US2481658A - Electromagnetic operating means for engraving and copying machines - Google Patents

Description

Sept. 13, 1949. a. ca. GRUETTNER 3 9 ELECTROMAGNETIC OPERATING MEANS FOR ENGRAVING AND COPYING MACHINES Filed Jan. 25, 1946 4 Sheets-Sheet 1 1 a j: 61 91 F82 99 102 4 27 21;

x I 84 46 22 10? '1 l I, 0 ll 0 as 88 I a i w v 111 "1 110 V o i::::'::: a]

:0 .0 6 F'" 79 40 J g 81 I 522 l w 75 f 6 10 Sept. 13, 1949.. a. s. GRUETTNER 2,431,653

, ELECTROMAGNETIC OPERATING MEANS FOR ENGRAVING AND COPYING MAQHINES 4 Sheets-Sheet 2 Filed Jan. 25, 1946 Y 1.: ll

IN VEN TOR. Ger/Bald 6. Graettrzw Sept; 13, 1949- ca. 6. GRUETTNER ELECTROMAGNETIC OPERATING MEANS FOR ENGRAVING AND COPYING MACHINES Filed Jan. 25, 1946 4 Sheets-$heet 5 a 6 MM 1 6 Q Q n 6 ||l| Ill-IL 4 0 ,0 n 6 z. T 2 8 a. H a m e a 4 w "N I W w 46 .f/ 4 H a x w L a a ft 8 5 1 m W m .v 4111 m M Q Mr 9 4 2w. A) a y 7 0 7 r 7 J 7 m 6 v I 4 5 7 wm 2 W n 1 v w w 8 w m w w w l'l l a; INVENTOR.

Gen/Bard G. Graetzne/ Sept. 13, 1949- v G. G. GRUETTNER ELECTROMAGNETIC OPERATING MEANS FOR ENGRAVING AND COPYING MACHINES Y 4 Sheets-Sheet 4 Filed Jan. 25, 1946 IN VEN TOR. Gen/1am? 6 Grqq=li71efl to rotatably secure the engraving tool to this pantograph mechanism. In this case, of course,

the means tending to move the engraving tool in" direction away from the workholder have to act not upon the engraving tool directly, but are connected with the support and. tendto turn the same together with the pantograph mechanism and the engraving tool secured to the latter.

Similarly, in case of a machine of this'type the resilient motion transmitting means are con-.

necting the electromagnetic moving means, e. g. the slidable solenoid core not directly with the engraving tool but with the support mentioned 'abovejturnmg the same together with the pantographmecha'nism and the engraving tool toward the work holder whenever the solenoid is energizedr I i I have found that it is advisable to combine {with an electromagnetic moving arrangement of the above described type contact means for operating the electromagnetic moving means which are arranged so as to be closed auto- .matically whenever-the stylus of the engraving machine is ipressed'against the. indicia to be copied. Accordingly, I arrange these contact 'rneans so that ,they are associated with the holding means for holding the stylus and construct jthemso thattl iey are automatically closed whenj'ever'the holdin 'meansare guiding the stylus along the indicia. I provide. also an electrical circuit including these contact means and the electrical moving means mentioned above in such "amanner that said engraving tool is automatically moved toward said work holder by said elec- 't rical moving; means whenever said electrical calQOntactmeaLns are closed, i-e. when said hold- ".ing means are guiding the stylus along the indicia' to b c pie Furthermore, I have also found it advisable to employ as holding means va. holding vsleeve surgrounding. the stylus and arrangedslidably along the same between two positions, namely an operativ'e position. nearer to the indicia to ,be repro .duced, and an inoperative position. farther from .the indicia.

U With a holding sleeve of labove type, I. combine spring means tending to move the sleeve into inoperative position and electrical contact means comprising two contactme'mbers one of which is securedto the sleeve-or a part moving together with the same, and the otherof which is secured ,to the stylus. These contact members have to be arranged and constructed in such a manner that they are in contact with each other when the holding sleeve is in operative position and are spaced from each other when this holding sleeve 'is' in'inoperative position.

The novel features which I consider as characteristic for. my invention are set forth in ;par-

.ticularin. the appended claims. The invention itselfihowever, both'as to-its construction and its method of operation, together with additional'objects and advantages thereofi'willbe best understood from the following description of specific "accompanying drawings, in which:

"embodiments when read-in connection with th'e Fig. 1 is a side view of an engraving machine according to my present invention in inoperative position, seen in direction of arrow l on Fig.

