US2542534A - Tone arm - Google Patents

Tone arm Download PDF

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Publication number
US2542534A
US2542534A US574052A US57405245A US2542534A US 2542534 A US2542534 A US 2542534A US 574052 A US574052 A US 574052A US 57405245 A US57405245 A US 57405245A US 2542534 A US2542534 A US 2542534A
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Prior art keywords
arm
cartridge
needle
rotor
tone
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Expired - Lifetime
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US574052A
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Robert S John
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PFANSTIEHL CHEMICAL CO
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PFANSTIEHL CHEMICAL CO
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    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B3/00Recording by mechanical cutting, deforming or pressing, e.g. of grooves or pits; Reproducing by mechanical sensing; Record carriers therefor
    • G11B3/02Arrangements of heads

Description

R. S. JOHN Feb. 20, 1951 TONE ARM 2 Sheets-Sheet 1 Filed Jan. 23, 1945 fiver? an [3 0567713 R. s. JOHN 2,542,534
TONE ARM 2 Sheets-Sheet 2 Feb. 20, 1951 Filed Jan. 23,
42587713 Jazz,
Patented Feb. 20, 1951 UNITED STATES PATENT oFFice TONE ARM4 1 Claim; (01. 2i 4"-23') This invention relates to atone arm and parpressureraridto provide a heavy-baseelemeiit on" ticularlyjto astone arm assembly ina recorde which the supported "end of the arm"is pivoted;']- playing device in which theprincipal function of to-producea high momentofinertia; witha light thetone arm istoprovide a movable holder to weight-arm; .tha-t' can-rotatehorizontallywith carry the translating means andneedle across=5 thearrn-and provide'amextra'amountof horizon the record.
talstabilityfor the cartridgef I a I Among the objects-of the'inventionis to-pro- Further-objects, advantagesand capabilities? vide a movable-extension arm which will efiect inherently :possesse'd' by my invention will later stable support-for'an .apparatuscapable of--trans+ more fully becomeapparent. I I latinga forced vibration into a fluctuating elec l My' invention further resides-in thecombinaif trio current; further to provide -atone 'ar'm in tion, construction and arrangementfof'parts" ilwhich 7 the cartridge housing-a the translatinglustrated--in 'the accompanying drawin s; and" means-dis set'at'anangle to-the arm to allow the .whileI have 'shown 'therein' preferred eI'r'ibodi-" needle to cross the record approXimate1yon a ments I wish-it understoodthat-"the:same"are radius and the cartridge be as nearly tangent to 16 susceptible "of modifica'tion and change-without each" record'groove as possible; still fur-ther to departing from the spirit of my invention. provide a tone arm that 'wi'll'function with a low- In thedrawings: I I needle pressure and supply sufiicient momentum Figfil is a side "edge elevation of'fa tone armyand inertia to-allow the needle'to reproduce a embodying my inventionand showing -a record broad range offrequencies :with' high-fidelityy-i-ZO tableand record'in-dotted'lines-E II I I yet further; the-feature of providing-a novel' tone- Fig-f2 is :a top' plm' VieWbf-the'tme arm as arm in which the center: of gravitysof the car sembly-bf II II I I I tridge and-arm is near'the needle-point; thefur=-- Fig'. 3 is a vertical' transverseI se'otion onithe ther feature of providing ato'ne' arm-in 'which' line 3'"3"of-Fig. 2 looking in the direction of the the arm and cartridge. are'free torotate in ver' arrowsi I I ticalplanesl and horizontalflplanea but no fur Fig; 4 isavieW-similar to that of-Figf l but thermotion; alsostoprovide a tone arm-'compris"- Showing-a modified form of 'my inventi V ing a framework or arms madebf thin wall tub g 'iS'a toprlan 'V W he o'n afhi as ing and so constructed and arranged 'as:to 'pre sembly shownin Fig.4;" I I I vent any wobbling of'the cartridge; further 'the Figx 6 is a vertical transverse'section "on thefl provision of a movable vibration damper that can lin'e- 6+6 of Fi"g;- 5 "looking inthe direction of beselectively fastened tonne of the -arm -mem"- the'arrowsi" I t any point Where-a vibration. p Referring mo re-in detail to