US3156180A

US3156180A - Permanent magnet hammer module in high speed printers

Info

Publication number: US3156180A
Application number: US138991A
Authority: US
Inventors: Hugh R Barnes
Original assignee: Holley Computer Products Co
Current assignee: Holley Computer Products Co
Priority date: 1961-09-18
Filing date: 1961-09-18
Publication date: 1964-11-10
Anticipated expiration: 1981-11-10

Description

H. R. BARNES Nov. 10, 1964 PERMANENT MAGNET HAMMER MODULE IN HIGH SPEED PRINTERS Filed Sept. 18, 1961 INVENTOR.

HUGH R. BAR/V5.5

ATTORNEY IPERMANENT 'MAGNETJHAMMER MODULE I l j l INHIGH SPEEDPRINTERS V Hugh R.'"Barnes', St; Clair Shores, Mich, assiguor, by

mesne assignments, to Holley Computer 'ProdnctsCom -pany; Warren,-Mich.,.a-corporation of Michigan Filed Sept. 18, 1961, Ser. N0.-138,99 1--;

. 3 Clairns. ((31,.101-93).

.This invention relates to speedl printers', andtp'articularly. tov novel electromechanical, OH-thCrflY. type printer.. 1 I.

More specifically,thisinvention relatesto ajmodification. of the print .hammerme'chanism. disclosed mus;

, Printer, and-filedon September.;14,. 1961, in.the-n'ames,,

application Serial,No. 138,157, entitled .HighgSpeed of Arvin D. McGregor'and, James M. Irvine, Jr. f

.In the-.abovereferenced. application, the, disclosure or whichis hereby. incorporated by reference each print hammer 160112111 associated therewith electromagnet, 226.comprising two.windings,..one .of the windings being,

termeda holding coil andthe otherwinding being termed a pulse. coil .The holding (foil was, continuously energized whenever the .p'rinter power was turnedljofrn, and. the purpose thereof was to hold the print hammer. interposer mechanism .in. the. non-print position, .Additionallyaddressing any givenprint hammer forprinting inf,

volved energizing the pulse coil of the electromagnet associated with thatp'articular ,ha'rnrnerso as to cancel out the magnetic field ofthe holding coiland thereby permit the hammer 'interposer system to move to the print position. The-printer disclosed in the above ref erenced""applicationalso containeda bail bar '243,the purpose of which was to return the hammer interposer system'to 'the-non-printposition upon the shut-down theprinter and immediately'upon restarting the printer;

The main-feature of-this invention is the substitution of a permanent magnetfor the holding coil in the print hammer mechanism disclosed' inthe above referenced application. t s 1 Accordingly, one object of the invention is to provide a print hammer mechanism in which no exterior source of electrical power is required to hold the print hammer interposer system in the non-print position.

Another object of the invention is to provide a print hammer mechanism in which the printer interposer system is held in the non-print position even with the printer power turned off, thus making it possible to eliminate the bail bar and all elecrtonic and mechanical parts associated with the bail bar.

Another object of the invention is to provide a print hammer mechanism which is relatively inexpensive to construct and less likely to require repair. 7

These and other objects of the invention will become more apparent upon reference to the following specification and the attached drawings wherein:

FIGURE 1 is a fragmentary part elevational and part cross-sectional view illustrating a print hammer mechanism embodying the invention;

FIGURE 2 is a cross-sectional view taken on the plane of line 22 of FIGURE 1 and looking in the direction of the arrows;

FIGURE 3 is a fragmentary cross-sectional view taken on the plane of line 33 of FIGURE 1 and looking in the direction of the arrows.

Referring now to the figures in greater detail, FIGURE 1 is a view very similar to FIGURE 6 of the above referenced application, and all elements common with those in the above FIGURE 6 will be identified with the same reference numbers. Thus, the'hammer module assembly 196', which may be completely interchangeable with module 1% of application Serial No. 138,157, comprises a base plate 197 on which the four hammer actuating levers 215 are' mounted, As before, each lever 215 has an arm 219.cooperating with the free end of the interposerlever 1822, sometimes referred to as a beaver tailv 182, whi'ch is pivotally connected to the print hammer 160. ,The spring 186 urges the be'avertail 182 downwardly so that a lobe 241 of thecam 168 may impact the beaver tail 182 and'dri've the hammer 160 into the print drum 109 when the hammer is addressed for printing.

