EP0014737A1 - Commande électromagnétique - Google Patents

Commande électromagnétique Download PDF

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Publication number
EP0014737A1
EP0014737A1 EP79104186A EP79104186A EP0014737A1 EP 0014737 A1 EP0014737 A1 EP 0014737A1 EP 79104186 A EP79104186 A EP 79104186A EP 79104186 A EP79104186 A EP 79104186A EP 0014737 A1 EP0014737 A1 EP 0014737A1
Authority
EP
European Patent Office
Prior art keywords
permanent magnet
actuating element
magnetic
magnetic core
magnetic flux
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
Application number
EP79104186A
Other languages
German (de)
English (en)
Other versions
EP0014737B1 (fr
Inventor
John Carl Tamulis
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.)
International Business Machines Corp
Original Assignee
International Business Machines 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 International Business Machines Corp filed Critical International Business Machines Corp
Publication of EP0014737A1 publication Critical patent/EP0014737A1/fr
Application granted granted Critical
Publication of EP0014737B1 publication Critical patent/EP0014737B1/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
    • B41J9/00—Hammer-impression mechanisms
    • B41J9/26—Means for operating hammers to effect impression
    • B41J9/38—Electromagnetic means

Definitions

  • the invention relates generally to an electromagnetic actuating device of the type in which the actual actuating element or the armature is held tensioned against a prestressing force and can be triggered selectively for a working stroke.
  • magnetic actuators are used to drive the print hammers and use compensation coils that counteract the excitation of the force attracting the hammer and thus release the hammer to stop.
  • the tripping current for the compensation coil is relatively high, so that additional components are required to control the driver circuits for the windings of the print hammer magnet. These components naturally cause additional effort in comparison to the production of the driver stages in integrated circuit technology, as is the case with most pressure control circuits today.
  • the object of the invention is therefore to provide an electromagnetic actuating device in which the actuating element is held by a cyclically changing magnetic flux density and is then released or triggered by a compensation coil when the flux density passing through the compensation coils is at a low value.
  • the compensation coil is to be arranged in a magnetic circuit in such a way that the opposing magnetomotive force lies in series and in phase with the magnetomotive force which is generated by the current pulse at the time the actuating element is triggered.
  • the new actuation device is to be equipped with a permanent magnet which is arranged movably with respect to the magnetic core and which generates a cyclically changing flux density at the point at which the actuation element is held by the magnetic attraction force and at which the excitation of the compensation coil is timed to coincide with the time when the flux density at the actuator and the compensation coil is at a low value.
  • a magnetic core structure which has a first and a second pair of poles, the one pair of poles being used to hold a spring-loaded actuating element in a tensioned position and the other pair of poles in the immediate vicinity of a permanent magnet carrying out a relative movement lies, which thus generates a cyclically changing flux density in the first pole pair that holds the actuating element.
  • the magnetic core has a center leg on which a compensation coil is wound, which can be selectively excited when the flux density is at a low value, whereby the holding flux for the actuating element is further reduced, so that it can detach from the pole faces.
  • the permanent magnet can either move back and forth or change to change the air gap and thus cyclically change the magnetic resistance between the permanent magnet and the core to generate a cyclically changing flux density on the pole faces of the pole pair that hold the actuating element.
  • the compensation coil is activated in such a way that it is excited when the magnetic resistance has approximately reached its highest value, so that the compensation coil is therefore always excited when the flux density is at its lowest.
  • the magnetic actuation device consists of a core 10, and an armature or actuation element 11, a reciprocating permanent magnet 12 and a compensation coil 13.
  • the core 10 is made of a magnetically permeable material and has a first pair of poles 14, 15 second pole pair 16, 17 and a middle leg 18.
  • the actuating element 11 is preferably made of magnetically permeable material and can consist, for example, of spring steel, although this is not absolutely necessary.
  • the actuating element must in any case have a magnetically permeable plate 20 which can be attracted by the pole faces of the pole pair 14, 15.
  • the actuating element 11 is clamped at its lower end and either shaped or arranged in such a way that it is biased relative to a rest position shown in broken lines. In the drawing the actuator 11 carries a print hammer 21 for use in a printer.
  • the permanent magnet 12 is U-shaped and has two pole faces 24, 25, which correspond to and oppose the pole pair 16, 17 of the magnetic core 10, and is slidably arranged on a pair of rails 26 for a reciprocating movement with respect to the magnetic core .
  • the permanent magnet 12 can be moved approximately in the manner shown by a push rod 27, which is articulated eccentrically on a rotating disc, which in turn is fastened on a shaft 29 which can be driven by a motor (not shown).