the drawings my: occur-at-low frequencies, andto-preventorm preferred "form" of the invention is shown inf Figs. --'-1-3'-'and comprises a pair of spacd apart angularly arranged arm-elements I and- 2 as; shown 'in Fig. 2 and rigidly 'con-r'iecte'd together at "their forwardends by a eonnectingarins and at their rear ends by a curved U-shaped mem ber"4. Therear ends of the arm elements are I rigidly-securd to' the U-shapedmi riber 4 byff any-suitable means tofrigidly' 'hold thes'e parts also to place'the connecting wires ins'ide'of the tubing to shield themrfrom any outside-magnetic or electrostatic fields; to provide small s ur-i ace tridge; also to provide'weightsfor thecartridge so as to locate the center'of gravity'of the arm-- and cartridge near'the needle, and yet have low" needle pressure, and a light-weight arm com-'-' pared to the weight of the cartridge, so that the moment .of inertia ofthe arm and=cartridge-,:" later more fully described. I about'itsnhorizontal pivotalsupport,will be ash The armelements land 2' are e'x'tl'al'idecl"forgreat as possible for its total weight and needle wardly beyond the cross member 3 and bent ana vertical' swinging movementabout pins-6 gularly a small amount as indicated at 8 and 9, these extending ends being inserted into holes in the rear end of the cartridge and secured therein by set screws or the Lke l l or any other suitable fastening means to hold the cartridge securely and firmly to the arm elements I and 2.
The translating or needle element 12 preferably consists of a small plastic moulding having a larger flag portion l3 which is held in the cartridge by any suitable number or screws M, or other suitable fastening means, as seen in Figs. 1 and 2. The smaller extension portion or vibratory arm of this translating element holds the needle pointor stylus i5. The vibratory arm is of insulating material, as polystyrene, and at least one surface has a strain-sensitive coating, as of colloidal graphite, whereby fiexure of the arm varies the resistance of the coating and provides the desired electrical variations. Translating elements of this type are shown, for eX- ample, in Germeshausen Patent 2,329,526. The end of this vibratory arm must be free to follow the record groove, and the vibration of the needle point, and the bend-ng of the needle arm, should not be transmitted to the cartridge or any other part of the whole tone arm. To accomplish this the cartridge It, the tone arm T and the rotor 1 must provide a sufficient amount of inertia and stay within the desired low limits of needle pressure. It is desirable that the center of gravity of the cartridge and arm T should be as near the needle point and as low as possible in position and weight. To facilitate this, weight-elements l6 are provided in the cartridge near its forward end. In the particular arm and cartridge assembly here being described, the center of gravity of the combination is slightly forward of the rear end of the cartridge; and it is preferably not more than one-third of the distance from the needle to the mounting point in any construction.
The arm T and cartridge must be free to rotate in vertical planes about an axis passing through the axis of the fulcrum pins 6- and through the center of rotation of the rotor 1, which rotor rotates in a horizontal plane about its vertical axis. This vertical and horizontal movement of the arm T must be accomplished freely without any other motion. The rotor I is relatively heavy and has comparatively large mass distributed more or less similarly to a fly wheel, in order to provide the greatest amount of inertia for the weight actually used. For convenience the fulcrum points between the rear ends of the armelements I and 2 and the rotor l are indicated at A and B which points are preferably from two to three inches apart. This assembly of rotor 1, arm '1 and cartridge It provides an amount of inertia in the plane indicated by the points AB! 5, which holds the flag l3 of the needle in sufiiclent equilibrium while the needle vibrates. The construction of the rotor and the supporting parts later described should be such that the plane ABI5 is either parallel to or at a small angle to the surface of the record [1 for this inertia to be most eifective.
