US2026398A - Twin phonograph - Google Patents

Description

Dec. 31, 1935.

L. D. NORTON ET AL TWIN PHONOGRAPH Original Filed April 14, 1932 4 Sheets-Sheet l INVENTORS Leland llivo l'on John llf/enholdf 'Dec. 31, 1935. D NORTON ET AL Y 2,026,398

TWIN PHONOGRAPH 1 Original Filed April 14, 1952 4 Sheets-Sheet 3' INVENTORS 6/ H 1 9 /I I: h

L. D. NORTON ETIAL 231126;,398;

TWIN PHONOGRAPH Oniginah E-i hedi April 14, 19325 4 sme ma-amt 4-:

BY ATTOR N EYS Wm -M render both units operative;

Patented Dec. 31 1935 TWIN PHONOGRAPH Leland n. Norton and John is. Rcnholdt, Bridgeport, Conn, assignors to Dictaphone Corporation, New Yorln N. Y., a corporation of New York Application April 14, 1932, Serial No. 605,202 Renewed June 29, 1934 21 Claim.

This invention relates to twin-phonographs for recording lengthy speeches, telephone conversations and the like; and more particularly to means for controlling the alternate operation of the units thereof.

Oneof the objects of the invention is to provide a simple and reliable control for twin-phonographs for alternating the operation of units. Another object of the invention is to provide an adjustable control for the respective electrical elements of the units of a twin-phonograph for causing alternate operation of the twin units of the phonographs in such a way as to provide an adjustable predetermined degree of re etition of the material being recorded as one fiat finishes a recording operation and the other unit starts a recording operation. A further object is to materially increase the efficiency of the active recording unit by ensuring uniformity of magnetic energization. Another object of the invention is to provide a control of the nature described for reliably de-energizing the electrical iecorder of a unit when power for driving that unit is cut ofi.

Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which are shown one of the various possible embodiments of this invention,

Fig. 1 is a vertical section of a twin-phonograph embodying the present invention, taken substantially on line l--l of Fig. 2;

Fig. 2 is a plan and section taken substantially on line 22 of Fig. 1 certain parts being broken away to show a feature, of our invention comprising circuit changing means in position to Fig. 3 is a vertical section taken on line 3-3 of Fig. 1;

Fig. 4 is an enlarged section taken on line 4-4 of Fig. 3 containing diagrams of -circuits controlled by our circuit changing mechanism;

Fig. 5 is a view showing the switches of Fig. 4 in a position to render unit A operative and unit B inoperative;

Fig. 6 is a fragmentary plan view of our switch control mechanism in' the position it wiil occupy when the unit A is recording and the i3 is inoperative and the unit B operative; and,

' un t.

inoperative, and just before the switch mechanism is actuated to set the unit B in operation;

Fig. 7 is a view similar to Fig. 6 but showing the switch mechanism shifted to render the unit A Fig. 8 is a view similar to Figs. 6 and 7 showing the condition of the switch mechanism when both units have been rendered inoperative by each respective carriage reaching the end of its recording travel. 10

Corresponding reference characters refer to corresponding parts throughout the several views ofthe drawings.

Before describing the present invention in detail, it may be well to give consideration to certain of the more general aspects of twin-phonoraph operation and control. One of the principal uses of this type of machine is to record continuously, matter of too great length to be included on a single record tablet. Accordingly, two duplicate phonograph units are employed, each having a mandrel for a record tablet, and each mandrel being associated with a carriage which supports a recorder carrying a stylus for recording upon a sound record mounted thereon. Mechanism is employed for causing the alternate operation of the two units in such a manner that when the record tablet on the mandrel. of one machine is exhausted, or its limits reached, the other machine or unit will automatically be put into operation. The first tablet now may be removed, and a third substituted therefor. This alternate operation-of the machines, and substitution of record tablets, may be continued until the endof the speech or message, or as long as the operator desires. h

The present invention provides a novel arrangement of electrical and mechanical elements which may be operated automatically to supply energy or power to drive the second phonograph unitto start recording, when the recorder of the first phonograph unit which has previously been put in operation, approaches the end of its record-cylinder, and subsequently to cut off the supply of electrical energy for driving the first 4 unit.v While the supply is thus cut ofif from the first unit, the latter may be reconditioned for recording by substituting a new record for the used tablet and returning the recorder to starting r position. As the carriage of the second machine reaches the end of its sound record, it automatically closes the electrical circuit of the first unit, and starts its operation, and subsequently cuts off the source of driving energy from the second 'lated current received from an amplifying system such as, for example, that disclosed in United State's Patent No. 1,823,717 to .H. S. Worrell, issued September 15, 1931. Each of the twinphonograph units receives current from the same amplification unit. The present invention provides a novel arrangement of electrical and mechanical means for connecting the recorder of either unit to theamplifier when that unit is set in operation, as described above, and subsequently disconnecting the recorder of the said unit simultaneously with discontinuance of the drive thereof.

