US2344646A - Sound recording apparatus - Google Patents

Description

March 21, 1944. c. D. SHRADER 2,344,646

SOUND RECORDING APPARATUS Filed Nov. 28, 1941 '7 Sheets-Sheet 1 \NSULATlON INVENTOR CHARLES D. SHRADEQ ENEY.

INSULATION March 21, 1944. c, SHRADER SOUND RECORDING APPARATUS Filed Nov. 28, 1941 7 Sheets-Sheet 2 w T N E V N CHAQLES D. S HEADEQ N UHHH BYKJU A T QNEY.

March v21 1944. c. D. SHRADER 2,344,646

SOUND RECORDING APPARATUS Filed Nov. 28, 1941 7 Sheets-Sheet 4 as 4 --e23 ENV EN TOE CHARLES a SHEADER 14% HEY. mad? March 21, 1944. c. D. SHRADER SOUND RECORDING APPARATUS Filed Nov. 28, 1941 7 Sheets-Sheet 5 INSULATION N v m m d M m U RR S N 7 OH Y nr nll m m ED D H a V. .O M 7 Mm n M 2 m m H C Y m -w e B Z L m2 M WE m DW 5 W 0L d m mm MW WMA 7W 0 7%. mw E m; H4 I Z I WW .I MR .L NW 2 am 0L 0 7 =5 2 m (Z March 21, 1944. c. D. SHRADER SOUND RECORDING APPARATUS Filed Nov. 28, 1941 '7 Sheets-Sheet 6 INSULAT\ON INVENTOR CHARLES D. SHQADEQ W/WQQ m A'TTO :2 N EV.

March 21, 1944. CD. SHRADER 2,344,646

SOUND RECORDING APPARATUS \NVENTOFZ CHARLES DSHEADEE OQNEY Patented Mar. 21, 1944 UNITED STATES PATENT or-Pica 2,344,646 SOUND RECORDING APPARATUS Charles D. Shrader, Oakland, Calif. Application November 28, 1941, Serial No. 420,847

(Cl. it's-100.4)

Claims.

This invention relates to mechanism for producing permanent sound records and reproducing sound from said records, and is a division of my prior application Serial No. 307,352, filed December 4, 1939.

. 'record, a sleeve of low-cost flexible film.

Still another object of the invention is to provide, in a sound recorder using a cylindrical drum, novel drive means for the drum which is contained substantially wholly within the latter.

Yet another object of the invention is to provide novel mounting means for the recording and reproducing devices and also novel means for conducting electric currents to and from, the recording and reproducing devices.

The invention possesses other objects and features of advantage, some of which, together with the foregoing, will be specifically'set'forth in the detailed description of the invention hereunto annexed. It is to he understood that the invention is not to be limited to the specific form thereof herein shown and described as various other embodiments thereof may be employed within thescope of the appended claims.

Referring to the drawings:

' Figure 1 is a top plan view of the complete recorder and reproducer. A portion of the view is broken away and shown in section so as to I more clearly disclose the internal construction.

Figure 2 is a horizontal sectional view of the structure shown in Figure 1. The view is taken substantially along the plane indicated by the line 2-2 of Figure 3.

Figure 3 is a vertical sectional view of the recorder and reproducer. The view is taken sub-- stantially along the plane indicated by the line 3-4 of Figure 2.

Figure 4 is an end elevational view of the apparatus.

Figure 5 is a fragmental vertical sectional view of the speed change mechanism. The plane in which the view is taken is indicated by the line 5-! of Figure 2.

Figure 6 is a transverse vertical sectional view of the apparatus. The plane of section is indicated by the line 5-6 of Figure 2.

Figure 7 is a schematic wiring diagram showing the electrical circuits associated with theapparatus.

Figure 8 is'a transverse vertical sectional view of the apparatus. The plane of section is indicated by the line 88 of Figure 2.

Figure 9 is a transverse vertical sectional view of the apparatus. The plane of section'is indicated, by the line 9-9 of Figure 2.

Figure 10 is a transverse vertical sectional view of the apparatus showing the recording and reproducing heads in their operative positions. The plane in which the view is taken is indicated by the line Ill-Ill of Figure 1.

V Figure 11 is a view, similar to Figure 10, showing the recording and reproducing heads in their respective inoperative positions.

