Patent GB-987874-A (GB)
Title: Improvements in or relating to devices for automatically controlling the timing of film projection together with the operation of associated apparatus in a film projector system.
IPC: G03B19/18
Filed: 1961-09-14
Abstract: 987,874. Controlling projectors. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. Sept.14, 1961 [Sept. 17, 1960], No. 33000/61. Heading G2E. A device in a film projector system for automatically controlling the timing of film projection together with the operation of associated apparatus comprises the combination of sequential control means for carrying out at least part of said control at preset relative times and a time switch coupled to said sequential control means so as to control said sequential control means at preset absolute times. As shown, the device comprises a time switch A, a control group C and a counting device B. The time switch comprises a unipolar, 60 position switch 1, the pole 2 of which is driven constantly by a synchronous motor 3 which also drives a cam disc 7 having a single cam 8. The switch 1 and other switches 4, 29 and 21-26 to be described hereafter are such that the poles break one connection before making another. The time switch also comprises a 5 polar, 24 contact switch 4, the poles 5 of which are periodically driven by a synchronous motor 6 which also drives a 4-cam disc 9 and has two switches 10 and 11 in parallel in its supply circuit. These switches 10 and 11 co-operate with the cam discs 7, 9 respectively so that the poles 5 are each advanced by one position for every complete rotation of the pole 2. Rotors 5 thus make 1 complete rotation every 24 hours. Rotor 2 is connected to a source of electricity and three rotors of the switch 4 are shown connected to the control group C. Thus, by connecting, for example, the 35- position contact of switch 1 to one of the 6-positions of the switch 4 it can be arranged to send a control signal to a relay of the control group C at 0635 hrs. The control group C is not described in detail but may comprise for example a switching drum controlled by relays and itself controlling such operations as starting up of projectors, switching on and off lights, moving the curtains and providing music before and after a performance. Such an arrangement is disclosed in Specification 711,481. The counting device B comprises a unipolar 48 contact switch 29 and 6 bipolar, 9-contact switches 21-26, the contacts of which are connected together as shown in detail only with respect to switches 29 and 21. The pole 30 of switch 29 is driven by a motor 31 which also drives two 48 cam discs 32, 33 and one 6 cam disc 34. Cam disc 32 controls a switch 35 in the supply circuit of a relay 36 and cam disc 33 controls a switch 37 in the supply circuit of the motor 31. Cam disc 34 controls a switch 38 in a holding circuit of a relay 39. Rotor 30 is connected to one of the contacts of relay 36 and rotors 28 are all connected to a D.C. source of electricity. Rotors 27 of switches 21 and 24 are shown connected to the control group C but in the example of operation following hereafter it will be assumed rotors 27 of switches 21-23 are so connected. Contacts 40, 41 are provided in the supply circuit of the relay 36 and are arranged to be closed by contact strips at the ends of each film. Contacts 42 and 43 are connected to an automatic changeover device not forming a part of the present invention. Summary of operation of the counting device: Assuming, for example, the first part of the programme is to comprise a film of two reels and the second part to comprise a main film of three reels, and, further assuming switches 21 and 22 correspond to the first and second projection systems respectively in the first part of the programme and switch 23 to the projection of the main film, then switches 21, 22 and 23 are respectively adjusted to the 2, 0 and 3 positions. As a result, at the end of the first reel of the first film, the rotor 30 is advanced from the first position (shown) to the second position, and no control pulse is issued. At the end of the next reel however, a control pulse is sent to the control group C, and the rotor 30 is again advanced, but since the third position corresponds to the setting (shown) of the switch 21, the motor 31 continues to rotate the rotor 30 to position 9 which corresponds to a cut in the disc 34 and to the zero setting of switch 22. However, since this switch is set (as shown) in the zero position, the rotor 30 is further rotated to position 17 which corresponds to the next cut in disc 34 and to the zero setting of switch 23. The device now counts the three reels of the zero setting of switch 23. The device now counts the three reels of the main film in a similar manner to the above and sends a pulse to the control group C at the end thereof. A fuller account of the operation is given in the Specification.