US2275961A - Multiple lane magnetic sound recording system - Google Patents

Description

MULTIPLE LANE MAGNETIC SOUND RECORDING SYSTEM Filed Jan. 22, 1938 5 Sheets-Sheet 1 N in van zbr:

Herman Heller:

March 10, 1942. H. s. HELLER MULTIPLE LANE MAGNETIC SOUND RECORDING SYSTEM Filed Jan. 22, 1938 5 Sheets-Sheet 2 lm/en tor. Herma ,S'Jleller:

March 10, 1942. H. s. HELLER MULTIPLE LANE MAGNETIC SOUND RECORDING SYSTEM 5 Sheets- Sheet 3 Filed Jan. 22, 1938 lnvenfor. Herman 61 fiellen Mar -ch 10, 1942. H. s. HELLER MULTIPLE LANE MAGNETIC SOUND RECORDING SYSTEM 1938 5 Sheets-Sheet 4 Filed Jan. 22,

NUbQQQQGE March 10, 1942. H. s. HELLER MULTIPLE LANE MAGNETIC SOUND RECORDING SYSTEM Filed Jan. 22, 1938 5 Sheets-Sheet 5 Patented Mar. 10, 1942 MULTIPLE LANE MAGNETIC SOUND RECORDING SYSTEM Herman S. Heller, West Los Angeles, Calif.

Application January 22, 1938, Serial No. 186,351

Claims.

This invention relates generally to methods of and apparatus for magnetically recording sound.

A shortcoming of magnetic sound recording methods and apparatus as known heretofore has been that, in order to secure recordation of all of the desired frequencies, the magnetic recordingv wire or tape has to be driven at such a high speed that it was not possible to make a continuous recording of a desirable duration on a convenient length of the recording wire or tape.

It is accordingly a primary general object of the present invention to provide a magnetic recording machine and method in accordance with which a recording of comparatively long duration may be made on a recording element of a normal or convenient length.

Reference is here directed to a copending application filed by Herman S. Heller and Leo G. Butler, entitled Method of and apparatus for magnetically recording sound, filed October 25, 1937, Ser. No 170,988, in which is disclosed one means and method for securing a long duration recording on a recording element of comparatively short or normal length. In accordance with the invention disclosed in said copending application, the magnetic element, preferably in the form of a tape, is driven through the machine first in one direction and then in the other, a recording being made on the tape during each such trip, and successive recordings being spaced laterally of one another on the width of the tape, a multiplicity of sets of recording coils and pole pieces being provided, one allotted to and positioned opposite each recording lane. These sets of recording coils are used successively as the tape is driven first in one direction and then in the other, so that successive recordings are made on the single tape, one next to the other across the width of the tape. In accordance with the present invention, a multiplicity of recordings is made on adjacent longitudinally extending lanes of the tape, but this is accomplished by shifting the relative position between the tape and the recording coils and pole pieces each time the tape reverses direction, the tips of the pole pieces being only sumciently wide to affect a limited width of the tape on each trip of the tape through the machine, so that there is again provided a multiplicity of successively made recordings extending longitudinally of the tape. It will of course be evident that the recording coils may be stationarily mounted and the tape shifted transversely at the end of each trip past the coils, or the tape may be arranged for travel along a porting panel I5.

fixed line of travel, and the recording coils shifted transversely of the tape a proper distance each time the tape reverses direction. The generic claims broadly covering multiple lane recording are made in the aforementioned copending application, claims in the present application being drawn to a system in which there is relative transverse shifting between the recording coils and tape.

With this preliminary discussion in mind, the invention itself will be most readily understood from the following detailed description of present preferred embodiments thereof, reference for this purpose being had tothe accompanying drawings, in which:

Fig. 1 is a front elevation of a recording machine in accordance with the present invention;

Fig. 2 is a section taken on line 22 of Fig. 1;

Fig. 2a is a detail showing an anchoring means on the end of the recording tape;

Fig. 3 is a section on line 3-3 of Fig.