In detail, the apparatus comprises a base plate I! having secured to and rising from one transverse end thereof an end plate l3. Angle bars ll, secured to the opposite longitudinal edges of the base plate l2, and at one end. to the end plate l3, are'provlded for lending rigidity to the base plate and vertical stability to the end plate. As is best shown in Figure 3, a motor support bracket composed of contiguous integrally connected bars I8 is spaced'irom and parallels the base plate l2, both bars at one end :being bent upwardly to form a support II -for tubular stub shaft l8 which is secured in a suitable aperture formed in the support I! by a nut I! which en gages the threaded shank 2| of the stub shaft.

The opposite ends of the bars l8 are each bent in opposite directions, at right angles to the bars. to form flanges 22 and 23 having apertures formed therein axially alined with correspondingapertures formed in the end plate II and through which pass bolts 24 which secure the motor support bracket to the end plate. Ribs 28 are preferably welded to the bars II at their several angular bends so as to stiflen the bars Joumaled on the stub shaft i8 is a sleeve 21 the arms 3 inand is provided with integral bosses 33 which are axially bored and receive clamp bolts 34 by means of which the hubs 29 are clamped to and fixed for rotation with the sleeve 21. The outer end of each of the spider arms 3i is attached by a screw 36 to a lug 31 formed integrally with and extending radially from the inner periphery of a cylindrical drum 38 which is axially concentric with the stub shaft 18 and is rotatable about the said stub shaft axis. The outer periphery of the drum 38 is. as wi l be seen upon careful examination of Fi ure 1, slightly tapered longitudinally sothat when the tubular film record 39 is telescoped, over and pushed toward the enlarged end of the drum a secure frictional engagement between the record andthe drum will obtain. The smaller end of the drum is preferably provided with a. bevel 4| which facilitates starting the tubular record on to the drum and the larger end of the latter is fitted with a flange 42 against which one edge of the record may abut.

Means is provided for rotating the drum and the record mounted thereon. As will best be seen in Figure 3. the motor support bracket is provided with a pair of spaced radially elongated apertures 43 in which are positioned studs 44 each being attached to its upper end to the ends of a loop 48 of spring sheet material. The lower end of each stud is provided with a diametrically reduced shank 41 which passes through an aperture formed in a slide 48, the stud being secured to the slide by means of a nut 49 threadedly engaged with the stud shank 41. The arrangement of the parts is such that the assembly of the loop 48, the studs 44. and the slide 48, may be moved back and forth longitudinally of the motor support bracket within the limits of the elongation of the apertures 43. Mounted by screws 'on the loop 46 is a m tor 2 hav g attached to one end thereof a housing 53 containing a worm reduction gear which drives at low speed. a transversely disposed shaft 54 which extends from the housing 53. The shaft 54 is rovided w h a lon itudinally extendin keyway 56 for slidabl receiving a key fixed within a friction wheel 51 which may be moved. axially, longitudinally of the shaft. Secured. by screws 58, to lugs 59 formed with :and extending radially inwardly from the inner periphery of the drum 38, is a drive ring 61 having in one face thereof an annular groove 62 in which is preferably cemented or otherwise secured. an annulus 63 of rubber or other such resilient material. The friction wheel 51 is positioned to engage the surface of the annulus 63 to effect a driving connection therebetween. When the motor 52 is unning rotati n of the shaft 54 will rotate the friction wheel- 51 and will thereby impart rotation to the drum 38 and the record 39.

Means is provided for varying the effective ratio between the motor and the drum so that the rotational speed of the latter may be adjustably varied while maintaining c nstant speed in the motor. The friction wheel 51 is provided with an axial extension 84 having therein a peripheral groove 66 and the bore of the wheel is provided with a plurality of axially spaced peripheral rooves 61. In a recess 68. drilled radially into the shaft 54. is a spring 69 which engages and presses a latch ball 1i into one of the grooves 61. It will be seen that if the friction wheel is moved axially along the shaft 54 the latch ball 1| will be engaged with successive of the grooves 81 thus positioning the friction wheel at different radial distances from the rotational center of the annulus 63 which will, of course, change the r0- tational ratio between the shaft 54 and the drum 38. It will of course be obvious that a greater number of positioning grooves 61 may be provided in the friction wheel 51 sothat a larger range of speed changes is made possible; a fewer number being shown so as to simplify the drawings. Means is provided, extending exteriorly of the apparatus, for moving the friction wheel between selected positions. Formed in a boss 12, extending from the inner surface of the end plate I3, is a guide aperture 13 in which is slidably mounted a shift rod 14 having at its outer end a,

