US2755343A - Blast-proof and submergence-proof sound reproducing device - Google Patents

Description

S. E. LEVY July 17, 1956 BLAST-PROOF AND SUBMERGEINCE-PROOF SOUND REPRODUCING DEVICE Filed Oct. 5 1951 2 Sheets-Sheet 1 FIG. 1.

m w m 1/ S. E. LEVY July 17, 1956 BLAST-PROOF AND SUBMERGENCE-PROOF SOUND REPRODUCING DEVICE 2 Sheets-Sheet 2 Filed Oct. 5, 1951 INVENTOR BLAST-PROOF AND SUBMERGENCE-PROOF SOUND REPRODUCING DEVICE Sidney E. Levy, White Plains, N. Y., assignor to University Loudspeakers, Iuc., White Plains, N. Y., a corporation of New York Application October 5, 1951, Serial No. 249,944

'16 Claims. (Cl. 179-1155) The present invention relates to acoustic devices for reproducing sound, and more particularly, to an improved loud speaker which is so constructed as to be adaptable to uses either indoors or outdoors, including maritime and even under water uses, as well as military or other comparable uses where the device is subject to sudden and heavy shock waves, concussions, and/ or other variations of pressure, either rapid or gradual, which may be encountered as the result of explosions, gun-blasts, variations in altitude, variations in water pressure at different depths of water, and the like.

It is essential in sound reproducing devices of this type that moisture or Water be excluded from the usual magnetic structure which ordinarily defines a small air gap in which a voice coil is disposed. When used under adverse weather conditions or under Water, accumulations of moisture, water or other deposits borne thereby, in the magnetic structure or in the zone of the voice coil, would tend to interfere with the sound reproduction, and this would be particularly true if water becomes trapped in the structure.

It is accordingly one of the primary objects of this invention to provide an improved loud speaker assembly which effectively seals the magnetic structure, including the air gap and voice coil, against the entrance of moisture or water therein, both when the loud speaker is used under ordinary atmospheric conditions, as well as when submerged in water, even to great depths where the water pressure is very high.

In carrying out the aforementioned object, I have provided an improved, simple and highly effective seal for the voice coil lead wires where they pass from the interior to the exterior of the loud speaker frame or basket, as is necessary to operatively connect the loud speaker to the usual circuit which operates the same.

A further object of the invention is to provide a loud speaker which is so constructed as to allow the usual diaphragm thereof to freely move through the excursion range required for normal use, while providing buffer or guard means for limiting or arresting both forward and rearward movements thereof beyond its normal capacity, or which would tend to rupture the same or otherwise damage the joints of the component parts thereof which are ordinarily cemented together.

Ancillary to this latter objective, the diaphragm is preferably provided with suitable means for diverting and directing concussion or other extreme shock waves or pressures, outward beyond the weak area of the diaphragm, which is usually at or near the center thereof, said means preferably having the form of a convex bridge or stiffener member attached at its marginal edge to the diaphragm in radially outwardly spaced relation to and beyond the Zone of attachment of the voice coil or alternatively, said means having the form of a reinforcing patch or lamination which is preferably attached to the diaphragm in surface contact therewith over the entire weak area thereof.

Another objective of the invention is to provide an 2,755,343 Patented July 17, 1956 improved frame or basket for loud speakers, wherein the frame is provided with means for guiding and pre-centering the pot or magnet structure or assembly as it is assembled therein, whereby to prevent damage to or distortion of the voice coil as the voice coil enters the air gap of the magnet assembly, and further assuring accurate centering of the voice coil in the air gap when the magnet assembly assumes its final mounted position in the frame or basket.

Other and further objects and advantages of the invention will be hereinafter described and the novel features thereof defined in the appended claims.

