US1793889A - Loud-speaker device - Google Patents

Description

Feb. 24, 1931. WOQD 1,793,889

LOUD SPEAKER DEVI CE Filed June 21, 1927 INVENTOR 3;} 7 By Afiorneys,

Patented Feb. 24, 1931 ANDREW F. W001), 013 JERSEY CITY, NEW JERSEY LOUD-SPEAKER DEVICE Application filed. June 21,

This invention relates particularly to a loud speaker or loud speaking telephone of the type in which sound is propagated from a vibrating suriac directly to the free air without the intervention of a horn, the usual cone type loud speaker b an example of this type of apparatus. Nevertheless, certain "Features of my conical diaphragm and the conical actuating means for transmitting motion to such diaphragm are appli able to any form of sound reproducer employing a vibrating diaphragm, either with or without a horn, and actuated by any source of vibrating energy, mechanical, electric or electromagnetic.

The object of the present invention is to provide a sound reproducing device which. to a high degree, faithfully reproduces a comparatively wide range of audible frequencies.

A further object of the invention is to provide a loud speaker device, which, for a given energy input, delivers an increased volume of sound.

The invention further contemplates in combination with a cone type diaphragm. a sounding board, against which the diaphragm actuating mechanism preferably rests, so that the reaction from the forces against the diaphragm will act upon said sounding board, and in the preferred con struction the invention provides a second sounding board spaced apart from said first mentioned sounding board to provide a resonant air space therebetween.

Another object of the invention is to provide a conical actuating element through which vibration is transmitted to a larger conical diaphragm at points removed from the apex of the latter. 7

The present invention to increase the efiiciency of the cone type loud speaker by the combination of two conical or dished diaphragms of somewhat different conical angles, whereby, although the members be connected together at a point, there will, nevertheless, be provided between them an. air space, the volume of which expands radially outward.

Another object is to provide a conical or 1927. Serial No. 200,379.

dished diaphragm, the marginal or basal edges of which are so shaped as to provide a plurality of areas which are not fully supported by the central conical area but extend th efrom, said areas therefore, being more ilei .ble than if they were connected by portions of the general conical surface.

Further objects oi the invention will be apparent from the following description, in which reference is had to the accompanying drawings, in which Figure l is an axial cross-section of loud speaker device having a double conical diaphragm and a conical actuating means for said diaphragm.

a plan view of a loud speaker construction to the device shown d 2, except that the diaphragms and instead of star- 1 Figs. 1 L v o 1 sounding boards are circinar shaped.

Figs. 4 and o are and central vertical cross-sec elv a plan view .11 of a modidished dia respect weaker h av! 11 tied form of lone. phragm.

Jigs. 6, 7 and 8 are plan views of dia- --ragms according to the present invention ng differentmarginal contours. Fig. 9 is an axial ross-section of a phonoraph reproducer employing a conical diahragm actuated through a smaller conical riaphra Fig. 10 shows a telephone receiver having a conical diaphragm actuating element.

Referring to the embodiment shown in Figs. 1 and 2, the loud speaking device comcated in dotted lines in Fig. 2. It will be 1 understood that these flexible portions comprising the points of the star-shaped diaphragnis are not flat, but to av considerable degree partake of the conical contour of the central portion of the diaphragm because they form a part of and extend therefrom;

This is desirable, because while a certain degree of flexibility in these areas greatly improves the quality of reproduction, nevertheless they must have a certain strength or rigidity in order to efiiciency propagate fibrous substance, such as paper, parchment I or very light wood, or the diaphragms may be made of thin aluminum sheets. In fact, any material that is light and relatively strong may be employed. The best results liave been obtained with stiff paper. I

The conical actuator 7 which is connected to the vibrating" member of the electromag netic unit,'is1 in itself a conical diaphragm, its basal edgesbeing'preferably flanged to provide an annulus 8 which is cemented to the inner or concave face of diaphragm 1. This arrangemen provides an enclosed air space 9 between the actuator and the diaphragm l which is believed to contribute a desirable resonance effect. An important advantage of this arrangement, however, is had through the application of the vibrating energy to the major diaphragm l at points removed from the apex thereof. The direct mechanical vibration from the electromagnetic unit transmitted through the conical actuator 7 to the major diaphragm 1 and acts directly upon such diaphragm through the annular connection. 8. This arrangement results in a more positive and effective action of the unit upon the diaphragm 1, so that the reproduced sound corresponds more closely to the applied vibrations than in diaphragms where such vibrations are applied at a single central point on the diaphragm.

