Den 3, 1946. 1.. G. BOSTWICK ETAL 2,411,365 SUBMARINE SIGNALING DEVICE Filed Feb. '10, 1944 _ 6 Shee_ts-Sheet 1 22 60 98 I02 .99 ' __ L. G. BOSTW/C‘K 1 INVENTORS @ ®® > J_ H K/NG BY 04% a. 1M ATTORNEY Dec. 3, 1946. ’ |_. e. BOSTWICK ET AL 2,411,355 SUBMARINE SIGNALING DEVICE Filed Feb. 10, 1944 ‘ 6 Sheets-Sheet 2 22' LGBOSWCK '"ZENWS J; H; KING Y 94m 6. v} ATTORNEY ‘ Dec. 3, 1946. _ 1.. G. BOSTWICK ETAL ‘ 2,411,365 SUBMARINE SIGNALING DEVICE Filed Feb. 10, 1944 6 Sheets-Sheet 3 Dec._ 3,1946. L. e. BQSTWICK 'ETAL 2,411,865 SUBMARINE SIGNALING’ DEVICE Filed Feb. 10, 1944 I 6 Sheets-Sheet 4 60 ' L. a. BOSTW/CK ATTORNEY ' me. 3, 1946. i... G. BOSTWICK ETAL. 2,41 1,865 SUBMARINE SIGNALING DEVICE Filed Feb. 10, 1944 _ 6 Sheets-Sheet 6 FIG. 8 2/ G. BOSTW/CK wvEivToRs 1.. J. H KING 5' V A T TOR/V5 r" Patented 3, ‘2,411,865 Lee G. Bostwick and Jo . . 5., ,-». E. ‘is-1. g, Cbatham, 1 gnors to Bell Telephone Laboratorlw, Incorporated, New York, N. Y” a coratlon or New York it, ran, SerialNc. 521,782 (91. 177-388) 1 phragm due to variations in the hydrostatic pres— sure thereon but is not actuated in response to vibrations of the diaphragm at frequencies within the operating range of the signaling device. In accordance with a further andlvspeci?c fea This invention relates to submarine signaling devices and more particularly to high power projectors of the direct radiating diaphragm type especially suitable ‘for the propagation of low _ frequency signals. ture of this invention, thelinkage between the. The attainment of high'iptensity signals in a submarine signaling device or the diaphragm type entails, inter alia, the use of a diaphragm 0! sub-_ '. stantial area and capable oi large amplitude vibrations. In addition, in devices operable at diaphragm and the microswitch includes a me-' chanical ?lter element of such. parameters that the microswitch will be actuated only, in response’ to displacements of the diaphragm at frequencies below the lowest frequency in the range the sig low frequencies, the diaphragm must have a sup‘ \ naling device is intended to translate‘. porting or suspension system oflow stiffness in In one and particularly advantageous construc order to place the fundamental resonance fre tion, the ?lter element comprises a spring integral quency of the vibrating system low in the fre quency range. As a result; when such a device is 15 with the diaphragm and coupled toga mechanical resistance defined by a. paddle member cscil- v submerged, and particularly when it is submerged latable in a body of highly viscous liquid. to considerable depth, large amplitude displace The invention and the above-noted and other I ments of the diaphragm may occur due to the features thereof will be understood more clearly hydrostatic pressure upon the diaphragm. Such displacements would deleteriously affect the oper 20 and fully from the following detailed description‘ with reference to the accompanying drawings in ation of the device and might result in damage to the diaphragm and the supporting or suspen Fig. l is a perspective view of a submarine sis= sion system therefor. which: ' " ' ‘ naling device illustrative of one embodiment of' ' One object of this invention is to substantially prevent net displacement of the diaphragm» of a submarine signaling device due to hydrostatic. pressures while allowing large amplitude vibra this‘ invention; ' Fig. 2 is a side view mainly in section‘ of the‘ signaling device shown in Fig. 1; Fig. 3 is a rear view of the device shown in Figs. 1 and 2, aportion' of the back of‘ the hous forces applied thereto.. More speci?cally, one object of this invention is to compensate ac 30 ing and a part of the reservoir being removedi tions of the diaphragm in accordance with signal _ > curately and quicklyfor variations in hydro static pressures acting upon the diaphragm of a submarine signaling device, to maintain the dia . phargm in its normal neutral position} In accordance with one feature of this inven Fig. '4 is a detail view in section along plane 5-5 of Fig. 3; ' Y ' tion, a submarine signaling .device comprising a impedance element included in this system being diaphragm having one surface in communication with the sea and the opposite surface enclosed broken away to show details of construction: Fig. 7 is a side view mainly in section of a sub by a housing, is provided with a chamber or reser marine signaling device illustrative o‘i another embodiment of this invention; means actuated by the diaphragm for releasing Fig; 3 is a rear view of the device shown in gas from the chamber into the housing or from Fig‘? with a portion of vthe ‘housing removed; the housing into the sea‘to maintain equality between the pressures acting upon the opposite - surfaces of the diaphragm.