US2455913A

US2455913A - Stylus construction

Info

Publication number: US2455913A
Application number: US558799A
Authority: US
Inventors: Benjamin B Bauer
Original assignee: Shure Brothers Inc
Current assignee: Shure Inc
Priority date: 1944-10-16
Filing date: 1944-10-16
Publication date: 1948-12-14
Anticipated expiration: 1965-12-14

Description

uNn' o STA This invention relates to a stylus" construction been had to "so -called scratch filters. Such filters,

.. the mechanically generated type.

shock and. abuse.

.ness with substantial vertical compliance.

terms lateral and vertical refer to the normal playing position'with a pick-up riding on top of a substantially horizontal fiat record. The lateral rigidity involves rigidity substantially Patented Dec. 14, 1948 :11 I

STYLUS CONS TRI IC'IION IX Benjamin B. Bauer,- Oak Park-"11L, assignor; by"v mesne assignments, to Shure Brothers Incorpo rated, Chicago, 111;, a corporationof Illinois Application October 16, 1945;, a Ndfsstase foruse in phonographreproducersand picktl'lps- '-The stylus construction of this invention is par- ;ticularly adapted for use with reproducers'operating on records having a laterally sinuous'sound groove: I p

In reproducing froin records having such a laterally sinuous sound groove, there is customarilypresent so-ca lled record noise or scratch This is generally present in' new records and increases with use. Such record scratch exhibits a continuous or band spectrum over a substantial frequency range, but'usuallyhas a substantial part of its energy in frequencies above 300d cycles per second. The precise energy spectrum depends upon the recordmaterial, reproducerand other factors.

In order to eliminate'record noise or scratch in the case of electrical pick-ups, recourse has usually an electrical flow-pass system, operate .upon the pick-up output to eliminate frequenci'es in the so-calledscratch band. Asa rule such filters are adapted-to eliminate -frequencies above about 3500 cycles'per second as a, com- "p romisebetween scratch elimination -and fidelity of reproduction. Itisevident that reproduction is impaired' and the higher frequencies; characteristic of individual instruments and voices, are entirely lost;

It has been determined that scratchin-an 'electrical pick-up not only 4 involves a anelectrical "scratch output at the pick-up terminals but I also includes generation of audible noise-at the region of stylus vibration. Apparently mechan--- .ical vibration incident to reproducer'operation generates noise-which is partly generated", by record vibration and partly by stylus and repro- 1ducer vibration and reflected from ;surface. I

,-.-The invention herein provides a stylus 'con- ;struction which provides reproduction'from northe record mal sound tracks ina record-but is remarkably free from reproduction of scratch particularly In addition .thereto,the invention provides .a construction which protects the record against mechanical Ithas long been known that desirablestylus characteristics demand substantial lateral stifi-- The 11 Claims. (Cl; 274 -38) I -tures have not been 'satisf-actory'for the-"reason that a high vertical compliance was inconsistent to a large degree with lat'eral rigidity; The two along a the perpendicular to a'sound track 1. e.

af -lin substantially parallel to a record radius at the stylus tip. "Thevertical compliance refers to compliance alo'ng a, vertical line substantially perpendicular' 'to the record'at the stylus tip. Thus by having lateral stylus rigidity, vibrations generatedat'the stylus tip infollowing a sound track are faithfully transinitted' to the-reproducerjproperJ On the other hand, any sudden stylus movements along a vertical line-are sub stantially attenuated' -prior to reaching the re- "producer proper. Gradual stylus movementsto accommodate record'unev'enness due to warping for" example are transmitted to therepro- *duce'r proper so-that floating r at a constant stylus pressuremay; be effected. v I

"Prior" art constructions "have been undesirable 'ior various reasons. Thus mechanical-simplicity and efficiency are-essential.- Complicated mechanical structure's usually have a complex responseto' vibrations, particularly when the range of frequencies'is extended. 'f Such structures 1 are" difiicult to manufacture in' quantity and tend to change their response characteristics as parts ageor 'arest'ressed.- -The more simple struchave been dependents in prior art structures with the actualdesign having a' compromise, By virtue of the inventionherein, the mutual dependence of vertical compliance and lateral rigidity has been largely-"eliminated.

