US1897722A

US1897722A - Sound recording and reproducing means

Info

Publication number: US1897722A
Application number: US533711A
Authority: US
Inventors: Dahmen Karl
Original assignee: Individual
Current assignee: Individual
Priority date: 1929-03-30
Filing date: 1931-04-29
Publication date: 1933-02-14
Anticipated expiration: 1950-02-14

Description

Feb. 14, 1933. K DAHMEN I 1,897,722

SOUND RECORDING AND REPRODUCING MEANS Filed April 29,1951

Fig.4.. f as 4O a g 3 35 4 41 Jnveni'or: (4R4 Dal /M5 A'Hornoys Patented Feb. 14,1933

UNITED STATES: PATENT OFFICE:

KARL DARREN, Ol DUSSELDOBF, GERMANY SOUND RECORDING AN REPRODUCING HEARS I Application filed April 29, 198i, Serial No.

This invention has reference to a method of recording acoustic signals by electro-mag netic means and it is one of the important objects of the invention to produce acom paratively large or extensive record in a very simple manner upon a com aratlvely small carrier, 8. plurahty of suc records being superimposed upon each other in the well known manner. With the methods heretofore in use for the production of acoustic records there was the inconvenience that the tion or of spacing the coils for each record,. 2 so that the number of the records to be superimposed had to be restricted from constructional reasons.

N ow with the method of the invention to be described it becomes possible however to 'arrange an almost unlimited number of records in a comparatively small space. Broadly considered, this object is accomplished by producing two records of each acoustic signal simultaneously the intensity of which varies however in accordance with a certain freuency. Furthermore, the intensity curves of tr e two records are displaced with relation,

to each other by a differentiated positioning of their periods, so that for each phase the sum of each two recording intensities of equal time-periods remains the same, that is to say,

' that the resulting intensity is constant. For

each of the superimposed records a different frequency of the fluctuations of intensity is $5 to be selected, while the velocity of the recording carrier relatively to the record producing member remains constant.

The invention will be more fully described bly reference to the accompanying drawing s owing an exemplification embodying the wheels 538,711, and in Germanylarch 80, 1929. I

principles of this invention in perspective view, all the details of the supporting frame and of the means which do not constitute a part of the invention, and are unnecessary for the understanding thereof not having been shown in the drawing.

In the drawing: r

Fig. 1 shows diagrammatically a sound recording and reproducing device.

Fig. 2 1s a perspective view of a part of the device. The modification shownin the drawing comprises two previously magnetized steel bands 1 situated side by side and wound on rollers 23, one of whichis shown in Fig. 1 The bands 1 pass over a" guide 1-oller 2 and are wound on rollers 24. The

rollers

23 and 24 are rotated by means of

electrical motors

25 and 26 which are connected with a main 31 .by conduits 27 and'28, while the

wirings

29 and 30 connect said motors with a return line 32. A switch 33, 34 is used to connect either the motor 25 or the motor 26 with a source of electrical energy not shown in the drawing, one of the motors being cut off from the supply of electricalcurrent while the othermotor is in operation. In the position shown in Fig. 1 the

main lines

31 and 32 are connected with the motor 26 .drivingthe. rollers 24.so

that the bands 1 will be moved in the direction of the arrows shown in Figs 1 and '2, and will be wound on said rollers 24. By switching the switch 33, 34 to its other position, shown'by dotted lines in Fig. 1, it ispossible to wind the bands 1 back on the rollers 23. A wire 35 connects the main line 31 with

resistances

36 and 37, which can be regulated by

levers

38 and 39. Conduits 40 and 41 connect the

resistances

36 and 37 with electrical motors 42 and43. which are. con nected with the return line 32'by means of M 'the conduit 44. -The electrical motor 42 drives a shaft 7 by means of a cord 45 passing around a grooved wheel 8 rigidly connected with said shaft. Two

