EP0408316B1 - Schlagpunktkopf für einen Drucker - Google Patents

Schlagpunktkopf für einen Drucker Download PDF

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Publication number
EP0408316B1
EP0408316B1 EP19900307540 EP90307540A EP0408316B1 EP 0408316 B1 EP0408316 B1 EP 0408316B1 EP 19900307540 EP19900307540 EP 19900307540 EP 90307540 A EP90307540 A EP 90307540A EP 0408316 B1 EP0408316 B1 EP 0408316B1
Authority
EP
European Patent Office
Prior art keywords
armature
printing
frame
impact dot
dot head
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19900307540
Other languages
English (en)
French (fr)
Other versions
EP0408316A1 (de
Inventor
Shigeki C/O Seiko Epson Corporation Mizuno
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Seiko Epson Corp
Original Assignee
Seiko Epson Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Seiko Epson Corp filed Critical Seiko Epson Corp
Publication of EP0408316A1 publication Critical patent/EP0408316A1/de
Application granted granted Critical
Publication of EP0408316B1 publication Critical patent/EP0408316B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/22—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of impact or pressure on a printing material or impression-transfer material
    • B41J2/23—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of impact or pressure on a printing material or impression-transfer material using print wires
    • B41J2/235—Print head assemblies
    • B41J2/24—Print head assemblies serial printer type