Fig. 4 is a section on line H of Fig. 3;

Fig. 5 is a fragmentary view looking toward the machine as though viewed from the right in Fig. 3;

Fig. 6 is a detail section on line 6-6 of Fig, 3;

Fig. 7 is a simple, typical wiring circuit for the system;

Fig. 8 is a view similar to Fig. 3 but showing a modification;

Fig. 9 is a view taken as indicated by line 9-9 of Fig. 8, certain arts'being broken away;

Fig. 10 is a perspective view of a typical pole piece;

Fig. 11 is a section on line ll-H of Fig. 2; and

Fig. 12 is a section on line l2l2 of Fig. 2.

'Ihe exempliflcation. of the .invention illustrated in the drawings has a supporting panel l5, preferably, though not necessarily, vertically disposed, and spaced forwardly of supporting panel IS, a vertical panel l6 adapted to carry certain members and serving to encloseportions of the driving gear located forwardly of sup- As here shown, panel I6 is supported from panel l5 by means of supporting brackets or wall members ll (see Fig. 2).

Mounted on and extending through panel [5 as a tubular bearing member l8 having bushings I9 and 20 within which is iournalled spindle 2|, the latter being provided with a reduced portion 22 extending forwardly through an opening 23 in front panel l6.

Tightly mounted on spindle portion 22, immediately forwardly of bushing I9, is a belt pulley 25, and just forwardly of pulley is an equal diameter pulley 26 which is tightly mounted on the inner end of a sleeve 21 which is mounted on a bearing bushing 28 rotatable on spindle portion 22. The outer end of sleeve 21 is supported by a bearing bushing 30 which is rotatable on a portion 3| of spindle 2| reduced to a diameter smaller than that of portion 22. The extremity 32 of spindle 2| is reduced still further, and has tightly mounted thereon an annular member 33 of the same outside diameter as the reduced outer end 34 of sleeve 21. A pair of reels 35 and 36 for the magnetic tape are mounted in concentric, closely spaced relation on member 33 and sleeve: portion 34, respectively. The reels are keyed on said members, as indicated at 31, and are preferably arranged for ready demountability. For example, the hub portion 40 of the reels may be arranged for sliding engagement with members 33 and 34, and may be releasably retained thereon by any suitable spring clamp devices as indicated at 39. A preferred type of reel and mounting, partially indicated in the drawings, is more fully disclosed and claimed in my copending appli cation, entitled "Reel for magnetic recording.

tape, Ser. No. 170,987, filed October 25, 1937.

Each of reels 35 and 36 has a central hub portion 40 to which the magnetic tape M may be anchored, in any suitable manner, and on which said tape is reeled. For example, as indicated in Fig. 2a, the end of the tape may be provided with an anchor piece 4| adapted to be engaged in a key-hole slot 42 formed in hub member 40. Th tape is wound on the hub of reel 35 in such direction that it may extend toward the right, in the aspect of Fig. 1, from the bottom of the roll, as clearly indicated in Fig. 1, the reel thus turning in a counter-clockwise direction, as viewed in Fig. 1, as tape M is fed therefrom, or in a clockwise direction as the tape goes onto said reel. Assuming the tape to be fed from ree1 35, it is taken towardthe right, as viewed in Fig. 1, to pass under and then upwardly from a drive pulley 46. This pulley 46, which is preferably alined with reel 35 (see Fig. 2) is tightly mounted on the reduced extremity of a drive shaft 41 journalled for rotation in bushings 48 and 49 supported by a tubular bearing member 50 mounted on and extending through supporting panel l5, said shaft passing through an opening 5| in front panel member |6. Means for driving shaft 41 will be explained later. Tape M is pressed into driving engagement with pulley 46 by a spring-pressed idler roller 52. This idler roller 52, which engages the tape and presses it against the tread 46a of pulley 46 between pulley flanges 46b, is carried by a yoke 54 furnished with a guide stem 55 which non-rotatably but slidably engages a bracket or support 56 mounted on panel I 6.

