US1827735A - Volume control in sound record reproduction - Google Patents

Description

Oct. 20, 1931. J. R. BALSLEY V VOLUME CONTROL IN SOUND RECORD REPRODUCTION 1929 4 Sheets-Sheet Fi ed Oct. 14,

Inventor Jamsflflalsley,

flttorncy Oct. 20, 1931. J. R. BALSLEY VOLUME CONTROL IN SOUND RECORD REPRODUCTION Filed Oct. 14, 1929 4 Sheets-Sheet 2 Jrzuvzior James 15'. Balsley.

flttorlzey.

Oct. 20, 1931. J. R. BA'LSLEY 1,827,735

VOLUME CONTROL IN SOUND RECORD REPRODUCTION Filed Oct. 14, 1929 4 Sheets-Sheet 3 c 109 I n I II I I l 4 I I I E E a 1722012102 James REaZJl ey,

Oct. 20, 1931.

VOLUME J. R. BALSLEY 1,827,735

CONTROL IN SOUND RECORD REPRODUCTION Filed Oct. 14, 1929 4 Sheets-Sheet 4 I m/enZor Jarrwskflalslqy.

Patented Oct. 20, 1931 UNITED STATES PATENT, OFFICE JAMES a. rust, or BEVERLY 'rrrLLs, camromwm, assrenoa 'ro rox mu con.-

roaa'rron, or nonmrwoon, cmronm, a comom'rrox or m You 'VOIlIJ'ME CONTROL IN SOUND RECORD BIEPBODUUIION Application filed October 14, 1928. Serial No. 898,464.

' I i This invention relates generally to the reproduction ofsound from sound records, and is -more particularly concerned with means for controlling the volume of sound reproduced from sound records. The invens tion is particularly applicable to systems in which the photographic type of sound records are utilized, and will therefore be hereinafter described with that type of sound record chiefly in View; but it will readily be understood that this particulariza-tion constitutes no limitation on the invention, for the invention may also be practiced in connection with other types of sound records such as the mechanical disk type.

In sound reproduction from photographic sound records of the varying width type, the volume of the reproduced sound is proportional ,to the amplitude of the serrations along the record. The volume ran e of the reproduced sound is limited on t e lower side by ground noise, and on the upper side by the physical characteristics of the film and the electrical and mechanical limitations of the system. In reproduction from photographic records of the varyin density type,

the volume of the reproduce sound is pro-- portional to the change in transmission of the sound record. In the latter system the practical volume range is limited for undistorted quality by the length of the straight line portion of the light-transmission characteristic of the film,and is further limited on on the lower side by the ground noise level of the film, and on the upper side by the physical characteristics of the film, plus the electrical and mechanical limitations of the recording and reproducing units.

Corresponding factors similarily limit the practical available volume range in sound reproduction systems utilizing other types of sound records. I

It is a primary object of the present invention to provide means for expanding the pracprovide means whereby the volume of sound in final audible reproduction from a sound record may be controlled at predetermined levels, irrespective of the levels at which the sound wasoriginally recorded.

According to the present invention, these obg'ects are accom lished by the provision of a volume-control record driven in synchronism with" the sound record, and adapted to control the volume level of the sound reproduced from the sound record. In my preferred emblodimelnt this voluntiie controllr ecord m'ay simp ya varyin ensit otographic record, which may be pre lu led by reference to the volume level 'of t e sound record as recorded, as'may be determined by ordinary reproduction thereof. This volume control record, which may be printed on the same film that carries the pictures and sound record, for instance outside the sprocket perforations thereof, or on a separate film if more convenient, is o erated in conjunction with a light beam and photoelectric cell to produce a varying electrical current which is utilized tocontrol the level of reproduction, and to do this irrespective of the level at which the sound record was recorded.

