Патент USA US2404784код для вставки
July 30, 1946. L. e; 'BOSTWICK 2,404,784 ’ ‘ACOUSTIC DEVICE Filed June 7,‘ 1940 a 3 Sheets-Sheet 2 h; . | INVENTOR L.G. BOSTW/CK BV MA-MhéM' A 7'7'ORNEY ' July 30, 1946. L_ G, BosTwlcK , 2,404,784 ACOUSTIC, DEVICE Filed June '7, 19,40 33:. // FIG6 7<-— +4 3 Sheets-Sheet 3 7 30 INVENT'OIR ' y L.G.BO$TW/C_K‘ aims/M AT Z'ORNE V ' 2,464,784 Patented July 30, 1946 UNITED STATES PATENT OFFICE 2,404,784 ACOUSTIC DEVICE Lee G. Bostwick, Chatham, N. 3., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application June 7, 1940, Serial No. 339,261 10 Claims. 1 This invention relates to electroacoustic trans (Cl. 177-386) 2 end; a ring-shaped permanent magnet l3 secured to ?ange I2 and a plate pole I4 attached to the magnet I3. Members I 2', I3 and I4 may be se cured together by welding or in any other suit able rmanner. The diaphragm I5, of bronze or other suitable material, has a ?ange I6 which is clamped between rings I7 and“ I8 secured to plate ducers suitable for underwater operation and more particularly to submarine sound receivers and transmitters. One object of this invention is to provide an electroacoustic transducer adapted for under water operation and having abroad and uniform pole I4 by fastening means such as screws I9. frequency range. A depending ?ange portion 20 of the diaphragm Another object of this invention is to provide a submarine type sound translating device, hav 10 supports the moving coil 2| in the annular air gap 22 between members I I and Ill. A ring 23' ing an electromechanical system, that is both e?i of ?exible material, e. g. rubber or they like, or cient and capable of withstanding high under metal, is secured to the diaphragm I5 interme water pressures. diate its center and ?ange I6. The outer’ portion One feature of this invention resides in a sub marine sound translating device having a vi 15 of ring 23 may be secured to a ring 25, as by ce menting. The ring 25', which may be of brass orv brating system of low effective mass and stiffness. other non-magnetic material, may be fastened to In accordance with another feature of this in plate pole I4 by means of screws 26. When the vention, the translating device has a resonant receiver is secured to the hull or skin 24 of the" frequency low enough to be critically damped by mechanical motional resistance and by simple 20 vessel, as by bolts ‘I0, the ring 23 is ?rmly clamped between the hull and’ring 25. damping means employing air or other gaseous That portion of diaphragm I5 lying between material. the ring 23 and the ?ange It may contain a plu A further feature of this invention involves the rality of ori?ces 2'! which maybe provided with use of a thin diaphragm and means for balancing the static and low frequency pressures on oppo 25 ?anges 28. Acoustic resistance material, such as felt or silk fabric 29, may be secured over the site sides thereof. ori?ces 21. The ?anges 28 may extend inwardly An additional feature of this invention resides as shown or outwardly, if desired. These flanges in a thin domed diaphragm of a diameter suffi 28 are to stiffen the diaphragm around the ori?ces cient to cooperate with an ef?cient magnetic sys tem, but having only a restricted portion of its 30 2i‘ and may be dispensed with where such stiffen ing is not necessary. The ori?ces, ?anges and re area subjected to water pressure, whereby the sistance material have been shown somewhat ex water impedance is maintained at a desired value. aggerated as to size in the interest of clarity of Other and further objects and features of this illustration. , invention will appear more clearly and, fully from the following description of illustrative embodi 35 On the concave side of the diaphragm I5 and secured to center pole‘ II is a member 30 which ments thereof taken in connection with the ap may be of brass or other non-magnetic material. The outer surface of member 80 conforms to the Fig. 1 is a sectional View of a receiver illustrat inner surface of the diaphragm and is spaced ing one embodiment of the invention; Fig. 2 is a section taken on lines 2—2 of Fig, 1; 40 slightly therefrom‘. Member 30 serves as a stop to prevent inward collapse of the diaphragm due Fig. 3 is a view partially in section of a receiver to extreme pressure or sudden surges caused by like that of Fig. 1 including means for equalizing waves, underwater explosions, etc. This member the pressures on opposite sides of the receiver pended drawings in which: diaphragm; Fig. 4 is an enlarged fractional view of the dia phragm showing details thereof; Fig. 5 is a section on line 5—5 of Fig, 4‘; and Figs. 6 to 11, inclusive, show respectively three modi?cations of a portion of the acoustic ele ments of