Nov. 12, 1946- R. BLACK, JR., ETAL. SUBMARINE SIGNAL DETEGTO R Filed Jan. 9. 1942 2,410,806 Patented Nov. 12, 1946 2,410,806 GFFICE UNITED 2,410,806 SUBMARINE SIGNAL DETECTÜR Robert Black, Jr., South Grange, and Frank F. Romanow, Berkeley Heights, N. ll., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application `lanuary 9, 1942, Serial No. 426,130 3 Claims. l » This invention relates to electromechanical transducers and, more particularly, to such de vices for use in detecting signal waves or other (Cl. lill-_0.5) 2 with successive portions broken away or in sec tion to- bring out details of construction; Fig. 3 is another view, enlarged, of the detector or microphone unit of the device of Fig. 1, partly disturbances in a liquid medium, specifically, . water. Ox in section and partly broken away; Fig. 4 is a top plan view of the insulator disc An object of the invention is to detect under immediately under the diaphragm of the micro water signal waves or other disturbances in a simple eiîective manner. phone unit; and Another object is to protect the detecting Fig. 5 is a cross-sectional View, enlarged, of a fragment of the device of Figs. 1-4 to show in means or unit from the water, without affecting the detecting properties of such means or unit greater detail the diaphragms of the device and and without requiring any complex pressure the tensioned condition of the outer diaphragm. . equalizing means because of the hydrostatic The electromechanical transducer, submarine pressure head existing at the depth at which the signal detector or microphone embodying the in detecting means might be submerged. vention and shown in Figs. 1 to 5 comprises a .A feature of the invention comprises enclosing heavy case or enclosure Ill of metal including a known type of telephone receiver unit in a case a cylindrical cup-shaped portion II and a clo orenclosure with its diaphragm opposite an ap sure or cover plate or portion I2. These portions erture ina wall portion of the case and closing are secured together by a plurality of screws I3, such aperture against water ingress with a flexi 20 a water-tight seal being provided by virtue of the ble diaphragm. annular ridge I4 on the plate fitting into the an Y Another feature comprises shaping such aper nular rubber-ñlled groove I5 in the portion Il. ture so that it flares outwardly from the inside The base or planar wall portion I6 of the portion of the case, and employing rubber as the mate , II is recessed on its outer surface to receive a rial of the flexible diaphragm. circular insert or diaphragm Il of flexible, elastic In accordance with this invention, a known or resilient material, preferably soft rubber, ce type of telephone receiver unit is mounted in a mented to the base I6 where adjacent thereto. case having a flaring, or, speciiically, frusto An annular clamping member I8 is fastened to conically shaped, aperture in one wall portion , the case portion II by a plurality of screws I9, opposite which is located the diaphragm of the ‘its inner portion overlapping the marginal area receiver unit. A relatively thick diaphragm of of the diaphragm I'I and having an annular ridge 20 protruding into the rubber insert. The base flexible material, preferably rubber, is clamped against and cemented to the water side of the I ß contains an aperture or passage 2| of sub case wall portion so as to overlie the aperture ‘ ,_ stantially frusto-conical shape, having its smaller and seal the case interior against water ingress base at the inner surface and its larger base at through the aperture. The receiver unit is so the outer surface of the case portion II. constructed and so spaced from the apertured . The ñuid chamber 22 contains a telephone re wallportion that the iluid, for example, air, in ceiver unit 23 of a type manufactured by the the case, may flow, at a very low rate, between Western Electric Company. This unit 23 em the front and back sides of the diaphragm of the bodies the magnetic circuit, acoustical network unit. Connection between the terminals of the and electroacoustical circuit such as is incorpo receiver unit and suitable indicating or recording rated in the receiver unit shown in Figs. 1 to 5 electrical equipment at a point remote from the of L. A. Morrison et al. Patent 2,220,942 of No described device, is made through a cord or cable, . ‘vember 12, 1940, but diliers from the latter re which may also constitute the means to support ceiver unit principally in the character of the' the device in the water. protector plate in front of the diaphragm and in ` Other objects and features of the invention will the means for securing the protector plate to the be apparent, and a more complete understand receiver unit frame. ing of the latter will be derived from the detailed Specifically, the unit 23 comprises a cast metal description that follows, taken in conjunction with the appended drawing, wherein: Fig. 1 is a cross-sectional View of a submarine signal detector or microphone embodying the in vention; frame 25 having a pair of projections or bosses 2t to which are secured by rivets 2S' L-shaped pole-pieces 28 and an insulator terminal plate or disc 3Q. Windings or coils 3l encircle the vertical legs of the pole-pieces, and are connected in se Fig. 2 is a top plan View of the device of Fig. 1 55 ries between the concentric spaced terminals 32, 2,410,806 3 33. A pair of bar permanent magnets 21 are welded to and extend between the horizontal legs of the pole-pieces. An insulator plate or disc 35 contains a pair of appropriately shaped open 4 invention, the diaphragm I1 was about 2.5 inches in diameter and about .125 inch in thickness; wall portion I6 was about à inch in thickness; the large base of the aperture 2l was about .5 inch ings for the upper ends of the pole-pieces, and, 5 in diameter and its small base about .25 inch in also, an aperture or passage 40 over which is laid diameter, the aperture being centrally located in one or more strips of