2, with part of the side wall of the base removed; Fig. 2 is a top View of the engraving machine ShOWI1 "illiFigf-LLSEGII Fig.1; .571.

Fig. 3 is a cross section the stylus, the

holding sleeve and electrical contact arrangement connectedwith the same along line 3-3 on 'Fig'.' 4 'is' thefelectrical circuit including the electrical contact arrangement shown in Fig. 3 and the electromagnetic operating means shown in Fig.1;

Fig. 5 is aside view of the engraving machine shown in Figs land 2 in operative position; and

Fig. 6 is a. bottom view of my new engraving machine, seen in direction of arrow 6 on Fig. 1.

As shown in the drawings, my new engraving machine comprises as main elements a base: I 0,

two supportingbrackets H and l2'firmly mounted on"v this base,'.a'turnable horizontalshaft l3 pivoted to brackets II and I2. a supporting member 14 secured to this horizontalshaft l3 by means-of lugs l 5 and I 6. and .turnableup and down together with this shaft; about its-horizontalaxisin direction of arrow l1, a'pantograph mechanism [8 of known type pivoted; by means of pivot sleeve jl9.:to. thecsubstantially: vertical pivot 20 secured to support ;l,4 insuchsagmanher; that the p'an-tograph mechanism is movable about this-pivot '20; in horizontalplane as. indicated by arrow 2|,and an engraving tool: 22 'arrangedalso at least substantially v'erticallyahd secured to the pantogr'aphmechanisml8. in the specific.mannerldescribed belowindetail.

As shown'in the-'drawings,iI arrange underlthe engraving tool. a;work holder 23 which might be scribed andclaimed in inyiico-ipen'ding 'U.; .S.

'patent applicatidn-SerialNoi 592,875, filediMay 9,

I945, and nowltabandonediand' entitled ..Work piece-holders. I The. .panto'graph mechanism of my new machine-:consist as usual .offour. panto'graph : members 24, 25, 26 and ZIturnably connected-fiat,

29,30 and 3] so as to form'a' parallelogram. The :pantographmember 26 extendsxat32 beyond the pantograph member. 25 and serves-as support for the engraving tool .22. The? pantograph member 21 extends at 33:also "beyond: thepantograph member 25 and is turnably connected at 34 toga stylus v35 adaptedto'followthe outline of them- "dicia" 36 firmly supported by: an indi'ciarholder 31 which does?not;formipart of my present .in-

- ventioni' however,- I wishtonote that I'prefer to a use in combination with my .present'invention an indicia holder of the type described'and claimed in my .co-p'ending patent application-Serial No. 592,876, filed May 9, 1945, and entitled Indiciaholders!"- In order to prevent undesired contact between and nowiabandoned,

the engraving tool T 22 and the work piece supf ported'by work-holder-23 it. is necessary to'move. the engraving 'tool betweenfengravingi periods into inoperative position out of contact. with. the workpiece;- Forthis purpose, an arm'38 islpr'ovided on lug l5 of support [4 and a sprin'g 39 is securedat its one enc' to the lowe'r end 40 of arm 38 and=at its-"other en'd' -t'o 'a projectitigpart H of r'direction -of arrow 2 on -nbase: l; thisuspring .permanentlyatends; to pull .:;arm 38 indirectionof. arrow.

42,..thereby tendin etc turn the; entireilsupport .14 indirection ,of

arrow 43.. causing. .the :engravin tool 22 to be forced in direction of. arrow.

work piece. supported by the workpiece holder 23.

, The .engravingtool 22- comprises. an outer supmportingsleeVe.member 45 provided at its lower ,..end with a conical;

portionl46 thetip 41 of which iE srl-rsand 5, thecore 1- with'the arm 38; secured togthe 'tiltable, support. [4.

