A magnetoacoustic keyboard

A keyboard which minimizes electrical interconnections and is naturally suited for microprocessor applications has been developed using a magnetoacoustic delay line. The delay line utilizes a 2 μmeter magnetostrictive 50:50 NiFe plating on a 125 μmeter BeCu
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wire, fabricated with a circumferential easy axis. The wire is formed in a serpentine shape to pass under all the keys. The keys contain low-intensity molded permanent magnets which can rotate the magnetization from the circumferential direction. An interrogation current pulse in the wire generates acoustic waves under each depressed key, which propagate to a sense coil where the torsional waves are sequentially sensed. Each interrogation pulse from the microprocessor produces a list with the status of every key.