US1797237A - Xx x x x x x-x - Google Patents

Description

March 24, 1931. R. H. KRUSE STRING GALVANOMYETER Filed Jan. 6,' '195o /NVE/vToR ArmRNEY indicated at 11?.-and120. `Theinvention may,

PatentediMar, 24, 1931 i I .Y

' steine aanvraag-@METER Application filed January 6', ,Serial No. 418,691.

The presentV invention relates to string gal vanometersy Itis lan object of the present invention to improve vupon string galyanometers, toy the end thatjtheir weightand size may be dei crea'se d,th `e`ir portability enhanced and their f costv "of manufacture'. lessened'. 'Cther and further objects will be explained hereinafter',

and'` will be' particularly pointedf out, in the appended claims.

@ai system.

- string galvanometer embodying the present invention; Fig, 2 isn av sectionV upon the *line -2- 2 of Fig. 1, lool;ing in the direction offthe arrows; Figiffis an enlarged Yiragmen'` taryyiewI ofthe-string member; and Fig lv yis a diagrammatic sectional view of va cammagnet .or'.electromagnet,V shown `O-shaped,` 'i and havingtwo slightlyspaced polel pieces" 16.'y The energizingcoilsgfor the ymagnetiare of; courge, be used also in'other types of gal- `l3`ebruary 19, 1929, the* type* s'liown' inthe only,k '1tl may bey stated, however, that the villustrative galyanometer is of very muchv` smaller size. The trame isxcontinu'ous', or?r I ..O-shaped, providing a double-magnetic rei' j This, with `the ,centrally dis-l turn circuit.

Withtl'ie above' ends inview, a feature' of i l the inyention resides in'u using a conductive f string member that is `rvery thin, except that" 1 v the portion'of the string. member that is dispose/'din thejp'atho the light beam'issuf-f iiciently thick so that V itsosoillationsymay' readily beV observed with the ordinary opti# The;inventili win nwjbe more] 'fuiiy Xs plained in connection with the accompanying drawings, in whichFig. 1 isa View of The pole pieces;

vpermits.;economy weight without proper` tionate loss ofl magnetfstrength.

iinwroan, Assisnon no Tian onMBR-IDGE iN- ,atconcpoitn'rion on NEW "Thefstring `member I5 is suspended inthe electromagneticl` field produced `in the re-.

kstricted air gap kbetween the slightly spaced pole .pieces 16, and` atthe focusv ofthe beam of "lightrays that. proceed from al lamp or other Sou of light 2, through tubes ,22?111761 j v23, J O a light-'sensitive in a ,ph O i' graphm Camera 31 Shownfsutably Positioned in-Fig'lfllj The light fronitl'ie lamp 2 is con; Y

densed by a condenserlsystemand is focused? onV ythe 4 string member by Vay microscope,"y 17,

and "isprojected' to the cameral by fa lens systenfiy 24. Theinagniiication maybe from Q Qto 1,000 `times. In electrocardilography', `i'forV examplait may be 500fti`mes.

The string member 1 5 is shown in EZV as c arriedby-"ia base,:frame'or support '12.

@ne end'fof the' stringm'ember 15 is secured to supportingv head or anchorage 'member 38 andthe other to a supporting head or ailchoragemember), the former being stationyary upon the vframe 12 andthe other adj ust-'- able.` The adjustable head 89 is yieldingly but lirmly held in `adjusted position' byk spring 46. .The` adjustment of the movable head 39 isA eii'ected by means of a yscrew 40 thaltmay b'eturned by a thumb wheel 14. By reason of the various adjustments, andthe positions of the anchorage membersSS and 89' above and-beloy`vthe smallspace between the pole `pieces 16, it is'possible to adjust the ktension of the string membery 15, Lso as tostretch it lengthwiseV oitself between the anchorage members, andto position an inso Y termediate portion o tthefstring member at n the Alproper point inthe saidsmall space,

. l l 'e' z be Vanometers, such las are illustrated, for eig-f transvelsey ,lO-the mlgnetl Hug twee? im? ample, `i'n the above-namedl patent, for :in j

United States Patent No. 1,702,650; grantee@ The string of suchv `a Vga'lva'noineter is fordi- Anznrily constituted of a quartz orf glass thread, -verythinlycoatedvwith gold or other metal drawings' being for' illustrative" 'purposes to render it*condu'ctiVe. The measurements obtained with such instruments depend for Y their accuracy upon the. exceedinglyslight,l sidewise or transverse movement ofthe'elec- 4trof conductiverv string member, in respo'nse to 5 exceedingly 'small changesv in current therein. n

`posed arrangement'l ofthe coils 11 and 20, V`'Notwithstalndingthe'thinnessfof theinetal whole strinO fore, the string member 15 ismadeof evenY less than ordinary thinness, sogas to render 1t as light as possible. So thin a string member .would leave no appreciablertrace or line upon the film-29 ofthe camera 31. The string member is, therefore, slightly thickened, `orV made of larger crossxsection, at an interme-VV 15' diate point 18, where it is disposed between 1 the slightly spaced pole pieces V16. The'extremely thin string member is. easilyactu-k ated by the magnetic field, andthe enlarged or belted portion 'leaves just as effective a shadow upon the sensitive film as though the form thickness throughout.