In the drawings:

Fig. 1 is a sectional view as taken through one form of loud speaker constructed in accordance with the present invention, and representing a section on theline 11 of Fig. 3;

Fig. 2 is a fragmentary detail sectional view on a somewhat reduced scale, as taken on the line Z2 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is a sectional view as taken on the line 3-3 of Fig. 1, behind the diaphragm, and with a portion of the rear buffer or guard broken away;

Fig. 4 is a fragmentary sectional view showing a modified construction embodying an arched stiffener for strengthening and protecting the central portion of the diaphragm; and

Fig. 5 is another fragmentary sectional view showing a further modified construction embodying a different type of stiffener or protector for the central portion of the diaphragm.

Like reference characters designate corresponding parts in the several figures of the drawings, wherein it will be seen that the main parts of the loud speaker assembly include a generally circular basket or frame designated 1, a diaphragm 2 mounted on the forward end. of said frame, avoice coil 3 extended rearwardly from said diaphragm, a pot or magnet structure 4 seated and housed in the rear end of said frame, and a cover orclosure 5.

As best shown in Figures 1 and 3, the forward end of the basket orframe 1 is preferably provided with a radially outwardly extended rim orflange 6, which is shown in the drawings as being generally rectangular in outline, but which may be of any other shape as desired. This rim orflange 6 is preferably integrally connected by a plurality of ribs orwebs 7 ma generally circular body designated 8, said body having the form of a shell or housing in which the magnetic structure 4 is adapted to be enclosed. The ribs orwebs 7 extend rearwardly along the outer surface of thebody 8 to the extreme rear end thereof, where the body terminates in a radially outwardly extended circular flange 9, the cover orclosure member 5 being removably seated on and attached to said flange by a plurality of screws orother fasteners 10 extending through thecover 5, the flange 9, and preferably into the rear ends of the ribs orwebs 7. The forward marginal rim orflange 6, theribs 7, thebody 8, and the rear flange 9 are all preferably an integral basket or frame structure, as formed by a one-piece unitary casting of appropriate material such as aluminum, and as best shown in Figs. 1 and 3, it will be seen that there are large openings formed through the forward rim orflange 6 and between each pair ofadjacent ribs 7 around the outside of thehousing 3, as indicated at 11.

The front face of the forward rim orflange 6 is recessedI 3 apertures 14 formed therethrough, saidplate 13 constituting a rear buffer or guard for the diaphragm 2. Theplate 13 is preferably conical in shape, and the forward ends of theribs 7 which extend radially across the space between therim 6 and thehousing 8 are preferably inclined rearwardly at the same angle as the rear face of theplate 13 so that the latter plate bears flat against the forward ends of theribs 7 as well as bearing at its outer marginal edge against theannular shoulder 12.

Outwardly beyond the extreme marginal edge of thebuffer plate 13, therim 6 is preferably provided with a second recessedannular shoulder 15, and from this shoulder, a plurality of bosses or lugs are extended forwardly as indicated at 16, said bosses or lugs being arranged in equidistantly spaced relation to each other and serving to accurately center theperforated buffer plate 13 on theframe 1 at the forward end of the latter. By peening over or otherwise deforming thebosses 16, theplate 13 can be firmly attached to theframe 1 and positively held in an accurately centered position thereon.

A relatively largecentral opening 17 is provided in theplate 13, and the margin of this opening is preferably seated on a recessedannular shoulder 18 formed on the forward end of thehousing 8, and leaving a portion of the housing within this opening so that the forward end of the housing constitutes a continuation of theguard plate 13, as indicated at 19. The central portion of the forward end of thehousing 8 is provided with a relatively large opening 2%, the purpose of which will be hereinafter more fully described.