grip knob 16 and at its inner end, Figure 5, a hub 11 from which extends a radial arm 18 having at its extreme end a semi-circular yoke 19 which is curved complementarily to the peripheral groove 66 of the friction wheel extension 64. The length of the arm 18 is such that, when the grip knob 16 is rotated, the yoke 19 may be moved into engagement with the groove 66, as shown by the dotted lines 8| of Figure 5, or to a position out of engagement with the groove as shown by the solid lines of the aforementioned figure of the drawings. A plurality of axially spaced peripheral grooves 82, similar in number and spacing to the grooves 61 of the friction wheel, are provided in the shift rod 14 which are successively engageable with a spring pressed latch ball 83 which frictionally fixes both the axial and rotational positions of the shift rod. Thus the yoke 19 may be held out of engagement with the friction wheel at all times except when the drive ratio is being changed so that no unwanted vibrations will be transmitted from the supporting frame to the drum and the record. The vibrations transmitted through the motor 52 and the rotational drive will be negligible since the motor is resiliently mounted by the spring loop 46 and the drive connection between the friction wheel 51 and the drum 38 is through the resilient rubber annulus 63. While for purposes of simplicity in the drawings, the motor 52 has been shown as mounted on the leaf spring loop 46 it will be obvious that this mounting may be effected through a block of rubber or through any other known cushioning means without departing from the spirit of the invention.

Means is provided for varying the pressure of the friction wheel 51 against the surface of the annulus 63 so that different degrees of traction between the parts may be effected. Journaled in an aperture 84 in the end plate I3 is an adjustment shaft 85 fitted at its outer end with a rotating knob 81 and having a collar 88 secured thereto adjacent the inner surface of the end plate so that the shaft is restrained against axial movement but is free to be rotated. The extreme inner end of the shaft 86 is threaded to engage mating threads formed in a boss 89 formed integrally with one of the motor support bracket bars l6. Since, as was explained above, the motor is slidable axially together with its mounting in the elongated apertures 43 of the motor support bracket, it will be seen that by rotating the knob 81 the threaded connection between the shaft 86 and the motor support will cause the friction wheel 51 to be urged vn'th more or less pressure against the face of th annulus 83 thus varying the degree of traction between the contacting parts.

Means is provided for inscribing a sound groove in the record 39, and means is also provided for permitting reproduction 33 of any portion of said sound recording either while a recording is in progress or as a separate operation I a setscrew I99.

after the recording has been completed. As will be most clearly seen in Figure 1, a pair of cylindrical guide rods BI and Marc disposed in spaced relation overlying the drum and the record 39 and are each secured by nutsv 93, in insulating bushings 94 provided in the end plate I3. The

other end of each of the guide rods is secured by nuts 96 in a spacer bar 91 of insulating material, preferably Bakelite, adjacent the opposite end of the drum. Referring now to Figure 10, a metallic bushing 92 is mounted on and slidable along the guide rod 9| and is preferably pressed into an insulating sleeve 99. A pair of parallel frame plates I III are secured to opposite ends of the insulating sleeve 99 and are, by the latter, electrically insulated from the guide rod 9|. Pivotally mounted on a shaft I92, which has its opposite ends fixed in the respective frame plates I9I, is an arm I93 having an enlarged weighted integral head I94. An electro-magnetically operated recording head I99 is provided having at one end of its armature a chuck I9'I in which a suitable pointed stylus I98 may be secured by Extending from the recording head is a pair of lugs III, which engage pivot pins II2 carried by the weighted head I94 so that the recording head is pivotally mounted on the head I94 and an additional pair of lugs II3 between which a bearingiblock H4 is pivotally mounted. Another pair of lugs II6 rises from the arm I93 between which a nut III is pivoted and an adjusting screw I I8 having threads thereon, which engage mating threads formed in the bore of the pivoted nut III, is'provided at its end with a diametrically reduced shank II9 which is journaled in the bore of the pivoted bearing block II4. A collar I2I, pinned to the end of the shank H9 and engaging the face of,