The invention achieves the'above withoutsacrificing mechanical simplicity. By virtue of the invention, a structure embodying th invention is'en'dowed with highlydesir'able mechanical characteristics'and greatruggedness. Thus the inprovided. "For vertical stylus vibration, howvention "provides; 'a "structure Within which a delicate interplay of forces maytake place during normal'u'se but which is protected against shock and rough usage. The resulting'structure thus is capable of substantially scratchless record reever, apath having great compliance is presented.

By virtue of'ithe mechanical structure near the stylus "point, advantage of vertical compliance is 'take'n to endow "the structure with shock pro- ..invention.

.an end. portion .2 l.

tection. In addition, the parts are so shaped and disposed with relation to each other that undesirable moments are efiectively eliminated. It is also possible to obtain great vertical compliance without utilizing relatively weak and fragile parts.

In another aspect, the invention generally provides a spring between the stylus tip rand reproducer proper. Between the spring and stylus tip, there is provided shock absorbing means, which function by virtue of the vertical spring compliance. sive vertical loading is efiectively prevented.

For a further description wof the invention, reference will now be made to'the :drawings wherein Figure 1 is an elevation showing the invention in use in a pick-up. .Figurelis afront elevation partly in section of the needle'struc- Side view similar .to .Figure 3 but showing the position assumed bythe construction when subjected to excessive vertical loading. Figure is a :side elevation of a modified .form of the Referring to Figures 1-4 inclusive, tone arm H] may be provided witha suitable stylus clamping means such as screw II for retaininga stylusin predetermined fixed position for reproduction.

The tone armand reproducer may be of any desired construction and since theyarenot part of the invention will not be shown or described in detail. The reproducer may either be of the mechanical-type or may be apick-up adaptedto translate mechanical -vibrations' directly or indirectly into electrical waves. .As shown, :the stylus consists of shank l2 havinglflattenedtpor- -tion I3 adapted to be engaged byclamping means l I. for firm retention. Shank llmay be made of any suitable material such as steel,:alu.minum, or any-- other elastic material and-asshown here :has a portion thereof shapedto form ailateral stub l5.

.StublE may be downwardly-bent at any desired angle away from the axis ofshank lland as shown is bentat anangle somewhat less than -90- degrees. 'Stub l'5 terminates vimknob-or head portionlfi to which may be rigidly attachedwa .spring truss generally designated as I1.

Since the shank is generally inclined .as shown, 'adueto .conventiona1 reproducer design,:.and since-it-is desirable to incline spring'trussl'laway from vertical to utilizeits compliance, the addition of vstub I5 is beneficial.

The structure designated byinumeraldl is an open truss-like structure which-mayadvantageously taper in width from a small width at: the .stylus end to a maximum width .at the upper shank end. This is not essential but'does endow the structure with desirable mechanical properties. As shown here, truss-like structure 11 is in the form of a spring leaf andmay be fastened to head 16 in any desired manner. Thus'the spring may be suitably .apertured to permit threading on stub l5 and the metal .of head 16 may .be rolled or peaned overto maintain the same firmly in position. Spring l1.may be made of spring steel, beryllium copper, phosphor bronze or other elastic material and,.as'shown. in Figure 2, is generally tapering with the "wide portion adjacent head [6. Spring I! has two arms l8and l9 whose ends are rigidly coupled at head t6 and End portion-2| is shaped-to form agenerally Vspring heelg-having portions Thus damage to record grooves by exces- 22 and 23 with a fold section 24 as the V tip. fhe entire V portion is bent down from truss-like structure I! as seen in Figures 3 and 4. Part 23 of the V is provided with a stylus point 25 which 5 may be of any suitable material such as steel, carboloy, osmium, a jewel, or the like. Stylus point 25 may be mounted in part 23 in any desired iashion; :If desired tlieg heelrzmay simply .be. fastened to spring ITxnear .the lowercend with the spring extending continuously beyond it. It -.is clear that the heel is rearwardly of the stylus tipas seen from the front of the tone arm.

