US1917007A - Sound translating device - Google Patents

Description

July 4, 1933. l G. E. ATKlNs SOUND TRANSLATING DEVICE Filed Feb, lO, 1932 2 Sheets-Sheet l /N VEN TOR G. E. ATK//vs www, @di

/FW am A TTORNEY July 4, 1933- G. E. ATKINS SOUND TRANSLATING' DEVICE 2 Sheets-Sheet 2 Filed Feb. 10, 1932 ATTORNEY Patented July 4, 1933 UNITED STATES PAraNrOFrieE GEORG-E, E. ATKINS, `or GLEN RIDGE, NEW

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snr, essie-,Nola ro ranni. TELEPHONE LABORATORIES, INCORPORATED, OFMNEW YORK, N. Yi, a oonronnTI'ON or NEW YORK SOUND TRANSLATING DEVVCE 5 Appncation flied February 1o, 1932. sel-iai No. 5e1,9e1.v

This invention relates to sound translating devices and more particularly to direct acting'loud speakers adapted for use in installations Where the diaphragm is lsubject to intense external pressure Waves, such for example as in announcing'systems on Warships, Where during gunfire abnormal pressure Waves are produced which may cause rupture or tearing ofthe diaphragm of such loud speakers;

An object of this invention is to.prevent damage of the diaphragm in loud speakers by intense external pressure Waves. Y

In one embodiment of this invention, a loud speaker comprises a casing Open at oneend and a direct-acting diaphragm and actuating unit therefor mounted Within the casing, the diaphragm being in direct communication With the atmosphere and substantially closing one end of the casing. AA stop member is provided on one or'both sides of the diaphragm adjacent that portion of the diaphragm most apt to shear When external pressure Waves impinge thereupon. These stops in one form may comprise perforated plate members conforming in contour to the adj acent portion ofl the diaphragm and spaced therefrom a distance substantially equal to the maximum amplitude of movement' of the armature or driving coil of the actuating unit.

In another embodiment thestop members comprise a rigid portion adjacent the apex or center of the diaphragm and' extending parallel to a` portion of the diaphragm, and a screen extending from the rigid portion and parallel to the remainder of the one surface of the diaphragm.

`The invention and the several features thereof will be understood more'fully and readily from the following detailed description with reference tothe accompanying .drawings in which:

Fig. 1 is a front elevational vievv of an electromagnetic loud speaker illustrating one embodiment of this invention, partlyV broken away to show the relation of certain elem-ents of the structure more clearly;

Fig. 2 is a cross-sectional view-taken along line 2--2 of Fig. l;

Fig. 3 is an enlarged detail view showing the connection of the actuating rod to ythe diaphragm Y in the loud speaker shown in Figs. 1 and 2;

Fig.' 4, is a detail vievv partly in crosssection of an actuating unit, diaphragm, 'and stop .assembly villustrating another embodimentof this invention;

F ig. .5 is a side elevational view, partlyA broken avvay and partly in cross-section, of another embodiment of this invention in which stop members are *provided` adjacent both surfaces of theV diaphragm; f

'F ig. 6 is another side'` elevational view, j

partly broken away and partly in crossfscction, illustrating still another embodiment of this invention in which a stop member extends adjacent substantially one entire face of the diaphragm; and i Fig. 7 is a side elevational `view ink crosssection illustrating the invention asapplied to amoving coil actuated sound translating device. f

f Referring now to the drawings, the loud Vspeaker shovvn in Figs. 1 and 2icomprises a casing 10 having a shoulder portion 11 ad-` jacent the front thereof. A spider member,

Which-may be an aluminum Y casting, 1s

mounted upon` the shoulder portion llnand comprises a rim 12 seated upon the shoulder portion11, and a plurality ofinvvardly ex- `tending arms'13 which terminate in an annular support 14. An annular sealing gasket v15, such as of rubber, is interposed betvveen the rim 12 and the shoulder 11 to prevent Vthe seepage Of moisture into the casing. The rim 12 and shoulder 11 ar-e secured together by a plurality of nuts and bolts 16, a gasket 17 beslioulder to providea Water-tight seal.

' A large direct-acting conical diaphragm 18, preferably of a material such as cellulose acetate, impervious to and substantially unaffected by moisture, is disposed with its apex AWithin the spider member and is'c'onnected at its periphery to the rim l2 of the spider by a flexible annulus 19, which is preferably of `a Waterproof material' such as rubber or rubberized fabric. The annulus 19 is secured to the periphery ofthe 'diaphragm in any mg interposed between the nuts and thel Y suitable'manner, asby cementing, and is attached to the rim 12 bya clamping band 20.