Furthermore, the opposite disposition of the conical diaphragm and ts con cal actuator provides the additional advantage that when the actuator is moving to the left, and

consequently having its maximum. rigidity I through the inherent self-supporting effect of a conical surface, the diaphragm which it actuates, because of its'opposite conicity, is On the reverse movement, the

major diaphragm 1 is the more rigid and the coniealactuator less rigid because it does not receive the inherent bracing effect of a conical sheet being stressed to flatten or expand it, and thus a compensation is had which tends to render the opposing phases of any complete wave movement similar. The conical bracing effect referred to is due to the to destroy to a considerable extent its rigidity with respect to such force. For example, a para sol not latched in the open position will be found to strongly resist a force tending to open or flatten it beyond a certain point determined by its design. Nevertheless, a very slight force acting in the opposite direction will cause the collapse or folding up of the ara sol.

' The electromagnetic unit is preferably mount-ed directly upon the face of a sounding' board 15 so that the mechanical reaction of vibrating the conical diaphragms is transmitted to such sounding board; This sounding board may be of spruce or other suitable resonant material, and should be somewhat larger than the largest of the diaphragms mounted in front of it. The sounding board effect is further increased by mounting to the rear (or to the left, as shown in Fig. 1) of the sounding board 15, a second sounding board 16, .he two being spaced apart to provide resonating chamber 17 as shown. The

boards are connected together near their edges by pins 18, and when two sounding boards are employed, the one nearest the diaphragms is preferably fenestrated to provide openings 19 through which sound waves from the rear of the diphragins may pass directly to the resonance chamber 17. The

mounted on the rear of thesounding board 16, so that it may be hung against the wall, and this bracket, together with the small fittings 21, serve to hold the sounding board out of contact ith the wall so that it is free to vibrate over the greater part of its central area. The loud speaker devicelmay,of

course, be mounted uponv a pedestal. This pedestal comprises a weighted base 23 having an upright column 24, which is threaded into a socket 25 concealed between the two sounding boards. If it is desired to hang the loud speaker against the wall, the'pedestal is thus readily removed.

In certain types of electromagnetic units for-loud speaker diaphragms the actuating pin 6 is sufficiently rigid to permit of the mounting of one or more diaphragms there on, the diaphragms being supported solely by such pin. l/Vhere multiple diaphragms are to be employed, however, it is preferable toprovide other means of support, and such, support should be designed to provide the utmost freedom of movement for the'dia device is provided with a hanger bracket 20 phragm. To this end, according to the pres ent invention, the multiple diaphragm arrangement illustrated in Figure 1 is suspended upon a wire or other flexible member 26 from a b r 27 extending forwardly from the sounding boarc The flexible strand is preferably attached to the inner diaphragm 1, as means of a rivet 28 a point immediately above the center of gravity of the connected cones 1, 2 and '7. By this arrangement the actuating pin 6 is entirely relieved of the duty of supporting any part of the weight of the cones. The suspending wire may be adjust ably secured to the rod or post 27 by means of a set screw 28 which clamps the wire in any desired adjustment, the wire sliding free through the vertical bore 28 when the said screw is loosened.

In the preferred construction, rod 27 extends through the two sounding boards 15, 16, thus providing in a single element the spacing post 18 which maintains the sounding boards in proper relationship and also the support for the diaphragms. The por tion 18 of the rod 27 which lies between the two sounding boards is somewhat enlarged to provide shoulders against which the sounding boards are clamped. The rod is threadeo at either side of such enlarged portion, and the left-hand sounding board 1) is clamped in place by a nut 29; the righthand sounding board is held in place by means of the fitting 20 which is threaded onto the end of the rod, the said fitting providing the eye or other suitable means for hanging the loud speaker against the wall.

In Fig. 3 there is illustrated a loud speaker similar in every respect to the embodiment illustrated in Figs. 1 and 2, except that the diaphragms 1 and 2, and also the sounding boards 15, 16, are round instead of starshaped, such diaphragms therefore, being of the conventional cone type. While with sucn an arrangement the advantages due to the salient areas 4 and 4 of the star-shaped diaphragm are not had, nevertheless, the application of a conical actuator to a cone diaphragm of the usual type effects improve ment in the quality of reproduction in such loud speakers.

The combination of two conical diaphragms, the surfaces of which are inclined at different angles but in the same angular sense from transverse plane, will be found to favorably affect the quality of reproduction. While in the preferred construction the cones are directly connected together at their apexes, very satisfactory results can be had by combining two cones of similar shape and spacing them apart to provide an air chamber between them, the only absolute requirement as to the disposition of the cones being that their surfaces slope in the same sense, though not necessarily in the same degree, from a plane transverse to the conical axis,that is to say-the one cone, at least in part, projects within the second cone instead of the cones being arranged in opposition one to another as has hitherto characterized certain types of double cone loud speakers. It is not essential that super posed surfaces of the two cones diverge in the radial direction in order to provide an expanding tone chamber between them, because the volume of an annulus between the two cones at different radii will increase according to the squares of such radii, even though the cones be of similar taper or conical angle. Nevertheless, it is preferred to make the conical angle of the inner cone 1 somewhat more acute than that of the outer cone 2 so that a still further radial expansion is permitted.