the bearing block H4, is for the purpose of retainingthe shank in the bearing block. A knurled handwheel I22, which is pinned to the shaft II8, provides means facilitating rotation of the shaft. It will be seen that when the shaft II 8 is rotated, it will be advanced axially thereby causing pivotal movement of the recording head I96 about the axis of the pivot pins. II2. This causes the stylus I98 to assume different angular positions with respect to the surface of the record film 39. quite important if clearly reproducing recordings are to be made. In order to regulate and maintain constant the depth that the stylus may inscribe the sound groove into the surface of the record, a setscrew I23 is provided in the arm I93 the lower end of which abuts against the insulating sleeve 99. It will be seen that by rotating the setscrew in opposite directions the entire arm I93 and consequently the point of the stylus I98 may be raised or lowered; thus limiting the depth that the weighted end I94 of the arm I93 may force the stylus into the surface of the record. It will also be seen that the arm I93 and the recording head may be pivotally moved about the axis of the pivot pin I92 so that the recording head may be lifted clear enough to allow inspection or replacement of the stylus.

Slidably mounted on the guide rod 92, is a metallic bushing I24 surrounded by an insulating sleeve I26. A pair of parallel frame plates I21 are secured to opposite ends of the insulating sleeve I26 and are also joined together by a metallic crossmember I29 and by a metallic bar I29 which is extended to form a handle I3I.

This angular setting of the stylus is ill Both the cross-member I29 and the bar I29 may be welded or brazed to the frame plates I21 or attached in any other suitable manner. Pivotally mounted. by means of a pivot screw I32, on the cross member I28 is a swivel plate I33 having an integral pair of extension arms I34 fitted with pivot pins I36 upon which a reproducing head I3! is journaled. The head I31 contains a signal generator which may be either an electro-magnetic device, or'a piezo crystal, actuated by vibrations picked up by the stylus I38 which is capable of tracking in the sound grooves created by the recorder stylus I98. The stylus I39, being held in the chuck I39 by the setscrew I4I, may be removed for replacement. It will be observed that the pivots I32 and I36 provide a universal mounting for the reproducing head I31 so that it is free to move in any direction to follow irregularities in the surface of the record film 39.

Means is provided, common to both the recording and reproducing heads for advancing the heads at a predetermined rate axially of the drum 38 so that the stylus I99 of the recording head may inscribe a helical sound groove of uniform pitch in the record film 39, and the stylus I38 of the reproducing head will track correctly in the groove without causing any undue wear on the sides of the latter. Positioned for rotation intermediate and paralleling the guide rods 9I and 92 is a threaded lead screw I42 one end of which is provided with a shank I43 journaled in a metallic bushing I44 secured in an aperture, formed in the spacer bar 91, by a nut I46, and the other end of which is provided with a longer shank I41 journaled in and extending beyond a bushing I49 preferably pressed into an aperture provided in the end plate I3. Referring again to Figure 10, it will be seen that the frame plates I9I, of the recording head mounting, are each extended to positions overlying the leadscrew I42 and are integrally connected with a quarter-nut I49 which is provided with threads mating with those of the leadscrew. When the quarter-nut I49 is in mesh with the threads of the leadscrew, and the latter is rotated, it will be seen that the recording head and its mounting will be moved axially along the guide rod 9I at a rate dependent upon the pitch of the threads of the leadscrew and the latters speed of rotation. The bar I29, associated with the reproducing head mounting, is provided with an extension I5I upon which is securely mounted a fractional nut I52 similar to the quarter-nut I49, and provided with threads matching and engageable with those of the leadscrew so that upon rotation of the latter the reproducing head and its mounting may be advanced axially of the guide rod 92 at a rate equalling the rate of travel of the recording head. It may be noted here that the construction of the nuts, which drive the recording and reproducing heads, allows the heads to be shifted pastand without interference from each other and also allows the reproducing stylus I38 to track in the sound groove closely adjacent to the recording stylus I98. This permits practically immediate playback of the sound groove as it is being recorded, there being actually, as will be seen in Figure 19, only a small fraction of a second difference between the time that the point of contact of the recording stylus with the sound groove reaches the reproducing stylus.

