US1877294A - Loud speaking reproducer - Google Patents

Description

Sept. 13, 1932. GEORGE I 1,877,294

v LOUD SPEAKING REPRODUCER Filed Dec. 10, 1928 5 Sheets-Sheet 1 F lgri I 1Q-f] 3mm R055 F George Sept. 13, 1932. R. F. GEORGE 1,377,294

LOUD SPEAKING REPRODUCER Filed Dec. 10, .1928 5 Sheets-Sheet 3 smut R05; FGeorg P 13, 1932- R. F. GEORGE LOUD SPEAKING REPRODUCER Filed'Dec. 10. 1928 5 Sheets-Sheet 4.

- 3mm Ross F George 16 5 dumm Sept. 13, 1932. R. F. GEORGE 1,877,294

LOUD SPEAKING REPRODUC ER Filed'Dec. 10, 1928 5 Sheets-Sheet s Q TT Patented Sept. 13, 1932 UNITED STATES ROSS F. GEORGE, OF SEATTLE, WASHINGTON LOUD SPEAKING REPRODUCER Application filed December 10, 1928. Serial No. 324,826.

My invention relates to loud speakers, and

is particularly adapted to cone speakers, although not necessarily limited to the use of cones as tympani.

My invention is particularly concerned with the manner of supporting the tympanum or tympani, and'with the employment of a vibratory supporting member by means of which the cone or other tympanum is prevented from rattling, yet which supporting member will pick up the vibrations which would otherwise be lost or absorbed, transmitting theminto sounds which are amplified and blended with theheavier tones picked up by the cone, blending the two types of tones together, th one t complement the other, and thus to reproduce more nearly the natural relationship or balance of the tones. The supporting member functions as an amplifying member for the lighter tones, and in some degree for the heavier tones. Thus my invention has for its principal object the association of a tympanum with a supporting member to obtain clarification and amplification of the various vibrations, and to bring moreofthe finer vibrations into audible tones for the reproduction of harmonius shadings.

More specifically my invention has for its object the assemblage of a tympanum, as a vibratory cone, directly upon a sheet of flexible material such as cloth, paper, screen, or the like, the sheet or supporting member being in part foraminous to permit passage of sound therethrough, and in the case where two or more cones are employed affording a rattle-proof means of securingthe cones in their proper position on'the supporting membrane to form a resonance chamber for the ripening of tones which are ermitted topass through the open mesh or her of the sheet, which also picks up the finer tones and carries them ofi' into selected portions of the sheet for amplification and blending with the other tones.

It is another object so to support two or more'cones upon a stretched membrane that the sound selected-and defined by the inherent characteristics oft-he cones may be projected from the space between them, the extension of the membrane outwardly serving as a resonance pick-up means for the otherwise lost vibrations from the cone, and as a means of conveying,vand, to some extent, amplifying these tones issuing from the cone or cones. I

A further object is the provision, in association with the sound producing tympanum, of a condition, approaching the arrangement of the nasal and vocal passages in the human head, wherebyto produce a resonance chamber in association with one part of the tympanum, while permitting free projection of sound from another portion.

A still further object is the connection of an actuating member, such as the reed or armature of the electro-magnetic unit usually employed with loud speakers, to a tympanum supported upon a sheet or membrane which has both transverse and longitudinal resilience, in such away as to transmit to the tympanum, and thence to the membrane, a pushand-pull force and a longitudinal or lateral force, thus to provide-a more natural driving impulse for the tympanum or tympani, and to utilize to the fullest the force of theactuating member and the capabilities of such a membrane.

Otherobjects will be ascertained from a study of the specification, drawings, and claims.

Myinvention comprises the novel parts and the novel combination and arrangement thereof, as shown in theaccompanying drawings, described in the specification, and as particularly defined by the claims terminating the same.

In the accompanying drawings I have shown by invention in a number of forms, largely diagrammatically illustrating the principles of my invention.

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Figures 1, 2, 3, and 4 are diagrammatic views in axial section illustrating various embodiments of my invention employing a cone as the primary tympanum.

Figure 5-is a face view of the membrane employed with certain of these embodiments, and other illustrated in later views.

Figures 6, 7, 8, and 9 are like diagrams, illustrating the principles of the invention employed in arrangements of multiple tympam.

Figure 10 is a similar axial section through a form similar to Figure 9, showing a mounting in association with a cabinet and resonance chamber therein, approaching the arrangementot the human resonance chamber.