From drive pulley 46, tape M passes upwardly through a polarizing and translating magnet unit or tone head 60 to an idler pulley 6|, and after passing over pulley 6|, the tape is taken to inner reel 36. The tape goes on to the upper side of the roll'reeled on reel 36, being wound thereon by counter-clockwise rotation of reel 36 during drive of the tape from reel 35 to reel 36. Of course, when drive pulley 46 turns right handedly, the tape is driven from inner reel 36 over idler pulley 6| and drive pulley 46 is outside reel 35, reels 35 and 36 rotating in a clockwise direction.

The tape may. if desired, be given a twist between pulley 6| and reel 36, in order to enable it to go onto reel 36 more readily, though this is not necessary and the tape is not so illustrated in the drawings.

Mounted on the rearward end of shaft 41 is a belt pulley 66, driven through belt 61 from pulley 63 pinned on a shaft 69 driven through reduction gear set 10 from electric drive motor 1|.

Means are provided for driving inside reel 36 and allowing outside reel 35 to idle when drive pulley 46 is being driven in such direction as to drive tape M from reel 35 to reel 36, and to drive outside reel 35 and allow inside reel 36 to idle when drive pulley 46 is driving the tape in the reverse direction. For this purpose, the aforementioned pulleys 25 and 26 are connected by belts and 96 with pulleys 91 and 98, respectively, arranged for alternate drive from shaft 41 as said shaft is rotated in one direction or the other. As a simple and preferred means to this end, pulleys 91 and 98 are driven through one-way drive clutches, here shown as rollerratchet clutches I00 and IN, respectively, from drive shaft 41, said clutches being arranged to drive alternately as shaft 41 is rotated in one direction or the other. Pulleys 91 and 38 are mounted on the outer ring portions I03 of the roller ratchet clutches, the inner members |04 of the clutches, which are provided with the usual notches I05 and rollers I06, being keyed on shaft 41. As will be evident from Figs. 11 and 12, pulley 96 is driven through roller ratchet clutch |0| when shaft 41 is rotated in a counterclockwise direction, as viewed from the front of the machine, while pulley 91 is driven through roller ratchet clutch I00 when shaft 41 is rotated 91 idles on shaft 41, reel 35 being rotated simply by the tape which is being fed from it. And when pulley 46 is being rotated by shaft 41 and electric motor 1| in a clockwise direction, so as to drive tape M from inside reel 36 toward outside reel 35, outside reel 35 is driven through ,roller ratchet clutch I00, belt 95 and pulley 25 to take up the tape properly, insid reel 36 at this time rotating freely as the tape is drawn therefrom.

The relations of the driving gear should be such that the reel which is acting as the supply reel will not be rotated by the tape at such a speed, as the roll of tape on the reel approaches its minimum diameter, as to drive rearwardly through pulley 25 or 26, as the case may be, at a sufficiently high speed to cause the corresponding pulley 91 or 98 to overtake the inner driven member of its roller ratchet clutch and thus tend to drive said inner member faster than it is being rotated by shaft 41. Any such tendency would of course be relieved by slippage of belts 95 or 96, as the case might be. However, this condition is avoided by properly relating the diameters of pulleys 91 and 98 to pulleys 25 and 26 as well as the diameter of pulley 46 to the diameter ofjthe hubs of the two reels. Preferably, in order to safeguard against this condition, pulleys 25 and 26 are made of slightly smaller diameter than pulleys 91 and 98, and the effective diameter of pulley 46 is no greater than the diameter of the hub portion 40 of the reels. With this arrangement, there is positive assurance that the supply reel cannot drive rearwardly in the manner described. This arrangement also provides a desirable overdrive on the reel which is acting as the take-up reel.

Preferably, pulleys 25 and 26 are provided with.

spring pressed friction shoes 26a-26a, respectively, which serve to prevent overrunning of the reels.

Tone head 60, best shown in Figs. 3 and 4, embodies two rectangular insulation blocks H and III. A pair of headed pins H2 pass with sliding fit through block III and tightly engage block H0. Block III is thus movable toward and from block H0 on pins H2, the opposing faces of the two blocks being in engagement with one another when the device is in operating position. Preferably, pins H2 have hinge joints H3 permitting block III to be swung open from block H0 after being pulled outwardly on pins H2.