‘ In accordance with anothervfeature of this in- ’ operated valve coupling the chamber to the inte-3 rior. of the housing and a microswitch for con trolling the energizing circuit for the solenoid ‘of the valve, and a mechanical linkage between the diaphragm and the actuating element of the microswitch is provided, the linkage being con structed and arranged so that the switch is oper ated in response to displacements of the dia ' Fig. 6 is a top view of the impedance element; voir containing a gas under pressure ‘and with vention, the aforesaid means includes a solenoid ' Fig. 5 is a detail perspective view of the sole noid operated valve and the actuating system for 35 the switch therefor. a portion of the mechanical “ ~ and - Fig. 9 is a perspective view of the control sys team for the valves in the‘ device illustrated in I Figs. '3 and 8. I - , . Referring now to the drawings, the submarine signaling device illustrated in Figs. 1 to 6 in’ elusive comprises a rugged housing 20, for example ~ cast of-metal, provided with mounting lugs ti and having ‘secured in ?uid-tight relation'to the front end thereof, as by a plurality. of bolts 22, an annular face plate 23 which mounts a signal traiatpa‘ unit. ‘This unit, which advantage-7 2,411,885 ously is of 'the' moving coil type as shown in Fig. 2, comprises a magnet assembly including coaxial pole-pieces 24 and 25 de?ning an annular gap .26. The pole-pieces are clamped against opposite ends of a cylindrical permanent magnet 21 by screws 28 and are maintained in accurate coaxial relation by a‘ non-magnetic spacer ring 29. 4 tuating element 55 therefor is supported by'a rigid bracket 58 secured to the housing 2|). Electrical connection to the solenoid is established by way of a cable 51. The construction is such that nor mally, ‘that is, when the solenoid is deenergized, the valve is closed, ‘and when the solenoid is ener gized, the valve is opened and gas from the cham ber 49 ?ows into the housing 20. a . Secured to the poleepiece 25, as by houses, The solenoid energizing circuit includes a mi is a shallow, apertured, dished, non-magnetic 10 croswitch 58, shown in Figs. 4 and 6, which is frame 3| which is secured also vtothe face plate mounted on a supporting strip 59 and is actuated 23 as by bolts 32. An annular diaphragm, for by a linkage extending from the diaphragm, il example of metal such as beryllium copper, in lustrated in Figs. '4, 5 and 6. As shown most cludes an intermediate concavo-convex portion clearly in Fig. 5, the outer '?exible portion 35 33 and irmer and outer portions 34 and 35, re 15 of the diaphragm includes a ?nger or spring spectively, of sufficient ?exibility to allow free member 60 to which a drive pin 8| is a?ixed, the vibration of the intermediate portion 33 as a pin extending through but ‘not touching an aper whole analogous to a piston. The peripheral part ture reducing bushing 90 a?lxed to the frame of the outer portion 35 is clamped to the frame 3|, and into engagement with‘ the actuating ele 3| 'by a ring 36 and the inner edge part of the 20 mentof the microswitch 88. Associated with the inner ?exible portion 34 is clamped against a drive pin BI is a mechanical resistance element pnotuberance 31 on the pole-piece 24 by ‘a non which comprises a casing 62 having mounting magnetic ring 38. .Thediaphragm has a?ixed arms 63 which are secured to the frame 3| and thereto a cylindrical mount 39, for example of face plate 23 by bolts 64. The casing .is partially insulating material, such as phenol'fabric, which ~ ?lled with a highly viscous ?uid, for example an extends into the gap 26 and carries a. driving coil 40. - on known commercially as “Vistac,” and has af ‘ fixed thereto by a cap 65 a resilient sealing mem Over-lying the diaphragm and secured in inti ber 66, for example of neoprene. Immersed in the ?uid ?lling is a cylindrical paddle member 61‘ which is supported by‘a rocker element 68 having an arm 69 provided with an aperture ‘i0 of which is- clamped between the face