US2335586A - Sound recorder and reproducer - Google Patents

Description

Nov. 30,1943. A. w.- DE SART, SR 2,335,586

SOUND RECORDER AND REPRQDUCER I Filed Sept. 27, 1940 A Sheets-Sheet 1 .90 III/ F Tictl i Q v "'4 INVEN TOR.

v ATTORNEY Nov. 30, 1943. w, s -r, 5 2,335,586

SOUND RECORDER AND REPRODUCER Filed Sept. 27, 1940 4 Sheets-Sheet 3 ATI'OKN av Nov. 30, 1943. A. w. DE SART, 92

SOUND RECORDER AND REPRODUCER 4 SheetsSheet 4 Filed Sept. 27, 1940 l lfl lifll myENTo iii/7 fifflzir/ in W A W TTOKND/ Patented Nov. 30, 1943 sourin BECORDERLAND anrnonucm Albert w. De Sart, Sr., Los Angeles Cali1., as-

signor to United Acoustigraph Corporation, Los Angeles, Call!" a corporation of Nevada Application September 27, 1940, Serial No. 358,623

' 1-: Claims.

This invention relates to a sound recorder and reproducer, such as may be used for example for dictation.

Such machines usually include a stylus head,

cooperating with a relatively movable member capable of carrying a record. This member may be in the form of a disc, cylinder or flexible loop, driven at a convenient speed; and the stylus carried by the head is caused appropriately to traverse the record.

For recording purposes, a microphone is caused to aflect the head, the stylus being vibrated to impress a record on the record carrying member. For reproducing, the vibrations are imparted to v the stylus by the record, and the motion of the stylus is caused to affect an electric circuit which in turn operates. a sound reproducer, such as a loud speaker or a telephone.

It is one of the objects of this invention to provide a simple and reliable instrumentality of this character.

It is still another object of this invention to make it possible in a simple manner to obtain duplicate records, or to facilitate the duplication of prior recorded records. This is accomplished by providing a plurality of heads, so arranged that one operating as a reproducer may be optionally utilized to feed recording impulses to the other, operating as a recorder, or both may be caused to operate as recorders and subjected simultaneously to the impulses transmitted from a microphone.

It is clear then that at least one of the heads be capable of performing a dual purpose-either for recording or for reproduction. Accordingly it is another object of this invention toprovide a simple mechanism for making it possible to condition the dual purpose head for either of its functions.

In apparatus of this character when used as a business machine for the dictation of letters. reports, etc., it is highly desirable to be able to play back at least the last portion of the recorded matter atv anytime. A back spacer is used ordinarily for this purpose. It is another object of this invention toprovide a simple and effective back spacer, and especially one that can be readily adiusted to provide any desired amount of back spacing within llimits.

This invention possesses manyother 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 drawings accompanying and forming part of the present specification. 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 by the appended claims.

' In the drawings:

Figure 1 is a front elevation ofthe dictating machine; v

Fig. 2 is a side elevation thereof, part of the casing being broken away to show the drive mechanism;

Fig. 3 is a top plan view thereof, part of the casing being broken away to show the drive mechanism;

Fig. 4 is a fragmentary detail section, as seen on plane 4-4 of Fig. 1;

Fig. 5 is a section as seen on plane 55 of Fig.4;

Figs. 6 and 7 are fragmentary detail sections asseen on correspondingly numbered planes of Fig. 2;

Figs. 8, 9 and 10 are fragmentary sections as seen on correspondingly numbered planes of Fig. 'I;

Fig. 11 is an elevation of a portion of the back spacer mechanism on an enlarged scale;

Fig. 12 is a section as seen on plane l2--|2 of Fig. 11;

Fig. 13 is a fragmentary section as seen on plane Iii-l3 of Fig. '7; 1 r

Fig. '14 is an elevation of the right hand end of the stylus head of Fig. 7;

Fig. 15 is a view similar to Fig. 7, showing an alternative position of the stylus head; and

Fig. 16 is a wiring diagram, showing the circuits by which the stylus heads are connected to the amplifier.