With the foregoing in mind, the invention will best be understood from the following detailed description of a present preferred embodiment thereof, reference for this purpose being had to the accompanying draw- 1ngs,'in which: I

1 shows in diagrammatic form a system r producing a volume control record on the same film that carries the sound record and pictures;

Fig. 2 shows a system in which the volume record and controllin the volume thereof representing t The sound reproducing and sound controleeann fied reproduction of the original sound recnected to lead 20 between condenser C and the 0rd; 1 L grid of tube 21, this lead and the resistance R, Fi 3 shows a system for reproducin roviding for a negative bias on the grid. soun from aphotographic sound record an be output leads 27 and 28 of amplifier 22 controlling the volume level thereof inacare shown connected to ausual speaker 29. cordance with the present invention; A photographic volume control record is Fi 4 shows a system for reproducing made by reference to the volume level of the sound from a mechanical disk record an sound record 12, as hereinafter described, controlling the volume level thereof by means this volume control record eonsistin in the of a photographic volume control record; present case ofa varying density nd 30 yFig. showsa variational system for reprinted on film outsi e of the sprocket producing sound from a photographic sound perforations 13,};md its variations in density t e in accordance with t e present invention, changes deslred. A ight-slit 31 is provided and- 4 before record 30, slit 31 being illuminated, Fig. 6 shows another variatioual system forinstance, means. of an illuminant 32 for reproducing sound. from a photographic and lens 33. sound-record and controlling the volume slit 31 strike'the record on film 10, and the thereo- 3n accordance with the present invenrays transmitted therethrough, which, of course, are-proportional to the transmission of the record, impinge upon a photoelectric ling system, diagrammatically illustrated in cell 35 to generate an electrical current there- Fig. 3, will be described first, after which in inversely roportional to the density of wi 1 be explained how the volume controlling record 30. P otoelectric cell 35 is connected record .therein utilized can be prepared. by means of lead 36 and 37 directly across Referring therefore to Fig. 3 the numeral the grid and plate of vacuum tube 38. In- 10 indicates the moving sound-picture film cludedin the plate circuit 39 of tube 38 is having-thereon the usual pictures 11 and a'battery 40 and the resistance R, of lead sound record 12 between t e two rows of 26, and included in the grid circuit 41 of the sprocket perforations 13, as usual, and contube is a resistance R, and abattery 42. ventionall illustrated as driven by means The plate circuit 39 of tube 38 is so conof a sproc et 14. The re roducing elements nected with respect to resistance R, that for the sound record 12 include tygically a when tube 38 has normal plate current (no. light-slit 15 located before the soun record, light on photoelectrical cell 35), the plate curan illuminant 16, alens 17 for throwing light rent creates a dro across R, such as to oprays from illuminant lfi through slit 15 to pose the normal rop therein, and thus rethe sound record 12, and a photoelectric cell duce the bias on .the grid-of tube 21 to such a 18 positioned to be impinged by the light rays value 11%;; amplification is at a m ximumwhich are transmitted through the sound rec- When, ever, light impinges on cell 35, a old. These trans ittd light rays a m llcurrent flows in leads 36 and 37 which, when lated in Pas ing lgl' llgh he Soun recor the cell is connected in the circuit withproper redetermined volume i 4 he light-rays passing through 0n the film by t sound-wave-representing regard topolarit reduces thdkpotential of the plate, and this in turn causes the plate is shown, the balance oft density variations thereon, and, striking the photo-electric cell, generate therein a varymg electrical current corresponding to the onginal sound waves. One side of the photoelectric cell is grounded, as shown, whlle the other side is connected by means of a lead 20 to the grid of the first tube 21 of thevacuum tube amplifier, conventionall illustrated at 22. Only the first st e of t e am lifier e circuit belng of any suitable or well-known't pe. A battery 25 is connected at one side t rouglra resistance R to lead 20 and at the-other side to ground, for the purpose of providing a conv is connecte at one side to the negative ter-' minal of the filament of tube 21, and at the other side to ground. A

gcrounded lead 26 having therein resistances A, condenser O is provided inilead 20 becurrent to be reduced, which accordingly allows the drop across R, to increase. This causes an increased negative bias on the grid,- which finally means a reduction of amplification, as is well understood in the art.

It is possible to operate with the polarity of the photoelectriozcell reversed, in which case an increase in cell current operates to decrease the drop across R and hence to increase the amplification of the system. In such" a case the system is, of course, so des1 tamed when there is no lig t on the cell.

The bias onthe grid of the amplifier tube ed that minimum am lification is ob- 21,: and therefore the amplification of the Ill ofrecording or the nature of the sound record by merely preparing and utilizing the proper volume control record.

