US 3757890 A
In a preferred embodiment, an electromagnetic audio speaker device including an electromagnetic vibrator connected functionally to a speaker cone, the vibrator and cone being suspended within an inner enclosure having a first speaker opening circumscribing a membrane means attached at the first inner opening periphery and attached to an outer periphery of the cone, the inner enclosure being encased within and spaced from an outer enclosure having a second speaker opening aligned with the first speaker opening, the inner and outer enclosures at their opening peripheries being joined to the outer periphery of the membrane means, the membrane means being an elastomer foam encased between two taut polyethylene membranes, the enclosures each being of plastic sheet material laminated to fiber-board sheet material.
Description (OCR text may contain errors)
United States Patent [191 Dunning Sept. 11, 1973  lnventor: William S. Dunning, 72-89 Yellowstone Blvd., Forest Hills, N.Y. 11375 221 Filed: Feb. 14,1972
211 Appl. No.2 225,797
Primary Examiner-Stephen}. Tomsky Attorney-William T. l-lough and L a forest S. Saulsbury 57 ABSTRACT In a preferred embodiment, an electromagnetic audio speaker device including an electromagnetic vibrator connected functionally to a speaker cone, the vibrator and cone being suspended within an inner enclosure having a first speaker opening circumscribing a membrane means attached at the first inner opening periphery and attached to an outer periphery of the cone, the inner enclosure being encased within and spaced from an outer enclosure having a second speaker opening aligned with the first speaker opening, the inner and outer enclosures at their opening peripheries being joined to the outer periphery of the membrane means, the membrane means being an elastomer foam encased between two taut polyethylene membranes, the enclosures each being of plastic sheet material laminated to fiber-board sheet material.
1 12 Claims, 3 Drawing Figures 1 ELECTROMAGNETIC SUSPENDED SPEAKER BACKGROUND TO THE INVENTION Prior to the present invention, the Applicants own abovenoted patents represent the sole relevant prior art existing over which the present invention is in particular an improvement, except that for all types of existing speakers it is desirable to improve the quality of reproduction especially of each of high and low frequency sounds which rarely are reproduceable by a single speaker with any reasonable degree of accuracy and quality. It should be additionally noted however that US. Pat. No. 3,424,873 discloses an embodiment having a liquid encompassed between two loosely supporting membranes; the rigid support of the electromagnet end of the cone, and the loose state of support of the wide end of the cone as well as the employment of vibration transmitting liquid each serves to defeat one or more objects of the present invention described hereafter.
SUMMARY OF THE INVENTION Accordingly it is an object of the present invention to obtain a speaker unit solving the above-type problems and difficulties.
Another object of the present invention is to eliminate structure of former cabinets not necessary when the present invention is utilized.
Another object is to further improve sound quality and reduce interferences such as resonance by preferred cabinet structure and composition together with improvements noted in the preceding objects.
Other objects become apparent from the preceding and following disclosure.
One or more of the preceding objects are obtained by the invention as defined hereafter.
The invention broadly encompasses an electromagnetic speaker including the cone and electromagnet mounted for support thereof on a suspending membrane unit attached supportingly at the outer perimeter of the cone, with the membrane unit being mounted at its outer extremities at the periphery of a double-walled enclosing structure enclosing the cone, the doublewalled structure defining the space between the two walls and each of the enclosures of the double-walled structure having commonly aligned speaker-mounting openings across which the supporting membrane unit is suspended in a taut state. The major improvement of the present speaker system resides in the combination as described above, with the membrane unit being composed of a plurality of membranes each having opposite faces with an intermediate media between opposing faces of the plurality, typically there being two stretched-taut membranes of polyester having typically polyurethane foam encased firmly between the taut membranes preferably along the entire opposing faces of the membranes. However, it is within the scope of the invention to use any elastomeric material as the intermediate media, including not only foams and including not only typical elastomers but additionally encompassing the possible use of any material capable of cushioning the sandwiching membranes, such as encapsulated rubber, another polyester sheet, powder, or any other such suitable material.
The enclosure structures preferably are of laminated plastic sheet and cellulosic fiber-board sheets whereby resonance disturbances at difi'erent sound frequencies are substantially eliminated as a result of the plastic and the fiber-board having resonance at different frequencies which resonances are further reduced by virtue of the lamination of one to the other.