In the present instance, the record carrying member may be in theform of a flexible loop. As shown most clearly in Fig. 1, two such flexible loops A and B are indicated, whereby duplicate records when desired may be obtained; or else, as

stylus which is intended to cooperatewith loop B is shown as incorporated in the stylus head 9. As shown most clearly in Fig. 1, the two loops A and B, together with their associated mechanism are arranged generally on each side of a vertical center line of the apparatus.

The manner in which the loops maybe supported and driven will now be described. Since the mechanisms for driving the loops are sub stantially identical, it is necessary to describe but one of them in detail.

Thus the loop A is shown as passing over the vertically spaced roller structures 3 and I40 (Figs. 1, 2, 3, 4, 6, 7 and This flexible loop may be made from thin material capable of regroove of the record carrying member A. Dur-' ing reproduction, the stylus head 8 is permitted to have a universal motion, including lateral compliance, so that the stylus 35 may be vibrated by the undulations formed in the grooves of the member A.

The upper roller 3 is shown as tubular in form. it is fastened to a shaft I34. This shaft is journaled at its left hand extremity as shown in Fig. 2 by the aid of a bracket I36. This bracket is fastened to the left hand surface of a wall I31 projecting vertically from a base I30. The shaft extends through the wall I3I and is coupled as by a flexible coupling $38, with the speed reduction mechanism 6 illustrated most clearly in Fig. 2. This speed reduction mechanism is driven by a motor 5 mounted upon a shelf I32. shelf is appropriately attached to the right hand side of the wall I3I.

The lower roller structure I40 is shown to best advantage in Figs. 4 and 5. This roller is shown as formed of the hollow tubular member I43 telescoped over the flanges of the end members I44 and I45. These end members are provided with hubs freely rotatable on a hollow shaft I46. Both the members I44 and I45 have projecting limiting flanges I60 confining the loop A against excessive axial movement. The upper roller 3 may also he provided with an inner flange for contacting the loop A. The lower roller shaft I46 is so adjusted that the loop A tends to run toward this inner flange on the upper roller. In this way it is assured that the loop will not run off the rollers.

The hollow shaft I46 is so arranged that it may be lifted vertically to permit removal and replacement of the loop A. The weight of the roller keeps the loop in proper tension when the This . ture I54.

roller structure I40 is permitted to move downv wardly.

The support for shaft I46 includes an arm I41 whichispivotally mounted by the aid of a pin,

I48. This pin I48 is secured to the upright wall I3I. The hollow shaft I46 is securely fastened into the arm I41 near the free end of this arm. Accordingly, in response to the force of gravity exerted by the roller structure I40, the arm I41 may rock in a clockwise direction so as to keep the loop A stretched.

When it is desired to replace or remove the loop A provisions are made to lift arm I41 from the position illustrated in Figs. 4 and 5 and to hold it in elevated position. For this purpose a tooth I5I may be secured upon the wall I3I.

This tooth is adapted to cooperate with a hook I50 carried by the arm I41. Hook I50 is provided through the hollow shaft I46. This plunger I53 has an inner flattened end pivoted to the extension I52 of the hook I50. Its outer end carries a button structure I54 exposed at the left hand end of the roller structure I40.

Normally a compression spring I55 serves to urge the hook I50 in a clockwise direction. The right hand end of this spring abuts a collar I62 fastened within the hollow shaft I46, and through this collar the rod I53 passes. hand end of spring I55 abuts against a shoulder formed on the rod I53 beneath the button struc- When the roller structure I40 is lifted as by the aid of the thumb piece I49 attached to the hollow shaft I46, the hook I50v is caused to engage the tooth I5I and the removal and replacement of the loop may then be readily accomplished. In order to replace the idler roller I40 into proper operative relation, the button I54 is pushed inwardly, rocking the hook I50 in a counterclockwise direction against the pressure of the spring I55. This frees the hook I50 from the tooth I5I and the roller structure is permitted to drop by gravity to the position indicated.

The manner of driving and supporting the loop Q B is similar to that Just described for loop A. This loop B passes over the upper driven roller 4 and over a lower idler roller structure MI. The upper roller 4 is mounted on a shaft I35. This shaft I35 as shown most clearly in Fig. 3 is driven through a flexible coupling I39 and reduction gearing i from the motor 5. The lower idler roller structure I 4| may be similarly lifted and retained in the lifted position by mechanism identical with that illustrated in Figs. 4 and 5. Both loops A and B are shown in the present instance as driven in the same direction.

