US2332784A

US2332784A - Combination sound recorder and reproducer

Info

Publication number: US2332784A
Application number: US419361A
Authority: US
Inventors: Sr Albert W De Sart
Original assignee: UNITED ACOUSTIGRAPH CORP
Current assignee: UNITED ACOUSTIGRAPH Corp
Priority date: 1941-11-17
Filing date: 1941-11-17
Publication date: 1943-10-26
Anticipated expiration: 1960-10-26

Description

1943- A. w. DE -SART, SR ,33

COMBINATION SOUND RECORDER AND REPRODUCER Filed Nov. 17: 1941 5 Sheets-Sheet 1 INVENTOR W 0e50r/7 5 BY ATTORNEY Oct. 26, 1943. A. w. 'DE SART, sR

COMBINATION SOUND RECORDER AND REPRODUCEB Filed Nov. 1'7, 1941 3 Sheets-Sheet 2 l! lllllll "INVENTOR a #N ,m R 0 k WA r a Y 5 Oct. 26, 1943. A. w. DE SART, 8R

COMBINATION SOUND RECORDER AND REPRGDUQER 3 Sheets-Sheet 5 Filed Noy. 17, 1941 Imp/19%! 'INVENTOR TORNEY Patented Oct. 26, I

Albert w. De Sart, SnQLos Angeles, Calii'., as-

slgnor to United Acoustigraph Corporation, Los Angeles, Calii., a corporation of. Nevada Application November'l'l, 1941, Serial No. 419,361 19 Claims. (01. lie-100.4)

This invention relates to apparatus for record- 'ing and reproducing sound. More particularly, the apparatus contemplates the use or a'stylus thatforms a record groove, for recording, or that cooperates with a previously formed groove for reproduction.

The record in suchapparatus is usually formed on a plastic record carrying member, which may be in the form of a discor cylinder or afiexlble loop, guided over appropriate rollers. In the recording operation, th stylus is urged against the record surface while the record is moved linearly; and at the same time, the stylus is moved in a. direction transverse to'the motion of the record,- so as to form a helical-like grooveon the record blank. The stylus is vibrated in accordance with the sound waves to be recorded. Usually this is eflectedby an electric translating device, which converts electrical impulses corresponding to the sound waves impressed on a microphone, into mechanical vibrations. Such translating devices are now wellknown, and require no explanation.

In the reproduction operation, the stylus is caused to follow the previously formed record bottom of the record groove. The vibrations af fled and to operate a generator of sound waves, such as a loud speaker of a telephone receiver. This general system for the reproduction of sound is also wellunderstod, in general and further detailed description is not necessary.

. In order to make it possible to utilize the same apparatus for reproduction as well as for recording, certain features of operation must be considered. For example, in the process 0! recording. the stylus is urged strongly against the rec ord blank, in order to provide a sufficient force for forming the record by a displacement of the material of the.blank. Such a displacement may beeithe'r a definite cutting of a groove, or an em-' bossing inwhich the groove is formed by pressure alone. However, for reproduction purposes, the pressure uponthe stylus is much less, so as to enable it toefollow theundulations without undue friction or wear. t I

It isone'of the objects of this invention to make it possible to adjust the'stylus head in a simple manner. so as to select the pressure actingot). the stylus for optionally performing either the operation of recording or. reproducing.

In a recording operation, the stylu is moved as by a lead screw, in a path transversely of the direction of motion 01' the record blank. The stylus for this operation must be so supported as to provide a rigid support iorthe stylus, thereby causing the recording vibrations oi. the stylus I to be freely effective. In reproduction, however,

the stylus support is soarranged as to have -lat--' eral compliance, so that the stylus is permitted to accommodate itself readily to any slight vagaries of the groove. It is another object of'this invention to provide a simple control for optionally permitting or preventing lateral compliance.

It is still another object of this invention to provide a novel and simple control device by the aid of which the stylus head may be optionally rendered inactive, or conditioned ior either recording or reproduction.

- groove, and the stylus is vibrated in accordance with the undulations formed in the sides or the l feet the translating device, which converts them into electrical impulses, capable of being ampli- Itis usual to provide an amplifier system arranged to amplify the electrical impulses that are used to operate the stylus for recording, or that are produced by the stylus head during reproduction. It-is another object of this invention to vmake it possible automatically to cause the ampliiier system to be properly connected in the stylus mechanism when the mechanism is conditioned for either a recording or a reproducing 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 term in the drawings accompanying and formingpart of the present speci- 'flcatipni This form will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best defined by the appended claims.

