US 2231479 A
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Feb. 11, 1941. s. v. PERRY SIGNAL TRANSLA'IING APPARATUS Filed Aug. 24, 1958 2 Sheets-Sheet l 3nnentor Sydney Perry dttorneg Feb. 11, 1941. s. v. PERRY 2,231,479
SIGNAL TRANSLATING APPARATUS Filed Aug. 24, 1958 2 Sheets-Sheet 2 PIPER a)? MET/1L 15 MET/IL RING 3 nnentor Sydney VPerry Gttorneg Patented Feb. 11, 1941 UNITED STATES SIGNAL TRANSLAT ING APPARATUS Sydney V. Perry, West Collingswood, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application August 24, 1938, Serial No. 226,446
This invention relates to signal translating apparatus, and more particularly to a dynamic loudspeaker of the multiple cone type.
Many attempts have been made heretofore to extend the frequency range over which loudspeakers of the aforementioned type will reproduce sound efficiently. For one reason or another, however, it has been found that systems heretofore proposed have been unsuccessful as a practical matter, and the primary object of my present invention is to provide an improved loudspeaker of this type in which the range of reproduction is considerably extended.
More specifically, it is an object of my present invention to provide an improved multiple cone dynamic loudspeaker in which the high frequency response particularly is increased.
It is also an object of my present invention to provide an improved loudspeaker as aforesaid which is simple in construction, which is highly efficient in use, which has a large power handling capacity, and which can be easily fabricated.
In accordance with my present invention, I provide the loudspeaker with two or more different-sized cones or diaphragms coupled to a common voice coil form through suitable compliances and also preferably coupled to each other by suitable compliances, the cones being arranged in concentric, nested relation. In addition, I load the small cone at a point near its apex end with a mass sufficient to cause resonance with the compliance of the parts between itself and the voice coil winding at a frequency near the high audio cut-off frequency. This greatly increases the response of the combination to the higher frequencies. The loading mass preferably takes the form of a metal cap of substantial area so that it, too, acts as a radiator to radiate sound energy, thereby further increasing the high frequency response.
The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with additional objects and advantages thereof, will best be understood from the following description of several embodiments thereof, when read in connection with the accompanying drawings, in which Figures 1 to 6, inclusive, are sectional views of several forms of loudspeaker assemblies according to my present invention, and
Figures '7 to 11, inclusive, are sectional views showing several modifications of loading caps or corresponding parts throughout, I have shown, 3
in Fig. 1, the vibratile system of a dynamic loudspeaker which comprises a relatively large conical diaphragm l adapted to particularly radiate the lower frequencies and a relatively small diaphragm 3 nested concentrically with the diaphragm l and adapted to particularly radiate the higher frequencies, the two diaphragms having a compliant connection 5 therebetween, as by means of an annular corrugation formed adjacent the edge of the diaphragm 3, or by thinning out an area adjacent the periphery of the diaphragm 3. The diaphragms I and 3 are also joined compliantly at their apex ends I and 8, respectively, and are cemented or otherwise suitably secured to one end of a voice coil form 9 which has inherent compliance in an axial direction and on which a voice coil H is wound through which signal currents may be passed. A suitable suspension l3 of well known form may be employed to support the system in proper relation to a suitable magnetic system (not shown) which supplies a magnetic field in which the voice coil H is located.
Secured to the small diaphragm 3 adjacent its apex end I is a cap member l5, preferably formed of metal, and having a central dome H and a reversely directed flange portion I9 by means of which the member l5 may be cemented to the diaphragm 3. In the modification shown in Fig. 1, the member I5 is so positioned that the bend Or edge 2| which is formed where the dome l1 and the flange l9 meet is in engagement with the adjacent end of the voice coil form 9, but it may also be so positioned that the edge 2| is preferably spaced somewhat from the coil form 9, as shown in Fig. 2. With this modification, most of the compliance occurs at or adjacent the apex ends I and 8. In any case, the surface area of the cap member I5 is quite substantial and sufficiently large to. radiate sound energy upon vibration thereof at frequencies Within the audible range, and the cap member 15 has a mass such that it will resonate with the combined compliance of all the elements between itself and the voice coil winding I I, at a frequency in the higher audio range. An arrangement of this sort will, I have found, greatly increase the response of the system to the higher frequencies.
The modification shown in Fig. 3 is generally similar to those previously described, but the voice coil form 9 is made somewhat longer and extends into the cone I. This permits spacing the two cones at their apex ends 1 and 8 and securing them at spaced points along the coil form 9. However, the small diaphragm is still loaded by the cap member I 5 and the relation that the mass of the cap member l5 resonates with the compliance of the parts between itself and the voice coil winding at a high audio frequency is still true.
