Printronix, Inc.

John W Gemmell

Rudy Concepcion, Jr

Rohit Sharma

Gordon B Barrus

Dennis R White

Lihu Chiu

Kevin P Moore

Y Grant Chang

John Stanley Kinley

Jeng-dung Jou

In one embodiment, a hammer bank for a line printer includes a back plate having a front surface, a back surface and a uniform thickness between the front and back surfaces. At least one hammer is disposed in front of the back plate. The at least one hammer is spring-biased for forward movement and away from the back plate and is releasably retained against such forward movement by a magnetic force acting rearwardly thereon. An elongated pole piece that is associated with the at least one hammer extends forwardly from the front surface of the back plate and is selectively operable to interrupt the magnetic force acting thereon.

Line printer hammer banks

In one embodiment, a hammer bank for a line printer includes a back plate and a plurality of elongated pole pieces extending forwardly from a front surface thereof. Each of the pole pieces has an electrical coil disposed about a circumfery thereof. A permanent magnet has a back surface coupled to the front surface of the back plate, and a shunt fret defining a plurality of elongated, downwardly extending shunts has a back surface coupled to a font surface of the permanent magnet. A hammer fret defining a plurality of elongated, upwardly extending hammers has a back surface coupled to the front surface of the back plate. Each of the hammers is interdigitated between a pair of adjacent shunts. Each hammer includes an elongated spring portion having a hammer head disposed at an upper end thereof, and each hammer head has a forwardly projecting printing tip thereon.

An ink density closed loop control system for an ink ribbon of an impact printer having a reservoir roller formed of an ink absorbent material with at least one or more channels within the reservoir roller fluidly connected to a pump and ink supply. A transfer roller can contact the reservoir roller for imparting ink to the ink ribbon. A sensor senses the relative amount of ink on the print ribbon and an electrical drive responsive to the sensor drives the pump for a flow of ink to the one or more channels. The sensor can sense ink on different segments of the ribbon and, with two or more channels in the reservoir roller can distribute ink to two or more segments of the reservoir roller depending upon the ink sensed at a particular segment of the ribbon. A further enhancement of this invention provides a multi-viscosity ink to compensate for changes in ambient temperature conditions.

Constant density printer system

An impact printer with a hammerbank having print hammers retained by a permanent magnet for impacting a print ribbon, and a mechanical driver for moving the hammerbank across print media. First and second coils for each hammer are wrapped around first and second pole pieces, one of which is asymmetrical to the other pole piece. One of the pole pieces can have a generally elongated longitudinal form with the coil wound around the longitudinal form and the other can have a generally arcuate form, with the coil wrapped on a portion between the ends thereof. The coil wrapped around the arcuately formed pole piece is thicker than the coil wrapped around the longitudinal pole piece. The result is to provide pole pieces and coils for an impact printer having differing spatial relationships that can be staggered, or formed asymmetrically for more compact coil and pole piece placement to improve printer efficiency.

Line printer with staggered magnetics

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.

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Aliso Viejo, CA, United States of America

John W Gemmell