US2845135A - Auxiliary wave propagating and directing attachment for loudspeaker diaphragms - Google Patents

Description

y 29, 1958 A. B. COHEN ETAL 2,845,135

AUXILIARY WAVE PROPAGATING AND DIRECTING ATTACHMENT FOR LOUDSPEAKER DIAPHRAGMS Filed Sept. 26, 1955 4 Sheets-Sheet 1 1N VENTORS ATTORNEY July 29, 1958 A. B. COHEN ETAL AUXILIARY WAVE PROPAGATING AND DIRECTING ATTACHMENT '-.FOR LOUDSPEAKER DIAPHRAGMS 4 Sheets-Sheet 2 Filed Sept. 26, 1955 INVENTORS X M ATTORNEYS.

y 29, 1958 A. B. COHEN ETAL 2,845,135

AUXILIARY WAVE PROPAGATING AND omsc'rmc ATTACHMENT '"FOR LOUDSPEAKER DIAPHRAGMS 1 Filed Sept. 26, 1955 4 Sheets-Sheet 3 INVENTORS. 4-6- X I I ATTORNEYS y 9, 1958 A. B. COHEN ET AL 2,845,135

AUXILIARY WAVE PROPAGATING AND DIRECTING ATTACHMENT FOR LOUDSPEAKER DIAPHRAGMS 4 Sheets-Sheet 4 Filed Sept. 26, 1955 INVENTORS.

ATTORNEYS United States Patent i AUXILIARY WAVE PROPAGATING AND DIRECT- lNG ATTACHMENT FOR LOUDSPEAKER DIA- PHRAGMS Abraham B. Cohen, Bronx, and Sidney E. Levy, White Plains, N. Y.; said Cohen assignor, by mesne assignments, to Arthur Blumenfeld, New York, N. Y.

Application September 26, 1955, Serial No. 536,624

5 Claims. (Cl. 181-31) The present invention relates to attachments for loud-- speaker diaphragms, and more particularly to a novel attachment which is adapted to be associated with a loudspeaker diaphragm in such a manner and which is so constructed as to improve the mid-frequency and high frequency response of a loudspeaker embodying the invention.

Heretofore, loudspeaker diaphragms have been provided with supplemental or auxiliary sound diffusing attachments adapted to increase the spread or dispersion of the mid-frequency or high frequency sound waves generated by the diaphragm, wherein the attachments were in the form of transversely arched stiifeners of circular form. Such stiffeners were generally provided with apertures therethrough, whereby sound generated behind the stiffeners was diffused at the apertures and dispersed in all directions or concentrated and directed towards the axis of the path of sound travel.

In other previous types of loudspeakers, specially designed horns have been developed for producing more uniform dispersion of sound over the horizontally extended area in front of the speaker, while limiting vertical spread or dispersion of the sound waves.

The present invention contemplates as its primary objective combining in a sound reproducing structure the desirable characteristics of a diffuser and a special horn, both as above referred to, whereby the mid-frequency and high frequency response of a loudspeaker is improved.

Another object is to provide a conventional conical loudspeaker diaphragm with an auxiliary or supplementary sound propagating or diffusing attachment which is so constructed as to direct middle or high frequency sound waves generated adjacent to the apex or center of the diaphragm, or by the attachment itself, axially, while maintaining at a minimum sound radiation or dispersion in vertical directions, thus conserving signal energy which is utilized to expand horizontal sound radiation or dispersion.

The foregoing objective may be obtained by the utilization of a supplementary horn-like attachment which is so formed as to be capable of being attached to a conventional conical diaphragm adjacent to its center axis or adjacent to the usual voice coil bobbin with which such loudspeaker diaphragms are usually provided, and which is formed with side walls which flare laterally or horizontally to a larger extent than the top and bottom walls do vertically, and so that a substantially rectangular mouth is provided.