In Figs. 4 to 8 inclusive are illustrated loud speaker devices according to the present invention, in which the principle of employing a conical or dished diaphragm having salients of various forms extending from the central conical or dished portion is shown The crevice illustrated in Figs. 4 and 5 com prises a dished diaphragm which is shieldshaped, the flexible salients being provided at the points 31 and 3:2. The diaphragm is lirectly actuated by the electromagnetic unit 33 at a point 3a, which coincides with what may be termed the axis of generation of the somewhat spherical form of thesurface. In this modification the actual form of the diaphragm surface is that of a cone, the apex of which has been rounded off, as indicated in Fig. 3. A dished diaphragm of this contour may be readily formed by radially.

slitting a conical diaphragm towards its cen ter and then pressing the segments thus formed into the desired rounded contour. This operation will cause the margins of the segments to overlap, and these overlapping margins 35 are cemented together. If ductile material is used for the diaphragm, it may, of course, be pressed or drawn into the dished form without cutting. The loud speaker unit 33 in this construction is mounted directly upon a sounding board 37 in the manner hereinbefore described. In the present instance only single sounding board is employed, this board oeing provided with a hanger ring 39 and posts 10, by means of which the sounding board, when hung against a wall, is held away therefrom to permit its free vibration and also to afford a resonant air space bet veen itself and the wall. diaphragm shown in Fig. 6 is a further modification in which salients 42, of greater flexibility, are formed by shaping the marginal edges of the conical surface to provide rela tively narrow projecting areas bounded by four similar arcs 43.

The diaphragm 45 illustrated in 7 pro videsin still another form flexible salients 4:6,

The

, acteristic is also present in the 47 and 48, the three types of salients each differing arena the other, so that the symmetry of the diaphragm with respect to a horizontal transverse Xis, is destroyed. This chardevice illustrated in Figs. 4 and 5 and results in a tendency to eliminate objectionable periodic defects-of the diaphragm."

The diaphragm illustrated in Fig. 8 is more properly described s pyramidal han conical, and its apex is asymmetrically disposed with respec to any possible that may be chosen. The basal edge of the diaphragm forms substantially a rec-tangle, the corner areas of which provide flexible salients 50,51, 52 and 5,3, which extend outward beyond the central pyramidal portion.

In Fig. 9 there is illustrated a phonograph reproducer employing a diaphragm 60, which is acted uponby a conical actuator 61, according to the; present invention. Mechanical vibrations are transmitted from the surface of the record through a stylus'bar 62 in the usual manner, but this stylus bar, instead of being attached directly to the diaphragm 60, is connected to the apex 63 of the conical actuator 61 The diaphragm is of conical form and may be made of thin aluminum sheet, the.

conical actuator being formed of the same material and having an annular flange 64s which is connected to the diaphragm. The

phragm 70, preferably formed of mica, is

employed. Cemented to the rear of this dia phragm is an actuating'cone 71, which may be made of parchment. The apex of this cone is flattened to receive an iron armature 72, which is acted upon the telephone electro magnets 73. Diaphragm 70 is flexibly mounted at its edges between suitable gaskets 74.

A telephone receiver of this type is very sensi-' tive. The mica diaphragm can be made relatively thin because it is greatly strengthened by the parchment cone 71, and the total vibrating mass of the diaphragm and actuating cone will be materially less than that of the usual iron diaphragm employed in telephone receivers. It will be seen that the principle of. imparting vibrating energy to the larger diaphragm through the actuating cone,

about an annulus removed to a considerable. extent from the center of such diaphragm, corresponds to the underlying prlnciple of phragms,

the loud speaker device illustrated in Figs. 1 and 2, but while small diaphragms such as are employed in telephone receivers, give very good results when made flat, in the large diaphragms necessarily employed in loud speakers, wheresuch diaphragms act directly upon unconfined air, the conical form of diaphragm is to be preferred.

While various embodiments and modifications of my invention have been hereinbefore described and illustrated, it is to be understood that these are merely illustrative and that the i vention may be otherwise variously modified and embodied without departing from the spirit thereof, as set forth in the following claims.

W hat 1' claim is:

l. A sound reproducer comprising a substantially conical main diaphragm, a smaller opposed actuator diaphragm basally connected thereto in such manner as to provide substantially enclosed. air chamber therebetween, and actuating means adapted to apply vibrations to said diaphragm through said actuator diaphragm, said. main diaphragm having a total area at least twice as great, as the area of said actuator diaphragm.