As evident from Figure 3, V portions 22 and tza-areso disposed with respect to each other and -5 with-respect to-truss-like structure H that point 25,.particularlyztip 26 thereof, substantially lies .on the prolongation. of the axis of shank l2. Furthermore; the spring structure and stylus tip ..are-so proportioned that tip 26 is substantially in the plane determined by truss-like structure .11.. .In' other .words, it is preferred to.-so proportion and dispose the various parts ofthestructure below. shank-l 2 that the prolongation -of=the axis of shank. l2 pwil1v intersect the plane of. truss-like :structur e l'!' substantiallyatthe stylus atip. :It is understood that the above relationshipiis true ..when the normal loadison thestylus-tip. The truss-like structure is ordinarily .bowed as: shown in dottedlinesin Figure 3 whenthe stylusis free 330 :-Of. all loading. Hence when. normal vertical loadv.ingis applied, truss-like structure I! becomes straight. T

The .truss-like structure may be for-med of spring wire "with. the ends rigidly coupled to .the

;, .shankandend portion 21. .If desired, asolid leaf .spring may .be :used.

It is clear that lateral rigidity will bepresent ,solongasthe arms do not buckle under com- ..pressive-forces. In order to provide additional .340 support to-the truss-likestructure itis preferred todispose a .pad 20 betweentheearms. This pad ispreferably of material like Viscoloidfrubber, .-leather or the liken-having.substantial vibration damping properties. -While the pad .shape may 5 vary, itis preferred to-provide-"a pad filling .the ..entire open space between the arms. Theqpad may beiorced into position and since itis thicker than thetruss-like structure, it will 'rretain itself in. place. I Preferably pad 20 extends not only'zthe full length of truss-like structureul'lnbut bridges ..the .V heelporticn to abut against stylus tip'25. Thus pad 20- tends to stiffen the entire structure and ,provideszdamping .in both lateral and vertical "directions.

Vertical damping is clearlydesirable andtends .to suppress scratch vibrations. LateraL-damping ..is so designed .as todmprove the 'vibrationtransmission characteristics'of the truss-"like structure and flatten out: any resonance peaks "which may 50 be present. The damping in two planesten'dsto ..suppress any complex modes of'vibration ..and ..restricts the. truss to simplemodes oflvibration "in .lateral-andvertical directions. I

The entire stylus constructionrmay be mounted in any desiredfmanner. However; for ease of manipulation in setting the pick-up in playing posiition andiease ofitracking, it is'preferred to dispose the stylus construction as shown. *Thus the'plane generally: determined 'by'truss-like structure I! HIOmay .be:.inclined to the record to form an acute angle in the" direction of record travel. It is pre- 1 ferred to'have thegeneral plane'of the truss-like structure intersectithe record in a line. generally .paral1el:to:a line passing through the stylus point and -;.perpendicular to t the sound --track. Then tiom components. The various; parts i are/ so pros-'- Iiortioned: and disposedszthatstylus i'tipi 26,;under' normalrplay-ing conditions,=. is substantially :collin ear :withthershank: axis andin-the generaLplane;

of; truss-like: structure- H; This collinear relationship-isof substantial importance Thus lat:

eralrstyluswtipvrnovements create shank bending; movements;- This is theudesiredmodexofi op.er--t azticn ,No torsional moments on the shank: are: created since the force on the stylus: tipg'is-ap-e plied. on; the: shank axis.- 1 The; reproducerdoes which .-it iisnnot normally designed? torreceiver,

tures sthe'resilient portions. have been; comparae tively short. Tl'ius-unless-weak springswere used;- compliance was low, 'Any-increase in spring;

len-gth. would, generally-interfere with proper.

pick.- up.- operation. I-Iere however, the-length of:

truss-like structure I1 is independent-of proper: piclr u-pa operation. general-plane of the truss-like structureqintersect at thetstylus tip, length of-vthe truss-likestructure.

will not affect transmission of later; stylus vibrae' tions. However, along trusslike structure per-- mits greater compliance for undesired. vertical vibrations Without using objectionablythin truss material.