Mounted across the forward end of the frame orbasket 1, and disposed in forwardly spaced relation to the perforated buffer orguard plate 13 is the diaphragm 2, said diaphragm being formed of any suitable material, and being of conical form according to the embodiment illustrated in the drawings. The outer marginal edge of the diaphragm 2 is clamped or otherwise secured to therim 6 of the basket orframe 1, and a second perforated guard orbuffer plate 21 is disposed forwardly of the diaphragm in spaced relation thereto and is also clamped to therim 6 at its outer marginal edge. In their assembled positions, the two buffer orguard plates 13 and 21 are spaced from the diaphragm 2 at such a distance as not to interfere with the normal operation of the diaphragm, thereby allowing the diaphragm to move forwardly and rearwardly through the normal excursion range involved in the usual sound reproduction, but if the diaphragm is subjected to any abnormal movement in either a forward or rearward direction, as the result of a sudden shock wave caused by gun blasts, explosions, or otherwise, and which are usually accompanied by a sudden reduction in pressure, or as the result of changes in altitude, or changes in water pressure when the loud speaker is submerged, the guard orbuffer plates 13 and 21 will prevent any abnormal movements of the diaphragm tending to rupture or otherwise damage the same.

As best shown in Figure l, the diaphragm 2 is provided with a central opening, from the rear side of which there is extended a relatively short,cylindrical sleeve 22, this sleeve being cemented or otherwise suitably attached to a forwardly off-set portion 23 of acentering spider 24. Thisspider 24 is preferably formed in one-piece of suitable moisture-impervious material such as plastic. As clearly shown in the drawings, thespider 24 is radially extended outwardly from thecentral portion 23 thereof, and the outwardly extended portion is preferably provided with a plurality ofannular corrugations 25 or other compliant portions to allow complete freedom of forward and rearward movements thereof, along with the diaphragm 2, and to compensate for any substantial changes in pressure against the spider. Forward movements of thespider 24 are limited by the inner side of theportion 19 of the housing or frame which forms a continuation of theguard plate 13, the inner surface of thepart 19 being preferably suitably shaped as at 19 to conform with thecorrugations 25 on the radially extended portion of the spider but being normally spaced slightly therefrom to allow normal movements'bf the spider.

The spider is mounted in the bottom or forward end of an enlargedcavity 26 formed in thehousing 8 at the rear of the frame orbasket 1, with the outer marginal edge of the spider seating upon a fiat shoulder 26' at the base or forward end of the cavity. Also mounted in thecavity 26 is the pot or magnetic structure 4, the latter having any suitable form, but preferably being a unitary assembly consisting of an annularpermanent magnet 27, acentral core 28, a rear connectingplate 29 for connecting thepermanent magnet 27 and thecentral core 28 to gether, and an annular pole-piece 30 which defines a smallannular air gap 31 between the pole-piece 3G and thecentral core 23.

Cemented or otherwise attached to the interior of the forwardly projectingportion 23 of thespider 24 is a cylindrical sleeve ortube 32 which is extended rearwardly from thespider 24 and into theair gap 31 of the magnetic structure above referred to, said sleeve ortube 32, having thevoice coil 3 wound thereon and substantially centered in theair gap 31 when the magnetic unit 4 is fully assembled in the cavity of the frame orbasket 1.