The twin-phonograph shown in the present drawings comprises a sub-base I which is hinged or otherwise mounted ona support (not shown). Upon the sub-base I, a pair of base-plates 3 are suitably secured to the base side by side; by

screws 5. A pair of duplicate phonograph units,

hereinafter referred to as unit A and unit B, are mounted upon the base-plates. In the following description, it should be understood that the details described with reference to one unit are exactly duplicated in the second unit. Each of the phonograph units comprises a housing I which provides a bearing for a rotatable mandrel 9 and for a freely rotatable pulley The mandrel 9 is adapted to support a record-cylinder l3 of wax-like material, upon whicha helical sound groove may be engraved by means of a recording stylus l5 in a well-known manner. I

Near the right end of the base-plate 3 a front standard l1 and a back standard I9 are located, see Fig. 2. Between these standards and the housing I there is supported a front carriage rod 2|, 9. backcarriage rod 23, and a rotatable feedscrew 25. Upon the rods 2| and 23, and adapted to be moved longitudinally of the record-support or mandrel 9, a. recorder carriage 21 is located..

The recorder carriage supports an electro-mag- -netic recording device of; any suitable construction. V

A brief description of the assembly and operation of the pulley II, the mandrel 9, the carriage 21, and the feed -screw 25 is as follows: The pulley II is preferably driven by an elec trio motorindicated at 3|,by means of a driving belt 33. The pulley drives the mandrel 9 directly, through a suitable driving shaft (not shown) and also drives the feed-screw 25 from,

the; mandrel shaft through a suitable train of gears (not shown), and with a proper change in speedwhereby the carriage 21 may be moved longitudinally along the rods 2| and 23 at a desired rate. A driving connection between the feed-screw 25 and the carriage 21 is effectedby meansof a feed-nut 35 suitably pivoted by a pin 31 in a U-shaped slot 39 formed in'the carriage 21. The feed-nut 35 is controlled by a control 'lever 4|, also rotatabiy mounted in the U-shaped slot 39. When the control lever 4| is raised, a lobe 45 engages a knob portion 41 of the feednut 35 and rotates the feed-nut to lift it out of engagement with the feed-screw 25, and at the same time a lobe 49, also on the control lever 4|, engages a pivotally mounted stylus-carrier 5| to lift the stylus |5 out of engagement with the record-cylinder l3. In normal operation of the machine the recorder carriage starts its operation at its farthest position to the left. Although this position is not shown, it is substantially indicated by the position of the carriage extension bar 26 of the unit B machinein Fig. 2. At the start of the operation a handle 40 of the control lever Al is lowered so that the recording stylus I5 is also lowered into engagement with the recordcylinder l3 and the feed-nut 35 is yieldingly held in engagement with the feed-screw 25 by means of a spring 53, as shown in Fig. l. The operation of the machine is so controlled that under normal operating conditions the carriage drive for each unit is automatically stopped before the feednuts 35 run off of the threaded portion of the feed-screw 25.

As shown in' Fig. 4, the recorder 29 of each unit A and unit B is connected with a power amplification unit generally indicated at 59. The one power amplifier may be connected to supply either or both of the recorders 29 with sound wave modulated electric current. There is also shown connected with the power amplification unit 59 a microphone 6|, for translating sound waves into electrical current modulations.

The wiring system. for the motors 3|, and for the amplifying means, is diagrammatically shown in Fig. 4. The motors 3| are preferably driven by means of the usual electrical energy supplied to an office building or the like, indicated by main power lines 63 and 65. The motors 3| are connected with the main lines through a. main switch 69 and terminals 13 and 15. The circuit connecting the motor 3|A of unit A with the terminals 13 and 15 is as follows: a lead 11 .connects the terminal 13 with the motor 3|A, a lead 19 connects the motor 3|A with a change-over switch generally indicated at index S, and a return lead 8| connects the switch S with .the ter- 3:, minal 15.

The motor 3|B of the unit B machine is connected with the terminals 13 and 15 as follows:

a wire connects the motor 3 IB with the switch S, and the return wire 8| connects the switch S 49 with the terminal 15; a wire 83 connects motor 3|B with the terminal13.

The power amplifier 59 is connected with the recorders 29A and 29B of the units A and B respectively as follows: a line 91 provides an elec- 43 trical connection between the amplifier and a change-over switch generally indicated by index S; a line 89 connects the switch S with the recorder29A of the unit A machine. A'line 9| connects the switch S with the recorder 29B of the unit B machine. A common return line 93 connects 'the' recorders of both units A and B with the power amplifier 59.