Definitions

  • the present invention relates to an impact dot head for a printer.
  • an impact dot head for a printer comprising a frame; a plurality of printing wires which are movable within the frame into and out of a printing position; and guide means through which the printing wires pass and by means of which the printing wires are bent to different extents, each printing wire being arranged to be moved in one direction by a respective armature having a fulcrum portion engaging an engagement surface of the frame, each armature being movable in the said one direction by an electromagnetic core so as to engage an abutment surface of the latter and being arranged to be moved in the opposite direction by a respective resilient member which acts on the respective armature so as to restore the latter to an initial position, whereby each armature is subjected to a restoring force which depends both on the force exerted by the respective resilient member and by the extent to which the respective printing wire is bent, the resilient members being carried by a common support member and being substantially similar to each other but being arranged to exert different forces so that each armature
  • the object of the present invention is to provide, in an impact dot head for a printer of the kind referred to above, a construction in which there is a high degree of accuracy in the sizing of the gaps between the adjacent surface of each armature and its adjacent core so as to achieve a substantially uniform degree of magnetic attraction therebetween.
  • an impact dot head for a printer comprising a frame; a plurality of printing wires which are movable within the frame into and out of a printing position; and guide means through which the printing wires pass and by means of which the printing wires are bent to different extents, each printing wire being arranged to be moved in one direction by a respective armature having a fulcrum portion engaging an engagement surface of the frame, each armature being movable in the said one direction by an electromagnetic core so as to engage an abutment surface of the latter and being arranged to be moved in the opposite direction by a respective resilient member which acts on the respective armature so as to restore the latter to an initial position, whereby each armature is subjected to a restoring force which depends both on the force exerted by the respective resilient member and by the extent to which the respective printing wire is bent, the resilient members being carried by a common support member and being substantially similar to each other but being arranged to exert different forces so that each armature is
  • the restoring forces of the various resilient members can be varied to take account of the rotational forces exerted on the various armatures due to the bending moments of the various printing wires.
  • the total restoring force exerted on all the armatures can be made the same, so that it becomes possible to obtain uniform printing quality with a printer in which the said head is used.
  • Each of the resilient members is preferably mounted in a respective hole in the common support member, the depth of each hole depending upon the extent to which the respective printing wire is bent by the said guide means.
  • Each resilient member is preferably constituted by a coil spring.
  • the armatures are arranged in a circular or part-circular array, the ends of the printing wires remote from the armatures being arranged in at least one linear row.
  • FIG. 1 there is shown an impact printer which may be provided with an impact dot head 50 according to the present invention.
  • the impact dot head 50 is mounted on a carriage 56 for movement in the direction of the lines of print to be produced.
  • printing paper P which is arranged between a platen 57 and an ink ribbon 55.
  • FIG. 2 is a cross-sectional illustration of an impact dot head showing an embodiment of the present invention.
  • the head comprises a frame 2 which is provided with a plurality of cores 12 arranged in a circular array, a coil 17 being wound around each core 12 to form an electromagnet.
  • Two through holes 13 for each of the cores 12 are provided in the bottom surface of the frame 2, respectively, and the terminal portions 17a of the coils 17 are permanently secured, by way of an insulation plate 9, to a base plate 10 by soldering.
  • a yoke plate 3 On the upper surface of the peripheral edge of the frame 2, there are laminated a yoke plate 3, a side yoke 4, and an armature holder 5. Armatures 19, each of which faces a core 12, are arranged on a circle at equally divided intervals. An end portion of each armature 19 is fixed by brazing to an end portion of a respective printing wire 8, the.printing wires 8 being arranged on a circle at equally divided intervals.
  • each printing wire 8 which passes through a tip guide 6 which is attached to a nose 1 and through a plurality of wire guides 7, and a back guide 14, is guided thereby in such a way that a non-parallel arrangement of wires which form two vertically spaced apart linear arrays is provided at the end portions of the printing wires 8. Therefore, the amount of bending of the various printing wires 8 is different for each of the armatures 19.
  • a restoring spring holder 15 In a central hole of the frame 2 there is arranged a restoring spring holder 15 a perspective view of which is shown in Figure 3.
  • the restoring spring holder 15 is moulded from a thermoplastic resin, and a plurality of holes 15d are provided in the restoring spring holder 15. The depth H of each of the holes 15d is different and depends on its angular position.
  • a restoring spring 16 constituted by a coil spring, is mounted in each hole 15d so as to push the respective armature 19 towards a damper 20. All the restoring springs 16 are made substantially the same.
  • the restoring spring holder 15 is positioned by a positioning surface 2b of the frame 2.
  • the depth H of the hole 15d of the restoring spring holder 15 is made small at a place where the amount of bending of the respective printing wire 8 is small so as to make the restoring force produced by the respective restoring spring 16 large.
  • the restoring force produced by a printing wire 8 is large at a place where the amount of bending Y of the wire 8 is large, so that the depth H of the respective hole 15d of the restoring spring holder 15 is made large so as to make the restoring force produced by the restoring spring 16 small.
  • the calculation indicated above is carried out for each printing wire 8 to define the depth H of the respective hole 15d of the restoring spring holder 15 so as to be appropriate for each wire, in order to ensure that the restoring forces of all the armatures 19 is substantially constant and the same.
  • the range of depths H may be ⁇ 0.4 mm.
  • a plurality of slot portions 15a which are provided in the restoring spring holder 15 permit determination of the lateral position of the respective armature 19, and the armatures 19 may be moved in the direction of the slot portions 15a.
  • Three projecting portions 15b are provided on the restoring spring holder 15 and have a trapezoidal cross section, the projecting portions 15b serving as guides during insertion of the armature holder 5.
  • Two cylindrical projecting portions 15c of the restoring spring holder 15 enable determination of the positions of supporting point springs 18 which engage the armatures 19 so as to hold them in the armature holder 5.
  • a supporting point or fulcrum portion 19a of each armature 19 is caused to engage the upper or engagement surface 2a of the peripheral edge of the frame 2 by means of the respective spring 18, the latter being attached to the armature holder 5.
  • This enables each armature 19 to rotate about the supporting point portion 19a as a centre, each armature 19 being movable by the core 12 so as to engage an abutment surface 12a of the latter.
  • the engagement and positioning surfaces 2a, 2b of the frame 2 and the abutment surface 12a of the core 12 lie in a common plane.
  • Each armature 19 is retained by its restoring spring 16 in a non-operative state in which it is pushed against the damper 20.
  • a power pulse is transmitted to the respective coil 17
  • a magnetic force of attraction is generated between the respective armature 19 and the respective core 12.
  • the armature 19 is accelerated due to this force, and begins to rotate in the direction of the arrow A about the supporting point 19a as a centre.
  • the respective printing wire 8 is brought into collision with the printing paper P ( Figure 1) or other medium to form a dot.
  • the armature 19 begins to undergo a restoring action owing to the repulsion force during the collision and to the spring force of the restoring spring 16, the armature coming into collision with the damper 20 so as to complete the first printing step.
  • the amount of bending of the printing wire 8 differs for each armature 19, so that the rotational force exerted on an armature 19 by its printing wire 8 differs for each armature.
  • the depth H of the hole portion 15d in which the restoring spring 16 is located in the restoring spring holder 15 is such that the restoring force acting on the armature 19 is the same irrespective of the rotational force exerted on the armature 19 on account of the bending of the respective printing wire 8. This makes the printing force of all the printing wires 8 uniform, which makes it possible to obtain a uniform printing quality.
  • the uniform printing quality can be obtained merely by appropriate arrangement of the depths H of the hole portions 15d in which the restoring springs 16 are located in the restoring spring holder 15, so that there is no increase in the cost of the parts or in the cost of the assembly.
  • the depth of each hole 15d in which the restoring springs 16 are located in the restoring spring holder 15 changes according to the amount of bending of the respective printing wire 8, so that the restoring forces of the armatures 19 becomes uniform which makes it possible to obtain a uniform printing quality.

