CA1046843A - Wire matrix ballistic impact print head - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The present invention relates to a high-speed matrix-type ballistic impact print head. High speed printers have been developed to accomodate the high output speed of information which can be delivered by high speed information handling systems. However, the printers are still relatively slow when compared to the speed of the electronics generating the information to be printed, A major problem encountered by the prior art is the physical space required to accomodate the actuators within the print head while maintaining the innertia of the print head as low as possible. Further, elec-tromagnetic actuator and stylus combination must be individually adjusted. The present invention provides an improved wire matrix ballistic impact print head for delivering printing impacts to a record medium under control of information format control circuitry, including a plurality of impact print styli, a guide for translating the plurality of styli from a circular arrangement at the impact delivering end of the styli, a plurality of electromagnetic actuators for selectively driving the styli during a print cycle of operation of the print head, and a unitary connector for maintaining the armature of each electromagnetic actuator in proper positional align-ment with a print stylus, for simultaneously adjusting all armatures to approximately the same de-energised position, for preventing bounce of the armature after an energized actuator Is de-energized and for establishing a reference plane to which all styli are referenced.

Description

The present invention relates generally to print-lng apparatus, and more particularly, to a high-~peed matrix-type ballistlc impact print head.
Hlgh speed printers have been developed to accom-modate the high output speed of in~ormation whlch can be delivered by high speed information handllng systems. The operational speed of such prlnters, however, 18 stlll a limit~ng factor as to the total e~ficiency of an lnformation handllng system ln that the prlnters are stlll relatlvely slow when compared to the speed of the electronics gener-atlng the in~ormation to be prlnted. Therefore, any im-provement whlch increa~es the operatlonal speed Or the printer has a marked effect on the overall efflclency Or the operatlng system.
Printers employlng wire matrix balllstlc impact prlnt heads provlde multlple hard coples of lnrormatlon at a relatively high speed. These printers are characterlzed ln that ror each prlnt cycl~ the prlnter does not print an entlre character per impact but instead use an array of wire otyll to prlnt selected comblnatlons of dots serlally onto the reaordlng medlum 80 that a~ the recording medlum is moved relative to the prlnt head, successive prlnt cycles generate alpha-numerlc characters or other lnformatlonal indicla.
One ma~or faotor dlctatlng the speed at which the wlre matrlx ballistlc lmpact print head 18 capable oP oper-atlng 18 the inertla as~ociated wlth the impacting styli and the electromechanlcal stylus armatures. Print heads oP
this type typlcally use a separate electromagnetlc actuator 30 Por each stylus withln the prlnt head. A ma~or problem encountered by the prlor art ln deslgning such heads 18 the physlcal space requlred to accommodate these actuators wlthin the prlnt head whlle malntaln~ng the lnertia oP the print head as low as posslble. F~rther, electromagnetlc actuator and stylus comblnatlon must be lndlvidually ad-Justed. Tl~us, the ad~ustment for making all styll strlke the record medium at approximately the same instant of time -during a print cycle ls more complex, dlfflcult and tlme consuming.
It is therefore an ob~ect of the present inventlon to provlde a hlgh speed wlre matrix balllstlc impact print ; head wherein the actuators are arranged in a circle so as to reduce the lnertia of the print head.
It 18 another ob~ect of the present invention to provlde a hlgh speed wlre matrix balllstlc lmpact print head whlch employs a unltary connector for holding the armatures of each actuator ln proper posltlonal allgnment --wlth lts assoclated stylus.
Another obJect of the present lnventlon is to pro-vlde a hlgh speed wlre matrix balllstlc impact prlnt head whlch employs a unltary connector for slmultaneously ad~ust-lng all the actuators wlthln the prlnt head such that all actuated styli strlke the record medium at substantlally the same lnstant of tlme.
; It 1B stlll another ob~ect of the lnventlon to --provlde a hlgh speed wire matrix balllstlc impact prlnt head havlng a shock absorbing medlum for preventing bounce of the actuator armature and/or stylus durlng the return por-tlon of a prlnt cycle thereby preventing spurlou3 lmprint-lng on the record medlum.
Brlefly~ the hlgh speed wlre matrix ballistic print head lncludes a plurallty of wlre styll inserted for 30 movement wlthln a guide. The gulde translates the clrcul~r ~ormatlon o~ the impact recelvlng ends of the styll to a stralght llne formatlon of the lmpact deliverlng ends of the styll. An indlvldual actuator 18 provlded for engaglng the -`-` 1046843 impact receiving end of each stylus. Aunitary connector is also provided which includes means for holding the armature in contact with a magnetic structure to form an actuator means for holding each armature in proper alignment with its associated stylus, means for simultaneously adjusting the air gap between the armature and the electromagnet of the actuator, means forming a reference surface for referencing all styli, and damping means for eliminating bounce of the armatures and styli after the actuators are deactivated during a print cycle.