Figures 11, 12, 13, 1 1, 15, 16, and 17 are similar diagrammatic sectional views of modified embodiments of my invention, both multiple and single tympani being illustrated.

Figures 18 and 19 are like axial diagrams illustrating the manner of obtaining an ob-.

lique combined push-and-pull and rolling movement of the membrane and tympanum, such as is particularly capable of accomplishment with a membrane of the character which I will describe.

Figure 20 is a modification which reproduces after the fashion of the human throat and mouth.

Figure 21 is an axial diagram showing two independently actuated sound sources arranged tohave the sounds amplified by a common membrane.

Figure 22 is an axial diagram of two independent connections from a single impulse source or a membrane, each delivering aspecial type of impulse.

Figure 23 is a face view of a membrane,

to which a cone is attached, illustrating a manner of filling in the foraminous center of the cloth membrane,

Figures 24, 25, and 26 are axial diagrams illustrating the mounting of a membrane upon I have found through experiment and trial that any given tympanum, whether of cone shape or otherwise, and actuated by some ac tuating member under the influence of a sound impulse, will select and respond most strong ly to certain ranges of pitch which are within its capabilities. Ranges outside of the capability of the selected tympanum are largely lost, and it is at present the practice to deaden the edge of the tympanum and to absorb and lose the tones which cannot be reproduced by the tympanum, so as to avoid an objectionable rattling of the edges of the tympanum. I propose to support the tympanum directly upon a sensitive and vibratory membrane, to which these tones may be transmitted from the tympanum, or to which they may be communicated direct, so that they may be reproduced by this membrane, clarified. and amplified t give them the value with relation to the tones produced by the tympanum which they have in the original rendition of the selection, and thus to round out and ripen or fill out the composite tones reproduced, and to render them more natural.

\Vhen two or more tympani are placed in juxtaposition or opposed to one another they will form a sound or resonance chamber between them, in which the several inherent pitches are blended, and from which they issue as a composite blend of the several tones. I have found that the production or definition of tones in tympani is lar ely at the periphery of the tympani, and that if these tympani are unsupported at their peripheries there are produced stray or wolf tones which are undesirable. As has been noted above, these stray tones can be largely absorbed, but this makes the tone hollow or lacking in those finer tones which go to make up the whole in the original rendition, and especially is this noticeable where two or more tympani are employed together, of different inherent resonances, and therefore selecting and amplifying most strongly certain tones, but leaving out the others.

Accordingly, by my invention, the supporting membrane picks up these stray tones, and by its own vibration reproduces and am plifies them, and blends them with the stronger tones produced by the tympanum or tympani attached to the membrane, or in juxtoposition thereto. The several figures illustrate various forms of applying my invention in practical operation. Figure 1 illustrates perhaps the simplest form of a tympanum 1, actuated from suitable source 6 of sound impulses by a more or less rigid stem 2, the edge of the cone 1 being secured to a membrane 3, which may be of cloth, paper, screen material, or any suitable vibratory material. As illustrated, the center of the cone is left clear, without any of the membrane 3 extending thereacross, and the membrane 3, if made of woven cloth, for example, may have its interstices filled, as by painting the cloth so that it will serve as a complete vibratory, unitary diaphragm or membrane. It is, of course, held in some suitable manner about its edges, and is preferably under some tension, so that it is more or less tightly stretched. The finer tones passing from the edge of the cone 1 are taken up by the membrane 3, and by the membrane reproduced, rather than smothered or absorbed, and blended with the tones from the cone 1.

In Figure 2 the construction is uite similar to Figure 1, except that the mem rane 3 is extended across the mouth of the cone, as indicated at 30, and the painted portion is extended inwardly of the edge of the cone. as is indicated by the heavy line at 31. This peripheral portion 31, extending inwardly of the mouth of the cone, acts in a sense as a. baffle, and forms within the cone a resonance 4t employed to restrain this free edge.

chamber, giving-the tones issuing from-it a greater fullness.

