| 摘要 |
1,255,761. Electric couplings. CONTROL DATA CORP. 26 Jan., 1970 [11 Feb., 1969], No. 3688/70. Heading H2E. [Also in Division B6] A keyboard comprises conductive pads 16, a common bus member 12, and a conductive sheet 22 laid over the pads 16 and member 12, a connection between a selected pad 16 and the bus member 12 being formed by applying pressure to the pad whereby the electrical resistivity of a pad 20 of a pressure-sensitive material is reduced. The pressure sensitive material may be a pressure-sensitive paint, carbon-impregnated rubber, fibres impregnated with conducting particles, foamed material impregnated with conductive material or finely divided or granulated carbon, and has a resistivity varying inversely with the applied pressure. An insulating layer 24 and character indicating symbols 26 may be superposed on the conductive sheet 22. The keyboard may be manufactured by a method comprising the steps of: bonding an electrically conductive surface to an insulating base member, selectively etching away the conductive surface to form a pattern (Fig. 4, not shown) of conductive pads and paths, filling the cavities formed by the etching step with insulating material such as epoxy resin, partially etching the pads and some of the paths, filling the resulting cavities above pads with pressure sensitive material having an electrical resistivity inversely proportional to an applied pressure, filling the cavities above partially etched paths with insulating material, and overlaying a conductive sheet over the pressure sensitive and insulating materials to form an electrical connection between the pressuresensitive material and conductive paths which were not etched. |
