Abstract: A switch assembly includes an array of switches arranged on a substrate having a conductive pattern on a surface thereof defining a plurality of switch contacts. An apertured spacer is disposed adjacent the surface with an aperture being positioned in opposed relationship to each switch contact. A multi-conductive contact material is disposed to provide switch closure when forced through an aperture in the separator into engagement with a switch contact at a large number of separate conductive engagement regions. In one arrangement the multi-conductive contact material is a fine mesh woven wire screen stretched taut adjacent the separator while in another arrangement it is a uniaxially conducting material having a high density of parallel, spaced conductors extending perpendicular to the surface.

Abstract: An inexpensive, yet highly reliable, electrical switch contact assembly with excellent human factors considerations includes an electrical contact assembly having a plurality of switch positions, a cover plate disposed adjacent the switch contact assembly with an aperture for each switch position, and at each switch position an apertured key, a follower disposed within the key aperture, a cap containing the follower within the key aperture and key and follower springs biasing the key and follower respectively to provide separate and independent control over key actuation and switch contact closure forces. A contact engagement post of the follower may be accurately positioned above a switch contact notwithstanding variations in spring characteristics an a curvilinear engagement surface assures optimum distributed switch closure pressure for high reliability switch actuation.

Abstract: A keyboard switch assembly for use in telephones, calculators and the like positions a thin, flexible dielectric member with a switch closure conductive pattern printed thereon between substrate switch contacts and flexible bubble actuator mechanisms. The separate switch closure member permits the closure conductor pattern to be selected independently of constraints for proper bubble operation while permitting the flexible bubbles to be designed independently of requirements for switch closure patterns for optimum switch assembly design and operation.

Abstract: An economical yet versatile dual spring actuator switch assembly providing an excellent tactile impression includes a planar switch closure assembly having domed protrusions extending from a surface thereof to provide switch closure when depressed and a switch actuator assembly.

Abstract: A highly flexible and economical dual tone multiple frequency (DTMF) communication system includes a data input source such as a keyboard; a repertory dialer or electronic memory; an integratable digital encoder which includes a digital sine wave synthesizer; and a transmission unit such as a radio or a connection to a standard utility telephone system. The digital encoder provides a DTMF output signal at standard telephone frequencies in response to input data and includes a predial delay circuit which allows for dial tone delay or transmitter start up after receipt of data and before generation of an output signal, a two second delay circuit providing a two second output signal which may be utilized to prevent shut down between successive number entries and to lock out noise from a microphone or to a speaker and an automatic number insertion (ANI) circuit.