It is desirable that the switches S and S should be able to connect either or both of the motors of the units A and B with the power line, and either or both of the recorders of the units A and B with the amplifier 59. For accomplishing such a result I may use any of the known mechanical switches, but in the present embodiment of the 60 invention I have found it expedient to use mercury switches such as areshown in Figs. 1, 3, 4 and 5. As the switches S ami S may be identical, it is necessary to describe only one. The switch S comprises a tubular-shaped container 65 95, preferably formed from some dielectric material such as glass, having wells or hollow projections 91,99 and llll extending from the bottom thereof, as shown in Fig. 4. The container 95 is sufficiently filled with a fluid electrical con- 70 ductor such as mercury I93, so that when the container 95 is in a level position and the wells 9], 99 and IM are extending downwardly, the mercury I03 will fill all of the wells, and stand above the top of the wells to provide-an electrical 75 aosasoe connection between them all. The container is mounted so .that it can be tipped at an angle to the horizontal, causing the mercury I03 to flow to the lowered end thereof, when the upper well will be cut off from the other two. For example, the switch S is shown in a tipped position in Fig. 5, in which the wells 91 and 99 are lowered and the mercury I03 has flowed to the lowered end to break the mercury connection between the well IOI and the other remaining wells 91 and 99.

The interior of the wells 91,. 99 and IOI are connected with the leads or wires 19, 8I and 85 respectively. It is evident, with the switch S in the position shown in Fig. 4, and with the switch 69 closed, that electrical energy will be supplied from the lines 63 and 65 to the motors 3IA and 3 IB rendering both units operative to travel along their respective record-cylinders. But, by tipping the switch S, as shown in Fig. 5, the electrical connection to the motor 3IB of the unit B -machine is broken, rendering the B machine inoperative. Also, it is evident that by tipping the switch S in the opposite direction, the motor 3IA of the A unit will be disconnected, putting the A unit out of operation.

The supply of electrical energy-to the termi-' nals 13 and 15, and consequently to both of the motors 3|, may be discontinued by the manually controlled switch 69.

As above pointed out, the switch S isidentical in construction to the switch S; and it is clear that both of the recorders'29A and 29B of the unit A and B machines are electrically connected. with the amplifier 59 when the switch S is in the position shown in Fig. 4.

The electrical energy from the amplifier 59 enters the well 99', fiows through mercury I03 to the well 91', to the recorder 29A of the unit A machine by wire 89, and then back to the amplifier 59 by the common return lead 93. Likewise,

the well 99' is connected with the well I M by the mercury I03 and the current 'fiows from the well IN to the recorder 29B of the unit B machine over the wire 9|, and thence to the amplifier 59 by the commonreturn lead 93.

In the Figure 5 position of the switch S the recorder 29B of the unit B machine is cut out while the recorder 29A of the unit A machine is left in. When the switch S is tilted to lower the well IN the unit A machine sound recorder is cut out and the recorder of the unit B machine cut in. I

From the above description, it is clear that a. novel switching arrangement is provided for the simultaneous control of the motors 3I and the recorders 29 of the unit A and Bmachines, whereby either or both of the motors 3| may be energized, and either or both of the recorders 29 may be connected with the amplifier 59.

I will now describe certain other novel features of the invention by which the switches S and S are controlled or positioned to effect an alternate operation of the units A and B. I The switches S and S are mounted upon an oscillating arm or lever I 01 pivotally mounted near its center upon a bracket I09 by means of a stud III.

Y Bracket I09 is adjustably mounted on the under side of the sub-baseI by means of screws IIO (Fig. 2) which pass through slots 2 formed in the bracket I09. It is evident from the manner in which the bracket I09 is thus mounted on the sub-base Ithat the position of the bracket I09 may be adjusted longitudinally of the sub-base I by loosening the screws H0 and sliding the bracket I09 in one direction orthe other so that the screws IIO assume intermediate positions in the slots II2.

The switch S is mounted at the upper end of arm I01 by spring clips H3. The switch S is secured to the lower arm of the lever I01 by means of similar clips II3. Thus, as the lever I01 pivots about the stud III, the containers 95 and 95' of the switches S and S respectively are tipped, so that the mercury flows to the lefthand ends of the containers when the lever I01 is swung in a counter-clockwise direction (as viewed in Fig. 4) and to the righthand ends of the containers when the lever I01 is swung in the opposite direction.