I have found that in, casesuch anelectromag- Qnetic arrangement, particularly if a solenoid,- ar- 441away from the g same is connected with current, it is of great rangement, is, used and the an alternating source of importance thatthe core 11 be drawn entirely serves for guiding the;engraving-;tool-,on the worko lo apiece; to be engraved. T his supporting sleeve member 45 rotatably supports aholder 48 which .is of tubular shape andholds theengraving mneedle49 which .is used for. actual engraving of ithezwork piece. w 1 In order to rotate the needle withthe necessary cspeed, a pulley 59.is providedatthetopof the r same; a corresponding pulley 1 to :shaft 6I,of..the electric. motor 62,; this motor,

rotatable tool holder 48 firmly secured tov the 60 is. firmly secured 1.62 ispivoted at 63 turnably about a vertical axis .to bracket 64 secured to and forming part of base Ill. The driving belt ,-60 -.transmits.the rotating movement. of shaft 6| to tool holder 48 and the engraving needle held 'circuit of motor 62-, .the drawings, serves for starting and. stopping op- 65 engaging pulleys 59 and Switch 66 inserted in the electric which circuit is not shown in 'by .the same.

1 eration of the motor.

Asmentioned above, ed to bracket 54; this enables the motor to follow the movement of thepantograph mechanism durin the engravingoperation; however, despite necessary tokeep the driving undertension. This tension is obtained bymeans other end H3 to bracket I .pin 6'! in direction of arrow 1! resulting in a Such following movement of the motor, it is also of pin 61. secured ,to secured at its one end the .motor and spring 68 69 to. this pin bland at its 2 and tending to turn tendency of motor 62 to turn indirection of arrow 12. This keeps the driving belt 65 under-permanent tension.

.machine of the above described type in the usual, 45 qway, i. e. by pressing the pantographmechanism" ward in direction of arrowr 'l5.

It is, of course, possible to operate an engraving l8and thesupport l4 by means of button 14 down- This manual downward-pressing movement is. continued until the point of the engraving needle 49 contacts the 'xwork piece 23. It is evident that for such manual the stylus alon hand for carrying out theabovementioned down- -1ward-pressing movement of theengraving needle operationof the engraving machine both hands are needed, i. e. onehand for holding and moving the indicia 35 and the. other j 49. Of course, such operation of the machine is .not only rather diflicult and cumbersome, but also necessitates accurate synchronization between the two movementa'i. e..between the following movement carried out by stylus 35 and the pressing down movement of the engraving needle 49.

In order to avoid such complicated operation of "the engraving machine, I provide in, accordance with my present invention electrical means for automatically. moving the engraving needle 49 into This electricalarrangement according to: my

-. present invention comprises. as :mainelements. a

solenoid l6 of-well-known type built in;;such.a

manner as topullzthe zcorez1:1;irr.;directi0n.of

narrow-'18 whenever it is. energized, and the 'conatheoperative position of arm 38 into the solenoid .ifiwhen the same is energized. If this is not the case, a relatively great currentis necessary to obtain the necessary force. I

However, as well-known, the work pieces i3,to be engraved are of different size and therefore depends on the size of the work pieces. Accordingly, if instead of the two rods 19 and 80 only one connecting rod would be used, the final operative position of core l1 :would be different for different work pieces, 1. e. it wouldproject to different degrees beyond the open end of solenoid l6 and would not-be drawn entirely within the same.

In order to: avoid: such different positions of the .core I! inoperative position and to enable the core to be drawn entirely within solenoid lb-when the same is energized independently from the final operative position of arm'38, I provide a slidable spring connectionbetween the rod 19 and the motor 52 is turnably pivotrod 80. a

This spring connection consists, as clearly shown in the drawings, particularly Figs. 1 and 5, of a sprin 8! held by pin 82 secured :to rod 19 and pin is secured to rod 80 in the position shown in the drawings.

This spring 8| tends to move pins 32 and 83 away fromeach other and is thus adapted to transmit motion impulses from rod 19 belt 65 permanentl to rod all; It is evident that by use of a spring arrangement of this type it is possible totransmit motion impulses from solenoid l3 to-arm-58 --in such a manner that the core 11 is in operative position always drawn entirely within solenoid I6.

Of course, depending upon the operative position of arm 38, the distance-between pins 82' and 83 will vary.

'As clearly shown in Fig. 4, the electrical circuit 84-comprises not only the'solenoid 16, but also the general switch 65 connecting this circuit 84 with thesource of electric current 85, and the contact arrangement 86 described below in detail.

