In an impact printer which selects characters by having a hammer hit type elements as they travel at constant velocity past the print location, a significant design problem results from the requirement that the hammer hit only the selected character. In the usual configuration this requirement limits printing speed because the hammer penetrates the plane of the moving type elements and spends a sufficient time in this plane to risk collision with an adjacent type element. This paper describes, for printers with widely separated hammers, a technique to effectively eliminate the “in-plane” time. A cammed interposer is used to transfer most of the kinetic energy of the hammer to the type element, with the remaining energy being absorbed in strain energy of the interposer. For one printer, this technique resulted in an increase in the printing speed from 15 to 30 characters per second.
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