An advantage of the present invention is that it minimizes the variance inlength of the styli, thereby allowing the simultaneous adjustment of the position of all styli within the guide.
Another advantage of the print head is that the print head includes a unitary multifunction connector instead of the plurality of individual connectors as in the prior art, thereby reducing the mass of the print head.
Still another advantage of the present invention is the use of a unitary connector for providing simultaneous adjustment of all actuators such that all of the styli strike the record medium at substantially the same time.
More particularly there is provided a wire matrix ballistic impact print head comprising: a base; N styli; N
electromagnetic structures mounted to said base, each said structure having an outer pole, a center pole coupled to said outer pole and a coil disposed around said center pole, each said structure being associated with one of said styli; N
armatures, each being associated with one of said structures and having a stylus engaging end; and a unitary connector coupled to said base and having a central portion and N arms extending radially outwardly therefrom, each of said arms having means for holding one of said armatures in contact with the ~ _3_ ` - ~046843 outer pole of one of said structures to form an electromagnetic actuator for transferring electromechanical energy to one of styli.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention illustrated in the several figures of the drawing.
Fig. 1 is a perspective view of a print head in -accordance with the present invention;
Fig. 2 is a cross-sectional view taken along the line 2-2 of Fig. 1 illustrating the major components of the print head;
Fig. 3 is a front elevational view of the guide -3a-shown in Fig. 1.
Flg. 4 is a plan vlew o~ the second translation element of the guide shown in Fig. 3;
Fig. 5 is a plan view of the third translation element of the guide shown in Fig. 3;
Flg. 6 is a bottom vlew ~ the fourth translatlon element o~ the gulde shown ln Fig. 3;
Fig. 7 is a ~chematlc diagram 3howing the elec-trical connectors of the actuator coils for the prlnt head 8hown in Flg. l;
Fig. 8 18 a plan view of the prlnt head shown in Fig. 1 wlth the unitary connector and the armatures of the actuators removed; and Flg. 9 ls a bottom vlew of the unltary connector -shown ln Flg. 1.
A prlnt head 10 ln accordance wlth the present inventlon is shown in Fig. 1 connected to control circuitry 12 by means of the wl~es 14 and a plug 16. A ribbon 18 ls dlsposed ln between the bottom of prlnt head 10 and paper 20.
Fig. 2 is a slde elevational cross-section view lllu~trating the ma~or components of the print head 10.
Only one actuator and one stylus læ shown ln order to simpllfy the drawing. It should be understood that nlne actuator/stylus comblnations, identlcal in structure to that shown in Fig. 2, are included wlthin the structure o~
print head 10.
A guide 22 is provided for recelving a stylus 24 and constraining lt to move along a curved path. The stylus 24 has a plastic cap 26 attached to its lmpact receiving end to enlarge the area of the impact recelving sur~ace.
Stylus 24 has a spring 28 disposed at its upper end which exerts an upward force upon cap 26 to resillently bias stylus 24 upwardly relative to gulde 22. ~ulde 22 includes four translational guide elements 32, 34 and 36, whlch accomplish the translation Or the nine styll 24 from a circulrr formation in the fir~t guide element 30 to a 3traight line formation in the fourth guide element 36.
The translation is accomplished by passlng each stylus 24 through a separate hole 38 in the first element 30, through a separate hole 40 ln the second element 32, through a separate h~le 42 in the third element 34 and into a deflned posltlon withln a bearing 44 of the fourth element 36.
Flg. 3 lllustrates a front elevational vlew Or gulde 22 showing a side wall 46 and a slde wall 48 termlna-tlng ln the fourth translation element 36. Slde wall 46 and sidewall 48 are provlded with two sets of faclng grooves 50 and 54 and 52 and 56 for receiving the edge~ of gulde elements 32 and 34, respectlvely. At one edge of sidewall 46 the grooves 50 and 52 extend deeper into the 31de wall to form keyways for receivlng the locating key tabs 64 and 6~ Or guide elements 32 and 34.
A pair Or mountlng flanges 58 and 60 extend later-ally from the upper ends of side walls 46 and 48. Gulde 22 18 conflgured circular in shape above flanges 58 and 60, and terminates ln a clrcularly apertured surrace whlch forms rirst guide element 30. A post 62 extends from the ~rst translation element 30.
Fig. 4 is a plan view of the second guide element 32 showing the styll gulde holes 40 arranged ln an elip-tlcal pattern. The key 64 extends from the slde of element 32 to orlentate the placement of element 32 wlth~n gulde 22 as mentioned above.
3o Fig. 5 i9 a plan vlew of the thlrd guide element 34 showing the location of the styll gulde holes 42. As - illustrated, the arrangement o~ the gulde holes 42 ls Or a generally elongated oval configuratlon more or less ` 1046843 intermediate the el~ptical configuration shown in Fig. 4 and the stra~ght line con~guration sho~n in Fig. 6. The key 66 extends from the si~de of element 34 for orientating the ~lement within the guide 22.
