US2030973A - Method of and apparatus for electrically recording and reproducing sound or other vibrations - Google Patents

Method of and apparatus for electrically recording and reproducing sound or other vibrations Download PDF

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US2030973A
US2030973A US556743A US55674331A US2030973A US 2030973 A US2030973 A US 2030973A US 556743 A US556743 A US 556743A US 55674331 A US55674331 A US 55674331A US 2030973 A US2030973 A US 2030973A
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tape
recording
electrical impulses
reproducing
current
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US556743A
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Duston Merle
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor

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  • An object of my invention is to simplify the recording and reproducing of electric impulses by eliminating the use of light sensitive materials and any necessity for the delevopment or xation of the same.
  • Another object of my invention is the elimination of the use of costly and delicate optical apparatus in the recording system.
  • Another object of my invention is to simplify and increase the emciencyof the reproduction of the recorded sounds or currents.
  • Another object' of my invention is to provide a system whereby the same machine may be used for recording and immediately reproducing the recorded signals for monitoring and other purposes.
  • a further object of my invention is to provide an apparatus and method for recording light waves, sound waves, or other mechanical vibrations and automatically reproducing therecorded signals after al predetermined lapse of time.
  • a further object of my invention is to provide an apparatus in which the recording may be done at one time and the reproducing immediately thereafter or at any desired subsequent time.
  • Still another object of my invention is to provide a method and apparatus for recording mechanical vibrations by producing indices on a tape and subsequentlytransforming these indices into an accurate reproduction of the mechanical 'vibrations.
  • Another object of my invention is to provide a means for recording sound Waves or other mechanical vibrations by producing indices on a tape which can be kept for long periods of time without substantial deterioration.
  • a further object of my invention is to provide a means for recording light impulses, sound waves, or other mechanical vibrations by producing visual indices on 'a tape which can be immediately used for analyzing the various frequency characteristics of the vibrations.
  • Figure 1 is an assembled View. of a combined recording and reproducing mechanism
  • Fig. 2 is a schematic diagram of an amplifier
  • Fig. 3 is a view, partly in section, taken on line 3--3 of Fig.. l;
  • Fig. 4 is an elevation of a modified form of recording mechanism
  • Fig. 5 is a view, partly in section, taken on line m 5 5 of Fig. 4; i
  • Fig. 6 is a view of another form of recording mechanism
  • Fig. 7 is a side view of the recording arm of Fig. 6;
  • Fig. 8 is an end view of the recording arm of Fig. 6;
  • Fig. 9 is a diagram of a battery-operated recording apparatus
  • Fig. 10 is an enlarged view of the recording arm shown in Fig. 1;
  • Fig. 11 is a section on line II--I I, Fig. 10;
  • Fig. 12 shows a fragment of a tape partly used.
  • a suitable frame I is shown in Fig. 1 on which is'supported a supply reel 2 and a receiving reel 3.
  • a vtape 4 for receiving marks or indices, carrying a suitable chemical compound (as more fully explained hereafter) is fed from the supply reel 2 between a xed contact 5 and a movable contact 6 of a recording mechanism A, and then, if it is desired to immediately reproduce the recorded signals, is lead over an exposure guide I -of the reproducing mechanism C.
  • the tape then passes between the rollers 8 and 9 to the receiving reel 3.
  • a motor I0 is provided to furnish power and operate preferably through any suitable variable speed gear reduction II todrive the shaft I2 on which is mounted a. pulley I3.
  • Suitable belts I4 and I5 are driven from a portion of the pulley I3 and pass over pulleys I6 and I1 connected to the shafts I8 and I9 which carry the reels 2 and 3 respectively, the shafts I6 and I1 being suitably supported in the frame.
  • the crossed driving belt 20 receives power from pulley I3 for suitable pulley connection.
  • the motor III is pref.- erably an electric motor of theconstant speed type but may be any suitable driving. mechanism.
  • the tape 4 In order that the tape 4 may be passed at constant speed through the apparatus for recording or reproducing, the tape is driven by the constant speed roller 9 ⁇ and the companion roller 8 resiliently mounted to press against the tape.
  • the belt I4 operating between the pulley I3 and the receiving reel 3 is so mounted on the pulleys I3 and I6 that it can slip and only revolves the reel 3 at a suicient rate of speed to keep a suitable tension on the tapeas it comes from the constant speed rollers 8 and 9.
  • the tension on the tape from the constant speed rollers revolves reel 2 and unwinds the tape from the reel, but in order to keep a suitable tension on the tape any suitable retarding mechanism may be provided, and in the mechanism shown the belt I5 is mounted between pulleys I3 and I1 so that p it tends to drive the reel in the opposite direction, but is sufliciently loosely mounted to slip on the pulleys and act as a brake to keep the desired tension on the tape.
  • the belt I5 which is provided with more tension than the belt I4 will act as a driving belt for rewinding the tapeon the supply reel 2, and in this case the belt I4 acts to retard the reel 3 to preserve the desired tension on the tape.
  • the constant'speed pulley 8 is carried at one end of the arm 2
  • Shaft 22 is mounted on frame I, and a screw tensioning device 23 is also mounted on the frame for adjusting the arm 2
  • the fixed contact 5 is mounted on an insulating panel 25, and is preferably of brass but may be of any good electrically conducting material, and is preferably provided with a curved, polished surface 26 to facilitate the passage of the tape thereover and to provide a convex surface.
  • a movable contact holding arm 21 is mounted for pivotal movement on the pivot member 23 carried by the insulating panel 25.
  • a balance weight 29 which may be adjusted along the threaded portion 36 lof the contact arm.
  • Carried by the arm 2 is a collar 3l preferably of insulating'material.
  • ⁇ spring 32 is connected to one side of the collar, the other end of the spring being carried by adjusting screw 33 which passes through an aperture on the threaded stud 34 and is adjustable by means of a threaded nut 34a which bears against the stud 34.
  • the stud 34 is mounted to the panel 25.
  • a yoke 35 is also carried by the collar 3
  • a stud 36 is similarly carried by the panel 25 through an aperture in which the screw 31 is passed, the screw being connected to the yoke 35 by means of a tension spring 38.
  • a nut 39 engages the threaded endA of the screw 31 and bears against the stud 36 so that the screw may be adjusted.
  • a contact holder 40 is pivotally secured to the free end of the arm 21 by means of a screw 4I passing through the members 42 of the contacty holder and arm 21. At the outer end of the contact holder 40 a. slot 52 is provided to receive a contact blade 6. Secured to the holder 40 is a cap portion 43 in which a set screw 44 is threaded so that the set screw may be adjusted to clamp the blade 6 tightly in the holder.
  • An amplifier 45 which may be of the type shown in Fig. 2, is provided with suitable terminals 46 and 41. From the terminal 46 a lead 56 electrically connects terminal 46 to the fixed contact 5. The lead 5I connects the terminal 41 through the arm 21 to the movable contact 6.
  • the contact 6 is preferably a. thin. loch blade Mounted of any good electrical conducting material, such as a platinum alloy, steel, phosphor bronze or the like. It should be of such material that it will resist the wear due to the frictional engagement of the tape and which will stand up under the action of electrical current, and not be readily attacked by the chemical compounds carried by the tape.
  • the blade 6 should be as thin as practicable and still be sufliciently rigid to resist deformations due to the forces acting thereon by the passing of the tape, and the pressure between it and the xed contact 5.
  • Steel blades as thin as one and one-half mills have been successfully used. As the blade wears it may be adjusted in the slot 52 and reset by the set screw 44 to be rigidly held in the contact holder ⁇
  • the width of the bladel may vary within wide limits dependent upon the current density used, the resistance of the tape and the width of record desired for reproduction purposes. A blade of one-eighth inch width has given good results with the above described apparatus.
  • the moment of inertia of the arm 21 about the pivot 28 is adjustable to obtain the desired engagement with the tape so that excessive vibration of the contact 6 is prevented.
  • the tension on the springs is also adjustable to cooperate with the moment of inertia as determined by the weight and at the same time regulate Ithe pressure of the contact 6 upon the tape 4 and give the arm 521 a natural period most suitable for recording the impressed signals.