Means is provided connecting the leadscrew 4 K with, and for rotation by, the motor 62 so that the rotation of the leadscrew will be synchronized with that of the drum 38 and the record film 39. Referring to Figure 3, it will be seen that the tubular stub shaft I8 is 'ilttedat one end with a plain bushing I53 and at the other endwith a bushing I54 having a peripheral flange I56 which, in contacting an end of the sleeve 21, acts as a thrust bearing [to absorb the thrust of the friction wheel 51; against the face of the rubber annulus 63. The bearings I53 and I54 also serve as journals-for a shaft I51 which, at one end, is fitted with a collar I58, retain'ed on the shaft by a setsorew I59, provided with a radial arm I6I terminating in anangularly directed stem I62 which is seated in a drilled recess I63formed in the hub 29 of one of 'thedrum-supporting spiders. Fixed to the opposite end of the shaft I51 is a pinion I64. ,An. intermediateshaft I66, at one end passes through andextends beyond a journal provided therefor in the end plate I3, and, at the other end, is journaled in an aperture formed in a wing extension I61 of one of the bars I6 forming the support I1. A gear- I68 fixedly mounted on the said other end of the shaft I66, is in mesh with the pinion I64. A sprocket I69, fixed to the end of the shaft I66, which extends beyond the ,outer face of the end plate I3, is in mesh with an endless chain I1 I which also meshes with another sprocket I12 secured, by means of a setscrew I13, on the shank I41 of the leadscrew I42. It will be seenthat, when the drum 38 is rotated by the -moto'r52, the ,connectionof the shaft I51 with thedrum-spider, through the arm I6I will effect rotation of the shaft 'I 51 thus imparting, through thegears. I64 and I68, rotation to the intermediate shaft I66, and to the leadscrew I42 through the sprocke J69 and I12 through the chain I1 I. en that, since the rotational ratio ma e drum and the leadscrew I42 may be altered, to provide a greater or lesser spacing of the -:heli,c a'l sound groove on the record film, is by whang lng'the ratio of the gears I64 and* I68 or by gone of .;thej,spfockets I69 or I12 larger L'lh aIrangement and propor- -the-drawlngs give quite satise drum being rotated at a speed otgaboutaaqr.Miwnicn gives the so thread per fl-lnchgleadscrew a rotational speed of 1.6 R. P. M. r therebyproducing a sound groove having 150 convolutions to "the inch or a linear pitch of .006.

. It will ofbdurs'd be understood that the proportions fgiven-jabpve' are purely exemplary since,

when a signal of extraordinary volume is used to actuatethe'recording head, a-coarser spacing between adja'cent convolutions of the sound groove is necessary in order to prevent lateral overlapping or relative distortion of the convolutions.

Means is provided which permits selective raising or lowering of either the recording head or the reproducing head so that either one, or both, may be rendered active or inactive as desired to allow for recording alone, reproduction alone, or simultaneous recording and reproduction. Disposed in spaced parallelrelation to theguide rod 9| and journaied at its ends, respectively, in the end plate I3 and the spacer bar 91, is a shaft I14 keyed to the end of which, adjacent the spacer bar and as is best shownin Figure 8, is a hub I1r6 carrying an arm I11 extending transversely over the guide rod 9| and the leadscrew I42 and terminating in an eye I18 in which is secured one end of a lift rod I19 which extends in spaced 2,344,646 r c I parallel relation to the leadscrew. To the other 7 end plate, a lever I83 having rising therefrom,

