Patent GB-386994-A (GB)
Title: Improvements in or relating to automatic time indicating apparatus
IPC: H04M3/487
Filed: 1931-07-21
Abstract: 386,994. Automatic exchange systems. BELIN, E., 56, Faubourg St. HonorÚ, Paris. July 21, 1931, No. 20868. [Class 40 (iv).] Photo-electric sound-reproducing apparatus for automatically giving verbal announcements of the time in response to a telephone call comprises in combination a number of photographically recorded transparent rotating discs, means for directing a light beam through portions of these discs successively in a predetermined order, and a photo-electric system for transforming the light variations produced by the discs at any instant into sound, whereby the appropriate announcement is given. The apparatus shown comprises two shafts 5, 6 which are continuously driven at one revolution per second by a shaft 4, itself driven through differential gearing 3 by a synchronous motor M<1>. Each shaft 5, 6 carries two glass discs, 9 .. 12, bearing photographic sound records, in spiral or concentric tracks, of the matter to be announced. The disc 11 serves to indicate the hours (up to twenty-four), the discs 9, 10 have the minute-indicating numbers equally divided between them, while the record on the disc 12 consists in addition to secondindicating numbers, of phrases appropriate to the making of the announcements, with suitable spacing allowing the numbers reproduced by the hour and minute records to be interpolated as necessary. Four discs D<1> .. D<4>, each having a series of spirally distributed apertures, are mounted on tubular shafts, and are arranged adjacent to and concentrically with the discs 9, 10, 12, 11 respectively. The discs D<1>, D<2> are rotated intermittently 1-60th of a revolution per minute, the disc D<4> is rotated intermittently 1-24th of a revolution per hour, and the disc D<3> is driven continuously, making one revolution per minute. Two lamps S<1>, S<2> are so arranged that beams of light passing therefrom through lenses T and through automatically opening and closing shutter systems F are transmitted at the instants when the respective shutters are open, through one or other of the record discs 9 .. 12. The modulated beams are intercepted by the apertured discs D<1> .. D<4>, the position of the aperture in any disc at a. particular instant allowing reproduction only from that part of the record on which the appropriate announcement is recorded. All the light beams are projected by lenses and mirrors L, M on to a single photo-electric cell C, which is adapted to be connected in a sound-reproducing circuit, e.g. automatically through the call of a telephone subscriber. When connection is so made, the time-indication given by the apparatus is at once transmitted telephonically or by wireless. The automatic control of the shutters F is effected by spring-controlled obturating levers l, which are individually actuated by cams c on a shaft 51, rotating once a minute. The levers are oscillated by the cams in a pre-determined order, in order to permit the passage of light through each of the records in turn, and thus to allow the hour and minute announcements given by the records 11 and 9 or 10 to be fitted appropriately into the statements reproduced from the record 12. A special time-signal or " note " is transmitted precisely every half minute by a master clock, warnings of this signal being announced by means of the disc 12. To ensure exact uniformity of speed of the main shaft 4 of the apparatus, the differential gear 3 driven by the motor M<1> is associated with an auxiliary motor M<2>, the operation of which is under the control of a clock 35. The gear 3 comprises a wheel 14 driven by the motor M<1> and carrying planet wheels 15; these mesh with two sun wheels 16, 17, the wheel 16 being keyed to the shaft 4 and the wheel 17 being geared to a worm 20 which is adapted to be driven by the motor M<2> in either direction through one or other of two discs 23 and a roller 27. A contact 36 oscillated by a cam on the shaft 4 co-operates with a contact controlled by the clock 35 to determine when and in what direction a current is sent through electromagnets 29 which control the disposition of the discs 23 relatively to the driving roller 27. When the speed of the shaft 4 is exactly correct, the motor M<2> remains inoperative, but any departure from the standard speed is compensated for by rotation of the wheel 17 in one direction or the other by the action of the motor M<2>.