The stylus head 9 cooperating with the loop B is arranged in this instance to serve solely as a recording head; that is, it has no provisions for lateral compliance. For this purpose the stylus head 5 is rigidly mounted on an arm 31. This arm 31 in turn is provided with pivot ears 30 and 39, by the aid of which the arm 31 is pivoted about a stationary supporting and guiding rod 40. As shown most clearly in Figs. 1 and 2, the left hand end of the rod 40 is supported in a bracket 22 supported on the left hand side of the wall I 3 I. This bracket has a horizontal portion serving as a lower plate extending beneath the rod 40.

In order to place the recording head 9 into cooperative relation with the loop B, the arm 31 is rotated in a counterclockwise direction as illustrated in Fig. 6 until the stylus 35 rests upon allel with the axes of the rollers 3 and 4. The

horizontal arm I64 of the crank lever carries a weight 41 to keep the nut 46 in operative engagement with the lead screw I0. Furthermore, the weight of the recording head 9, the arm 31 and its associated parts is such as to produce adequate pressure for the recording stylus 35.

The left The lead screw |8 may be journaled at its left hand end as seen in Fig. 2 in the bracket 22. Its right hand end is journaled in the wall |3| and it passes through this wall. The right hand end carries a driven pulley I88 adapted to be rotated as by a flexible belt II from a small driving pulley I81 mounted on one of the roller driving shafts such as shaft I34. The transmission ratio for the rotation of shaft I8 is chosen so that an appropriate fine pitch is obtained for the record groove formed on the record carrying member B.

In order to facilitate placing the record head 8 in and out of operative position with respect to the loop B, use is made of a finger lift 8| placed transversely of the arm 31. To render the recording head 8 inoperative the finger lift 8| is pulled upwardly until the arm 31 comes to rest in a position slightly beyond the vertical. Due to the engagement of the strap I83 with the horizontal arm I84 of the nut carrying lever, the nut 48 is simultaneously disengaged from the lead screw l8. With the nut disengaged, the head 8 may be moved along guide rod 48 to any desired I point.

Manual manipulation is thus rendered possible to place the stylus head 8 into cooperative relation with any desired portion of the record carrying member B.

The stylus head 8 is so arrangedvthat it may be used optionally for recording or reproduction.

This stylus head 8 as shown most clearly in Figs. 6, 'l and 15, is firmly mounted in bracket 12. This bracket 12 carries a shaft 13 about the axis of which the bracket 12 may swing. This axis is transverse to the axis of the roller 3. In this way during the process of reproduction the stylus 38 is free to move in a direction generally parallel to the axis of the roller 3; in other words. the stylus has lateral compliance. The shaft 13 is held in place with relation to the bracket 12 as by the aid of the set screw 14.

' The shaft 13 is accommodated for oscillatory motion in a block 18. Axial motion of shaft 13 in .block 18 is restrained by set screw 18 (Fig. 7) threaded in block 15 and having an inner rounded end adapted to engage in groove 11 formed in the shaft 13. r

The block I8 is in turn mounted for pivotal oscillation about an axis parallel to the axis of the roller 3. As shown most clearly in Fig. 9, opposite edges of the block I8 have tapered recesses for the accommodation of pivot screws 18 and"|8 accommodated in the sides of an'arm 38. This arm 38 is similar in structure to the arm 31 and may be pivotally mounted upon a guide rod 48 paralleling the guide rod 48 associated with the arm 31. For recording purposes the block 15 is restrained from rocking about the axis of the pivot screws I8, 18. This may be accomplished for example by holding the flattened end 88 of the shaft 13 against the lower end of an adjustable set screw 8|. This position is indicated in Fig. 7. This flattened end 88 in this instance is urged and held against the abutment formed by the lower end of the said screw 8| by the aid of an eccentric cam 82 (Figs. 7 and 8). This cam is fastened to a cam shaft 84 appropriately journaled in block 38. The shaft 84 may be manipulated to the clamped position of Fig. 7 by the aid of a handle 85 fastened to a collar |88 attached to the left hand end of the shaft 84.