plate 23 through which the drive pin 6| extends. The and the ring 36 and the central portion of which arm 69 has threaded thereinto a pair of aligned is clamped against the ring 38 by a‘ non-magnetic cone pivots 1| engaging the drive pin 6|. The stud 42 ?xed in position by a bolt 43. The dia rocker element 68 has threaded thereinto a pair phragm 4| serves as a sound barrier at‘ frequene of cone pivots 12, which are aligned 'and'posi cies up to several hundred cycles per second and tioned substantially in the plane of the sealing has a ?uted portion |||l therein to ‘increase its member 66 so that the stiffness reaction of the ?exibility. , member 66 is minimized andhigh sensitivity com Electrical connection to the coil 40 and we 40 pensation is ‘obtained. Motion of the paddle 'microswitch described hereinafter may be “es member 61 through the viscous ?uid develops a tablished by way of a cable, a portion of which is ' high mechanical resistance, as is apparent. --shown at 44 in Fig. 2, which enters the housing The casing 62 is provided with an arm." to . mate engagement with the intermediate portion 33 thereof is a protective membrane or diaphragm 4|, for example of gum rubber, the peripheral part 20 through a suitable‘ water-tight stu?ing box 45. ' When the submarine signaling device is sub merged, the diaphragm 33 is subjected to hydro static pressures which might deleteriously affect the operating characteristics of the device and which might be of such magnitude, particularly when the device is utilized at great depths, as 58 is secured by screws 14. The mechanical resistance element and the spring arm 60 are constructed and arranged so that the rod 6| moves in response to even small changes in the hydrostatic pressure effective up on the diaphragm but remains substantially sta- ‘ to distort or even destroy the diaphragm. In ac tionary when the diaphragm vibrates in response. to signal currents supplied to the driving coil cordance with a feature of this invention, means are provided for counteracting the hydrostatic pressure upon the diaphragm to maintain the steady pressures effective upon the two faces of the diaphragm in equilibrium. As shown in Fig. 2, the housing is provided with a substantially hemispherical wall 46, which may be cast integrally with the housing, and a cover member having a substantially hemispherical Wall 41 concentric with the wall 46 is secured in ?uid tight relation to the rear of the housing, as by which the mounting stripv 58 for the microswitch therefor. ' The principles involved will be under stood from the following considerations. The rod 6| is moved in response to. displace-' ment or motion of the diaphragm, the motion or displacement of ‘the diaphragm being communi cated'to the rod by way of the spring arm 60. This arm, viewed as a mechanical impedance ele 60 ment,'is essential‘y a, stiffness. bolts 48. The two walls 46 and 41 bound a fluid- = Associated with the rod and arm is the resistance element which constitutes a resistance in parallel with the sti?- I ness noted. The stiffness and resistance de?ne a tight chamber or reservoir 49 into which gas, mechanical ?lter so that, as will beapparent, the ‘such as air, under substantial pressure may be motion of the rod 6| as afunction- of frequency introduced through a valve 50 and from which will be dependent upon the constants of the filter. gas may escape into the housing 20 by way of a These constants may be correlated to effect dis- _' port 5| in the wall 46. Threaded into the port criminatlon against a desired range of freq'u'ene 5| is a coupler member 52 through which com cies. Speci?cally, in a device of the construc munication is established from the chamber 49 70 tion described, the parameters involved are cor to one side of a solenoid operated valve 53 of con-I related so that the ?lter discriminates against , ventional construction, the valve having a re stricted outlet coupling 54, shown in Fig. 3, in communication with the interior of the housing 20. The valve,‘ together with the solenoid @0 frequencies-in the intended operating range of. the device, whereby the rod 6| is moved in re sponse to steady displacement of the diaphragm or vibration thereof below the operating range, , - aera'ece but motion of the rod is prevented in this range. realized. Attainment of high power capacity re- ' quires the use of a fairly large