Inthe drawings: A

Figure 1 is a view, mainly in longitudinal section, of a phonograph apparatus incorporating the invention;

T Fig. 2 is a front elevatlonas seen in the direction-of arrow of Fig. 1;

Fig. 3 is a fragmentary elevational view taken along the plane 3-4 of Fig. 1;

Figs. 4, 5, 6, '7, 8, 9, 10 and 11 are fragmentary sectional views taken along correspondingly numbered planes of Fig. 1;

Fig. 12 is a horizontal sectional view taken along the plane iii-13 2 of Fig. 1;

Fig. 13 is a fragmentary pictorial view of one of the elements utilized in connection with the apparatus illustrated in Fig. 1.

trated which is capable of carrying a record.

groove. While this record groove carrying mempulses produced by sound vibrations in the microphone circuit are passed to the input side of the amplifier 'l. The output side directly affects and her may take any conventional form it is illustrated in this instance as being made from thin ilexible material as-of cellulose acetate or the like, and capable of passing over an anvil roller 2. The roller 2 may be a driving roller driven from any appropriate source of power so as to move the loop past a stylus 3. The apparatus 5 is a translating device capable of being utilized for either recording or reproduction operations. In the recording position of Fig. 1, the translating device 5 is arranged to convert electrical impulses into vibratory impulses of the stylus 3. These vibratory impulses when the device is in the position of Fig. 1, cause a groove record to be formed on the record carrying member i in a well understood manner.

In the reproducing position illustrated in Fig. 15, the translating device is so arranged that it converts mechanical vibrations of the stylus 3 into electrical impulses. In the inactive position illustrated in Fig. 14 the stylus member 3 is out of contact with the record carrier i and the stylus head is inactive.

Appropriate interlocking mechanism is provided for making it possible to place the stylus 'head into the appropriate positions required op;

tionally-for recording, reproducing or for rendering the apparatus inactive as illustrated in Fig. 14.

Fig. 16 illustrated in diagrammatic fashion how the switching may be eflected for rendering the translating device 5 effective for converting electrical impulses into mechanical vibrations or vice versa.

In. this figurethe stylus head 6 is diagrammatically illustrated as being capable of connection either to the input side or the output side of an amplifier system "I, as by the aid of the

switching devices

3 and 9. With the switches in the position illustrated, sound impulses are first of all converted into electrical impulses as by. a microphone circuit, including microphone lii. These electrical impulses are caused to affect the input side of the amplifier 8 as by the aid of the switch mechanism I l. i The output side of the amplifier is connected by the aid of the switch mechanism 9 to the stylus head 6. In this position therefore It is possible by the aid of the apparatus as hereinafter explained: to cause both

switches

8 and 9 to be opened, rendering the stylus head 6 ineflective, while maintaining switches II and I2 closed. In this position the electrical imthe loud speaker mechanism i3 through the closed switch II. In thi posltion any speech or sound affecting the microphone Hi can be listened to. by the aid of the loud speaker l3.

The stylus 3 and its associated mechanism are so arranged to be advanced in a direction transversely of the recording loop I. This is efiected by the aid of a lead screw l4 (Figs. 1, 3, 8, 14 The axis of this screw is shown as parallel to the axis of the roller 2, and it may be driven by the same source or motion as the roller 2. The lead screw it cooperates with a mutilated nut I5 supported upon a flexible or spring arm It. This spring arm in turn as illustrated most clearly in Figs. 3 and 8, is fastened to an upright arm ii. This arm I! is shown as formed integrally with a carriage l8 appropriately formed as a casting. This carriage i8 has another arm !9 parallel with arm i1 and forming a fork-like structure. The carriage [8 also has a pair of downwardly extended

arms

20 and 2|. The carriage i8 is guided for. movement in a direction parallel to the axis of lead screw it as by the aid of the stationary guide bar 22' passing through the upper ends of the arms l1 and it; as well as by a similar stationary guide bar 23 (Fig. 1) engaged in corresponding slotsin the

arms

20 and 2!. The arms 20 'and ii are both provided with bosses 24 for supporting a restraining strip 25 for maintaining the carriage l8 in proper operative relation to the guide bar 23. The translating device 5 with the stylus 3 is supported upon the frame or carriage l8 and accordingly they are advanced by the coaction of the lead screw it and the mutilated nut 85. For this purpose the right hand end of the device 5 is shown as fastened to the upright arm 26 of a supporting member 27 (Figs. 1, 12, 14 and 15). As shown most clearly in Figs. 1, 8 and 15,

3 is urged by gravity in a counterclockwise direction about the axis of the pivot screws 30, and the stylus 3 is accordingly in operative contact with the record carrying member I.

