Patent GB-871079-A (GB)
Title: Phasing system for motor driven rotatable members
IPC: H02P5/52
Filed: 1957-11-22
Abstract: 871,079. Electric synchronous movements. CREED & CO. Ltd. Nov. 22, 1957 [Nov. 26, 1956], No. 36409/57. Class 40(3) In a phasing system for two rotating members driven at a synchronous speed by two synchronous motors and in which phasing impulses are produced during the rotation of the said members, means jointly controlled by the pulses operates to disable the energization of one of the motors for periods of time proportional to the phase disparity between the members at the times at which the pulses are compared. In the system described the signals representing the facsimile message are recorded at a central or concentrator office on a magnetic drum 28 driven at one sixth of the rate of a transceiver drum 54 at a station A or B. The end surface of the drum 28 is formed by a brass disc 38 with six insulating segments engaged by a brush 42 connected to the winding I of a relay MP having a biasing winding II which accelerates the release of the relay MP when the circuit of its first winding is opened. When a message on the drum 28 is to be transmitted to a station B the switch 21 is moved to its r. h. position, and if the connecting line L1<SP>1</SP>, L2<SP>1</SP> is free, test relay TR operates. The output of the amplifier 22 is connected to the circuit 17<SP>1</SP> leading to the amplifier 22<SP>1</SP> of the station B, and also to ground 63 via contact 62 operated by cam 56 on the shaft of the transceiver drum 54. The operation of relay TR operates relay P1 which over released contact 2 of relay MC operates relay P2 which is held over one path comprising conductor 82 and operated contact 2 of relay P1 and over a second path comprising its armature 7 conductor 81 and released contact 2 of relay MH. The operation of relay P2 operates relay MRT2 which locks up over ground 48 applied by the circuit 47. Relay MRT2 at armature 1 and released contact of relay MRT1 operates coincidence detecting relay CD which locks up over its armature 2 and contact members 2, 3 of pulsing relays MP, P1 respectively. Operated relay CD at contact 5 holds the carriage feed solenoid 36 in energized condition and also at contact 4 opens conductor 34 to one side of the motor 30. Relay CD also energizes relay MRT1 over contact 2 and holds it energized. When the incoming circuit is opened by contact 62, relay P1 releases and over the released contact 3 and operated contact 6 of relay P2 operates relay MH which effects the release of relay P2 and opens the holding circuit of relay MP which is pulsed by the insulating segments 40 on the disc 38. Relays P1, P2 are again energized when ground 63 is restored by contact member 62. When relay MP releases, it operates motor control relay MC which at contact 3 opens the circuit of the motor 30. The relay MC remains energized firstly over operated contact of relay P2 and then over released contact of relay P1 and the motor 30 is cut off until the interruption of the circuit 17<SP>1</SP> when relays P1, P2 release in turn and when relay P1 reoperates after the interruption, relay MC releases so that the drum 28 is again driven by the motor 30 which soon reaches sychronous speed. At the next release of relay MP, relay MC energizes and locks up with relaysPl and P2 but the motor 30 is cut out for a shorter period. When the local pulse from segment 40 terminates close to the beginning of the pulse interruption from the transceiver, relay MC is not sufficiently fast to operate before the locking circuits provided by relays P1, P2 are broken and the relay has a short delay period so that it does not release until the end of the interruption and at its armature 2 applies a holding circuit after that applied by armature 1 of relay P2 whose release is also delayed until P1 releases so that MC is now held energized under control of P1 and the relay MC releases when relay A is again energized. This short energized period of relay MC causes the motor 30 to slow down until the local and transceiver impulses coincide when the simultaneous removal by relays MP, P of the locking circuits over conductor 78 for the relay CD effects the release of the latter which at contact 4 disassociates the drum motor 30 from control by relay MC.and at contact 5 opens the circuit of solenoid relay 36 which allows the transcriber head 26 to be operatively associated with the drum 28 and to be traversed axially to effect spiral scanning of the drum surface. Specifications 668,865, 673,041, 723,352, 723,373, and U.S.A. Specification 2,606,963 are referred to.