US2032450A - Electric sound-reproducing apparatus - Google Patents

Description

March 3, 193 6.

A.'A. THOMAS ELECTRIC SOUND REPRODUCING APPARATUS I 0riginal Filed March 1, 1929 3 Sheets-Sheet l INVENTOR March 3, 1936. A. A. THOMAS ELECTRIC SOUND REPRODUCING APPARATUS Original Filed March 1, 1929 3 SheetsSheet 2 via A. A. THbMAs 2,032,450

March 3, 1936.

I ELECTRIC SOUND REPRODUCIN-G AP PARATUS A 3 Sheets-Sheet 3 Original Filed March V1, 1929 'INVENTOR Patented Mar. 3, 1936 PATENT OFFICE Emo'rmo .SOUND-REPRODUCING APPARATUS Adolph A. Thomas, New York, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application March 1, 1929, Serial No. 343,627 Renewed November 12, 1935 25 Claims. (01. 274-10) 10 were employed, each with its own motor and re-,

producer, and automatic synchronizing mechanism of complicated structure was necessary to start the second phonograph just before the record oi the first machine reached the end of its.

15 travel. Such a piece of apparatus was not only intricate, but very expensive, and whollyunfit for household use.

It is the object of my invention to provide a I multiple-disk phonograph in which disk records are automatically played in pairs, each pair having a single reproducer. The basic feature of my machine comprises a pair of records arranged to rotate simultaneously in opposite directions and in contact with each other at the edge. The first record is played from the center toward the edge, and the second is played from the edge toward the center by the same reproducer. The spiral tracks of the two contiguous records are united across their peripheral point of contact, thus 30 forming a double continuous spiral running from the center of the first record to the center of the second. The reproducer travels along a diametric line across the two records, which are supported on their respective turntables in such relation as to unite the spiral tracks at the point of contact; It more than one pair of records are used, I make provision for automatically starting the operation of a succeeding pair of records when the reproducer of the preceding pair is at the end of the 40 spiral groove. These automatic starting connections are quite simple and involve little more than a mere duplication of turntables and driving motors. For a household machine, one pair of turntables is sufficient; and in a machine designed for 45 talking-movie equipment, not more than two pairs of turntables are needed.

The novel features and practical advantages of my improved phonograph will be understood from a description of the accompanying drawings, in 50 which- Fig. 1 is a diagrammatic plan view of a pair of disk records constructed and arranged in accordance with my invention to provide a continuous playing groove from the center of one record t 55 the center of the other;-

Fig. 2 represents a portion of the contiguous records on an exaggerated scale to show more clearly the uniting of the two spiral grooves across the point of contact;

Fig. 3 is a cross-section of Fig. 2 on line 3-4; 5

Fig. 4 shows the mounting of the reproducer and electromagnetic means for normally holding it out of playing position;

Fig. 5 isa plan view of the machine for one pair. of turntables; A

Fig. 5a illustrates the details of a motor-controlling switch used in Fig. 5;

Fig. 6-is a front view of Fig. 5, partly in section, to show certain parts beneath the motor board;

Fig. 7 is a plan view of a machine having two pairs of turntables and circuit connections for automatically starting the operation of the second pair of records; 4

Fig. 8 shows the reproducer in side view at the end of the spiral groove, which is adapted to close one of the controlling circuits indicated in Fig. 7;

Fig. 9 is a rear view of thereproducer;

10 is a plan view, partly in section, showing the mounting of the reproducer and the electromagnet which releases the reproducer arm at 95 a predetermined moment; and

Fig. 11 shows an enlarged detail of a motor switch operated by the reproducers in the machine of Fig. 7.