The support for the tone arm comprises the rotor i above referred to, the ball-type thrust bearing it, the stator l9 and the damper having a central opening 2|. The stator has a central opening 22 screw threaded to receive complemental threads on the lower end of the tubular pivot pin 23 which is rigidly mounted in the stator to project upwardly therefrom through complemental central openings in the thrust bearing and the rotor, the rotor being rotatably 4 mounted upon tube 23 but without any looseness that might allow vibration in the rotor. The thrust bearing I8 is provided with an annularly arranged series of openings 24 receiving the antifriction balls 25. The damper element 20 i of any suitable material to absorb any vibration that might be set up in the tone arm as a whole and to prevent any vibration being transferred from the support to the tone arm.
Longitudinally movable along either one or both of the arm-elements l and. 2 is a vibration damper 26 which is a mass of any suitable material that can be selectively fastened to the arm-element at any point where a vibration position might occur at low frequencies, and the function of which is to interfere with any natural resonant frequency that might occur in the arm-elements and to reduce or prevent such vibrations from occurring. The arm-element l and 2 are purposely made of thin-walled, small diameter, metal tubing which is grounded. The wires to the needle are placed inside of these tubes which shield them from any outside magnetic or electrostatic fields. The small surface area reduces practically to Zero any sounding board effect that might be caused by any forced vibration that might get into arm T from the cartridge. The surface of the arm T, the cartridge Ii! and the rotor 1 may be covered with some soft material, as a sprayed plastic coating, that will interfere with the transmission of any vibration to the air.
As will be understood the rotatable record head I! will be driven by any suitable means within a cabinet or other suitable housing, the surface of which is indicated at 21, the support 1, l8, l9 and 20 also resting upon surface 2'! at a point adjacent the edge of the rotating record holding table H, the record being indicated in dotted lines at 28.
The form of my invention shown in Figs. 4-6 is in general the same as that shown in Figs. 1-3 except for detailed structural differences. The support for the tone arm consists of the rotor 31, stator 38, and soft vibration damping base 39, the rotor 31 being rotatably mounted on the stator 38 by means of a pin 40 threaded into the stator and having at its upper end a head 4| between which head and the bottom surface 42 of the depression 43 is mounted a spring 44 to yieldably hold the rotor against the stator, the rotor being rotatable about pin 40 with a close rotatable fit in order to prevent any vibration between these parts. Formed on the lower face of the rotor is an annular flange 45 provided with a flat bottom face to have rotatably sliding movement upon the upper face 46 of the stator so as to decrease the friction between these parts and enable an easy but vibrationless rotation therebetween. This flange 45 should be of substantial diameter for stability, but not so large as the rotor 37, to minimize frictional resistance.
The tonearm indicated generally at T in Fig.
- 5, comprises the arm-elements 41 and 48 which may be of any desired small cross section, these arms being preferably made of very thin metal tubing through which the wires from the needle extend. The rear end of the tone arm is pivotally mounted to the rotor by the fulcrum pins 49, the axis of which when extended intersects the axis of rotation of the rotor. The holes in the rear ends of arm elements 41, 48, through which the fulcrum pins extend, are of a close rotating fit so as to prevent rotation between these parts, the fulcrum pins 49 being threaded into the rotor and screwed inwardly so asto permit free rotation but prevent any looseness" or vibration. The cartridge is rigidly attached to the front'ends of thearm-elements 41, 48, in the position shown'in Fig. 5, this form of cartridge also having weight elements 50 in the forward end similar to the elements It in Fig. 2. The arm-elements ll, 48 areconnected together at their respective ends by crossbraces 5| and 52 which areheld rigidly but longitudinally adjustably to these arm-elements by tighteningthe screws 53 and 5 3. Vibrational damping material will be positioned around the transversecross brace 52 to function in a manner similar to that described abovein connectionwith the vibration damper 26. Cross braces 5i and 52 also contain wood cross supports a and f {preferably softwood with the grain longitudinally of the armfwhich serves well as vibration dampeners and can be shifted to find an anti-nodal point. Cross braces 51 and 52, as will be understood. also give 'added rigidity to the tone arm T as a whole. Damping material will also be positioned around the fulcrum pins 29 to further prevent vibration.
