GB1038655A - Electric switch - Google Patents

Abstract

1,038,655. Retractive switches; contactmembers for switches. ROBERTSHAW CONTROLS CO. May 1, 1964 [May 2, 1963], No. 18269/64. Heading H2B. Contact bounce in a switch suitable for computers or electric typewriters, for example, is prevented by the provision of a two-pronged resilient member 20 overlying one of the contacts such that it is engaged prior to the contacts making, the two prongs 22 and 24 (Fig. 2, not shown) being of different widths or masses to have different resonant frequencies. The member 20 may be made of spring silver sheet material 0À004 inch thick, with gold plating. In the switch shown, a plunger 90 moves a resilient arm 78 to cause an over-centre C-spring 72 to change-over the contact-carrying blade 60 with a snap action. Blade 60, arm 78, and fixedcontact supports 34 and 36 are tightly held in recesses between upstanding formations 40, 42 and 44 and a cover (Fig. 13, not shown) is located on ledges 31B, 30B and 33B, and retained by screws engaged in holes 98. A pair of ears 91 are provided with holes 89 to pivot an actuating lever (not shown). An antibounce prong member may be provided on each fixed contact (Fig. 5, not shown), or alternatively the prong members may be carried on the moving contacts (Fig. 6, not shown).