As will hereinafter appear, the supplementary horn-like attachment may be of a number of diflerent forms, and instead of having a rectangular mouth defined by lateral or vertical walls which are farther spaced apart than the top and bottom horizontal walls, the mouth may be square.

In addition, the flare or expansion of the horn-like attachment may be produced in various manners, as by the provision of relatively straight diverging walls, longi 'ice of divergence. In the latter case, the compound angle of divergence or expansion of the opposed walls of the attachment is preferably such that dispersion of sound Waves is predominantly in a vertical direction initially, but subsequently dispersion of the sound waves is predominantly in a horizontal direction, and during the subsequent stage of dispersion, the opposed top and bottom walls, in restricting vertical dispersion, build up pressure which increases the signal energy or amplitude in a horizontal direction.

A further object is to provide a sound reproducing assembly comprising a pair of coaxially arranged sound propagating elements adapted to be actuated or vibrated by a common voice coil to produce sound waves, one of said elements being so constructed as to generate midor high frequency sounds and being so configurated as to etfect dispersion of sounds generated thereby over a wide angle in one plane, while restricting such sound waves to limit the dispersion in a plane normal to the first-mentioned plane.

Other objects and advantages will be hereinafter described or will become apparent to those skilled in the art, and the novel features of the invention will be defined in the appended claims.

In the drawings:

Fig. 1 is a view in perspective, showing a loudspeaker diaphragm with one form of horn-like attachment mounted in assembled relation to the diaphragm in accordance with our invention;

Fig. 2 is a fragmentary plan view, showing another horn-like attachment somewhat similar to that of Fig. I mounted in assembled relation with a loudspeaker diaphragm;

Fig. 3 is a view in section, as taken on the line 33 of Fig. 2;

Fig. 4 is a view in section, as taken on the line 44 of Fig. 2;

Fig. 5 is a plan view of a modified form of horn-like attachment;

Fig. 6 is a view in section, as taken on the line 66 of Fig. 5;

Fig. 7 is a view in section, as taken on the line 77 of Fig. 5; and

Fig. 8 is a view in perspective, showing a further modified form of horn-like attachment mounted in assembled relation with a loudspeaker diaphragm.

Referring first to Figs. 1 through 4, 1 denotes a conventional cone-type loudspeaker diaphragm having an enlarged mouth bordered by a compliant corrugated marginal flange 2 adapted to be mounted on a suitable support (not shown). The diaphragm 1 tapers towards its end remote from the flange 2 and is provided with a central opening in which is adapted to be disposed the usual cylindrical voice coil support or bobbin 3 on which is disposed a voice coil winding 4. Bridging the end of the voice coil bobbin 3 in a conventional manner to provide a dust cap or closure to preclude the passage of dust or the like through the bobbin into the area behind the diaphragm, is a domed closure 5 which is preferably formed integrally on the bobbin 3.

All of the parts above described are conventional, and ordinarily the apex or small end of the diaphragm 1 would be attached, as by cementing, to the outer periphery of the bobbin 3, and therefore, the diaphragm is shown as having thereon a short axially extended flange 6 at its apex end which would enable attachment of the dia phragm 1 to the voice coil bobbin 3. However, in the illustrative embodiment of the present invention, an attachment tab or flange 7 of a horn-like attachment generally designated 8 is interposed between the bobbin 3 and diaphragm flange 6, and these elements are prefera- 3 bly secured together in an assembly as by cementing or the like.

The attachment 8, as seen in Figs. 1 through 4, has a pair of opposed longitudinally extended straight lateral walls 9, 9 which diverge away from the flange 7 and are generally arcuate in cross section. At the outer or forward end of the walls 9, they are each turned radially outwardly to form a flange 10, each flange 10 being corrugated so as to form a compliant section 11. Outwardly of the compliant sections 11, each flange 10 preferably has a section 12 projecting towards the diaphragm 1 and having a terminal tab 13 for attachment as by cementing to the diaphragm.