The forms of my invention described above give very desirable resilience and flexibility to the tone arm. It is important to note that the small surface area of the arm-elements of my novel tone arm reduces the effect of forced vibration, and that the damping reduces vibration from the cartridge to the arm and allows a slight flexibility which means better tracking. Also the center of gravity of the arm and cartridge combination is kept as near the needle point as possible, and my construction as described is such that it tends to have as high a moment of inertia about the pivot as is possible with its weight which is kept low by light weight construction and which in effect causes the motion of the arm and cartridge combination to simulate that of a simple pendulum.
The tone arm and cartridge of the present invention is such that the needle will track better and follow record warping or other irregularities better and with less needle pressure than any tone arms heretofore known. In the present construction I have made possible a very light needle pressure, for example between A and one ounce, and preferably in the neighborhood of from to ounce, in connection with which it is important to note, as stated above, that the center of gravity is near the needle and that counterbalancing has been entirely eliminated. This device will operate eiiiciently at very low needle pressures. I have provided a very solid cartridge that can clamp the needle rigidly for the best results and vibration of the needle is permitted without creating undesirable vibrations in the other parts, it being noted in Figs. 1 and 2 that suflicient space is provided for around the needle portion I2, while at the same time firmly clamping the flag l3 in the cartridge and firmly connecting the cartridge to the front end of the arm-elements.
The cartridge is formed with thin construction in order to reduce its weight and still maintain its strength, it being noted that the height of the cartridge has been kept low. The balance point of the arm is quite close to the rear end of the cartridge, and this sets up a high moment of inertia considering its total weight, to resist any rotational disturbances in a horizontal plane which is the direction from which outside disturbances would come.
respond simultaneously with the disturbances This inertia effect must ndw li Q ,SQ if hem. ment.o.inertia, .is ,ashigh.
si siblei 'if e irediitheicartridgefmaygibesiip; j
ported fror'n the tubing of the tonjeiarjnif by means.
of ei e j m in'e material to forth Eliminate;
I a flexibility that very materially. increases ,the. life 7, of the 1 records;
" The cartridge] should .be;
comparatively fiatQandQnot. t .p. .haviy truer.
tohelp minimize'a twistingtype'of vibration that might occurespecially in the cartridge ma ver-" ticalplane"at"rightangles to the line passing through the point of theneedleand the center of rotation of the rotor T. Th e extra width betweenthe'pointsAHatthe rear I arm helps reduce the objectionable vibration just referred to The tone arm.tubingserves as a shield for. the Wires which will run through. it
as stated above and the usei'ofjfsrnall.tubinghelps cause thebulk of the weight toibefi'nithe cart gje. Needle pressures between and one mascara preferable, the lower values being used when suiiicient tracking on the record is obtained.
In order to have the greatest possible vibration response in the needle and the least amount in the cartridge and tone arm, the metal needle tip in its plastic mould is made as light as possible and the tone arm relatively heavy. In tone arms prior to the present invention this latter weight is supplied by a heavy tone arm having a considerable amount of distributed weight, and in some tone arms the arm extends back beyond the pivotal point so as to carry a counterweight which is ample to control the needle pressure, while in some instances the arm extends back beyond the pivoted point so that a variable spring can be attached to control the needle pressure. The effect of such prior tone arm is to make the natural motions of the entire arm about a vertical axis in the base and support similar to that of the compound pendulum and thus slow and sluggish. Such compound pendulum effect also slows any tone arm motions around the horizontal axis in the support. These tone arm motions need to take place to allow the needle to track on warped or eccentric records and to move it as it follows the groove. The tone arm of my present invention has no compound pendulum effect but moves quickly and eificiently similar to the motons of a short simple pendulum and this allows it to trace any record irregularity in a much surer and positive manner.