Not only does the cam 82 restrain pivotal movement of the bracket 12 and block 15 about the axis of the screws 18 and 18, but oscillatory movement of the bracket 12 about the shaft 18 I8. Accordingly bracket 12 inv this position virtually forms a rigid connection with the arm 38. The entire weight of the arm 38, bracket 12, stylus head 8 and their associated parts is then record carrying 'loop'A. In order to provide a drive connection fro head 8 to the lead screw l8, brackets 42, .43 are fastened to the rear end of the arm 38. In these brackets is iournaled the crank arm 44 having a vertical extension 48. This vertical extension carries the mutilated nut 48. The horizontal arm of the crank 44 carries the weight 41 to ensure proper operative engagement-between the nut 48 and the lead screw l8. Simi-' larly a strap 48 (Figs 7 and 9) extends across the bottom of the arm 38 and below the horizontal arm of the crank 44. Thus when the head 8 is raised in a counterclockwise direction and out of operative relation with the record carrying member A the strap 48 serves to rotate the crank arm 44 so as to bring the nut 48 out of engagement with the lead screw l8. A handle 5| is fastened to the plate 88 carried by the block I8 for ready manipulation of the head 8 in this manner.

The plate 88 as shown most clearly in Figs. 3, l3 and 14 has projections 8| and 82 overlying the top of the bracket 12. Compression springs 81 and 88 may be disposed between these extensions 8| and 82 and the bracket I2 to serve as resilient centralizing means for the bracket 12 when the bracket I2 is free to oscillate about the axis of the shaft I3. Furthermore, the arms 8| and 82 may carry stop set screws 85 and 88 as shown in Fig. 13 to provide definite limits to the oscillation of the head 8 about the axis of shaft 13. The springs 81 and 88 may serve con- .veniently as lead-in connectors to the coil associated with the stylus head 8.

' When it is desired to place the head 8 in condition for reproducing, the cam 82 is rotated in a counterclockwise direction to the position illustrated in Fig. 15. In this position the fiattened end 88 is freed from the bottom of the set screw 8|. Accordingly the bracket 12 and the head 8 fastened thereto are free to rock about the axis of pivots l8, 18, in a vertical direction; and at thesame time the shaft 13 is free to rock within the block 15. In this position the weight of the arm 38 is insufilcient to urge its forward end against the top edge of the bracket 81. In this way only the weight of the bracket I2 and the head 8 is used to urge the stylus 35 downwardly against the record carrying loop A. Thus there is a reduction in the force of gravity 'acting to press the stylus against the record.

This is essential. for reproduction purposes and -in order to permit ready lateral compliance of head. Release of the lever I will cause the head I 8 and the nut 46 to assume the operative position of Fig. 7.

For this purpose use is made of a shift bar mechanism I8. This includes a bar 24 of general rectangular configuration and shown to best advantage in Figs. 7, 10 and 12. The longitudinal axis of this lift bar is parallel with the traversing motion of the head 8. spacing operation involves an upward movement of the bar 24. Its upper surface then contacts with the lower surface of the strap I10 fastened across the bottom of the supporting arm 36. This bar 24 is also free to move longitudinally. This longitudinal movement causes the arm 36 to be moved along with the bar 24. This longitudinal movementis allowed to occur since lifting of the arm 36 disengages the stylus 35 from the record blank A andthe nut 46 is likewise freed from the lead screw I6.

For the present it may be noted that this bar 24 is mounted for the required longitudinal movement in a hollow guide 23. The left hand end of guide 23, as seen in Fig. 10, is provided with a cover "I. A similar cover I12 is shown for the right hand end of theguide 23. In this way a restraint is placed upon both ends of the bar 24 against relative movement of the bar 24 and the guide 23 in a direction transverse to the longitudinal axis of bar 24.