Intereonnecting the lateral walls 9 of the horn-like attachment 8, is a pair of opposed top and bottom walls 14, 14, each of which is transversely arched where it merges with the flange 7, these walls 14 diverging away from the flange 7, with the arch in each wall 14 progressively enlarging until the wall becomes flat at its forward extremity and terminates in planar relation with the lateral walls 9. The forward extremity of each wall 14 is preferably turned outwardly and back upon itself to form a reinforcingbead 15 which preferably merges and blends with the initial corrugation of compliant sections 11 of lateral walls 9.

Accordingly, it will be seen that the attachment has at its so-called rear end a circular central opening 16 defined by the flange or tab 7, and the opposed walls 9 and 14 diverge away from the opening 16 to form the hornlike member. Preferably, the angle of divergence of the lateral walls 9 is larger than the angle of divergence of the opposed top and bottom walls, so that a generally rectangular mouth is provided, said mouth having a greater lateral extent than its vertical extent, as best seen in Figs. 1 and 2.

In addition, the angular relation of the walls 9 and 14 is such that the progressive internal expansion or flare of the horn-like attachment 8 is in accordance with one of the conventional exponential rates which may be readily determined by the use of any well-known formula for determining the flare or expansion factor of loudspeaker horns.

As illustrated in Fig. 1, the flange 10 on each lateral wall 9 of the attachment 8 is preferably provided with a plurality of longitudinally extended openings 17 disposed in side-by-side laterally spaced relation. Therefore, in operation of the sound reproducing assembly, sound waves generated by diaphragm 1 behind the flanges 10 will not be trapped or reflected, but will pass through the respective openings 17 and be dispersed in wavelets emanating from each opening.

Moreover, the form of the horn-like attachment 8 will cause midand high frequency sound waves generated thereby or at the rear end of the assembly to be directed primarily in a wide horizontal area in front of the assembly, while limiting vertical spread or dispersion of such midand high frequency sounds. While in this specific illustrative embodiment, the horn-like attachment 8 is shown as secured to the outer periphery of the voice coil bobbin 3, it should be understood that the rear end of the attachment 8 may be secured at other points without departing from the invention, as on the domed cap of the bobbin 3 or on the body of diaphragm 1 at a position forwardly spaced from the bobbin 3.

Referring to Figs. 5, 6 and 7, there is shown a slightly modiliedform of horn-like attachment generally designated 8'. In this modified form, the body of the attachment, instead of having relatively straight divergent walls, is formed so as to be arched longitudinally,thus flaring on a curve. While at the small or rear end 7', the horn-like attachment 8' is annular in cross section, vertical expansion of the attachment 8' is progressively less than lateral expansion of the attachment as the continuous walls of the body thereof approach the forward end of the attachment, and therefore, the cross-sectional form of the horn changes from an annular or circular form through a progressively lengthening elliptical form, until the forward extremity of the attachment is reached. Preferably, at its forward extremity, the horn-like attachment 8 has its upper and lower margins straight and provided with a reinforcing bead 15', while the lateral sides of the attachment 8 are arcuate in cross section at the forward extremity and are provided with compliant attaching flanges 10' as previously described in connection with Figs. 1 through 4.

Where applicable, primed reference numerals corresponding to those used in Figs. 1 through 4 are applied to Figs. 5, 6 and 7 to designate corresponding or equivalent parts, and therefore, the remaining details of th horn-like attachment 8 need not be further described.

It should be understood, that the horn-like attachment 8', if desired, may also be provided with a plurality of longitudinally extended openings such as those designated 17 in Fig. 1.

Referring now to Fig. 8, there is illustrated a further modified horn-like attachment generally designated 8" which is adapted to be connected with a diaphragm 1" in the same manner as has been previously described. The illustrative attachment 8" is shown as having opposed side wall-s 9", 9" and opposed top and bottom walls 14', 14", but instead of having attaching flanges only atthe lateral ends of the rectangular mouth of the attachment 8", the mouth is provided with a compliant flange portion 11" extending about the entire forward extremity of the attachment 8", and a portion 12" extending from the compliant portion 11" towards the diaphragm 1" completely about the attachment 8", the latter portion having a marginal edge 13 adapted to be cemented to the diaphragm 1". In addition, the flange portion 12 is preferably provided with spaced openings 17" disposed in side by side relation about the entire flange, as is clearly illustrated.