  • the shaft 29 also carries a disk 30 provided with slits 31, the slits 31 being sensed, for example, by a photodetector 32. This photodetector supplies a gate switching signal to a control circuit 33 which, in conjunction with a trigger command, causes the compensation coil 13 to be energized.
  • the rotation of the shaft 29 and the disk 28 mounted thereon cause the permanent magnet 12 to move back and forth with respect to the magnetic core 10.
  • the magnetic flux passing through the magnetic core provides the attractive force for the actuating element 11 on the pole faces of the pole pair 14, 15, thereby the actuator 11 is held in the position shown in solid lines.
  • the limit of the reciprocating movement or the greatest expansion of the air gap D between the permanent magnet and the magnetic core is determined by the flux density of the magnetic flux that is required to hold the actuating element in the position shown.
  • the maximum allowable air gap width is that which is required to keep the actuator just in the position shown by solid lines.
  • the smallest air gap is again the one that is required is to attract the actuator from a free-standing position.
  • the flux density changes cyclically in the first pole pair as well as in the middle leg between a first high value 35 and a second low value 36 in FIG. 2a.
  • a trigger command is supplied to the control circuit 33 to excite the compensation coil 18.
  • This triggering command is controlled in such a way that it takes effect simultaneously with the point in time at which the magnetic flux at the pole faces of the pole pair 14, 15 opposite the actuating element 11 is at a low value. This coincidence is determined by the position of the slots 31 of the clock disk and by the photodetector 32. At this time, only a small current flowing through the compensation coil 13 is required so that the actuating element can be triggered. It is assumed that the direction of flow from the north pole of the permanent magnet runs through the middle leg 18 of the magnetic core and through the parallel flow path from pole 14, block 20 and pole 15 and from there to the south pole of the permanent magnet.
  • the compensation coil 13 When excited, the compensation coil 13 supplies an additional magnetic flux in the same direction as the flux generated by the permanent magnet in the middle leg. However, the newly generated magnetic flux is distributed over two flux paths, one running over the south and north poles of the permanent magnet and back, while the greater part of the additional magnetic flux is directed in the opposite direction and the original flux through the first pole pair 14, 15 the actuating element is entge- genge toys. 1 This creates a compensation flow in this leg, so that at point 37 (Fig. 2a) the holding flow is reduced so far that the actuating element 11 moves to the position shown in dashed lines.
  • the optimal time for the excitation of the compensation coil is at point 37, where the tripping current 38 then coincides with the lowest value of the flux density through the pole shoes of the pole pair 14, 15. This effect therefore requires the smallest compensation current for actuating the actuating element.
  • the movement of the actuator from its biased position is shown at 39 (Fig. 2c).
  • the current is only briefly applied to the compensation coil, so that the magnetic flux passing through the permanent magnet exerts an attractive force on the actuating element rebounding after the impact and brings it back again from the release position.
  • the permanent magnet can be used to retighten the actuator, other devices such as an additional coil or a mechanical reset device can be used to reset the actuator.
  • the magnetic actuation device can also be constructed as shown in FIG. 3.
  • a rotating permanent magnet is used, which causes a cyclical change in the magnetic flux flowing through the actuating element that is attracted.
  • the magnetic core 40 is shown here in a different plane than in FIG. 1, but also has a central leg 41, a first pair of poles 42, 43 and a second pair of poles 44, 45.
  • the compensation coil 46 is in turn mounted on the central leg 41.
  • the actuating element 47 has a magnetically permeable block 48 which is attracted by the magnetic flux occurring at the first pole pair 42, 43 against the bias of the spring 49.
  • the exciting magnetic flux is generated by a permanent magnet 50 which is arranged on a rotatable shaft 51 which also carries the clock disk, not shown.
  • the permanent magnet is provided with grooves 52 and changes the density during its rotation of the magnetic flux passing through the core, the pole faces and thus also the middle leg and the pole faces holding the actuating element.
  • the compensation winding can be excited in connection with the clock arrangement in FIG. 1 and releases the actuating element at the time of the lowest flux density. As a result, the compensation coil can be driven with a relatively low current.
  • the actuating device can still be modified somewhat in terms of construction, and other arrangements for a relative movement between a permanent magnet and the magnetic core are conceivable, or additional reset windings could be provided.
  • the various pole faces may also be coated with a non-magnetic material to prevent the relatively moving parts from sticking.
  • a plurality of magnets can also be used.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Electromagnets (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
EP79104186A 1978-12-29 1979-10-29 Commande électromagnétique Expired EP0014737B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US974298 1978-12-29
US05/974,298 US4224589A (en) 1978-12-29 1978-12-29 Low energy magnetic actuator