In Figure 3 the stem 2 is in effect extended through the cone 1 to a point of engagement with the membrane which is stretched across the cone, a string 2 serving as the extension of the stem, and the central portion of this membrane has its interstices filled, as is indicated at 32. This portion 32, then, acts as a second tympanum. However, there would be little amplification of the tones picked up by this portion 32, were it not for the fact that means are provided for communicating its vibrations to the larger portion of the membrane 3 outside of the cone 1. Thus, as may be seen in Figure 5, rays or paths 33 are provided for communication between the central closed area 32 and the outer main portion of the membrane 3. Largely, however, the membrane between the central portion 32 and the edge of the cone 1 is left with its interstices unfilled, as is indicated at 34. Figure 1 is like the form shown in Figure 3, except that the central portion 32 is not tensioned in Figure 4, as it is illustrated in Figure 3, and in Figure 4 the large diaphragm 1 is not secured directly to the membrane 3, but has its edge free, and there is provided an absorbing connection 4, as chamois or felt, for example, to make a dampening connection between this cone 1 and the membrane 3. Thus the finer tones are communicated to the membrane 3, not through the tympanum 1, but more direct- 1y from the stem 2 to the central portion 32, and thence by way of the rays 33 to the main portion of the membrane 3. I

In Figure 6 a second, smaller cone 10 may be employed, in addition to the main cone 1. In this view I have shown the membrane 3 at the point of connection to the smaller cone 10 as having its interstices filled, as is best in-' dicated at 36, and this portion would communicate with the portion outside of the cone 1 by rays similar to 33, as seen in Figure 5.

In Figure 7 the membrane 3 is stretched over a frame 5, and vibrations are communicated thereto from the smaller cone 10, rather than from the two cones, and the cone 1 is left with its edge free, with the dampening strip In Figure 8 two minor cones 10 and 10 are employed, being connected by subsidiary stems 20 to the main stem 2. All the cones 10, 10, and 1 are shown in this form as connected to the membrane 3.

In Figure 9 the cones 1 and 10 are shown as opposed one to the other, to form between them a resonance chamber. In this instance only one of the cones, that is, the cone 1, is shown as transmitting vibrations to the membrane 3, though the cone 10 may also be secured thereto, but by reason of the fact that the interstices are not filled in the central portion of the membrane, that to which the cone 10 is secured, this central portion is not audibly vibratory, but acts only as an absorbing medium. The effect of the cone 10 is, in association with the cone 1, to form a resonance chamber, from which the tones issue through the annular space between the edges of the two cones. In this form the electromagnetic unit is illustrated at 6, and the device is shown as enclosed within a cabinet 50, having an open front or grille work 51.

Figure 10 illustrates a construction quite similar to Figure 9, except for the fact that the frame 5, to which the diaphragm is secured, extends below the bottom 52, defining the resonancechamber 53 within the cabinet 50. In other words, sound issuing from the resonance chamber between the cones 10 and 1 is emitted partly within the chamber 53, and thence through the grille 51, and is partly given out to the open air. Thus, the chamber 53 serves in the same manner as the throat and nasal passages of the human head.

In Figure 11 the smaller cone 10 is left entirely free, and a resonance chamber is formed between this cone and the main cone 1, which is secured at its edges to the membrane 3.

In Figures 12 and 13 a single cone 1 is shown as connected to, and as extending or stretching the diaphragm 3. This tendency to pull the diaphragm to one side is resisted, in the one case by two springs and 56, the one at the top and the one at the bottom of the frame 5, and in the other case by securing the lower edge of the frame 5 to the casing 50, but employing the upper spring 55 to permit oscillation or rocking of the frame. These arrangements are peculiarly adapted to a special drive arrangement which will be described later.

In Figures 14, 15, and 16 two membranes 3 and 35 are employed, both preferably connected to the same frame 5, and the cones 1 and 10 are secured to the respective membranes 3 and 35. In Figure 14 the stem 2 is shown as extending, not directly to either of the cones 1 or 10, but by means of the bell crank levers 21 and 22, to the auxiliary stems 23 and 24, connected to the respective cones 1 and 10. In the lever 21 the arrangement of the long and short arms is such that the cone 1 has its amplitude increased with respect to the vibration of the armature of the electromagnetic unit 6, and the arrangement of the long and short arms of the lever 22 is such that the cone 10 has its amplitude decreased with respect to the amplitude of the armature 60. The effect of this, of course, is to strengthen such tones as are inherently reproduced by the cone 1, and to weaken those which are picked up best by the cone 10. It will be noted that the membranes 3 and are not completely filled in, but may form a type ofgrille work, so that they vibrate largely .as a unit, yet permit the I ployed, both connected to the armature 60,

but at different distances from its fulcrum 61. In this manner the cone 1 1S given somewhat greater amplitude than the cone 10. However, both cones are shown as secured to the same membrane 3.