-This force'of gravity is sufilcient for creating the necessary light pressure upon the stylus 3' when the apparatus is used for reproduction. The manner in which this pressure may be increased for the purpose of recording will be hereinafter described. 4

During the process of reproduction it is also necessary to permit the stylus 3 to have some lateral compliance with relation to the record; that is, it should be free to follow the vagaries of the groove without restraint. For this purpose thesupport 281s shown as being pivoted upon an axis .3l. This is accomplished by the aid of a downwardly extending shank 32 which "is joumaled in the carriage l8. The support 28 is restrained from movement in a direction along the axis 3lby the aid of the shoulder formed by the boss 33 (Fig. .8); andthe washer 34 and nut 35 mounted upon the lower threaded end of the shank 32.

The translating device 5 with its associated parts is shown as protected by a covering or housstructure having depending sides and a depending front portion. This front portion is provided with a slot 31 (Fig. 1) through which the thumb screw 4 may pass. The housing 36 is held rigidly and 39 (Figs. 8 and 12).

in place with relation to the carriage l8 as by the provision of the rearwardly extending portions 38 These portions contact respectively the. inner faces of the upright arms I1 and I9 and may be fastened thereto as by the aid of screws such as 46 (Figs. 1 and 12).

Provisions are made as stated hereinbefore to increase thepressure exerted by the stylus 3 for the purpose of recording. By the aid of the present mechanism not only is the pressure increased; but at the same time the lateral compliance of the device is rendered'ineffective. In other words, the support 28 is restrained against angular movement with respect to its For accomplishing this purpose a weight mem-, ber 4| is utilized (Figs. 1 and 6). This weight member hasan upper portion extending across the translating device 5 and has two weighted iii.

weight 4| is effective. When the handle 66 is am 55 to maintain the shaft 52 in any of a

numsides

42 and 43 embracing the device 5. As shown most clearly in Figs. 1 and 12 this weight 4| is provided with rearwardly extending parallel arms.

face of the weight 4| is provided with a tapered recess 41 adapted to receive the tapered'proiection 46 provided on top of the device 5. The aperture 41 and the projection 48 have a substantial length in a direction longitudinal of the weight as illustrated most clearly in Figs. 1 and 15. Acordinglywhen the weighted member 4| is in the engaged position of Fig. l, the engagement ofprojection 41 in the recess 48 restrains lateral movement of the device 5 with respect to the cariage l8. Accordingly lateral compliance is eliminated.

When it is desired to place the apparatus in condition for reproduction as illustrated in' Fig. 15, the weight member 4| is lifted free of the device 5. The mechanism whereby this is accomplished will now be described.

In order to form a supplemental. guide for the engaging and disengaging movement of the right hand end in a standard 53 (Figs. 1, 14 and.

). The cam 5| is shown as provided with an integral hub 54 that is Journaled inanother standard 55 adjacent the left hand end of the apparatus. Axial movement of the shaft 52 is prevented by the aid of a collar 56 adjacent the,

' right hand surface of the standard 53, and by the aid of a collar 51 adjacent the left hand surface of standard 55. Collar 51 may be provided with a handle 58 (Figs. 1, ;2, 3 and 14). By the aid of this handle the angular position of the shaft 52 may be adjustedso as to move the cam 6| to the inactive position of Fig. 6. In this position the ing point 61.

her of angular 'positions. The manner .in which this is accomplished is shown most clearly. in Figs. 1 and 7. p

The hub 54 is provided with a series of arcuate depressions 59, 66 and Bi having a space of 96 Adapted to cooperate with any one of these depressions is a' ball restraint 62 movable in a vertical aperture 63. The ball restraint 62 is urged as by a compression spring 64 downwardly into engaging position. The compression spring is held in place by headless screw 65 engaging the upper threaded portion of the bore 63. In the position of Figs. 1 and-6 with the weight in operative position, the ball 6'2 is in engagement with therecess 60. When the handle 58 is rotated through 180 in a counterclockwise-direction to the position of Fig. 2, the ball 62 cooperates with recess 59. In this way the shaft 52 may be maintained resiliently in either of. its two positions. The intermediate recess 60' is utilized in a manner to be hereinafter described, when the stylus 3 to be lifted clear of the record member-i (Fig. 14).-

