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US 4,493,568 AGranted
Dot matrix printhead employing moving coils
OwnerDavid A. Estabrooksinventor
Life of this patent
Estimating the term…
Abstract
Printing apparatus of the dot matrix type comprising a plurality of print wire actuators employing moving coils. The wire printing tip of each actuator is activated by the coil magnetic field interacting with an efficiently applied magnetic field substantially perpendicular to the direction of current flow in the coil. The actuator comprises a thin planar lamination having low inertia and high heat dissipation for balanced pivotal motion to provide high speed letter quality printing and high resolution graphics.
Claims26
A dot matrix electromagnetic printing apparatus movable across a paper web supported by a platen comprising:
- a plurality of elongated rectangular-shaped print wire actuators;
- a print wire connected to each of said actuators, said print wire having a printing tip portion projecting beyond a first end of said actuator;
- each of said print wire actuators including a rectangular-shaped current energizable coil for movement of said actuator in a first direction perpendicular to a corresponding magnetic field upon energization of said coil;
- a support base;
- a magnetic assembly comprising a plurality of magnetic element sets cooperating with said actuators each element set having a plurality of magnetic elements and being mounted on said support base;
- selected ones of the elements of each of said element sets being spaced from each other to provide said magnetic field in a pair of thin elongated flux gaps therebetween for containing opposing sides of the coil of at least one of said print wire actuators;
- said element sets being arranged for aligning each of said printing tip portions adjacent to one another and along at least one imaginary line;
- said printing tip impacting a print position due to movement in said first direction, and said actuator moving in a second direction to return to a non-print position;
- each of said actuators including means for supporting each of said actuators for movement of said printing tip portions in said first and second directions and for sustaining said impact at said print position;
- each of said actuators being a thin elongated, planar rectangular shaped member, said coil being flat and generally rectangular;
- said coil comprising two longitudinal coil portions, each of said coil portions arranged adjacent to the longitudinal sides of the actuator and linked by the magnetic flux path of said pole faces of opposite polarity;
- each magnetic element set comprising at least one permanent magnet and first and second pole pieces each having a first face of a large surface area engaging the pole faces of the permanent magnet, the free end faces of the pole pieces perpendicular to said first face being positioned adjacent to the longitudinal side portions of the coil and being thin and having a small surface area to concentrate the magnetic flux in said pole pieces to said thin elongated flux gaps.
9 more elements
A dot matrix electromagnetic printing apparatus movable across a paper web supported by a platen comprising:
- a plurality of print wire actuators;
- a print wire connected to each of said actuators, said print wire having a printing tip portion projecting beyond a first end of said actuator;
- a support base;
- a magnetic assembly comprising a plurality of magnetic element sets each having a plurality of magnetic elements and being mounted on said support base;
- the elements of each of said element sets being spaced from each other to provide a magnetic field in a narrow flux gap therebetween for containing at least one of said print wire actuators;
- said element sets being arranged for aligning each of said printing tip portions adjacent to one another and along at least one imaginary line;
- each of said print wire actuators including a current energizable coil for movement of said actuator in a first direction perpendicular to said corresponding magnetic field upon energization of said coil;
- said printing tip impacting a print position due to movement in said first direction, and said actuator moving in a second direction to return to a non-print position;
- means for supporting each of said actuators including each of said printing tip portions for movement in said first and second directions and for sustaining said impact at said print position;
- means in said thin flux gap for transferring heat from said coil to said magnetic element sets thereby dissipating the heat generated by said coil;
- said means comprising a liquid containing magnetic particles such that said liquid is retained in said thin flux gap by the action of said magnetic field on said particles;
- said liquid and said particles comprising said heat transfer path between said coil and said magnetic element sets.
9 more elements
An actuator for use in dot matrix printing comprising:
- a bobbinless coil surrounding an elongated hollow rectangular shaped region having two long parallel sides and two short parallel sides;
- said coil having two long sides extending along the two long sides of said hollow region and two short sides extending along the short sides of the hollow region, and being curved where the long and short side are joined;
- said coil being laminated between a pair of thin sheets of insulation material, the coefficient of thermal expansion of said insulation material substantially matching that of the coil conductive material to eliminate thermally induced mechanical stress between the coil and the laminate;
- said pair of thin sheets being laminated to one another in said hollow region;
- a print wire having a mounting end laminated between said thin sheets adjacent to one short side of said coil and a free end forming a printing tip extending away from said actuator;
- a pivot mounting laminated between said thin sheets in the hollow region surrounded by said coil and adjacent the other one of the short sides of said coil;
- a pair of spring mounting members each having a first ends electrically coupled to said coil and laminated between said thin sheets adjacent to the said other one of said short sides of the coil and extending away from said coil for electrical connection to a driving source.
4 more elements
Dependencies are inferred from the claim text.