  • the tape 4 may be passed directly to the constant speed .contact rollers 6 and 9 or over any suitable intermediate roller or guide between the recording mechanism and the constant speed rollers 8 and 9.
  • the reproducing mechanism shown in Fig. 1 consists of a concentrated lament lamp 55 and lens system 56 of the type used in sound film reproductionjor producing a narrow slot image.
  • the lamp and lens system is used in my apparatus for concentrating the light on the tape 4 as it passes over the Vexposure guide 1 through a slotted aperture 51 in the wall of the compartment.
  • the light is reflected from the tape 4 into a suitable light sensitive device such for example as a photo-electric cell 58, the resistance of which is thereby caused to vary in response to the variations in intensity of the'reected light, due to indices or markings recorded upon the tape 4.
  • the Variations in resistance are translated into voltage variations and amplied in the usual manner 'by a suitable amplifier indicated at 59.
  • the lamp 55 is supplied with current in any suitable manner such as by the battery 55a or by a transformer and lter or rectier.
  • the lamp 55 and lens system 56 and the photo-electric cell are preferably enclosed in suitable compartments so that unwanted light does not reach the tape 4 orthe photo-electric cell.
  • any means of projecting a concentrated band of light on the tape 4 may be used, such as a plate having a narrow aperture through which the light passes, and placed directly in front of the tape, and between it and the light source and a light sensitive device responsive to variations in intensity of light, such as a suitable photo cell.
  • the light projected on the tape preferably should be a band at least as narrow as the finest width of the finest division recorded on the tape 4 in order to secure faithful reproduction of the highest frequency recorded.
  • is mounted for rotation on the fixed pivot 66 which is mounted on ⁇ an insulating frame 61.
  • the roller 88 is mounted for rotation on the contact arm 68 which is rotatably mounted on the pivot 69, which is similarly mounted on the insulating frame 61.
  • Adjustable mechanism is provided for swinging the arm about the pivot 69 to move it toward or away from the tape 4 to adjust the pressure of the rollers upon the tape.
  • the mechanism for making this adjustment comprises a screw 18 which passes through the threaded aperture in the stud 1
  • the screw 10 is provided with a collar 12 so that the compression spring 13 is held between the screw and the arm -68 to maintain a yielding pressure, whereby irregularities in the tape 4 can be compensated for.
  • the arm 68 has a cut out portion to engage spring 13. In order to move the roller 68 away from tape 4 a tension spring 15 is carriedY between arm 68 and stud 16.
  • rollers are of small diameter and presentv substantially a line contact to the tape 4 so that the fine markings due to rapidly varying electrical impulses may b ⁇ e recorded on the ⁇ tape.
  • Figs. 6, '1 and 8 show still another modified form of recording mechanism.
  • the tape 4 passes over a fixed contact 80.
  • the contact member 8l is attached to a movable arm 82 which' is adapted to be raised and lowered by the action of the moving member 83 of a phonograph pickup or recorder 84 which is adjustably secured to the lever arm 85 by screw 86 engaging with the back of the recorder housing.
  • a tension spring 81 is attached to lever 85 at one en d and to a securing means 88 at the other end.
  • An adjusting screw 89 working through stud 98 carries a conn ector 9
  • An adjusting 'nut 92 is provided to hold the screw in adj usted position.
  • the spring 81 and the screw 89 provide a means for accurately positioning the arm 85 so that the movable contact member 8
  • the lever arm 85 is rotatively connected to insulating panel 93 by shaft 94. Fixed contact 88, stud 98,
  • One terminal of a source of direct current potential such as a battery or generator, is connected to lead 91 and connected to arm 82 through a very flexible lead' 98.Y
  • the other terminal of such source is connected to fixed contact 8 8 through lead 99.
  • the fixed contact 88 is insulated from the rest of the circuit and is similar in forml and function to the contact 5, Fig. l.
  • is secured to the arm 82l and is preferably thin for sharply defining the marks or cially suitable for recording the ordinary code signals, or any signal not requiring exceedingly fine graduations of frequency or tone.
  • Fig. 2 shows diagrammatically an electrical system adapted for recording or reproducing in connection with my invention.
  • a microphone amplifier as illustrated has a pick-up means for use when recording sound waves.
  • is a. three element thermionic valve ⁇ of the heater type cornmonly having an amplification factor .'1 to l0.
  • VT2 is a four element thermionic valve of the heater type having a screened plate.
  • VT3 is an output thermionic valve of large capacity.
  • 85 of VI2 is directly connected to the plate
  • 88 of VI3 isA connected through the milliammeter
  • the circuit shown in this figure is that of a direct connected amplifier differing from others of this type mainly in the values of the resistance and capacities used, which values are given below by way of example.
  • ance having a value of 25,000 ohms.
  • Variable resistance I2, inseries with resistance I I3, has a maximum value of about 500,000 ohms.
  • 3 is a fixed resistance of 500,000 ohms and is connected at one end to resistance
  • 4 is a grid biasing resistance for the valve'v VT2 and has a value of 25,000 ohms.
  • 5 is a. potentiometer having a resistance of about 400 ohms.
  • 6 is a resistance of 5,000 ohms and resistance
  • 1 has a value of 15,800 ohms.
  • Resistance I8 has a value of 10,000 ohms and resistance
  • 9 has a value of about 250,000 ohms,and may be variable.
  • have a value of about a half a micro-farad each.
  • 23 are filter condensers, and have values of one microis a grid biasing resistfarad and two micro-farad capacity, respectively.
  • 21 has a primary winding adapted to the voltage and frequency of the circuit from which it is desired to draw power.
  • 21 is also provided with three low tension windings lighting the filaments of the various valves employed in the amplifier and the high tension winding for use in conjunction with the rectifier valve
  • 28 is a full wave rectifier which is used as a half wave rectifier by having its plates connected as shown in Fig. 2 for the purpose of obtaining an increased output.
  • 29 should have a value of about 30 henries inductances.
  • 30 is provided so that if desired, a loud speaker for direct monitoring purposes may be connected between the terminal
  • Fig. 9 diagrammaticailyy another system for supplying the varying electrical impulses to the recording contacts MD, SM between which the tape 4 passes. These contacts are simlar to those heretofore described.
  • the signal to be recorded is supplied to the tube VT4, through audio amplifying ltransformer
  • the current passes from the battery
  • 45 furnishes a suitable negative potential to the control member of the tube VT4 through the secondary Ywinding of the audio frequency transformer M2.
  • the potential of the control member relative to the lament can be adjusted by potentiometer Ia.
  • 46 supplies the plate current to the tube VT4 through the contact members
  • Incoming signals are impressed upon the control member of the tube VT4 by means of the audio frequency transformer or other means whereby the current in the plate circuit is caused to vary in accordance with these signals.
  • cause marks or indices of different intensities to be formed upon the tape by the action of the current, proportional in intensity and frequency to the impressedA signals.
  • Fig. 9 The simplified form shown in Fig. 9 is especially convenient ⁇ for recording telegraph messages, wherein the familiar dot and dash system is used.
  • a record receiving element which is ccmposed of a material which will carry chemicals reactive to the passage of electric current, and on which indices can be progressively recorded.
  • a convenient form for such an element is that of a band or tape.
  • the band or tape it is desirable for the band or tape to have a smooth surface so that the movable electrode may readily maintain substantially uniform relation thereto.
  • a. rag paper having a smooth calendered surface, cr a sulphite paper not heavily lled or glazed, may be used.
  • the tape is treated or impregnated, preferably with a. chemical solution which will react, upon the passage of an electric current between suitable 'contact electrodes, to produce a sexies of marks or indices, such as dots or lines, corresponding to the frequency and intensity of the electric current impressed on the tape.
  • a sexies of marks or indices such as dots or lines, corresponding to the frequency and intensity of the electric current impressed on the tape.
  • a fragment of tape 4 with such marks or indices thereon is shown in Fig. 12.
  • a suitable bath for treating the tape may be made with 100 parts of water, parts of potassium ferro cyanide and 1 part of potassium cyanide.