diaphragm,large In a particular ‘device of the construction .de scribed hereinabove and intended to operate most 'emcientiy in the range from 20 to 350 cycles per vibrational amplitudes and a driving coil ca- _ pable of dissipating the heat generated therein resistance average, was approximately 15x 10*3 when signal currents requisite, for the vibrational amplitudes involved are supplied thereto. In a speci?c device intended for operation in the range mechanical ohms at 70° F. has‘ been found ej?ec= tive to prevent motion of the driving pin .Giat square sound pressures of the order of 300ildynes second,'a ?lter wherein the stiffness- was of ap- - proximately 4x106 dynes per centimeter and the noted above and capable of producing root mean ' frequencies above about 10 cycles per second even 10 per square centimeterat a distance of 1 foot from though the amplitude of the diaphragm displace - ‘the front of the device, .a diaphragm wherein ment in the operating rangewas several times ' ‘the inner and outer diameters of the bodily that below this range. , vibratile portion 33 are approximately 3 inches _ When the submarine signaling device is sub ‘and 8 inches, respectively, this portion was vi-, _ ( merged, the diaphragm is displaced inwardly due 16 bratile at amplitudes of ‘the order of 0.41 cen to the increasing'hydrostatic pressure thereon. timeter from its neutral position and a driving This displacement of thediaphragm results 1in motion of the driving‘pin 6;] as described above,_ coil capable of radiating of the order of 125 watts _ as heat vhave been found satisfactory. so that the microswitch contacts are closed and The response frequency characteristic of the _ the solenoid 55 is actuated to open the'valve 53, 20 devicewill be determined by the mechanical whereby air under pressure ?ows from the cham constants of the diaphragm‘and the parameters of the acoustic elements associated. therewith. In a construction‘ found particularly satisfactory, the diaphragm constants were such that the resonance frequency of the diaphragm was approximately 23 cycles per second in open . ber 49 into the housing 20. Thus, the pressure I actingvupon the rear face of the diaphragm_'is increased. when the latter pressure is equalto the hydrostatic pressure upon the front face of . the diaphragm, the‘ diaphragm is returned to, its initial position, the microswitch operates to open ' water, the e?ective mass of the vibratory sys- ' the solenoid circuit and the valve 53 closes. tem being approximately 450 grams and the stiffness of’ the suspension. portions tdandt? ' Hence, the diaphragm is maintained in-its nor mal neutral position for operation at any desired 30. being approximately 48x10“ dynes per‘ centi- '4 depth. In a speci?c construction, it has been? meter.4 The diaphragm resonance may be found that the me a position of the diaphragm damped by a plurality of acoustic resistances, two~ is maintained within‘i 10.010 inch, while vibra-' of‘ which are shown on Fig. 2, each defined by tional amplitudes of ‘the diaphragm, in accord a metallic cylinder 8? provided with a multiplies‘ ance with signals, of at least ten'times this value 35 ity of_fine .slets, ?tted in the apertures in the are permitted without operation of‘ the micro frame ti and closed at one end by a cap 88. The switch. . frame 88 is imperforate except for the openings ‘ When the signaling device is raised, the pres in which the cylinders 8? are ?tted and de?nes with the diaphragm and the pole pieces a cham to maintain equilibrium between the pressures 40 ber which is made of such small volume that it upon opposite sides of the diaphragm; For this does not reduce appreciably the, flow of air sure within the housing is reduced automatically purpose, there is provided a vent which comprises a coupler 1:8‘ threaded into the housing 2% and having therein a bore 11 and a recess 78, the lat ter having a port-‘I9 communicating therewith. Secured in water-tight engagement with the cou ' pler ‘it. is a cap 86 into which a slender tube 8| communicating with the bore ‘I1 extends. A sec-' through the apertures within the band of fre quencies ‘ adjacent . - resonance volume that varlationsin its stiffness when the depth- do not alter the resonance frequency of the vibratory, ‘system by more than of they order of 10 per cent. Inaspeci?c construction, a cham ber having a volume of the order