In order to have the greatest possible vibration in the needle and the least in the cartridge and tone arm the moment of inertia of the assembly should be as great as possible consistent with its total weight, needle pressure and necessary design limitation. This relatively large moment of inertia is obtained by keeping the weight of the tone arm low and the weight of the cartridge as high as a limited needle pressure will permit. Also the center of percussion should be in the front end of the moulding that holds the metal needle. The cartridge should be kept reasonably small and as compact as possible.
Having thus described my invention, I claim:
A tone arm comprising a light-weight rigid arm having small surface area, said rigid arm comprising two spaced tubes of small diameter rigidly held for movement as a unit, a cartridge rigidly carried near one end of said arm, said end' of the .tone
of to locate the center of gravity of the arm and cartridge nearer the cartridge than the other end of the arm, a support of relatively large mass compared to the mass of the rigid arm comprising a rotor and a stator, the rotor being rotatable on the stator in a horizontal plane, and means for mounting the other end of said tubes on opposite sides of said rotor for rotation therewith in the same direction and for pivotal movement in vertical planes, the points of pivotal mounting on opposite sides of said rotor being spaced substantially farther apart than the width of said cartridge.
ROBERT S. JOHN.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Number Name Date Theis Mar. 1, 1921 Cheney Nov. 27, 1923 McClatchie Nov. 10, 1931 Forte Apr. 2, 1935 Proctor Nov. 10, 1936 Thompson Oct. 18, 1938 Hutter Apr. 1, 1941 Vermeulen Jan. 19, 1943 Dally Mar. 9, 1943 Andres Aug. 10, 1943 Germeshausen Sept. 14, 1943 Jones Oct. 5, 1943 FOREIGN PATENTS Country Date Great Britain Oct. 27, 1927 Great Britain Dec. 12, 1929 Great Britain Apr. 17, 1930 France July 31, 1933 Great Britain Oct. 22, 1934
US574052A 1945-01-23 1945-01-23 Tone arm Expired - Lifetime US2542534A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2658115A (en) * 1949-07-09 1953-11-03 Hartford Nat Bank & Trust Co Phonograph pickup
US2784586A (en) * 1953-09-25 1957-03-12 Sr Milton C Campbell Watch timer
DE1043650B (en) * 1956-05-28 1958-11-13 Electroacustic Gmbh Record player with a device for changing the weight of the tonearm
US3531130A (en) * 1968-12-06 1970-09-29 Gen Electric Pivotal support assembly for phonograph record and playback arms
US4147364A (en) * 1977-03-30 1979-04-03 Namiki Precision Jewel Co., Ltd. Non-vibration tone arm
FR2525060A1 (en) * 1982-04-08 1983-10-14 Rca Corp DEVICE FOR MAINTAINING A NEEDLE FOR READING VIDEO DISC SIGNALS
US4434483A (en) 1981-11-27 1984-02-28 Vinogradov Vladimir F Tone arm

Citations (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US892520A (en) * 1908-03-07 1908-07-07 Joseph Oakland Hirschfelder Apparatus for phonographs and graphophones.