Fig. 6 is a bottom view of the fourth guide element 36 of guide 22 showing the location of bearing 44 within guide 22. Bearing 44 aligns the lower ends, the impacting ends, of the plurality of styli 24 in the desired linear arrangement.
The bearing 44 is of a material which resists wear, has a low coefficent of friction and has a low coefficent ~f thermal expansion.
Returning to Fig. 2, a base plate 70 is used as the base for the construction of the print head 10. Plate 70 is provided with a central aperture 72 through which the circular portion of guide 22 extends. A plurality of holes 83 are provided in the base plate 70 for mounting the nine actuators thereto. Guide 22 is connected to base plate 70 by meaas of the mounting flanges 58 and 60 which are affixed to the lower sur-face of plate 70.
; A coil 74, a center pole 76, a L-shaped outer pole 78 and an armature 80 ~o~ the electromagnetic actuators used in the print head. A hole 82 is provided in the horizontal leg of the L-shaped outer pole 78 for receiving the lower extremity of center pole 76. ~ole 82 has a diameter which is the same as the outer dimension of center pole 76 so as to p~ovide a forced fit therebetween. The center pole 76 of each actuator has a threaded lower end 84 which extends through the hole 83 in base plate 70.
The center pole 76 and outer pole 78 combination is held in place ~y a nut 86 threaded onto end 84.
A wiring/connector board 88 tsee also Fig. 1~ has an opening 90 provided therein for receiving an outer pole 78.
Board 88 also has an apeEture 92 through which the circular portion Or guide 22 extends. Nlne additlonal holes 93 are provided ln board 88 through whlch the nlne center poles 76 of the nine actuators pass. Coil 74 is mounted around the center pole 76 on each actuator and wlred to the wiring/connector board 88.
Flg. 7 ls a schematlc dlagram lllustratlng the electrlcal connectlon Or the actuator colls 74 to the board 88. The nine colls 74 are wired with one end Or each coil 74 commonly connected and the other end Or each coil 74 10 wired to a separate connection polnt on edge connector 91 which 1B formed lntegral wlth board 88 as shown ln Flg. 8.
In Flg. 8 a plan vlew Or the prlnt head 10 ls 3hown wlth armatures 80 and a unltary connector 94 removed.
In essence, Fig. 8 lllustrates the constructlon Or the print head 10 up to the polnt heretofore descrlbed. The nlne styll heads 26 are shown posltloned above the first gulde element 30 of gulde 22. Board 88 ls shown mounted between the colls 74 and the magnetlc structures formed by the center poles 76 and the outer poles 78 of the nlne actua- -20 tor~. Mounting holes 95 are provlded ln base plate 70 ~or mountlng the completed prlnt head 10 to a prlntlng sy~tem.
The post 62 of` gulde 22 has a threaded hole 96 provlded there ln.
Returnlng to Flg. 2, the unitary connector 94 18 mounted by mean~ Or a screw 97 and washer 98 to the post 62 Or guide 22. Connector 94 has a clrcular cnntral por-tlon 100 wlth an annular groove 102 provlded ln its bottom sur~ace. An 0-rlng 104 ls lnserted ln groove 102 to act as a shock absorber and to provlde a reference surface rOr the 30 stylus strlklng ends of the armatures 80.
Nine arms 106 extend rrom central port~on 100.
Each arm 106 has assoclated with lt a rirst armature re-celving ~tructure 108 and a second armature receivlng iO46843 structure 110. One end of each armature 80 ls recelved and held in place by structure 108 and the other end of each armature is received and gulded by structure 110. Where c onnector 94 is installed in the positlon shown, arms 106 apply forces to the cantilevered dlstal ends of the arma-tures causlng the ir stylus lmpactlng ends to rotate about the fulcrum formed by the top edge of pole 78 and upwardly lnto engagement wlth O-rlng 104. The heads 26 of the styli 24 are maintained in contact wlth the ends of armature~ 80 by means o~ the forces applled by the springs 28.
Fig. 9 ls a bottom view of the unitary connector 94 showlng one armature 80 located ln posltlon relative to one of the arms 106. On lts outermost end, the armature 80 has notches 112 and 114 which mesh wlth first and second walls 116 and 118 of the flrst recelvlng structure 108 of arm 106. The central portlon 100 has nlne armature re-celvlng ~tructure~ 110 formed around its perlphery. Struc-ture 110 ls formed by flrst and second walls 120 and 122.
At lts lnnermo3t extendlng end 126, armature 80 ls narrowed 80 that lt passes between the two walls 120 and 122 of the recelving structure 110. T,le O-rlng 104 provldes a refer-ence surface against whlch all of the armatures 80 are referenced.
TJnltary connector 94 serves six separate and dls-tlnct function~. Fir~t, lt holds each armature 80 in contact wlth outer pole 78 (at polnt 124) ~o as to complete the magnetic c1rcuit of the actuator as u~ed w~thin the print head 10. Second, lt acts as a resillent, force applying member applying a m,oment to armature 80 causing lt to tend to rotate about the outer p ole 78. Armature 80 ls thereby rockably mounted upon pole 78 wlth lts narrow end portlon 126 ln contact wlth the reference surface formed by O~rlng 104. Third~ the unitary connector acts -` 1046843 as a means ~or aligning the end 126 of armature 80 with the head 26 of stylu~ 24. Thls allgnment feature prevents undeslred lateral movement of armature 80 and insures that --armature 80 is in proper allgnlng contact with head 26.