silk fabric 5D. The dia the base lf3. The distance between the inner phragm 35 forms a shallow air chamber 38 with surface of diaphragm Il and the outer surface the plate 36, and is supported at its peripheral of diaphragm 35, with the device out of the water, portion by the frame 25, the diaphragm being was of the order of .25 inch. The device re held in position by magnetic attraction under the sponded effectively to vibrations over a band of influence of the permanent magnet flux. The frequencies from about 200 cycles per second to diaphragm protector plate is a multiaperture about 4000 cycles per second. Fig. 1 shows ap sheet metal stamping 6Fl secured to the frame at proximately the relative proportions of the com its edge by the spun-over metallic annulus 6l. 15 ponents of the device. A moisture-prooñng diaphragm 62 of oiled silk , The term transducer refers to a device absorb may be interposed between the diaphragm Sii and ing power from one system and supplying power the protector plate. The structure on the under to another system or systems. These systems side of the plate 36 is so proportioned and ar may be electrical, mechanical or acoustical. ranged that the chambers 22 and 38 are intercon Although this invention has been disclosed with nected through the passage lill. reference to a specific embodiment, it will be ap The unit 23 makes a loose fit with the cylindri parent that it is not limited thereto, but is of a cal inner surface of the case portion ll, with scope evidenced by the appended claims. its diaphragm 35 disposed opposite the small base What is claimed is: of the aperture 2l. A thin split ring washer 63 25 l. A submarine signal detector comprising a is interposed between the unit 23 and the base water-tight fluid~containing enclosure, having a S5, the gap 64 providing an air passage for slow wall portion with an aperture that flares out air leak between the front and rear sides of the wardly between inner and outer surfaces of the diaphragm Electrical connection of the unit wall portion, a fiexibie rubber diaphragm con 23 with indicating or recording electrical equip 30 tiguous with and fastened against said outer sur ment at a remote point, is made through cord face to prevent water entering said enclosure or cable ëë containing conductors 65 terminated through said aperture, and a diaphragm within at spring terminals Sii, tl carried by insulator said enclosure spaced from said inner surface and plate §53 and engaging with the terminals 3‘2, 33 of the unit. The gland lil provides a water 35 arranged so that iluid within the enclosure may now between opposite sides of the diaphragm. tight seal around, and also acts as a strain re A signaling device for use in a liquid medium, liever for the cable. comprising a hollow container having an aperture When the device of Figs. 1 to 4 is submerged in one wall, a diaphragm of elastic material on in water the hydrostatic pressure head acting on the rubber diaphragm Il will increase as the> 40 the outside of said container and overlying said aperture, said diaphragm under pressure of the depth or submersion is increased. Under the liquid medium being adapted to be forced increased force, the rubber diaphragm will tend partially into said aperture and thereby ten to be forced into the aperture 2l. Because of sioned; a unitary assembly within said container the flaring wall contour of the latter, even a very great pressure will do no more than cause the 45 and including a diaphragm and a plate form ing a shallow air chamber with one side of the central portion of diaphragm l'l to assume the diaphragm, said plate containing an aperture general position indicated in enlarged detail in connecting said air chamber with the remaining Fig. This will be a small-area stretched dia space in the container, the other side of the phragm coupled to the diaphragm of the re ceiver unit through the air space or chamber 50 diaphragm being disposed opposite to the aper ture in the container wall portion; and spacer between. Obviously, the volume change in front means between the unitary assembly and said of the diaphragm 35 because of the displacement Wall portion, containing a restricted air passage of diaphragm il is small, and, with the presence connecting the space between the unitary as of the pressure equalizing leak 64, does not re sult in any pressure unbalance or non-equaliza 65 sembly and said wall portion with the remaining space in the container. tion developing with respect to the diaphragm 3. A transducer for use in a liquid medium The stiffness of the portion of the diaphragm comprising a fluid-containing enclosure exclud l? overlying the aperture is increased as a result ing the liquid medium and having a wall por of its deformation and its radiation mass is reduced. 60 tion with an aperture therein that flares out An underwater signal wave or other disturb wardly between inner and outer surfaces of the ance incident on the portion of diaphragm Il wall portion, a diaphragm of elastic material overlying the aperture 2l, is transferred to the contiguous with and fastened against said outer diaphragm 35 through the air space between the surface to prevent entrance of the liquid medium two diaphragme. The vibration of diaphragm 65 into said enclosure through said aperture, the portion or” said diaphragm overlying said aper 35i in response thereto varies the reluctance of the magnetic circuit of the receiver unit, and the reture being forced into said aperture by the liquid sultant changes in ñux in the pole-pieces induce medium whereby said diaphragm portion is ten in the colis 3l currents corresponding to such sioned, and a second diaphragm, said second dia changes. These currents are led over the phragm being within said enclosure and spaced 70 conductors of the cable to suitable indicating or from said inner surface. recording electrical equipment (not shown). ROBERT BLACK, J R. In a device constructed in accordance with this FRANK F. ROMANOW. .