intermediate its ends, a stem I84 which has a terminal eye I86 in which the other end ofthe lift rod I19 is secured. Referring now to Figure 10, it will be seen that the lift rod I19 passes through elongated apertures formed in extensions I88 of the recording head frame plates I9I so that the lift rod is operatively connected with the recording head mounting. It will be seen that upon lifting the projecting handle I89 of the lever I83 the shaft I14 will be rotated thereby causing elevation of the lift rod I19 and rotary movement of the entire recording head mounting about its pivotal axis, which is the axis of the guide rod 9|, so as to disengage the quarter-nut I49 from the leadscrew I42. As shown in Figure ,1, an aper-v ture is formed in the lever I63, just inside of the edge of the end plate I3, into which is pressed a sleeve I9I containing a spring I92 which urges a latch ball I83 into one of a pair of depressions I94, best indicated in Figure 4. By means of this construction the recording head may be releasably maintained in elevated and inoperative position as shown in Figure 11. Returning again to Figure 10, it will be seen that a drilledy hole I96, passing through the bar I29, the insulating sleeve I26 and the metallic bushing I24, is provided which axially intersects the axis of the guide rod 92. Slidably mounted in the hold I96 is a cylindrical latch pin I91, constructed of insulating material such as Bakelite or the like wear-resisting material, having a rounded lower end which may engage in a shallow groove I96 formed in and extending axially along the surface of the guide rod 92. A leaf spring I99 secured by screws 20I to the bar. I29 bears against the upper end of the latch pin I91 so as to resiliently urge the latter into engagement with the groove I98. It will be seen, from Figure 10, that when the reproducing head I 31 is in itsloweredv or operative position, the latch pin I96wil1 be rotationally offset with respect to the groove I98 and that, as seen in Figure 11, when the handle I3I is lifted the latch pin will be moved into alinement with the groove and will snap thereinto, urged by the spring I99,to-hold the reproducing head mounting in elevated position until released. In order to cause the horizontally pivoted reproducing head to follow its mounting, when the latter is elevated, so that the stylus I38 will be held clear of the record film 39, a support spring 292, secured by one or more screws 293 to the reproducing head, is provided which engages the swivel plate I 33 as the reproducing head mounting is lifted, as seen in Figure 11, soas to limit the downward movement of the head'about the axis of the pivots I39. f

It will be noted that the. guide rods 9! and 92 are each completely electrically insulated from the majority of the metallic parts of .the apparatus by means of the insulating bushings 94, the insulating spacer bar 91, and the respective insulating sleeves 99 and I 26. This is doneso as to utilize the guide rods 9| and 92 as current conductors for supplying the recording head with sound modulated actuating current and for conveying the generated sound translation current from the reproducing head. As will be clearly seen in Figure 7, one terminal of the actuating coil 204 of the recording head connected by which slidably contacts the guide rod 9 I, and the other terminal of the coil is connected by a lead 201 with the recording head mounting or the quarter-nut I49 which releasably engages the leadscrew I42. One terminal of the reproducing current generator which, "for convenience, has been indicated as a coil 208, is connected by a lead 209 with the metallic bushing I24, which is in slidable contact with the guide rod 92, and the other terminal thereof is connected, by a lead 2I I with the reproducer head mounting or fractional nut I52. A recording amplifier 2I2 which is fed from a microphone, or otherjsuch input device '2I3, has one output lead 2 connected'with the guide rod III, and an output amplifier 2; which drives a loudspeaker 2I1, or similar translation device, has one input lead 2I8 connected with the guide rod 92.' The other output lead 2I9 of the recording amplifier and the other input lead 22I are joined and connected by a common lead 222 with the main body of the apparatus, which includes the leadscrew I42, and which is indicated as being at ground potential. It will be seen that by utilizing the guide rods as feed conductors and the leadscrew as a common return conductor, the circuits to and from the recording and'reproducing heads may be maintained without the use of long fiexible'jumper wires which would always be in the way, detract from the appearance oi the apparatus and, due to frequent flexing, be likely to crystallize and break. It will also be noted that, upon lifting either the recording head handle I89 or the reproducing head handle I3I, the movement of the respective heads axially of the platen 38 is not only stopped but also the electric circuits to the respective nuts I49 and I52 disengage the leadscrew I42.

As an additional feature of construction a panel 223 of insulating material is secured to one of the angle bars I 4 and extends. longitudinally of the drum 38. This panel affords partial protection to the record film against being accidently struck and damaged by articles resting upon the surface upon which the base plate I2 may be supported, but principally provides a mounting for controls such as volume controls, for the input of the recording amplifier and the output of the reproducing amplifier, monitoring jacks, switches and the like. The uppe edge of the panel may conveniently be marked off as a scale so that various portions of the sound record may be measured and conveniently located. I

Having thus described the invention in detail, what is claimed as new and desired to be secured by Letters Patent is:

1. In a sound recording apparatus having a rotatable record drum, power means within and for rotating said record drum, a fixed guide bar extending along and in spaced relatibn 'to said record drum, a rotatable feed screw paralleling said guide bar and electrically insulated therefrom, means connecting said feed screw to be driven by said record drum rotating means, an electrical translating device mounted on said guidebar and connected to be moved along said guide bar by said feed screw, said electric translation device having insulated current terminals connected respectively with said guide bar and said feed screw, and utilization circuits connected, respectively, with said guide bar and said feed screw.

