US3705370A - Magnetically actuated and restored print hammer - Google Patents

Magnetically actuated and restored print hammer Download PDF

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Publication number
US3705370A
US3705370A US134176A US3705370DA US3705370A US 3705370 A US3705370 A US 3705370A US 134176 A US134176 A US 134176A US 3705370D A US3705370D A US 3705370DA US 3705370 A US3705370 A US 3705370A
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US
United States
Prior art keywords
armature
leg
surface portion
outer leg
cylindrical surface
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
US134176A
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English (en)
Inventor
Hi D Chai
Stephen H Mills
Joseph P Pawletko
Francis E Peters
Carl T Young
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
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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
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Publication of US3705370A publication Critical patent/US3705370A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K33/00—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/14—Pivoting armatures

Definitions

  • a magnetic actuator comprises a three-legged mag- [21] Appl 134,176 netic core with an armature pivotally mounted at the middle leg to have portions on either side thereof with i an abutting gap relation with one outer leg and an ⁇ 2% 8''. 335/229 3 8 abutting plus a peripheral gap relation with the other. [58% n A winding on the one abutting leg provides drive flux and a winding or permanent magnet on the other leg provides a restore or detent flux between teeth on the armature and core.
  • Another object of the invention is to provide an electromagnetically operated print hammer having a single movable element.
  • Yet another object of the invention is improving the settle-out time of a operated print hammer.
  • Another object of this invention is to provide for combining a variabl e reluctance constant length air gap with a variable length variable reluctance air gap in the restore magnetic circuit of an electromagnetically operated print hammerin order to improve the restore characteristics of the print hammer.
  • Yet another important object of this invention is to provide for reducing the restore time of an electromagnetically operated print hammer and also reduce the likelihood of rebound upon restoration to the. nonoperated position.
  • FIG. 1 is a schematic view in side elevation of a magnetically operated print hammer embodying the invention in one form
  • FIG. 2 is a schematic view in side elevation of a magnetically operated print hammer embodying the invention in a different form; I 1 1 FIG. 3 is a chart showing torques acting on the armature of the actuator for different positions of the arma ture; and e to provide for magnetically FIG. 4 is a schematic equivalent magnetic circuit diagram for the print hammer of FIG. 2.
  • DESCRIPTION OF PREFERRED EMBODIMENTS has a cylindrical Surface Portion 16 which cooperates with a corresponding cylindrical Surface Portion 17 of an Armature 18, which is typically mounted at or adjacent the Middle Leg 14 by means of a Pivot Shaft 20, and has an upwardly-extending Arm or Actuator Portion 22, shown disposed in predetermined'spaced relation with the end of the Upper Leg 13 to-defme an air gap G2.
  • the. Extension 22 is provided with a Hammer Face 24 for impacting a Document 26 and a Ribbon 28 against a Type Member 30, which may be mounted on a belt or the like (not shown) for movement past a print position.
  • the lower end of the Armature 18 may be provided with a hooked portion providing a Pole Piece 32, which cooperates with the Lower Leg 15 and is shown in substantially abutting relation therewith.
  • the Upper Leg 13 of the Core Member 12 may be provided with a winding or the like for providing a detent flux or, as shown, may comprise a Permanent Magnet 11 to supply magnetic flux for normally attracting the Armature 18 to a rest position in abutting relation therewith.
  • An Operating Winding 34 is provided on the Lower or Drive Leg 15 and, as shown, is positioned to surround the end portion of the Pole Piece 32 of the Armature 18 so that the air gap G1 between the lower end of the armature 18 and the Lower Leg 15 will be within the confines of the Winding 34.
  • The'Middle Leg 14 in addition to having the cylindrical Surface Portion 16, has an adjoining relatively flat radial Pole Face or Surface Portion 40, which cooperates with a corresponding relatively flat radial Pole Face or Surface Portion 42, on the Armature 18 to provide abutting Pole Faces.
  • the Armature 18 will normally be held in abutting .relation with the Upper Leg 13 because of magnetic flux produced by the Permanent Magnet 11, which follows a path through the Upper and Middle Legs-l3, 14 and the intermediate portion of the Armature 18.
  • the Winding 34 is pulsed, sufficient magnetic flux is produced between the Lower Leg l5 and the Lower-End 32 of the Armature 18 to overcome the holding effect of the Permanent Magnet 11, causing the Armature 18 to rotate in a clockwise direction, closing the gap G1 and causing the Hammer Face 24 to impact the Paper 26 and Ribbon 28 against the Type 30 for printing.
  • the pulse applied to the Winding 34 is terminated, the magnetic flux produced by the Permanent Magnet 1 l is sufficient to restore the Armature 18 to the non-operated position against the end of the Permanent Magnet 11.
