EP0041126A2 - Mosaikdruckkopf mit Mitteln zur Verhinderung des Übersprechens - Google Patents
Mosaikdruckkopf mit Mitteln zur Verhinderung des Übersprechens Download PDFInfo
- Publication number
- EP0041126A2 EP0041126A2 EP81103083A EP81103083A EP0041126A2 EP 0041126 A2 EP0041126 A2 EP 0041126A2 EP 81103083 A EP81103083 A EP 81103083A EP 81103083 A EP81103083 A EP 81103083A EP 0041126 A2 EP0041126 A2 EP 0041126A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- magnetic
- armature
- printing head
- pole piece
- shields
- 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.)
- Granted
Links
Images
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
- B41J2/275—Actuators for print wires of clapper type
Definitions
- the present invention relates to a mosaic printing head with cross-talk preventing.means in the electromagnetic structures of the printing head, the cross-talk limiting the printing speed.
- a mosaic printing head generally comprises a needle guide assembly and a plurality of electromagnetic structures coupled to the guide as sembly.
- the electromagnetic structures are mounted on an electromagnetic support and each structure includes a magnetic circuit formed by two po le pieces connected by a yoke and by a movable armature which comple tes the magnetic circuit. It further includes at least a coil wound around one of the two pole pieces.
- each of the electromagnetic structures acts as an activator for one of the printing needles.
- each movable armature is provided with at least an arm which protudes externally to the electro magnetic structure and operates as an actuating arm for the associated needle.
- the electromagnetic structures are radially arranged on the electromagnetic support preferably constituted by a ring member.
- One of the two pole pieces of each magnetic circuit is arranged proximate to the internal periphery of the support ring, whilst the other is arranged in proximity to the external periphery of it (from now on the pole pieces will be named internal or external pole piece).
- the radial arrangement of the magnetic circuits involves that the internal pole pieces are closer together than the external pole pieces.
- the internal pole piece is generally that one which attracts the free end of the armature: therefore an air gap exists at rest between such pole piece and the armature.
- the magnetic field produced in the magnetic circuit has a leakage in correspondence of the initially open air gap: the more the ratio between the open air gap length and the adjacent pole piece distance increases, the more the flux lines tend to link with adjacent internal pole pieces.
- the armature of the excited electromagnet is attracted as soon as the attraction force exerted on it by the magnetic field exceedes the va lue of the resisting force produced by a spring which determines at rest the opening of the magnetic circuit.
- the attraction force on the movable armature is directly proportio nal to the value of the magnetic energy in the air gap, owing to the stealing of magnetic energy in the air gap from the adjacent magnetic circuits, the armature of the excited magnetic circuit is attracted with a certain delay compared with the ideal case when there is no leakage or stolen flux.
- the actuation time of a printing needle changes according to whether the elec tromagnets near to the one associated to the needle are excited or not.
- This problem limits the printing speed of the head as the upper limit of such speed is imposed by the maximum flying time of the needles. Besides that it causes misalignment in the printing operations due to the fact that such operations do not occur in steady printing head conditions but when the head is moving along the printing line.
- a solution to reduce the above mentioned inconvenients could be the one of increasing the diameter of the circular support of the electro magnetic structures, so that the open air gap width is much lesser than the distance between the internal pole pieces of two adjacentma gnetic circuits.
- a solution used for line printers involves the use. of magnetic shields for the actuator elec tromagnets of the printing hammers, in order to avoid differences in hammer flying time.
- Magnetic shields could be used for mosaic printing heads to, but such solution would however involve leakage fluxes and performance degradation.
- cross-talk prevention means of the present invention which provide a "dynamic" shielding against the leakage fluxes instead of the static shielding achievable by means of the magnetic shields.
- the critical portion of the magnetic circuit in a matrix printing head is, as already mentioned, the pole piece arranged in proximity to the internal periphery of the electromagnetic support, because of the air gap existing at rest between such pole piece and the armature. If such pole piece is shielded by conductive material, the magnetic flux of the magnetic circuit including such pole piece is prevented from linking to the internal pole pieces of the adjacent magnetic cir cuits. Therefore the conductor material shield confines the flux with in the appropriate magnetic circuit.