In order to effectively seal the assembly against the entrance of moisture, water, or other foreign matter into the zone of thevoice coil 3 and the magnetic unit 4, there is preferably provided a pair of compliant, resilient gaskets respectively designated 33 and 34, arranged back-to-back in abutting contact with each other, and disposed between the forward end of the magnetic unit t and the rear face of the marginal edge of thespider 24. A separate cornpliant orresilient sealing gasket 35 is preferably interposed between the cover orclosure member 5 and the marginal flange 9 to which the cover is attached. Abowed spring member 36 is interposed between the rear end of the magnetic unit 4 and thecover 5, so that when thecover 5 is drawn up tight against the sealinggasket 35, by means of thescrew fastenings 10, the magnet unit 4 will be yieldingly urged forward against the sealinggaskets 33, 34, and towards thespider 24 so as to firmly clamp the outer marginal edge of the spider against the shoulder orseat 27 in the bottom or forward end of thecavity 26. Since the spider itself is moisture-impervious, moisture or water cannot pass through the spider or around the sealinggaskets 33, 34, into thecavity 26, but in the use of the loud speaker assembly under water, the pressure on opposite sides of the diaphragm 2 will be substantially equalized by reason of the fact that the water can freely enter through the perforated front buffer orguard plate 21 and thus contact the forward face of the diaphragm, while at the same time, water can freely enter through thespaces 11 in the basket orframe 1, and pass through the rear buffer orguard plate 13 so as to come into contact with the rear face of the diaphragm. Air pressures on the diaphragm are similarly equalized when the loud speaker is used at different altitudes. When the loud speaker is used outdoors under adverse weather conditions, or when used under water, the water will not remain trapped in the speaker at any point, due to the provision of a series ofdrain openings 36 formed in equi-distantly spaced relation to each other in the forward wall of thehousing 8, and an additional series of equi-distantly spaceddrain openings 37 through theforward rim 6 of the frame orbasket 1, as clearly shown in Figures 1 and 3.

In order to permit the usual lead wires orconductors 40 to be extended from thevoice coil 3 within the sealedcavity 26, through the frame to the exterior thereof where the lead wires can be connected to an operating circuit, theforward sealing gasket 33 is provided with a small opening therethrough, located midway between the inner and outer marginal edges of the gasket, there being one of these small openings for each lead wire, through which the lead wire can be extended. Each lead wire is preferably provided with a rubber or other resilient insulating covering which snugly fits the opening designated 38 in thegasket 33, and the portion of the lead wire which lies between the two gaskets will also be effectively clamped and sealed between thegasket 33 and thegasket 34, by the pressure of the magnet unit 4 against these gaskets, this pressure tending to force a portion of thegasket 33 surrounding the lead wire into anopening 39 provided through the frame orbasket 1, through which thelead wire 40 is extended to the exterior of the frame, Where its free end may be conveniently connected to aterminal 41 carried by aninsulating block 42 secured to the exterior of the frame orbasket 1, as by means of ascrew fastener 43 or the like. The opening 39 need not snugly embrace thelead wire 40, since pressure on thegasket 33 will effectively seal this opening by forcing the adjacent portion of the gasket partially into the inner end of theopening 39, as indicated at 44.

It will be noted from this construction, that the lead wires do not extend entirely across between the two sealinggaskets 33, 34, and therefore, there is no likelihood of water or moisture entering between the two gaskets by passing around the outer edges thereof, such as would otherwise occur if the lead wires were extended completely across both gaskets and then through the frame.

In assembling the magnetic unit 4 in the basket orframe 1, it is desirable to minimize or prevent any likelihood of damage or injury to thevoice coil 3, which is usually rather delicate, and it is also essential to accurately center the magnetic unit so that when it is fully assembled, thevoice coil 3 wil be substantially centered in the relatively smallannular air gap 31. To this end, the rear portion of the inner wall of thecavity 26 is enlarged, and then progressively tapers inwardly to a point near the base of thecavity 26. On this tapered portion of the cavity wall, there is preferably provided a plurality of. guide ribs or rails designated 45, these ribs serving to precenter the magnetic unit as it is moved forward into thecavity 26 during assembly thereof. Theribs 45 are equidistantly spaced apart, and any suitable number thereof from '3 or more can be used, although the preferred number ofribs 45 is 4 as illustrated. The forward ends of the ribs terminate flush with a continuouscylindrical wall 46 at the base of thecavity 26, thiscylindrical wall 46 being accurately sized or machined to snugly fit the cylindrical magnet assembly 4 and to accurately center the magnetic unit as it enters the base of thecavity 26, and as thevoice coil 3 begins to enter theair gap 31 during the assembly operation. By virtue of this arrangement, the machining operations on the frame orbasket 1 may be reduced to a minimum, since at most, it is only necessary to machine the relatively shortcylindrical wall 46 at the base of thecavity 26.