  • Theftape may be pressed to remove the excessive moisture, or dried, or otherwise conditioned. It is more convenient for use and for handling to have in the tape'only a low moisture content. I have found that the moisture content of the tape may vary over wide limits, from the almost normal content of paper of about 10% to a nearly saturated condition. However, as stated above, for practical purposes the low moisture content is more desirable.
  • potassium ferro cyanide and potassium cyanide in the impregnating bath gives a tape upon which a clear, colored series of indices, such as dots or lines, may be formed by subjecting the tape to a varying electric current.
  • the potassium cyanide seems to be of benefit in the solution, in that the dots or lines appear to be more sharp and defined when this is used, and this may be because the potassium cyanide acts as a solvent for minute portions of the decomposition product at the edges of the dots or lines formed by the' action of the electric current on or roll and, as shown in Fig. 1, fed from the reel i 2 ⁇ over the xed contact 5 and under the movable contact 6.
  • the speed .of feeding the tape is prefv
  • I can use speeds as low as 41/2 (inches) per second, but it is usually preferable, for the best results, to use somewhat' higher speeds to bring out the peculiar characteristics
  • the speeds should preferably be somewhat higher I have produced satisfactory music recordings with speeds no higher than 12 inches to 14 inches perrsecond.
  • the optimum speed of recording is dependent, not only upon the speed and intensity of the current, and the reaction speed of the chemicals used to treat the tape, but also upon the quality of the results which it is desired to obtain.
  • heat' is liberated at the contact point when recording, and it may be that this liberation of heat facilitatesthe recording.
  • the heating may be regulated by varyingthe signal intensity, the amplier controls or the output impedance of the amplifier or by other well known means.
  • the grid of VTI When no signal is acting on the. apparatus, the grid of VTI is suiciently negative with respect to the cathode so that the current flowing in the plate circuit is small.
  • 3 is, therefore, small, and grid
  • 9 is, therefore, larger than normal
  • 01 of VT3 is more negative than normal with respect to the filament
  • the current in the plate circuit of VTI willincrease, the current in the plate circuit of VT2 will decrease, and the current through the plate circuit of VT3 and the treated tape will increase, causing a line on the tape, the width of which is proportional to the time of duration of the signal or positive condition of the grid of VTI, and the intensity of which is proportional to the intensity of the current through the tape.
  • a rapidly varying electro-motive force such as that resulting from a succession of sound waves applied to the microphone '
  • 01 of the vacuumrw tube VT3 are of 4suflicient intensity to swing the gridpotential to a positive value
  • 09 indicates these variations and furnishes a criterion of the character of the record being made upon the tape. It sometimes happens that the tape has what might be termed a.v threshold value of current, so that a current of sufficient intensity must be applied to the tape before any record is made.
  • the normal direct current Vcomponent of the plate current of the valve VT3 is usually sulcient for this purpose, but in case a larger direct current component is required, the plate current of the valve VT3 may be increased by connecting a resistance, as
  • nected amplifier operated from an alternating current source it is to be understood that this invention is not limited to the type of amplifier shown, for example, a transformer coupled amplifier or a resistance capacity coupled amplifier operated either from dry batteries, accumulators, or by proper rectifying means from an alternating current source may be employed.
  • my invention furnishes a method of introducing a delay between the production of speech or music and the reproduction of the same. For instance, if -it be desired to reproduce the speech or music shortly after its production, and
  • the length of tape between the recording mechanism and the reproducing mechanism is 14 inches and the tape is running at the rate of 14 inches per second, a delay of one second between the recording and the reproduction of the sound will occur. This delay will occur while the tape is traveling from the recording point to the reproducing point. This time obviously may be varied by changing the distance between the recording and reproducing points to obtain. the desired amount of delay.
  • Afurther advantage of this device lies in its ability to render signals or messages unintelligible in transmission. This may be accomplished either by running the tape with indices recorded thereon, backward through the reproducing devicey for transmission, receiving and recording on another tape, and running that tape backward through a reproducing device for intelligible reception of the signals as messages, or by running the tape through the reproducing device and transmitter at a rate' of speed sufliciently high to prevent intelligible reception and then receiving and recording at a rate of speed corresponding tothe transmitting speedgand reproducing the message by running the tape at a lower rate of speed.
  • the moisture content is substantially immaterial, an'd that the tape may be wound on reels, rolls, or the like, and stored for long periods of time until it is desired to use it for'reproduction.
  • a relatively narrow tape such as one-half inch, may be used, and 1 that a large amount of recording Will be relatively light and may be easilystored and transported. It may be noted, however, that a tape sufficiently wide to have impressed thereon a plurality of series of indices by passing the tape successive times through the recording mechanism may be used.
  • Apparatus for recording electrical impulses which comprises, in combination, a movable tape carrying a substance adapted to react to the passage of an electric current therethrough, a thermionic valve or valves, means for applying varying voltages to the thermionic valve or valves, means coacting with the movable tape forimpressing the resultant varying electrical output of the thermionic valve or valves thereon, said means comprising electrodes, one of which is a thin blade disposed transversely of the tape, and means for moving said tape, whereby successive lines are produced on the tape transversely thereof, each line being produced by a single electrical pulsation.
  • Apparatus for recording and reproducing ⁇ Soundwaves in the audible range which comprises, in combination, a movable tape carrying a substance adapted to react to the action of an electric current, a thermionic valve, means for receiving sound waves and transforming them into electrical impulses and for subjecting the control member of said thermionic value to sai-d impulses, means for moving the tape, means for 'impressing the electrical output of said valve on successive portions of the tape to form a series ci indices, means .for impinging a light beam upon indices of the moving tape and reflecting the light into a light sensitive device of a type.
  • Apparatus for recording and reproducing sound waves in the audible range which comprises, in combination,v a movable tape carrying a substance adapted to react to the action of an electric current, a thermionic valve, means for receiving sound waves and'transforming them a into electrical impulses and for subjecting the control member of said thermionic valve to said impulses, means for moving the, tape and means for impressing the electrical output of said valve on successive portions of the tape in the form of transverse lines of materially greater length than Width, and means controlled 'by said tape for producing electrical impulses corresponding to those impressed on the tape and for transforming these electrical impulses into sound waves corresponding to those producing the electrical impulses previously impressed on the tape.
  • a method of recording electricalimpulses upon a tape carrying a substance adapted to react to the effect of electric current thereon which consists in applying varying volt-ages to a thermionic valve or valves, impressing the resultant varying electrical output of said valve or valves on successive portions of said tape to form ne transverse lines proportional in spacing and intensity to the variation of the current in frequency and intensity while moving the tape at a substantially uniform speed and thereby causing successive portions of the moving tape to receive the eiiect of the electrical impulses impressed thereon and to be differentiated from other portions of the tape.
  • a method of recording electrical impulses on a tape 'carrying a substance adapted to react to the effect of electric current thereon which consists in applying varyng voltages to a thermionic valve or valves, feeding the tape at a substantially uniform speed in proper relation to electrical contacts to receive electrical impulses therefrom, impressing the resultant varying electrical output of said valve or valves on said tape to form successive fine transverse lines of materially greater length than width and proportional in spacing and intensity to the varying electrical output of said valve or valves while the tape is moving relative to the contacts, and thereby causing portions of the moving tape to receive the effect of the electrical impulses impressed thereon and to be differentiated from other portions of the tape.
  • a method of reproducing mechanical vibrations which consists in transforming-said vibrations into electrical impulses, applying the electrical impulses to a thermicnc valve, impressing the resultant varying electrical output of said valve on portions of a tape, carrying a substance adapted to react to the effect of electric current thereon, to cause successive indices to be produced on said tape, causing a light beam to im ⁇ pinge upon said indices on the moving tape and to be reflected into a light sensitive device of a type capable of transforming light variations into electrical impulses, and transforming these electrical impulses into mechanical vibrations ofk substantially the same frequency and intensity as those originally transformed into electrical impulses.