- variable magnetic flux tending to cross the metallic shield during the electromagnet initial excitation phase induces eddy .currents within it.
- Such eddy currents generate a magnetic field opposing the inducing one.
- the induced magnetic field causes a flux concentration inside the air gap and a leakage flux reduction.
- fig. 1 shows in side view an example of mosaic prin ting head structure.
- the printing head of fig. 1 comprises a needle guide assembly 2 and an electromagnetic assembly 3.
- the needle guide assembly comprises a frame 4 having a bracket 6, fixed to the frame by a screw 5, which supports a guide for the printing ends of the needles generally formed by a pair of suitably-shaped ruby plates 7.
- the needle guide assembly 2 is fixed to electromagnetic assembly 3by means of two screws (in fig. 1 the head 8 of one of such screws is visible) which lock two brackets formed on the sides of frame 4 against the electromagnetic assembly 3 (in fig. 1 one of such two brackets, evidenced by 9, is visible).
- the electromagnetic assembly 3 comprises a supporting disk 10, to which a suitable number of electromagnets, such as 12, 13, 14, ...18, are fixed, an internal bushing (11, Fig. 2) fixed by calking or shrin kage in a central opening of disk 10 (in alternative the bushing and the disk may form a unitary, sintered, casted, or molded body), an ar mature retainer 19 and a central cap 20.
- the armature retainer 19 is fixed to the bushing (reference 11 in fig. 2) by means of the central cap 20.
- Central cap is provided in proximity of its external periphery with openings, each one receiving a screw (in fig. 1 only two screws21, 22 are visible).
- Such screws insert into corresponding openings present in the armatu re retainer 19 and engage in corresponding threaded holes (references 23, 24, 25 in fig. 2) of the bushing.
- fig. 1 also shows that the external sur face of the ruby plates 7 is placed at a certain distance from a pla ten 26 of the printer.
- a paper printing support 27 and an inked ribbon-28 are interposed bet ween platen 26 and ruby plates 7.
- Fig. 2 shows in exploded view some of the elements forming the electromagnetic assembly 3.
- the supporting disk 10 in form of annular element having a central opening where the bushing 11 is engaged, has a suitable number of rec tangular openings (in fig. 2 nine openings 29, 30, ....37 are visible) intended to restrain an extension which each magnetic circuit is pro vided with.
- These openings are radially arranged around the disk center and uniformly distributed near the disk periphery.
- Electromagnet 38 comprises a magnetic core 39 formed by a pack of U shaped magnetic sheets provided in correspondence of the yoke with an extension 40 for insertion in one of the rectangular openings'of disk 10, for instance opening 30.
- a coil 41 is wound around one of the two pole pieces of the core 39, and precisely around the one arranged in proximity of the external periphery of disk 10 (the external pole piece).
- the internal pole piece of the magnetic core 39 is partially surroun ded by a conductive, non magnetic shield 42 (for instance copper) having C cross section.
- the electromagnet 38 is completed by a movable armature 43 closingthe magnetic circuit.
- the armature 43 has an extended arm 44 which acts as an activator arm on the head 45 of a needle 46 associated to such armature.
- the magnetic circuit formed by core 39 and armature 43 has an air gap in correspondence of the internal pole piece, owing to the action of a spring 47 on arm 44 of armature 43 through head 45.
- the armature retainer 19 (fig. 1) keeps the armature 43 in contact with the external pole piece of magnetic core 39.
- the characteristic object of the present invention is the conductive non magnetic shield 42 which partially surrounds the internal pole piece of the magnetic core 39.
- shield 42 does not cover the pole piece face leaning against bushing 11: the shielding effect on such face may be carried out by the same bushing, which can be made in aluminium.
- the shield 42 must not be in contact with bushing 11, if such last is of conductor material.
- the open turn or C section of shield 42 is essential to avoid that such shield be linked with the main path of the magnetic flux, as it would occur in case of a closed ring.
