Matrix print head and solenoid driver

A solenoid for driving a printing wire in a matrix printer comprising:

• a coil for providing magnetic flux when energized by an electrical current;
• means for providing a substantially continuous, nonrestricted path for said magnetic flux including a housing having a stationary core member enclosing one end thereof and an annular pole piece substantially closing the other end thereof and a plunger movable in one direction with respect to a central axis through said core member and pole piece;
• a first low reluctance air gap between said core member and said plunger defined by a forward conical surface of said plunger and a matching conical surface of said core member;
• a second low reluctance air gap between said pole piece and said plunger defined by an inner conical surface of a flanged rear end of said plunger and a matching outer conical surface of said pole piece;
• a printing wire fastened to said plunger extending through said core member and movable with said plunger;
• and
• means for energizing said coil such that a composite accelerating force is generated on said plunger, said composite accelerating force being generated in part by each of said air gaps.

A high speed dot matrix printing head comprising:

• housing means for containing a plurality of wires in a linear configuration;
• a plurality of solenoid drivers for propelling said wires, each of said solenoid drivers having a longitudinally reciprocally movable flanged end plunger affixed to a respective printing wire, and each of said solenoid drivers further including:
• an energizing coil;
• a substantially continuous, non-restrictive flux conductive means for providing a flux path, said flux path passing through the flanged end and a non-flanged opposite end of said movable plunger;
• and
• a first low-reluctance air gap and a second low-reluctance air gap between conical surfaces of said plunger flanged and non-flanged ends and companion conical surfaces of an associated annular pole piece and central core member of said flux conductive means for driving said plunger in response to the generation of accelerating force on said plunger by each of said first and second air gaps during energization of said coil.

A solenoid for driving a printing wire in a matrix printer comprising:

• a coil for providing magnetic flux when energized by an electrical current;
• means for providing a substantially continuous, nonrestricted path for said magnetic flux including a housing, a stationary core member closing one end of said housing, an annular pole piece spaced from said core member and substantially closing the other end of said housing, and a flanged end plunger movable normal to said pole piece and in an axial direction with respect to said core member;
• a first low reluctance air gap between said core member and said plunger;
• a second low reluctance air gap between said pole piece and said plunger, said first air gap being formed on one side thereof by a conical surface of a non-flanged end of said plunger and on the other side by a conical surface of said core member and wherein said second air gap is formed on one side thereof by another conical surface of the flanged end of said plunger and on the other side by a conical surface of said pole piece such that said air gaps have an angle with respect to said central axis of approximately 30.degree. ;
• a printing wire fastened to said plunger extending through said core member and movable with said plunger;
• means for energizing said coil such that a composite accelerating force is generated on said plunger, said composite accelerating force being generated in part by each of said air gaps;
• and
• a plunger return spring between said plunger and a spring retaining surface for maintaining said plunger in a fixed position prior to energization of said coil and for returning said plunger to said fixed position when said coil is deenergized.