A description of the mechanism for controlling the circuits which contain mercury switches S and S is as follows (see Figs. 1, 2 and 3) A lever H1 is pivotally mounted adjacent one end on the underside of the sub-base I between the twin machines by means of a stud II9. At the end of the long arm of the lever I I1 is a post 2 I 2|, which extends through a slot I23 formed in in the base-plate into the path of the carriage arm 26 of the unit B machine. The pivoted end of the lever I 21 also has an angle portion I3I extending therefrom, as is clearly shown in Figs. 2. 6, '7 and 8. It is evident that the levers H1 and I21 may be swung about the stud II9 by the com 3 tact of the carriage extension bars 26 of the units A- andB respectively. The carriage arm 26 of the .unit A machine is adapted to move the arm of the lever II1 about the stud H9 in a counterclockwise direction (asviewed in Fig. 2). carriage arm 26 of the unit B machine is adapted to move the lever I21 about the stud H9 in a clockwise direction (as viewed in Fig. 2). The levers H1 and I21 are spaced from the sub-base I by means of a collar I20. The motion of the arms or levers H1 and I21 is transmitted to the switch lever I01 by means of a connecting lever I33, and a motion'multiplying lever I 35. The lever I33 is pivoted near one end on the stud H9, and is located beneath the two levers H1 and I 21. The mechanical interconnection between the levers II1, I21 and I33 is made resilient as follows: the pivoted end of the connecting lever I33 has a turned up and or finger I31, against which the opposing edges of 5 the angle portions I25 and I3I of the levers H1 and I21 abut. The proportioning of the width of the finger I31 and the portions I25 and,I3I is such that when the latter portions are abutted The 4' against the finger I31, the levers H1 and I21 are (11) alignedwith each other. The levers H1 and I21 are normally held in this aligned position, by

means of a tension spring I39 which extends be- 4- the action of the angle portions I25 and I3I on the finger I31.

The multiplying lever I35 is pivoted above its center to the bracket I09 by means of a stud I05. It has a finger I34 extending from the top thereof, and passing through a slot I43 formed in the free or long arm of the connecting lever I33.

Thus the movement of the connecting lever I33 about the stud I I9 is transferred to the motionmultiplying lever I35. The latter lever transfers its motions to the lever I01 by means of a pin I41 mounted on the lever I01, a little above the stud I I I. The pin I41 extends through an opening I49 formed in the bracket I09, and into a. slot I5I formed in the lower end of the motionmultiplying lever I35.

The operation of the lever and switch system will be described in connection with Figs. 2, 6, 'l and 8, which show the different positions which the parts assume under different conditions of operation of the twin-machine.

Record-cylinder blanks I3 are placed on the mandrels 9 of the phonograph units A and B, and

the recorder carriages 21 are moved to the starting position (the left-hand position as shown in Fig. 2 by the carriage arm 26 of the unit B).

Then the control levers 4| of both units are manipulated to position the styli to engage their respective record-cylinders, and the feed-nuts to engage their respective feed-screws. Both units are nowin condition to-operate whenever the respective mandrels are set in operation by the respective motors 3|. The units A and B as described may be used for the purpose of recording telephone conversations and messages; therefore it should be understood thatthe recorders 29may be of any suitable construction designed for electrical recording and may be connected by any suitable means to divers kinds of sound sources.

After the recorders are conditioned for soundrecording, the operator, if he desires to have the unit A operate, rather than the unit B, sets the lever system to the position shown in Fig. 6 to swing the switches S and S'to the position shown in Fig. 5, in which position the motor 3| of the unit A is electrically connected with the terminals '13 and 15 through the switch S and the recorder 29 of the unit A is electrically connected with the amplifier 59. As hereinbefore pointed out, in

this position of the parts the electrical connection is broken between the motor 3| of the unit B machine and the terminals 13 and 15 and the recorder 29 of the unit B machine is also disconnected from the amplifier 59. It now the operator closes the switch 69, the electrical en'- ergy from the main lines 63 and is available to the motor 3I' of the unit A and the unit A machine is placed in full recording operation.

The belt 33 is caused to travel under the infiuence of the driving pulley 51, to rotate the pulley II, to drive the mandrel9, and the feedscrew 25. with this operation of the machine, the recorder 29 ofthe A unit will travel over the record to cut a spiral sound groove. The sound groove records the sound waves picked up by the microphone H, and it will be particularly noted hereinafter how. the twin-phonograph machines function to make possible a continuous record of a telephone conversation, public speeches, etc.

the stud forwardly (in the direction of the arrow as indicated in Fig, 6). In this way, the lever II1,is moved counterclockwise around the stud |I9. Because of the tension of spring I39, lever I21 moves with lever II1 to maintain its align- 5 ment therewith and cause rotation of lever I33 about pivot II9. By this motion of the connecting lever I33 the motion-multiplyinglever I35 is moved about the stud I45, and the motion of the multiplying lever I35 is transferred to lever I01, to gradually move the switches S and S from the Fig. 5 and Fig. 6 position to the Fig. 2 and Fig. 4 position. Asa result the switches S and S connect the unit B machine with the respective sources of. electrical energy, and the unit B machine is set in recording operation. It is to be noted that as hereinbefore pointed out, the switches S and S in the Fig. 4 position (in the mid position) connect both of the units A and B with electrical energy and consequently both of 20 the machines are operated simultaneously.