  • a method of reproducing mechanical vibrations which consists in transforming said vibrations into electrical impulses, applying the electrical impulses to a thermionic valve, moving at a uniform rate a tape carrying a substance adapted to react to the effect of electric current, impressing the resultant varying electrical output of said valve on portions of said tape, to cause l successive indices to be produced on said tapeg ⁇ and reproducing from said indices the recorded signal after a predetermined lapse-of time.
  • the electrodes including a .thin blade mounted transversely of the tape, said electrode being mounted for yielding movement relative to the tape so that the electrode ⁇ may have a natural period most suitable for recording the impressed signals, whereby transverse indices of relatively fine gradations corresponding to the basic frequencies and harmonics of the sounds being recorded are produced on the tape.
  • Apparatus for recording electrical impulses which comprises, in combination, a tape carrying a substance adapted to react to the action of an electric current, said tape having such a relatively low moisture content that it appears dry, a thermionic valve, means for moving the tape,
  • Apparatus for recording and reproducing sound waves in the audible range which comprises, in combination, a movable tape carrying a substance adapted to change in color from the eiect of electric current thereon, means for receiving such sound waves and transforming them into electrical impulses, an electrical amplifying system including one or more thermionic valves, means for applying said electrical impulses -to the amplifying system, electrodes disposed transversely of the tape on opposite sides thereof connected to receive the resultant varying electrical output of the amplifying system, means for moving said tape between said electrodes whereby discolorations are produced on successive portions of the tape transversely thereof of materially greater length than width and varying in frequency and intensity with the variations in frequency and intensity of the original sound, means for impinging a light beam upon said indices'of the moving tape, and means for passing the resultant varying reflectedlight into a light sensitive device of the type capable of transforming light variations into electrical impulses, and means for transforming these electrical impulses into sound Waves, whereby vocal
  • ' consists in applying varying electrical impulses to a thermionic Valve, applying the output of the valve to an electro-magnetic member capable of vibrating in response to varying electrical impulses and having a thin recording blade electrode, feeding 'thetape at a substantially uniform speed over a stationary electrode spaced from the first electrode, and applying direct current across said electrodes and through the tape disposed therebetween, whereby the eect of the electrical impulses impressed upon the valve are impressed on the tape in the form of transverse lines of greater length than Width.

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Description

Feb. 18, 1936. M DUsToN 2,030,93
METHOD OF AND APPARATUS FOR ELECTRICALLY RECORDING AND REPRODUCING SOUND. OR OTHER VIBRATIONS Original Efild Aug. 13, 1931 4 Sheets-Sheet INVENTOR Meri@ Euston ATTORNEYS Feb. 18, 1936. M. DUsToN 2,030,973
METHOD OF AND APPARATUS FOR ELECTRICALLY RECORDING AND REPRODUCING SOUND OR OTHER VIBRATIONS Original Filed Aug. 13, 1931 4 Sheets-Sheet 2 INVENTOR MerI/e Euston BYMMMGX ATTORNEYS Feb.1s,1936. M DUSTON 2,030,973
METHOD OF' AND APPARA'US FOR ELECTRICALLYRECORDING AND REPRODUCING SOUND OR OTHER VIBRATIONS Original Filed Aug. l5, 193,1 4 Sheets-Sheet 3 lll la .'65v
INVENTOR` Merle Baston ATTORNEYS Feb. 18, 1936. M. Dus'roN 2,030,973
METHOD .OF AND APPARATUS FOR'ELECTRICALLY RECORDING' AND REPRODUING SOUND OR OTHER VIBRATIONS Original Filed Aug.l 13, 1931 4 Sheets-Sheet 4 /454 Alllulullllhwk IIIIIIIIIIIIIIUIHIHII||HIHHI|IIIIHINIIIINHIHIIllllllllIHIIIIIIHIIIIIIIHEIHHIIIIIIIIlllllllllllllllllHIHII|l|llllMmmm INVENTOR Merle Huston, BY
AATTORNEYS Patented Feb. 1s, 193e Y UNlrD STATES ATENT FFHCE Merle Duston, Detroit, Mich.
Application August 13, 1931, Serial No. 556,743 Renewed August 2, 1934 21 Claims. (Cl. 179-1001) pared tape, without the use of any intermediate 1 apparatus, such as a device for causing the electric current to Vary the intensity or direction of a. beam of light, as is commonly used in record-f ing systems at present in use.
An object of my invention is to simplify the recording and reproducing of electric impulses by eliminating the use of light sensitive materials and any necessity for the delevopment or xation of the same.
Another object of my invention is the elimination of the use of costly and delicate optical apparatus in the recording system.
Another object of my invention is to simplify and increase the emciencyof the reproduction of the recorded sounds or currents.
Another object' of my invention is to provide a system whereby the same machine may be used for recording and immediately reproducing the recorded signals for monitoring and other purposes.
A further object of my invention is to provide an apparatus and method for recording light waves, sound waves, or other mechanical vibrations and automatically reproducing therecorded signals after al predetermined lapse of time.
A further object of my invention is to provide an apparatus in which the recording may be done at one time and the reproducing immediately thereafter or at any desired subsequent time.
Still another object of my invention is to provide a method and apparatus for recording mechanical vibrations by producing indices on a tape and subsequentlytransforming these indices into an accurate reproduction of the mechanical 'vibrations.
Another object of my inventionis to provide a means for recording sound Waves or other mechanical vibrations by producing indices on a tape which can be kept for long periods of time without substantial deterioration.
A further object of my invention is to provide a means for recording light impulses, sound waves, or other mechanical vibrations by producing visual indices on 'a tape which can be immediately used for analyzing the various frequency characteristics of the vibrations.
` driving the constant speed roller 9 through a Other objects of my inventionlwill be apparent from the following disclosures:
Figure 1 is an assembled View. of a combined recording and reproducing mechanism;
Fig. 2 is a schematic diagram of an amplifier; 5
Fig. 3 is a view, partly in section, taken on line 3--3 of Fig.. l;
Fig. 4 is an elevation of a modified form of recording mechanism;
Fig. 5 is a view, partly in section, taken on line m 5 5 of Fig. 4; i
Fig. 6 is a view of another form of recording mechanism;
Fig. 7 is a side view of the recording arm of Fig. 6;
Fig. 8 is an end view of the recording arm of Fig. 6;
Fig. 9 is a diagram of a battery-operated recording apparatus;
. Fig. 10 is an enlarged view of the recording arm shown in Fig. 1;
Fig. 11 is a section on line II--I I, Fig. 10; and
Fig. 12 shows a fragment of a tape partly used.
A suitable frame I is shown in Fig. 1 on which is'supported a supply reel 2 and a receiving reel 3. A vtape 4, for receiving marks or indices, carrying a suitable chemical compound (as more fully explained hereafter) is fed from the supply reel 2 between a xed contact 5 and a movable contact 6 of a recording mechanism A, and then, if it is desired to immediately reproduce the recorded signals, is lead over an exposure guide I -of the reproducing mechanism C. The tape then passes between the rollers 8 and 9 to the receiving reel 3. t 1 l f A motor I0 is provided to furnish power and operate preferably through any suitable variable speed gear reduction II todrive the shaft I2 on which is mounted a. pulley I3. Suitable belts I4 and I5 are driven from a portion of the pulley I3 and pass over pulleys I6 and I1 connected to the shafts I8 and I9 which carry the reels 2 and 3 respectively, the shafts I6 and I1 being suitably supported in the frame. The crossed driving belt 20 receives power from pulley I3 for suitable pulley connection. The motor III is pref.- erably an electric motor of theconstant speed type but may be any suitable driving. mechanism.