of 19X 10? cubic centimeters has been found satisfactory, result ets or clamps 88. Disposed within the recess and opening is positioned. diaphragm signaling device is. submerged to a prescribed ' ond open-ended slender tube 82 extends from the port ‘it and isaf?xed upon the housing by brack positioned by four pins 88 is a ?oatable ball at over which a disc 88 having a restricted central the frequency. The largechamber bounded by- the' ' a housing to and the frame at is made of such > ing in a change of not more than 10 per cent in the resonance frequency of the vibrating system _ - Whenthe pressures‘upon opposite sides of the 55 when the device is submerged to a depth of 50 diaphragm are equal, the hydrostatic pressure . feet. With such‘ device, a sound ?eld wherein within the cap 8d established by way of the tube 82, coun'terbalances the pressure within the cap the pressure is constant within 511.0 decibel over the operating range from 20 to 350 cycles per. due to the air within'the housing 26. vIf‘ the sig- - second has been obtained. naling device is raised, the pressure within the 60 The submarine signaling device illustrated in Figs. 7 to 9 is of generally the same construction‘ as that illustrated in Figs. 1 to '6, inclusive, and’ housing exceeds the hydrostatic pressure so that air is released from the housing by way of the port ‘it and tube 82 until equilibrium between the two pressures is established. . ' described hereinabove but ‘differs therefrom in the control system for effecting compensation The ball 85 in cooperation with the disc 85 65 for variations in the hydrostatic pressure upon the diaphragm. Specifically, the compensating constitutes a check valve to prevent ?ooding of the cap to and flow of water into the housing‘ .system included in the device illustrated in Figs. 2c in the event of failure of the compensation. 7 to 9 comprises the solenoid controlled valve- 53 As has been noted hereinabove, in a specific for allowing?owof air from the reservoir (it into device of the construction described, the intended 70 the interior of the housing 2@ to counteract hy operating range is substantially 20 to 350 cycles drostatic pressures acting upon the diaphragm, and a second solenoid controlled valve 8i having per second.‘ In such a device, a number of param» eters must be correlated in a particular manner especially if, uniformity of response over the op-v a restricted inlet gland having its outlet con. nected by a pipe 93 to the vent 9d, the valve 9i. erating range and high power capacity are to be 75 when open, allowing release of air from the in 2,411,866 7 8 . terior of'the housing 20 when the air pressure within the housing exceeds the hydrostatic pres sures upon the diaphragm. The vent 94 may bi! similar to the vent 80 and provided with an out let 95. The energizing circuit for the solenoid of valve 53 includes the microswitch 58 and that for the solenoid of valve 9| includes a similar impedances of a mechanical mesh associated with the diaphragm. If these impedances are corre lated so that the resonant frequency of the mesh is well below the intended operating range of the device, the rocker 99 will remain substantially stationary when the diaphragm vibrates at fre quencies within this range but will be tilted, in microswitch 96, the two microswitches being mounted upon a support 91 secured to the pole piece 24. ‘ 5‘ "1 ' ‘ The support 91 comprises parallel arms 98 from which a rocker member 99 is supported by trun nions I90. The rocker member includes a pair of transverse strip members NH carrying adjust able contactors I 02' for engaging the actuating buttons of the microswitches, and carries at its ends weights I93, the purpose of which will be pointed out hereinafter. The rocker member_ the manner described above, in response to ‘changes in hydrostatic pressure upon the dia 10 phragm, to effect operation of the microswitches and thus result in equalization of the pressures acting uponopposite sides of the diaphragm. In a particular device intended for operation in a range of frequencies from 20 cycles per second up, the impedances may be correlated so that the mesh noted is resonant at about 6 cycles per second. . In some cases, dissipating or mechanical re and weights are constructed and arranged so sistance elements may be provided in association that normally ‘the rocker assembly is balanced 20 