Referring to Figure 4, there is shown modified con struction wherein the central portion of the diaphragm 2, which is the weakest portion of the diaphragm, is provided with a reinforcing or stiffener member designated 47 of convex shape which is arched radially across the central axis of the diaphragm and bridges the central area thereof. The outer marginal edge 58 of thestifiener member 47 is suitably secured to the diaphragm, as by cementing the same thereto, at a distance somewhat beyond the zone of thevoice coil 3, whereby to direct and divert any pressure exerted there against, such as would be produced by gun-blasts, concussions, and the like, outwardly beyond the weak central area of the diaphragm, where the diaphragm is better able to withstand such pressures because of the presence of therear buffer plate 13 and the adjacent parts of the basket orframe 1 which serve to limit or arrest the rearward movement of the diaphragm under abnormal pressure conditions. When the diaphragm 2 is equipped with a stiffener such as shown in Figure 4, the forward buffer orguard plate 21 is preferably correspondingly arched as at 49 to generally conform to the shape of thestiffener 47 from which the stiffener is normally spaced so that it will not interfere with the sound reproducing movements of the diaphragm 2. Otherwise, the construction shown in Figure 4 is identical with that shown in Figures 1 to 3 inclusive.

Figure 5 shows still another modified construction, wherein a stiffener having the form of a concave patch 56 is secured to the central portion of the diaphragm 2 in the manner of a lamination, and with the reinforcingpatch 50 engaging the diaphragm 2 throughout the central portion thereof in surface contact therewith over an area extending substantially outwardly beyond the zone of thevoice coil 3. In this construction, the forward buffer orguard plate 21 is substantially the same as in the construction first described, and otherwise, the construction generally conforms to that disclosed in Figures 1 to 3 inclusive.

While the specific details have been herein shown and described, it is to be understood that the invention is not confined thereto as changes and alterations may be made without departing from the spirit thereof as defined by the appended claims.

I claim:

1. An acoustic device of the class described, comprising a frame, a diaphragm having its outer marginal edge mounted on said frame but otherwise said diaphragm being spaced from said frame for sound-reproducing movements, a voice coil connected to the central portion of said diaphragm and projecting coaxially therefrom within said frame, a magnetic structure mounted within said frame and defining an air gap in which the voice coil aforesaid is disposed, said frame having means for permitting the free flow of water, air and the like into and out of the frame at both sides of said diaphragm, and means for sealing said frame against the entrance of moisture, water and the like, into the zone of the voice coil, air gap and the magnetic structure, said sealing means including a moisture-impervious spider attached to said diaphragm and extended transversely across one end of said frame between said diaphragm on one side thereof and the Voice coil, air gap and magnetic structure on the opposite side thereof.

2. An acoustic device of the class described, comprising a frame, a diaphragm having its outer marginal edge wanted on said frame but otherwise said diaphragm being spaced from said frame for sound-reproducing movements, a voice coil connected to the central portion of said diaphragm and projecting coaxially therefrom within said frame, a magnetic structure mounted within said frame and defining an air gap in which the voice coil aforesaid is disposed, said frame having means for permitting the free fiow of water, air and the like into and out of the frame at both sides of said diaphragm, means for sealing said frame against the entrance of moisture, water and the like, into the zone of the voice coil, air gap and the magnetic structure, said sealing means including a moisture-impervious spider attached to said diaphragmand extended transversely across one end of said frame between said diaphragm on one side thereof and the voice coil, air gap and magnetic structure on the opposite side threof, said spider having its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a resilient sealing gasket interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, a removable closure member at tached to the end of said frame opposite to the diaphragm, and means interposed between said closure and said magnetic structure for maintaining said magnetic structure in sealing engagement with said sealing gasket.