This opening arrangement, which is of great convenience in threading the recording tape between the two blocks and in inserting or removing the pole pieces in the device, is disclosed and claimed in my copending application entitled Sound head for magnetic recording machine, Serial No. 170,985, filed Oct. 25, 1937, now Patent No. 2,229,- 326 of Jan. 21, 1941.

As here shown, block H0 is mounted on the outer end of a plug member H6, which is adapted to be removably inserted in a socket member II! mounted on the outer end of a hollow shaft member H9 having a longitudinally sliding fit within a bore I formed in a mounting member I2I secured to panel I5. ShaftI I9 is held against rotation by a key I22 and a keyway I23, all as clearly shown in Fig. 3. Shaft H9 is hollow, as illustrated in Fig. 3 and serves as a conduit for a cable H90. connected to the tone head.

Mounting member I2I is formed with a pair of oppositely extending arms I25 and I26 which curve around opposite ends of the tone head. The ends of these arms are provided with portions I21 having fiat faces I28 coplanar with the meeting faces of sound head blocks H0 and III. Hinged on each of arm portions I2! is a cover plate I30 having a plane surface I3I adapted to meet surface I28. The hinged portion I32 of cover plate I30 is engaged by a flat spring member I33 which yieldingly holds member I30 in face to face engagement with arm portion I21.

The described opposed faces I28 and I3I are formed in each instance with a longitudinally extending groove or way I34a adapted to receive and pass the recording tape. For example, assuming use of a tape of .002" in thickness and .125" in width, this way may be .003" in depth and .126" in width. The way should be only suiiiciently largerthan the cross-sectional size of the tape to permit the tape to be drawn freely therethrough. Arm portion I21 and cover plate I30 may be grooved in such a manner that the depth of this way I34a lies half within each of said members when the members are in face to face engagement, as in Fig. 4 and Fig. 6. The two ways thus provided at the ends of oppositely extending arms I25 and I26 are in alinement with one another, and are located opposite the ends of tone head blocks H0 and III, as illustrated.

The opposed faces H00, and IIIa of blocks H0 and III are formed with a longitudinally extending groove or way I34 adapted to receive and pass the recording tape. This way, which is alined with the aforementioned ways I34a is of the same depth as ways I340, but of greater width. Way I34 may, for example, be approximately greater in width than ways I34a. Blocks H0 and III may be grooved in such a manner that the depth of way I34 lies half within each block when the 'two. blocks are in face to face engagement.

Three pairs of electromagnets are mounted in blocks H0 and III. Thus, a pair of recording or translating electromagnets Rare mounted in blocks H0 and III, with their axes intersecting the center line of way I34. A pair of erasing or polarizing coils E1 and a second pair of erasing or polarizing coils E: are mounted in blocks H0 and III above and below recording coils R, respectively, with their central axes also intersecting the center line of way I34.

Each of the recording and erasing magnets comprises a wound magnetic bobbin I40 provided with a central aperture I4I of rectangular cross section for the magnetic pole piece I42. Bobbins I40 are received within cylindrical magnetic sheath 0a tightly mounted within insulation block H0 or III, as the case may be. 7

Pole pieces I42 (see Fig. 10), of rectangular cross-section, are slidably mounted in apertures MI, and their inner ends are beveled and tapered to an edge preferably not over approximately .003" in thickness and of a dimension at right angles to the tape approximately, or slightly less than, one-half of the width of the tape (assuming two-lane recording). The pole pieces may be formed initially with a comparatively sharp, chisel-like edge I 42a, but byreason of wear on the tape are soon blunted somewhat and operate satisfactorily, with comparatively slow speed of tape, at a thickness dimension of approximately .003" as stated above.

The outer ends of pole pieces I42 are engaged by plunger members I50 pressed lightly against the pole pieces by means of compression springs I5I mounted in housings I52 carried by plates I53 which are mounted on the insulation blocks, as in the manner clearly illustrated in Fig. 4.

In the embodiment of the invention here shown, the pole pieces of each pair of erasing magnets are somewhat offset from one another in a direction longitudinally of way I34, while the recording magnet pole pieces are directly opposite one another, as clearly indicated in Fig. 4.

