US2293220A - Stylus head mounting - Google Patents

Description

Aug. 18, 1942.

F. RIEBER STYLUS HEAD MOUNTING Fil ed Aug. 2, 1941 INVENTOR B Fm kick/- Y 6 ATTORNEY" Patented Apr. 18, 1942 UNITED STATES -PATENT OFFICE smus HEAD Momma Frank 'Bieber, Lbs Angele s, ,CaliL, allignor to Memovox, tlon of Ohio lnc., Beverly Hills, Call! a corpora- J Application August 2, 1941, Serial no. 405,178 .11 chums. (01.2751)? In commerciah recording machines, such as used formaking records of dictation, aircraft communications, and the like, it is frequently necessary to playback or reproduce some or all of the material just recorded. For this purpose, such machines are often equipped with a single apparent that even a very 'slightmovement will be suilicient to injure, the groove, and the movehead carrying a record engaging stylus, which by appropriate switching of the amplifier connectionscan be caused'optionally to act .as a recorder in response to modulations received from a microphone or to operate as a reproducer, to

affect a'speaker in response to undulations of a record.

Whenmaking, a record, the stylus forms the record groove and hence must be positively advanced across the record surface in exact accord ance with the movement of the feed mechanism.

a In reproducing a record, however, while it is still desirable to positively advance the stylus over the record, a limited freedom of movement between the feed mechanism and the stylus is re- 'quired, in order that thestylus be permitted 'accurately to follow the record grooves; Such freedom of movement 'is' conveniently termed flateral compliance. l

Further, it is obviously necessary that the stylus exert a considerable pressure on the recment may easily be sumcient to cause the stylus to cross from one groove to the adjoining groove and permanently injure the record.

It is accordingly another object of the invention to provide mechanism of the character describedwhich will lock the head against lateral compliance'without causing any lateral movef ment of the head.

It is still another object of this invention to provide mechanism'of the character described of increased simplicity and 'ease of operation. This invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of one embodiment of the invention. For this purpose there is shown a form in the drawing accompanying and mm; part of the present specisense, since the-scope ofthis invention 0rd when cutting or' embossing a record; but

. when playing .back a previouslymade record, the

pressure should be quite light.

It is an'object of this invention to provide an improved mechanism for changing the condition of a stylus head to prevent or to allow such free-' dom or lateral compliance.

, It, is another object of this inventionto-provide improved mechanism for. altering the pres sure exerted by the stylus on the record.

I Devices for locking such heads against lateral compliance usually involve some sort ofa con- 'straint against motion of'the headabout an axis;

as for example a'centering arrangement, such as a pin seating in a V-notch. 'Ihestylus is correspondingly forced into a defln'iteposition with respect to the feed mechanism, and is maintained in that position while .the constraint is effective. Nevertheless, after the record groove is provided with the undulations forming the record, the position of the stylus under the constraint isapt to 'be slightly incorrect forthereproducing position. This may be due to a slight eccentricity of the groove, or other causes. Therefore the operation of locking will almost certainly cause a 'slight claims.

jll'igs. 2, 3 and 4 are sectional viewsas taken on 1 the correspondingly numbered planes of 'Fig, l.

' A phonograph turntable is indicated by I, and

-may be of anywellknown or preferred type,

serving to carry a record 2. Although a disc 'form of record is shown, the mechanism about to be described is equally applicable to acylindrical record, or a recordin the form of a loop.

The stylus 3 which cooperates with. the record surface is shown, for example, as carried by an electrical type stylus head 4. This head is of a type which will function either as a recorder or a reproducer, suitable circuits being provided by means of which it maybe optionally connected .to a r a microphone or a speaker through a suitable Such '.heads and circuits are well amplifier. known to those skilled in the art, and accordingly will not be' further described.

. The head 4 is mounted on a short arm 5 which" is attached to a carriage i by a pivoted connection I. Carriage 6 maybe supported formovement parallel with the surface of record 2 by spaced parallel rods 8. suitably supported as on lateral movement of the stylus on the record.

' Since record grooves are commonly spaced in the neighborhood of 150per-inc'h, it will be readily the frame of the phonograph (not shown). The carriage 6 is caused to travel along rods 8 and thus traverse the record by means of a feed screw turntable I.

9, engaged by a frictional nut l mounted on carriage 6 by a resilient arm II.