- the conductive non magnetic shields of the magnetic circuits in the electromagnetic structures of a mosaic printing head may clearly have shapes other than the described one, without departing from the scope of the invention.
Landscapes
- Impact Printers (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT2181580 | 1980-05-06 | ||
IT21815/80A IT1131146B (it) | 1980-05-06 | 1980-05-06 | Mezzi di riduzione della diafonia in una testina stampante a mosaico |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0041126A2 true EP0041126A2 (de) | 1981-12-09 |
EP0041126A3 EP0041126A3 (en) | 1982-07-14 |
EP0041126B1 EP0041126B1 (de) | 1984-12-05 |
Family
ID=11187238
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP81103083A Expired EP0041126B1 (de) | 1980-05-06 | 1981-04-24 | Mosaikdruckkopf mit Mitteln zur Verhinderung des Übersprechens |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0041126B1 (de) |
DE (1) | DE3167553D1 (de) |
IT (1) | IT1131146B (de) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4929101A (en) * | 1988-05-27 | 1990-05-29 | Tokyo Electric Company, Ltd. | Release-type dot print head |
EP0385047A1 (de) * | 1989-03-01 | 1990-09-05 | MANNESMANN Aktiengesellschaft | Matrixdruckkopf mit einem Elektromagnetspulenträger |
US4976554A (en) * | 1987-10-15 | 1990-12-11 | Tokyo Electric Company, Ltd. | Release-type dot print head and method of manufacturing the same |
US5011308A (en) * | 1988-05-10 | 1991-04-30 | Tokyo Electric Co., Ltd. | Releasing type dot printer head |
DE4338655A1 (de) * | 1993-03-17 | 1994-09-22 | Fujitsu Ltd | Magnetgrundkörper für Druckkopf von Nadeldrucker und Verfahren zum Herstellen desselben |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN114953738B (zh) * | 2022-05-20 | 2023-05-23 | 合肥领迅喷码科技有限公司 | 一种喷码机 |
-
1980
- 1980-05-06 IT IT21815/80A patent/IT1131146B/it active
-
1981
- 1981-04-24 EP EP81103083A patent/EP0041126B1/de not_active Expired
- 1981-04-24 DE DE8181103083T patent/DE3167553D1/de not_active Expired
Non-Patent Citations (2)
Title |
---|
"Handbuch für Hochfrequenz- und Elektrotechniker" von C. Rint, Verlag für Radio-Foto-Kinotechnik GmbH, Berlin-Borsigwalde, Vol. 1, pages 406 and 407, edition 1965 * |
No documents have been disclosed. * |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4976554A (en) * | 1987-10-15 | 1990-12-11 | Tokyo Electric Company, Ltd. | Release-type dot print head and method of manufacturing the same |
US5011308A (en) * | 1988-05-10 | 1991-04-30 | Tokyo Electric Co., Ltd. | Releasing type dot printer head |
US4929101A (en) * | 1988-05-27 | 1990-05-29 | Tokyo Electric Company, Ltd. | Release-type dot print head |
EP0385047A1 (de) * | 1989-03-01 | 1990-09-05 | MANNESMANN Aktiengesellschaft | Matrixdruckkopf mit einem Elektromagnetspulenträger |
US5080510A (en) * | 1989-03-01 | 1992-01-14 | Mannesmann Aktiengesellschaft | Matrix print head with an electromagnetic coil support |
DE4338655A1 (de) * | 1993-03-17 | 1994-09-22 | Fujitsu Ltd | Magnetgrundkörper für Druckkopf von Nadeldrucker und Verfahren zum Herstellen desselben |
DE4338655C2 (de) * | 1993-03-17 | 1998-11-19 | Fujitsu Ltd | Druckkopfkern für einen Nadeldrucker und Verfahren zum Herstellen desersteren |
Also Published As
Publication number | Publication date |
---|---|
DE3167553D1 (en) | 1985-01-17 |
IT1131146B (it) | 1986-06-18 |
EP0041126B1 (de) | 1984-12-05 |
IT8021815A0 (it) | 1980-05-06 |
EP0041126A3 (en) | 1982-07-14 |
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