THE FIGURES FIG. 1 illustrates a perspective view of a loudspeaker assembly embodying the invention.
FIG. 2 illustrates a vertical enlarged central sectional view taken along lines 2-2 of FIG. 1.
FIG. 3 illustrates an enlarged in-part section as taken within the broken-lines of FIG. 2, disclosing in particular an embodiment in which an intermediate media is sandwiched between opposing faces of two membranous diaphragms, as well as in detail illustrating the mechanism of attachment of the inner and outer enclosures relative to the membrane unit and the cone structure supported by the membrane unit.
DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates the speaker assembly 5 including the outer enclosure structure 6, the exposed face 7a of the membrane unit 7, the securing annular washer (or disk) 8a anchoring the inner edge of the membrane unit to the cone 9 by anchor screws 10, and outer anchor structure 8b with anchor screws 80. Also viewable in part is the speaker electric cord 14.
FIG. 2 further illustrates the cabinet of FIG. 1 as a typical embodiment as taken along lines 2-2 of FIG. 1. In greater detail, there is illustrated the cabinet 6 including the outer cabinet structure enclosure 6 composed of plastic sheet 6a laminated to celluslosic fiberboard. Fiber glass sound-absorbing sheet 11b may be utilized alone or as illustrated laminated or otherwise attached to and/or spaced from typically a cellulosic fiberboard or other substantially rigid insulator sheet. Space 15 is defined between the inner enclosure structure 11 and the outer enclosure structure 6. The inner enclosure structure 11 joins the outer enclosure structure at a point adjacent the membrane unit 7. It of course also would be possible for the membrane unit to be anchored to both the inner enclosure structure 11 and/or the outer enclosure structure 6.
FIG. 2 also illustrates the cone 9, the cone support 12 having openings or apertures 13, and the electromagnet 16, as well as an in-part view of the electric cord 14. The electromagnet and the cone and cone support are located within the enclosed space 17. Within the dotted line rectangle is the portion of FIG. 2 represented in enlarged view in FIG. 3.
FIG. 3 in detail represents a more clear picture of the laminated enclosure structure 6 including sheets 6a and 6b 6a and 6b and the laminated enclosure structure 11 including 11a and 11b, as well as the cone support 12 with aperture 13 and the cone 9. More importantly however is disclosed a preferred embodiment of the membrane unit 7 composed of a synthetic membrane 7c such as polyester and 7a having sandwiched between polyurethane foam 7b. It should be noted that the sheets 7a and 7c are in a taut state and that the space therebetween is in a preferred embodiment herein illustrated substantially filled by the urethane foam 7b. Also clearly illustrated is a typical mechanism of mounting the membrane unit 7 by utilization of the annular member 8d and the annular member 8a utilizing screws and bolts such as screw 18 and screw 19a and bolt 19b.
Although solely polyurethane or other urethane foam has been mentioned, any suitable or desirable or conventional elastomeric material or other media such as already noted above may be utilized as the intermediate media. Additionally, other types of flexible or semiflexible supportive plastics may be utilized as the membranes 7a and 7c of any conventional or desirable type. Similarly, the types of plastic and/or fiberboard laminated together may be varied as long as they are within the described function thereof of having different resonances. Typically acrylic sheet or any other rigid or semi-rigid plastic may be utilized preferably in lamination with the fiberboard.
Although it is important that the speaker be suspended substantially as shown, it is within the scope and spirit of the invention that the electromagnet and- /or cone frame support may be itself or themselves supported in part by other nonrigid suspending media attached at other points than that disclosed. Typically, polyamide sail-cloth may replace polyester sail-cloth. The fiberboard preferably includes an outer layer of substantially firm sheet having attached to an innerface thereof a soft fiberboard sheet material of a soundabsorbing nature. Total sound absorbing sheet material, including the above-noted soft sheet and also the inner enclosure preferred fiberglass sheet 11b jointly range from about 1 inch to about 1% inches typically one-half inch and five-eights inch respectively. With reference to FIG. 3, as described in greater detail, there is disclosed the outer-frame sheet structures including polyester plastic first sheet 6a and cellulosic fiberboard second sheet 6b, and an inner-frame sheet(s) structure including the different, fiber glass third sheet 110 mounted onto above-noted sheet 6b by the illustrated bolt, and the third sheet 11c extends substantially spaced from the second sheet 6b and defining the enclosure space 17, and sheet 110 being laminated to and between fourth and fifth similar sheets 11a and 1111 each of cellulosic fiberboard, as particularly pointed out and claimed in the appended claims.
