GB1451451A - Selective electrical switching means - Google Patents

Abstract

1451451 Co-ordinate selectors; electromagnetic relays UNIVERSAL TELEWRITERS (UK) Ltd 7 Dec 1973 [8 Dec 1972 30 March 1973] 56794/72 Headings H1L and H1N A plurality of selectively operable switching elements are arranged in an array of rows and columns to form a co-ordinate switching matrix, each switching element comprising fixed contacts 102, 103, arranged to be contacted by an armature 111 centrally pivoted for movement between the contacts in response to selective energization of conductors 114, 115. A ferromagnetic yoke 116 comprising a plate 117 having pole members 118a, 118a', 118b, 118b' projecting towards the armature is arranged so that air-gaps are formed between the armature ends and these poles. Current passing in conductors 115 produces flux crossing the gaps between armature end 111a and poles 118a, 118a' in the same direction whilst current passing in conductors 114 produces flux crossing these two gaps in opposite directions, so that with selected currents the flux in one gap is cancelled and in the other is strengthened so that the armature is moved to contact one of the fixed contacts. Reversing one of the selected currents caused the armature to move to contact the other fixed contact. The arrangement is bi-stable. In an alternative embodiment, Fig. 4, (not shown), the conductors embrace the yoke and two armatures are provided which rotate in opposite directions when selected currents pass in both conductors. Sets of such armatures can be formed integrally with connecting bus-bars from a metal sheet, and the bus-bars can be supported on glass sheets 27, 28, Fig. 6, together with fixed contacts 54, 56. In this embodiment selected currents in conductors 22, 23 embracing yoke 21c, 21c', causes deflection of the armatures 25, (24) in a hollow 57 in one of the glass sheets 27 to which the armature bus-bar strips are attached. To make the device bi-stable the contacts 54, 56 on the other of the glass sheets 28 are associated with permanent magnets 29 to hold the armature on to the contact. The glass sheets are bonded around their periphery to form a sealed unit. In a still further embodiment, Fig. 8 (not shown), two yokes are associated with a single armature, one on either side of it, and the armature is attracted towards one or other of them according to the currents in the conductors embracing the yokes. The bi-stable feature in this case is provided by a bowed resilient strip on the armature, Fig. 9 (not shown).