US2411146A

US2411146A - Sound signaling apparatus

Info

Publication number: US2411146A
Application number: US103163A
Authority: US
Inventors: Ivan C Clement
Original assignee: Submarine Signal Co
Current assignee: Submarine Signal Co
Priority date: 1933-06-14
Filing date: 1936-09-29
Publication date: 1946-11-19
Anticipated expiration: 1963-11-19

Description

NOV. 19,1946. L Q CLEMENT 2,411,146

SOUND SIGNALING APPARATUS Original Filed June 14, 1933 INVHQTOR. Ivan C. CLEMENT Patented Nov. 19, 1946 UNETED srnrss SOUND SIGNALING APPARATUS Ivan C. Clement, Greenwood, Mass., assignor, by

mesne assignments, to Submarine Signal Company, Boston, Mass, a corporation'of Delaware Original application June 14, 1933,- Serial No.

675,700. Divided and this application September 29, 1936, Serial No. 103,163

The present invention is a division of my cpending application Serial No. 675,700, filed June 14, 1933. a v

The present invention relates to an apparatus for transmitting and receiving submarine or subaqueous signals, and more in particular to the use of compressional waves in a frequency range above or near the upper limit of audibility of the human ear.

The invention further relates to the transmission of a directive beam of compressional waves with the use of piezo-electric crystals which may be quartz. but preferably areRochelle-salt crystals or crystals having similar piezo-electric properties.

In the present invention crystals of the Rochelle-salt type are not used purely as a socalled compressional crystal in which a compreselectrode.

The device of the present application may in particular be used to receive supersonic waves within a broad range-of frequencies and by the 8 Claims. (01.177-386) central piece 2 at thebottom of the casing. This support may be circular so that the whole device canbe mounted in a bearing and rotated about 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 apparatus as shown more particularly in Fig. 2.

I Within the back plate 3 is a recess within which a plurality of piezo-electric crystals is mounted. Each of the crystals 25 is supported by

rubber corners

26, 21 and 28 into which the corners of the crystal fit. Each crystal is provided with

electrodes

29 and 30 on opposite sides thereof. The electrode 29, as indicated, may be connected to conductor 3i and the electrode 30' to the conductor 32. All the crystals may in this manner be the free corners of the crystals and through use of a plurality of crystals substantially aligned in the same plane covering a large surface as compared with the wave length of the wave which is being transmitted or received. A directional beam may be transmitted when the device is used as a transmitter orthe device may act as a directional receiver, in which case it receives waves from substantially one direction.

The apparatus will be more fully described in connection with they description of the embodiment illustrated in the drawings in which Fig. 1

shows a plan view of the apparatus with the diaphragm and cover plate removed; Fig. 2 shows a sectional view along the line 2-2 of Fig. 1; Fig. 3 shows an enlarged perspective view of the arrangement of an individual crystal; and Fig. 4 shows a perspective view of a modification of Fig. 3.

With reference to Figs. 1, 2 and 3 of the drawings a plurality of crystals 25 is mounted w thin a casing -lwhich is supported preferably by a connected in parallel with each other or in some other desired manner. The

corners

28, 21 and 28 supporting the three comers of the crystal may be of any yielding material such as molded rubber but I prefer to use the substance which is known as glyptal and is a synthetic rubber possessing the desirable quality that it. is yielding but has only slight elasticity. .1

are held in position in the casing i by means of the plate 33 which is supported on a shoulder 34 in th cttsing by means of the screws 35. The plate 33 is perforated at points corresponding to these perforations the

rods

36, 31, 38, etc., operate transmitting acoustic vibrations to the' free corners of the crystals. The rods themselves may be of rubber or other molded material or they may be metallic. The rods are by one end firmly attached to the crystals and by the other end to a diaphragm 39 which is preferably made of soft rubber. The diaphragm 39 can be held in place by a clamping ring 20 suitably fastened to the 40 back of the casing by means of th screws 2| arranged around the periphery of the casing.

In the operation of the devic the sound wave .energy impressed vupon the diaphragm 39 is transmitted through the rods 36, etc., to free portions of the crystals, thereby causing a bending of the crystals between the free and supported corners. This bending creates a potential difference between the faces of the crystals which is detected in the receiver or receiving circuit.

If the device is used as a transmitter, electrical energy is applied to the electrodes of the crystals and the latter are made to bend in the same manner as they are bent when excited by compressional waves. It will be noted that the crystals 59) are placed in substantially the same plane and w time:

The crystals with the molded comers attached that the rods connecting the diaphragm with th crystals end in substantially a single plane. With this arrangement the sound energy approaching 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 normal direction excites the crystals out of phase.

In this way it will be readily understood that the device is highly directional in a direction normal to the surface of the diaphragm.

In Fig. 4 a slightly difierent form of crystal structure is shown. In this figure two similar crystals 40 and M are mounted in face to face contact with an electrode between them. The crystals are arranged so that the same polarity is produced at the top and bottom electrodes of the combination with the other polarity on the common electrode between the two crystals. The crystal structure or unit illustrated in this figure may be substituted for that shown in Fig. 3 and will operate and act in substantially the-same way but with an enhanced effect.

Having now described my invention, I claim:

1. A submarine transceiver including a casing having a rigid back element, a plurality of piezoelectric crystals of the Rochelle salt type having two parallel flat surfaces of polygonal shape, means for mountingsaid crystals in said casing in substantially the same plane, supporting the same at some of the corners thereof and means acoustically connecting said crystals to the propa' gating medium to exert acoustic vibrations on at least one of the unsupported corners thereof.

2. A submarine transceiver including a'casing having a rigid back element, a plurality of-piezoelectric crystals of the Rochelle salt type having two parallel fiat surfaces of polygonal shape, means for mounting said crystals in said casing in substantially the same plane, said means including corner elements for holding said crystals 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 having a rigid back element, a plurality of piezoelectric crystals having two parallel fiat surfaces of polygonal shape, means for mounting said 4. A submarine transceiver including a casing having a rigid back element, a plurality of piezoelectric crystals having two parallel flat 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 secured to the free corners of each of said crystals and to said diaphragm.

5. A- submarine transceiver including a casing having a rigid back element and a recess in one face thereof, a plurality of piezo-electric crystals of prismatic shape, means for mounting said crystals in said recess leaving at least one comer of each crystal free, a diaphragm secured to said casing and adapted to cover said recess and means for connecting the free corners of the crystals to said diaphragm.

6. A submarine transceiver including a casing having a rigid back element and a recess in one face thereof. a plurality of piezo-electric crystals of prismatic shape, means for mounting said crystals in said recess leaving at least one corner of each crystal free, a plurality of rods, one secured to a free portion of each crystal, a plate having a plurality of apertures therein adapted to fit over said rods in non-contiguous relation thereto and adapted to be secured to said casing and a diaphragm secured to each of said rods and to said casing for acoustically connecting the rods to the sound propagating medium.

7. An electromechanical,interchanging device, comprising in combination, a diaphragm, a casing, a plurality of piezo-electric crystal units, means for mounting said crystal units within said casing substantially in the same plane for flexural movement with at least a portion of each unit free from the mounting means and individual means for connecting said units at least at the unsupported portions thereof to the diaphragm 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 crysta units in some areas near the side edges thereof within said casing with the crystal units positioned substantially in the same plane, and individual means connecting each of said crystal units in areas at 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 are operated with a flexural movement.

- IVAN C. CLEMENT.