The length of the vbeltedportion need not be very great.,A A one-millimeter length is suflicientto c'astthe requiredl shadow on the film 29. In practice, however, it is possible` to use longer belts, evenl belts extending Y throughout the full width of the polefaces'.

Thus, a belt one-eighth inch long on a string member ltwo and one-half inches long open.

ates very satisfactorily. So small a belt does not appreciably `change the period of vibration of the unbelted stringA member, noi-its stiffness, so that the string member operates almost exactly the same as though itwere unbelted, and the sensitivity of the resulting" instrument is of the same order as that prevailingin the very much'largerV and more expensive galvanometers. The longer the extent of the enlarged section, the greateris the weight of the resulting strinof member t: Vb b 7 andthe less marked become the advantages described herein. In practice, therefore, it is preferable to have the enlarged section as small as possible, say, of substantially the same length, or but slightly larger than, the width of the beam of light rays at the point where the string member is positioned between the pole pieces. p 'Y V The 4novel string member may be made in many ways, as by bombardment by cathodio sputtering, with shields placed on both sides of the portion of the string member to be belted; ror by condensing organic material on the string from the vapor form; or by'ap.-` plying a lacquer film; orrby dissolving away, on each side of the'belted portion, the coatV ingof an ordinary string member havingits coating throughout its length. A very effective way isv to lower the string member into a drop of electrolyte, and to electroplate on the 4string member a. length equal to the length of the drop. By controlling the length of the drop, it is possible to controlithe length of the belt; and the diameter of thebelt is a function of the current and the time. Vea-.1V

iember were of the same unirecording the shadow produced rious'metals may beused, such as copper and gold c Avery small'Einthoven galvanometer is thus provided, that will give good photo- 'i graphic reproduction, even. on veryV fast, transverse movements of the string member. 'Because of the thinness ofthe string, the galvanometer does not lose in sensitivity, and the belt produces a satisfactory shadow. In-

deed, because of the thinl nature of thestring member, the period of vibration may be yeven higher than in present-day galvanometers.

. Modifications will also occur to persons skilled in the art, and all such areconsidered to fall within the'spirit and scope of the invention, as definedin the appended claims.

` l. In a string galvanometer, an electroconductive string member. having an intering opposed slightly', spaced pole pieces,

and an electro-conductive 'string member stretched-lengthwiselof itself with a portion y'of the string vmember, positioned in the space between the poley pieces transversely'to the path of the magnetic flux between the pole pieces, means forproducing a beam of light. traversing the space between the pole pieces, and means for receiving or recording thev shadow produced by the string 'member in thebeam of light, theportion 'of the string member in the beam ofnlight being of enlarged cross section, and the enlarged cross section being of substantially the same length as the width ofthe beam of light at the point where the string member is positioned between the pole pieces. e l

'4. In a string galvanometer, a magnet having opposed slightly spacedV pole pieces, two anchorage members disposed respectively above and below the space between the pole pieces, an electroconductive string member the ends ofwhieh arecarried by the anchorage members so that the string member is stretched lengthwise of itself between the anchorage members, with `a portion of the Ystring member positioned in the space betwen the pole piecesntransversely to the path. of themagnetic flux between the pole pieces, the said portion of the'string member being of enlarged cross section, means for producing a beam of light traversing the space between the pole pieces, and means for receiving or by the string member in the beam of light.

5. In a string galvanometer, an O-shaped magnet having opposed slightly spaced pole pieces, centrally disposedY energizing coils, two anchorage members,disposedrespectively Y; above andbelow the'space between the pole pieces, an electro-conductive string member Y the ends of which arecarried by theanchorage members l,so that` the'string member is y stretched lengthwise of itself between the anchorage membersgwith a portion of thel string member ositioned Ain fthe space ,be-k tweenthe pole pieces transversely to the path .p ofthe magnetic flux between thepole pieces',k y

the said portion of tliestring memberl being of enlarged cross section, means for producing a beam of light traversing the vspace between the pole pieces, and means for receivingor recording the shadow produced by the A string member in the beam of light.

In testimony whereof, I have Vhereunto subscribed my. name.

. RALPH H. KRUSE.,

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