The guide 23 is mounted at its opposite ends in the arms I3 and 20. These arms are mounted for free pivotal motion about the shaft 2| and the thumb piece I1 is formed on an extension of the ar I9. Accordingly a depression of the member I1 as heretofore stated will cause a vertical lift of the bar 24 with the attendant freeing of the head 8 and nut 46 from their respective cooperating members. This nut 46 is disengaged by the aid of a bar 52, supported in parallel spaced relation to guide 23 as by the aid of appropriate posts I80. The top edge of this bar 52 is arranged to contact the end'of the arm 48 of the nut carrying lever 44. This engagement and consequent lifting of'the nut 46 occur almost as soon as the guide 23 moves upwardly.

The upward lift as just described, also ensures motion of the bar 24 toward the left as viewed in Fig. 10; that is in a back spacing direction. For this purpose bar 24 carries at its right hand end a hardened cam plate 25. This cam plate 25 has a cam or sloping surface 26 adapted to cooperate with the inner end of a screw 30. This screw is shown as adjustably mounted in a bracket 3I on the right hand side of the bracket 22 as viewed in Fig. 1. The bar 24 is constantly urged toward the right by a compression spring 28 interposed between the left hand end of the guide 23 and the left hand end of the bar 24.. A stop I85 on guide 23 engages a notch I86 at the end of bar 24 to limit this movement. Screw 30 is adjusted to provide a small clearance between the end of screw 38 and surface 26when bar 24 is in its lowest position. Accordingly, the bar 24 lifts a short distance in response to the operation of member I1, before the cam plate 25 engages the inner end of the screw 30. Further lifting of bar 24 causes the sloping surface 26 of cam plate 25 to slide along the inner end of screw 30, which urges bar 24 to the left. This longitudinal movement of the bar 24 is effective to move the arm 36 in a backspacing direction.

The extent of this back spacing movement may be adjusted by the aid of the adjustable stop 61 (Fig. 6) cooperating with the member I1.

The back This stop is in the form of a headed screw 68 threaded into a tapped aperture 63 formed on the bracket 22. A 100K nut 16 maintains the stop 61 at any adjusted height. The larger the throw of arm I9 permitted by the stop 61, the farther will the bar 24 be moved toward the left as viewed in Fig.10. The adjustment can be made such as to provide for a back spacing to bring the head 8 into the next adjacent groove, or any other groove within the limits of the back spacer. I a I It must be ensured that the bar 24 will be maintained in its retracted or back-spaced position until the head 8 is replaced in full operative position with respect to the record carrying memher A, for otherwise the head would be returned to the original position. For this purpose means are provided for temporarily restraining the bar 24 in its back spaced position. This means in pludes a lever 58 having a hook 6|! at its right hand end, and carried by the guide 23. This hook 60 is intended to engage a notch 6I in thebottom of the bar 24. The lower wall of the guide 23 is apertured as indicated at 62 to permit the hook 60 to enter the notch 6I. As soon as the back spacing movement takes place, the hook 66 is brought into play with respect to the notch 6| so as to maintain the bar 24 in its back spaced position. For this purpose lever 58 as shown most clearly in Figs. 10, 11 and 12, is mounted on a plate or bracket 55 carried by the guide 23. This plate 55 is provided with a pivot pin I13 upon which the lever 58 is pivoted. A torsion spring 59 is wound'around the pin I13. One free end engages the'lower wall of the guide 23. The other end engages the left hand arm of the lever 58 urging the lever constantly in a counterclockwise direction or toward engaging position.

It is essential that the tooth 60 be caused to engage in the notch 6I only at the completion of the movement of the lever I1. And this action is to take place irrespective of the adjustment of the back spacing operation. For this purpose the plate 55 is adjustably mounted upon the wall of the guide 23. In this way for any adjustment of the adjustable abutment 61 cooperating with the member I1, there is a corresponding adjustment of the plate 55. This adjustment is permitted by the aid of the slots 51 in the plate 55 through which pass thefastening screws 56.

With the bar 24 in the depressed position of Fig. 10, the tooth 60 is urged out of cooperative relation with the notch 6I'. This is accomplished by the aid of the adjustable abutment 63 cooperating with the arm 65 of lever 58. This adjustable abutment is in the form of a screw threaded into the bracket 22 and having a head 64 adapted to engage the arm 65. The weight of the bar 24 and its associated parts overcomes the force of the spring 59 and the hook 60 is caused to disengage from the notch 6I when the bar 24 moves to the disengaging position of Fig. 10. Accordingly the compression spring 28 is again effective to urge the bar 24 toward the right until notch I86 on the bar engages the stop I on guide 23.