Continued operation of the unit A machine, however, advances the carriage arm 26 still farther toward the end of its travel and this continued movement of the arm 26 moves the levers 25 I|1, I21 and I 33 about the stud I9 to move the arm I01 to such a position as to tip the switches S and S and disconnect the motor 3I and the recorder 29 of the unit A machine from theirrespective sources of power, and accordingly the 30 recording operation of the unit A machine is stopped. This position of the lever system is shown in Fig. 7, and it isnoted that in this position the posts I2I and I 29, and their respective arms or levers H1 and I21 are in a position (11- 35v rectly opposite from that shown in Fig, 6.

Thus for a short interval, during the movement of the switches S and S through an arc, both machines A and B are operatedyseveral factors are involved in determining the length of the 40 interval during which both of the machines are operated by the switches S and S. It is preferable that these factors be correlated in such a fashion that an overlap of from four to eight sound grooves be eflected. The amount of over- 45 lapping, however, may be changed as desired, by changing the correlation between the factors; for example, if a longer overlapping period is desired, the mechanical advantage of the connecting lever I33 may be changed, thus making a greater throw 50 of the arm I I1 necessary to shut off the motor of the unit machine which is just finishing its recording operation.

-As the recording operation of the unit B machine now continues, the unit A machine may 55 be reconditioned for recording by changing the old record for a new record, and positioning the recorder carriage 21 in its starting position, at the left of the machine.

As the recording operation of the unit B machine continues, the carriage arm 26 of the unit B machine moves forward, as shown in Fig. 7, until finally it contacts with the upstanding stud or post I29. Further motion of the arm 26 now moves the post I 29 forwardly to move the arm or lever I21 in a clockwise manner, whereby the, armor lever I01 is moved in a counter-clockwise manner aboutthe stud III, and the switches S and S are moved to neutral position and the unit A'machine is restarted. As before, the two machines A and B now operate simultaneously during the overlapping period. However, the continued movement of the arm 26 of the unit B macfine moves the post I29 forwardly to return the switches S and S to the position shown in Fig. 5, in which position the unit B machine is cut off from all electrical energy.

. Although in Fig. 7 the carriage arm 26 of the unit A machine is shown in contact with the upstanding post I2I, it is to be understood that in the usual operation of the two machines as a unit, the carriage 21 of the unit A machine would have been repositioned in starting position, and accordingly the arm 26 would not be in the posi- -tion shown in Fig. 7 but in a position similar to that of the arm 26 of the unit B machine in Fig. 2. From the above description is is clear that the units A and B may be operated to record a lengthy speech or other matter without interruption, and that when the respective carriages reach the ends of their recording operations, one machine will be put into recording operation before the other machine is "stopped; there is no opportunity for any hiatus occurring in the recording of a speech. Further, the amount of overlapping may be nicely adjusted at the fac' tory, or later by the operator, by changing the position of the bracket I09 with respect to its spacing from the stud I I9 whereby the mechanical advantage between the levers H1 and I21 and the finger I34 of the multiplying lever I35 is changed. By moving the bracket I09 closer to the stud II9 the mechanical advantage may be reduced, and a longer time interval or overlap provided between the starting of one of the machines and the stopping of the other. By moving the bracket away from the stud II9 the mechanical advantage may be increased and the length of the period of the overlapping interval may be reduced.

The purpose and operation of the resilient connection betweenthe levers H1 and I21 and the connecting link or lever I33, and consequently the resilient connection between the connecting link I33 and the carriage arms 26 of the unit A and B machines may be described as follows:

