slide or lever, so as to be movable into or out of the light beam as desired.