The contact arrangement 86 serves for energizing solenoid 16 and comprises as main'elements the slidable holding sleeve 51 surrounding the follower needle 88 forming part of stylus 35. This follower needless is firmly secured to the stylus arm 89 forming also part of stylus 35; this stylus arm is pivoted as described above by pivoting'means 34 to the pantograph mechanism 18. The follower needle 83 is provided as usual with a screw threading 9B and knob SI for adjusting the length of'this needle. For the sake of the record, it should be noted that knob 9| never serves for holding the stylus 35 during operation,

but serves always-exclusively only for adjusting the'length of. needle 88. The stylus 35 is'guided during engraving always by gripping the follower needle 88 below arm 89.

" The slidable holding sleeve 8'! is not secured to the follower needle 88 but freely slidable alongthe same. It is attached" to the stylus arm 89 by means of spring 92 which is firmly secured at its one end 93' to the top 94 of sleeve 8'! and atits other end 95 by thesmall screws 95 to arm '89. This spring attachment enables sliding movement of-the sleeve 81 along the follower needle 88.

In the embodiment shown, afpin 91 is secured to spring 92." 1This-pinpassesthrough.holest in *a'rm89and is, at its-other; end connected tojthe -isnect'ing.10411519531163 8osconnecting gas show-n in contactspring 99 "carryingthe contact mernber shown. Both these contact members I and IN are connected by means of electric wires I02 and 103, respectively, with the electric circuit 84 shown in Fig. 4.

Since closing of switch 65 not only connects the solenoid arrangement described above with the source of electric current 85 but also causes rotation of motor 62, I provide a plug I04 arranged as shown in Figs. 1, 4 and 5. Of course, I might use instead of this plug I04 connecting the contact. means with the circuit 84 also a second switch similar to switch 66.

My above described engraving machine operates as follows: I "First the indicia 36 are placed upon and secured to the indicia holder 31 and work piece 13 indicated in the drawing in dotted lines is firmly secured to the work holder 23. Of course, it is necessary to adjust the work holder in such a manner that when stylus 35 is in contact with the indicia 36 to be copied, the work holder 23 and the work piece13'held by the same are in proper position for engraving under the engraving needle 49. I'have-found it advisable in order to avoid too great a distance between the engraving needle 49 in inoperative position; a shown in Fig. 1, and the operative position, as shown in Fig. 5, to provide means for adjusting the inoperative position of the engraving needle 49 and of the support I4 holding the same. These adjusting means consist, as shown'in the drawings, of an eccentric cam I 05 turnably pivoted at I06 to the bracket I I. An adjusting lever I01 enables turning of the cam I05 about its pivoting point I06. This cam I05 is arranged so that in its initial inoperative position'arm 38'abuts against it as shown in Fig.1.

Thus, it is evident that by adjusting the position of cam I05 by means of the adjusting lever 101,

- the initial inoperative position-of arm 38 and support 14 secured thereto can be adjusted.

After these preliminary steps the switch 66 is closed, starting rotation of motor 62'which, in turn, rotates the engraving needle 49. a

In order to start engraving, the holding sleeve 81 surrounding the follower needle 88 of stylus 35 is gripped by the operator and guided in such a manner as to press the tip of the follower needle 88 against the indicia 36 to be copied. It is evident that during pressing of the needle 88 against the indicia by means of the slidable holding member 81, this holding member will be moved downward along needle 88 in direction of arrow I08 from its inoperatve position shown in Fig. 1 into its operative position shown in Fig. 5. Such downward movement of the holding sleeve 01 will result in contact of the contact members I00 and IM and in closing of the circuit 84. This in turn will result in energization of solenoid 10 and movement of the solenoid core 11 in direction of arrow 18 from its inoperative position shown in Fig. 1 into its operative position shown in Fig: 5. Such movement of the solenoid core will havea pushing effect upon arm 38 forcing the same together with support I4 and engraving needle-49 into the operative position shown in Fig. 5.

It should be stressed that this effect is obtained without exerting any pressure by hand against the top of the engraving needle 49, i. e; fully automatically, simply by holding the follower needle 88 by means of sleeve 81 and pressing it against the indicia to be copied.

It is evident that wheneverthe follower needle 88 .is lifted by meansof sleeve 81 from the indicia, the contact members I00; and JOI be- 51-8 F "come dlsen ga'g'e'dand the solenoid "16 is 'de'ene'rf 'gized thereby enabling spring'39 to move arm 38 together with support [4 and the engravingnee- I mess from its operative position shown in Fig. 5 :jfb'ack into inoperative position shown in Fig. 1.