In normaL foperation; components;normally tendingrtol'generate record scratch and vibrate the. stylus-tip generally vertically to the record wilLbeattonuated because ofyertical flexibility ofltru'ss' 1.11. Onthe other hand; lateral reproducing stylusmovements will be transmitted by the lateral rigidityof the trussrlike structure to. the shankproper. f V

"The .r heel structure asnparts 22 and: 23 so dimensioned with regard to physical'leng'th, lw'idtl'rv and thickness .thatunder norm-a1 playing condi-w tions', such as shown in Figure 3, fold 24lisi disposed ,a short distance above record 212111 the rearof the stylus tip. Fold 24 ispro ferably curved sonofedge will'znar therecord'. Thus, i'f'the stylus, Happens: to he overloaded) as during dropping;v

Since the .shank axis; and

, connection. with Figure: 4..

' Referringimow toffiig'urefieaamodifiedistructure iSi-ShOWHr wherein the pickeup generally? is WIDE- 1 videdtwith,,astorsionrrod v1|lkwhoseaxis isrgenerailyu parallel-twine:plane' ofrrecord 211.; Arraexamplez on. a'zpiclwip ofethis character: isidisclosed ;invPa-t-I' ent;- 2',-326;280r.v issued x. August 10-, 1943. Torsion. rocl 3 flemayehavevas suitable: clamping. screw 31:2 extending in-ton the sameefrom; the. bottomvfac ,w Clamping screwi- 3il 'rigidly maintains; a: springs: truss structure: or the same.- general-constructiom assshownt i-li'li Figurese 12-4: inclusive 'lihee truss? like structure: mayw bee retained l place by .a;' clamping, endlportionw32 engaged by screw 35'! In thisimodifiedi construction stylusf tip 2-6 is l normal -lye in the: genera-l1; plane of; spring trussslilreq ru u e;- e l Y It is clear;- that-ether stylus: construction: acts-in: precisely the same mannerassimFigures, elusive; In thel-preceding figures the: alignment of.-sty;lus=.-tip;and shank axisprevented. the-genera ation of torsional:moments-onltheshanks. Hence& the shank wastgenerailyt'subi (acted. to; transverse momentst-tending'tc; bend. it-.. Itse-stifiness is-amples to transmit-such bending, momentseto the; reprcv ducen proper-h In the; construction; ofhFiguretr.5

the-Jshankris entirlywliiriinated. Howevervthe:

forcestrfromt the. truss-alike structure: are "in; the;

same direction as in thelpreviousconstruction.

In. the eyentrthat truss-like structure I! ;is replacediby alsoli dhiiatspring it-.issclear:thatlthe parts. vszi l l, liave..tol loeeproperly proportioned to obtain-- the; shock-absorbing}: action. des.cribed--. in v In such case; the-- spring rnayn be, elongated; to promote flexibility; Byvirtue. .of thei invention ahighly desirable;

; stylusconstruction-As:provided. In use; thereon-5 structionA-protects bothethe'usuall-y fragile stylus? tip; and ffinetrecord 2 grooves; against seriousflam age I .1 Thee usual scratches; across. a: number; or} record ,grooves; resulting; from: careless handling: willrbe, generally; eliminated; Im addition: to all; this, reproduction; is effected .-at substantially no; reduction-inseificiency: r

,While: the stylus construction :=has beemzdisl-u closedias genera-11y)" inclined in: the: dii-YBCtlQIIL'OfA and moved across, record I grooves at the saine time; ia smooth surface will slide over the record and"noidarnagetosound grooves willb-e possible." The'el'asticity'of theftruss material together with the" dimensioning of thejvarious" portions fof" the truss-like" structure "and dissipation insert are such as to provide a'shocl; absorbingaction; [Ihus i'rrtl'ie eventofexcessive yertical' loading as when theenti 're' pick-up structure is; dropped onfstylusi 25;fiexureof truss-like" structure"l1 will result.

' It is evident that the entire truss like'structure' willbe flexed" inthe 'manner shown in; Figure 4; ilfer to bow the truss -like structure generallyt'o wardt'he record: The insert of dissipationmaterial has" sumcient: flexibility so itwilljbend also. 'Ilrllisfiexure of" the truss-likestructure will dopress'fold 24 so that it engagesrecord Z 'Ior' what.-

ever is hit; Stylus 25 willbe swungupwardly to clear record By propoitioningthew length of: trusslilie s'trlu'cture' ll," therelatiye width of van-- reversed if so desired; v