The cycle of operation for the backspacer in response to a depression of the member I1 may now be set forth. First of all, th bar 24 lifts, the initial movement causing it to engage arm 36 and lift arm 36 serving to disengage stylus 35 of head 8 from the record, and free the corresponding nut. 46 from lead screw I0. Further lifting causes bar 24 to be given a motion toward the left as viewed in Fig. 10. This motion toward the left carries the stylus head in a back spacing direction. The bar 24 is retained in that position by book 00 engaging in the notch 0|. When the member I! is released, the arm comes in contact with the stop 63, but only after the head 0 is again In cooperative relation with the record carrying member A. The bar 24 is released by hook 00 and the elements are returned to the position of Fig. 10. I

The connections for th system are illustrated diagrammatically in Fig. 16. This figure shows a. transducer I4,'also indicated in Fig. 1. This transducer I4 is intended to operate either as a sound reproducer or as a microphone. It may be An amplifier system I02 may be installed on the apparatus below the bracket 22 and back of a front panel I00. It is shown as having input and output circuits, and as provided with power leads I03. These leads I03 are intended to be connected to any appropriate commercial source of electric power supply. The arrangement is furthermore such that by appropriate operation of a switch mechanism I00 the system may be optionally utilized for recording or for reproduction. The switch mechanism I00 is provided with an operating handle IOI (shown also in Figs. 1 and 2).

Switch mechanism I00 is provided with a pair of contact making arms I06 and I09. In the full line position of Fig. 16, the transducer I4 is arranged in the input circuit of the amplifier and the heads 8 and 9 are both in the output circuit of the amplifier whereby these heads may be used for recording. The input circuit of the amplifier thus includes lead I01, arm I06, contact point 0, lead II4, transducer I4, and ground connections H2 and I08. The output circuit of the amplifier includes the connection I I0, arm I09, where the circuit branches. One branch proceeds by way of contact member I25, connections I20 and I20 to the head 8, ground connection I I0, back to groundconnections III of the amplifier system I02. The other circuit proceeds by way of contact I22, connection I23, through a switch I24 to the head 9, ground connection I2I, back to ground connection III. In this position therefore both heads are active as recorder heads, and are in parallel in the amplifier output circuit.

Should it be desired to make but one record instead of two. the switch I24 is operated to the dotted line position of Fig. 16. This switch, as shown most clearly in Fig. 1, may be mounted upon-the front wall 'I3I near the upper edge thereof. In the dotted line position the head 0 is replaced by a load resistance I20 whereby the circuit'constants are maintained whether the head 9 is active or inactive.

If it be desired to reproduce a record, the switch mechanism I00 is operated to assume the dotted line position of Fig. 16. In this position the amplifier input circuit is connected to the head 0 as follows: connection I01, arm I00, contact point II9, connection I20, head 8, and ground connections H8 and I08. The head 9 is in this condition out of the circuit as it is designed only for recording purposes. The output circuit of the amin Fig. 16 may also be mounted adjacent switch I24 as illustrated in Fig. 1. This switch I I1 is operated when it is desired to make a record. by the aid or head 0, from a previously made record. With the switch III thrown to the dotted line position of Fig. 16, the transducer I4 is left out of the circuit, and head 0 is substituted therefor in the output circuit of the amplifier. The input circuit to the amplifier is left the same as before. The output circuit now includes the connection IIO, arm I09, contact IIO, connection H0, switch I I1, connection I20, switch I24, head 9 and ground connections HI. and III. Thus electrical impulses generated in head 0 by a record on member A affect the input side of the amplifier I02. The output side passes amplified impulses to the recorder head 9. V

A volume indicator I05 is shown as provided. on the amplifier system. The volume control button I04 for the amplifier may also be conveniently mounted on the front wall of the amplifier panel I. g The switch I02, shown mounted near the upper edge of wall III (of Fig. 1) may be used to control the supply of energy to the motor 5 and the amplifier system I02. A warning light I03 may be used to indicate when the motor and amplifier circuits are energized. Similarly, a light I04 serves to indicate failure of the power supply.