In Figure 20 the membrane 3 is stretched over aframe 5, and has its interstices largely filled, except at 30, in front of the lower portion of the cone 1. Thus a local resonance chamber is former. between the cone 1 and the membrane 3. The cone in this instance is well towards the lower edge of the membrane, and the entire upper part thereof acts to amplify and reproduce the lighter tones.

A membrane such as asheet of cloth painted, or otherwise made to act as a unitary membrane, will reproduce certain tones by a push and pull impulse, while other tones will be produced and strengthened by a lateral movement, or movement ithe general plane of the membrane. If, therefore, means are provided for imparting both types of impulses to such a membrane, the result will be more complete utilization of the impulses and a better tone. Accordingly, as shown in Figures 18 and 19, such a result may be produced by the application of the impulse to a membrane 3 in a manner which I will tie scribe.

If the vibrating armature of an electromagnetic unit be set to vibrate in a plane which is oblique to the plane of the membrane 3, and be connected to the membrane or to a cone or like tympanum 1 by a stem 2 which lies normal to the plane of the membrane 3, or in the axis of the cone 1,.vibration of the armature 60 will cause, not only a to and fro or push-and-pull movement of the membrane, but in addition, and by reason of the stretching of the membrane, will cause a rolling movement, or movement in the general plane of the membrane. I have attempted to illustrate this in Figure 18, the solid line representing the normal or neutral position of the cone 1, the membrane 3, and the stem 2. Movement of the armature G") in one direction will cause movement of these elements in the direction indicated by the small dots, and will cause a tension on the upper portion of the membrane 3, and slackening of tension in its lower portion, while this is immediately followed by movement of the armature in the opposite direction, causing a slackening of tension in the upper part of the membrane 3, and an increase in tension Lmmammmmmmmt in its lower portion, as is indicated by the dash line position of the figure. This, then, produces a combined push-and-pull and lateral movement of the membrane.

This same effect may be produced by connecting a stem 25, vibratedin the ordinary manner by the armature 60, to a T-shaped member 29, supported to fulcrum at 26, the stem 25 being secured to one arm and the stem 2 to the cone 1, being connected to the other arm of 29. As the arm 25 is reciprocated, the member 29 rocks on its fulcrum 26, and this gives to the stem 2 a rolling motion, and the cone 1 and the membrane 3 are given a combined push-and-pull and lateral movement, or a combination movement which is described above. This effect is peculiarly capable of accomplishment with a diaphragm of the general type described, and actuated through a stiff tympanum or member such as 1, which fixes and transmits the oscillations to the membrane.

A similar result may be achieved by the arrangement of Figure 22, wherein the stem 25, which is directly connected to the armature 60, is connected to a flexible bowed member 29, which is secured at its ends, and which consequently tends to bow more, and to flatten out. This gives the peculiar rotary oscillation to the cone 1 and membrane 3, through the stem 2, and the more pronounced lateral movement may be additionally transmitted to the membrane by an oblique stem 27. Figure 23 illustrates how the face of such a membrane may appear, with the inner filled portion closely surrounding the periphery of the cone 1, and broadened at top and bottom to obtain the baflling effect of human lips. This portion 32 is largely cut off from the main filled portion of the membrane, except by narrow rays 33, so that the vibration of the main portion is chiefly the result of vibration of the stem 27. I have shown this main filled portion as surrounded by an unfilled peripheral ring 37, by means of which the ultimate vibrations are absorbed, and are not transmitted to the supporting frame or cabinet.

In Figure 21 two sources 6 and 6 of sound impulses are connected to two cones 1 and 1, both of which are secured to a common membrane 3.

In Figures 24, 25, and 26, instead of supporting the cones on membranes, the vibrations of the cones may be transmitted to membranes supported in or on the cones, and a second cone may be supported on such a membrane, as may be seen in Figure 24.

