US1463911A - Sound producer and receiver - Google Patents

Description

Aug. 7, 1923. 1,463,911

w. RUDOLPH SOUND PRODUCER AND RECEIVER Filed Aug. 14 ,1920

Patented Aug. 7, 1923.

WILHELM RUDOLPH, OF KIEL, GERMANY, ASSIGNOR TO FIRM SIGNAL GESELLSCHAFT PATENT orrica.

M. B. H., OF KIEL, GERMANY.

SOUND PRODUCER/AND RECEIVER.

Application filed August 14, 1920. \Serial No. 403,542.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L., 1313.)

To all whomit may concern Be it knpwnjhatfll, WILHEL'M RUDOLPH, a citizen of the German Republic, and re- Sldlllg at Kiel, county of Schleswig-Holstein, State of Prussia, Germany, have invented certain new and useful Improvements in Sound Producers and Receivers (for which I have filed a plications in Germany on March 9 1916, atent No. 299,130; in Denmark on ay 2, 1919, Patent No. 28,212; in Sweden on May 14, 1919; in Norway on May 15, 1919', Patent No. 36,540; in'

Holland on June 16, 1919, and July 3, 1920; in England on June 9 1920, Patent No. 144,673; in Belgium onduly 8, 1920, Patent No. 288,994; in Spain on July 7, 1920-; in France on July 8, 1920, Patent No. 532,119; and in Italy on July 9, 1920, Patent No. 541/246), of which the following is a specification.

In emitting sound waves into different mediums or in taking in or receiving these waves from these mediums the most favorable amplitude of motion that the body or structure (radiating member) which operates to pass on the energy can execute depends on the degree of compressibility of the particular medium in question. In cases in which the sound collecting or radiating member abuts on liquids for instance, small amplitudes of motion of the radiating member will suffice to produce considerable amplitudes of pressure, but to produce similar results where the abutting medium is a gas, large amplitudes of motion are required. On the other hand the proper amplitudes of motion to select for the actual exciter of the sound waves, such as the working parts actuated by the electromagnet 1n electromagnetic sound producers, or for the actual receiver, which may consist of a m crophone in a receiving apparatus, are entirely different. Hence it isnearly always necessary in sound signalling apparatus of this kind to transform the amplitudes of the motions transferred from onevpoint of the apparatusto another. I

A known means of obtaining a transformation of the amplitudes consists in interposing a separate vibratory body or stru ture between the art of the'sound signa ling apparatus t at abuts on the sound propagating medium, and the sound exciter or detector proper, and in attaching the said part and the exciter (or detector) to points of the said vibratory structure which execute amplitudes of motion of different magnitudes. Another known feature conslsts in making such vibratory structures of members whose various parts vibrate s mmetrically to an axis of the apparatus. ut as the sound exciter or detector was invariably attached to a single point of the interposed member, and the sound collecting or radiating part of the apparatus likewise, it Was necessary to adopt either an unsymmetrical point of attachment or a point lymg on the axis of symmetry. If the former plan is adopted the vibrations of the interposed vibratory structure will be unsymmetrical, and instead of only one natural rate of vibration it will have several, whereas if the second plan is chosen the number of the points of coupling open to selection is extremely small, it only being possible to connect the different parts to certain very definite points of the interposedstructure so thatgenerally speaking the ratio of transformation of the amplitudes can-only be altered by changing the size of the vibratory structure. But'as other factors are also to be considered in determining this size it will often be impossible to comply with all the re uirements at the same time.

n accordance with the invention these difficulties are overcome by effecting the coupling or attachment between the part of the sound signalling apparatus that abuts on the sound propagating medium and the vibratory structure that operates to transform the amplitudes, at two or more points which are symmetrical with respect to the nodal point or points (or line or lines) of the said structure. By this arrangement the measurements of the vibratory structure and the radiating member are rendered a matter of indifference as far as the ratio of transformation is concerned and they can therefore be determined according to other important and entirely different points of view. 4

The simplest practical solution of the problem is presented by inserting between the interposed vibratory structure and the other part or parts of the apparatus a rigid coupling member or members in the shape of a fork or two forks to whose stem (or stems) and prongs the said other parts are coupled. t each junction between the prongs and the said vibratory structure the parts are joined through a point or line, for example, by tapering the prongs to a point or to a knife-like edge, in order that the prongs will not affect the vibratory structure in an undesired manner. These prongs may be pivoted to the-vibratory structure (for lowfrequen'cy vibrations), or they may (in all cases) be soldered thereto. When soldered it is particularly desirable to sharpen or notch the prongs in order to permit them to bend and thus avert an undesired influence on the vibratory structure.