In order that the tape 4 may be passed at constant speed through the apparatus for recording or reproducing, the tape is driven by the constant speed roller 9` and the companion roller 8 resiliently mounted to press against the tape. The belt I4 operating between the pulley I3 and the receiving reel 3 is so mounted on the pulleys I3 and I6 that it can slip and only revolves the reel 3 at a suicient rate of speed to keep a suitable tension on the tapeas it comes from the constant speed rollers 8 and 9. The tension on the tape from the constant speed rollers revolves reel 2 and unwinds the tape from the reel, but in order to keep a suitable tension on the tape any suitable retarding mechanism may be provided, and in the mechanism shown the belt I5 is mounted between pulleys I3 and I1 so that p it tends to drive the reel in the opposite direction, but is sufliciently loosely mounted to slip on the pulleys and act as a brake to keep the desired tension on the tape. When the tension of the constant speed rollers is released from the tape, however, the belt I5, which is provided with more tension than the belt I4, will act as a driving belt for rewinding the tapeon the supply reel 2, and in this case the belt I4 acts to retard the reel 3 to preserve the desired tension on the tape.
The constant'speed pulley 8 is carried at one end of the arm 2|, which is rotatably supported on a shaft 22 at the other end. Shaft 22 is mounted on frame I, and a screw tensioning device 23 is also mounted on the frame for adjusting the arm 2| to secure the desired pressure between the rollers 8 and 9 for driving the tape.
In the recording mechanism the fixed contact 5 is mounted on an insulating panel 25, and is preferably of brass but may be of any good electrically conducting material, and is preferably provided with a curved, polished surface 26 to facilitate the passage of the tape thereover and to provide a convex surface.
A movable contact holding arm 21 is mounted for pivotal movement on the pivot member 23 carried by the insulating panel 25. on the arm 21 is a balance weight 29 which may be adjusted along the threaded portion 36 lof the contact arm. Carried by the arm 2 is a collar 3l preferably of insulating'material. To one side of the collar,`spring 32 is connected, the other end of the spring being carried by adjusting screw 33 which passes through an aperture on the threaded stud 34 and is adjustable by means of a threaded nut 34a which bears against the stud 34. The stud 34 is mounted to the panel 25. A yoke 35 is also carried by the collar 3|, the yoke being provided so that the tape 4 may pass between the sides thereof without contacting therewith. A stud 36 is similarly carried by the panel 25 through an aperture in which the screw 31 is passed, the screw being connected to the yoke 35 by means of a tension spring 38. A nut 39 engages the threaded endA of the screw 31 and bears against the stud 36 so that the screw may be adjusted.
A contact holder 40 is pivotally secured to the free end of the arm 21 by means of a screw 4I passing through the members 42 of the contacty holder and arm 21. At the outer end of the contact holder 40 a. slot 52 is provided to receive a contact blade 6. Secured to the holder 40 is a cap portion 43 in which a set screw 44 is threaded so that the set screw may be adjusted to clamp the blade 6 tightly in the holder.
An amplifier 45, which may be of the type shown in Fig. 2, is provided with suitable terminals 46 and 41. From the terminal 46 a lead 56 electrically connects terminal 46 to the fixed contact 5. The lead 5I connects the terminal 41 through the arm 21 to the movable contact 6.
The contact 6 is preferably a. thin. stift blade Mounted of any good electrical conducting material, such as a platinum alloy, steel, phosphor bronze or the like. It should be of such material that it will resist the wear due to the frictional engagement of the tape and which will stand up under the action of electrical current, and not be readily attacked by the chemical compounds carried by the tape.
For recording frequencies within the audible range the blade 6 should be as thin as practicable and still be sufliciently rigid to resist deformations due to the forces acting thereon by the passing of the tape, and the pressure between it and the xed contact 5. Steel blades as thin as one and one-half mills have been successfully used. As the blade wears it may be adjusted in the slot 52 and reset by the set screw 44 to be rigidly held in the contact holder` The width of the bladel may vary within wide limits dependent upon the current density used, the resistance of the tape and the width of record desired for reproduction purposes. A blade of one-eighth inch width has given good results with the above described apparatus.
The moment of inertia of the arm 21 about the pivot 28 is adjustable to obtain the desired engagement with the tape so that excessive vibration of the contact 6 is prevented. The tension on the springs is also adjustable to cooperate with the moment of inertia as determined by the weight and at the same time regulate Ithe pressure of the contact 6 upon the tape 4 and give the arm 521 a natural period most suitable for recording the impressed signals.
If it is not desired to reproduce the recordings immediately after the recording is made by means or the recording mechanism, the tape 4 may be passed directly to the constant speed . contact rollers 6 and 9 or over any suitable intermediate roller or guide between the recording mechanism and the constant speed rollers 8 and 9.
In the construction shown in Fig. 1, however, the tape is shown as passing through a reproducing mechanism C about to be described.
The reproducing mechanism shown in Fig. 1 consists of a concentrated lament lamp 55 and lens system 56 of the type used in sound film reproductionjor producing a narrow slot image. The lamp and lens system is used in my apparatus for concentrating the light on the tape 4 as it passes over the Vexposure guide 1 through a slotted aperture 51 in the wall of the compartment.
The light is reflected from the tape 4 into a suitable light sensitive device such for example as a photo-electric cell 58, the resistance of which is thereby caused to vary in response to the variations in intensity of the'reected light, due to indices or markings recorded upon the tape 4. The Variations in resistance are translated into voltage variations and amplied in the usual manner 'by a suitable amplifier indicated at 59. The lamp 55 is supplied with current in any suitable manner such as by the battery 55a or by a transformer and lter or rectier. The lamp 55 and lens system 56 and the photo-electric cell are preferably enclosed in suitable compartments so that unwanted light does not reach the tape 4 orthe photo-electric cell. l Y
While I have shown a well known type of slot image lens system for projecting a band of light on the tape 4, it is to be understood that any means of projecting a concentrated band of light on the tape 4 may be used, such as a plate having a narrow aperture through which the light passes, and placed directly in front of the tape, and between it and the light source and a light sensitive device responsive to variations in intensity of light, such as a suitable photo cell. In either case the light projected on the tape preferably should be a band at least as narrow as the finest width of the finest division recorded on the tape 4 in order to secure faithful reproduction of the highest frequency recorded.
The frequencies which can be reproduced depend upon the speed of the tape, the clearness of the definition and width of the recorded indices,
' leads 62 and 63 and flexible connections 64 and 65 to the recording amplifier output. The flexible connections slidingly engage the rollers. The roller 6| is mounted for rotation on the fixed pivot 66 which is mounted on `an insulating frame 61. The roller 88 is mounted for rotation on the contact arm 68 which is rotatably mounted on the pivot 69, which is similarly mounted on the insulating frame 61. Adjustable mechanism is provided for swinging the arm about the pivot 69 to move it toward or away from the tape 4 to adjust the pressure of the rollers upon the tape. The mechanism for making this adjustment comprises a screw 18 which passes through the threaded aperture in the stud 1| carried by the frame. The screw 10 is provided with a collar 12 so that the compression spring 13 is held between the screw and the arm -68 to maintain a yielding pressure, whereby irregularities in the tape 4 can be compensated for. The arm 68 has a cut out portion to engage spring 13. In order to move the roller 68 away from tape 4 a tension spring 15 is carriedY between arm 68 and stud 16.
In this construction Wear on the contacts isl largely eliminated due to the fact that the tape passes between rollers and causes the rollers to rotate,and sliding friction between the rollers is thereby eliminated.
The rollers are of small diameter and presentv substantially a line contact to the tape 4 so that the fine markings due to rapidly varying electrical impulses may b`e recorded on the` tape.
Figs. 6, '1 and 8 show still another modified form of recording mechanism. In this form the tape 4passes over a fixed contact 80. The contact member 8l is attached to a movable arm 82 which' is adapted to be raised and lowered by the action of the moving member 83 of a phonograph pickup or recorder 84 which is adjustably secured to the lever arm 85 by screw 86 engaging with the back of the recorder housing. A tension spring 81 is attached to lever 85 at one en d and to a securing means 88 at the other end. An adjusting screw 89 working through stud 98 carries a conn ector 9| which is fastened to lever arm 85 and engages screw `89. An adjusting 'nut 92 is provided to hold the screw in adj usted position.
The spring 81 and the screw 89 provide a means for accurately positioning the arm 85 so that the movable contact member 8| is held inthe desiredposition with reference to the tape 4. The lever arm 85 is rotatively connected to insulating panel 93 by shaft 94. Fixed contact 88, stud 98,
and spring holder 88 are also mounted to this insulating panel. i Thecurrent from a recording amplifier' is lead into the actuating winding of the phonographA recorder or pick-up through the terminal leads 95 and 96.