  • the reference numeral 41 designatesa generally similar Electromagnetic Actuator comprising a three-legged magnetic Core 44 having Upper, Middle and Lower Leg Portions 46, 48 and 50, and an Armature 52 pivotally mounted by means of a Pivot 54 opposite a cylindrical End Portion 56 of the Middle Leg 48, much the same as described in connection with the actuator of FIG. 1.
  • the Armature 52 likewise has an upstanding Arm or Actuator Portion 58, which carries at its upper end a Hammer Face 60.for impacting a document, ribbon and type as described in connection with the actuator of FIG. 1.
  • the Armature 52 is provided with a hooked End Portion 62 at the lower end, which defines with the Lower Leg Portion 50 a substantially radial air gap G1 located within the confines of an Operating Winding 64.
  • an adjoining substantially flat radial Pole Face 66' is provided adjacent the cylindrical end of Fortion 56 of the Middle Leg 48 and a corresponding Pole Face 68 is providedon the Armature 52.
  • the Upper Leg Portion of the Electromagnetic Core 44 may comprise a' Permanent Magnet 43 as was the case in connection with the actuator of FIG. 1.
  • a Pole Piece 70 is provided at the end of the permanent magnet.
  • the Pole Piece 70 has a Pole Face 71 defining with the Armature 52 the air gap G2.
  • the Pole Piece 70 has a curved peripheral Face 72 definedv by a plurality of spaced Teeth 72a 72d.
  • the Armature 52 is provided with a corresponding peripheral curved Portion 74 having a similar arrangement of spaced Teeth 74a 74d.
  • the steady-state magnetic flux produced by the Permanent Magnet 43 effects the restore of the Armature 52 in a counterclockwise direction as soon as the energization ofth e Operating Winding 64 is terminated.
  • the effects of the parabolic torque characteristic of the Teeth 72a 72d, and 74a 74d and the square law characteristic of the radial or abutting gaps may be seen by reference to the curves T01, T63 and TG2 and Tr of FIG. 3, which show respectively the torques on the armature, namely, the torque of the Pole Face G1, plus G3, the torque of Pole Face G2, and the torque of the restore Teeth 72a 72d, and 74a 74d.
  • R1, R2, and R3 Reluctances between the points P and Q to the lower, upper and middle legs, respectively.
  • R2 is given by:
  • Rm is the magnet and iron reluctance
  • R! and Rg2 are the reluctance between flat pole faces and the reluctance between the stator and armature teeth, respectively.
  • R3 R3+RcX(Rg3/Rc-l-Rg3) (la) where R3 is the iron reluctance in the middle leg between P and Q; Re is the reluctance of the fixed circular gap, and R33 is the reluctance of the flat pole face.
  • Tgl, Tg2, Tg3, T are the torques at the lower pole face, upper pole face, middle pole face, and teeth, respectively. They are given by:
  • Equation (8) results from the assumption that the teeth gap reluctance varies sinusoidally, and the torque on the armature in the counterclockwise direction is positive. k is a constant to be determined for the assumed reluctance variation.
  • F1 is zero
  • #2 is larger than (111, and the torque is positive.
  • R3 is much smaller than R2, and very little flux derived from the drive pulse goes through the upper leg. Consequently, the drive pulses contribution to the counterclockwise torque is negligible.
  • the initial flux at the drive leg is non-zero. Since the rate of change of the drive torque (Tgl) is proportional to bl and dl/dt, a faster buildup of the torque is expected than in a situation where (#1 is zero.
  • the drive current is applied to the actuator until the desired impact energy is developed. It is then removed so that the current is zero at the time of impact.
  • the reluctance torque (T) is large, and this in turn causes the armature to restore faster and reduces the time the print head is in contact with the paper.
  • Tg2 which serves to impede the rebound at the backstop
  • typical data is as follows:
  • a three-legged magnetic core member having a cylindrical surface portion at the end of the middle leg, an. armature of magnetic material having a pivotal support adjacent the middle leg of said core member with a corresponding cylindrical surface portion concentric with said pivotal support and positioned in close relation with the cylindrical surface portion of said middle leg to provide a constant reluctance pin gap, said armature having portions extending on opposite sides of said pivotal support point positioned in spaced relation with the ends of the outer legs'of said core member with one of said portions extending beyond the end of one of said outer legs to provide an actuating arm, means for producing a restore magnetic flux in said one outer leg to hold said armature against the end of said one outer leg, and I an operating winding positioned on said other outer leg disposed to be energized to overcome the effects of the means producing said restore magnetic flux, whereby the armature is actuated to separate said armature from said one associated outer leg of said core member and operate said arm.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Impact Printers (AREA)
  • Electromagnets (AREA)
US134176A 1971-04-15 1971-04-15 Magnetically actuated and restored print hammer Expired - Lifetime US3705370A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US13417671A 1971-04-15 1971-04-15