Some constructional forms of the invention are illustrated in the drawing in which Fig. 1 shows a coupling device consisting of two rigid coupling forks associated with an elastic vibratory body or structure in the form of a straight bar. Fig. 2 illustrates an arrangement in which the vibratory structure has the shape of a tuning fork, whereas in Fig. 3 the interposed vibratory structure consists of a diaphragm.

Fig. 4 represents an arrangement with an interposed vibratory structure in the form of a ring and Figv 5 shows a device with a vibratory structure composed of a ribbed band.

The arrangement of Fig. 1 comprises an interposed vibratory body in the form of an elastic bar 03 which is held firmly at the middle e. Its two halves vibrate symmetrically with respect to the axis aa as indicated by the broken lines. The ends of the bar d are the points of largest amplitude, the amplitudes decreasing continuously from the ends to the middle 6. The points of attachment or coupling are arranged in pairs, the two points of each pair being symmetrical with respect to the axis o-o. Thus the points I) and 5, which execute small amplitudes of motion and exert great forces and the points 0 and c of large amplitudes and small forces, are pairs of coordinated points; and are connected to each other in a manner suitable for the particular purpose in view by beams s and t which are perfectly still or rigid, or in other words whose tuning or natural rate of vibration is so much higher than the pitch of t is sounds to be sent or received by the apparatus that they may be regarded as being per tectly rigid. Hence every point of the beam 8 executes the same amplitudes of motion as the points of coupling 0, 0 and all points of the beam 5 execute the same amplitudes as the points Z), b,. According to the required ratio of the trans formation of the amplitudes of motion a sound exciter or detector would be connected to the one beam and a sound radiating or collecting member to the other.

In Fig. 2 the interposed elastic vibratory structure has the form of a tuning "fork g.

The axis of symmetry of the vibrations is the line (Ir-a1. The points of largest amplitude are c, 0 whilst the nodal points lie at 6, 6 In accordance with the invention the coupling is effected at two pairs of points that are symmetrical to the axis and are at the desired distance from the nodal points. In the example illustrated this is accomplished by connecting the points b, b, by a rigid beam or fork t, or in other words a fork of a very high sound pitch, and by mounting the fork on the sound radiating surface, as on the hull w of a ship.

In Fig. 3 the interposed elastic vibratory structure is made in the form of :1 diaphragm m which is held firmly in a ring with its vibrating parts symmetrical to the axis a--a. This diaphragm is, coupled at the points 6, b, (which are situated symmetric-ally with respect to the said axis) to the centre of a diaphragm M that abuts on the sound propagating medium, the coupling being effected by a rigid bent beam or fork t. In this instance the coupling points 0, c of Fig. 1, i. e. the points that execute the largest amplitudes, are united in one point 0 situated in the axis of symmetry. in this case the preferred plan would be to use a larger number of symmetrically situated coupling points lying on a concentric circle, instead of only. a pair or such points. The point 0 is connected to a. sound exciter or detector f.

In Fig. 4 a ring acts as an elastic interposed vibratory member. e, e, e", 0 denote its nodal or motionless points. In accordance with the procedure hereinbefore described the coupling is effected at a pair of points 5, b, that lie symmetrical with respect to one of the axes of symmetry. Here again the points b, b may be interconnected by a rigid beam t and joined to the sound emitting or collecting hull w of a ship, while a sound exciter or detector is applied at the point 0.

In all the cases dealt with so far it was assumed that the frequency of the sound exc ter or of the arriving sound waves concided with the pitch of the independent interposed vibratory structure. But the in* vention is not limited to such special cases for, if a suitable form of vibratory structure is chosen, it will enable the amplitudes of sound Waves of any frequency and character to betransformed. A case in point is shown in Fig. 5 in which (Z is a band or bar of a very low rate of vibration firmly fixed at both ends. In order that the bar d may only be able to oscillate as a whole it is equipped at both sides with ribs 131'. The axis of symmetry of its vibrations is (1-11.. The pair of coupling points situated symmetrically with respect to the said axis is b, b. Instead of coupling the exciter or detector at c any pair of points may be selected for this purpose as long as they lie symmetrical to the axis a-a.