Landscapes

  • Impact Printers (AREA)

Claims (4)

  1. Nadeldruckkopf für einen Drucker, umfassend
    einen Rahmen (2),
    eine Mehrzahl von Druckernadeln (8), welche innerhalb des Rahmens (2) in eine und aus einer Druckstellung bewegbar sind; und
    Führungsmittel (6, 7, 14), durch welche die Druckernadeln (8) hindurchgehen, und mittels welcher die Druckernadeln (8) in verschiedenen Ausmaßen gebogen werden, wobei jede Druckernadel dazu eingerichtet ist, durch ein jeweiliges Ankerteil (19) welches einen mit einer Eingriffsoberfläche (2a) des Rahmens (2) eingreifenden Anlenkungsabschnitt (19a) aufweist, in eine Richtung bewegt zu werden, wobei jedes Ankerteil (19) durch einen elektromagnetischen Kern (12) derart in der einen Richtung bewegbar ist, daß es mit einer Gegenfläche (12a) des letzteren eingreift, und dazu eingerichtet ist, durch ein jeweiliges elastisches Element (16) in der entgegengesetzten Richtung bewegt zu werden, welches Element auf das jeweilige Ankerteil (19) derart wirkt, daß letzteres in seine Anfangsstellung zurückgeführt wird, wodurch jedes Ankerteil (19) einer Rückführkraft ausgesetzt ist, welche sowohl von der durch das jeweilige elastische Element (16) ausgeübten Kraft, als auch von dem Ausmaß, auf das die jeweilige Druckernadel (8) gebogen wird, abhängt, wobei die elastischen Elemente (16) durch ein gemeinsames Trageelement (15) getragen sind und zueinander im wesentlichen gleich sind, jedoch dazu eingerichtet sind, unterschiedliche Kräfte auszuüben, so daß jedes Ankerteil (19) im wesentlichen der gleichen Rückführkraft unterliegt, dadurch gekennzeichnet,
    daß das gemeinsame Halteelement (15) durch eine Positionieroberfläche (2b) des Rahmens (2) positioniert ist, wobei die Eingriffs- und Positionieroberflächen (2a, 2b) des Rahmens (2) und die Gegenfläche (12a) des Kerns (12) in einer gemeinsamen Ebene liegen.
  2. Nadeldruckkopf nach Anspruch 1,
    dadurch gekennzeichnet,
    daß jedes der elastischen Elemente (16) in einem jeweiligen Loch (15d) in dem gemeinsamen Trageelement (15) angebracht ist, wobei die Tiefe jedes Lochs (15d) von dem Ausmaß, auf welches die jeweilige Druckernadel (8) durch das Führungsmittel (6, 7) gebogen wird, abhängt.
  3. Nadeldruckkopf nach Anspruch 1 oder 2,
    dadurch gekennzeichnet,
    daß jedes elastische Element durch eine Spiralfeder gebildet ist.
  4. Nadeldruckkopf nach einem der vorhergehenden Ansprüche,
    dadurch gekennzeichnet,
    daß die Ankerteile (19) in einem Kreis- oder Teilkreisfeld angeordnet sind, wobei die von den Ankerteilen (19) entfernten Enden der Druckernadeln (8) in wenigstens einer geraden Reihe angeordnet sind.
EP19900307540 1989-07-13 1990-07-10 Schlagpunktkopf für einen Drucker Expired - Lifetime EP0408316B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP18074889A JPH0345352A (ja) 1989-07-13 1989-07-13 インパクトドットヘッド
JP180748/89 1989-07-13

Publications (2)

Publication Number Publication Date
EP0408316A1 EP0408316A1 (de) 1991-01-16
EP0408316B1 true EP0408316B1 (de) 1994-06-15

Family

ID=16088628

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900307540 Expired - Lifetime EP0408316B1 (de) 1989-07-13 1990-07-10 Schlagpunktkopf für einen Drucker

Country Status (3)

Country Link
EP (1) EP0408316B1 (de)
JP (1) JPH0345352A (de)
DE (1) DE69009870T2 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4843629B2 (ja) * 2008-03-14 2011-12-21 本田技研工業株式会社 車両のフロント構造

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4697939A (en) * 1982-09-17 1987-10-06 Canon Kabushiki Kaisha Wire dot printer with improved wire dot head
US4723854A (en) * 1985-05-01 1988-02-09 Brother Kogyo Kabushiki Kaisha Dot-matrix print head and apparatus for supporting pivotable armatures

Also Published As

Publication number Publication date
EP0408316A1 (de) 1991-01-16
JPH0345352A (ja) 1991-02-26
DE69009870T2 (de) 1994-09-22
DE69009870D1 (de) 1994-07-21

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