The feed screw 9 is rotated at a definite angu-- shown). .Thus the stylus follows a spiral track extending between the periphery of the record and a point near the center of the record.

The pivoted connection I (shown most clearly in Fig. 3) includes a clevis l3 with a shank l4 supported in a suitable bore in a boss IS on the carriage 6 We washer l6 and a pin I! on top of lar velocity with regard to the angular motion of the turntable by appropriate mechanism (notthe boss. Accordingly clevis I3 is rotatable about an axis l8 normal to the surface of the record 2. In the legs I! of clevis l3 are alined pivot points 20 engaging opposite sides of arms 5. The axis 2| of pivots is substantially parallel to the record surface. Pivots 20 may conveniently be hardened cone pointed screws. 1

When head 4 isfunctioning as a reproducer, the stylus 3 must follow the spiral groove 'on the record surface. Since the position of this groove may not at all times coincide with the position .of the stylus as determined by movement of car'- riage- 6 in response to feed screw 9, the head 4 must have some freedom-of motion laterally of the record with respect to the carriage. so called lateral compliance is provided by slight angular movement of head 4, arm 5 and clevis.

l3 about axis l8. Similarly stylus 3 must be free to follow. undulations of the record surface in a generally vertical direction; such movement is permitted head 4 and arm 5 with respect to clevis l3 and carriage 6 about axis 2|. Stylus 3 is thus enabled to follow all deviations of the record groove without undue wear or damage to the groove. At the same time, the advance of carriage 6 carrying thehead 4 relieves this groove of the necessity of moving any substantial mass.

is secured on ar extending away from the head and beyond the axis 2|. This finger 23 is without effect when the head is reproducing other than to restrict the-lateral, freedom of movement to a reasonable amount.' Thus, pins 24 and 25 extend downwardly from carriage 6, a short distance on opposite sides respectively of finger 23. These pins by engaging one side or the other of finger 23 serve to limit the. movement of the finger, arm 5 and head 4, when for example the head 4 is lifted manually about axis 2| to remove and replace a record on the ,A plunger 26 is slidably mounted for vertical movement on carriage 6 in boss 2'! and carries an abutment 28 at its lower end, adapted to engage the free end 29 of finger 23 when the plunger 26 is raised. When the plunger 26 is in its lower position abutment 28 is entirely clear of finger 23. When the plunger 26 is raised, abutment 28 engages end 29 of finger 23, and flexes the finger 23 until end 29 engages a friction pad 36 of fibre or felt or the like on carriage '6 as shown in broken lines, Fig. 1.

Means are provided for causing plunger 26'to urge the extremity 29 of finger 23 against pad 30 with sufiicient force to' maintain arm 5- and connected parts against movement about -axis IS in response to forces incident to recording.

Thus head 4 ismoved accurately by carriage 6, stylus 3 forming the record groove. At the same time, the upward flexing of finger 23 exerts a downward force on head 4, and augments the pressure exerted by stylus 3 on the record.

and finger 23 which contact are plane, thus the force urging them together has, no tendency whatever to move the finger, arm- 5 and head 4 laterally of the record, about-axis l8,

One mechanism for moving plunger 26 and spring finger 23 upwardly and maintaining the latter in engagement with pad 30 may comprise electromagnetic means.. Thus, plunger 26 carries f a core 3|, of magnetic material, on its upper end. Core 3| cooperates with a solenoid, diagrammatically shown at 32, adapted to be ener-- gized from any convenient source, such as battery 3'3, controlled by a manually operable switch 34.

When it is desired to use stylus head 4 for reproducing, switch34 is allowed to remain open,

deenergizing .coil 32. Plunger 26 will then' remain in its lower position, without affecting spring finger 23. When it is desired to record,

switch 34 is closed, energizing coil 32 which causes plunger 26 torise to its upper position,

- flexing spring finger 23- and urging it against pad 30. This-locks the head 4 against lateral to the-head 4 when-the plunger 26 is allowed to I ing conditions of thehead 4, a spring finger 23 compliance and increases the pressure of stylus 3 on the record. It is to beunderstood that on occasions when it is necessary to lift the .stylus out of" engagement with the record, upon re- 3 placing it on the record, the head should be positioned so that finger 23 is approximately intermediate the pins 24, and 25.