In order to make it possible to lift the stylus 3 and its associated translating device Bout of operative relation with respect to the record member, as shown in Fig. 14, ,a mechanism is utilized that is illustrated most clearly in Figs. 1, 5 and 14. For this purpose the swinging support 21 isprovided at its right hand end with an upright member 66. This upright member as shown most clearly in Fig. 5 is provided with an upward taper- When this point. is'urged downwardly or in a clockwise direction. with respect to the axis of the support 21, the device 5 and the stylus 3 are caused to move upwardly to the position of Fig. 14. For accomplishing this movement use. is made of a bar 68. This bar 68 is provided at its right hand free end with a tapered recess 69 adapted to cooperate with the point 61. In the position of Figs. 1 and 15, this bar 68 is out of contact with thepoint 61.

The bar 68 is pivotally mounted by the aid of the ears 16 (Fig. 3). This pivotal mounting is adjacent the left hand end of the bar 66. Normally the bar 68 is urged upwardly so as to clear th point 61 as by the aid of a U-shaped leaf spring 1| interposed between the lower side of' the bar 66 and the upper surface of the housmg as. 6

When it is desired to depress the bar 68 to the position of Fig. 14, the shaft 52 is rotated until the ball restraint 62 cooperates with the intermediate recess 66. This rotation in a counterclockwise direction from'that shown in .l'ig. 2

' causes corresponding rotation of a cam I2 mounted on the right hand end of shaft 22. This cam 12 is shown to best advantage in Figs. 8 and 13. In the active position, the raised portion of one side of the cam 12 depresses the bar 66, and the stylus head mechanism including the translating device 5 and stylus 3 are tilted upwardly to the position of Fig. 14. It is noted that when either a recording or reproducing position is obtained by rotation of the shaft 22 through an angle of 90 in either direction from the inactive position of Fig. 14, this cam 12 is rendered inactive; therefore for either of these two ex- A treme positions (illustrated in Figs. 1 and '15)- the stylus 8 is maintained in operative relation This cam'projection 13 causes disengagement of the mutilated nut l5 from the lead screw M. For this purpose the resilient arm [6 which supports the nut is is rovided with a depending portion 14' in the path of the cam portion 13. Whenthe shaft 22.is rotated in such a direction as to lift the stylus 3 from a record carrying member I, this cam 13 engages behind the portion 14 and flexes the arm It to the position indicated in Fig. 14. In this position therefore the stylus head is disengaged from the driving mechanism;

It may also be convenient to operate the switch devices H, il, 9 and I2 of Fig. 16 in accordance with the movement of the shaft 22 tothe cor-' responding positions.

- The switching means in this case is shown as comprising a series of eight pairs of spring fingers supported upon one wall of a casing", by the aid of a series of insulation strips. This casing 16 is made from sheet metal. As shown most clearly in Figs. 3 and 4, it is provided with the side flanges 11 by the aid of which it may be attached to the top of the housing 36.

The insulation material supporting the contact fingers (Fig. 4) comprise the insulation bars 15, 15' and I8. Since the pairs of spring fingers are quitesimilar in structure, the spring fingers adjacent the left hand portion of the casing 16 only need be described in,detail. These are shown in Fig. 4. Thus the spring fingers l9 and 19 are positioned one over the other; and spaced apart by the aid of the insulation bar 15'. In their free position the contact points 80 and 81 carried by the fingers are disengaged. The next adjacent pair of spring flowers 82 are entirely similar to the spring. fingers I9 and 19'. .These two pairs of spring fingers 19-19, and 82 correspond to the switching means ll of Fig. 16. They are controlled by a common cam 83 mounted on shaft 52. This cam 83v is of such configuration that the switching means ll' remains closed for either the recording position or for the position corresponding to inactivity of the stylus 3. However, for reproduction purposes, it is apparent that a cam rotation of 180, from the position of Fig. 4 will permit the spring fingers l9 and I9 and the corresponding pair of springfingers 82 to separate, and the circuit is broken at the switching means H. Accordingly the microphone circuit is active at tion is desired.

