An overview of impact printing
This paper gives an overview of impact printing and reviews some of the more recent advances made in this printing technology. Matrix and fully-formed-character impact-printing technologies are discussed for both serial printers and line printers. The critical electromechanical subassemblies that are described are the hammer unit, the paper-handling system, the inking system, and the type-element system. The mathematics describing printer performance and the operation of some of the subassemblies are presented. The relative simplicity of the impact printer still allows it to be the most economical form of text printing. Its other advantages are reliability, general insensitivity to environment, and the ability to print on the greatest variety of print media.
The contact problem in solid-ink printing
An analysis is made of the print-quality characteristics of multi-copy printing in which a rigid type font indents several layers of paper and carbon paper resting on a rigid platen. Particular attention is given to determining the contact-pressure distributions for two indenter shapes and for layers of various thicknesses. Stress distributions in the layers are computed and, using a stress-failure mechanism for solid ink, the stress distributions are found to agree well with opticalprint density and reflectance measurements obtained from experiments.
Interposer for disk printer
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.