EP0269959B1 - Tête d'impression de type à fils - Google Patents

Tête d'impression de type à fils Download PDF

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Publication number
EP0269959B1
EP0269959B1 EP19870117115 EP87117115A EP0269959B1 EP 0269959 B1 EP0269959 B1 EP 0269959B1 EP 19870117115 EP19870117115 EP 19870117115 EP 87117115 A EP87117115 A EP 87117115A EP 0269959 B1 EP0269959 B1 EP 0269959B1
Authority
EP
European Patent Office
Prior art keywords
armature
core
permanent magnet
coil
wire
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
Application number
EP19870117115
Other languages
German (de)
English (en)
Other versions
EP0269959A1 (fr
Inventor
Tatsuya Koyama
Tetsuhiro Yamada
Hirokazu Andou
Katsuya Kamimura
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.)
Oki Electric Industry Co Ltd
Original Assignee
Oki Electric Industry Co Ltd
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
Priority claimed from JP61179816A external-priority patent/JPS6231717A/ja
Application filed by Oki Electric Industry Co Ltd filed Critical Oki Electric Industry Co Ltd
Publication of EP0269959A1 publication Critical patent/EP0269959A1/fr
Application granted granted Critical
Publication of EP0269959B1 publication Critical patent/EP0269959B1/fr
Expired 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
    • B41J2/27—Actuators for print wires
    • B41J2/28—Actuators for print wires of spring charge type, i.e. with mechanical power under electro-magnetic control

Definitions

  • the present invention relates to wire-type printing heads used in serial printers and operating on a principle of energy of deformation accumulated in a leaf spring under the effect of the magnetic energy of a permanent magnet with subsequent conversion of the above-mentioned energy of deformation into the energy of printing due to the electric current which is passed, in accordance with a data to be printed, through a coil to create an electromagnetic force cancelling the attractive force of the permanent magnet.
  • Fig. 1 is a semi-sectional view of a known spring-loaded wire-type printing head
  • Fig. 2 is a sectional view along line A-A of Fig. 1.
  • reference numeral 1 designates a disk-shaped rear yoke. Stacked on the peripheral surface of rear yoke 1 are a permanent magnet 2, an intermediate yoke 3, and an armature 4. One end of a leaf spring 5 is rigidly clamped between armature yoke 4 and intermediate yoke 3. The leaf spring 5 extends radially inward, i.e., toward the center of the disk-shaped rear yoke 1.
  • leaf spring 5 Fixed to the free end of leaf spring 5 is an armature 6 which carries on its free end the base (rear end) of a printing wire 7 which is rigidly attached thereto.
  • the tip (front end) of printing wire 7 is arranged so that it can project through a guide portion 8a of a wire guide 8.
  • a core 9 Located in the central portion of rear yoke 1 is a core 9 which is surrounded by a coil 10.
  • Reference numeral 11 designates a center pole which forms a magnetic path for a magnetic flux generated by coil 10.
  • Reference numeral 12 designates a magnetic path formed by permanent magnet 2.
  • the demagnetization flux of coil 10 creates interferences by flowing through paths 14a, 14b formed by adjacent armatures 611, 6111 and cores 911 and 9111 (Fig. 2).
  • the known wire-type printing heads have an inefficient path for the demagnetization flux developed by the coil, and until now the problem of magnetic interference in these devices has not yet been solved.
  • auxiliary core which forms an independent magnetic flux by means of a coil installed between the permanent magnet and the core.
  • the end of the above-mentioned auxiliary core serves as a fulcrum point for the armature.
  • the magnetic flux developed by the coil flows through the core in the direction opposite to that of the magnetic flux developed by the permanent magnet, passes through the armature, enters the auxiliary core, and thereby can efficiently suppress the magnetic flux of the permanent magnet.
  • the permanent magnet flux which enters the auxiliary core exerts almost no effect on the force of magnetic attraction developed by the armature.
  • the magnetic fluxes of the coils penetrate, to a lesser extent, into the adjacent armatures and cores, and the total magnetic interferences are reduced.
  • Fig. 3 is a sectional view illustrating a wire printing head made in accordance with the first embodiment of the invention.
  • Fig. 4B is a perspective view of cores, coils and auxiliary cores of the same wire printing head.
  • Fig. 4A is a perspective view of armatures and leaf springs positioned above the cores, coils and auxiliary cores.
  • the device comprises a rear yoke 1 which carries an auxiliary core 14, a core 9, and a center pole 11, all these parts being arranged sequentially in the stated order toward the center, with their ends facing an armature 6.
  • auxiliary core 14 forms a separate path 16 for a magnetic flux developed by a coil 10.
  • Core 14 is made of the same ferromagnetic material as core 9.
  • Core 14 is disposed to form a predetermined gap between it and the core 9, on the side of the core 9 facing the permanent magnet 2.
  • auxiliary core 14 The forward (top as seen in the figure) end of auxiliary core 14 is used as a fulcrum point for swinging motions of armature 6.
  • the above-mentioned armature has a cross section sufficient for magnetic paths.
  • the magnetic paths include magnetic path 12a of the flux generated by permanent magnet 2 and magnetic paths 16 and 17 of the fluxes generated by coil 10. Among these, magnetic path 16 passes through auxiliary core 14, and magnetic path 17 passes through central pole 11.
  • the above-mentioned armature 6 and opposite parts 18 of downward protrusions 4a of armature yoke 4 that are adjacent to the side surfaces of armature 6 are located near or above core 9, or they can be arranged so that a distance between auxiliary core 14 and permanent magnet 2 is substantially greater than the gap between core 9 and auxiliary core 14.
  • Reference numeral 3 designates an intermediate yoke
  • 5 is a leaf spring
  • 7 is a printing wire.
  • the proposed wire-type printing head operates as follows:
  • the force of attraction of armature 6 is due to a torque for rotation of armature 6 on the fulcrum point formed by the top portion 14a of auxiliary core 14. Moreover, almost all the entire torque is developed by core 9. The portion of the magnetic flux which flows through auxiliary core 14 and is developed by permanent magnet 2 exerts almost no influence on the force of attraction of armature 6.
  • coil 10 When, on the other hand, coil 10 is energized, the flux induced by coil 10 flows in the direction opposite to that of the flux induced by permanent magnet 2, passes through armature 6, flow through auxiliary core 14, and at the same time enters central pole 11.
  • Figs. 5 and 6 show experimental data. More particularly, Fig. 5 is a graph which illustrates a relationship between peak currents of the coil and the number of simultaneously operating wires. Fig. 6 is a graph showing the relationship between the number of simultaneously operating wires and the energy supplied to the coil.
  • the ratio of an increase in the current in the case of twelve simultaneously operating wires, as compared to one wire corresponds to the following:
  • Fig. 7 is a sectional view of a wire-type printing head corresponding to the second embodiment of the proposed device.
  • the device of the second embodiment is similar to that of the first embodiment, except that is does not have a central pole.
  • the auxiliary core and the main core are made from the same material. It is obvious, however, that these parts can be made from different materials, provided that both these materials have ferromagnetic characteristics.
  • the main core can be made from Permendur, or a similar material with properties of high magnetic saturation, while the auxiliary core is produced from silicon steel.
  • the auxiliary cores 14 extend separately from the rear yoke 1. But, alternatively, lower parts of the auxiliary cores 14 may be connected by bridging members 19, as shown in Fig. 8.
  • the bridging members 19 can be of the same magnetic material as the auxiliary cores 14 and can be formed integrally with them.
  • the proposed device contains an auxiliary core which is located on the side of the permanent magnet of the core and forms a separate magnetic path for a flux developed by the coil, and because the top end of this auxiliary core serves as a fulcrum point for rock movements of the armature, the flux developed by the coil can more efficiently flow through the auxiliary core.
  • An additional effect is that the coil does not generate heat, and printing can be performed in a high-duty mode.