3. An acoustic device of the class described, comprising a frame, a diaphragm having its outer marginal edge mounted on said frame but otherwise said diaphragm being spaced from said frame for sound-reproducing movements, a voice coil connected to the central portion of said diaphragm and projecting coaxially therefrom within said frame, a magnetic structure mounted within said extended transversely across one end of said frame be-' tween said diaphragm on one side thereof and the voice coil, air gap and magnetic structure on the opposite side thereof, said spider having its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a resilient sealing gasket interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, a removable closure member at tached to the end of said frame opposite to the diaphragm, and yieldable means between said closure member and said magnetic structure for urging said magnetic structure into firm sealing engagement with the sealing gasket aforesaid when the closure member is attached to said frame.

4. An acoustic device of the class described, comprising a frame, a diaphragm having its outer marginal edge mounted on said frame but otherwise said diaphragm being spaced from said frame for sound-reproducing movements, a voice coil connected to the central portion of said diaphragm and projecting coaxially therefrom within said frame, a magnetic structure mounted within said frame and defining an air gap in which the voice coil aforesaid is disposed, said frame having means for permitting the free flow of Water, air and the like into and out of the frame at both sides of said diaphragm, means for sealing said frame against the entrance of moisture, water and the like, into the zone of the voice coil, air gap and the magnetic structure, said sealing means including a moisture-impervious spider attached to said diaphragm and extended transversely across one end of said frame between said diaphragm on one side thereof and the voice coil, air gap and magnetic structure on the opposite side thereof, said spider having its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a resilient sealing gasket interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, a removable closure member attached to the end of said frame opposite to the diaphragm, yieldable means between said closure member and said magnetic structure for urging said magnetic structure into firm sealing engagement with the sealing gasket aforesaid When the closure member is attached to said frame, and a separate resilient sealing gasket interposed between said closure member and said frame.

5. An acoustic device as defined inclaim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a pair of resilient sealing gaskets disposed back-to-back in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frameaperture, to the exterior of said frame.

6. An acoustic device as defined inclaim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a pair of resilient sealing gaskets disposed back-to back in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frame aperture, to the exterior of said frame, said conductor lead snugly fitting at least the aperture in the apertured gasket and efiectively sealed therein by the other gasket and also sealed between the abutting gaskets when the latter are pressed together by the clamping action of the magnetic structure on said gaskets.

7. An acoustic device as defined inclaim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a pair of resilient sealing gaskets disposed back-toback in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frame aperture, to the exterior of said frame, said conductor lead snugly fitting at least the aperture in the apertured gasket and effectively sealed therein by the other gasket and also sealed between the abutting gaskets when the latter are pressed together by the clamping action of the magnetic structure on said gaskets, and means mounted on said frame in spaced relation to at leastone side of said diaphragm for limiting and arresting abnormal movements of said diaphragm inone direction.

8. An acoustic device as defined inclaim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and'said magnetic structure therein, with a pair of resilient sealing gaskets disposed back-toback in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frame aperture, to the exterior of said frame, said conductor lead snugly fitting at least the aperture in the apertured gasket and effectively sealed therein by the other gasket and also sealed between the abutting gaskets when the latter are pressed together by the clamping action of the magnetic structure on said gaskets, and means mounted on said frame in spaced relation to at least one side of said diaphragm for limiting and arresting abnormal movements of said diaphragm in one direction, said last-named means having the form of a buffer member disposed substantially parallel to and generally conforming to the contour of the main body of said diaphragm for surface contact therewith at least over the area thereof which lies radially outwardly beyond the voice coil.

9. An acoustic device as defined in claim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a pair of resilient sealing gaskets disposed back-toback in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frame aperture, to the exterior of said frame, said conductor lead snugly fitting at least the aperture in the apertured gasket and effectively sealed therein by the other gasket and also sealed between the abutting gaskets when the latter are pressed together by the clamping action of the magnetic structure on said gaskets, and means mounted on said frame in spaced relation to at least one side of said diaphragm for limiting and arresting abnormal movements of said diaphragm in one direction, said last-named means having the form of a buffer member disposed substantially parallel to and generally conforming to the contour of the main body of said diaphragm for surface contact therewith at least over the area thereof which lies radially outwardly beyond the voice coil, said frame having means formed thereon for centering said buifer member relative to the frame.