In order to prevent. any slight blow or shock drop to .its lower position, a resilient ring. or

- bumper 35 formed of rubber for example may be provided on boss 21 to act as a stop for'core 3|.

What is claimed is:

I 1. A stylus head, arranged to cooperate with a record, a carriage arranged to move the head transversely of the record, means forming a pivotal support for the'head on the carriage,-'said support permitting movement of .the head to or from the record surface, a spring finger attached to the head and having a'free end, a plunger carried by the ca-rriageand optionally movable with respect thereto, said plunger being adapted upon movement to engage the free end of the spring finger, flexing the spring and urging the head about said pivotal support.

2. A stylus head, arranged to cooperate with a record, a carriage arranged to move the. head.

transversely of the record, means, forming a pivotal support for the head on the carriage, said support having a pair of pivotal connections, said connections having axes respectively parallel with and transverse to, the record surface, means for urging said support toward the recordsurface comprising a spring finger on said head; means on the carriage for optionally flexing the finger, and means on the carriage adapted to be v 3. In a stylus head mounting, a carriage arranged to move transversely of therecord surface, means connecting the head for movement It willbe noted that the surfaces ofpad 30 1 with the carriage comprising means whereby the head may have limited lateral movement with respect to the carriage, as well as movement to and from the record surface, means to secure the head against lateral movement'with respect to the carriage comprising a resilient member attached to the head, a friction padon the carriage, and means to flex said member and urge it into engagement with said pad, said member being so arranged that the flexing urges the head toward-the record surface.

4. In a stylus head mounting, a carriage arranged to move transversely of the record surface, means for supporting the head on the carriage including a pivotal connection about which the head may move transversely of the record,

and means to restrain said head against movement about said pivot, comprising a resilient member attached to thehead, a friction pad on the carriage, and means for urging said member into engagement with the pad.

5. In a stylus head mounting, acarriage arranged to move transversely of the record surface, means for'supporting the head on the carriage including a pivotal connection about which the head may move transversely of the record, and means to secure said head against movement about said pivot, said means serving to'se'cure transversely of 'the record surface, and a support on the carriage for the head, permitting universal movement ofthe head with respect to the carriage, said support comprising a pair of pivotal connections, the axes of said connections being normal with respect to each other.

9. In a stylus head structure adapted to operate optionally as a recorder head or as a reproducer head, a movable carriage upon which the head is supported, means for providing lateral compliance for the head with respect to the carriage, and means for optionally restraining the head against lateral movement, comprising a pair of members respectively carried by the head and by the carriage and having cooperating frictional surfaces, said surfaces being capable of opera tive engagement for any position of the head said head in a lateral position as determined solely by the engagement of the stylus with the record. s

6. Astylus head for cooperation with a record, a carriage arranged for movement transversely of the record, said head being pivotally carried by the carriage whereby the head may move independently of the carriage, a spring finger at tached to the head and arranged to affect the movement of the head. with respect to the carriage when flexed, and means for flexing said 1 finger, said means including a plungeron the carrlage 'and electromagnetic means for moving said plunger. e

'1. Ina stylus head mounting, an arm to which the head is attached, a pivotal support for the,

arm, said support being so arranged that the head can move toward or away from the record surface, a leaf spring secured at one end on said arm and extending in a generally radial direcv surfaces, one of said members being resilient and capable of exerting a pressure on the head when the surfaces are in frictional engagement, and

' means to bring said surfaces into engagement.

11. In a stylus head structure adapted to operate optionally as a recorder head or as a reproducer head, a movable carriage'upon which the head is supported, means for-providing latv eral compliance for the head with respect to the carriage, and means for optionally restraining the head against lateral movement, comprising a pair of members respectively carried by the head and by the carriage and having cooperating frictional surfaces, one of said membersbeing resilient and capable of exerting a pressure on the head when the surfaces are in frictional ention from the arm with respect to said pivot, and

means for flexing said spring to cause it to exert a force urging said arm about its pivot.

8. In a mounting for a stylus head, said stylus head being arranged for cooperation with a rec- 0rd surface, a carriage arranged for movement gagement, said surfaces being such as to permit operative engagement for any position of the head with respect to the carriage, within the limits of movement permitted by said lateral compliance, and means to bring said surfaces into engagement.

FRANK RIEBER.

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