,What-:iszclaimedzisr w 1: Inc: a: phonograph reproducen: having"; ar'vi brata'ble; membenz-a; stylusaconstructiorr in ch'idinga lgenerally fiair's'pring;:morma'lly extending; from: said:reproducendownwardly toward: a; record, said spring. having: it'smppen" end: coupledf to said vi recordrtravelgflit is: clearrthatz therst'yhzls smay; bee

. bratablexmember:saiditspringrhaving atiits lower ous portions of 'the truss like structure and (16- 1: I

signing: the proper insert, it ispossibleto obtainz the action shown in Figure- 4. This 36131011 15; important-since; it protects the: stylus tip .from breakage vand also protects the delicate rec0rd grooves from-being damaged in case thei'repro- 1 4168 made-travels; across soundtracks;

endaaigenerally v shapled heel pcrtiorr normally: extending. downwardly toward; said: record but= clearing-r'the :same in; normal?- playi'rrg pc'siti'orfi a stylus tip carried by the free end of said v-andf having normal:engagementrwitlra soundQ-trackin same-record; said 'v having the arm's thereof rela tivelyf' rig-ids said spring: generall'y 'd-eterminin'g a plane: intersectingthe=--re'cord along ar lineg'ener allwperpendicularrtcr thersounditrack sat 'thes'tylus; tip; saidiaspringz Being: flexibl'ez along lines per pendioiflanitoathe general spring plane and 'b'ei'ng rigid along flineszlyingrwithin the spring plane," saidf'spring being'iadaptedi to. yieldrupon' excessive: vertical:loadingeitosmovesaidfheel into record en gagem-ent: andr clear it'l'IEiStYlllSiifIOHlZ-Sflifh record. 12h 'llhestructure-ofrclaim .Lwhereimsaids'prdng: has am interior: open:'regiorr"extending-longitudi nellyrther'eof:andiwherein awibration dissipation materiatiisr'disposezriwithimsaid'ire'giorr ancr 'ex' 3. Asstylus" construction for use Witha phonograph reproducercomprising a rigid shank adapted to be gripped in a reproducer and during normal operation pointing generally downwardly from'said reproducer toward a record, a generally fiat spring rigidly carried by said shank and extending toward said record, a stylus tipcarried by the lower end of said spring for engagement with a sound track in said record, said spring generally determining a plane free of the shank center lineand intersecting the record along aline generally perpendi'cular'to the sound track at the stylus tip, said spring being flexible along lines perpendicular to the general spring plane and being rigid along lines lying with the spring plane, said stylus 1 tip being disposed substantially at the intersection of the shank longitudinal center line and the general plane of said spring.

4. The structure of claim 3 wherein a generally V-shaped heel portion is disposed between the lower end of said spring and said stylus tip, said V having the arms thereof relatively rigid, said heel portion extending downwardly toward the record and adapted to engage the same only upon excessive vertical-loading on the stylus tending to flex said spring excessively whereby upon engagement of said heel with said record said stylus tip is cleared from said record.

5. A phonograph stylus construction including a stylus tip for engaging a record groove during normal reproduction, said stylus construction comprising a rigid shank to be gripped in a reprducer and during normal operation positionedso that its longitudinal axis is inclined in the direction of record travel at an acute angle to the record plane, an elongated generally flat leaf spring having one end thereof rigidly carried by said shank and normally extending downwardly toward a record and inclined in the direction of record travel, said leaf spring generally determining a plane intersecting the record plane in a line generallyparallel to a line perpendicular to the direction of record travel at the stylus tip, a stylus tip carried by the free end portion of said leaf spring and normally engaging a record groove, said free end portion having a heel portion extending downwardly toward the record rearwardly of the stylus tip, said heel portion and stylus tip being relatively rigid, said heel portion including a record engaging portion normally clear of the record, said leaf spring being so inclined with respect to, the shank axis that the stylus tip is substantially inline with said "shank axis, said leaf spring being adapted to yield upon excessive vertical loading upon. the stylus to move said heel record engaging portion toengage said-record surface and raise the stylus tip out of normal engagement. r