In Fig. 4, the cone ends 1 and 8 are joined as in Fig. 1, but the cone I is provided with a compliance 23 near its end I. The modification of Fig. 5 is similar to that of Fig. 3 but resembles that of Fig. 4 as well by the inclusion of the compliance 23 in the cone I.
In Fig. 6, the voice coil form is made in three sections 9a, 9b and connected by compliant couplings 25 which provide the desired compliance in the coil form, the diaphragm 3 being connected to the section 9a, the diaphragm l to the section 9b, and the voice coil l I being wound on the section 90. Also, the diaphragms l and 3 are both provided with the compliances 23, and masses 2'? may be added to the cones I and 3 at desired points. The modification of Fig. 6 thus includes a large number of mechanical elements becoming, in effect, a multi-stage filter in which, by properly proportioning the various elements, it is possible to secure a desired shape of response curve.
Figs. '7 to 11 show various modifications of the cap member [5, that of Fig. 7 being similar to those previously described. The cap member l5 of Fig. 8 is provided with an additional mass 29 at its center, the mass 29 being, preferably, a solid block of wood, metal or the like. Such a cap member may be preferred for the system shown in 6.
In Fig. 9, the cap member I5 is not only provided with the additional mass .29, but is also formed with a corrugation or compliance 3|, while in Fig. 10, the mass 29 is omitted and the dome ii is formed with a plurality of corrugations or compliances 3!. Fig. 11 shows a composite cap member wherein the dome l l and the flange 29 are made of two separate pieces which are cemented together. The flange or ring I9 is preferably made of metal, and the central portion 51, which is cone-shaped, may be formed of paper, fiber, metal, or any other suitable material, it being essential only that its mass have the above-described relation to the compliance of the immediately associated parts of the vibrating system. The mass 29 of Figs. 8 and 9 and the center sections of the dome ll of Fig. 10 are each resonant with its associated compliance at some frequency at which minimum response is desired.
From the foregoing description, it will be apparent to those skiled in the art that I have provided an improved loudspeaker which is capale of reproducing signals over an extended range. Although I have shown and described several embodiments of my improved loudspeaker, it will, no doubt, be readily apparent to those skilled in the art that many other modifications thereof and changes in those shown and described are possible. For example, the masses 2? which are applied to the diaphragms I and 3 in Fig. 6 may also be applied to the modifications shown in Figs. 1 to 5, if desired. Many other changes and variations will, no doubt, also be apparent. I therefore desire that my invention shall not be limited except insofar as is made necessary by the prior art and by the spirit of the appended claims.
I claim as my invention:
1. In signal translating apparatus of the dy namic type, the combination of a movable system comprising a voice coil form, a plurality of diaphragms each having a compliant connection with said voice coil form, and a mass connected to one of said diaphragms, said mass being of such magnitude as to resonate with the compliance of a predetermined portion of said system at a predetermined frequency.
2. In signal translating apparatus of the dy namic'type, the combination of a movable system comprising a voice coil form having inherent compliance, a plurality of diaphragms each having a compliant connection with said voice coil form, and a mass connected to one of said diaphragms, said mass being of such magnitude as to resonate with the combined compliances of said voice coil form and said connections at a predetermined frequency.
3. In a loudspeaker of the dynamic type, the combination of a voice coil form having inherent compliance, a relatively large diaphragm, a relatively small diaphragm spaced from said large diaphragm, said diaphragms each having a compliant connection with said voice coil form, and a cap member connected to said small diaphragm, said member having a mass of such magnitude as to resonate with the combined compliances of said voice coil form and said connections at a predetermined frequency.
4. In a loudspeaker of the dynamic type, the combination of a voice coil form having inherent compliance, a relatively large conical diaphragm, a relatively small conical diaphragm concentrically arranged with respect to said large diaphragm, said diaphragms having a compliant connection therebetween and each of said diaphragms having also a compliant connection with said voice coil form, and a cap member connected to said small diaphragm adjacent its apex end, said member having a mass of such magnitude as to resonate with the compliance of said voice coil form and said second-named connections at a predetermined frequency.
5. The invention set forth in claim 4 characterized in that said cap member has a substantial surface whereby it is capable of radiating sound energy upon vibration thereof at a frequency within the audible range.
6. The invention set forth in claim 4 characterized in that said cap member is made of metal and characterized further in that said member has a surface sufficiently great to radiate sound energy upon vibration thereof at a frequency within the audible range.
'7. The invention set forth in claim .1 characterized by the addition of a mass secured to said cap member.
8. The invention set forth in claim 4 characterized in that said cap member is provided with at least one compliance therein.
9. The invention set forth in claim 4 characterized in that said cap member is provided with at least one compliance therein and characterized further by the addition of a mass secured to said cap member.
SYDNEY V. PERRY.