GB1098333A - Improvements relating to pushbutton-operated switching mechanisms - Google Patents

Abstract

1,098,333. Keysenders. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. April 5, 1966 [April 15, 1965], No. 16201/65. Heading H4K. In a V.F. keysender, the switch actuating members are arranged parallel to each other and are each pivoted about an axis transverse to the rows of push-buttons. The V.F. signals transmitted may conform to the National 2 out of 5 code. The members consist of hinged plates 4 some of which are directly operated by projections 2B depending from the buttons 2 while others are operated indirectly through the intermediary of one or more cross-bars 6 associated with each row and pivoted about axes parallel to and adjacent to the row. By removing the projections 2B or by cutting slots in the cross-bars so that they cannot be actuated by the leading edges 2C of the pushbuttons when these are depressed, various special frequency combinations can be obtained (Figs. 3A, 3B, 3C not shown). The switches actuated by members 4 may be printed circuittype wafer switches 8, plunger switches (Fig. 1B, not shown), cam-operated spring contacts (Fig. 1A, not shown), or multi-contact spring sets (Fig. 1C, not shown). The return biasing means for the members 4 may be of any conventional form. Preferably the buttons have individual restoring means which may comprise helical springs (Fig. 4A, not shown), multipoled ceramic ring magnets (Figs. 4B and 5, not shown), or a snap-action spring (30, Fig. 4C, not shown). The two latter means provide an initial restraint for the button when it is depressed so that accidental operation is minimized. The under surface of the iron stopplate, against which the ring magnet is normally retained, is provided with a thin membrane which acts as a sound-damping medium.