Patent GB-329677-A (GB)
Title: Improvements in and relating to recording and reproducing sound in synchronism with picture taking and projecting apparatus
IPC: G03B31/00
Filed: 1929-02-22
Abstract: 329,677. Holman, H. E., and Columbia Graphophone Co., Ltd., Feb. 22, 1929. Kinematograph apparatus.-Apparatus for projecting motion pictures and reproducing sound comprises means whereby a picture record, having in synchronism with it a sound record, sets into operation when the sound record reaches completion, a successive sound record so that for a short period the two sound records are reproduced simultaneously. If desired there may be provided a. single picture film with a series of sound records set into operation by the film in the desired manner, or a plurality of picture films each having an associated sound record may be provided, and in this case the picture record and sound record of successive machines are adapted to be reproduced simultaneously for a short period. During the simultaneous reproduction of the sound records and picture records, the change-over is made gradual by the provision of suitable means for " fading-in " and " fading- out " the two records. The arrangement during recording is that the picture record blank sets into operation the successive sound record blank so that for a short period two sound record blanks record the same sound passage. An electromagnet clutch g, Fig. 3, may be provided in connection with each sound machine and is operated from the electromagnet g<z> by a pivoted lever g<1>. The circuit of the electromagnet is broken after a limited movement of the clutch by means of a spring finger m having a cam m<1> which is adapted to complete the stroke of the lever g<1> after operation of the electromagnet and thereby separate the contacts m<2> on the lever and frame. The circuit may also be broken by a switch operated by the first revolution of the shaft. The clutch g is released manually when the corresponding sound record has been completed. The electromagnet g<2> may be operated by the picture film in any of the following ways :-(1) a reduction in width of the film i at i<1>, Fig. 4, causes the closure of an electric circuit i4 by means of a spring-controlled pivoted lever i<3>; (2) a portion of the film gate operates under spring action to close the circuit i<4> when a reduced portion of the film passes; (3) the circuit k<4> of the clutch electromagnet is closed by the secondary current from a thermionic relay device k<3>, Fig. 6, which is operated when a deposit of iron provided at the desired part of the film passes a magnet k<1>, having a winding k<2> in the thermionic circuit; (4) a spring-controlled pivoted star wheel l<1> Fig. 8, is adapted to make contact with the main sprocket wheel l<3> engaging the usual perforations of the film when certain enlarged perforations pass between the two wheels. Each picture projector, where a number of such machines is provided, together with its associated sound machine is driven either by a synchronous motor or by a shaft common to each of the machines and rotated by a single motor. Where two cameras are employed for taking the picture, a marking-device in the form of a stylus n<3>, Fig. 9, carried by an armature n<1> of an electromagnet n<2> is adapted to mark a line on the film to indicate the point at which the sound record is set into operation. The completion of the circuit controlling the electromagnet causes a clutch mechanism to start the second soundrecording machine, and this circuit is broken by the spring finger m shown in Fig. 3. The mark serves to indicate the point at which the positive record is to be treated so as to cause the opera. tion of the clutch mechanism. The line may be in the form of a transparent mark which may be utilized as a means for operating the electromagnet clutch mechanism when a beam of light projected from a source o, Fig. 12, on to the edge of the film passes through such transparent line and actuates a light sensitive cell o<1>.