The volume control record may be made in a system such as is illustrated in Fig. 1. As there illustrated, the traveling sound-picture film 10 is intercepted in a band outside its perforations 13 by alight beam cast from an illuminated light-slit 46 by means of a lens 45, slit 46 being illuminated b an incandescent lamp 47. Lamp 47 is lig ted by means of a battery 48, a variable-potentiometer 49 being included in the lighting circuit for the purpose of varying the potential impressed upon the lamp and hence the light intensity thereof and the density of the record 30 printed on film 10. Potentiometer 49 may be regulated either manually in accordance with predetermined data or automatically in accordance with predetermined settings of suitable devices. The operation may conveniently be carried on during the printing of either the pictures or the sound record on the film 10, utilizing for this purpose devices and methods similar to those now commonly employed for varying the intensity of the printin li ht as the changing scenes require.

n ig. 2 is shown a variational sys em for making the volume control record. In this case the volume control record 30 is printed upon a film 50 separate from the film 10a which carries the pictures 11 and sound rec" ord 12. 1 In this figure there is shown a system by which the volume control record 30 can be made under manual control by an operator while listening to a reproduction of the sound record 12 at the levels of original recordin The films 10a and are conventionally illustrated as synchronously driven by sprockets 51 and 52 mounted on a driving shaft 53, shaft 53 being driven by any convenient means, not shown. The sound record12 on film 10a is reproduced as audible sound in any usual manner, for instance, by means for an illuminant 54, lens 55, slit 56, photoelectric cell 57, amplifier 58 and speaker 59. An optical system is provided for printing a varying density record on the moving film 50, and comprises typically an incandescent lamp 60, a slit 61 illuminated thereby, and a lens 62 for casting an image of slit 61 on the moving film 50. A battery 65 is connected by means of circuit 66 with lamp 60, a variable potentiometer 67 being provided in the circuit for the purpose of controlling the potential impressed on the lamp, and-hence the intensity 5 of its light and the density of the volume record 30. The operation of this system is as follows: A trained operator listens to the reproduction of record 12, and simultaneously controls the variable potentiometer 67, which governs the density of the volume control record which is being produced. Knowing from experience how the settings of potentiometer 67 govern the volume modifying characteristics of the record 30 which he is producing, the operator is able to listen to the sound reproduced by speaker 59 and simultaneousl set or control his potentiometer'67 in accor ance with the volume changes which he desires to be finally effected, in such a way that in final reproduction the volume control record which he has made will modify or control the volume of the reproduced sound at the levels whichhe has thus predetermined.

In Fig. 4 is shown a system for controlling volume level in reproduction from a sound record of the mechanical disk type. The mechanical disk record is shown at 104, and an electro-magnetic pick-up therefor at 105. One side of the pick-up is grounded, while the other side thereof is connected by lead 106 to the grid of the first tube 107 of the vacuum tube amplifier, conventionally illustrated at 108. Only the first stage of the amplifier is shown, the balance of the ampli fying circuit being of any suitable or well known type. The output leads 109 of the amplifier are connected to a speaker unit 110,

as usual. The negative terminal of the filament of amplifier tube 107 is connected ,through a resistance It to ground, and a condenser C is included in lead 106. A lead 111 having therein resistances R and R is con nected to lead 106 between condenser C and the grid of tube 107.

Themoving film 112 having thereon the volume control record 113 is passed before the photoelectric cell 35, and an optical system consisting of an illuminant 32, lens 33 and a light-slit '31 is utilized to transmit light rays throu h record 113 to impinge upon photoelectric cell 35. Cell 35 is connected across the grid and plate of a vacuum tube 38, the plate circuit 39 of which include the resistance R fand the grid circuit of which include a resistance R,. The operation of the volume controlling portion of this system is identical with that of the systems illustrated in Fig. 3, and will be understood without further explanation.