Publications (1)

Publication Number Publication Date
US3705370A true US3705370A (en) 1972-12-05

Family

ID=22462105

Family Applications (1)

Application Number Title Priority Date Filing Date
US134176A Expired - Lifetime US3705370A (en) 1971-04-15 1971-04-15 Magnetically actuated and restored print hammer

Country Status (7)

Country Link
US (1) US3705370A (cg-RX-API-DMAC7.html)
JP (1) JPS536695B1 (cg-RX-API-DMAC7.html)
CA (1) CA948256A (cg-RX-API-DMAC7.html)
DE (1) DE2215014A1 (cg-RX-API-DMAC7.html)
FR (1) FR2136042A5 (cg-RX-API-DMAC7.html)
GB (1) GB1331212A (cg-RX-API-DMAC7.html)
IT (1) IT946987B (cg-RX-API-DMAC7.html)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004505A (en) * 1973-11-06 1977-01-25 Compagnie Honeywell Bull (Societe Anonyme) Electromagnetic striker mechanism for a printer
US4282503A (en) * 1978-09-07 1981-08-04 Canon Kabushiki Kaisha Electromagnetic device
EP0022480B1 (de) * 1979-07-11 1983-06-01 International Business Machines Corporation Elektromagnetischer Druckhammerantrieb
US4392423A (en) * 1978-02-08 1983-07-12 Hitachi, Ltd. Printing hammer driving apparatus
US4493253A (en) * 1983-11-23 1985-01-15 Ncr Canada Ltd. Variable impact printing means
US4522122A (en) * 1983-05-03 1985-06-11 Ncr Canada Ltd - Ncr Canada Ltee Fast impact hammer for high speed printer
US4852481A (en) * 1988-07-14 1989-08-01 L. James Hubbard Print hammer mechanism

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4423675A (en) * 1982-03-08 1984-01-03 Hewlett-Packard Company Magnetic circuit and print hammer

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4004505A (en) * 1973-11-06 1977-01-25 Compagnie Honeywell Bull (Societe Anonyme) Electromagnetic striker mechanism for a printer
US4392423A (en) * 1978-02-08 1983-07-12 Hitachi, Ltd. Printing hammer driving apparatus
US4282503A (en) * 1978-09-07 1981-08-04 Canon Kabushiki Kaisha Electromagnetic device
EP0022480B1 (de) * 1979-07-11 1983-06-01 International Business Machines Corporation Elektromagnetischer Druckhammerantrieb
US4522122A (en) * 1983-05-03 1985-06-11 Ncr Canada Ltd - Ncr Canada Ltee Fast impact hammer for high speed printer
US4493253A (en) * 1983-11-23 1985-01-15 Ncr Canada Ltd. Variable impact printing means
US4852481A (en) * 1988-07-14 1989-08-01 L. James Hubbard Print hammer mechanism

Also Published As

Publication number Publication date
GB1331212A (en) 1973-09-26
DE2215014A1 (de) 1972-10-26
CA948256A (en) 1974-05-28
JPS536695B1 (cg-RX-API-DMAC7.html) 1978-03-10
IT946987B (it) 1973-05-21
FR2136042A5 (cg-RX-API-DMAC7.html) 1972-12-22

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