The basic idea of my invention is diagrammatically represented in Fig. 1, where we have a pair of disk records Ill and 12 mounted on turntables to rotate simultaneously in opposite directions at the same speed. The central circles I3 and I4 may be regarded, as the turntable shafts on which the records rotate. The record H) has a spiral sound groove l5 playedfrom the center toward the edge, and the record I! has a spiral sound groove l6 played from the edge toward the center. It is understood, of course, that these 40 sound grooves are indicated merely in a diagrammatic way. In the actual records these grooves are exceedingly fine and run to several hundred linesper inch. The circle I! at the center of record [0 is a starting groove for the stylus of the as reproducer and leads into the spiral sound groove l5 at the point I8. The record I! has a circular groove l9 at the center into which the stylus is automatically guided after leaving the spiral track Hi. This track may be assumed to end at the point 20, which is diametrically opposite the starting point [8 of track I5. The imaginary line 2| indicates the path of travel of the playing stylus,

as will be more clearly understood after I have described the mounting of the reproducer.

' ginning at I8 and ending at 20.

The terminal portion 22 of spiral groove l5 and the initial portion 23 of spiral groove l6 extend toward each other in alignment and unite at the point 24, which lies in the imaginary line or path 2| traveled by the playing stylus. We thus have a substantially continuous sound groove consisting of two opposite spirals I5 and I6 be- To obtain this continuous double sound groove, the records l9 and I2 are mounted in contact at their peripherles. It is advisable to use suitable means for holding the playing surfaces of the records in alignment at the place of contact. A simple way to insure this alignment, is to provide one record with a peripheral groove 25, and the other record with a peripheral projection 26 adapted to fit into the groove 25, as best shown in the exaggerated view of Fig. 3. The records are thereby interlocked at the point of engagement and yet are free to rotate in opposite directions, as indicated by the arrows 21 and 28 in Fig. 1. It is necessary to place the records l0 and i2 on the turntables in predetermined relation, so that the spiral grooves l5 and I6 shall unite at the point '24 every time the outer ends of the grooves cross the diametric line 2 I. The proper positioning of the records may be compelled by the simple expedient of providing the turntables with pins and the records with correspondingly arranged holes to receive the pins. For example, in Fig. 1 the turntable of record In has a pin 29 which passes through a hole in the record, and the turntable of record l2 has two pins 30 which pass through correspondingly arranged holes in the record. This arrangement of pins and holes compels the mounting of the two records on their turntables in one position only, so that the spiral grooves l5 and IE will unite at 24 every time the rotating records reach 'the position illustrated in Figs. 1 and 2.

If a playing stylus is so mounted as to move laterally in a path indicated by the imaginary diametric line 2|, it is evident that the stylus point will travel without interruption from the starting point I 8 of the spiral groove |5, across the point 24 into the spiral groove l6, finally reaching the circle |9.' By making the peripheral projection 26 with a slanting edge, as shown in Fig. 3, the stylus point will always be guided safely from the terminal portion 22 of spiral |5 across the bridging point 24 into the initial portion 23 of spiral groove l6. Ordinarily, the transition of the playing stylus from one record to the other will not be noticed acoustically, but even if there should be a brief interruption at the moment when the stylus crosses the point 24, it will have no marring or objectionable efiect on the reproduction. In all phonograph records there are pauses in the speech or music, and one of these pauses may well occur at the crossing point 24.

Referring to Figs. 5 and 6, the records I9 and I2 are placed on a pair of turntables 3| and 32, which are mounted on and rotate with the upright shafts I3 and I4, previously mentioned. The shaft l3 extends through the motor-board 33 and is supported at its lower end in a suitable bearing 34 carried by a fixed bracket 35. A sleeve or hub 36 on shaft I3 carries a gear 31 arranged in mesh with a similar gear 39 fixed on the other turntable shaft l4. The meshing point of the gears 31 and 38 is indicated at 39, where the gears are shown in section ,forclearness. The lower end of shaft |4 rests in a bearing 49. An electric motor 4| has a shaft 42 car-- Wins a worm pinion 43 arranged in mesh with a worm gear 44 on shaft I4, whereby the move ments of the motor shaft are transmitted to the turntables 32 and 3| in properly reduced ratio. In present day phonographs, the turntable is usually driven at the rate of about eight revolutions per minute. Instead of using separate gear wheels 31 and 38, it isv evident that the turntables 3| and 32 could be provided at the edge with meshing gear teeth. While only one of the shafts l3 and I4 is connected directly to the driving pinion 43, both shafts could be connected to the motor independently of each other, but that is not necessary. In the broader aspect of my .invention, any suitable driving connections may be employed to rotate the turntables 3| and 32 si-.- multaneously in opposite directions at the same speed. The motor 4! and bearing supports 35 and 40 are rigidly mounted ona suitable base 45,