To provide for adjusting the force exerted by stylus 35 on cooperating record loop A when the head is in recording condition, an adjustable weight I00 (Fig. 3) oi. the order of a few ounces is provided. This weight I08 is slidable on an arm I09 attached to pivot car, on carriage 00 in any convenient manner, as by screws I00 (see Figs. 2, 3, 7 and 8), and extending transversely of guide bar 40. A set screw I9I serves to secure weight l00 in adjusted position on arm I80. 0bviously, by altering the position of weight I00 on bar I09 with respect to guide bar 40, the weight effective on the stylus can be varied.

Since the weight I00 is supported on the carriage 00, when the latter rests on the guide member 01 for play back or reproduction, weight I00 will be without efiect'on stylus'35, regardless of the position of the weight on arm I00.

What is claimed is:

I. In a combination sound recorder and reproducer head structure adapted to be placed into mechanical contact with a record carrying membeer with optional relatively light or heavy gravity pressure, a pivoted arm serving as the main support for the structure, a supplemental support pivotally mounted on the arm on an axis parallel I limiting means is inactive.

2. In a combination sound recorder and reproducer head structure adapted to be placed into mechanical contact with a record carrying member with optional relatively lightor heavy gravity pressure, a pivoted arm serving as the main support for the structure, a supplemental support pivotally mounted on the arm on an axis parallel to the arm pivot but spaced closer to the point where said mechanical contact is to be made, a combination head carried .by said supplemental support, means for optionally restraining said supplemental support from pivotal movement with respect to the arm, means limiting the extent of angular movement of the arm in a direction required to contact said record, said head being so arranged that when the pivotal movement of said supplemental support is restrained, contact with the record is established while said limiting means is inactive, and means forming a pivotal mounting for the head on said supple- ,mounting means to prevent movement of the head about the axis of said mounting means when said restraining means is active.

3. In a combination sound recorder and reproducer head structure adapted to be placed into mechanical contact with a record carrying member with optional relatively light or heavy gravity pressure, a pivoted arm serving as the main support for the structure, a supplemental support pivotally mounted on the arm on an axis parallel to the arm pivot but spaced closer to the point where said mechanical contact is to be made, a combination head carried by said supplemental support, means for optionally restraining said supplemental support from pivotal movement with respect to the arm, means limiting the extent of angular movement-of the arm in a direction required to contact said record, said head being so arranged that when the pivotal movement of aid supplemental support is restrained, contact with the record is established while said limiting means is inactive, and a shaft attached ,to the head and having an axis transverse to that of the supplemental support, one end of said shaft cooperating with the restraining means to maintain the'supplemental support against angular motion, said shaft and restraining means also cooperating to restrain angular motion of the shaft.

4. In a back spacer mechanism for a sound head, a lift bar normally out of engagement with said head, means for moving said barinto engagement with the head, means responsive to said movement for urging the bar in a back-spacing direction, and means for temporarily restraining the bar from back spacing motion until the bar is moved out of engagement with the head.

5. In a back spacer mechanism for a sound head, a lift bar normally out of engagement with said head, means for moving said bar into engagement with the head, means responsive to said movement for urging the bar in a backspacing direction, means for temporarily restraining the bar from back spacing motion until the bar is moved out of engagement with the head, and means for adjusting the extent of said back spacing movement.

6. In a device of the character described, a stylus head having a stylus, a carriage for the head, a guide bar for the carriage, said carriage being adapted to swing about said barso that said stylus may rest on a record carrying member, means to cause the stylus to traverse the record, a support for said bar, a backspace bar guided for movement substantially parallel with the guide bar, means to move said bar to engage said carriage and swing it about the guide bar to free the record from the stylus, and means to move the back space bar in a direction parallel with the guide bar as it is raised.