In the recording positionillustrated in Fig 16,

the switch mechanism 9 corresponding to the two pairs ofspring fingers 84 of Fig. 1 are maintained 7, These spring fingers make contact when the apparatusisiplaced in reproducing positlon'or when the stylus 3 is lifted out of engagement with the i I flexible record carrying member I. This is accomplished by the aid of the cam 890i the configuration shown in Fig. 10, and mounted on shaft 22.

The various connections to the spring fingers are accomplished by the aid of a cable 90 (Figs.

1, 4 and 8) held asby the aid of a clip 9| mount- 1 ed on the upright arm ll. Two leads from this cable extend as shown in Fig. 1 to the trans,- lating device 5; Other leads connect to the corresponding appropriately formed ears provided on-the upper ends of the spring fingers.

- From the,foregoing it is seen that the adjustment of the apparatus for recording, reproducing or listening in-is effectively accomplished by appropriate annular rotation of shaft 52 and the corresponding mechanical interlocks that cooperate with the translating device 5 and the switching mechanisms.

What is'claimed is:

1. In a. phonograph apparatus, a stylus head, means for mounting said head inoperative relation we member capable of carrying a record groove, and permitting relative free movement in a direction lateral of the record'groove, and a movable weight structure adapted optionallyto be free of the head, so that the head may operate as a reproducer, or to cooperate with the head to increase the stylus pressurev as well as to restrain the head from lateral motion with respect to the mounting means, so that'the head may operate as'a recorder, I V

2. In a phonograph apparatus, a stylus head, a pivot structure for the head to permit motion of the head in a direction toward and from a memas for permitting angular movementof the head i in a direction lateral ot-the record groove, a movable weight member adapted optionally to be free of the head, so that the head may operate as a reproducer, or to cooperate with the'head to increase the stylus pressure, and means for guidall times except when reproducing the movement of the weight member in such manner that when the weight member is effective to increase the pressure, said guiding means cooperates to restrain lateral movement of the head, so that the head may operate as a recorder 3. In a phonograph apparatus, a stylus head, a pivot structure for the head to permit motion of the head in a direction toward and from a member capable of carrying a record groove, as well as for permitting angular movement ofthe head in a direction lateral of the record groove, a weight member cooperating with said head, said weight member and head having a detachable connection formed by a projection and a groove, and means for movably mounting said weight to engage ordisengage said connection, saidconnection when established serving also to restrain lateral motion of said head.

4. In a phonograph apparatus, a stylus head, a lead screw for moving the head, a mutilated nut engaging the screw, a leaf spring support for the nut, a bearing support for the head, and a cam device for angularly moving the head into inactive position, as well as for urging the leaf spring support to move the put out of engagement with the screw.

5. In a-phonograph apparatus, a stylus head movable into active or inactive position, a device for increasing the-pressure upon the stylus head,

cam means for controlling position of' the stylusthe stylus head, cam means 6. In a phonograph apparatus, a stylus head movable into active or inactive position, disconnectible means for traversing the head in relation to a member capable of carrying a record groove, cam means for controlling the position of the stylus head, cam means for disconnecting the traversing means, and a common 'angularly adjustable means upon which both said cam means are mounted.

7. In a phonograph apparatus, a stylus head movable into active or inactive position, disconnectible means for traversing the head in relation to a member-capable of carrying a record groove, means for optionally increasing the pres-- sure upon the head,cam means for controlling the position of the stylus head, cam means for disconnecting the'traversing means, cam means for controlling the pressure increasing means, and a common angularly adjustable means upon which all said cam means are mounted.

8. In a phonograph apparatus, a stylus head movable into active or inactive position, disconnectible means for traversing the head in relation to a member capable of carryin a record groove, means for optionally increasing the pressure upon the head, means cooperating with the head and the pressure increasing means for restraining the stylus head against free lateral movement when the pressure increasing means is active,; cam means for controlling the position oi the stylus head, cam means for disconnecting the traversing means, cam means for controlling the-pressure increasing means, and a common angularly adjustable means upon which all said cam means are mounted. r

9. In a phonograph apparatus,a stylus head movable into active or inactive position, a device for increasing the pressureupon the stylus head, cam means for controlling position of the stylus head, cam means for controlling the pressure increasing device, a common means for operating both of said cam means, and amplifier control switching means also operated by said common means for establishing appropriate connections corresponding to the angular position of said plurality of cam means.