1. A loudspeaker assembly comprising in combina tion an electromagnetic loudspeaker including an electromagnet and a conical vibratory cone operatively connected to each other, the cone outer periphery abutting a membranous diaphragm means having inner and outer peripheral edges with the abutting being at about the peripheral inner edge, the membranous diaphragm means having an opening therein defined by said inner peripheral edge, a first enclosure structure enclosing said electromagnet and coneand including a speaker-mounting opening defined by first enclosure structure peripherally around said opening, said membranous diaphragm means outer edge being attached to and supported by said first enclosure speaker-openingdefining structure with said diaphragm means mounted in a substantially taut state, the diaphragm means comprising a plurality of supportive membranous sheets each having front and back faces, the sheets being mounted in substantially parallel planes with one another, and an intermediate media sealed between and in contact with each of opposing ones of faces of said plurality.
2. A loudspeaker assembly of claim 1, in which said intermediate media comprises an elastomeric composition.
3. A loudspeaker assembly of claim 2, in which said elastomeric composition comprises substantially polyurethane foam.
4. A loudspeaker assembly of claim 3, in which said enclosure structure comprises laminated plastic sheet and cellulosic fiber-board sheet, and sound-absorbing insulation mounted within said enclosure and spaced from said cone.
5. A loudspeaker assembly of claim 1, in which said plurality comprises two opposing membranes separated by said intermediate media.
6. A loudspeaker assembly of claim 5, in which said opposing membranes are each flexible polyester membranes.
7. A loudspeaker assembly of claim 1, including a second enclosure having open-end structure defining a second opening arranged in alignment with said first speaker structure opening, said open-end structure of said second enclosure structure joining said peripheral outer edge and said second enclosure structure being mounted on and within the enclosing structure thereof spaced from the first enclosing structure at substantially all points such that an intermediate space is defined between the first enclosure structure and the second enclosure structure, in which said electromagnetic loudspeaker includes an apertured frame in supporting relationship with said electromagnet with the frame mounted on said diaphragm means inner periphery, and in which said cone is substantially conical.
8. A loudspeaker assembly of claim 1, including a second enclosure having open-end structure defining a second opening arranged in alignment with said first speaker structure opening, said open-end structure of said second'enclosure structure joining said peripheral outer edge and said second enclosure structure being mounted on and within the enclosing structure thereof spaced from the first enclosing structure at substantially points such that an intermediate space if is defined between the first enclosure structure and the second enclosure structure, in which said electromagnetic loudspeaker includes an apertured frame in supporting I relationship with said electromagnet with the frame mounted on said disphragm means inner periphery.
9. A loudspeaker cabinetlcomprising in combination a laminated enclosure structure defining an opening receivable of and mountable therein of an electromagnetic speaker cone and electromagnet means within an enclosure space defined by the enclosure structre, said laminated enclosure structure including an outer layer of a first sheet structure of first predetermined resonance properties having an inner face, a second layer of a second different sheet structure laminated to said inner face, said second sheet structure having an inner face and having second predetermined resonance properties different from said first sheet structure, a third different and substantially sound-absorbing sheet structure mounted about adjacent an inner side of and extending substantially spaced from said second sheets inner face and defining said enclosure space.
10. A loudspeaker cabinet of claim 9, in which said enclosing structure further includes a substantially sound-absorbing fourth sheet laminated on an outer and said fourth sheet structure in a face to face relationship.
12. The loudspeaker cabinet of claim 11, in which said first sheet structure comprises polyester plastic sheet, in which said second sheet structure comprises substantially hard cellulosic fiberboard sheet, in which said fourth and fifth sheet structures each comprise soft cellulosic fiberboard sheet, and in which said third structure comprises fiberglass.
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