The tape moving between pulleys 46 and 6| (see Fig. 1) is received within and'guided by ways I32 formed in the ends of arms I25 and I26, and between ways I34a, passes through way I34 formed between recording head blocks II 0 and- I l I. Way I34 within the recording head has been described as of a width greater than that of the tape, and the recording head is accordingly capable of transverse movement relative to the tape. Thus, a recording having been made along one edge of the tape with the recording head positioned, for example, as seen in Fig. 3, then the recording head may be moved toward the right, as seen in Fig. 3, thereby shifting the position of the recording head pole pieces laterally with relation to the tape, after which'a second recording may be made on the tape parallel to and adjacent the first.

Means for so shifting the recording head will now be described. Shaft H9 which supports the recording head extends through an opening I in panel I5, its rearward end being supported by a tubular boss I6I extending within opening I60, said boss I6I being formed on a mounting member I62 secured to the rearward side of panel I5 as by means of screw I63. Secured against member I62 by said screw I63 is a plate I64, the inner surface I65 of which overlies the rearward end of shaft H9. The rearward end portion of shaft portion H9 is formed with screw threads I66 of relatively coarse pitch, and mounted on the screwthreaded portion of shaft IIS, between surface I65 of plate I64 and the opposed surface 'I62a of mounting member I62 is a nut member I61, provided with an extending arm I68 (see Fig. 5). Nut member I61 is confined against axial movement between surfaces I65 and I62a, but is freely rotatable therebetween. It will be evident that rotation of nut member I61 will effect longitudinal travel of shaft I I8 and sound head 60 carried thereby. Threads I66 are of such pitch that operation of shaft I68 through the angular travel indicated in Fig. 5 will move shaft II9 through a distance just suificient to move the sound head from a position in which magnetic tape T (indicated in Fig. 3 in dotted lines) is adjacent one edge of way I34 to a position in which said tape is adjacent the other edge of said way. Accordingly, when operating arm I68 is in one position, the pole pieces of the magnets will be opposite and operate on one half of the tape, and when arm I68 is shifted to its other position, said pole pieces will lie opposite and operate on the other half of the tape. The two operating positions of the sound head are established by stop pins I10 and HI which are engaged by arm I68 when one side or the other of way I34 is adjacent the edge of the tape I guided by fixed ways I34a of arms I25 and I26.

Connected to the swinging end of arm I68 is a link I15, the other end of which is connected to the movable plunger I16 of a solenoid I11. Energization of solenoid I11 moves arm I68 from the full line position of Fig. 5 to the dotted line position of said figure, while a compression spring I18 acting between the ends of solenoid I11 and a flange I19 on link I returns arm I68 to the full position of Fig. 5 when solenoid I11 is deenergized. Thus, when solenoid I11 is deenergized, a recording is made on one half of tape T, while energization of solenoid I11 causes movement of arm I68 from the full to the dotted line positions of Fig. 5, thereby shifting shaft I I9 and sound head 60 sufliciently to move the recording pole pieces over to the other half of tape T so as while contacts 2I6 and 2" are connected by lead 2I8 to power supply 266. It will be evident that when switch S is in the position ilhrstrated in Fig. 7, the field winding 262 of motor II is energized with one polarity with reference to the armature of the motor, and that when member 204 of switch S is moved so as to bring conductor member 205 against contacts 2 and M2 and conductor member 266 against contacts 2I3 and 2 I 4, the polarity of the field with reference to the armature will be reversed, and the motor will therefore run in the reverse direction. The tape is therefore driven through the machine in one direction or the other, depending upon the position of switch S. It may here be noted that While switch 5 y here be simply as a manually operated switch, it may of course be operated automatically as the tape reaches the end of its travel in each direction.