The body of attachment 8", in lieu of the form shown in Fig. 8, may alternately have the form of Figs. 5, 6 and 7, as should be apparent.

The respective horn-like attachments herein disclosed are preferably fabricated of paper of a fibrous character capable of being molded, but these attachments maybe made of other materials without departing from the spirit of the invention, such as thin plastic, aluminum, or other suitable materials which are light in weight and have suffioient rigidity to maintain their form without distortion under vibration. A

Other changes and alterations may be made without departing from the spirit of the invention as defined in the appended claims.

We claim:

1. In a sound reproducing device including a vibratory diaphragm and a longitudinally extendal shorn-like attachment mounted coaxially with relation to said-diaphragm and connected thereto for vibration therewith,

said attachment having a small end and a large end'and progressively expanding in cross-sectional area from the small end to the large end, that improvement wherein the horn-like attachment expands in one plane at a greater angle than in a plane normal to the first-mentioned plane, and said horn-like attachment having a flange at its large end projecting into engagement with said diaphragm and secured to said diaphragm, said flange having a compliant section interposed between the diaphragm and themain body of the attachment.

2. In a sound reproducing device including a vibratory diaphragm and a longitudinally extended horn-like attachment mounted coaxially with relation to said diaphragm and connected thereto for vibration therewith, said attachment having a small end and a large end and progressively expanding in cross-sectional area from the small end to the large end, that improvement wherein the horn-like attachment expands in one plane at a greater angle than in a plane normal to the first-mentioned plane, and said horn-like attachment having a flange at its large end projecting into engagement with said diaphragm and secured to said diaphragm, said flange having a plurality of sound diffusing openings therein for liberating and diffusing sound waves generated by said diaphragm behind said flange.

3. In a sound reproducing device including a vibratory diaphragm and a longitudinally extended horn-like attachment mounted coaxially with relation to said diaphragm and connected thereto for vibration therewith, said attachment having a small end and a large end and progressively expanding in cross-sectional area from the small end to the large end, that improvement wherein the horn-like attachment expands in one plane at a greater angle than in a plane normal to the first-mentioned plane, and said hornlike attachment having a flange at its large end projecting into engagement with said diaphragm and secured to said diaphragm, said flange having a plurality of sound diffusing openings therein for liberating and diffusing sound waves generated by said diaphragm behind said flange, and said flange extending completely about the periphery of the large end of said horn-like attachment.

4. An attachment for vibratory loudspeaker diaphragm assemblies, comprising a longitudinally extended hornlike member having one end adapted to be connected to the diaphragm assembly for vibration therewith, said member expanding in cross-sectional area towards its opposite end and having a generally rectangular mouth, and said member having a laterally projecting flange adjacent its mouth and adapted to be secured to the diaphragm aforesaid, said flange having a compliant portion adjacent to the point of attachment of the flange to the diaphragm,

5. An attachment for vibratory loudspeaker diaphragm assemblies, comprising a longitudinally extended hornlike member having one end adapted to be connected to the diaphragm assembly for vibration therewith, said member expanding in cross-sectional area toward its opposite end and having a generally rectangular mouth, and said member having a laterally projecting flange adjacent its mouth and adapted to be secured to the diaphragm aforesaid, said flange having a plurality of sound difiusing openings therethrough.

References Cited in the file of this patent UNITED STATES PATENTS 1,984,542 Olson Dec. 18, 1934 2,565,069 Engholm Aug. 21, 1951 2,568,883 Carrington Sept. 25, 1951 2,641,329 Levy et a1. June 9, 1953 2,685,935 Lenz Aug. 10, 1954

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