the device. Referring now to the drawings, the receiver designated generally by reference character It comprises an annular magnetic structure and a domed diaphragm. The magnetic structure com prises a center pole H having a ?ange I2 at one 30 also is dimensioned to control the volume of 45 the chamber 3| behind the diaphragm in accord ance with desired acoustic characteristics. A plurality of ori?ces 32 in member 3!] connect the chamber 31 to a passage 33 in the center‘pole I I. Other means than the ori?ces 32 may be em played to afford communication between chamber 3| and passage 33. For example, a plurality of radial slots 'Ili may be formed in the bottom of member 33, before it is secured to- pole-piece II as shown in Figs. 6 and 7; member 30 may be spaced slightly from pole-piece I I and supported 3 4 on a plurality of studs or pins 12 as shown in Figs. 10 and 11 or by a notched or discontinuous ?ange ‘(I as shown in Figs. 8 and 9; or some suit able combination of the foregoing expedients may be used. on the other hand, are su?iciently attenuated to Portions of the ?exible ring 23, ring member 25, plate pole l4 and diaphragm I5, de?ne an prevent their equalization, allowing actuation of the diaphragm in response thereto. The chambers 34, 3|, 4| and the various pas sages interconnecting said chambers may be ?lled with a suitable ?uid, preferably gaseous mate rial, such as air or nitrogen. annular chamber 34 on the convex side of the dia When the diaphragm l5 vibrates, the ?uid in phragm. The chambers 3| and 34 may be con chambers 3| and 34 is forced back and forth nected through the acoustic resistance material 10 through the acoustic resistance means 29. By 29 covering ori?ces 21. employing air or a gas as the ?uid, mechanical The stiffness of ?ange it of the diaphragm may damping which is independent of temperature is be reduced by means of a plurality of overlapping thus afforded. The chambers 3| and 34 and the arcuate slots 36, as may be seen in the detail acoustic resistance material 29 are proportioned views of Figs. 2, 4 and 5. If it is desired to pre 15 to give the required damping effect at low fre vent leakage through slots 36, a thin membrane quencies near resonance. Venting of the dia 31 of suitable material, such as a cellulose plastic phragm through the ori?ces 21 reduces chamber may be secured, as by cementing, to ?ange I6 stiffness and permits a low resonant frequency. over said slots. This membrane 31 may be placed In a device of this type the diaphragm should on the under or back side of ?ange 16 as shown be big enough so that a suitable magnetic system is Fig. 5 or on the top or front side of said ?ange, may be associated therewith; but not so large if desired. In place of membrane 31 a plurality that the mechanical impedance of the water too of strips of plastic material may be employed one greatly exceeds that of the vibrating system, for each slot 36. If leakage through slots 36 is which would result in ine?icient conversion. indicated by the design requirements of the de 25 With the type of instrument disclosed, having a vice, they may be left open, or only partially cov low resonant frequency, the velocity ered as the situation demands. Connections may be made to coil 2| by suitable $2 means, such as ?exible conductors 5B, which may of the vibrating system at high frequencies will be be brought out through the clamping rings l1 and 30 determined by the mass reactances KB. of the I8. These conductors may be connected to leads water and X of the vibrating system as a whole, 51, which may be brought out through the ring respectively. Thus, 25, being sealed in to prevent leakage from the chamber 34. A ring or washer 35 of rubber or other suitable 35 E=m (1) material may be secured to center pole H and where plate pole 14, to close the inner end of the air-gap f=the force produced by the sound effective at 22. the diaphragm, The diaphragm may be protected from damage The force I‘ for a given sound water pressure is by submerged objects and the like, by means of a grid or screen 89. The member 60 may be se proportional to the diaphragm area or the square cured to the hull of the vessel by any suitable of its radius r; the reactance Xe is proportional means, such as screws or bolts 6! . to the cube of the diaphragm radius. Thus, The ori?ces 62 in the screen are made large enough so that they have no appreciable acoustic eifect on receiver * operation. In the sectional view, Fig. 2, which shows the For a given value of X there is an optimum value of r to obtain maximum velocity. Differen convex surface of the diaphragm IS, the resilient tiating Equation 2 with respect to r gives ring 23 has been omitted in order that details therebehind may