It will be understood that each of the elements "described above, or two ormore together, may {also find a useful application in-other types'of eng'raving and copying machines differing from IU-the types described above.

j While I have illustrated and described the invention as embbdied in engraving and copying machines provided with turnably supportedpam tagraph mechanisms'I do' not intend to be'limited to the details shown, since various modifications and structural changes may be made itliout departing in any way from the spirit "of myinvention. i Thus forinstance, I might combine with'an 20'eng raving machine of the type proposed by me a f pneumatic braking device I I0 secured'to'base- I0 and connected byplunger rod! with arm 38.

, in such a manner as to brake the speed of turning of this arm from its inoperative into its operative position, while exerting no braking ef- 7 feet during movementof this arm back from its operative into its inoperative position. Such braking means prevent the engraving needle 49 from hitting the work piece 13 with too great a 80 force thus avoiding damage to the needle or the work piece to be engraved.

Without further analysis, the foregoing will so fully reveal the. gistof my inve'ntionthat others can, by applying current knowledge, readily 85 adapt it for various applications without omit-'- ting features that; from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and therefore such adaptations should and are ing and range of equivalence of the following claims.

What I claim as new and desire to secure by ilietters Patent isi V 7 '45 1 1. In an engraving or copying machine for reproducing indicia, a base; 'a support turnably attached to said base a movable pantograph mechanism turnably pivoted to said support; an'engraving tool rotatablysecured to said panto 50 graph mechanism; a work holder secured to said base and located at least substantially under said engraving tool; means mounted on said base tending to move said engraving tool in direction away from said work holder; electromagnetic .55 moving means'mounted on said'base; resilient motion transmitting means resiliently connecting said electromagnetic moving means with said turnable support and adapted to turn said support together with said pantograph mechanism ml and said engraving tool rotatably secured tothe same toward said work holder secured to said base; means secured to said basefor'holding said v indicia to be reproduced; a stylus for following saidindicia attached to said pantograph mechanism; electric switch ;means mounted on said' 7 Stylus; andan electric circuit including said electromagneticmoving means, said electric switch 'means and a source of electric current so as to enable operation of said electromagnetic moving means and movement of said tool holder by means of said resilient motion transmitting means toward said work holder each time'said electric switch means are" closed.

' 1.v 2.-In an engraving or copying machine formproducing indicia, a: base; a support turnably atintended to be comprehended within the mean- -I-itachedd:o:=saidbase;:a movablerpantograph mechanismrturnably: pivotediatorsaidzsupport; an engraving tool rotatably secured to saidpantograph mechanism ;--iaiworkfjholder :secured to said base and located at least substantially under said en- '7';

iiently sconnectingisaidmotion transmitting mem- 4 bers and adapted to resiliently transmit motion impulses from said first motion transmitting member to said second motion transmitting member so as to turn said support together with said pantograph mechanism and said engraving tool by means of said second motion transmitting member toward said work holder whenever said first motion transmitting member is moved by said electromagnetic moving means; means secured to said base for holding said indicia to be reproduced; a stylus for following said indicia attached to said pantograph mechanism; electric switch means mounted on said stylus; and an electric circuit including said electromagnetic moving means, said electric switch means and a source of electric current so as to enable operation of said electromagnetic moving means and movement of said tool holder by means of said motion transmitting members and said resilient motion transmitting means connecting said members toward said work holder each time said electric switch means are closed.

3. In an engraving or copying machine for reproducing indicia, a base; a support turnably attached to said base; a movable pantograph mechanism turnably pivoted to said support; an engraving tool rotatably secured to said pantograph mechanism; a work holder secured to said base and located at least substantially under said engraving tool; means mounted on said base tend ing to move said engraving tool in direction away from said work holder; an electromagnetic solenoid arrangement mounted on said base; a slidable solenoid core forming part of said electromagnetic solenoid arrangement and constructed so as to be drawn into said electromagnetic solenoid arrangement each time the same is energized; resilient motion transmitting means resiliently connecting said slidable solenoid core with said turnable support and adapted to turn said support together with said pantograph mechanism and said engraving tool secured to the same toward said work holder secured to said base each time said slidable solenoid core is drawn into said electromagnetic solenoid arrangement by energization of the same; means secured to said base for holding said indicia to be reproduced; a stylus for following said indicia attached to said pantograph mechanism; electric switch means mounted on said stylus; and an electric circuit including said electromagnetic solenoid arrangement, said electric switch means and a source of alternating electric current so as to enable energization of said electromagnetic solenoid arrangement and turning movement of said turnablesupport together with said panto- .-graph (mechanism and engraving tool toward said-workholderieach-time said electric switch means areiclosed. x