6. A phonograph stylus construction including a stylus tip for engaging a record groovesduring normal reproduction, said stylus construction comprising a rigid shank to be gripped ina reproducer and during normal: operation positioned so that its longitudinal axis is inclined in the di-- rectionof record travel at an acute angle "to the record plane, an elongated generally flat leaf spring having one end thereof rigidly carried by said shank and normally extending downwardlytoward a record and inclined in the'direction of,

recordtravel, said leaf spring generally. determining a plane intersecting the record in a line generally perpendicular to the direction of record travel at the stylus tip, a stylus tip carried bythe free end portion of said leaf spring and normally engaging a record: groove, said free. end portion- 8 having a heel portion extending downwardly toward the record rearwardly of the stylus tip, said heel portion and stylus tip being relatively rigid, said heel portion including a curved record engaging portion normally clear of the record,

said leaf spring being so inclined with'respect to the record plane that excessive vertical loading upon the stylus will cause downward fiexure of the leaf spring and a downward movement of said heel record engaging portion to engage said recordsurface and raise the stylus tip out of normal engagement.

7, A phonograph stylus construction including portion thereof cut out, vibration absorbing material disposed in said -cutout portion, said leaf spring generally determining a plane intersecting the record in a line generally perpendicular to the direction of record travel at the stylus tip, a stylus tip carried by the free end portion of said leaf spring and normally engaging a record groove, said stylus tip and leaf spring being so inclined with respect to the record plane that said stylus tip is substantially coincident with the longitudinal axis of said shank, said stylus tip being normally in the plane determined by said leaf spring, the free edge portion of said leaf spring being shaped to form a general V with the tip of the V pointing generally downwardly toward the record and normally being clear of the record, said leaf spring being adapted to flex under excessive vertical loading so that the tip of the V will engage the record surface and rock the stylus tip clear of the record.

8. A stylus construction for use with a reproducer, said construction comprising a spring member having one end adapted to be coupled to a transducer, 2. heel structure disposed at the other end of said spring, a stylus tip disposed adjacent said heel, said stylustip being relatively rigid with respect to said heel, said heel normally clearing the record surface but being forced down against the record upon excessive vertical loading of said stylus tip, said heel upon engagement with said record surface functioning as a pivot so that additional flexure .of said spring due to excessive loading causes said stylus tip to be swung upwardly from a record.

9. A stylus construction for use with a reproducer, said construction including a spring trusslike structure normally extending from a r-epro-.

ducer downwardly toward a record, said structure having its upper end coupled to a vibratable mem-.

ber in said reproducer, a heel portion at thelower end of the spring structure and extending downwardly toward the record, a stylus tip rigidly joined to said heel portion, said heel portion being between said spring structure and stylus tip, said truss-like structure generally'determining a plane intersecting the record along a line generally perpendicular to the sound track atthe stylus tip, said structure bein flexible along lines perpendicular to the general plane of the structure and being rigid along lines lying within the general plane of the structure, said heel portion being 9 normally out of contact with said record but upon excessive vertical loading and consequent yielding of said structure said heel approaches said record and contacts the same to function as a pivot for I rocking the stylus tip up from the record.

10. A stylus construction for use with a phonograph record reproducer, said construction comprising a spring member having one end adapted to be coupled to a transducer, a heel structure disposed at the other end of said spring member, a stylus tip disposed adjacent said heel, said stylus tip being relatively rigid with respect to said heel, said heel normally clearing the record surface but being forced down against the record upon excessive vertical loading of said stylus tip, said heel upon engagement with said record surface functioning as a pivot so that additional flexure of said spring due to excessive loading causes saidstylus tip to be swung upwardly from a record, and vibration damping material disposed along said spring member.

11. A stylus construction for use with a phonograph record reproducer, said construction comprising a rigid shank adapted to be gripped in a reproducer and during normal operation pointing generally downwardly from said reproducer toward a record, the downward end of said shank including a lateral extension, a spring member rigidly carried at one end by said extension and extending toward said record, a heel structure disposed at the record end of said spring member, a stylus tip disposed adjacent said heel, said stylus being relatively rigid with respect to said heel, said heel normally clearing the record surface but being forced down against the record upon excessive vertical loading of said stylus tip, said heel upon I engagement with said record surface functioning as a pivot so that additional fiexure of said spring member due to excessive loading causes said stylus tip to be swung upwardly from a record.

BENJAMIN B. BAUER.

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

UNITED STATES PATENTS