Although under normal operation of the two machines A and B as a unit, the machine which has just finished its recording operation. is re-- turned to its starting operation while the other machine is continuing its recording operation, it is possible that the operator may forget to recondition the machine which has just completed chine, referring to Fig. 8, would tend to move the lever I21 in a clockwise manner about the stud H9. But the movement would be resisted by the pressure of the arm 26 of the unit'A machine against the post I2I. (It is assumed for the purpose of explanation that the arm 26 of the .unit A machine was, left in its finished recording position, in Fig. 8, with its feed-nut 35 in contact with the threaded portion of its feed-screw 25, and that the arm 26 of the unit B machine moved to its finished recording position subsequent to the finishing of machine 'A.) It is evident that if the levers H1 and I21 constitute a rigid lever, the continued movement of the arm 26 of the B machine toward the position of Fig. 8 might cause breakage of some part of the ma chine, burn out a motor or do other damage. However, my resilient leverage system provides agains such damage in the event that the operator f rgets to recondition the machine which As hereinbefore described, the action of the spring I39 holds angle portions I3I and I25 of the arms I21 and H1 respectively against the finger I31, and although thearms H1 and I21 are normally restrained in a straightline position, and although the connecting link "I33 is nor- 5 mally restrained in a position which is substantially perpendicular to the arms I I1 and I21, they may be moved from this normal position under the peculiar circumstances set out above. Thus, assuming that in the Fig. 8 position the arm 26 10 of the unit A machine were left in its finished recording position, then forward movement of the arm 26 of the unit B machine rotates the arm I21 in a clockwise manner about the shaft H9; but because the arm 26 of the unit A machine resists the corresponding clockwise and reverse rotation of the movement of the arm II1, the latter armremains stationary, and the angle portion I3I of the arm I21 moves out of contact with the finger I31 of the connecting lever 20 .I33, against the action of the spring I39, which is now stationary. As a result the lever I01 ,on which the switches S and S are mounted is '21 ceases, although the motor 3| of the unit B 35 machine continues to rotate.

From the above operation, it is clear that no damage will result to the machine in the event that the operator forgets to return an inactive recorder to its starting position. The result would be merely to cause the motors to run idle until such condition be discovered and remedied.

The aboveoverlapping feature described for the two phonograph units, as pointed out, is particularly desirable when recording lengthy tele- 45 phone conversations, etc. The arrangement enables the transcriber to determine the proper sequence of cylinders (or relationship of cylinders) because the first few words of one cylinder will correspond exactly with the last few words of 60 the preceding cylinder.

An advantage of the present embodiment of the invention is the arrangement of the two units A and B side by side, with their respective mandrel shafts pointing in the same direction, and the return movement of the carriage 21 is also in the same direction. Thus the operation of the two units issimplified, and the possibility of the operator becoming confused in the manipulation of the machine is eliminated. In fact, 60 the machines may be more effectively and accurately operated than twin-phonographs arranged with their mandrels in coaxial alignment but extending in opposite directions. 7 By the provision of separate motors for the individual units, a more positive operation isobtical nature, well adapted to attain the several objects of this inventibn. v As many possible embodiments may be made of the above invention without departing from tric motor for driving the sound-record support and carriage; a source of power for said motors; a switch for connecting said power with either or both of said motors; and a system of mechanically connected levers capable of establishing a mechanical connection between said carriages and said switch as said carriages approach the end of a recording operation.

'2. In appartus of the class described, in combination, two sound-recording machines mounted on a common base, each machine having a soundrecord support, a recorder carriage, and an electric motor for driving the sound-record support and carriage; a source of power for said motors; a switch for connecting said power with either or both of said motors; and a system of mechanically connected levers capable of establishing a mechanical connection between said carriages and said switch as said carriages approach the end of a recording operation, whereby as one machine finishes its recording operation it is mechanically interconnected with said switch and moves said switch to start the recording operation of the second machine and subsequently to stop the recording operation of the first machine.

3. In apparatus of the class described, in combination, two sound-recording machines mounted on a common base, each machine having a record-support and a carriage, and driving means for rotating said record-supports and for driving said carriages longitudinally with respect to said record-support; a source of power for said driving means; a double throw switch for connecting said source of power with either or both of said driving means; and meansfor changing the position of said switch to start the recording operation of one machine as the other machine finishes a recording operation, and then subsequently to stop the recording operation of the finishing machine, said means being operable by the carriages of the respective machines in succession.

4. In apparatus of the class described, in combination, two sound-recording machines mounted on a common base, each machine having a record-support and a carriage, and driving means for rotating said record-supports and ,for driving said carriages longitudinally with respect to said record-support; a source of power for said driving means; a switch for connecting said source of power with either or both of said driving means; and means for changing the position of said switch to start the recording operation of one machine as the other machine finishes a recording operation, and then subsequently to stop the recording operation of the finishing machine, said means comprising a system of mechanically connected levers capable of establishing a mechanical interconnection between said carriages and said switch as said carriages respectively approach the end ofa recording operation.