which may be a board or partition in the cabinet of the machine.

, A bracket indicated as a whole by 46 is fixed on the motorboard 33 back of the turntables. This bracket, which may be a single casting of aluminum, brass and the like, comprises a base 41 and a pair of side arms 49 and 49. Screws 59, or other suitable fastening members, secure the base 41 rigidly to the motor board 33. The bracket arms 48 and 49 carry a pair of rods 5| and 52 which extend at their ends into openings in'arms 49 and 49 and are secured by set-screws 53 and 54, respectively, or otherwise. The purpose of rod 5| is to support an electric reproducer indicated as a whole by B. This reproducer may be of any practical construction adapted to play on lateral-cut or vertical-cut records, as the case may be. Since my invention is not limited to any special type of reproducer, and since, moreover, there aremany makes of electric phonograph reproducers on the market for playing both kinds of records, I need not show or describe the details of any particular construction of reproducer. It will therefore be understood that the reproducer R, represents any practical form of device, electromagnetic, electrostatic or-mechanical, for playing a phonograph record by means of a stylus 55. For lateral-cut records, the stylus 55 is a pointed needle adapted to be clamped in a socket by a. screw 56, according to the prevailing practice in devices of this kind. For verticalcut records, like those of the Edison type, the

playing stylus is usually in the form of a diamond or sapphire point permanently attached to the reproducer casing.

The reproducer R is carried by an arm 5'! which extends from a bearing sleeve 58 mounted on rod 5| for rotary and axial movement by means of ball bearings 59, as best shown in the enlarged view of Fig. 10. The supporting rod 5| is so arranged that the playing point of stylus 55 traverses the spiral grooves of records l9 and i2 along the diametric line 2|, to which reference was previously made in connection with Fig. 1. The rod 52 acts as a support for arm 51 when the reproducer is thrown back into idle or rest position, as indicated by the dotted outline 51 in Fig. 4. The ball bearings 59 permit the reproducer R to travel axially along the rod 5| with a. minimum amount of friction, and at the same time the reproducer is free to move up and down to accommodate itself to any inequalities in the horizontal plane of the playing surfaces. It

. should be noted that the only propelling power for the reproducer is the spiral sound track, which moves the reproducer along the rod 5|. Attention is called to the fact that the stylus .pivoted at 62 on a bracket 63.

point 68 lies in a plane passing substantially through the center of sleeve 58, as shown in Fig. 8, whereby the pressure exerted by the stylus is distributed evenly through the sleeve for smooth easy movement thereof along the rod 5|. This plane is substantially at right angles to the axis of rod 5|, irrespective of the fact that the rod holds the reproducer at an angle to the vertical when the reproducer is viewed from the side.

When I use only one pair of records l and I2, I provide means for automatically opening the circuit of motor 4| when the reproducer R. reaches the end of its travel. Referring to Figs. and 5a, the bracket arm 48 carries a suitable switch indicated as a whole by S. In the present instance, this switch comprises an insulated spring contact 80 and a switch lever or arm 6| The spring contact 60 is mounted at one end on an extension of bracket 63.by means of an insulating block 64. The pivoted arm 6| may be grounded to the bracket 63 and supporting arm 49. Circuit leads 65 and 66 are connected to the switch members 68 and 6|. 65 and 66 are properly connected to the motor windings, as will be understood without illustration or description. If, as suggested, the contact arm 6| is grounded, one terminal of motor 8| may also be grounded, so that the separate wire 66 is not necessary. A contracting coil spring 51 is connected at 68 to the switch lever Bi and at 69 to an extension 18 on bracket 68. When the switch lever 6| is closed, as shown in Fig. 5a, the tensioned spring 81 holds it against a fixed pin or stop I I. The pivoted lever 6| is adapted to be moved to open position by an arm or extension, 12 projecting rearwardiy from the bearing hub 58 of reproducer R.

