High speed printer

Claim 1

A high-speed, on-the-fly chain printer comprising: means supporting a linear font of printing characters for continuous movement in a linear path parallel to a line to be printed on a flexible print receiving medium; a linear bank of individually actuatable hammers, each hammer being operable to strike the print receiving medium against any one of said printing characters as same passes such hammer onthe-fly, there being at least fourteen of said printing characters and at least fourteen of said hammers for each linear inch of said font and said bank, respectively; including independent actuating means for operating each of said hammers; wherein said actuating means comprises a plurality of low inertia push rods each having a hammer end for engaging each of said hammers and an opposite striker end, means supporting said push rods intermediate said ends in at least one common plane for independent free axial movement in the direction of hammer striking movement, the axes of said push rods thereby being in parallel spaced interrelation, said push rods in said one common plane also being of at least three different lengths and arranged so that the hammer ends of all push rods are laterally aligned and so that the striker ends of each third push rod are in lateral alignment, and drive means to engage the striker end of each of said push rods, Said drive means being arranged in three lateral rows spaced at increments from the line of said hammer bank by a distance corresponding to the lengths of said push rods, the center to center distance between each drive means in each row being three times the spacing between push rods in said common plane; wherein said linear bank of hammers comprises interlaced upper and lower hammer tiers, the hammers in said upper tier having heads depending from a common upper pivotal axis and the hammers in said lower tier having heads upstanding from a common lower pivotal axis, the heads of said upper and lower hammer tiers being successively alternated in said linear bank so that the center to center spacing between the hammers in each tier is twice that of like spacing in said bank, said push rods also being arranged in upper and lower planar tiers to engage the respective hammers in said hammer tiers intermediate said heads and said common pivot axes, whereby the spacing of said push rods in each of said planar tiers is also twice the center to center spacing between said hammer heads in said linear bank; and comprising snubbing means for limiting striking movement of said hammers towards said printing characters, said snubbing means comprising means defining an abutment surface spaced beyond the head end of each of said hammers, each of said hammers having an abutment tang projecting beyond and presented behind said head thereby to engage said abutment surface upon actuation of said hammers; wherein said snubbing means comprises upper and lower bars each being formed having slots to receive portions of said hammers between the heads thereof and said pivotal axes respectively, said abutment surface for engagement by said tangs on said upper tier hammers being located between said slots on said lower bar and said abutment surface for engagement by said tangs on said lower tier hammers being located between said slots on said upper bar.