5. In apparatus of the class described, in com bination, duplicate successively operable soundrecording machines, each comprising a recordsupport and a recorder carriage and each being driven by a separate electric motor; a pivotally '5 mounted switch for connecting a source of power with either or both of said machines; and means for changing the position of said switch to start the recording operation of one machine as the other machine finishes a recording operation, and 10 then subsequently to stop the recording operation of the finishing machine, said means comprising a jointed and resiliently biased lever mounted on a pivot, a connecting lever also mounted on said pivot and capable of rocking said switch, said connecting lever being constrained to rotate with said jointed lever about said pivot, and

-means on said jointed lever positioned in the paths of travel of said carriages.

6. In apparatus of the class described, in com- 20' binatlon, duplicate successively operable soundrecording machines, each comprising a recordsupport and a recorder carriage and each driven by a separate electric motor; a pivotally-rnounted switch for connecting a source pf power with either' or both of saidmachines; and means for changing the position of said switch to start the recording operation of one'machine as the other machine finishes a recording operation, and then subsequently to stop the recording operation of the finishing machine, said means comprising a jointed lever. mounted on a pivot,-a connecting lever also mounted on said pivot, and capable of rocking said switch, said connecting lever being resiliently constrained to rotate with said jointed lever about said pivot, and upstanding abutments mounted on the free ends of said jointed levers capable of intercepting the path of said carriage, whereby each carriage moving into finishing position contacts with its respective abutment and the interconnecting lever changes the position of the switch to start the other machine in recording operation, said jointed lever and interconnecting lever being adapted to prevent injury to the machines should both carriages reach the finishing position.

'7, In apparatus of the class described, in combination, duplicate normally successively operable sound-recording machines, each comprising a record-support and a recorder carriage and each driven by a separate electric motor; a switch for connecting a source of power with either or both of said machines; and a'lever system for mechanically connecting said carriages with said switch, whereby as the carriage of one machine of the first machine, said lever system comprising two levers resiliently connected to actas a single lever pivoted at its center, abutments carried by said single lever on either side of said center, each abutment being capable of contacting with one of said carriages, the arrangement being such that when one abutment is contacting with its carriage the other abutment is free to move under the influence of the contacting abutment, but in the event that both carriages con-' tact with their respective abutments, the abutments may move independentlyof one another because of the resilient connection of said levers.

8. In apparatus of the class described, in conibination, two sound-recording machines mounted on, a common base, each having a record- 76 aoaasos point, and means whereby said fluid switch may.

be operated for successive reversals by the carriages of the respective machines.

9. In apparatus of the class described, in combination, two sound-recording machines mount- I ed on a common base, each having a record-support, a movable carriage, and independent drivmeans for rotating the record-support and for moving the carriage longitudinally of the rec-- ord-support; a source of power for said driving means comprising a rockable fluid switch; and means for connecting said source of power to either or both of said driving means, said means being operable by one of said carriages as it approaches the end of its record to start the other carriage and record-support by connecting said source of power with the other driving means, and being further operable to stop said first carriage and record support assaid carriage moves farther toward the end of ,said record-support, said means being operable successively first by one carriage and then by the other to produce continuously successive operation of said machines.

10. In apparatus of the class described. in combination, two sound-recording machines mounted on a common base, each having a record-support, a movablecarriage, and independent driving means for rotating the record-sup port and for moving the carriage longitudinally of the record-support; a source of power for said driving means; and means for connecting said source of power to either or both of said driving means, said means being operable by one of said carriages as it approaches the end of its record to start the other carriage and record-support by connecting said source of power with the other driving means, and being further operable to stop said first carriage and record-support as said carriage moves farther toward the end of said record-support, and said means also being operable by said second carriage to start said first-named carriage, and to stop said second carriage.

11. In apparatus of the class described, in combination, two sound-recording machines mounted on a common base, each having a record-support, a movable carriage, and independent'driving means for rotating the record-support and for moving the carriage longitudinally of the record-support; a source of power for said independent driving means; a switch for connecting either or both driving means to said source of power, a lever system responsive to carriage op eration for operating said switch, said switch being operable by means of said lever system by one of said carriages as it approaches the end of its sound-record to connect the source of power with the driving means of the other carriage to start said other carriage at the beginning of a record, and upon continued movement of said first-named carriage to disconnect said source of power from the driving means of said first-named carriage.

12. In apparatus of the class described, in combination, two sound-recording machines mounted on a common base, each having a record-support, a movable carriage, and independent-driving means for rotating the record-support and for moving the carriage longitudinally of the record-support; a source of power for said driv-' ing means, switch means for connecting either or both of said driving means to said source of power, a lever: system responsive to carriage operation for operating said switch, said switch "being operable by means of said lever system by one of said carriages as it' approaches the end of its sound-record to connect the source of power to the driving means of ther other carriage to start said other carriage, and upon continued movement of said first-named carriage to disconnect said source of power from the driving means of said first-named carriage, and said secondnamed carriage as it approaches the end of its sound-record being adapted to operate said switch by means of said lever system to connect the source of power with said first-named driving means, to start said first-named carriage and upon further movement of said second-named carriage to disconnect said source of power from the driving means of said second-named carriage.

