US1640538A - Sound apparatus - Google Patents

Description

mwm 399 Egg? A. DU BOiS-FZEYMOND S-OUND APPARATUS Filed March 24. 1921 Patented Aug. 30, 1927.

UNITED STATES 1,640,538 PATENT OFFICE.

ALABD DU BOIS-REYMOND OF PLON', NEAR KEL, PRUSSIA, GERMANY, ASSIGNOB TO THE FIRM SIGNAL GESELLSGHAFT M. B. 3., 01 KIEL, GERMANY.

SOUND APPARATUS.

Application filed March 24, 1921, Serial No. 455,321, and in Germany.August 6, 1917.

In the construction of electromagnetically driven or operating sound apparatus, for example, electromagnetic submarine sound transmitters or receivers, the necessity often arises of fastening current coils of various kinds on the oscillating structures or systems of the apparatus. The invention is based on the recognition of the fact that the simple fastening of the coils on the oscillating structures or systems is unsatisfactory, in

that the wires surrounded with insulating material form a loosefstructure in the acoustic sense which strongly damps the oscilla tory system. Furthermore it is not feasible devised and will be hereinafter described in detail. The technical carrying out of the invention can be eifected in different ways; either by building the coils themselves, and the oscillatory structures carrying them, together as a rigid mass, or by choosing a method of fastening the coils which obviates an acoustically injurious action of the same on the oscillatory structure. In the first case in the design of the oscillatory structitre the additionalmass formed b the coil must be taken into consideration. ther and further objects of the invention will appear or be pointed out hereinafter.

The rigid fastening above referred to is efiected, for example, by casting the coil parts with binding material (resin, bakelite, or the like) so as to form a rigid structure,

and then casting with suitab e matrix drilled grooves, slots or the like.

Suitable means for mounting the coils on the oscillatory structure or for mounting the ,coil carriers on the oscillatory structure for the purpose of acoustically insulating these parts may be effected by the interposition of non-rigid fastening means or intermediate layers with no appreciable elastic action or of such a nature as to form a structure tuned so low as to have a natural frequency much below the natural or coupling frequencies of the oscillatory structure or system. Thus, for exam le, the coils (to be hereinafter referred to? may be surrounded by or encased in such materials as rubber,

.structed in accordance with the of my invention and in which the interstices between the windings are filled in with suitable material for binding them together. The coil is thus cast in.

Figure 2 shows in section an electro-magnetic sound apparatus with a choking coll attached to, the electromagnet system by springs. 1

Figure 3 shows in modified form an axial section at right angles to Figure 2 disclosing in detail the method of supporting the 4 coil 5.

In Figure 1, 1 indicates a sound diaphragm, 2 and 3 the armature and electroma et of an electromagnetically operatin oscillatory structure, and 4 sprin s by whic the parts 2 and 3 are connecte with one another. 5 is the exciting coil which lies in slotsin the field magnet 3 and is cast therein by means of an embedding mass 6.

According to the embodiment of my in-, yention shown in Figures 2 and 3, an auxiliary ap aratus may, when necessary, be mounte upon the vibratory structure without causing in 'urious damping eflects. Thus, a choking coi 7 with a laminated iron core 8 is held by the carrier 9. The latter is ided on me 10 which'are rigidl seated in the principles with the'iron' core carried by it engages against the carrier itself through soft layers 12 of indiarubber or the like. The excitin coils 5 of the electro-magnet are here (11- vided into an alternating current coil and a direct current coil, and in the current circuit of the latter the choking coil is connected.

The purpose of this construction will be readily understood. By an inspection of Figures 2 and 3, it will e seen that the construction is simllar to that in a transformer having a closed magnetic circuit. In come are obtained when the number of turns vin the direct current winding is made about ten times as great as the number of turns in the.

alternating current winding. Such a ratio in the numbers of turns in these windings, how-.

ever produces an alternating current potential 111 the direct current coil ten times as large as that in the alternating current coil and thus occasions a new difliculty. To overcome this difliculty, the choking coil? is connected up in circuit with the direct current winding for the purpose of confining the high Voltages to those conductors which are disposed entirely within the casing 13. This is shown in Fig ure 2 where the Wire 20 goes from the choke coil 7 to the winding 5 while the wire 21 connected to the other end of the winding 5 passes through the casing. The other lead 22 connects directly to the choke coil 7 so that the choke coil 7 and the direct current winding 5 are in series. 'As a result, the question of insulationas related to those wires which pass into and out of the casing becomes a comparatively simple one.

Another feature of the construction of Figures 2 and 3 is that all the operating parts are contained within a casing, a portion of the wall of which is formed by the dia hragm 1 and another portion of the wall of which is formed by the removable or detachable cap 13, and that these arts are carried or supported by the diap ragm 1 free from the cap 1. This feature of construction makes it possible to remove the cap without disturbing interior connections, so that ins ection of the operating parts may readily had.

I claim: a

1. In acoustic apparatus, in combination, a vibrato diaphragm, a vibratory structure carried y sa1d diaphragm, an electric coil, and means whereby said coil is carriedby sa'idvibratory structure but is acoustically insulated therefrom.

2. In acoustic apparatus, in combination, a vibratory diaphragm, 'avibratory structure in the form of an electro-magnet carried by sa1d dlaphragm, an electric coil, and means whereby said coil is carried by said elcctro magnet but is acoustically insulated therefrom.

3. In acoustic apparatus, in combination, a vibratory diaphragm, a vibratory structure in the form ofan electro-magnet carried by said diaphragm, a direct current polarizing coil for said electro-magnet, an alternating current exciting coilfor said electromagnet, a choke coil for'said polarizing coil circuit,'and means whereby said choke coil is carried by said electro-magnet but is ac'oustically insulated therefrom.

4. In acoustic apparatus, in combination, a vibratory diaphragm, a vibratory structure carried by said diaphragm, an electric coil, and means supporting said coil on said vibratory structure, sa-id meansbeing of such resiliency asto acoustically insulate the coil from said vibratory structure.

5. In acoustic apparatus, in combination, a vibratory diaphragm, a vibratory structure carried by said diaphragm, an electric coil,

and means SHPPOIlJlIl said coil on said vibratory structure, sai means having a natural frequency considerably below that executed by said vibratory structure, whereby the coil is acoustically insulated from said vibratory structure. i

6. In acoustic apparatus, in combination, a casing, a vibratory diaphragm forming a portion of the wall of said casing, 21 removable cap forming the remaining portion of the Wall of said casing and completely closing the apparatus, a vibratory structure carried by said diaphragm, an electric coil, and means whereby said coil is carried by said vibratory structure but is acoustically insulated therefrom; the said vibratory structure and coil being supported by said diaphragm free from the removable cap of said casing.

7. In acoustic apparatus, in combination, a casing, a vibratory diaphragm forming a portion of the wall of said casing, a removable cap forming the remaining portion of the wall of said casing and con'ipletely closing the up )aratus, a vibratory structure in the form 0 an electro-magnet carried by said diaphragm, a direct current polarizing coil for said electro-magnet, an alternating current exciting coil. for said electro-magnet, a choke coil for said polarizing coil circuit, and means whereby said'choke coil is carried by said electro-magnet but is acoustically insulated therefrom; the said electromagnet and coils being supported by said diaphragm free from the removable cap of said casing.

In test-imonywhereof I afl'ix my signature.

ALARD DU BOIS-REYMOND.

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