Printer hammerbank with low reluctance magnetics
AssigneePrintronix, Inc.
InventorNorman E. Farb
Life of this patent
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Abstract
The specification describes a low reluctance magnetic circuit for a dot matrix line printer for retaining hammersprings by the magnetic circuit having pairs of pole pieces formed of magnetically conductive sheets having a space for receipt of a permanent magnet. A coil is wrapped around a portion of each of the pole pieces between the magnet and the ends to provide a reverse magnetic field to the magnetic field provided by the permanent magnet. A magnetic shunt is established between the pole pieces to provide a greater magnetic effect. The pole pieces are sized and plated at the ends, with a spaced wear bar between them to provide improved performance and longer wear.
Claims27
A low reluctance magnetic circuit for a dot matrix line printer for retaining hammersprings by said magnetic circuit comprising:
- a pair of pole pieces formed of a magnetically conductive metal with ends proximate the hammersprings, having a space between them with a permanent magnet emplaced in said space;
- a coil wrapped around a portion of each of said pole pieces between the magnet and said ends thereof to provide a reverse magnetic field to the magnetic field provided by said permanent magnet through said pole pieces;
- and,
- a metallic magnetic shunt between said pole pieces.
A dot matrix printer having a hammerbank which reciprocates to provide printed dots against a piece of paper on a platen wherein the improvement comprises:
- a hammerbank having a plurality of hammersprings mounted thereon adapted for magnetic retention;
- pairs of pole pieces respectively having ends in proximate relationship to said hammersprings to provide magnetic retention to the ends of said hammersprings and having a space removed from said hammersprings with a permanent magnet emplaced in said space;
- and,
- a metallic shunt between said pole pieces for providing a magnetic shunt with respect to said permanent magnet.
A plurality of pairs of magnetically conductive pole pieces in combination with a hammerspring on a hammerbank for a line printer wherein said hammerspring is connected to said hammerbank at one end and provided with a tip distal therefrom for printing against a print ribbon for printing on paper wherein the improvement comprises:
- pairs of pole pieces providing a magnetic circuit having a space between the pair proximate one end with a permanent magnet emplaced therein, and ends distal therefrom for providing a magnetic retention force to said hammerspring;
- and,
- a metallic shunt between said pole pieces.
The combination as claimed in 20 further comprising;
- an impact bar emplaced between the ends of said pole pieces for said hammerspring to impact thereagainst.
Dependencies are inferred from the claim text.