US1325209A (en) * 1919-12-16 Phonograph
US1370382A (en) * 1921-03-01 thjis
US1475277A (en) * 1918-02-15 1923-11-27 Cheney Talking Machine Company Tone-arm support
GB307091A (en) * 1927-10-27 1929-02-27 William Ernest Clifton Improvements in or relating to means for supporting electrical sound-recording or sound-reproducing or other like electrical vibratory devices
GB322663A (en) * 1928-12-22 1929-12-12 Wireless Music Ltd Means for securing improved needle track alignment in disc talking machines
GB328039A (en) * 1929-01-17 1930-04-17 Jean Dieux Improvements relating to sound-reproducing or recording machines
US1830800A (en) * 1929-12-07 1931-11-10 Mcclatchie Stanley Electromagnetic pick-up
FR752864A (en) * 1932-07-02 1933-10-02 Improvements to so-called pick-up "electromagnetic readers" devices
GB418373A (en) * 1933-04-21 1934-10-22 Emi Ltd Improved mounting for the reproducer of a talking machine
US1996104A (en) * 1932-08-17 1935-04-02 Frederick D Forte Wave damping response device
US2060117A (en) * 1934-04-24 1936-11-10 B A Proctor Company Inc Phonograph
US2133596A (en) * 1936-04-23 1938-10-18 Thompson Lincoln Feed mechanism for disk recording machines
US2236599A (en) * 1938-08-06 1941-04-01 William H Hutter Pickup arm
US2308795A (en) * 1938-08-05 1943-01-19 Rca Corp Supporting arm for sound boxes and sound recorders
US2313126A (en) * 1941-01-18 1943-03-09 Webster Electric Co Inc Tone arm
US2326424A (en) * 1943-04-17 1943-08-10 Permo Products Corp Phonograph stylus
US2329526A (en) * 1941-09-17 1943-09-14 Kenneth J Germeshausen Translator
US2331122A (en) * 1940-12-11 1943-10-05 Jones Allen Monroe Stabilized phonograph arm

Patent Citations (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1325209A (en) * 1919-12-16 Phonograph
US1370382A (en) * 1921-03-01 thjis
US892520A (en) * 1908-03-07 1908-07-07 Joseph Oakland Hirschfelder Apparatus for phonographs and graphophones.
US1475277A (en) * 1918-02-15 1923-11-27 Cheney Talking Machine Company Tone-arm support
GB307091A (en) * 1927-10-27 1929-02-27 William Ernest Clifton Improvements in or relating to means for supporting electrical sound-recording or sound-reproducing or other like electrical vibratory devices
GB322663A (en) * 1928-12-22 1929-12-12 Wireless Music Ltd Means for securing improved needle track alignment in disc talking machines
GB328039A (en) * 1929-01-17 1930-04-17 Jean Dieux Improvements relating to sound-reproducing or recording machines
US1830800A (en) * 1929-12-07 1931-11-10 Mcclatchie Stanley Electromagnetic pick-up
FR752864A (en) * 1932-07-02 1933-10-02 Improvements to so-called pick-up "electromagnetic readers" devices
US1996104A (en) * 1932-08-17 1935-04-02 Frederick D Forte Wave damping response device
GB418373A (en) * 1933-04-21 1934-10-22 Emi Ltd Improved mounting for the reproducer of a talking machine
US2060117A (en) * 1934-04-24 1936-11-10 B A Proctor Company Inc Phonograph
US2133596A (en) * 1936-04-23 1938-10-18 Thompson Lincoln Feed mechanism for disk recording machines
US2308795A (en) * 1938-08-05 1943-01-19 Rca Corp Supporting arm for sound boxes and sound recorders
US2236599A (en) * 1938-08-06 1941-04-01 William H Hutter Pickup arm
US2331122A (en) * 1940-12-11 1943-10-05 Jones Allen Monroe Stabilized phonograph arm
US2313126A (en) * 1941-01-18 1943-03-09 Webster Electric Co Inc Tone arm
US2329526A (en) * 1941-09-17 1943-09-14 Kenneth J Germeshausen Translator
US2326424A (en) * 1943-04-17 1943-08-10 Permo Products Corp Phonograph stylus

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2658115A (en) * 1949-07-09 1953-11-03 Hartford Nat Bank & Trust Co Phonograph pickup
US2784586A (en) * 1953-09-25 1957-03-12 Sr Milton C Campbell Watch timer
DE1043650B (en) * 1956-05-28 1958-11-13 Electroacustic Gmbh Record player with a device for changing the weight of the tonearm
US3531130A (en) * 1968-12-06 1970-09-29 Gen Electric Pivotal support assembly for phonograph record and playback arms
US4147364A (en) * 1977-03-30 1979-04-03 Namiki Precision Jewel Co., Ltd. Non-vibration tone arm
US4434483A (en) 1981-11-27 1984-02-28 Vinogradov Vladimir F Tone arm
FR2525060A1 (en) * 1982-04-08 1983-10-14 Rca Corp DEVICE FOR MAINTAINING A NEEDLE FOR READING VIDEO DISC SIGNALS

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