An ornamental and protective grille 21hav-V ing a screen 22 suitably attached thereto, and

a moisture-proof annulus V23 are clamped within the shoulder portion 11 of the casing by a split ring 24 which is disposed in a v grove in the shoulder portion 11.

apex of the diaphragm by a rod 28. The rodV 28 may be attached to the diaphragm by collars 29 which are disposed on opposite sides of the diaphragm and are secured to the rod 28 by soldering. In order to prevent damageV of the diaphragm 18 by heat during the sol? deringoperation a plurality of protective in,- sulating members 30, such as of mica, are provided between the collars-29 and the adjacent portions of the diaphragm 18 as shown more clearly in Fig. 3. The protective members 30 also result in the` distribution of the driving stresses over a larger area'of the diaphragm and thereby strengthen the joint between thediaphragm and the actuatingl unit.

' Leading-in wires 31 for the coils of the electromagnetic unit 25 extend through a bore 32 in one of the arms 13 of the spider and outwardly to terminal strips 33 mounted upon an insulating block 34 at the rear of the casing 10. External connection to the strips 33 may 'be made toline wires (not shown) which pass `through vconduits adapted to ,be threadedto housings 35 on the casinglO. During the shipping and installation of the loud speaker the housings 35 are preferably vclosed by plugs 36 to prevent the introduction of'moisture or other extraneous matter into the casing 10. The casing is provided with an opening 37 adjacent the terminal block 34 to enable the making of connections 'to the terminal strips 33 when the loud "speaker is mounted in position. The open-v ing'37 is closed by a cover plate 38 which is bolted to the casing 10, a sealing gasket 39 beingV provided tofform a moisture-,proofv joint.

In announcing systems on battleships and in similar installations, intense pressure waves are produced during gunfire, and these waves are often` of sufficient intensity to ycause rupture of the diaphragms of loud speakers incorporated in such systems. It

has been found that the point at which rupture of the diaphragm is most apt to occur is at the point ofV attachment of the actuating rod to the diaphragm.

In accordance with this invention the aforementioned deleterious eects of gunfire, uponl the d iaphragmare eliminated by Y providing stop members adjacent the diaphragm, which limit the movement of the diaphragm and therebyprevent rupture or diaphragm at thev apex, and a cylindrical or Vsleeve portion 41 which is threaded into'the support 14. The conical or mushroom shaped-portion of the stop member is lpreferably spaced from the diaphragm a.

distance substantially equalto the maximum travel of the armature 27 from its neutral position. The desired adjustmentmay be effected by positioning the stop member just in Contact with the. diaphragm 18 .and then, with'an input signal appliedto the actuan ing unit 25, rotating vthe stcp member so that it recedes from the `diaphragm until no in,- terf'erence byfthe s'top member with thevibration of the` diaphragm, due to ordinary audible frequency impulses,lis noticeable.

When intense pressure waves impinge upon the diaphragm thegieatestzstress is introduced into the `diaphragm 18 at the point of attachment tothe actuating rod 28. The movement of the diaphragm at this point is limited, however, to movement just slightly greater Ythan the maximum travel dueto ordinary audible frequency impulses,

,so that shearingV or rupture of ythe diaphragm is prevented.AV

`Thestop member may cent the concave surface of the diaphragm as shown in Fig. 4. In this embodiment the cylindrical or sleeve portiony 42 v:of the stop member is'threaded into a baror bridge arm 43 secured to ythe actuating unit25; A lock nut 44 is provided to securely position the stop member with respect to the diaphragm. rl`he procedure in adjusting the spacing of the stop and thediaphragm 45 is substantially the same as that described withk reference to the embodiment shown in Figs. 1l and` 2.

In another embodimentl of` this invention shown in Fig. 5, a pairof stops 46 and 47, maybe provided one adjacent each surface of the diaphragm. Thestop 47 is supported from thegrille'21by av threaded shank 48 ,which is adjustably secured totl'iegrille by nuts 49 andv50.' Adjustment of the spacing .of the stops 46 and 47 withreference to the diaphragm iseffected inthe manner'hereinf before described. i

The use of-two stops as shown in Fig. V5 is Adesirable when the casing is provided with apertures such .as 5.1 in the rear-wall. The

y.apertures are preferably closed 'by arsheet `v52 of 'material impervious to water, such as rubber, disposed between screens 53 and 54 which limit the movement of the sheet with variations of pressure thereupon.

In a modiied embodiment illustrated in bel disposed lil) Fig. 6, a screen 55 is provided which extends `between-the conical `or mushroom shaped stop 40 and the rim l2 of the spider. The screen is secured to the rimV by a clamping ring 56 and serves to prevent excessive inward displacement of that portion of the diaphragm removed from the stop 40 and therefore 4further protects the diaphragm against rupture or shearing. A similar screen and stop may, of course, be provided adjacent ,theconcave surface of the diaphragm, for example, if it is desired to use a casing construction similar to that shown in Fig. 5. The screen should be of such mesh that the vibrations of the diaphragm and radiation of sound therefrom are not impeded.

