Dot printing mechanism for dot matrix line printers

Claim 1

A dot printing mechanism for dot matrix line printers comprising: (A) a carriage; (B) support means for supporting said carriage for oscillatory movement along a print line; (C) oscillation means coupled to said carriage for oscillating said carriage along said print line; and, (D) two elongate print hammer mechanisms mounted on said carriage, each of said elongate print hammer mechanisms comprising: (1) an elongate permanent magnet, said elongate permanent magnet being transversely polarized with respect to the longitudinal axis of said elongate permanent magnet such that said elongate permanent magnet has a pair of opposed polarized faces lying parallel to the longitudinal axis of said elongate permanent magnet; (2) a flux plate formed of a magnetically permeable material mounted (3) a plurality of coil posts, formed of a magnetically permeable material, mounted on the outer end of said flux plate so as to overlie said elongate permanent magnet; (4) a plurality of coils, one of said coils mounted on each of said coil posts; (5) a return plate formed of a magnetically permeable material mounted on the other polarized face of said elongate permanent magnet and extending outwardly therefrom so as to lie parallel to said flux plate, said return plate terminating short of said plurality of posts so that gaps exist there between; and, (6) a print hammer assembly mounted on the side of said return plate remote from the side mounted on said permanent magnet, said print hammer assembly including a plurality of hammer arms formed of a resilient material and a plurality of stiffeners formed of a magnetically permeable material, one of said stiffeners mounted on the end of each of said hammer arms, said plurality of hammer arms and stiffeners being equal to said plurality of posts, one of said hammer arms and stiffeners being aligned with each of said posts and extending from the area where said print hammer assembly is mounted on said return plate to the tip of said aligned post such that said stiffener lies in the gap between said return plate and said aligned post, said hammer arms and stiffeners being attracted to their aligned posts by the magnetic field produced by said permanent magnet in the absence of current through said coils, said attraction force overcoming the resilient force of said hammer arms, each of said stiffeners including a dot printing anvil located on the side of said stiffener remote from the side facing said aligned post; said two elongate print hammer mechanisms being mounted on said carriage such that said stiffeners are interleaved so that said dot printing anvils are aligned along a common print line.