Various other schemes for controlling the volume level of reproduced sound in accordance, :with an electrical current produced from a volume control record are possible. For instance, as illustrated in Fig. 5, the property of a photoelectric cell by virtue of which its sensitivity varies in accordance with the applied potential, may be utilized to this end. The system illustrated in Fig. 5 has the film 10 with its sound record 12 and optical system therefor 15, 16, 17, and also with the volume control record 30 and optical system '31. 32, 33, all similar to the previously described system of Fig. 3. Here, however. one side of the photoelectric cell 70, provided for sound record 12, is connected by means of lead 71 to the grid of the first tube 72 of the vacuum tube amplifier, conventionally illustrated at 73. The other side of the cell is connected Ill by lead 74 to a battery 75, and the other side of the battery is connected by lead 7 6 to lead 71, lead 76 having therein resistances R, and

R and being grounded between the two re- 'sistances, as shown. The output leads 77 of the amplifier are connected to a usual speaker 78. A condenser G is located in lead 71 between the connection therewith of lead 76 Photoelectric cell 80, in which is generated an electromotive force proportional to the volume control record 30, is connected'by leads 81 and 82 with the grid and Flate/respectively of the vacuum tube 83. he plate circuit 84 of the-tube-83 includes the resistance R,,- aud the grid circuit 85 thereof in cludes a resistance R The connections of the circuit may be made to such that an increase in the hotoelectric cell current in circuit 81, 82 Wlll cause either an increase or a decrease in the drop across resistance R de pending merely upon the polarit of various connections of the circuit, as wi 1 be understood. If the system is so arranged that an increase in photoelectric cell current will cause an increased drop across resistance R,, then the constants of the system will be so balanced that with no light on photoelectric cell 80, and hence a minimum drop across resistance R,, a maximum potential will 'be impressed by battery 75 across photoelectric 85 cell 70. The sensitivity of photoelectric cell 70, and hence the volume level of reproduction, will then be at a maximum. When, however, cell 80 is impinged upon by a beam of light the drop across resistance R, is increased and the potential applied to cell '70 correspondingly decreased, to the end that the sensitivity of cell and hence the volume level of reproduction are correspondingly lowered. If, on the other hand, the conneci 45 tions are so arranged that an increase in the photoelectric cell current in circuit 81, 82 causes a decrease in the drop'across resistance R then the sensitivity of cell 70, and correspondin ly the volume level of re rol0 duction, will e at a maximum when the light impinging on cell. is at a maximum, and

a decrease in the light impinging on cell 80 will produce a decrease in the volume of reproduction, as will be understood. 1

6 In Fig. 6 is shown'a system for controlling the :amplifier' by means of a screen grid. Here again, the film 10 with its sound record 12 and optical system 15, 16,17, and also with the volume control record 30 and op- I! tical system 31, 32, 33, are similar to the system, of Fig. 3. The photoelectric cell for sound record 12 is grounded at one side, and

is connected at its other side by lead 91 to the grid of the first tube 92 of the vacuum tube I amplifier. conventionally illustrated at 93.

ground noise can be made relatively The filament of tube 92 is connected by lead 94 to und, and also to battery 95,1418 other side 0 which is connected through resistance R to the grid of the tube; A screen grid 96 provided 1n'tube"92 is connected b a lead 97 to one side ofv a battery 98 and e other side of battery 98 is connected to one side of a resistance the other side of which ia connected to ound, as indicated. Resistance lit is inc uded in the plate circuit 99 of a vacuum tube 100, across the grid and plate elements of which are connected leads 101 i from a photoelectric cell 102 provided for the volume control record 30 on film 10. The

output leads 103 of amplifier 93 are connected to a usual speaker unit 104.

The light transmitted through volume control record 30 affects the photoelectric cell 102 to generate a proportional current therein, which current acts upon the vacuum tubev circuit to vary the drop across resistance R; p

in the platecircuit 99. Variation of the drop across R, then varies the potential on the the amplification is in exact direct proportion to the potential applied to the screen grid, and the volume control therefore follows a straight line characteristic. 7

From what'has now been said, it will be recognized that'the invention in all of its described .forms provides means for greatly enlarging the practicable volume range in reproduction of sound records, whatever may be the nature or characteristics of thesound records utilized. In another aspect, it provides for the adjustment or modification of the level of reproduction of the original sound record. 4

- An advantage in the use of the present invention resides in the possibility of reducing ground noise to negligible roportions. Ground noise is only audible or o jectionable when the ratio of-recorded sound to ground noise is low. Therefore, by merely recording all sound at higher than usual levels and re ucin these levels in reproduction according to the methods of the present invention, so small as to be entirely negligible. v

The system will in many cases eliminate the necessity for retakes, which are now often required for the reason that when a picture is completed it is found that certain scenes must be rejected because they are recorded at an improper level to match up with the balance of the picture. The application of the present'invention to such a situation is obvious.