It is clear from Figs. 5 and 5a that, when the reproducer R reaches a predetermined position on record l2, the arm 12 engages the free end of lever 6| andslowly rocks it toward the left, or in a clockwise direction as viewed in Fig. 5. The spring 61 is so close to the pivot point 62 of lever 8| that it does not interfere with the axial move-- ments of the reproducer on supporting rod 5| as the stylus point is guided by the spiral sound groove It. It requires only a slight rocking movement of lever 6| to throw the tension line' of spring 61 to the right of pivot 62, whereupon the spring 61 quickly moves the lever 6| into open position, as indicated by the dotted outline 6| in Fig. 5a.. A stop 13 limits the movement of switch lever 6| into open position by the action of spring 61. This lever is so positioned that the switch S is not opened until after the reproducer R has finished playing the record l2. It is perhaps best to arrange these cooperating parts in such a way that the switch S is opened when the stylus of the reproducer enters the terminal groove l9 of record It. It is a known fact that all phonograph records do not terminate at exactly the same point in the spiral track, and we may assume that the point 20 on record i2 (see Figs. 1 and 5) represents the farthest point to which the sound is recorded. Therefore, by automatically opening the motor switch. S when the stylus of reproducer R enters the circular groove l9, premature stopping of the record is prevented. An adjustable stop I4 may be mounted on the supporting bar 5| in such position that, when the bearing 58 engages this stop, the stylus-55 on being lowered enters the starting groove ll of record l0. To simplify Fig. 5 I have It is assumed that the conductors omitted the spiral grooves l5 and it from. the records. 4

I may provide my new phonograph apparatus with more than one pair of records, for the basic idea of my invention lends itself to the use of a plurality of pairs of records which are automatically set in operation one after the other. A construction like that is illustrated more or less diagrammatically in Fig. '7, where we have two pairs of records Ill-l2 and |0'|2'. Since the second pair of records |0'|2' and their driving connections are the same as those of the first part of records In and I2, the detailed description of Figs. 5 and 6 may be considered to apply'fully to the left half of Fig. 7. For this reason I have indicated similar parts in the two halves of Fig. 7 by like reference numerals, except that, for the sake of distinction, certain numerals in the left half carry a prime mark The reproducers R and R are supposed to be identical in structure and mounting, but that is not necessary in the actual machine. These reproducers control certain switch mechanisms, which I shall now proceed to describe.

Referring to Figs. 4 and 10, the side arm 48 carries a bracket on which an electromagnet I6 is mounted. The bracket 15 also supports a I spring arm 11 terminating in acatch 18 and carrying an armature 19. The arm 12 projecting rearwardiy from the bearing 58 of reproducer R. has a bevelled end '80 which normally engages the catch 18, as indicated bydotted lines 12' in Fig. 4. This locking engagement between the arm 12 and catch 18 holds the reproducer R suillciently elevated to keep the point of stylus 55 above the surface of record Ill, as indicated by the dotted outline 8| in Fig. 4. The stop 14 (see Fig. 10) is so adjusted that, when the bearing 58 is in its extreme right position on the supporting bar 5|, the arm 12 is in alignment with catch 18. The oppositely bevelled surfaces of these two members make it very easy to snap the arm into locking engagement with the catch, as may be seen in Fig. 4. When the electromagnet 16 is energized, the armature I9 is attracted and the catch I8 is drawn out of engagement with the reproducer arm 12, whereby the reproducer R drops into playing position on record l8. As previously explained, the stop 14 is so adjusted that the point of stylus 55 enters the circular starting groove ll of the record whenthe reproducer is released by the electromagnet 16. The casing of reproducer R. carries a movable switch arm 82, which is here shown as a substantially U-shaped spring blade grounded to the metal framework of the casing. The normal set or tension of spring arm 82 holds it 'away from the insulated contact 83, which is also .as the needle rides in the spiral groove l6, the

