SE352906

1,252,768. Mechanical switches. TEXAS INSTRUMENTS Inc. 8 April, 1969 [5 April, 1968], No. 17818/69. Heading H1N. In an electric switch the operating member maintains the contacts open during its foward movement and, during its return movement, first closes and then opens the contacts. In the form shown, moving contact 5 is pivoted on the end of a flat member 3, integral with terminal 1, and co-operates with fixed contact 11 on terminal 10. Operating lever 32 projects through a slot 33 in casing 2 and is joined to a block 15, slidable in the casing 2 and carrying a spring-loaded plunger 12 which bears on the underside of moving contact 5 and, in the unoperated position (Fig. 2), holds the contacts open. Lever 32 is biased to this position by spring 24. - Block 15 has two parallel faces 17, 18, which, in the unoperated position, may slide along the inner surfaces 20, 19 of the casing 2, and also two other similar parallel faces, at an angle to the first two, which similarly form sliding surfaces when the block 15 is tilted as in Fig. 5 (not shown). When lever 32 is forwards, towards the right, block 15 initially tilts and, as it does so, a tooth 22 on the block engages over moving contact 5 so that as lever 32 and block 15 are moved towards the right, tooth 22 holds contact 5 away from contact 11. When block 15 is fully forward, tooth 22 continues to hold contact 5 away from contact 11. When lever 32 is released, spring 24 moves it in the return direction, first tilting block 15 so that faces 17, 18 again engage surfaces 20, 19 and, at the same time, moving tooth 22 away from contact 5 to free the latter and allow plunger 12 to thrust it against contact 11. During that part of the return movement between the fully operated position and the point at which plunger 12 passes beneath the pivot formed by member 3, plunger 12 maintains contact 5 against contact 11 but, when this point is passed, plunger 12 tilts contact 5 back to its initial position to open the contacts. The switch may be mounted on a washing machine door, see Figs. 9, 10 (not shown).