One terminal of a source of direct current potential, such as a battery or generator, is connected to lead 91 and connected to arm 82 through a very flexible lead' 98.Y The other terminal of such source is connected to fixed contact 8 8 through lead 99. The fixed contact 88 is insulated from the rest of the circuit and is similar in forml and function to the contact 5, Fig. l. AThe contact member 8| is secured to the arm 82l and is preferably thin for sharply defining the marks or cially suitable for recording the ordinary code signals, or any signal not requiring exceedingly fine graduations of frequency or tone.
While I have shown, for convenience, the mounting of considerable of the various recording mechanisms disclosed in this application on an insulating panel, itis to be understood that they may be suitably mounted on a supporting frame and electrically insulated therefrom in any suitable manner.
Fig. 2 shows diagrammatically an electrical system adapted for recording or reproducing in connection with my invention. A microphone amplifier as illustrated has a pick-up means for use when recording sound waves. In the direct' coupled amplifier illustrated VT| is a. three element thermionic valve` of the heater type cornmonly having an amplification factor .'1 to l0. VT2 is a four element thermionic valve of the heater type having a screened plate. VT3 is an output thermionic valve of large capacity. The grid |85 of VI2 is directly connected to the plate |06 of VTI and the grid |81 of VTS is directly connected to the plate |85a ofV-'I2. The plate |88 of VI3 isA connected through the milliammeter |89 to the terminal 48.
The circuit shown in this figure is that of a direct connected amplifier differing from others of this type mainly in the values of the resistance and capacities used, which values are given below by way of example. ance having a value of 25,000 ohms. Variable resistance I2, inseries with resistance I I3, has a maximum value of about 500,000 ohms. ||3 is a fixed resistance of 500,000 ohms and is connected at one end to resistance ||2 and at the other end between resistances ||1 and ||8. ||4 is a grid biasing resistance for the valve'v VT2 and has a value of 25,000 ohms. ||5 is a. potentiometer having a resistance of about 400 ohms. ||6 is a resistance of 5,000 ohms and resistance ||1has a value of 15,800 ohms. Resistance I8 has a value of 10,000 ohms and resistance ||9 has a value of about 250,000 ohms,and may be variable. Condensers |28 and |2| have a value of about a half a micro-farad each. Condensers |22 and |23 are filter condensers, and have values of one microis a grid biasing resistfarad and two micro-farad capacity, respectively.
sistances and condensers are those which I have found to give good results and these values may be departed from ,without affecting the spirit of the invention. A power transformer |21 has a primary winding adapted to the voltage and frequency of the circuit from which it is desired to draw power. The transformer |21 is also provided with three low tension windings lighting the filaments of the various valves employed in the amplifier and the high tension winding for use in conjunction with the rectifier valve |28 to provide high tension direct current for the various valves employed in the amplifier. The rectifier valve |28 is a full wave rectifier which is used as a half wave rectifier by having its plates connected as shown in Fig. 2 for the purpose of obtaining an increased output. The choke |29 should have a value of about 30 henries inductances. Terminal |30 is provided so that if desired, a loud speaker for direct monitoring purposes may be connected between the terminal |38 and the terminal 46.
The points |3|. |3|, ISI indicated as grounded in Fig. 2 are connected to each other and this may be conveniently accomplished by connecting lthem to the metal frame or a suitable ground.
In Fig. 9 is shown, diagrammaticailyy another system for supplying the varying electrical impulses to the recording contacts MD, SM between which the tape 4 passes. These contacts are simlar to those heretofore described.
In this form the signal to be recorded is supplied to the tube VT4, through audio amplifying ltransformer |42. The current passes from the battery |43, through the filament of the tube VT4, and is regulated in amount by the resistance |44. The battery |45 furnishes a suitable negative potential to the control member of the tube VT4 through the secondary Ywinding of the audio frequency transformer M2. The potential of the control member relative to the lament can be adjusted by potentiometer Ia. The battery |46 supplies the plate current to the tube VT4 through the contact members |40 and itl, through the miliammeter' |41 to the plate of the tube VT4.
follows:
Incoming signals are impressed upon the control member of the tube VT4 by means of the audio frequency transformer or other means whereby the current in the plate circuit is caused to vary in accordance with these signals. The variations in-the current passing through the tape at the contacts I G and |4| cause marks or indices of different intensities to be formed upon the tape by the action of the current, proportional in intensity and frequency to the impressedA signals.
The simplified form shown in Fig. 9 is especially convenient` for recording telegraph messages, wherein the familiar dot and dash system is used.
For recording purposes a record receiving element is desired which is ccmposed of a material which will carry chemicals reactive to the passage of electric current, and on which indices can be progressively recorded. A convenient form for such an element is that of a band or tape.
It is desirable for the band or tape to have a smooth surface so that the movable electrode may readily maintain substantially uniform relation thereto. As an example cf such material, I have found lthat a. rag paper having a smooth calendered surface, cr a sulphite paper not heavily lled or glazed, may be used.
The operation of this device is as of a particular voice.
' than for voice.
The tape is treated or impregnated, preferably with a. chemical solution which will react, upon the passage of an electric current between suitable 'contact electrodes, to produce a sexies of marks or indices, such as dots or lines, corresponding to the frequency and intensity of the electric current impressed on the tape. A fragment of tape 4 with such marks or indices thereon is shown in Fig. 12.
Preferably, it is desired to use such a chemical solution as will give a series of colored lines or dots, so that these lines or dots may be readily reproduced by means of a photo cell, or in any other manner.
I have found that a suitable bath for treating the tape may be made with 100 parts of water, parts of potassium ferro cyanide and 1 part of potassium cyanide.
Theftape may be pressed to remove the excessive moisture, or dried, or otherwise conditioned. It is more convenient for use and for handling to have in the tape'only a low moisture content. I have found that the moisture content of the tape may vary over wide limits, from the almost normal content of paper of about 10% to a nearly saturated condition. However, as stated above, for practical purposes the low moisture content is more desirable.
The use of potassium ferro cyanide and potassium cyanide in the impregnating bath gives a tape upon which a clear, colored series of indices, such as dots or lines, may be formed by subjecting the tape to a varying electric current. The potassium cyanide seems to be of benefit in the solution, in that the dots or lines appear to be more sharp and defined when this is used, and this may be because the potassium cyanide acts as a solvent for minute portions of the decomposition product at the edges of the dots or lines formed by the' action of the electric current on or roll and, as shown in Fig. 1, fed from the reel i 2` over the xed contact 5 and under the movable contact 6. The speed .of feeding the tape is prefv For example, I have found that in recording 'v voice signals I can use speeds as low as 41/2 (inches) per second, but it is usually preferable, for the best results, to use somewhat' higher speeds to bring out the peculiar characteristics For recording music, the speeds should preferably be somewhat higher I have produced satisfactory music recordings with speeds no higher than 12 inches to 14 inches perrsecond.
Itis to be noted, however, that the optimum speed of recording is dependent, not only upon the speed and intensity of the current, and the reaction speed of the chemicals used to treat the tape, but also upon the quality of the results which it is desired to obtain.
Also, it may be noted that heat' is liberated at the contact point when recording, and it may be that this liberation of heat facilitatesthe recording. The heating may be regulated by varyingthe signal intensity, the amplier controls or the output impedance of the amplifier or by other well known means.
In operation, the position of the weight 29 (Fig. 1) on the recording arm 21 and the tension of the springs 32 and 38 are adjusted to give the arm 21 a natural period, which will tend to cause the contact 6 to follow smoothly any minute irregularities in the surface of the tape and prevent the arm from following an external impulse and responding to forced vibrations. An electric current ows from the rectifier |28 through the choke |29 (Fig. 2) to terminal 41(Figs. 1 and-2) i rectifier |28.