with the rocker arm 99 to increase the discrim~ with respect to the trunnions and the contacts ination between vibrations of the diaphragm at I92 are spaced slightly from the actuating but the intended operating frequencies of the device tons of the microswitches whereby, normally, and at lower frequencies, as to their effect upon ‘both solenoids 55 are" deenergized and both the the rocker arm. ‘ , valves 53 and 9| are closed. The rocker 99 is 25 Although speci?c embodiments of the invention actuated by the drive pin 6| by way of a gener have been shown and described, it will be under ally U-shaped spring I04 which has its opposite . stood that they are but illustrative and that vari ends secured to the drive pin and the rocker. ous modi?cations may be made therein without member. ' Brie?y, the operation of' the compensating 30 departing from the scope and spirit of this inven tion as de?ned in the appended claims. system is as follows: As noted heretofore, nor What is claimed is: mally, that is, when the diaphragm is at its l. A submarine signaling device comprising a neutral position, both valves 53 and 9| are closed. ‘ diaphragm having one face for communication When the signaling device is submerged, due to the increasing hydrostatic pressure thereon the 35 with the sea, means de?ning a chamber with the opposite face of said diaphragm, signal translat diaphragm is displaced inwardly so that the ing means cooperatively associated with said dia rocker member 99, driven by the pin BI, is tilted phragm, and means for compensating for varia in the clockwise direction to operate the micro tions in hydrostatic pressure upon said one face switch 58, thus causing the valve53 to open. _Air from the chamber 49 flows into the interior of 40 to maintain the pressures on said one and oppo site faces substantially equal, said compensating the housing 20 to counteract the hydrostatic means comprisingv a, reservoir containing a gas pressure upon the diaphragm, vuntil the dia under pressure, a normally closed valve between phragm is returned to its neutral position. If said reservoir and said chamber and means actu the pressure within the housing 29 exceeds the hydrostatic pressure on the diaphragm, as occurs 45 ated in accordance with displacement of said dia phragm only at frequencies below a preassigned when’ the signaling device is raised, the dia frequency and in the direction corresponding to phragm moves outwardly so that the rocker increase in said hydrostatic pressure for opening member 99 is tilted in the counterclockwise di-' said valve. _ ‘ rection to cause operation of the microswitch 96. 2. A submarine signaling device comprising a Consequently, the valve 9| is opened. and air diaphragm having one face for communication escapes from the housing through the vent 94, with the sea, said diaphragm having a bodily 95 until the diaphragm is restored again to its neutral position. Thus, equilibrium between the static pressures acting upon the opposite sides of the diaphragm is maintained. vibratile portion and a. ?exible mounting portion, means de?ning a chamber with the opposite face 55 of said diaphragm, signal translating means c0 The actuating means for the microswitches constitutes a mechanical system which discrimi nates between slow or very low frequency dis— . placement of the diaphragm and vibration there operatively associated with 'said diaphragm, a reservoir containing a gas under pressure, a valve for coupling said reservoir to said chamber, ac tuating means for said valve, and means includ of at higher frequencies, whereby the micro: 60 ing a driving element coupled to said ?exible mounting portion of said diaphragm for operat switches are operated only in response to dis placement of the diaphragm at frequencies below ing said actuating means to open said valve when the lowest frequency in the intended operating the pressure upon said one face exceeds that upon frequency range of the signaling device. said opposite face. It will be apparent from-a consideration of 65 the mechanicalsystem involved in the operation ~ 3. A signaling device for translating signals within a preassigned operating frequency range, comprising a diaphragm, means de?ning a cham of the rocker 99 that the motion of the rocker in relation to frequency of displacement of the dia ber with one faceof said diaphragm, a reservoir phragm will be