7. In a device of the character described, a stylus head having a stylus, a carriagefor the head, a guide bar for the carriage, said carriage being axially movable along said bar as well as swingable about the axis of the bar, said stylus being adapted to engage the surface of a record carrying member to limit the swing of the carriage in one direction, a feed screw to advance the stylus transversely of the record surface, a feed nut carried by the carriage and engaging the feed screw, a back space bar adapted to be raised so as to engage the carriage and lift the stylus from the record surface, and includingv means whereby said movement also disengages the feed nut from the feed screw, and means whereby the back space bar is moved parallel with the guide bar as it is raised, whereby the stylus head and carriage are moved.

8. In a device of the character described, a

the stylus from the record surface, as well as to move the carriage axially of the guide bar.

9. In a device of the character described, a stylus head having a stylus, a carriage for the head, a guide bar for the carriage, said carriage being axially movable along said bar as well as swingable about the axis of the bar, said stylus being adapted to engage the surface of a record carrying member so that the head and carriage are supported thereby, a back space bar below the carriage, means to raise the back space bar so as to lift the stylus from the record surface, means to move the back space bar parallel with the guide baras it is raised, means including a detent adapted to engage said bar when it is raised to prevent return movement, and means to disengage the hook from said bar to permit return movement when the bar is lowered to its initial position.

10. A back spacer for a stylus head carriage, comprising a pivotally mounted frame having-a channel member, means to swing said frame about its pivot so as to lift said "member, a bar slidable in said member and having a surface adapted to engage said carriage, means forming a stop, said bar having an inclined surface engaging said stop, and means resiliently urging said surface against the stop, said surface bein so inclined that transverse movement of said bar with respect to said stop will cause the bar to move longitudinally in the channel member.

spect to said stop will cause the bar to move longitudinally in the channel member, a detent mounted on the channel member, means on said bar adapted to be engaged by said detent, and means to maintain said detent out of engagement with said means when the channel member is in its initial position, said maintaining means being adapted to be engaged by the detent upon longitudinal movement of the bar in response to raising said member, whereby said bar is preventedfrom returning to said stop until the member is lowered to its initial position.

12. In a device of the character described, a carriage, a guide bar, said carriage being movable longitudinally of said bar as well as angularly about the axis of the bar, astylus head pivotally supported by the carriage, the axis of the pivots being parallel with the axis of the bar. and means to lock the head against move- "ments about said pivots.

13. In a device of the character described, a carriage, a guide bar, said carriage being movable longitudinally of said bar as well as angularly about the axis of the bar, a guide member to support the carriage and limit its angular movement about the bar, a stylus head pivotally mounted on the carriage, and having a stylus adapted to support the head on the surface of a record carrying member, and means to swing the head about said pivots, whereby the carriage is lifted from the guide member and supported by the stylus. I

14. In a device of the character described, a carriage, a guide bar, said carriage being movable along the bar as well as swingable about the bar, a guide member to support the carriage, a block member pivotally mounted on the car- ,riage, and a stylus head pivotallyv mounted on the block, the axes of said pivotal mountings being perpendicular to each other.

- the carriage is lifted from 15. In a device of the character described, a

stylus head adapted to cooperate with a record carrying member, means to support the stylus head for movement parallel with the record surface as well as toward and away from said surface, a tiltable frame having a part adapted to engage said head and disengage it from said record upon tilting the frame, said part being supported in the frame for movement in a direction parallel with the record surface, and means to move said part as the frame is tilted.

16. In a device of the character described, a frame, a channel member movably supported by said frame, a bar slidableflin said member and having an inclined end surface, a stop on said frame, means urging the bar so that said end surface engages said stop, a detent carried by said member adapted to engage the bar and prevent its movement in response to said means, and means to disengage the detent from the bar in response to movement of said member in one direction. a

1'1. In a device of the character described, a carriage, a guide bar, said carriage being movable longitudinally of said bar, as well as angularly about the axis of the bar, a guide member adapted to support the carriage and limit its angular movement about the bar, a sound head pivotally mounted on the carriage, and having a stylus adapted to support the head on the surface of a record carrying member, means to swing the head about said pivots, where-by the guide member and supported by the stylus, an arm on the carriage extending transversely of the guide bar, and a weight supported on said bar and adjustable therealong, said weight acting on the stylus only when the sound head ALBERT w. DE SART, Se.

is in recording condition.

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