_ NOV. 19,1946. L Q CLEMENT ' SOUND SIGNALING APPARATUS ' 2,411,146 ‘ Original Filed June 14, 1933 INVHQTOR. Ivan C. CLEMENT 2,411,146 r Patented Nov. 19,‘ 1946 UNETED srnrss ' 2,411,146 SOUND SIGNALING APPARATUS Ivan C. Clement,>Greenwood, Mass., assignor, by mesne assignments, to Submarine Signal Com- " pany, Boston, Mass, a corporation'of Delaware Original application June 14, 1933,- Serial No. 675,700. Divided and this application Septem ber 29, 1936, Serial No. 103,163 8 Claims. (01.177-386) 1 . central piece 2 at thebottom of the casing. This The present invention is a division of my c0-L pending application Serial No. 675,700, ?led June use of compressional waves in a frequency range support may be circular so that the whole device canbe mounted in a bearing and rotated vabout a vertical axis. The casing I, which may be of metal, is provided with a heavy back plate 3 which tapers somewhat to the top of the ap paratus as shown more particularly in Fig. 2. above or near the upper limit of audibility of the I Within the back plate 3 is a recess within which 14, 1933. a v The present invention relates to an apparatus for transmitting and receiving submarine or sub aqueous signals, and more in particular to the ' a plurality of piezo-electric crystals is mounted. The invention further relates to the transmis 10 Each of the crystals 25 is supported by rubber corners 26, 21 and ‘28 into which the‘ corners of sion of a directive beam of compressional waves human ear. _ ’ ' the crystal ?t. Each crystal is provided with electrodes 29 and 30 on opposite sides thereof. The electrode 29, as indicated, may be connected with the use of piezo-electric crystals which may . be quartz. but preferably areRochelle-salt crys tals or crystals having similar piezo-electric prop erties. ‘ - ' ' In the present invention crystals of. the 15 to conductor 3i and the electrode 30' to the con . ductor 32. All the crystals may in this manner be connected in parallel with each other or in some Rochelle-salt type are ‘not used purely as a so other desired manner. The corners 28, 21 and 28 called compressional crystal in which a compres supporting the three comers of the crystal may sion between two faces of the crystal s'ets'up an electrical potential in a direction parallel to the 20 be of any yielding material such as molded rub ber but I prefer to use the substance which is faces and normal to the opposite faces, but the known as “glyptal” and is a synthetic rubber crystals are used as bending crystals, and in this possessing the desirable quality that it. is yielding connection the method of support and the method but has only slight elasticity. of applying the vibratory energy to the crystal are substantially di?erent. The crystals as indi - .1 The crystals with the molded comers attached are held in position in the casing i by means of the plate 33 which is supported on a, shoulder 34 in the cttsing by means of the screws 35. The 25 cated may be used individually or they may be mounted in groups in face-to-face relation; the outer electrodes being connected together and serving as one pair of electrodes while the inner plate 33 is perforated at points corresponding to face-to-face electrodes serve as the common 30 the free corners of the crystals‘ and throughv \ these perforations the rods 36, 31, 38, etc., operate electrode. The device of the-present application may in _ transmitting acoustic vibrations to the' free corners of the crystals. The rods themselves may particular be used to receive supersonic waves be of rubber or other molded material or they‘ within a broad range-of frequencies and by the use of a plurality of crystals substantially aligned .35 may be metallic. The rods are by one end ?rmly attached to the crystals and by the other end to in the same plane covering a large surface as a diaphragm 39 which is preferably made of soft compared with the wave length of the wave ' rubber. The diaphragm 39 can be held in place which is being transmitted or received. A di by a clamping ring 20 suitably fastened to the rectional beam may be transmitted when the de vice is used as a transmitter orthe device may 40 back of the casing by means of the screws 2| ar . ranged around the periphery of the casing. act as a directional receiver, in which case it In the operation of the device the sound wave receives waves from substantially one direction. .energy impressed vupon the diaphragm 39 is The apparatus will be more fully described in transmitted through the rods 36, etc., to free por connection with they description of the embodi tions of the crystals, thereby causing‘ a bending 45 ' ment illustrated in the drawings in which Fig. 1 of the crystals between the free and supported shows a plan view of the apparatus with the corners. This bending creates a potential dif diaphragm and cover plate removed; Fig. 2 shows ference between the faces of the crystals which a sectional view along the line 2-2 of Fig. 1; Fig. is detected in the receiver or receiving circuit. 