cords

46 and 47 connect the electrical motor 43 with grooved 17 and 18 and drive the

adjustable resistances

13 and 14 connected with said wheels. Two

coils

3 and 4 are situated over the bands 1 at the placewhere these bands pass over the roller 2, said coils. being conactuate the

arms

5 and 6, so that the

magnets

11 and 12 connected with the

arms

5 and 6, and situated within the

coils

3 and 4, alternately. approach and recede from the bands ,1. Itis to be notedth at the

magnets

11 and 12 should have a polarlty different from that of the bands 1. A sliding contact 15 is situated over the adjustable resistance 13 driven by a wheel 17 and forms an angle of 180 with a sliding contact 16 situated over the ad- 15 justable resistance 14, which is driven by the wheel 18. The

resistances

13 and 14 are connected with the lower ends of the

coils

3 and 4 by means of

wires

19 and 20, while the upper ends of the

coils

3 and 4 arevconnected with one of the leads 21 of the talking circuit. The other lead 22 is connected with the

sliding contacts

15 and 16.

During the reception of the acoustic signals the

sliding contacts

15, 16 are uniformly rotated, so that due to the

resistances

13 and 14, a weaker or a stronger current impulse will be produced in the coil 3-and then in the coil 4, so that either one or the other of the bands 1 will be submitted to a stronger or a weaker action of the magnets, while the total intensity of the magnetic influence remains always the same. At the same time,

however, said

magnets

3 and 4 are alternatingly moved by the cams 9, 10, so that they will come closer or less close to their corre-' sponding steel bands 1. The bands 1 are provided with records of sounds along their entire length while being wound on the rollers 24. Then the position of the switch 33, 34 is changed and the bands 1 are again wound on the rollers 23. The recording which takes place during this second winding is superimposed on the previous records, so that said subsequentrecording must take place with a frequency different from that of the previous records. changing the position of the

levers

38 and 39 of the

resistances

36 and 37, since it will correspondingly change the velocity of rotation of the

sliding contacts

15 and 16 and of the cams 9 and 18. By a suitable selection of the rotating speed of the

sliding contacts

15, 16 and of the cams 9, 10 there is the possibility for the production of a'large number of different frequencies, and consequently of a larger number of records to be superimposed. The reproduction of such records should, of course, take place under the same operating conditions. 1

It should be understood that the invention is not limited to the embodiment herein shown and described merely by way of exemplification, and other means may be used for the production of the modulating frequencies, as long as the essential features of This is easily obtained by the invention remain unchanged which are constltuted by the fact that several records may be obtained by different frequencies upon. the same carrier, which are then reproduced under the same conditions.

I claim:

'1. A method of recording acoustic signals, comprising the steps of producing two records for each acoustic signal, each of said records havlng a time period and intensity different from that of the other record produced by the same signal, the sum of the intensities of two records produced by the same signal having a constant value, and superlmposlng records having a different frequency of fluctuations of intensity.

2. A method of recording acoustic signals,

comprising the steps of producing by"electro-magnetic means two records for each acoustic signal on a recording element, passing phase displaced electrical currents through said electro-magnetie means during the recording of said acoustic signal, and then superimposing records having a different frequency from that of the first-mentioned records on said recording element.

3. A device for recording acoustic signals, comprising a pair of magnetized bands, means for synchronously movingsaid bands, a pa r of electro-magnets situated near said bands, means for alternately reciprocating said magnets, a talking circuit connected with said magnets, resistances connected with said magnets, and means for producing a phase diiierence'in one of said resistances.

4. A device for recording acoustic signals, comprising a pair of magnetized band's,

means for synchronously moving said bands,

a pair of electro-magnets situated near said bands, means for connecting said magnets in parallel, means for alternately reciprocating said magnets, a talking circuit connected with said magnets, a pair of resistances, means for connecting said resistances in parallel with said talkingcircuit, one of said resistances having a phase displacement of 180 degrees with respect to the other resistance, and means for operating such resistances.

In testimony whereof I aflix my signature.

KARL DAHMEN.