y As shown in Fig. 7, the invention may be embodied in moving coil actuated loud speakers. In this embodiment a loud speaker may comprise a casing 57 having Aa shoulder portion 58 on which a permanenter electroinagnet 59 is mounted. A conical diaphragm 60 has its periphery connected to a flange 61 on the magnet by a iiexible annulus 62 and carries a frame or cylindrical support 63. A driving coil 6A is mounted on the support 68 and is disposed in an air gap formed by the pole pieces 65 and 66 of the magnet 59. A grille 67 having a screen 68 thereon is secured Within the shoulder portion 58 by a split ring 69. A pair of stop members 70 and 7l are disposed one adjacent each surface of the diaphragm 60 at thev apex thereof. The stop 7 O is provided with a threaded shank 72 which extends through internally threaded inserts 73 in the magnet 59, and has mounted thereon a look nut 7 4. The stop 7l is provided with a threaded shank 75 which is adjustably secured to the grille 67 by nuts 76 and 77. Adjustment of the spacing of the stops with reference to the diaphragm may be effected in the same manner as in the electromagnetic loud speakers hereinbefore described. f

In order to prevent standing waves to th rear of the diaphragm and to prevent resonance effects, a sound absorbing material 78, such as felt, may be provided between the diaphragm and the casing, as shown in Fig. 2. The material is preferably encased in a moisture-proof covering 79, such as rubberized fabric, to prevent absorption of any moisture which may be present in the casing. v

An impervious cover 8O may also be provided to protect the interior unit of the loud speaker during shipment and'against the action of the elements when mounted in position. The cover 8O is secured to the casing by bolts 81 passing through slots 82 in the cover plate, and wing nuts 83. A bolt 84 is pivoted upon an extension 85 of the casing l0 so that the cover may be swung through approximately 180 to the position shown in dot-ted outline in Fig. 2. In the'latter position, the bolt 84 is disposed in a slot 86 in a projecting arm 87 on the casing 10. 'A Wing nut 88 on the bolt 84 bears -againstthe plate 8O through the intermediary of a compression washer 8S). .The Vcom-pression washer ,is

sufficiently resilient so that when the plate is rotated to the position shown in dotted outline in Fig. 2 it is automatically clamped to the extension 87. 4

Although the invention has been disclosed and described with particular reference to loud speakers embodying conical diaphragms, it may of course, be applied equally well to devices having diaphragme of other. forms and also to transmitters. Numerous modiiications, furthermore, may be made in the specific structures shown and described without departing from the scope and spirit of the invention as defined inthe appended claims. l

VJ hat is claimed is l. A sound translating device comprising alarge direct-acting diaphragm, an actuatingunit, a member connecting said dia phragm and said unit,`and a stop member adjacent said diaphragm and extending outwardly from the point of attachment of. said member aiidsaid diaphragm.V

2. A sound translating device comprising a iiexibly supported, large direct-acting conoidal diaphragm, actuating means connected to the apex of said diaphragm, and a-stop member vadjacent said apex and conforming to a portion of the diaphragm surfacefor limiting the displacement thereof.

3. A sound translating device comprising a diaphragm, means including a vibratile armature for actuating the diaphragm, a connecting member between said armature and said diaphragm, and a stop member adjacent said diaphragm at the point of attachment of said connecting member and said diaphragm, said sto-p member being spaced from said diaphragm a distance substantially. equalto the maximum displacement of said armature from its neutral position.

t. A sound translating device comprising a large direct-acting conical diaphragm, an actuating unit including a vibratile armature, a connecting rod between said armature and the apex of said diaphragm, and a conical stop member adjacent said apex and spaced from said diaphragm a distance substantially equal to the maximum move kment ofsaid connecting rod.

point in its surface, and a pair of juxtaposed CFL "stop members on opposite sides of said diaphragm and adjacent said point.

'7. A sound translating device comprising a large direct-acting conical diaphragm, actuating means connected to said diaphragm at its apex,'anda -pair of conical. stop members disposed on opposite sides of said diaphragm adjacent said apex.

8. A sound translating device comprising alarge direct-acting diaphragm, an actuating. unit including ay vibratile armature, a

a large direct acting conical diaphragm,'av

rigid conical'stop member adjacent the apex ofsaid diaphragm, and a screen adjacentl said diaphragm extending between said stop member and the periphery of said diapliragm.

lO. A sound translating device comprising a support, a large direct-acting conical diaphragm having its periphery connected to said support, an actuating unit mounted 'on said support and connected to the apex of said diaphragm, a perforated conical stop member adjacent said apex, an adjustable connection between said stop member and said actuating unit, and a screen secured to saidv stop memberv and to said support a'kdjacent the periphery of said diaphragm.y

l1. A sound translating device comprising a diaphragm, an actuating means includingv a rod extending through said diaphragm,a

collar oneach side of said diaphragm secuied to said rod, and a disc of heat insulating material betiveeiieach collar andsaidv dial2. Asound translating device comprising a Water-tight-casing having an opening in the front thereof, a support in said casing having an annular portion seated in lsaid opening', a large direct-acting diaphragm 4of moisture-proof material substantially closing said opening, an aniiulus of moistureproof material connecting the periphery of said diaphragm and said annular portion of said support, and an actuating unit for said diaphragm mounted on said support Within said` casing.

In Witness Whereof,`I hereunto subscribe my name this 5th day of February 1932.

GEORGE E. ATKIN S.

Eioo

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