dependent upon the parameters containing a gas under pressure, a valve coupling of the rocker, spring I“ and spring arm' 90 con-' 70 said reservoir to said chamber, actuating means for said valve, and means for operating said valve sidered as mechanical impedances. The rocker is essentially a mass, the major portion of which in response to displacement of said diaphragm is provided by the weights I93, and the spring only at frequencies below the operating frequency I04 and spring arm 60 are essentially stiffnesses. range of the device, said operating means com The three elements ‘noted constitute the essential 76 prising a driving member coupled to said dia earnest ,9 _ in phragm and ajmechanical .impedance element having therein a ‘viscous ?uid, 'a‘paddie member, coupled to said driving member. immersed in ‘said. fluid, and ~means connecting said paddle member to said driving member, . ' 4. A signaling device for translating signals within a preassigned operating frequency range, comprising, a diaphragm, means _ de?ning 10. A submarine signaling device for translat ing signals within a preassigned operating fre quency range, comprising a diaphragm having one a chamber with one face of said diaphragm, a re's ervoir containing a gas under pressure, a valve coupling said reservoir to said chamber, and means for operating said valve only in response face for communication with the sea, means de?n - ing a chamber with the opposite face of said dia - phragm, and means for compensati?g for hydro- _ Y ‘to displacement of said diaphragm at frequen 10 static pressure upon saidone face, said means comprising a reservoir containing a gas under cies below the operatingfrequency range of the - device, said operating means including a mechan- , chamber, means for operating said valve and ac ' ical resistance-stiffness ?lter actuatedby said diaphragm. > ~ pressure, a valve, coupling said reservoir to said _ ' tuating means for said operating means respon . 5. A signaling device for translating signals 15 sive only to displacement of said diaphragm at frequencies below the operating range of the de within a preassigned operating frequency range, vice, said actuating-means including a casing comprising a diaphragm, means de?ning a, chamcontaining'a viscous fluid, a paddle member oscil-_ her with one face ofsaid diaphragm, a reservoir containing a'gas under pressure, a valve coupling - latable in said ?uid and a driving connection to said reservoir to said chamber, and means for 20 said paddle member including a spring actuated by displacement of said diaphragm. l actuating said valve only in response to displace ‘11. A submarine signaling device for translate ment- of said diaphragm at frequencies below ing signals within a preassignedv operating fre the operating frequency range of-the device, said quency range, comprising a diaphragm having actuating means comprising a mechanical link age actuated in response to displacement of said one face for communication with the sea, said dia'phrgam and including a mass and a stiffness diaphragm having'aiso a spring portion adja cent its periphery, means de?ning a chamber with the opposite face of said diaphragm, a reservoir resonant at a frequency below said range. 6. A signaling device for translating signals within a preassigned operating frequency range, - comprising a diaphragm, means de?ning a cham ber with'one face of said diaphragm, and'means for maintaining substantial equilibrium between the pressures upon said one face and the opposite 30 i containing a gas under pressure, asclenoid op erated valve coupling said reservoir to said cham- _ . her, a microswitch for controlling energization of the solenoid for said valve, and means for ac-‘ tuating said switch to effect opening of said valve , - face of said diaphragm, said equilibrium main when the pressure upon said one face is greater taining means comprising means responsive only to displacement of said diaphragm at frequencies below the. operating range of the device for in creasing the pressure in said chamber when the than that upon saidopposite face-said actuating means being responsive only?to displacement of said diaphragm at frequencies below the operat-v ing range'of the device and comprising a me chanical frequency discriminating linkage in pressure upon said .one face is less than that upon said opposite face and means for