The previously described recording magnets R and erasing magnets E1 and Ba appear in Fig. 7, the windings of each pair of magnets being connected in series, as indicated. As here typically shown, the erasing magnets are energized by direct current, though of course any other suitable type of erasing magnet current may be employed if desired. Thus, series connected-pairs of magnets El. and E: are here shown as connected at one side by leads 220 and 22!, respectively, to one side of a battery 222, the other side of said battery being connected by conductor 223 to the movable arm 224 of a control switch 225. Switch arm 224 is movable between two contacts 226 and 221, contact 226 being connected by wire 22: to recording magnets E1, and contact 221 being connected by wire 226 to recording magnets E2. Thus, when switch arm 224 is moved in one direction, so as to make with contact 226, magnets E1 are connected in circuit with battery 222, and when switch arm 224 is moved in the opposite direction, so as to make with contact 221, magnets E: are connected in circuit with battery 222.

Switch arm 224 is moved between contacts 226 and 221 by a projection 236 on operating to effect a recording on said otherhalf of the v tape.

A typical electrical circuit for the system is shown in Fig. 7. The aforementioned drive motor H for the mechanism is designated by the same posite direction, conductor members 205 and 206 make with contacts 2I I, 2I2 and 2I3, 2, respectively. Contacts 201 and 2I3 are connected to one field winding lead 2I5, while contacts 2I I and 209 are connected to the opposite field winding lead 2I6. Contacts 208 and 2I2 are connected to a lead 2 I1 connected to power supply lead 20I,

. arm I68 (see Fig. 5). When solenoid I11, diagrammatically shown in Fig. 7, is energized, its movable core, which is operatively interconnected with switch arm 224, moves in such manner as to allow said arm 224 to make with con tact 226, thus connecting erasing magnets E1 in circuit and moving the sound head to record on one half of the tape; and when solenoid I11 is deenergized, its core I16 moves under the influence of spring I16 toswingarm I66 in an upward direction, thereby moving switch arm 224 into contact with contact 221, at which time erasing magnets E: are energized and the sound head is positioned to record on the other half of the tape.

In the simple form of the invention here shown, energization of solenoid I11 is controlled by a circuit 235 including a battery 236 and a switch 231.

It is to be understood that when a recording is to be made on either lane of the tape, erasing magnets E1 or E: are connected in circuit, depending upon the direction in which the tape is to run, the erasing magnets which are ahead of the recording magnets for a given direction of the tape being used. These erasing magnets, supplied with direct current from battery 222, produce a magnetic flux through the tape between the erasing magnet pole pieces, and cause the tape to be magnetized to saturation, thereby obliterating any prior recording on the lane of aameci I the tape covered at that time by the erasing pole pieces. The recording coils are at the same time energized by a voice or sound current, producing a varying flux through the tape between the tips of the recording coil pole pieces, and thereby efiecting a magnetization of the lane of the tape covered by said pole pieces, corresponding to'the fluctuations of the voice or sound current. The resulting magnetized sound record on the tape is subsequently reproduced by running the tape between a pair of reproducing magnets which may either be the same magnets used for recording, or may be similar magnets on a reproducing machine. In order to avoid erasing of the record during reproduction, a switch 234 is provided in circuit 223, which is opened during reproduction of the record.

One side of recording magnet R is connected by a conductor 258 to contacts 25l and 252 of a record-reproduce switch 254. A microphone M is connected via leads 255 and 256 across contacts 251 and 258, respectively, of switch 254.

When switch 254 is thrown to record position,

a switch arm 259 makes with contact 258, a switch arm 260 makes with contact 251, and a switch arm 261 makes with contact Switch arm 259, thus connected microphone lead 256, is connected by lead 26 to one end of the primary winding 263 of an amplifier input transformer 264, while switch arm 260, connected to the other microphone lead, is connected by lead 265 to an intermediatetap of the primary of input transformer winding 263. The secondary winding of transformer 264 is connected to the input end of an amplifier 268, typically of the vacuum tube type. Output leads 269 and 218 of amplifier 268 are connected to switch arms 261a and 26l, respectively, then making with contacts 25! and 25la, and are therefore connected across recording magnet leads 258 and 250a. Microphone M is thus connected through switch 254 and amplifier 268 to recording magnets R, so that a speech or music input to the microphone produces a corresponding sound current which, after amplification, flows in said recording or translating magnets R.