10. An acoustic device as defined in claim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a pair of resilient sealing gaskets disposed back-to-back in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frame aperture, to the exterior of said frame, said conductor lead snugly fitting at least the aperture in the apertured gasket and effectively sealed therein by the other gasket and also sealed between the abutting gaskets when the latter are pressed together by the clamping action of the magnetic structure on said gaskets, and means mounted on said frame in spaced relation to at least one side of said diaphragm for limiting and arresting abnormal movements of said diaphragm in one direction, said last-named means having the form of a buffer member disposed substantially parallel to and generally conforming to the contour of the main body of said diaphragm for surface contact therewith at least over the area thereof which lies radially outwardly beyond the voice coil, said frame having means formed thereon and engaging the outer marginal edge of said buffer member for centering said buffer member relative to the frame.

11. An acoustic device as defined inclaim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and said magnetic structure therein,

with a pair of resilient sealing gaskets disposed back-toback in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frame aperture, to the exterior of said frame, said conductor lead snugly fitting at least the aperture in the apertured gasket and effectively sealed therein by the other gasket and also sealed between the abutting gaskets when the latter are pressed together by the clamping action of the magnetic structure on said gaskets, and means mounted on said frame in spaced relation to at least one side of said diaphragm for limiting and arresting abnormal movements of said diaphragm in one direction, said lastnamed means having the form of a buffer member disposed substantially parallel to and generally conforming to the contour of the main body of said diaphragm for surface contact therewith at least over the area thereof which lies radially outwardly beyond the voice coil, said frame having deformable means formed thereon for centering and securing said buffer member relative to the frame.

12. An acoustic device as defined in claim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a pair of resilient sealing gaskets disposed back-to back in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frame aperture, to the exterior of said frame, said conductor lead snugly fitting at least the'aperture in the apertured gasket and elfectively sealed therein by the other gasket and also sealed between the abutting gaskets when the latter are pressed together by the clamping action of the magnetic structure on said gaskets, means mounted on said frame in spaced relation to at least one side of said diaphragm for limiting and arresting abnormal movements of said diaphragm in one direction, said last-named means having the form of a buffer member disposed substantially parallel to and generally conforming to the contour of the main body of said diaphragm for surface contact therewith at least over the area thereof which lies radially outwardly beyond the 'voice coil, and means carried by the central portion of said diaphragm for stiffening the same and for directing and diverting-pressures acting upon said diaphragm towards that portion of said diaphragm which is engageable with said buffer member.

13. An acoustic device as defined in claim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a pair of resilient sealing gaskets disposed back-toback in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frame aperture, to the exterior of said frame, said conductor lead snugly fitting at least the aperture in the apertured gasket and effectively sealed'therein by the other-gasket and also sealed between the abutting gaskets when the latter are pressed together by the clamping action of the magnetic structure on said gaskets, means mounted on said frame in spaced relation to at least one side of said diaphragm for limiting and arresting abnormal movements of said diaphragm in one direction, said lastnamed means having the form of a buffer member disposed substantially parallel to and generally conforming to the contour of the main body of said diaphragm for surface contact therewith at least over the area thereof which lies radially outwardly beyond the voice coil, and means carried by the central portion of said diaphragm for stiffening the same and for directing and diverting pressures acting upon said diaphragm towards that portion of said diaphragm which is engageable with said buffer member, said stiffening means having the form of an arched bridge member transversely extended across the central portion of said diaphragm and secured at its outer marginal edge to said diaphragm.