When no signal is acting on the. apparatus, the grid of VTI is suiciently negative with respect to the cathode so that the current flowing in the plate circuit is small. The drop through resistances H2 and ||3 is, therefore, small, and grid |05 of VT2 is sufficiently positive so that a larger than normal current flows through the plate` |05e. 'I'he drop through resistance ||9 is, therefore, larger than normal, and the grid |01 of VT3 is more negative than normal with respect to the filament |34 and current owingto the plate |08, the milliamrneter |09, terminal 46, and the moving contact and tape, is small. If the grid of VTI is made more positive by an incoming signal, or otherwise, the current in the plate circuit of VTI willincrease, the current in the plate circuit of VT2 will decrease, and the current through the plate circuit of VT3 and the treated tape will increase, causing a line on the tape, the width of which is proportional to the time of duration of the signal or positive condition of the grid of VTI, and the intensity of which is proportional to the intensity of the current through the tape. Thus, a rapidly varying electro-motive force, such as that resulting from a succession of sound waves applied to the microphone '|35 (Fig. 2), results in producing a series of fine indices or marks, such as lines, on the tape, the nature or character and frequency of which correspond to the volume and frequency of the succession of sound waves which are being recorded.
The signals impressed upon thegrid |01 of the vacuumrw tube VT3 are of 4suflicient intensity to swing the gridpotential to a positive value,
causing marked variations in the plate current of the tube. The milliammeter |09 indicates these variations and furnishes a criterion of the character of the record being made upon the tape. It sometimes happens that the tape has what might be termed a.v threshold value of current, so that a current of sufficient intensity must be applied to the tape before any record is made. The normal direct current Vcomponent of the plate current of the valve VT3 is usually sulcient for this purpose, but in case a larger direct current component is required, the plate current of the valve VT3 may be increased by connecting a resistance, as |32, between the center tap of the filament transformer for VT3 and the groun side |3| of the high tension winding.
Although I have shown in Fig. 2 a. direct con.-
nected amplifier operated from an alternating current source, it is to be understood that this invention is not limited to the type of amplifier shown, for example, a transformer coupled amplifier or a resistance capacity coupled amplifier operated either from dry batteries, accumulators, or by proper rectifying means from an alternating current source may be employed.
In order to disclose the working of my invention I have shown an ordinary carbon microphone transmitter |35 connected, by means of its transformer and battery |36, to terminals |31 and |38 of the amplifier shown in Fig. 2. It is to be understood, however, that a radio receiving set or other devices for transforming light waves, sound waves or'other mechanical vibrations into electrical energy may be utilized in place of the transmitter microphone.
It will be seen that I have shown a. mechanism making it possible to record on a. tape and then immediately reproduce the record for monitoring or other purposes. It will also be seen that the reproducing apparatus can be operated without a recording mechanism to reproduce recordings that have already been made, since the recordings on the tape are of such a nature that the tape can be keptfor long periods of time before being reproduced without deterioration of the record.
Furthermore, my invention furnishes a method of introducing a delay between the production of speech or music and the reproduction of the same. For instance, if -it be desired to reproduce the speech or music shortly after its production, and
the length of tape between the recording mechanism and the reproducing mechanism is 14 inches and the tape is running at the rate of 14 inches per second, a delay of one second between the recording and the reproduction of the sound will occur. This delay will occur while the tape is traveling from the recording point to the reproducing point. This time obviously may be varied by changing the distance between the recording and reproducing points to obtain. the desired amount of delay. f
There are many interesting and useful applications o1 this: .for instance, such as when a person desired to play a phrase of music, or speak va few sentences, and have that phrase or speech reproduced as soon as he-is through playing or speaking, in order that he may obtain an idea of how it sounds and what the resultant effect is; or when a delay is desired as in two-waywireless communication, to allow time for cutting oli" the transmitter and cutting in the receiver without apparent interruption in the communication.
Afurther advantage of this device lies in its ability to render signals or messages unintelligible in transmission. This may be accomplished either by running the tape with indices recorded thereon, backward through the reproducing devicey for transmission, receiving and recording on another tape, and running that tape backward through a reproducing device for intelligible reception of the signals as messages, or by running the tape through the reproducing device and transmitter at a rate' of speed sufliciently high to prevent intelligible reception and then receiving and recording at a rate of speed corresponding tothe transmitting speedgand reproducing the message by running the tape at a lower rate of speed.
It will be noted that an important advantage to be substantially dry, and can, therefore, be readily handled in' reeling and storing, and held in this condition Without the necessity of meistening the tape immediately before recording.
It will also be seen that after the recording is made the moisture content is substantially immaterial, an'd that the tape may be wound on reels, rolls, or the like, and stored for long periods of time until it is desired to use it for'reproduction.
Also, it will be seen that a relatively narrow tape, such as one-half inch, may be used, and 1 that a large amount of recording Will be relatively light and may be easilystored and transported. It may be noted, however, that a tape sufficiently wide to have impressed thereon a plurality of series of indices by passing the tape successive times through the recording mechanism may be used. l
It will also be seen that, instead of treating or coating a tape with chemical compounds to enable it to receive the marks or indices, such compounds may be incorporated in the paper or other material from which the tape is made during the manufacture ofthe tape.
Furthermore, it 'is to be understood that the particular forms of apparatus shown and de scribed, and the particular procedure set forth, are presented for purposes of explanation and illustration and that various modifications of said apparatus and procedure can be made without departing from my invention as defined in the appended claims.
What I claim is:
1. Apparatus for recording electrical impulses, which comprises, in combination, a movable tape carrying a substance adapted to react to the passage of an electric current therethrough, a thermionic valve or valves, means for applying varying voltages to the thermionic valve or valves, means coacting with the movable tape forimpressing the resultant varying electrical output of the thermionic valve or valves thereon, said means comprising electrodes, one of which is a thin blade disposed transversely of the tape, and means for moving said tape, whereby successive lines are produced on the tape transversely thereof, each line being produced by a single electrical pulsation.
2. Apparatus for recording and reproducing` Soundwaves in the audible range which comprises, in combination, a movable tape carrying a substance adapted to react to the action of an electric current, a thermionic valve, means for receiving sound waves and transforming them into electrical impulses and for subjecting the control member of said thermionic value to sai-d impulses, means for moving the tape, means for 'impressing the electrical output of said valve on successive portions of the tape to form a series ci indices, means .for impinging a light beam upon indices of the moving tape and reflecting the light into a light sensitive device of a type. ca` pable of transformng light variations to electrical impulses, and means for transforming these elecvariations into electrical impulses, and means for transforming these electrical impulses into high frequency sound waves, whereby vocal and musi- I cal sounds may be accurately recorded and reproduced.
4. Apparatus for recording and reproducing sound Waves in the high frequency audible range, l
which comprises in combination,'a movable tape carrying a substance adapted to react to the effect of electric current thereon, a thermionic valve, means for receiving such sound waves and transforming them into electrical impulses, means for applying said electrical impulses to the thermionic valve, electrodes disposed transversely of the'tape on opposite sides of the tape connected to receive the resultant varying electrical output of the thermionic valve, means for moving said tape between said electrodes whereby indices are iii produced on successive portions of the tape, one of said electrodes comprising a thin recording blade disposed transversely of the tape to produce indices of relatively fine gradations corresponding to the basic frequencies and harmonics of the i vocal and musical sounds being recorded and reproduced, means for impinging light beams upon said indices of the moving tape and reecting the light into a light-sensitive device of the type capable of transforming light variations into elecl trical impulses, and means for transforming these electrical impulses into high frequency sound waves whereby vocal and musical sounds may be accurately recorded and reproduced.
5. Apparatus for recording and reproducing sound waves in the audible range which comprises, in combination,v a movable tape carrying a substance adapted to react to the action of an electric current, a thermionic valve, means for receiving sound waves and'transforming them a into electrical impulses and for subjecting the control member of said thermionic valve to said impulses, means for moving the, tape and means for impressing the electrical output of said valve on successive portions of the tape in the form of transverse lines of materially greater length than Width, and means controlled 'by said tape for producing electrical impulses corresponding to those impressed on the tape and for transforming these electrical impulses into sound waves corresponding to those producing the electrical impulses previously impressed on the tape.