decreasing the 40 eluding said spring portion, between said dia phragm and theactuating element of said switch. pressure in said chamber when the pressure upon , 12. A submarine ~signaling device in accord said one face exceeds that upon said opposite face. ance with claim 11 wherein said linkage includes '7'. .A. signaling devicein accordance with claim ‘ in addition to said spring portion a highly viscous 6 wherein said pressure increasing means com ' body and a paddle member immersed in said body prising a reservoir containing a gas under pres and connected to said spring portion, sure, a valve coupling said reservoir to said cham 13. A submarine signaling device in accord ber, operating means for said valve, and means ance with claim 11 wherein said linkage comfor actuating said operating» means in response to prises in addition to said spring portions. sun displacement of said diaphragm including a me- ' chanical ?lter element coupled to said diaphragm. 50 ness element and a mass element, the combina- ‘ 8. A signaling device in accordance with claim 6 wherein said equilibrium maintaining, means tion of said stiffness and mass elements and said _ spring portion being vresonant, at a frequency be low said operating range. comprises a reservoir containing a gas under . 14. A submarine signaling device for translatpressure, a valve coupling said reservoir to said chamber, a venting valve for said chamber,‘ and 55 ing signals within apreassigned operating fre quency range, comprising a diaphragm one face means for operating said ?rst and second valves of which is adapted ‘to be exposed to the sea, to open said ?rst .valve when the pressure upon signal translating means cooperatively associated said one face is less than that upon said oppo» with said diaphragm, means de?ning with said ~site'face and to open. said second valve when the pressure upon said one face is greater than that 60 diaphragm a chamber opposite the other face thereof, a second chamber containing a gas under upon said opposite face, said operating ,means comprising a mechanical impedance element cou pressure, valve means connecting said chambers, pled to and ‘actuated in response to displacement relief valve means associated with said first cham ber, actuating means operable in response to dis of said diaphragm ‘and including mass and sti?a ness resonant at a frequency below said operat 65 placement of said diaphragm‘for controlling said ing range. ‘ 9. A signaling device comprising a diaphragm having a ?exibieportion, means de?ning a cham ?rst and relief valve means to maintain ‘the pres sure upon said other face of said diaphragm sub stantially equal to the pressure on said one face thereof,'and means for preventing operation of her with one faceof said diaphragm, a reservoir containing a gas under pressure, a normally closed 70 said actuating means in response to vibrations. of solenoid operated valve coupling ‘said reservoir _ to said chamber, control means for the solenoid including ‘a switch, a driving member coupled to said ?exible portion of said diaphragm and to the said diaphragm at frequencies within the operat ing range of the device._ ' _ - - ' 15. A. submarine signaling device for translat ing- signais within a preassigned operating fre actuating element of said‘ switch, a container 75 quency range, comprising a diaphragm having . ' - ‘ . 2,411,865 11 12 one face for communication with the sea, means de?ning a chamber with the opposite face of said diaphragm, a ?rst solenoid operated valve for venting said chamber, a microswitch for the solenoid of said ?rst valve, a reservoir contain ing a gas under pressure, a second solenoid oper upon said one face and to actuate said second switch when the pressure upon said one face ex _ ated valve coupling said reservoir to said cham her, 'a second microswitch for the solenoid of said second valveb a rocker member for operating said ?rst and second switches, means for tilting said 10 rocker member to actuate said ?rst switch when the pressure upon said opposite face exceeds that ceeds that upon said opposite face, said tilting means including a connection between said dia phragm and said rocker member‘ and having a sti?’ness therein, and mass means carried by said rocker member and resonant with said stiffness at a a. frequency below the operating 'range of the device. ~ LEE G. BOSTWICK. JOHN H. KING.