Impact printer hammer assembly
AssigneePlessey Peripheral Systems
InventorJohn R. Veale
Life of this patent
Estimating the term…
Abstract
In a solenoid driven hammer for an impact printer, the armature, which is driven by the magnetic field provided by the solenoid's coil, is integral with the hammer which strikes a printing element on a print wheel. The shape of the pole piece in the solenoid conforms to the shape of the leading surface of the armature to provide a magnetic force field that is of constant strength as the armature is propelled toward the pole piece when the solenoid coil is energized. The hammer, being unitary with the armature, is thereby propelled against the printing element. As the hammer rebounds after striking the printing element, the armature strikes a polyurethane cushion which absorbs substantially all of the energy of the armature/hammer unit, thereby bringing the unit to a complete stop so that the next stroke may be quickly commenced.
Claims10
A hammer assembly for a high speed impact printer, comprising:
- a solenoid having a coil and an axially apertured pole piece, said pole piece having a conically shaped recessed surface;
- an axially movable armature within said solenoid, said armature having a tapered conical leading surface substantially parallel to the recessed surface of said pole piece, said parallel conical surfaces producing a constant magnetic field characterized by parallel lines of force of uniform density, said coil being energized by a constant current whereby the constancy of said magnetic field is enhanced, said armature being propelled toward said pole piece by the magnetic attraction of said constant field when said coil is energized by said constant current;
- and
- hammer means rigidly connected to said armature to form a unitized armature/hammer element, for striking a print element in said printer, said hammer means being uniformly accelerated due to said constant field and axially moved a substantially long distance through said pole piece armature by the movement of said armature.
A hammer assembly for a high speed impact printer;
- comprising:
- a solenoid having a coil and a pole piece, said pole piece having a conically-recessed surface;
- an armature in said solenoid having a conical surface facing and substantially parallel to said conical pole piece surface, said armature being propelled toward said pole piece by magnetic attraction when said coil is energized by a constant current;
- hammer means, rigidly connected to said armature, for striking a print element in said printer when said armature is propelled toward said pole piece;
- and
- said parallel conical surfaces on said armature and said pole piece and said constant current producing a magnetic force of substantially constant magnetic between said pole piece and said armature as said armature moves toward said pole piece, so that said armature and said hammer means move with a substantially constant acceleration through a substantially long distance.
A hammer assembly for a high speed impact printer, comprising:
- first means for producing a magnetic field;
- second means for striking a print element in said printer;
- and
- third means responsive to said magnetic field, for both (a) driving said second means toward said print element with substantially constant acceleration, and (b) controllably decelerating said second means as it rebounds after striking said print element.
Dependencies are inferred from the claim text.