When switch 254 is moved in the opposite direction, to reproduce, switcharms 259 and 214' make with contacts 215 and 252, respectively, contact 215 being connected by wire 211 to recording coil lead 250a, and contact 252 being connected by wire 218 to recording coil lead 258. At the same time, switch arms 26: and 26l make with contacts 280 and 28l, respectively, which are connected by leads 282 and 283 to a speaker 284. Switch am 214 is connected by lead 285 to the end of primary transformer winding 263 opposite the end to which lead 262 is connected. Translating coils R are then connected through switch 254 and amplifier 268 to speaker 284, so that if a tape T having a previ ous recording thereon is run in proper direction through the machine, with erasing circuit switch 234 open, the recording on whichever lane of the tape is positioned opposite the pole pieces of magnets R will produce corresponding sound currents in said magnets R, which will flow in the described circuiting and be reproduced at speaker 284.

To make a recording, switch 254 is thrown to record position, erasing circuit switch 234 is closed, motor reversing switch S is placed in proper position to cause the tape to be driven in whichever direction is desired, switch 231 is either placed in open or closed position, depending upon which lane of the tape is to be recorded on first, and line switch 290 is then closed. Tape T will then be driven ahead, its past history will be obliterated by the erasing or polarizing magnets located ahead of the recording magnets, and an amplified voice current, flowing in recording magnets R. due to a voice input to microphone M, will be recorded on the lane of the tape which is then in alinement with the recording magnet pole pieces. When the tape has thus been run through the machine, switch S is reversed to cause the tape to be driven in the reverse direction, and switch 231 is operated to shift the recording head so. as to move its pole pieces over into alinement with the other half of the tape.

lane of the tape. Thus two adjacent recordings are made on the tape, which, as here described, extend in directions contrary to one another. It will of course be evident that if desired, the two recordings may extend in the same direction along the tape simply by running the tape back to its beginning point at the end of the recording on the first lane, and then starting the second recording on the same end of the tape as before.

Fig. 8 is similar to Fig. 3 but shows a modification, in which the recording head is stationary and the tape guide arms move transversely of the tape, so as to efiect the necessary relative movement between recording head and tape by moving the tape in a transverse direction rather than moving the recording head. The recording head, designated at GM, is again made of blocks H8 and III, which may be identical to the recording head blocks of the previously described form of the invention, and which may be understood to have polarizing and translating magnets and a way for the tape all identical to the corresponding members in the previously described form. Block H0 is mounted on the outer end of a plug member 3), adapted to be removably mounted in a socket member 3| I mounted on the outer end of a hollow post 3l2 mounted on panel l5, the hollow within post 3l2 receiving the cable 3l3 comprising the conductors connected to the magnets within the recording head. Tape guide members 3l5, exactly like those described in connection with Figs. 3 and 4, are mounted on;

the ends of arms M6 and 3H, the latter supporting said guide members opposite the two ends of the recording head, as indicated,.and being themselves carried by a shaft member 320 having a longitudinally slidable fit within a bore 32I formed in mounting member 322 secured to panel 15. The rearward end of shaft member 328 is A formed with screw threads 324 of coarse pitch,

and engaging the screwthreaded portion of the shaft, between mounting member surface 325 and a cover plate 326 secured to mounting member 322, is a nut member 321 similar to nut l61'in the form of Fig. 3, said nut member being operated by an extending arm 328 exactly as described in connection with the previous form of the invention.

Aside from the modifications now described, the form of Figs. 8 and 9 may be exactly similar to the previously described form of the invention,

, movement of nut 321 by means of arm 328, ac-

ings made thereon will extend along adjacent, non-overlapping lanes of the tape, so that a multiplicity of adjacent recordings may again be made ona single magnetic tape.

Certain specific illustrative forms of the invention have now been described, although it will be understood that the description here given is for illustrative purposes only, and that various changes in design, structure and arrangement may be made without departing from the spirit and scope of the invention or of the claims appended hereto.