As explained in the aboyereferenced application, each actuating lever215 has a second arm to which there is attachedan armature224, the armaturebeing provided? to holdthe actuating lever 215, and thus the beaver tail;

andhammerassembly, in the non-print position until the.

hammer isv addressed. 1

,In, the Serial 110,138,157 construction, each hammer k beavertail132 and actufatingjlever 215' comprised an inj tel-poser system andhad associated therewith an GlCCiIfQ-f magnetf226 having two windings, a holding coil which is continuously energizedand a pulse coil which is energized' only when the hammer in question was addressed for'printing so as to releasethe armature 224 and allow the spring 186 to moye 'the interposer system into the '1 path of the] cam 108.

1n th'e modified construction in FIGURE S l I and 2,'the electromagnet associated with each of the hammer mechanisms isreplaced by a combination perj manent magnet. and pulse coilassembly 10. The four assemblies 111, are mounted on the base plate.197 in an arcuate pattern just as the 'electromagnets 226 were "mounted, and each assembly lqincludes a permanent magnet 12 of predetermined magnetic force and a suitably formed pole piece 14 mounted on the magnet'in magnet, the edges 16 and 17 of whichattract and hold thejarmature 224 of the actuating lever 215 in the:

position shown in FIGURE 1 against the force of the spring 186. Edge 16 is on the pole piece, while edge 1'? is provided by an opening 19 in the base plate 197.

A pulse coil 18 is mounted on the leg 20 of the pole piece 14. The permanent magnet 12, to which the pole piece 14 is attached, provides a force of attraction which holds the armature 224 of the lever interposer system in a non-print position against the leg 26 The pulse coil 13 is wound in a particular direction so that when current is passed through the coil 18, the resultant magnetic field is in a direction opposite to that of the magnetic field of the permanent magnet 12. This serves to, decrease the magnetic field in the pole piece 14 and in the armature 224 to the extent that the force of the spring 186 now exceeds the magnetic force and is thus capable of pivoting the actuating lever 215, and hence, the armature 224, away from the pole piece 14.

With the exception of the above specific construction described above, the other remaining details of the hammer module 1% shown herein may be exactly the same as that of the hammer module 196 disclosed in application Serial No. 138,157. This being so, the hammer module 196' could be substituted directly for the hammer module 1% of the above referenced application.

piece 14 is a part of a permanent horseshoe magnet haviug sufficient strengthto retain the armature 224 against P t nt d w- 10, 4;

the force of the spring 185, the armature 224- will be retained by the pole piece until the pulse coil 18 is energized when it is desired that that particular hammer print a character, this being accomplished in the same manner as described in Serial No. 138,157. When coil 18 is energized, thus cancelling the holding force of the permanent magnet in the manner described above, the armature 224 is released and the spring 186 pulls the interposer assembly comprised of the actuator lever 215 and the beaver tail 182 downwardly to the stop 21 so that a cam lobe 241 may strike the surface 183 of the beaver tail, after which the next succeeding cam lobe will strike surface 242 of the arm 219 and rotate the actuator lever 215 to the non-print position.

With this modified construction, it is apparent that no external power is required to energize a separate holding coil when the printer is turned on or off. Since the permanent magnets 12 provide a permanent holding force that exists even when the printer is turned off, all of the actuating levers 215 will be in the non-print position shown in FIGURE 1 at all times, except when the pulse coil 18 is energized. Momentum or the inertia of the cam 103 at the end of the print cycle will return all actuating levers to the FIGURE 1 position before the printer is turned off; thus, the bail bar 243 provided in the printer disclosed in application Serial No. 138,157 and all the parts associated therewith are not required and can be eliminated to reduce the overall cost of the printer. Since all of the actuating levers will be retained in the non-print position at all times when the printer is shut off, it is apparent that meaningless lines of print will not occur when the printer is subsequently turned on.

It should be apparent that certain modifications may be made without exceeding the scope of the following claims.

What I claim as my invention is:

1. In an electromechanical printer having a print drum, a movable print hammer having one end confronting said drum, a first lever having an impact surface and pivoted to the opposite end of said hammer, means to mount and to constrain the movement of said hammer in excursions toward and away from said drum, a mounting plate, a second lever having an impact surface and pivoted to said plate for movement in a plane coplanar with the plane of said first lever, said second lever having a first arm opcratively associated with said first lever to form a cooperating lever system, resilient means operatively connected with a lever of said system in a manner such that said levers are normally biased to a print position, a cam adapted to strike the impact surface of one of said levers and thereby drive said hammer toward said drum when said levers are in said print position, said cam also adapted to strike the impact surface of the other of said levers to position said levers in a non-print position after said hammer is driven toward said drum, said second lever having a second arm, a stationary permanent magnet structure adjacent to said second arm, an armature attached to said second arm, said armature holding said lever system in said non-print position against the force of said resilient means when said armature is in engagement with said permanent magnet structure, a bucking coil associated with said permanent magnet structure, and said coil when energized adapted to reduce the armature-holding force of the magnet structure an amount snlficient to release the armature under the influence of said resilient means thereby enabling said resilient means to pivot the levers of said lever system to said print position at which said cam sequentially engages said levers.