I may point out here that my invention offers a. solution to the difliculty generally experienced in mounting a cone or like tympanum so that it is free to vibrate, yet does not produce a rattle at its edges. If the cone be secured about its edges to a membrane, either foraminous or non-foraminous, it may still A no vibrate within the limits of its actuating force and of the membrane. If the membrane be resonant, it will pick up and amplify the vibrations transmitted from the cone, as has been explained above. If the membrane be non-resonant, it will still pick up the vibrations, and they will be absorbed, but in either event they will be carried away from the edge of the more or less rigid cone, and its tendency to rattle will be eliminated. As a practical form of such an arrangement, a cone or cones may be mounted upon a membrane or membranes of cloth, just as shown in the various figures of the drawings, and these cloth membranes will not have their interstices filled with paint or otherwise, but will remain foraminous, at least, in the vicinity of the edge of the cone, to permit projection of sound.

h at I claim as my invention is:

1. In a loud speaker, in combination, a membrane tensioned to a point where it has resonance, a tympanum associated therewith to transmit sound impulses thereto, and actuating means operatively connected to said tympanum.

2'. In a loud speaker, in combination, a membrane tensioned to a point where it has resonance, a tympanum connected to vibrate the membrane, and means for vibrating said tympanum in accordance with sound impulses, and thereby audibly exciting said membrane.

3. In a loud speaker, in combination, a flexible membrane capable of resonance, a tympanum secured thereto, a source of sound impulses, and means for setting said tympanum and membrane into audible vibration, in accord ance with sound impulses from said source.

4. In a loud speaker, in combination, a flexible membrane capable of resonance, a tympanum secured thereto, a source of sound impulses, and means operatively associated with said sound source on the one hand, and said tympanum and membrane on the other hand, to impart to the latter a vibratory movement compounded of movement in its own general plane, and likewise transversely thereof.

5. In a loud speaker, in combination, a flexible membrane capable of resonance, a tympanum associated therewith to impart sound impulses thereto, a source of sound impulses including a member vibratory in the same plane and in a plane oblique to the general plane of the membrane, and means connecting said vibratory member to the tympanum.

6. In a loud speaker, in combination, a membrane of cloth, a tympanum secured thereto, said membrane being stretched outwardly of the tympanum, and the interstices of the cloth being filled, in areas including the edge of the tympanum, to vibrate as a resonant unit, and a source of sound impulses operatively connected to said tympanum.

7. In a loud speaker, in combination, a cone,.a membrane of cloth stretched over the base of said cone and extending therebeyond, the interstices of the cloth being filled, in areas extendingoutwardof but including the periphery of the cone, to vibrate as'a resonant unit, and a source of sound impulses operativelyconnected to said cone.

8. In a loud speaker, at least two sound reproducing members of' different inherent pitches, a source of audio-frequency impulses, and meansconnecting' each of said members to the common impulse source, said members being so disposed relative to each other as to modify and blend with the sound from the one the sound from the other.

9. In a loud speaker, a plurality of sound reproducing members of inherently different pitch characteristics, a common actuating source of audio-frequency impulses, and a common means connecting each of said members to the actuating source to be actuated thereby, said members being disposed and arranged relative to each other to form a plurality of communicating resonant chambers.

10. In a loud speaker, a plurality of independently supported sound reproducing members each having a characteristic resonance differing from that of any other member of the series, an actuating source of sound impulses of varying frequencies, and means mechanically connecting each of said members to the common source, whereby each will respond to its characteristic resonant frequency, said members being disposed, relatively to each other, to form a resonance chamber wherein the sounds of different pitch may be reflected from other members and blend with the characteristic sounds of the latter, prior to issuance from such resonance chamber.

11. In a loud speaker, at least two cones of different inherent resonances, each having a dished conformation facing a like dished conformation of the other, to form a resonance chamber, and spaced at their peripheries to provide an outlet from such chamber, an actuating source responsive to impulses of a Wider range of frequencies than any one of said cones, and embracing the characteristic frequencies of all, and a common means operatively connecting each of said cones with said source.

12. A loud speaker including two cones of different diameters, disposed one facing, but not touching the other to form a resonance chamber therebetween, an actuating source and a rod extending therefrom and responsive thereto, said cones being connected to said rod.

13. In a loud speaker, a plurality of cones of different inherent resonances designed, disposed and arranged to reflect sound from one to another, and to blend such sounds, and a common actuating means for the several cones.

14:. A loud speaker including a plurality b of cones disposed with hollow portions of one towards hollow portions of another, to form resonance chambers therebetween, and each of said cones being of differing resonant characteristics, a common actuating member In to which all of said cones are connected, and I a single impulse source for said actuating member. Signed at Seattle, Washington, this 3rd day of December, 1928. 15 ROSS F. GEORGE.

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