4.;In-anengraving1or copying machine for reproducing i'n'dicia', aibase; a-suppcrtturnably attached to said base; a movable pantograph m'echanismturnably'pivoted to said support; an engraving tool; rotatably secured-to saidvpantograph'mechanism; arwork holder secured toxsaid .base and located: at 'leastsubstantially under said 'engraving' tool; :means "mounted on said .base tending to"move-i;said engraving toolinsdirecltion away from: said .work holder; an electromagnetic solenoid arrangementmounted on said basepa slidablesolenoidcoreiforming part of said electromagnetic .c solenoid arrangement and constructed soias tobedrawn' into said electromagnetic solenoidxarrangement each time the same isenergized ;tr a: first :motion transmitting member connected with said slidable solenoid core in such a manner as to be moved by the same whenever said slidable solenoid core is drawn into said electromagnetic solenoid arrangement: a seco d motion transmitting member connected with said turnable sup ort and adapted to turn the same together with said pantograph mechanism and said engraving tool secured to the same toward said work holder secured to said ba e: resilient motion transmitting means resiliently connecting said motion transmitting members and adapted to resiliently transmit motion impulses from said first motion transmitting member to said second motion transmittin member so as to turn said turnable sup ort together with said pantograph mechanism and said en raving tool by means of said second motion transmitting member toward said work holder each time said first motion transmitting member is moved by said slidable solenoid core; means secured to said base for holding said indicia to be reproduced; a stylus for following said indicia attached to said panto raph mechanism; electric switch means mounted on said stylus; and an electric circuit including said electromagnetic solenoid arrangement, said electric switch means and a source of alternating electric current so as to enable energization of said electromagnetic solenoid arrangement and turning movement of said turnable support together with said pantograph mechanism and engraving tool toward said work holder each time said electric switch means are closed.

5. In an engraving or copying machine for reproducing indicia, a base; a support turnably attached to said base; a movable pantograph mechanism turnably pivoted to said sun-port; an engraving tool rotatably secured to said pantograph mechanism; a work holder secured to said base and located at least substantially under said engraving tool; means mounted on said base tending to move said engraving tool in direction away from said work holder; an electromagnetic solenoid arrangement mounted on said base; a slidable solenoid core forming part of said electromagnetic solenoid arrangement and constructed so as to be drawn into said electromagnetic solenoid arrangement each time the same is energized; a first motion transmitting member connected with said slidable solenoid core in such a manner as to be moved by the same whenever said slidable solenoid core is drawn into said electromagnetic solenoid arrangement; a second motion transmitting member connected with said turnable support and adapted to turn the'same" together with said pantog'raph'mecha= {member and at its'other end to said second motion transmittingmember and adapted to resiliently transmit motion impulses'fromsaid "first motion transmitting'm'einber to said secondmotion transmitting member so as to'turn said turnable support together with said g'aantog'rap'h mechanism and said engraving t'oolby means of said second motion transmitting member toward said work holder 'each time said first motion transmitting member is moved by said slidable solenoid core'; means secured to said base for holding, said indicia to be reproduced; a stylus ior followingsaid indiciaattached to said pantograph mechanism; electric switch means mount- ;ed on said stylus; and an electric circuit includ- '12 ing said electromagnetic solenoid arrangement, said electric switch means and a'source o1: alter= mating electric current." GERHARD G. GRUET'I'NER.

REFERENCES CITED The following references are of record in the file of this patent; V

UNITED STATES PATENTS Number Name Date 548,484 Wallen Oct. 22, 1895 671,174 Albee Apr. 2, 1901 938,936 Ziegler Nov. 2, 1909 2,199,261 Kapp Apr. 30, 1940 v 2,241,794 Still! May 13, 1941 FOREIGN PATENTS Number Country Date' 7 281,777 Great Britain Dec. 12, 1927

Images