Fourth, connector 94 acts as an ad~usting m~ans for simul-taneously ad~usting the alr gap between each of the arma-tures 80 (at point 128) and the correspondlng center poles 76 of the respectlve a¢tuators. As a result of thls ad-~ustment, the positlon Or all the styll 24 are unl~ormly ad~usted wlthln gulde 22. Flrth, connector 94 rorms a reference surface agalnst whlch the armatures 80 and head 26 o~ styll 24 are referenced such that all actuated styll 24 lmpact the record medlum at substantlally the same instant of time durlng a prlnt cycle. Slxth, the unltary connector 94 includes a shock absorbing 0-ring 104 whlch absorbs the energy o~ the armatures 80 and styli 24 as they return to their rest positions when the actuators are de-activated. The absorbtlon of the klnetic energy withln a ~rticular armature 80 and stylus 24 at the end of a prlnt cycle prevents the armature 80 or the stylus 24 from bounc-lng and thereby cau~ing spurlous lmprlnts followlng the print cycle.
Returning to Fig. 2, the screw 97 is passed through hole 130 and tlghtened into post 62. A~ screw 97 is tightened, the alr gap between center pole 76 and arma-ture 80 wlll decrease. At the same tlme the mo~ent exerted on armature 80 by arm 106 18 lncreased. By the Judiclous ad~ustment of screw 97 an optimum settlng can be obtained ror transmlttlng the most deslrable amount of energy into stylus 24 by armature 80 whlle malntainlng a deslrable speed o~ return Or armature 80 to lts rest posltions.
In the alternatlve, the two-pie¢e structure Or the outer pole 78 and center pole 76 could be replaced by a ~lngle, cast structure of sultable material. Further, if lncreased efflclency of the magnetic circuit is desired, addltional outer poles could be designed lnto the actuator t~ improve the magnetic circuit associated with the actua-tor. Here again, the multi-pole structure could be con-structed of a plurality of separate elements or could be made of a single cast structure o~ proper material. The base plate 70 could also be included into any casting so as to lower the cost of manufacturing.
Referring to Flg. 1, print head 10 is capable of generatlng nlne impresslons during each prlnt cycle. Alpha-numerlc characters or other lnformation i9 generated by a sequence of print cycles. For example, the letter "E" is formed by selectively activating various comblnatlon~ of the nlne styli 24 durlng five separate print cycles.
Normally, the top ~even styli 24 are u~ed to ganerate letters having no below-the-line pro~ections. Letters re-qulrlng below-the-llne formatlon are prlnted using ln addi-tlon the lower two styll. An example is that lllustrated 20 by the lower case letter "g".
me control circuitry 12 selects which combination of the nlne styli 24 will be actuated durlng each print cycle. In between each print cycle, the print head 10, in one printer embodiment, is moved one print increment wlth respect to the paper 20 and the ribbon 18. However, the relative movement can be made either by movlng only print head 10, or by moving only paper 20 and ribbon 18, or by moving the print head 10 and the paper 20 (and the rlbbon 18).
The smaller the print lncrement, the greater the resolution o~ information imprinted on paper 20. me printing speed of print head 10 allows high resolution information to be generated within a reasonable time. T;he --` 1046843 information generated may take the form o~ both upper and ; lower case printed letters, script, plctures, figures, mathematical notations, etc. - -Referrlng to Fig. 2, when the coil 74 is ener- -gized~ a magnetic flux is created which will cause armature 80 to be drawn into contact wlth center pole 76. The move-ment of armature 80 will transmit energy into stylus 24 causing the stylus 24 to move downwardly through guide 22.
The force imparted into stylus 24 causes it to move agalnst sprlng 28 and its lnertia causes it to continue to move downwardly out of contact wlth armature 80 after the armature bottoms out against pole 76. The impact delivering end of stylus 24 extends beyond bearing 44 and strikes the -record medium cau ing a dot to be imprlnted. The energy stored in the moving stylus 24 iæ partlally absorbed by the lmpacted medium and partially returned to stylus 24 aiding spring 21-in returnlng stylus 26 to lts rest posltion.
At approximately the same time that ttylus 24 is lmpacting the record medium, the coil 74 is de-energized.
The moment exerted on armature 80 by arm 10~ causes it to rotate away ~rom the center pole 76 and to return into conta¢t with 0-ring 104. The energy in the returning armature 80 and the stylus 24 is absorbed by the dampening material of the 0-ring 104 thereby preventing bounce Or either armature 80 or stylus 24, thus preventing spurlous imprints to be made during a prlnt cycle.
It has been found that optimum energy iB trans-mitted into the stylus 24 when the actuator's air gap ls set such that the impacting end of the armature 80 moves a 3o distance of .015 inch. It has also been found that the ` total distance moved by the stylus 24 should be approxl-mately .030 of an lnch so that the stylus ls ln ~ree flight ~or approximately .015 lnch. Accordingly, the clearance between the bottom of the prlnt head and the print medium should be set at approximately .030 inch.
While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in the form and detail may be made therein without departing from the spirit and scope of the invention.