' rotatable record drum, power means within and for rotating said record drum, a fixed guide bar extending along and in spaced relation to said record drum, said guide bar having a surface groove extending longitudinally thereof, a rotat able feed screw paralleling said guide bar and electrically insulated therefrom, means connecting said feed screw to be rotated by said record drum rotating means, a carrier mounted on said guide bar l'or rotary and longitudinal movements with respect thereto, said carrier having thereon a. segmental threaded nut which may be brought into engagement with said feed screw upon rota tional movement or thecarrierso as to connect the carrier to be driven along the guide bar by and upon rotation of the feed screw, an electric translation device mounted on said carrier and adapted to be operatively positioned with respect to said record drum when the segmental nut of the carrier is engaged with the feed screw, said translation device having a pair of terminals which are relatively electrically insulated, means connecting said terminals, respectively, with said guide bar and said feed screw, utilization circuits connected, respectively, with saidguide bar and said feed screw, and a spring-pressed latch element engageable, when saidcarrier isrotatably moved on said guide bar so as to elevatesaid electric translation device fromits operative position with respect to the record drum, in the groove of said guide bar so as to releasably maintain said translation device in its elevated position.

3. In a sound recording apparatus having a rotatable record drum, power means Within and for rotating said record drum, afixed guide bar 7 extending along and in spaced relation to said heads is interrupted as soon as the fractional 2. In a sound recording apparatus having a record drum, said guide bar having a surface groove extending longitudinally thereof, a rotatable feed screw paralleling said guide bar and electrically insulated therefrom, mean connecting said feed screw to be rotated by said record drum rotating means, a carrier mounted on said guide bar for rotary and longitudinal movements with respect thereto, said carrier having thereon a segmental threaded nut which may be brought into engagement with said feed screw upon rotational movement of the carrier so as to connect the carrier to be driven along the guide bar .by and upon rotation of the feed screw, an electric translation device mounted on said carrier for pivotal movementrelative to the carrier in both horizontal and vertical planes and adapted to be operatively positioned with respect to said record drum when the segmental nut of the carrier is engaged with the feed screw, said translation device having a pair of terminals which are relatively electrically insulated, means conmeeting said terminals, respectively, with said guide bar and said feed screw, utilization circuits connected, respectively, with said guide bar and said feed screw, and a spring-pressed latch element engagea'ole, when said carrier is rotatably moved on said guide bar so as to elevate said electric translation device from its operative position with respect to the record drum, in the groove of said guide bar so as to releasably maintain said translation device in its elevated position.

4. In a sound recording apparatu having a rotatable record drum, power means within and for rotating said record drum, a fixed guide bar extending along and in spaced relation to said record drum, a rotatable feed screw paralleling said guide bar, a carrier, slidably mounted on said guide bar and engaged with said feed screw so as to be relatively fixed with respect to the record drum and to be moved by the feed screw, as the latter is rotated, along the guide bar, a weighted arm pivotally mounted for movement in a vertical plane on said carrier, means for adiustably raising and lowering said weighted arm relative to said carrier, an electrical translation device pivotally mounted for movement in a vertical plane on said weighted arm andpositioned in operative relationship with respect to said record drum, and means for raising and lowering said electrical translation device lative to said weighted arm so as tovary the operative relationship between said translation device and said record drum.

,5, In a sound recording apparatus having a rotatable record drum, power means within and ror'rotating said record drum, a fixed guide bar extending along and in spaced relation to said record drum, said guide her having an integral latch element extending longitudinally thereof,

a rotatable feed screw paralleling said guide bar and electrically insulated therefrom, means con- I necting said feed screw to be rotated by said record drum rotating means, a carrier mounted on said guide bar for rotary and longitudinal rier clutching means is tractionally engaged with said feed screw, said translation device having a pair of terminals which are relatively electrically insulated, means connecting said terminals, respectively with said guide bar and said feed screw, utilization circuits connected, respectively, with saidg-uide bar and said feed screw, and a pressure-actuated latch member engageable, when said carrier is rotatably moved on said guide bar so as to elevate said electric translation device from its operative position with respect to the record drum, with said latch element of the guide bar so as to releasably maintain said translation device in its elevated position although permitting freemovement of said translation device along said guide bar longitudinally of said record drum.

CHARLES D. SHRADER.

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