be more clearly shown. The region of attachment of this ring to the dia phragm is shown by dot-dash lines on the dome portion of the diaphragm. Referring to Fig. 3, the passage 33 of the re ceiver i0 is connected by a tube 40 to a chamber 65 41. The chamber 4| may comprise a bellows 42 of bronze or the like, secured in a housing 43 Since by a cover 44. The bottom portion of housing 43 XR=K2T3 may be connected to the water outside of the ves sel by means of a pipe 45 suitably secured to the 60 hull at ori?ce 46 as by ?ange 41. The water mass then should be twice the mass The water pressure outside of the vessel is of the vibrating system to obtain maximum veloc transmitted to receiver chamber 3| and hence to ity. This desirable relationship can be realized the back of the diaphragm l5 via ori?ce 46, pipe with a light and e?icient vibrating system by re 45, interior of housing 43, bellows 42, chamber 4 I, 85 stricting the area of the diaphragm exposed to tube 40, passage 33, ori?ces 32 to chamber 3|. the water. Since the front of the diaphragm i5 is also sub The foregoing speci?c description has, for con jected to the Water pressure, the foregoing means venience, been restricted to a submarine sound provides for equalization of pressure on the op receiver. However, a transducer such as is con posite sides thereof. The impedances of the 70 templated by this invention may also be em tubes, pipes, chambers, etc., comprising the ployed as a submarine sound transmitter. When equalizing system, are such that it acts as a low used as a sound transmitter or radiator, the pass ?lter. The static pressure and low frequency damping resistance at the diaphragm ori?ces 27 should be made low, the diameter of said ori?ces pressures, such as are caused by waves, etc., are thus equalized. Pressures at sound frequencies, 75 large, and the volume of the chamber of the con 52,404,784 5 6 cave side of the diaphragm large as compared dome, and acoustic resistance means on said dia phragm and interconnecting the chambers. with a receiver. These changes will result in a lower resonance frequency above which the Ve locity of the diaphragm will Vary inversely with frequency and closely compensate for the quad ratic increase with frequency in the radiation or , 6. A submarine sound receiver comprising a is loading resistance of the water. Substantially uniform acoustic output will then result. Although speci?c embodiments of this inven tion have been shown and described, it will be 10 structure including ‘magnetic means having pole pieces de?ning an annular air-gap, a diaphragm of- non-magnetic material and having a thin, con vex portion, a resilient peripheral‘ ?ange, and a depending ?ange, a sound current coil mounted on said depending ?ange, said peripheral ?ange secured to a pole-piece to position the coil in the air-gap, said diaphragm and structure de?ning a chamber, and a ring of resilient material secured at its inner edge to the convex side of the dia understood that modi?cations may be made therein without departing from the scope and spirit thereof as de?ned by the appended claims. What is claimed is: phragm intermediate the center and the periph 1. A submarine sound receiver comprising a 15 eral ?ange and having its outer portion secured structure including magnet means, a domed dia to said structure, a portion each of said ring, phragm attached to said structure, an electrical diaphragm and structure de?ning a second cham current conductor secured to the diaphragm and ber, said portion of the diaphragm having acous located in the ?eld of said magnet means, stop tically resistant ori?ces connecting the two cham means secured to said structure and spaced from 20 bers. the inner surface of the diaphragm to de?ne 7. A submarine sound receiver comprising a structure including magnetic means having a therewith a chamber, ?exible means secured to the outer surface of the diaphragm to restrict the center pole, and a plate pole spaced therefrom to area thereof subjected to exterior pressure, said ?exible means, diaphragm and structure de?ning a second chamber, and acoustic resistance means, associated with the diaphragm and connecting the two chambers. de?ne an annular air-gap, a diaphragm of non magnetic material having. a thin, central dome portion and a resilient supporting ?ange secured ' to said plate pole, a sound current coil secured to the diaphragm and positioned in the air-gap, 2. An acoustic transducer comprising a struc a stop member secured to the center pole and ture including means for producing a magnetic 30 having its outer surface conforming to the inner ?eld, a domed diaphragm secured to said struc surface of the diaphragm dome and spaced slight ture and de?ning