lower end 81 of the U-shaped arm 82 remains out of contact with the surface of .the record, so that the circuit of electromagnet 16' is open. When the end of spiral track I6 is reached and the needle 55 rides into the depression 86, the

rounded lower end 81 of the spring arm 82 engages the surface of the record, which is still rotating at the usual speed, as indicated by the arrow 88 in Fig. 8. When this occurs, the spring arm 82 is instantly moved against the contact 83 to close the circuit of electromagnet 16, which releases the reproducer R into playing position,

. conductors 92, 93 and I24 may represent grounded connections,

At the present time I prefer to hold the circuit of motor 4| open until just before the reproducer R of the first pair of records reaches the end of its travel. The circuit of motor M for the second pair of records is automatically closed through a suitable switch actuated by the arm 12 of reproducer R. The' details of this switch are shown in Fig. 11, which I shall now describe. The side arm 49 of the supporting bracket 40 has a pair of extensions 94 and 95 carrying sleeves 96 and 91, which may be slidably mounted. Each sleeve has a slot 98 cooperating with a set-screw 99 to hold the sleeve in adjusted position on its supporting member. The sleeve 91 carries an insulated contact I00 to which a conductor IN is connected. The sleeve 98 has a pin I02 on which two arms or levers I09 and I04 are pivoted for independent movement. The free end of arm I09 carries an insulated contact I04 to which a conductor I05 is connected. A contracting coil spring I06 is attached at I01 to the switch arm I03 and at I08 to the actuating lever I04. The sleeve 96 terminates in an extension I09, which carries a pair of stops H0 and H2. The spring I08 normally holds the arms I03 and I04 against the stops H0 and 2, respectively, whereby the switch contact I04 is in open position.

As the reproducer R. approaches the end of its travel on record I2, the arm '12 encounters the free end of lever I04 and gradually moves it toward the left (see Fig. 11) until the tension line of spring I00 crosses the axis of pivot pin I02, whereupon the tensioned spring snaps the pivoted switch arm I03 into closed position, as indicated by the dotted line I03. At the same time, the actuating lever I04 is thrown by the spring I06 into the dotted position 3' against the fixed stop II3 on sleeve 96. The engagement of switch contacts $00 and I04 closes the circuit of motor 4| through conductors H4, H5, H8 and Ill. The plug H3 is supposed to be inserted in a socket of the house-lighting circuit. The closing of the motor switch I00--I04' occurs before the stylus of reproducer R reaches the end of the spiral groove I6 on record l2, so that the second pair of records I0'-l2' is running at full speed when the associated reproducer R is dropped into playing position upon the energization of electromagnet 16'. It will thus be clear that the automatic circuit connections controlled by the movements offeproducer R first start the tumtables of thegnext pair of records I 0'I2' and then move the reproducer B. into playing posi-' tion as soon :1 the reproducer R reaches the end of the sound' groove in record I2. In this way, the second pair of records is automatically set in operation at the conclusion of the first pair of records, so that the reproduction is practicalh continuous from the time the reproducer It starts playing the first pair of records until the reproducer R is at the end of the second pair 0! records. The drop of the reproducers into playing position is very slight (see Fig. 4) being only a small fraction of an inch, so that no damage is done to the record. I

If it is desired to use more than two pairs of records, it is only necessary to have the reproducer B control a third pair of records and their associated reproducer in the same manner that the first reproducer controls the second reproducer, as above described. It is thus possible, in accordance with my invention, to construct an.

electric phonograph for automatically playing in succession any number of records without interruption, the reproducers being moved into playing position one after the other at the right moment.