Instead of a bar as shown in Fig. 5 a diaphragm stiffened by radial ribs may be em ployed. The pair of points I), 6' could then be replaced by any number of coupling points situated on a circle concentric to the axis of symmetry. The coupling point 0 could be left on the axis of symmetry or could be resolved into a number of points lying on a concentric circle around the axis of symmetry.

The ratio of the transformation of the amplitudes need not be unchangeable, for the arrangementmay be such that the distance between the pairs or groups of coupling points and the nodal points is capable of being continuously altered.

It is to be understood that the term radiating member as used in the claims designates any member which receives vibrations from the sound propagating medium and radiates them to another member or structure, or rec'eives vibrations from another member or structure and radiates them to the s6und propagatin medium. the term refers to both senders and receivers.

I claim:

1. In a device for transferring sound vibrations, a radiating member, a structure capable of executing independent vibrations, and means attached to said radiating member and adapted to transmit vibrations between said radiating member and said vibratory structure, said means engaging the latter at points on opposite sides of and equidistant from the axis of symmetry of vibrations of the latter.

2. In a device for transferring sound vibrations, a radiating member, a structure capable of executing independent vibrations, and a forked member having its stem attached to said radiatin member and adapted to transmit vibrations etween said radiating member and said vibratory structure, the prongs of said forked member engaging the vibratory structure at points on opposite sides of and equidistant from the axis of symmetry of vibrations of the latter.

3. In a device for transferring sound vibrations, a radiating member, a structure capable of executing independent vibrations, and means attached to said radiating member and adapted to transmit vibrations between said radiating member and said vibratory structure, said means engaging the latter at points each of which is equidlstant from a nodal point of the latter.

Thus

4. In a.- device for transferring sound vibrations, a radiating member, a diaphragm capable of executing independent vibrations, and means attached to said radiating member and adapted to transmit vibrations between said radiating member and said diaphragm, said means engaging the latter at diametrically opposite points each of which is equidistant from a nodal point of the latter.

5. In a device for transferring sound vibrations, a radiating member, a structure capable of executing independent vibrations and having point-s thereof adapted to execute vibrations of relatively small amplitude and other points adapted to execute vibrations of relatively large amplitude, and means attached to said radiating member and ada ted to transmit vibrations between said ra iating member and said vibratory structure, said means engaging the vibratory structure at points thereon having a relativel .small amplitude of vibration and each 0 which is equidistant from a nodal point of the vibratory structure.

6. In a device for transferring sound vibrations, a radiating member, a structure capable of executing independent vibrations and having points thereof adapted to execute vibrations of relatively small amplitude and other points adapted to execute vibrations of relatively large amplitude, and means attached to said radiating member and adapted to transmit vibrations between said radiating member and'said vibratory structure, said means engaging the vibratory structure at points thereon having a relatively small amplitude of vibration and located on opposite sides of and equidistant from the axis of symmetry of vibrations of the vibratory structure.

7. In a device for transferring sound waves, a radiating member, a vibratory structure, energy-converting means connected to said vibratory structure, and means interconnecting the radiating member and the vibratory structure at a plurality of points on the latter in such manner that these points are situated symmetricall to the axis of symmetry of vibrations o the vibratory structure and that the vibratory structure and the interconnecting means are adapted to transform the amplitudes of vibrations passing betweenthe radiating mem ber and the energy-converting means so that the amplitude of the vibrations at the radiating member is different from the amplitude at the energy-converting means.

8. A device according to claim 2, in which the forked member has a natural rate of vibration higher than that of the sounds to be transferred, so that it does not execute natural vibrations during the transference.

9. A device according to claim 2, in which the prongs of the forked member are sharp at the point of engagement with the vibratory structure.

10. In a device for transferrin sound waves, a radiating member, a vibratory structure in the form of a diaphragm, energy-converting means connected to said vibratory structure, and means interconnecting the radiating member and the vibratory structure at a plurality of points on the latter in such manner that these points are situated symmetrically to the axis of symmetry of vibrations of the vibratory structure and that the vibratory structure and the interconnectin means are adapted to trans form the amp 'tudes of vibrations passing between the radiatingmember and the energy-c0nverting means so that the amplitude of the vibrations at the radiating member is different from the amplitude at the energyconvertmg means In testimony whereof I affix my signature in presence of two witnesses.

. WILHELM RUDOLPH.

Witnesses: WALTER HALMEMANN, ALORD DU' BOIS RAYMOND.

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