GB1445971A - Magnetic key switch - Google Patents

Abstract

1445971 Saturable magnetic switches ILLINOIS TOOL WORKS Inc 15 July 1974 [15 Aug 1973] 31172/74 Heading H3X In a keyboard switch in which depression of a spring-biased key moves at least one magnet into saturating proximity with a saturable transformer, the transformer core 120, Fig. 9, and windings 122, 124 are combined with a moulded electrical insulating body 128 to form a unitary support assembly 126 releasably retained by integral wedges 176 in the switch housing. In the embodiment shown in Figs. 7 to 9 the support assembly is retained in a slot 162 in a plastics switch housing 112 by engagement of the wedges 176 with ramps 186, the wedges and ramps being disengaged to permit withdrawal of the support assembly by wedging apart the housing slot walls 127, 129. The switch is releasably retained in a panel, (not shown) by engagement of locking tabs 154 on resilient switch housing arms 152 with the panel rear surface. The key 130 is an integral part of a plunger and magnet assembly 114 comprising a pair of legs 116 supporting respective magnets 118, the legs being constrained for vertical movement only in interior spaces 138 in the housing by engagement of projections with guide channels, Fig. 5 (not shown). Biasing of the key is provided by a spring 144 located between a fixed post shoulder 149 and a recess in the key. In a modified embodiment, Fig. 10, withdrawal of the support assembly 226 permits removal of the biasing spring 244 and the plunger and magnet assembly 214 from a resilient switch housing 212. As shown the biasing spring reacts against a post 248 formed the provision of the locking wedges 229 at its ends. These wedges retain the support assembly by engaging corresponding slots in the resilient switch housing, and may be disengaged to permit withdrawal of the support assembly by distorting the housing through pressure applied to two opposite walls.