The circuit of motor 4| in Fig. 7 is closed through a switch indicated as a whole by 9, which is mounted on the side arm 49' of the supporting bracket 48' associated with the second pair of records I0-I2'. The switch II9 may be considered a duplicate of the switch shown in. Fig. 11. The motor circuit can be traced from conductor I I6 through the closed switch I I9, con ductor I20, through the windings of motor 4|, and the return conductor II'I. After the reproducer R has reached its final position and the second pair of records I0'I2' has been set in operation, an attendant opens the switch 9 by merely throwing the pivoted lever I2l to the right. only explain that the lever I2I of switch 9 corresponds to the pivoted lever I04 in Fig. 11. When the switch I I9 is opened,- the turntables of records I0 and I2 stop, and the attendant may now put on a new pair of records and move the reproducer R to starting position against the stop 14. The reproducer R is placed in holding engagement with the associated catch 18, so as to be held out of contact with the new record I0, as previously explained in connection with Fig. 4.

When the second reproducer R approaches the end of its travel, the arm 12 on mounting 58 moves the switch lever I2I into closing position. precisely as described in connection with Fig. 11. The closing of switch I I9 starts the motor 4|. When the stylus 55 of reproducer R enters the terminal depression 86 in record I2, as explained in the description of Fig. 8, the switch arm 82 is actuated to close the circuit of electromagnet I6 through conductors 90, I22 and I28, through coil of electromagnet 16, and to the battery 89 through conductors I24 and 92. The energizing of electromagnet I6 permits the reproducer R to drop into playing position on the rotating record I0, so that the reproduction continues with substantially no interruption from the point where the reproducer R left off. After the new pair of records I0 and I2 have thus been set in operation, the attendant moves the switch lever I04- from the actuated position 3' (see Fig. 11) to its normal position to open the switch arm I09 and thereby. stop the turntables of records I0-I2. This gives the attendant an opportunity to change the second pair of records for a new pair on which the recording is supposed to be a continuation of the records played by the reproducer R. It is thus seen that one attendant can change the records in pairs, so as to make possible a continuous reproduction from any number of pairs of records. This apparatus is particularly useful for talking movies in which a long him of several reels is accompanied by synchronized music and speech.

To avoid unnecessary repetition, I need- When more than one pair of records are used, the records or the diflerent pairs and their respective turntables are provided with cooperating holes and pins to prevent the placing 01' a record on the wrongturntable. For example, the records l and I2 of the first pair have positioning holes 29 and 30, which make it impossible to place these records on any turntable except the ones for which they are intended. In like manner, the records l0 and I2 oi the second pair have holes 29' and 30 respectively, which fit only over pins on the second pair of turntables. As a further means of facilitating the correct positioning of the records, they may be identified by different colored labels. To give an illustration, the records intended for the first pair 0! turntables may have a red label in the center, while the records for the second pair of turntables may have a green label, and so on for other pairs of records. No

. special care is required to place the reproducers R 14 into correct position. Likewise, if the terminal grooves IQ of the second records of each pair should vary in diameter, the sleeve 96 may be adjusted to cause the arm 12 to close 'the motor circuit of the next pair of turntables at the proper moment. 'The position of sleeve 91 is adjustable to take care of any adjustments of sleeve 96.

Although I have shown and described certain specific constructions, I want it understood that my invention is not limited to the details set forth. I realize that changes and modifications will probably occur to those skilled in the art, because the basic features of my invention are susceptible of various embodiments without departing from the scope of the invention as defined in the following claims.

I claim as my invention:

1. A phonograph having means for supporting two disk records for simultaneous rotation in opposite directions, one of said records being played from the center toward the edge and the other record being played from the edge toward the center, a pickup mounted in operative relation to said records, and means whereby said pickup plays the records successively and substantially without interruption, said last-mentioned means including means enabling the pickup to travel automatically from one record to the next.