3 shows an enlarged perspective‘ view of the ar rangement of ‘an individual crystal; and Fig. 4 50 If the device is used as a transmitter, electrical energy is applied to the electrodes of the crystals shows a perspective view of a modi?cation of Fig. 3. and the latter are made to bend in the same man - ner as they are bent when excited by compres With reference to Figs. 1, 2 and 3 of the draw ' sional waves. It will be noted that the crystals ings a plurality of crystals 25 is mounted w ‘thin a casing -l- which is supported preferably by a 59) are placed in substantially the same plane and ‘w - ~ time: 2,411,146 4 3 4. A submarine transceiver including a casing having a rigid back element, a plurality of piezo electric crystals having two parallel ?at surfaces of quadrilateral shape, means for holding said crystals by three corners in substantially the same plane, a diaphragm and a plurality of rods each that the rods connecting the diaphragm with the crystals end in substantially a single plane. With this arrangement the sound energy ap proaching normal to the surface of the diaphragm excites all of the crystals in the same phase while the sound energy approaching from any but a secured to the free corners of each of said crys normal direction excites the crystals out of phase. tals and to said diaphragm. In this way it will be readily understood that 5. A- submarine transceiver including a casing the device is highly directional in a direction nor 10 having a rigid back element and a recess in one mal to the surface of the diaphragm. face thereof, a plurality of piezo-electric crystals In Fig. 4 a slightly di?erent form of crystal of prismatic shape, means for mounting said structure is shown. In this ?gure two similar crystals in said recess leaving at least one comer crystals 40 and M are mounted in face to face of each crystal free, a diaphragm secured to said contact with an electrode between them. The crystals are arranged so that the same polarity 15 casing and adapted to cover said recess and means for connecting the free corners of the crystals to is produced at the top and bottom electrodes of said diaphragm. the combination with the other polarity on the 6. A submarine transceiver including a casing common electrode between the two crystals. The having a rigid back element and a recess in one crystal structure or unit illustrated in this ?gure may be substituted for that shown in Fig. 3 and 20 face thereof. a plurality of piezo-electric crystals of prismatic shape, means for mounting said crys will operate and act in substantially the-same way tals in said recess leaving at least one corner of but with an enhanced effect. . _ Having now described my invention, I claim: each crystal free, a plurality of rods, one secured to a free portion of each crystal, a plate having a 1. A submarine transceiver including a casing having a rigid back element, a plurality of piezo 25 plurality of apertures therein adapted to fit over said rods in non-contiguous relation thereto and electric crystals of the Rochelle salt type having adapted to be secured to said casing and a dia two parallel flat surfaces of polygonal shape, phragm secured to each of said rods and to said means for mountingsaid crystals in said casing casing for acoustically connecting the rods to the in substantially the same plane, supporting the same at some of the corners thereof and means 30 sound propagating medium. ‘ 7. An electromechanical,interchanging device, acoustically connecting said crystals to the propa'— gating medium to exert acoustic vibrations on at least one of the unsupported corners thereof. comprising in combination, a diaphragm, a cas ing, a plurality of piezo-electric crystal units, 2. A submarine transceiver including a'casing having a rigid back element, a plurality of-piezo 35 electric crystals of the Rochelle salt type having two parallel ?at surfaces of polygonal shape, means for mounting said crystals in said casing in substantially the same plane, said means in cluding corner elements for holding said crystals 40 and means holding said corner elements in place, and means acoustically connecting said crystals to the propagating medium to exert acoustic vi-, brations on the unsupported corners thereof. 3. A submarine transceiver including a casing 45 having a rigid back element, a plurality of piezo electric crystals having two parallel ?at surfaces of polygonal shape, means for mounting said crystals in said casing in substantially the same means for mounting said crystal units within said casing substantially in the same plane for flex ural movement with at least a portion of each unit free from the mounting means and indi vidual means for connecting said units‘ at least at the unsupported portions thereof to the dia phragm at a plurality of spaced points over the‘ same. 8. An electromechanical energy interchanging device comprising, in combination, a diaphragm, a casing, a plurality of piezoelectric crystal units, means mounting and supporting said crystal. units in some areas near the side edges thereof within said casing with the crystal units positioned sub stantially in the same plane, and individual means connecting each of said crystal units in areas at plane, said means including comer elements for 50 other side edges thereof to the diaphragm at a plurality of spaced points over the same, said crystal units being otherwise unsupported in said last-mentioned areas whereby said crystal units holding said crystals, means for holding said corner elements in place and means acoustically connecting said crystals to the propagating me dium to exert acoustic vibrations on unsupported portions of said crystals. are operated with a ?exural movement. 55 - IVAN C. CLEMENT.