Patent GB-734320-A (GB)
Title: Electromagnetic counting device
IPC: G06M1/10
Filed: 1953-05-04
Abstract: 734,320. Counting-apparatus. STANDARD TELEPHONES & CABLES, Ltd. (Kellogg Switchboard & Supply Co.). May 4,1953, No. 12297/53. Class 106 (1). [Also in Group XXXIX] In an electromagnetic counting-device comprising a set of armatures adapted to be operated in turn by successive impulses applied to a single electromagnet, and having magnetic restraining means operating upon those armatures not required to be operated by a particular impulse, the magnetic circuit of said restraining means contains a non-magnetic gap so dimensioned that the restraining flux for an unoperated armature is substantially independent of the number of armatures which have been operated. As shown, the switch comprises a single' eleetromagnet 9, having an oval cross-section, the' major axis being perpendicular to the paper (Fig. 2). The magnet is provided with ten armatures A1 . : . A10 pivoted on a rod 31 and capable when fully attracted of actuating spring sets 5 by moving an insulating member 61 upwards. Two spring members 44, 45 are provided for controlling the armature in conjunction with the applied magnetic forces. The latter merely applies a light upward pressure on the armature 41. The former is capable of being lifted by the end of the armature 41 and thereby lifts its extreme end 46 from its restraining position on a shoulder 47 of an adjacent succeeding armature, the end of the spring being diagonally off-set for this purpose, Fig. 4. The magnet comprises a pole-piece 3 for attracting the armatures and also a further magnetic member 6, connected to' the main polepiece through a small non-magnetic gap 19 dimensioned as above described, and arranged to exert a restraining magnetic force on the armatures, which are, however, prevented from touching the member 6 by a series of adjustable back-stop members 23. The first armature A1 has no restraining spring on its shoulder 47 (there being no preceding armature) nor is it subject to the action of the magnetic restraint from the member 6 which lies opposite only the' armatures A2 A16 so that the armature A1 is held normally in a somewhat' .advanced position by the upward action of its spring 45. When the first impulse is received the armature A1 is attracted to the polepiece 3 but the remainder are held by the magnetic restraining action of the member 6. At the end of the impulse the armature A1 is held, e.g., by residual magnetism. With the restraining influence of the spring 44 removed and the restraining magnetic field also removed the armature A2 is moved into its somewhat advanced position by the upward thrust of its spring 45 in preparation for actuation by the next impulse. Thus after the reception of, say, 6 impulses, all the armatures A1 ... A6 are operated. The mechanism is restored to normal by the application of a small reversing field to the magnet to neutralize the residual magnetism. Instead of relying on residual magnetism a small holding current may be applied to the coil between impulses. Circuit arrangements, Fig. 7. As described the switch is used for selectively lighting one of ten lamps S 1 ... S 10 in accordance with a digit received from the dial CD. Each armature A1 ... A10 has a contact set Cl ... C10 comprising one make contact 64 and one break contact 62. On closure of the line circuit by SK line relay 101 and release relay 102 operate in the normal way and successive impulses are repeated to an operating coil P of the switch. After the actuation of C1 the slow-operating relay 103 is intermittently energized but only operates at the end of the impulse train to complete a lighting circuit for the appropriate lamp over the last-operated make contacts 64 and the succeeding break contacts 62. Relay 103 also prevents further impulses from affecting the switch. When the line circuit is broken, a neutralizing current for the residual magnetism is applied over the release winding R of the switch during the slow release of 103. A modified circuit is described for the case where a slight holding current is maintained between impulses. In this circuit also the operating coil is fed with oppositely-directed current to effect release.