公开(公告)号：US3591749A

公开(公告)日：1971-07-06

申请号：US3591749D

申请日：1969-05-12

Applicant: SINGER CO

Inventor： COMSTOCK JAMES MARTIN

IPC: H01H13/702 ,  H01H13/785 ,  H04M1/23 ,  H01H9/16 ,  H01H3/12

CPC classification number: H01H13/785 ,  H01H13/702 ,  H01H2201/026 ,  H01H2203/032 ,  H01H2205/006 ,  H01H2207/01 ,  H01H2207/012 ,  H01H2207/022 ,  H01H2209/014 ,  H01H2209/016 ,  H01H2217/012 ,  H01H2221/05 ,  H01H2223/034 ,  H01H2229/032 ,  H01H2229/034 ,  H04M1/23

Abstract: A printed circuit keyboard having contacts thereon with leads from the contacts passing through the board and connected to conductors on the underside of the board. A ground plane in the form of a conductive sheet is positioned above the contacts and biased out of contact therefrom. This sheet could be Mylar plated with nickel. The Mylar sheet is positioned over an apertured member aligned with the contacts to provide the biasing. The Mylar is sufficiently taut so that only one contact can be positioned against the depressed Mylar sheet at one time. A cellophane or other member can be placed over the Mylar and aligned with the apertures to provide numeric indicators for the keyboard.