Patent GB-1438555-A (GB)
Title: Rotator system including a remote drive motor and a local indicator-control motor
IPC: H04Q9/14
Filed: 1973-07-17
Abstract: 1438555 Automatic control of position RCA CORPORATION 17 July 1973 [24 July 1972] 33976/73 Heading G3N [Also in Divisions H1 and H2] A system for rotating the antenna mast of a television set and providing a local indication of its rotated position comprises a split-phase A.C. induction motor 31 driving through a gear train 33 the shaft 35 of the mast and a cam 45 controlling a changeover switch 47, which members form a remote rotator drive unit 11 connected to a local control and indicator unit 13 consisting of a transformer 21 whose primary winding 23 is controlled by an on/off switch 27 respectively opened or closed when indicator and control discs 53, 54 are aligned or misaligned, changeover switches 43, 61 controlled by a cam 87, a D.C. motor 51 coupled by a gear train 52 to the disc 53 and to a cam 55 controlling a changeover switch 71 and oppositelypoled diodes 65, 67 the various circuit elements being connected such that clockwise or anticlockwise rotation of the disc 54 closes switch 27 and pairs of contacts of the switches 43, 61 to produce continuous energization of the motor 31 and intermittent energization of the motor 51 until the latter has driven the disc 53 back into alignment with disc 54 to open switches 27, 43, 61. During a typical rotation of the motor 31, the switches 47, 71 interact with one another and with the rotation of cams 45, 55 to connect to the terminals 51a, 51b of the motor 51 either of the phase potentials on leads 17, 19, the switch 47 directly connecting the lead 17 or 19 to the terminal 5 1a and the switch 71 connecting the lead 17 or 19 to terminal 51b through that one of the diodes 65, 67 selected by the switch 61 in response to the direction of rotation of the disc 54 to connect contact 66a to contact 64a or 68a. When the same lead 17 or 19 is connected to each terminal 51a, 51b the motor 51 is not energized, but when different leads are connected the motor is energized and rotates in a direction determined by  members 54, 61, 65, 67 and corresponding to that  for the motor 31 determined by which contact pair 41a, 44a or 42a, 44a of switch 41 is closed by the movement of disc 54. When the disc 54 is rotated to move the shaft 35, the motor 31 runs with the motor 51 stationery until contact 49a leaves cam face 45a to engage contact 48a, the motor 51 then running until contact 72a leaves cam face 55a to engage contact 73a, further alternate switching on and off of the motor 51 being produced by the subsequent movement of cams 45, 55. The speeds of motors 31, 51 and the gear ratios between them and their driven members are chosen to compensate for the different energization patterns of motors 31, 51 and so produce overall synchronization of members 35, 53. The cam 87 comprises an arcuate member having two slots respectively receiving the contacts 44a, 66a, the member being rotatable about the disc 54 to move these contacts in opposite directions when a toothshaped member integral with the arcuate member is forced from a slot 89 in disc 53 by movement of the disc 54, Figs. 2, 3 and 4 (not shown).