In general, the system thus provides for the correction or adjustment of volume level 'after the picture is completed. And in addition it makes reproduction possible at both higher and lower levels than have heretofore been consistent with substantially perfect or acceptable reproduction.

It will be recognized that the illustrative systems specifically described herein are capable of considerable modification and rearrangement without departing from the spirit and scopeof m invention; and it is therefore to be un erstood that the following claims embrace all such' modifications and equivalent arrangements as may fairly be construed to fall within the scope of my invention. j

I claim:

1. In combination with a system for reproducing sound waves from a sound record, which system includes means for driving the sound record, means for producing from the sound record varying electrical current waves correspondin to the sound waves, and means for reproducing sound from said current waves; a volume control record moved synchronously with the sound record, means for producing from the volume control record electrical currents corresponding to volume variations recorded thereon, a vacuum tube and a circuit therefor, leads connecting the varying electrical current produced from the volume control record across the grid and plate of said vacuum tube, whereby a varying piate current corresponding thereto appears in the plate circuit of the tube, and means for modifying the volume level of the reproduced sound in accordance with the variations in said plate current.

2. In a system for reproducing sound waves from a sound record, means for driving the sound record, means for producing from the sound record varying electrical current waves corresponding to the sound waves, a vacuum tube amplifier for amplifying said current waves, a volume control record'driven synchronously with the sound record, means for producing "from the volume control record electrical currents corresponding to volume variations recorded thereon, a vacuum tube and circuit therefor, circuiting connecting the varying electrical current produced from the volume control record across the grid and plate of said vacuum tube, where-bya varying plate current corresponding thereto appears in the plate circuit of the tube, means providing a varying grid bias on a tube of the amplifier in accordance with the variations in said plate current, and means for reproducing sound waves from the electrical current output of the amplifier.

3. In a system; for reproducing sound waves from a sound record, means for driving the sound record, means for producing from the sound record varying electrical current waves correspondmg to the sound waves, a vacuum tube amplifier or amplifying said current waves, a resistance between thefilament and grid of a tube of said amplifier providing negative bias onsaid grid, 8. volume control record driven synchronously with the sound record, means for producing from the volume control record electrical currents corresponding to volume variations recorded thereon, a vacuum tube,

a plate circuit therefor including the biasing negative bias on the amplifier tube and t erefore the amplification of the tube, and means for reproducing sound waves from the electrical current output of the amplifier.

4. In a system. for reproducin sound waves from a sound record, means or driving the sound record, means for producing from the sound record varyin electrical waves corresponding to the soun waves, circuiting including a vacuum tube amplifier for transmitting said varying electrical waves, a vacuum tube in said circuiting including filament, grid, plate and screen grid elements, a volume control record driven synchronously with the sound record, means for producing from the volume control record varying electrical currents corresponding to volume variations recorded thereon, a vacuum tube having grid and plate elements, a circuit therefor, circuiting connecting the varying electrical current produced from the volume control record across the grid and plate of the last mentioned vacuum tube, so that a correspondingly varying plate current appears in the plate circuit of the tube, circuiting connecting said plate circuit with the screen grid of the screen grid vacuum tube in such 'a. manner that said varying plate current controls the amplification of the screen grid tube, and means for reproducing sound waves from the electrical current output of the amplifier.

5. In a system for reproducing sound waves from a sound record, means for driving the sound record, means including a source of light and a photoelectric cell for producing electrical waves from the sound record, a circuit for transmitting said electrical waves, means for reproducing sound waves from said electrical waves, .a volume control record moved in synchronism with the sound record, means for producing from the volume control record electrical current waves corres onding to volume variations recorded -t ereon, a vacuum tube having grid and plate elements and a circuit therefor, circuiting connecting the varyin electrical current produced from the Y v0 ume control record across the grid and j platedof said vacuumltllbe, so that a corres n mgyvarym a e curren a pears 1n 6 t8: plate circu1t of tl ie vacuum tube and cm cui'tmg associating said plate circuit with the hotoelectric cell of the sound record reproducing means so that'the output of said N photoelectric cell is controlled in accordance I 10 with the plate current variations. c v In witness that I claim the foregoing I .have'hereunto subscribed my name t is 19th day of September 1929. :IAMES R. BALSLEY.

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