' 2. A sound reproducer comprising a substantially conical diaphragm and a hollow conical actuator element adapted to transmit vibrations thereto, said conical element engaging said diaphragm in an annulus around the diaphragm apex, the diameter of said annulus being materially less than the diameter of the diaphragm, and the said diaphragm and actuator element constituting the walls of a substantially closed air chamber thereb-etween. V r r 3. A loud speakerhaving a plurality of co-axially disposed interiitting conical diathe apex portions of which are connected together, the inner diaphragm being more sharply tapered than the diaphragm surrounding it whereby a radially outward expanding air chamber is provided between them, and actuating means for vibrating said and connected to the concave face of said inner diaphragm, and an actuating unit connected near the apex-of said actuating dia phragm and adapted to applyvibration to the latter.

5. A loud speaker according to claim 3, further characterized in that the said diaphragms are mounted 1n frontof a sounding:

board and spaced apart therefrom to permit the free egress of sound between said diaphragms and said board. r i

'6. A loud speaker according to claim 3,

further characterized in that the said dia-...

phragms are mounted in front of a soundi...

board with the basal portion of the outer or phragm approaching the said sounding be? 1 .1]:

but being separated therefrom to per free egress of sound between s 'd d' and an actuating i so ling board, and connected to smaller conical diaphragm lying larger diaphragm, whereby produced l y unit are tr diaphra through c smaller one.

7. A loud spealzer to claim further characterized in that at L ast one of said diaphragms is shaped to provide salient areas ezrtei ding materially beyond the central conical area, a sounding board spaced apart from the basal portion of the said diaphragms, an actuating unit mounted on said sounding board and an opposed conical actuating diaphragm fastened on the concave face of said inner diaphragm and adapted to transmit vibrations from said unit to said inner diaphragm.

8. Aloud speaker comprising a conical diaphragm, a substantially fiat sounding board, means to actuate said li phragm, said means being mounted directly a ainstsaid sounding board, the said conical diap ragm being disposed with its basal edge ad acent to but separated from the said s ding bears, the apex of said diaphragm being directed away trom said board.

9. A loud speaker according to claim 8, further characterized in that a second substantially flat sounding board is mounted to the rear of the said first-mentioned sounding board whereby to provide a sound chamber therebetween, said chamber permitting free egress of sound parallel to the plane of the sounding boards.

10. A loud speaker according to claim 8, further characterized in that spacing means are provided to hold the main area of the sounding board away from a wall surface against which it may be hung, whereby to permit free vibration of the board over the greater part of its area and free egress of sound from between the rear of the board and the wall against which it may be mounted.

11. A sound reproducer comprising a diaphragm having a central concave and substantially smooth portion and a plurality of salients projecting from said central portion, said salients forming continuations of the sloping surfaces of said central portions and providing diaphragm surfaces of substantial area which are more flexible than if they were included in the continuous central area of the diaphragm, and actuating means engaging said central portion to vibrate said diaphragm.

12. A sound reproducer according to claim 11, further characterized in that the said actuating means for vibrating said diaphragm is adapted also to provide the required diaphragm support, whereby the outer portions of the said diaphragm salients are permitted free and unobstructed movement.

13. A loud speaker comprising a vibrating diaphragm having a sbstantially smooth conical contour, the basal part of said conical diaphragm having a plurality of outer portions at a distance from the apex of the cone, the edge of the said conical diaphragm being formed so as to connect said portions by lines which approach the apex of the diaphragm at points between said outer portions, whereby the said outer portions are rendered relatively flexible as compared with the central portion of the diaphragm.

14. A loud speaker comprising a vibrating diaphragm having a substantially conical contour, the basal part of said conical diaphragm having a plurality of outer portions of substantial area, the edge of the cone being formed so as to connect said portions by lines which approach the apex of the cone at least as near as would straight lines connecting said outer portions, whereby the said outer portions are rendered relatively flexible as compared with the central portion of the diaphragm.

15. A loud speaker comprising a concave diaphragm,the surface of which slopes on all sides from an apex to a surrounding basal edge,the basal part of said diaphragm having relatively flexible outer portions of substantial area, the said basal edge being formed so as to connect said outer portions by marginal lines which have a maximum approach to the said apex at least as great as would straight lines connecting said outer portions, and means to centrally vibrate said diaphragm.

16. A loud speaker comprising a vibrating diaphragm, said diaphragm having a substantially smooth conical contour, the basal edge of said conical diaphragm having a plurality of symmetrically-arranged terminal points, said basal edge connecting said terminal points by lines which approach the apex of said conical diaphragm a suflicient dis tance at points intermediate said terminal points to provide the diaphragm with a plurality of salient portions of substantial area which are materially more flexible and easier to vibrate than if they mutually formed a part of a continuous conical surface.

In witness whereof, I have hereunto signed my name.

ANDREW F. WOO-D.

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