Publications (2)

Publication Number Publication Date
EP0014737A1 true EP0014737A1 (fr) 1980-09-03
EP0014737B1 EP0014737B1 (fr) 1983-01-19

Family

ID=25521866

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79104186A Expired EP0014737B1 (fr) 1978-12-29 1979-10-29 Commande électromagnétique

Country Status (8)

Country Link
US (1) US4224589A (fr)
EP (1) EP0014737B1 (fr)
AU (1) AU527732B2 (fr)
BR (1) BR7908327A (fr)
CA (1) CA1124780A (fr)
DE (1) DE2964555D1 (fr)
ES (1) ES486095A1 (fr)
IT (1) IT1163744B (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4392423A (en) * 1978-02-08 1983-07-12 Hitachi, Ltd. Printing hammer driving apparatus
US4461207A (en) * 1980-11-17 1984-07-24 International Business Machines Corporation Actuator mechanism for a printer or the like using dual magnets
JPS57191079A (en) * 1981-05-20 1982-11-24 Seikosha Co Ltd Printer head
US4423675A (en) 1982-03-08 1984-01-03 Hewlett-Packard Company Magnetic circuit and print hammer
US4441421A (en) * 1982-09-22 1984-04-10 Hossein Khorsand Print hammer apparatus
US5199804A (en) * 1991-05-31 1993-04-06 Smith Corona Corporation Quiet impact printer mechanism
JPH1042544A (ja) * 1996-03-15 1998-02-13 Eastman Kodak Co 電磁的アクチュエータに用いるための軟磁性材料製コア

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1279837B (de) * 1962-10-08 1968-10-10 Landis & Gyr Ag Elektromagnetisches Haft-Relais

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3146381A (en) * 1960-09-12 1964-08-25 Vente D Aimants Allevard Ugine Magnetic force control or switching system
JPS5740522B2 (fr) * 1974-01-18 1982-08-28

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1279837B (de) * 1962-10-08 1968-10-10 Landis & Gyr Ag Elektromagnetisches Haft-Relais

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
IBM TECHNICAL DISCLOSURE BULLETIN, Band 21, Nr. 4, September 1978, New York H.G. SEIFERT "Print Hammer with Synchronous Energization" Seite 1510 * Fig. * *

Also Published As

Publication number Publication date
CA1124780A (fr) 1982-06-01
DE2964555D1 (en) 1983-02-24
BR7908327A (pt) 1980-09-16
AU5353579A (en) 1980-07-03
EP0014737B1 (fr) 1983-01-19
AU527732B2 (en) 1983-03-17
IT7928241A0 (it) 1979-12-20
IT1163744B (it) 1987-04-08
ES486095A1 (es) 1980-09-01
US4224589A (en) 1980-09-23

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