Claims (8)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A wire matrix ballistic impact print head comprising: a base; N styli; N electromagnetic structures mounted to said base, each said structure having an outer pole, a center pole coupled to said outer pole and a coil disposed around said center pole, each said structure being associated with one of said styli; N armatures, each being associated with one of said structures and having a stylus engaging end;
and a unitary connector coupled to said base and having a central portion and N arms extending radially outwardly there-from, each of said arms having means for holding one of said armatures in contact with the outer pole of one of said structures to form an electromagnetic actuator for transferring electromechanical energy to one of said styli.

2. The wire matrix ballistic impact print head as recited in Claim 1 wherein each of said arms further include means for applying a moment of force to said armature causing it to rotate about said outer pole and away from said center pole when said coil is de-energized.

3. The wire matrix ballistic impact print head as recited in Claim 2 wherein said central portion includes a shock absorbing means mounted therein and against which each of said armatures is held by said moments of force when the coil associtated therewith is de-energized.

4. The wire matrix ballistic impact print head as recited in Claim 3 wherein said unitary connector further includes an adjusting means for simultaneously adjusting the air gap between the armature and the center pole of each of said electromagnetic actuators.

5. The wire matrix ballistic impact print head as recited in Claim 2 wherein each of said arms further includes means for holding the stylus engaging ends of each of said armatures in operative alignment with a corresponding one of said styli.

6. The wire matrix ballistic impact print head as recited in Claim 1 wherein said N electromagnetic structures are arranged uniformly around the circumference of a circle.

7. The wire matrix ballistic impact print head as recited in Claim 1 and further comprising a guide means connected to said base for housing said N styli.

8. The wire matrix ballistic impact print head as recited in Claim 1 wherein said base has an aperture and further comprising: a guide connected to said base and extending through said aperture the top end of said guide having N apertures located around the circumference of a circle, and the bottom end of said guide having N apertures located in a straight line; N springs; said N styli each having an enlarged head at one end and passing through one of said springs through one of said apertures in said top end of said guide and through one of said apertures in said bottom end of said guide; wiring means connecting one end of each of said coils in common; and electrical connecting means connected to the other ends of each of said coils and through which each of said coils may be energized; and wherein the N arms radiating from said central portion of said unitary connector hold the associated armature in alignment with one of said heads of said styli and provide a moment of force to the associated armature tending to cause the armature to rotate about the associated outer pole and into engagement with said central portion when the associated coil is de-energized.