13. The combination of two duplicate successively operated sound-recording machines, each comprising a record-support, a recorder carriage, and an electric driving motor, and means comprising a pair of co-pivotal levers spring-biased normally to act as a single lever responsive to the operation of said carriages for controlling con nections to said motors to control the said operation of said carriages.

14. The combination of two duplicate successively operated sound-recording machines, each comprising a record-support, a recorder carriage, and an electric driving motor and means comprising a pair of co-pivotal levers spring-biased normally to act as a single lever responsive to the 5 operation of said carriages for controlling connections to said motors to control the said operation of said carriages, and respectively independently operable in response to operation of said carriages without effect upon the conneciions to said motors and the operation of sa.d carriages.

15. The combination of two duplicate successively operated sound-recording machines, each comprising a record-support and a recorder carriage, means comprising a pair of co-pivotal levers spring-biased normally-to act as a single lever, a changeover switch for controlling the operation of said carriages, and means for efiecting the operation of said switch by one of said levers when the other of said levers is actuated by one of said carriages.

I 16. The combination of two duplicate successively operated sound-recording machines, each comprising a record-support and a recorder carriage, a pair of co-pivotal levers, a spring connecting said levers normally compelling action thereof as a single lever, a change-over switch for controlling the operation of said carriages, and means for efiecting the operation of said switch by contact with one of said levers when the other of said levers is actuated by one of said carriages, said other lever being incapable because of said spring connection efiecting the operation of said 76 switch through contact with said means so .long as the said one lever is effective.

17. The combination of two duplicate successively operated sound-recording machines, each comprising a record-support, an electrical recorder and a recorder carriage; electrical driving means for each of said machines; electrical energizingmeans for said recorders; a switch for controlling the operation of said driving means; a switch for connecting said energizing means to said recorders; means mounting said switches for simultaneous operation; and means responsive to operation of said carriages for actuating said switches.

18. In apparatus of the class described, in combination, duplicate sound-recording machines each having a record-support, a carriage, and driving means for rotating the record-support and driving the carriage; a source of power for said driving means; a switch movable between extreme positions for connecting said source of power with either, through a mid position for connecting said source of power with both of said driving means; a system of motion-transmitting" elements for shifting said switch comprising a pair of reciprocatively and rotatively connected levers adapted to pass through a dead center position to cause a reduced rate of motion of said switch during the mid portion of its movement from one extreme position to the other; and means responsive to operation of said carriages for actuating said system of elements.

19. In apparatus of the class described, in com bination, duplicate sound-recording machines each having a record-support, a. carriage, and

driving means for rotating the record-support and driving means; a switch movable between extreme positions for connecting said source of power with either or both of said driving means; a system of motion-transmitting elements for shifting said switch comprising a pair of reciprooatively and rotatively connected levers adapted .to pass through a dead center position to cause a variation in the rate of motion of said switch during its movement between said extreme positions; and

means responsive to the operation of said carriages for actuating said system of elements.

20. In apparatus of the class described, in combination, duplicate sound-recording machineseach having a carriage and driving means adapted to move the carriage at a substantially uniform rate; a source of power for said driving means; a switch for connecting said source of power with either or both of said driving means, and mechanism actuatable successively by the respective carriages to cause the uniform movement of the carriages to impart movement to said switch at a variable rate.

' 21.- In apparatus of the class described, in combination, two sound-recording units each having a sound-recorder carriage and -an electric motor for driving the carriage; a source of power for said motors; a switch for connecting said power with either or both of said motors; and a mechanical transmission system capable of establishing a con-.

nection for transmitting motion between said carriages and said switch as said carriages approach the end of a recording operation, said system comprising means for adjusting the sys-. tem to transmit motion at different predetermined rates.

LELAND D. NORTON.

JOHN E. RENHOLDT.

CERTIFICATE OF CORRECTION.-'

Patent No. 2,026,398.

LELAND D. NORTON, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 7, first column, line 24, claim 9, strike out the words "comprising a rockabl'e fluid switch' and insert the same after "'means" in line 25,. same claim; and second column, line 75, claim 16. before "effecting" insert of; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in .the Patent Office.

Signed and sealed this 3rd day of March, A. D. 1936.

Leslie Frazer (Seal) Acting; Commissioner of Patents.

, December 51, 1935.

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