therewith an acoustic chamber, ly therefrom to de?ne a chamber, a resilient ring an electrical current conductor attached to the attached to the structure and secured to the ex diaphragm and positioned in said ?eld and re terior surface of the diaphragm dome interme silient means secured to said structure and dia diate its center and edge to restrict the area phragm for restricting the area of the diaphragm thereof in contact with water pressure, a portion , subjected to sound pressure, a portion of the re each of the resilient ring, the diaphragm and the silient means and the diaphragm de?ning with structure de?ning a second chamber, and acoustic ‘ resistance means associated with ori?ces in said said structure a second acoustic chamber, said diaphragm having acoustic resistance ori?ces diaphragm, and connecting said chambers. therein connecting the two acoustic chambers. 8. A submarine sound receiver comprising a 3. An acoustic device for operation in a sound magnet structure including a pole-piece, an out transmitting medium more dense than air, com wardly convex diaphragm of thin non-magnetic prising a structure including magnetic ?eld pro material having an electrical current conductor ducing means, a non-magnetic diaphragm having secured thereto in cooperative relation to said ' a stiff, convex central portion and a resilient outer 45 pole-piece, resilient means secured to said dia portion connected to said structure, a sound cur phragm and associated with said structure to con rent coil secured to the diaphragm in cooperative ?ne a restricted portion of said diaphragm to ex relation with the magnetic field producing means, ternal pressure and to de?ne with said diaphragm means for restricting the area of the diaphragm and structure a chamber on one side of said dia subjected to the pressure of the sound transmit 50 phragm, a chamber on the other side of the dia ting medium, acoustic impedance chambers on phragm, and acoustic resistance means connect opposite sides of the diaphragm, said restricting ing said chambers together through said dia phragm. ' means cooperating with a portion of the dia phragm to de?ne one of said impedance cham 9. A submarine sound receiver comprising a bers, and acoustic resistance means secured to 55 structure including magnetic means having a cen the diaphragm and connecting the impedance ter pole, and a plate pole spaced therefrom to de chambers. 4. An acoustic device for underwater operation comprising a structure, an outwardly convex, ?ne an annular air-gap, a diaphragm of thin non magnetic metal having a central, outwardly con vex dome portion and a resilient supporting domed diaphragm cooperating with said structure 60 flange portion secured to said plate pole, a sound current coil secured to the diaphragm and posi to de?ne a chamber, means in front of said dia phragm for restricting water pressure to a por tioned in the air-gap, an outwardly convex stop tion thereof, said means cooperating with the member secured to said center pole, spaced from structure and diaphragm to de?ne another cham the dome portion of the diaphragm and de?ning ber, and means de?ning restricted passages be 65 therewith a chamber, a ring of rubber-like ma tween said chambers. terial secured to said structure and to the convex 5. -.A submarine sound translating device com side of the diaphragm, intermediate the center prising a structure, an outwardly convex, domed and the supporting ?ange thereof, to limit a por diaphragm resiliently attached to said structure tion only of the diaphragm dome to external pres and de?ning with said structure a chamber, a 70 sure, a portion each of the ring, the structure and resilient ring secured to the convex surface of the the diaphragm de?ning a second chamber, behind diaphragm dome and to the structure for con said ring and outside of the diaphragm, the por ?ning water pressure to a restricted portion of tion of the diaphragm between the ring and ?ange the diaphragm, a second chamber behind said containing perforations through which said resilient means and outside of the diaphragm 75 chambers are interconnected, and acoustic re 2,404,784 8 sistance material secured to the diaphragm over diaphragm dome and to the structure for con said perforations. ?ning water pressure to a restricted portion of the diaphragm, a second chamber behind said ?exible means and outside of the diaphragm dome, and means including acoustic resistance 10. A submarine sound translating device com_ prising a structure, an outwardly convex, domed diaphragm resiliently attached to said structure and de?ning with said structure a chamber, ?ex ible means secured to the convex surface of the interconnecting said chambers. LEE G. BOSTiWICK.