2. In a phonograph, the combination of two disk records having a substantially continuous pickup stylus from the sound groove of one rec- 0rd to that of the next.

4. In an electric phonograph, the combination of a disk record in which the spiral sound track terminates in a depression, the surface of said If the record being wholly of insulating material, an electric reproducer for said record, and a pair of normally open switch contacts carried by said reproducer, one of said contacts being so arranged as to be engaged by the insulated surface of the record and moved against the other contact when the stylus point of the pickup enters said depression.

5. In a phonograph, the combination of a pair of disk records having each a spiral sound track running to the very edge of the disk, and means for so mounting said disks that their spiral tracks unite at the edge.

6. In a phonograph, the combination of a pair of disk records mounted to rotate simultaneously in opposite directions and in contact at the edge,

' and interlocking means at the edges of said records to hold them inalignment.

'7. A phonograph having two turntables connected to rotate simultaneously in opposite directions at the same speed, a pair of disk records mounted on said turntables in predetermined relation to each other, one of said records having a spiral groove arranged to be played from the center toward the edge and the other record hav-'- ing a spiral groove arranged to be played from the edge toward the center, .and electric reproducing means controlled by said grooves.

8. In a phonograph, the combination of a pair of oppositely rotatingdisk records, one of which is played from the center toward the edge and the other is played from the edge toward the center, a separate turntable for supporting each record, means for rotating said records simultaneously in opposite directions, a reproducer operatively associated with said records, and means whereby the stylus of said reproducer automatically travels from the groove of one record to the groove of the I other. 4

9. In a phonograph, the combination of a pair of turntables connected to rotate simultaneously in opposite directions, a pair of disk records adapted to be mounted on said turntables, said records having each a spiral sound track running to the very edge of the disk, and cooperating means on said turntables and records for so mounting the latter that their spiral tracks unite at the edge.

10. In a phonograph, the combination of two disk records mounted in substantially the same plane to rotate simultaneously in opposite directions, said records being in contact at the edge and having spiral grooves united at the point 01. contact, whereby said united grooves form a substantially continuous stylus track from the center of one record to the center 01' the other, and a single reproducing means for playing botli records.

11. In a phonograph, the combination of two disk records mounted in substantially the same plane to rotate simultaneously in opposite directions, said records being in contact at the edge and having spiral grooves united at the point of contact, whereby said united grooves form a substantially continuous stylus track from the center of one record to the center of the other, and a reproducer so mounted that its stylus point travels in said track along a diametric line connecting the centers of said records.

12. A phonograph having means for supporting two disk records for simultaneous rotation in opposite directions, one of said records being played from the center toward the edge and the other record being played from the edge toward the center, a single reproducer for playing both.

records, means for mounting said reproducer so that it travels along a diametric line connecting the centers of said records, and means whereby the stylus of said reproducer automatically travels from one record to the other.

13. A phonograph having two turntables connected to rotate simultaneously in opposite directions at the same speed, a pair of disk records mounted on said turntables in predetermined relation to each other, one of said records being played from the center toward the edge and the other record being played from the edge toward the center, in combination with a single reproducer for playing both records, said predetermined relation of the records being such that the stylus point automatically travels from the groove of one record to the groove of the other.

14. An electric phonograph comprising at least two pairs of turntables adapted to support disk records, the records of each pair being in contact at the edge'and having a substantially continuous sound groove running from the center of one record to the center of the other, connection for driving each pair of turntables in opposite directions, an electric reproducer for playing the first pair of records, a second electric reproducer for playing the second pair of records,

means for holding the second pair of records and the associated-reproducer inoperative while the first reproducer is playing, and means operable when the first reproducer reaches the end of its sound groove for automatically placing the second pair of records and the associated reproducer in operative condition.

15. An electric phonograph comprising at least two pairs of turntables adapted to support disk records, the records of each pair being in contact at the edge and having a substantially continuous sound groove running from the center of one record to the center of the other, connections for driving each pair of turntables in opposite directions, an electric reproducer for playing the first pair of records, a second electric reproducer for playing the second pair of records, means for holding the second reproducer in an inoperative position while the first reproducer is playing, and means operable when the first reproducer reaches the end of its sound groove for automatically causing the second reproducer to move intoplaying position.