Landscapes

  • Impact Printers (AREA)

Claims (3)

1. Tête d'impression du type à aiguilles comportant
une aiguille d'impression (7) s'étendant vers l'avant,
une armature (6) à laquelle une extrémité arrière de l'aiguille (7) est fixée,
un noyau (9) ayant son extrémité avant adjacente à une surface arrière de l'armature (6),
un bobinage (10) enroulé sur le noyau (9),
un aimant permanent (2),
un ressort à lame (5) ayant une première extrémité fixée à proximité de l'aimant permanent (2) et une deuxième extrémité fixée à l'armature (6),
des moyens (1, 4) destinés à compléter un passage magnétique fermé pour le flux magnétique provenant de l'aimant permanent (2), en passant par le noyau et l'armature,
des moyens destinés à amener un courant électrique à-s'écouler au travers du bobinage (10) afin de générer un flux magnétique au travers du noyau (9) dans une direction de façon à annuler le flux magnétique dû à l'aimant permanent (2),
l'armature (6) étant attirée vers le noyau de façon à déformer élastiquement le ressort à lame (5) lorsque le bobinage (10) n'est pas excité, et
l'armature (6) étant relâchée et déplacée vers l'avant sous l'action du ressort à lame (5) lorsque le bobinage (10) est excité, caractérisée par
un noyau auxiliaire (14) positionné entre l'aimant permanent (2) et le noyau (9) et ayant une extrémité avant adjacente à la surface arrière de l'armature (6),
des moyens destinés à compléter un passage magnétique fermé pour le flux magnétique provenant du noyau (9) en passant par l'armature (6) et le noyau auxiliaire (14),
la surface arrière de l'armature (6) étant maintenue en contact avec l'extrémité avant du noyau auxiliaire (14) de telle sorte que l'extrémité avant du noyau auxiliaire (14) constitué un point d'articulation pour le basculement de l'armature (6).
2. Tête d'impression selon la revendication 1, caractérisée en ce que les moyens destinés à compléter le passage magnétique fermé pour le flux magnétique comporte un bloc arrière (1) reliant l'aimant permanent (2) et le noyau (9) et un bloc d'armature (4) ayant une extrémité adjacente à la surface avant de l'armature (6) et ayant une autre extrémité reliée magnétiquement à l'aimant permanent (2).
3. Tête d'impression selon la revendication 1, caractérisée en ce que le noyau auxiliaire (14) s'étend en avant du bloc arrière (1).
EP19870117115 1986-07-30 1987-11-19 Tête d'impression de type à fils Expired EP0269959B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP61179816A JPS6231717A (ja) 1985-07-31 1986-07-30 ロ−ル
JP179816/86 1986-11-25

Publications (2)

Publication Number Publication Date
EP0269959A1 EP0269959A1 (fr) 1988-06-08
EP0269959B1 true EP0269959B1 (fr) 1991-01-23

Family

ID=16072389

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870117115 Expired EP0269959B1 (fr) 1986-07-30 1987-11-19 Tête d'impression de type à fils

Country Status (1)

Country Link
EP (1) EP0269959B1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE68906840T2 (de) * 1988-09-13 1993-10-14 Seiko Epson Corp Anschlagpunktdrucker.

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5749576A (en) * 1980-09-11 1982-03-23 Nec Corp Printing head of dot matrix printer
JPS59150755A (ja) * 1983-02-18 1984-08-29 Oki Electric Ind Co Ltd ドツトインパクト印字ヘツド
JPH042055Y2 (fr) * 1985-01-16 1992-01-23

Also Published As

Publication number Publication date
EP0269959A1 (fr) 1988-06-08

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