2. The subject matter of claim 1 wherein said permanent magnet structure includes a permanent magnet core, a pair of pole pieces in flux linkage with said core and having a pair of spaced free ends, and said armature bridging said free ends when engaged with said permanent magnet structure thereby forming a closed-loop magnetic circuit.

3. The subject matter of claim 2 wherein one of said pole pieces is composed of a part of said mounting plate.

References Cited by the Examiner UNITED STATES PATENTS 2,056,745 10/36 Stalmaker 317-172 2,178,289 10/39 Snavely a- 317172 X 2,766,686 10/56 Fomenko et a1. 2,892,954 6/59 Orlando 317-172 2,897,752 8/59 Nlfiln'llOS.

2,930,889 3/60 Hours 317172 2,949,846 8/60 Hoffman et al. 3,049,990 8/62 Brown et a1.

WlLLIAM B. PENN, Primary Examiner.

Claims

1. IN AN ELECTROMECHANICAL PRINTER HAVING A PRINT DRUM, A MOVABLE PRINT HAMMER HAVING ONE END CONFRONTING SAID DRUM, A FIRST LEVER HAVING AN IMPACT SURFACE AND PIVOTED TO THE OPPOSITE END OF SAID HAMMER, MEANS TO MOUNT AND TO CONSTRAIN THE MOVEMENT OF SAID HAMMER IN EXCURSIONS TOWARD AND AWAY FROM SAID DRUM, A MOUNTING PLATE, A SECOND LEVER HAVING AN IMPACT SURFACE AND PIVOTED TO SAID PLATE FOR MOVEMENT IN A PLANE COPLANAR WITH THE PLANE OF SAID FIRST LEVER, SAID SECOND LEVER HAVING A FIRST ARM OPERATIVELY ASSOCIATED WITH SAID FIRST LEVER TO FORM A COOPERATING LEVER SYSTEM, RESILIENT MEANS OPERATIVELY CONNECTED WITH A LEVER OF SAID SYSTEM IN A MANNER SUCH THAT SAID LEVERS ARE NORMALLY BIASED TO A PRINT POSITION, A CAM ADAPTED TO STRIKE THE IMPACT SURFACE OF ONE OF SAID LEVERS AND THEREBY DRIVE SAID HAMMER TOWARD SAID DRUM WHEN SAID LEVERS ARE IN SAID PRINT POSITION, SAID CAM ALSO ADAPTED TO STRIKE THE IMPACT SURFACE OF THE OTHER OF SAID LEVERS TO POSITION SAID LEVERS IN A NON-PRINT POSITION AFTER SAID HAMMER IS DRIVEN TOWARD SAID DRUM, SAID SECOND LEVER HAVING A SECOND ARM, A STATIONARY PERMANENT MAGNET STRUCTURE ADJACENT TO SAID SECOND ARM, AN ARMATURE ATTACHED TO SAID SECOND ARM, SAID ARMATURE HOLDING SAID LEVER SYSTEM IN SAID NON-PRINT POSITION AGAINST THE FORCE OF SAID RESILIENT MEANS WHEN SAID ARMATURE IS IN ENGAGEMENT WITH SAID PERMANENT MAGNET STRUCTURE, A BUCKING COIL ASSOCIATED WITH SAID PERMANENT MAGNET STRUCTURE, AND SAID COIL WHEN ENERGIZED ADAPTED TO REDUCE THE ARMATURE-HOLDING FORCE OF THE MAGNET STRUCTURE AN AMOUNT SUFFICIENT TO RELEASE THE ARMATURE UNDER THE INFLUENCE OF SAID RESILIENT MEANS THEREBY ENABLING SAID RESILIENT MEANS TO PIVOT THE LEVERS OF SAID LEVER SYSTEM TO SAID PRINT POSITION AT WHICH SAID CAM SEQUENTIALLY ENGAGES SAID LEVERS.