10. In a phonograph apparatus, a stylus head movable into active or inactive position, disconnectible means for traversing the head in rela tion to a member capable of carrying a, record movable into active or inactive position, disconnectible means for traversing the head in relation to a member capable of carrying a record groove, means for optionally increasing the pressure upon the head, means cooperating with the head and the pressure increasing means for re straining the stylus head against free lateral movement when the pressure increasing means is active, cam means for disconnecting the traversing means, cam means for controlling the pressure increasing means, a common angularly adjustable means upon which all said cam means are mounted, and amplifier control switching means also operated by said common means for establishing appropriate connections corresponding to the angular position of said plurality of cam means.

13. In a phonograph apparatus, a stylus head, disconnectible means for traversing said head in relation to a member capable of carrying a record groove, means for optionally conditioning the head either for recording or reproduction, said conditioning means including a device for restraining lateral motion of the head, means for disconnecting the traversing means, and a common mechanism for controlling the disconnecti ble means and the conditioning means, comprising an angularly adjustable shaft, having definite angular positions corresponding to the control functions.

14. In a phonograph apparatus, a stylus head, disconnectible means for traversing said head in relation to a member capable of carrying a rec- 0rd groove, means for optionally conditioning the head'either for recording or reproduction, said conditioning means including a device for restraining lateral motionof the head, means for disconnecting the traversing'means, and a'common mechanism for controlling the disconnectible means and the conditioning means, comprising an angularly adjustable shaft, having three angular positions, corresponding respectively to a recording position, a reproducing position, and an inactive position.

15. In'a phonograph apparatus, a stylus head movable into active or inactive position, a device groove, cam means for controlling the position of for disconnecting the traversing means, able means upon which both saidcam means are mounted, and amplifier control switching means a common angularly adjustalso operated by said common means for establishing appropriate connections corresponding to the angular position of said plurality of cam means, r

11. In a phonograph apparatus, a stylus "head movable into active or inactive position, disconnectible means for traversing the head in relation to a memberlcapable of carrying a record groove, means for optionally increasing the pressure upon the head, cam means for controlling the position of the stylus head,'cam means for disconnecting the traversing, means, cam means for controlling the pressure increasing means, a common angularly adjustable means upon which all said cam means are mounted, and amplifier control switching means also operated by said common means for establishing appropriate connections corresponding to the angular said plurality of cam means.

12. In a phonograph apparatus, a stylus head forincreasing the pressure upon the stylus head, means for controlling the position of the stylus head, means for controlling the pressure increasing device, and a. common mean for operating both of said means.

16. In a phonograph apparatus, a stylus head capable of operating optionally as a recording head or a reproducing head, means ror traversing the head with respect to a record, pivotal means adapted to provide lateral complianc for the head, a pivoted weight adapted to engage thehead to restrain the head about the pivotal means and to apply a force of gravity for recording purposes, and means for lifting the weight out of engagement with the head.

17. In a phonograph apparatus, a stylus head capable of operating optionally as a recording head or a reproducing head, means for traversing the head with respect to a record, pivotal means adapted to provide lateral compliance for the head, a pivoted weight adapted to engage the head to restrain the head about the pivotal means position of v and to apply a. force-of gravity for recording purposes, an extension connected to the weight, and a pivoted arm adapted to engage said extension to move the weight out of. engagement with the head.

18. In a phonograph apparatus, a stylus head capable of operating optionally a arecording head or a reproducing-head, a carriage for the head, a lead screw for traversing the headt-a multilated nut adapted to be placed into and out of engagement with the screw and carried by the carriage, a weight mounted on the carriage and movable optionally to engage the head for recording purposes, and to be disengaged from the head for reproducing purposes, an angularly adjustable shaft;- mounted, on the carriage and having an axis-transverse to the screw, means.

, head or'a reproducinghead, a carriage for the 'headaa lead screw for traversing'the head, a mutilated nut adapted to be placed into and out of engagement with the screw and carried by the carriage, a weight mounted on the carriage and movable optionally to engage the head for recording purposes, and to be disengaged from the head for reproducing purposes, an angularly adjustable shaft mounted on the carriage and having an axis transverse to the screw, means operated. by .the shaft for causing the nut to move into and out-of engagement with the screw, and means operated by the shaft for lifting the weight out of engagement with the head, the angular position orthe shaft determining the operation of said nut and of said weight.

A. ALBERT W. DE SAR'I', SR.