GB1528158A - Pushbutton key-pad - Google Patents

Abstract

1528158 Number sending devices THORNERICSSON TELECOMMUNICATIONS (MFG) Ltd 30 July 1976 [5 June 1975] 24257/75 Addition to 1420095 Heading H4K A keypad has push buttons arranged in a plurality of rows and a set of two dimensional frames each including a code bar for each row, each button having a single centrally aligned blade which when the button is depressed engages a cam on at least one code bar causing that frame to slide in the row direction. The telephone or calculator keyboard shown is more compact, easier to assemble, cheaper and more suitable for printed circuit board mounting than the arrangement of the parent Specification. As shown four frames 110, 120, 130 and 140 are stacked on a shallow tray 16 and covered by a plastics cover 11 having lugs 15 which snap over the corners of the tray. Below each row of keys such as 1, 2 and 3 there extends a code bar on each frame and below each key each code bar has an upwardly extending lug such as 147, 127, 117 and 137, the four lugs associated with each key being positioned side by side in an order characteristic of the key. When a key is depressed a transverse blade thereon and extending over its four lugs engages cam surfaces on each lug causing each frame to slide in one direction or the other along the row guided by pins 44, 45. Each frame has a downwardly extending lug which engages switch contact springs mounted in the tray 16 and connected therethrough to terminals for connection to a printed circuit. The contact springs also function to restore the frames when the key is released. Additional lugs on the frame 140 are arranged to open and/or close auxiliary spring contact pairs depending on the exact locations in which they are inserted, when any key is depressed.