16. An electric phonograph comprising at least two pairs of turntables adapted to support disk records, the records of each pair being in contact at the edge and having a substantially continuous sound groove running from the center of one record to .the center of the other, an electric motor for driving each pair of turntables in opposite directions, an electric=. reproducer for playing the first pair of records, asecond electric reproducer for playing the second pair of records, means for holding the second reproducer in an inoperative position while the first reproducer is playing, means operable when the first reproducer reaches the end of its sound groove for automatically causing the second reproducer to move into playing position, a normally open switch for the electric motor of the second pair of turntables, and means whereby the first reproducer closes said switch to start the motor before the second reproducer is moved into playing position.

17.-In a phonograph, the combination of a record provided with an operative portion at the end of its sound groove,- and an electric reproducer carrying a fixed contact and a movable switch arm normally out of engagement with said contact, said switch arm being normally out of engagement with the record and movable into closing position by said operative portion of the record.

18. In a phonograph, the combination of a record provided with an operative portion at the end of its sound groove, and an electric reproducer carrying a fixed contact and a substantially U-shaped spring arm normally out of engagement with said contact, said switch arm being normally out of engagement with the record and movable into closing position by said operative por-' tion of the record.

19. A phonograph having a stationary support which carries a plurality of turntables for holding disk records in playing position, pickup mechanism for playing said records, an electric motor for simultaneously rotating said turntables and records, and means controlled by the position of said pickup mechanism for automatically opening the motor circuit when the last record is" played through.

20. In a phonograph, the combination of a pair of disk records supported for operative movement, the playing surfaces of said records being in substantiallythe same plane, and an electric reproducer mounted to travel in a rectilinear path from one record to the other, said reproducer beingso mounted that the path or the stylus is substantially in a line connecting the centers 01. said disk records.

21. A phonograph having a rod supported over the topboard, a bracket slidably and pivotaliy mounted on said rod, an electric reproducer carried by the front end of said bracket, a rear extension on said bracket, and a releasable latch supported independently of said reproducer and adapted to engage said extension for holding said reproducer out of playing contact with a record only when the reproducer is in a predetermined starting position.

22. A phonograph cabinet having a top-board, a plurality of turntables supported on shafts which extend through the topboard, an electric motor for rotating said shafts, electric pickup mechanism movably mounted in operative relation to records on said turntables, means whereby said mechanism plays said records in automatic sequence and substantially without interruption, and means for automatically opening the motor circuit when the last record is played through.

23. A phonograph having means for operatively supporting a record, a reproducer for playing said record, an electric switch mounted entirely on said reproducer and comprising a relatively fixed contact and a movable spring arm normally in open position and out of engagement with the record surface; which is formed with a depres-'O0 sion arranged to receive the stylus at the end of the sound groove, the entry of the stylus into said depression causing the reproducer to drop toward the record and carry said spring arm into engagement with the record, whereby the spring arm is automatically moved against said contact to close the switch, and an operative circuit controlled by said switch.

24. Acoustic apparatus comprising a turntable for supporting a disk record, an arm pivoted in-- termediate its ends for vertical movement and supported for horizontal sliding movement, a stylus-holding head mounted on one end oi said arm in operative relation to a record on said turntable, latching means arranged to engage the other end of said am for holding said head raised to keep the stylus out of contact with a record on 5 predetermined moment, whereupon the stylus descends to operative position on the record, said latching means holding the stylus out or contact with a record only when the stylus is in a predetermined starting position.

25. In electricrecording and reproducing apparatus, a stylus head carrying a pair of switch contacts, one of which is a substantially U-shaped spring arm adapted to be operated by engagement with a record,:and an operative circuit controlled by said contacts.

ADOLPH A. THOMAS.

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