6. A method of recording electricalimpulses upon a tape carrying a substance adapted to react to the effect of electric current thereon, which consists in applying varying volt-ages to a thermionic valve or valves, impressing the resultant varying electrical output of said valve or valves on successive portions of said tape to form ne transverse lines proportional in spacing and intensity to the variation of the current in frequency and intensity while moving the tape at a substantially uniform speed and thereby causing successive portions of the moving tape to receive the eiiect of the electrical impulses impressed thereon and to be differentiated from other portions of the tape.
7. A method of recording electrical impulses on a tape 'carrying a substance adapted to react to the effect of electric current thereon, which consists in applying varyng voltages to a thermionic valve or valves, feeding the tape at a substantially uniform speed in proper relation to electrical contacts to receive electrical impulses therefrom, impressing the resultant varying electrical output of said valve or valves on said tape to form successive fine transverse lines of materially greater length than width and proportional in spacing and intensity to the varying electrical output of said valve or valves while the tape is moving relative to the contacts, and thereby causing portions of the moving tape to receive the effect of the electrical impulses impressed thereon and to be differentiated from other portions of the tape.
8. A method of reproducing mechanical vibrations, which consists in transforming-said vibrations into electrical impulses, applying the electrical impulses to a thermicnc valve, impressing the resultant varying electrical output of said valve on portions of a tape, carrying a substance adapted to react to the effect of electric current thereon, to cause successive indices to be produced on said tape, causing a light beam to im` pinge upon said indices on the moving tape and to be reflected into a light sensitive device of a type capable of transforming light variations into electrical impulses, and transforming these electrical impulses into mechanical vibrations ofk substantially the same frequency and intensity as those originally transformed into electrical impulses. Y
9. A method of reproducing mechanical vibrations, which consists in transforming said vibrations into electrical impulses, applying the electrical impulses to a thermionic valve, moving at a uniform rate a tape carrying a substance adapted to react to the effect of electric current, impressing the resultant varying electrical output of said valve on portions of said tape, to cause successive transverse lines to be produced on said tape, causing a light beam to impinge upon said lines on the moving tape and to be reflected into a photo cell, and transforming the vresulting electrical vibrations of said cell into mechanical vibrations.
10. A method of reproducing mechanical vibrations, which consists in transforming said vibrations into electrical impulses, applying the electrical impulses to a thermionic valve, moving at a uniform rate a tape carrying a substance adapted to react to the effect of electric current, impressing the resultant varying electrical output of said valve on portions of said tape, to cause l successive indices to be produced on said tapeg` and reproducing from said indices the recorded signal after a predetermined lapse-of time.
11. A method of reproducing sound vibrations,
which consists in transforming sound vibrations into electrical impulses, impressing the electrical impulses on a moving tape carrying a substance ting mechanical vibrations, such as code signals or sound waves, and maintaining them secret durspeed, and transmitting the electrical impulses so produced to a second recording apparatus similar to the first and having a tape moving at a relatively high rate of i speed corresponding to that of the first tape and reproducing the mechanical vibrations from the second tape at a speed corresponding to the original recording speed.
13. Apparatus for recording and reproducing electrical impulses which comprises, in combinatio/n, a movable tape carrying a substance to react to the action of an electrical current thereon, a pair of rollers disposed on opposite -sides of the tape and con cted to receive the electrical impulses, means for o'ving the tape between said rollers whereby transverse lines of greater length than width are producedon successive portions of the tape, means for impinging a beam of light upon said lines of said moving tape and causing the light coming from said tape to pass into a light sensitive device of the type capable of transforming light variations into electrical'impulses.
14. Apparatus for recording sound waves which comprises, in combination, a movable tape carrying a substance adapted to react to the effect of electric current thereon, a thermionic valve,
means for receiving such sound waves and transforming them into electrical impulses, means for applying the electrical impulses to the thermionic valve, electrodes disposed on oppositel sides of the tape, and connected to receive the resultant varying electrical output of the thermionic valve, one Vt:
of the electrodes including a .thin blade mounted transversely of the tape, said electrode being mounted for yielding movement relative to the tape so that the electrode `may have a natural period most suitable for recording the impressed signals, whereby transverse indices of relatively fine gradations corresponding to the basic frequencies and harmonics of the sounds being recorded are produced on the tape.
15. The method of recording and reproducing a varying electric current, which consists in impregnating an opaque record member with a chemical which changes its color on the passage of electricity therethrough, passing said current through an amplifying system whereby the variations in said current are sensibly amplified, passing said opaque record between electrodes connected to said amplifier whereby said amplified r current is passed through said record and discolors it along afpredetermined course in a manner corresponding to the variations in said current, impinging a constant beam of light on said opaque record along said predetermined course, causing reflected lightfrom said record along said predetermined course to pass into a photo cell, and amplifying the electric output of said photo cell, whereby a varying electric current whose variations correspond in frequency and intensity with the original electric current is obtained. i
16. Apparatus for recording electrical impulses which comprises, in combination, a tape carrying a substance adapted to react to the action of an electric current, said tape having such a relatively low moisture content that it appears dry, a thermionic valve, means for moving the tape,
means for impressing the output of the valve on successive portions of the tape to form transverse lines of materially greater length than width on said tape, said lines varying in spacing and intensity irl-proportion to the impulses impressed upon the valve.
17. A tape of the character on which sharply contrasting lines, varying in spacing and intensity, may be produced under the influence of a rapidly varying electric current, which comprises a paper tape impregnated with a solution of a chemical capable of change of color upon the passage of an electric current through the chemical, the moisture content of the tape being such that the tape appears dry but contains more than 10% moisture.
18. Apparatus for recording and reproducing sound waves in the audible range, which comprises, in combination, a movable tape carrying a substance adapted to change in color from the eiect of electric current thereon, means for receiving such sound waves and transforming them into electrical impulses, an electrical amplifying system including one or more thermionic valves, means for applying said electrical impulses -to the amplifying system, electrodes disposed transversely of the tape on opposite sides thereof connected to receive the resultant varying electrical output of the amplifying system, means for moving said tape between said electrodes whereby discolorations are produced on successive portions of the tape transversely thereof of materially greater length than width and varying in frequency and intensity with the variations in frequency and intensity of the original sound, means for impinging a light beam upon said indices'of the moving tape, and means for passing the resultant varying reflectedlight into a light sensitive device of the type capable of transforming light variations into electrical impulses, and means for transforming these electrical impulses into sound Waves, whereby vocal and musical sounds may be accurately recorded and reproduced.
19. Apparatus for recording electrical impulses comprising in combination, a tape carrying a substance adapted to react to the passage of electrical current therethrough, means for moving said tape, a plurality of thermionic valves directly coupled in cascade, a source of high tension direct current, the majority of which current must pass through said tape and last of said thermionic valves in cascade to the other valves directly coupled to said last valv`emeans for impressing varying electrical impulses on the control member of the first of said thermionic valves in cascade, whereby successive indices in the form of distinct transverse lines are formed on said tape which correspond in spacing and intensity proportionally to the frequency and intensity of the impressed electrical impulses.
' consists in applying varying electrical impulses to a thermionic Valve, applying the output of the valve to an electro-magnetic member capable of vibrating in response to varying electrical impulses and having a thin recording blade electrode, feeding 'thetape at a substantially uniform speed over a stationary electrode spaced from the first electrode, and applying direct current across said electrodes and through the tape disposed therebetween, whereby the eect of the electrical impulses impressed upon the valve are impressed on the tape in the form of transverse lines of greater length than Width.
2l. An opaque paper tape impregnated with a chemical and having indices impressed thereon as the result of the direct application to said tape of electrical impulses, said indices comprising visual, successive, transverse lines relatively narrow in width and of materially greater length than Width, and also being proportional in spacing and intensity to said electrical impulses.
MERLE DUsToN.
US556743A 1931-08-13 1931-08-13 Method of and apparatus for electrically recording and reproducing sound or other vibrations Expired - Lifetime US2030973A (en)

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