US 4,539,905 A · Dot matrix line printer and print element driver assembly therefor

Abstract

A dot matrix line printer incorporates plural print element driver assemblies each including N electromagnets driving N print rods, with each electromagnet having a local magnetic circuit that includes a working air gap and a passive air gap; a permanent magnet is connected to all of the local magnetic circuits. A magnetic circuit connects all of the local passive air gaps in parallel to afford a passive air gap common to all local circuits, the reluctance of the common passive air gap being of the order of 1/N times the maximum effective reluctance of the working air gap of each electromagnet. Each armature is supported by a cantilever bias spring, biasing the armature and associated print rod away from the electromagnet poles toward a print position; a stop member progressively reduces the effective length of the cantilever spring as the armature moves toward the electromagnet poles. A one-piece shuttle engages and guides the outer ends of the print rods; the shuttle includes support arms that are flexible and resilient only in a direction parallel to the dot print line and individual print rod spring guides that are flexible and resilient only in a direction parallel to the print rod axes.

Claims21

Dependent claims

An electromagnetic/permanent magnet driver assembly for a recorder, the driver assembly comprising:

N electromagnets, each electromagnet including an armature, magnetic core means affording an individual local magnetic circuit, and an electrical coil mounted on the core means for generating electromagnetic flux in the local magnetic circuit, the magnetic circuit including:
a variable working air gap with which the armature is aligned for movement between an attracted position and a released position to actuate a recording element;
and a constant local passive air gap that is separate from and independent of the working air gap;
the driver assembly further comprising:
magnetic circuit connection means interconnecting all of the individual local magnetic circuits with their individual local passive air gaps in parallel, to form a constant common passive air gap;
and a permanent magnet connected to the magnetic circuit connection means, across the common passive air gap;
the common passive air gap being connected in series with the working air gap for each electromagnet and in parallel with the working air gaps for the permanent magnet, affording an effective shunt bypassing the permanent magnet for each electromagnet.

4 more elements

In a dot matrix line printer of the kind comprising N elongated dot print rods, each having a drive end and a print end, the print ends of the print rods being aligned in spaced relation to each other along a dot print line across a recording sheet of paper or the like at a print station, and drive means including N electromagnet armatures each connected to the drive end of a print rod, the improvement comprising:

a frame;
N armature support members, each comprising a cantilever spring having a fixed end anchored to the frame and a free end supporting one of the armatures;
a shuttle member parallel to but spaced from the dot print line;
N print rod support and guide members, each comprising a cantilever spring having a fixed end anchored to the shuttle member and a free end supporting the print end of one print rod, the print rod guide members being flexible and resilient only in a direction allowing axial motion of the print rods;
and two cantilever spring shuttle support arms, each having a fixed end anchored to the frame and a free end supporting one end of the shuttle, each support arm being resilient and flexible only in a direction parallel to the dot print line.

2 more elements

Dependencies are inferred from the claim text.

Dot matrix line printer and print element driver assembly therefor

Life of this patent

Dot matrix line printer and print element driver assembly therefor

Life of this patent

Abstract

Claims21