US4539905A — Dot matrix line printer and print element driver …

Claim 1

Independent Claim 185 words

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.

Claim 2

Dependent Claim 185 words

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.

Claim 3

Dependent Claim 21 words

A driver assembly according to claim 1 and further comprising armature bias means individually biasing each armature toward its released position.

Claim 4

Dependent Claim 36 words

A driver assembly according to claim 1 in which the reluctance of the common passive air gap is of the order of 1/N times the maximum reluctance of the effective working air gap for each electromagnet.

Claim 5

Dependent Claim 113 words

A driver assembly according to claim 2 in which the armature bias means comprises: N cantilever armature bias springs each supporting its associated armature on the free end of the spring; and stop means, engaging the armature bias springs, for limiting movement of each armature from its released position toward its attracted position to thereby determine the attracted position for the armature, the stop means comprising a stop member, constantly engaged by the armature bias spring, having a configuration such that it engages successive points each further displaced from the fixed end of the spring to progressively reduce the effective length of the spring as the associated armature moves toward its attracted position.

Claim 6

Dependent Claim 36 words

A drivbr assembly according to claim 4 in which the reluctance of the conmon passive air gap is of the order of 1/N times the maximum reluctance of the effective working air gap for each electromagnet.

Claim 7

Dependent Claim 131 words

A driver assembly according to claim 2 in which the magnetic core means for each electromagnet comprises first and second individual core members, each having a working gap end and a circuit connection end, with each armature spanning the two working gap ends to afford a two-part working air gap, and in which the magnetic circuit connection means comprises: a first magnetic bus connected to the circuit connection ends of all of the first core members and to one pole of the permanent magnet; and a second magnetic bus connected to the circuit connection ends of all of the second core members and to the other pole of the permanent magnet; the two magnetic buses being disposed in spaced relation to each other and defining the common passive air gap therebetween.

Claim 8

Dependent Claim 113 words

A driver assembly according to claim 6 in which the armature bias means comprises: N cantiliver armature bias springs each supporting its associated armature on the free end of the spring; and stop means, engaging the armature bias springs, for limiting movement of each armature from its released position toward its attracted position to thereby determine the attracted position for the armature, the stop means comprising a stop member, constantly engaged by the armature bias spring, having a configuration such that it engages successive points each further displaced from the fixed end of the spring to progressively reduce the effective length of the spring as the associated armature moves toward its attracted position.

Claim 9

Dependent Claim 36 words

A driver assembly according to claim 7 in which the reluctance of the common passive air gap is of the order of 1/N times the maximum reluctance of the effective working air gap for each electromagnet.

Claim 10

Dependent Claim 181 words

A driver assembly according to claim 1, for use in a dot matrix printer in which each recording element is an elongated, essentially linear print rod and the outer ends of the print rods, remote from the armatures, are aligned along a dot print line M character width spaces from each other, the driver assembly further comprising a shuttle including: two cantiliver support arms extending parallel to the print rods, with the free ends of the support arms adjacent to but spaced from the opposite ends of the dot print line, each support arm being resilient and flexible in a direction parallel to the dot print line but rigid in any direction transverse to that line; a shuttle member affixed to and interconnecting the free ends of the support arms; and N print rod guides, each comprising a cantilever spring affixed to and projecting from the shuttle member and supporting the outer end of one print rod, each guide being resilient and flexible in a direction permitting axial movement of its associated print rod but rigid in any direction transverse thereto.

Claim 11

Dependent Claim 33 words

A driver assembly according to claim 9 in which the entire shuttle, including the support arms, shuttle member, and print rod guides, is formed from a single, thin, unitary sheet of resilient metal.

Claim 12

Dependent Claim 44 words

A driver assembly according to claim 9 and further comprising a rigid frame with the electromagnets, the magnetic circuit connection means, and the permanent magnet all mounted on the frame, and with the fixed ends of the shuttle support arms affixed to the frame.

Claim 13

Dependent Claim 113 words

A driver assembly according to claim 9 in which the armature bias means comprises: N cantilever armature bias springs each supporting its associated armature on the free end of the spring; and stop means, engaging the armature bias springs, for limiting movement of each armature from its released position toward its attracted position to thereby determine the attracted position for the armature, the stop means comprising a stop member, constantly engaged by the armature bias spring, having a configuration such that it engages successive points each further displaced from the fixed end of the spring to progressively reduce the effective length of the spring as the associated armature moves toward its attracted position.

Claim 14

Dependent Claim 40 words

A driver assembly according to claim 12 in which the reluctance of the common passive air gap is of the order of 1/N times the maximum reluctance of the effective working air gap for each electromagnet, and in which M=2.

Claim 15

Dependent Claim 131 words

A driver assembly according to claim 9 in which the magnetic core means for each electromagnet comprises first and second individual core members, each having a working gap end and a circuit connection end, with each armature spanning the two working gap ends to afford a two-part working air gap and in which the magnetic circuit connection means comprises: a first magnetic bus connected to the circuit connection ends of all of the first core members and to one pole of the permanent magnet; and a second magnetic bus connected to the circuit connection ends of all of the second core members and to the other pole of the permanent magnet; the two magnetic buses being disposed in spaced relation to each other and defining the common passive air gap therebetween.

Claim 16

Dependent Claim 36 words

A driver assembly according to claim 14 in which the reluctance of the common passive air gap is of the order of 1/N times the maximum reluctance of the effective working air gap for each electromagnet.

Claim 17

Dependent Claim 213 words

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.

Claim 18

Dependent Claim 213 words

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.

Claim 19

Dependent Claim 35 words

A dot matrix line printer according to claim 16 in which the support arms, the shuttle member, and the print rod guide members are all formed from a single, thin, unitary sheet of resilient metal.

Claim 20

Dependent Claim 82 words

A dot matrix line printer according to claim 16 and further comprising: stop means, on the frame, for limiting movement of the armature toward an attracted position; the stop means comprising a stop member continuously engaged by each of the armature support members, having a configuration such that it engages successive points each further displaced from the fixed end of the support member to progressively reduce the effective length of the support member as the associated armature moves toward its attracted position.

Claim 21

Dependent Claim 35 words

A dot matrix line printer according to claim 18 in which the support arms, the shuttle member, and the Print rod guide members are all formed from a single, thin, unitary sheet of resilient metal.

Claim 22

Dependent Claim 218 words

A dot matrix line printer according to claim 16 including PN print elements and PN electromagnets arranged in P assemblies each including N print element driver electromagnets and N print elements, and in which: each electromagnet includes 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; magnetic circuit connection means interconnecting all of the individual local magnetic circuits of each assembly with their individual local passive air gaps in parallel, to form a constant common passive air gap for that assembly; and a permanent magnet connected to the magnetic circuit connection means, across the common passive air gap, in each assembly; the common passive air gap in each assembly being connected in series with the working air gap for each electromagnet in that assembly and in parallel with the working air gaps for the permanent magnet of that assembly, affording an effective shunt bypassing the permanent magnet for each electromagnet.

Claim 23

Dependent Claim 41 words

A dot matrix line printer according to claim 20 in which the reluctance of the common passive air gap in each assembly is of the order of 1/N times the maximum reluctance of the effective working air gap for each electromagnet.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1988-09-09	1989-03-11	1989-09-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1992-09-09	1993-03-11	1993-09-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1996-09-09	1997-03-11	1997-09-10	$7700.00	Window Closed / Lapsed

Dot matrix line printer and print element driver assembly therefor

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