14. An acoustic device as defined in claim 1, wherein said spider has its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a pair of resilient sealing gaskets disposed back-toback in abutting contact with each other and interposed between the marginal edge of said spider and the adjacent, end of said magnetic structure, one of said gaskets having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil and between said gaskets, and thence through the aperture aforesaid in one of said gaskets and through the registered frame aperture, to the exterior of said frame, said conductor lead snugly fitting at least the aperture in the apertured gasket and effectively sealed therein by the other gasket and also sealed between the abutting gaskets when the latter are pressed together by the clamping action of the magnetic structure on said gaskets, means mounted on said frame in spaced relation to at least one side of said diaphragm for limiting and arresting abnormal movements of said diaphragm in one direction, said last-named means having the form of a buffer member disposed substantially paralell to and generally conforming to the contour of the main body of said diaphragm for surface contact therewith at least over the area thereof which lies radially outwardly beyond the voice coil, and means carried by the central portion of said diaphragm for stiffening the same and for directing and diverting pressures acting upon said diaphragm towards that portion of said diaphragm which is engageable with said buffer member, said stiffening means having the form of a patch member having surface contact with said diaphragm substantially throughout the central portion of said diaphragm.

15. An acoustic device of the class described, comprising a frame, a diaphragm having its outer marginal edge mounted on said frame but otherwise said diaphragm being spaced from said frame for sound-reproducing movements, a voice coil connected to the central portion of said diaphragm and projecting coaxially therefrom within said frame, a magnetic structure mounted within said frame and defining an air gap in which the voice coil aforesaid is disposed, and means for sealing said frame against the entrance of moisture, Water and the like, into the zone of the voice coil, air gap and the magnetic structure, said sealing means including a moisture-impervious spider attached to said diaphragm and extended transversely across one end of said frame between said diaphragm on one side thereof and the voice coil, air gap and magnetic structure on the opposite side thereof, said spider having its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a resilient sealing gasket interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, said gasket having an aperture therein disposed in register with an aperture through the adjacent portion of said frame, and an electrical conductor lead extending from said voice coil through the aperture aforesaid in said gasket and through the registered frame aperture, to the exterior of said frame.

16. An acoustic device of the class described, comprising a frame, a diaphragm having its outer marginal edge mounted on said frame but otherwise said diaphragm being spaced from said frame for sound-reproducing movements, a voice coil connected to the central portion of said diaphragm and projecting coaxially therefrom Within said frame, a magnetic structure mounted within said frame and defining an air gap in which the voice coil aforesaid is disposed, and means for sealing said frame against the entrance of moisture, water and the like, into the zone of the voice coil, air gap and the magnetic structure, said sealing means including a moisture-impervious spider attached to said diaphragm and extended transversely across one end of said frame between said diaphragm on one side thereof and the voice coil, air gap and magnetic structure on the opposite side thereof, said spider having its outer marginal edge clamped firmly between said frame and said magnetic structure therein, with a resilient sealing gasket interposed between the marginal edge of said spider and the adjacent end of said magnetic structure, said frame having a lead wire aperture therein and extended to one face of the sealing gasket, an electrical conductor lead extending from the voice coil through the frame aperture to the exterior of said frame, and said sealing gasket being sufiiciently compressed between said frame and said magnetic structure and about the conductor lead aforesaid where the latter passes into the frame aperture, to effectively seal the conductor lead in the frame.

References Cited in the file of this patent UNITED STATES PATENTS 1,711,514 Abrahams et al May 7, 1929 2,037,187 Wente Apr. 14, 1936 2,293,078 Proctor Aug. 18, 1942 2,346,429 Harrison Apr. 11, 1944 2,404,360 Bostwick July 23, 1946 2,404,784 Bostwick July 30, 1946 2,404,785 Bostwick et al July 30, 1946 2,490,227 Murkman Dec. 6, 1949 2,517,138 Seabert Aug. 1, 1950 Engholm Oct. 10, 1950

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