I claim:

1. In a magnetic sound recording system, the

combination of a fiat magnetizable tape, a sound head comprising a pair of erasing magnets, a pair of translating magnets, and another pair of erasing magnets, arranged in tandem, the magnets of each of said pairs having pole pieces between which .said tape may be driven and which are all adapted and positioned to coact selectively with a limited width lane of the tape, guide means adapted to guide said tape to travel between the pole pieces of said pairs of magnets, means for driving said tape in, either direction, electric circuiting for energizing the erasing magnets, switching means for connecting said circuiting to that pair of erasing magnets which is positioned ahead of the translating magnets for each direction of travel of the tape, and means for efi'ecting relative transverse movement between said sound head and said tape guided by said guide means, whereby recordings may be made on diflerent, non-overlapping longitudinally extending lanes of said tape.

2. In a magnetic sound recording system, the combination of a flat magnetizable tape, a sound head comprising a pair of erasing magnets, a

pair oi. translating magnets, and another pair of erasing magnets, arranged in tandem, the magnets of each of said pairs having pole pieces between which said tape may be driven, and which are all adapted and positioned to coact selectively with a limited width lane of the tape, guide means adapted to guide said tape to travel between the pole pieces of said pairs of magnets, means for driving said tape in either direction, electric circuiting for energizing the erasing magnets, switching means for connecting said circuiting to that pair of erasing magnets which is positioned ahead of thetranslating magnets for each direction of travel of the tape, and means for shifting said sound head in a direction transversely of said tape, whereby recordings may be made on diil'erent, non-overlapping lanes of said tape.

3. In a magnetic sound recording system, the combination of a flat magnetizable tape, a sound head comprising a pair of erasing magnets, a pair of translating magnets, and another pair of erasing magnets, arranged in tandem, the magnets of each of said pairs having pole pieces between which said tape may be driven, and which are all adapted and positioned to coact selectively with a limited width lane of the tape,

guide means adapted to guide said tape to travel between the pole pieces of said pairs of magnets, means for driving said tape in either direction, electric circuiting for energizing the erasing magnets, switching means for connecting said circuiting to that pair of erasing magnets which is positioned ahead of the translating magnets for each direction of travelof the tape, and means for shifting said guide means and tape relatively to said sound head in a direction transversely of the tape, whereby recordings may be made on difierent, non-overlapping longitudinally extending lanes of said tape.

4. In a magnetic sound recording system, the combination of a fiat magnetizable tape, a sound head comprising a pair or erasingmagnets, a pair of translating magnets, and another pair of erasing magnets, arranged in tandem, the magnets of each of said pairs having pole pieces between which said tape may be driven and which are all adopted and positioned to coact selectively with a limited width lane of the tape, guide means adapted to guide said tape to travel between the pole pieces of said pairs of magnets,

means for driving said tape in either direction, means for reversing the direction of longitudinal movement of the tape at a given point in its travel, and electric circuiting including switching means operable to energize selectively that pair of erasing magnets which is positioned ahead of the translating magnets for each direction of travel of the tape, said switching means being automatically operated by virtue of the reversal of the direction of travel of the tape at said given point in its travel, and means for eiIecting relative transverse movement between said sound head and said tape guided by said guide means, whereby recordings may be made on difierent, non-overlapping longitudinally extending lanes of said tape.

5. In a magnetic sound recording system, the combination of a flat magne'tizable tape, a sound head comprising a plurality of pairs of erasing and translating magnets, arranged in tandem,

between the respective magnets of which the tape may successively pass, said pairs of magnets including a pair of erasing magnets positioned ahead of a pair of translating magnets for each of the two directions of travel of the tape, the magnets of each of said pairs having pole pieces adapted and positioned to coact selectively with a limited width lane of the tape, guide means adapted to guide said tape in its path between the magnets of said pairs of erasing and translating magnets, means for driving said tape in either direction, electric circuiting for energizing the pair of erasing magnets positioned ahead of the pair of recording magnets for each direction of travel of the tape, and means for effecting relative transverse movement between said sound head and said tape guided by said guide means, whereby recordings may be made on diflerent, non-overlapping longitudinally extending lanes of saidtape.

HERMAN S. HELLER.

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