Typewriter letter hammer group with magnetic shunt

Abstract

An impact line printer comprising a print ribbon wound on a pair of spools for traversal in two directions across a plurality of print hammers having tips for impacting the print ribbon to print on a media. A permanent magnet having two pole pieces having pole piece ends in adjacent relationship to the print hammers retains the print hammers until a coil in associated relationship with each pole piece releases the magnetic retention of the hammers. A magnetically permeable extension is longitudinally adjacent each hammer which acts as a magnetic shunt to permit more rapid printing rates and higher impacts. The extensions conduct and shunt magnetic flux from the hammers through the longitudinally adjacent extensions.

Description

technical field

[0001] The present invention relates to the technical field of impact printing. Impact printing can be done by having a protruding hammer whose tip strikes the ribbon to form a series of dots or dot pattern on the underlying media. The present invention more particularly relates directly to a line printer hammerset having a series of hammers held by permanent magnets and released for striking by an electric coil overcoming the permanent magnets. Background technique

[0002] The prior art relating to impact printers generally presents impact printers of many different designs and configurations. One of the preferred types of impact printers are those known as line matrix printers. A line matrix printer is constructed in which a hammer set having a plurality of printing tips strikes a printing ribbon covering the medium to be printed on. The hammer is controlled and held by a permanent magnet until released for striking. In order to hold the hammer, the pe...

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