US1798157A - Sound-regulating device - Google Patents

Description

- 1931- c. D. HAIGIS v SOUND REGULATING' DEVICE Filed April 6, 1927 Patented Mar; 31, 1931 UNITED STATES PATENT oFFi'cE.

GABLETON n. rulers, or :EtADDONFIELD, NEW JERSEY, AssIGNoia TO vIc'roB 'rnixme menmn company, A CORPORATION or NEW EBsEY sounn-nneunnrme DEVICE Application filed April 6, 1927. Serial No. 181,483.

This invention relatesto sound producing and reproducing instruments, and more particularly to instruments of the character employing a vibratory element of conical or frusto-conical formation.

It is an object of this invention to provide I a sound producing or reproducing instrument employing a conical or frusto-conical Vibratory element with means whereby the quality of sound radiated therefrom is improved.

' Another object of this invention is to provide a vibratory element of conical or frustoconical formation with means for minimiza ing or eliminating interference arising from the radiation of air waves which are out of phase from different portions of said vibrator element. I (gther objects will appear as the description of the invention proceeds.

The invention is capable of receiving a variety of mechanical expressions, one. of which has been shown on the accompanying drawing, but it is to be expressly understood that the drawing is for purposes of illustration only and is not to be construed asa definition of the limits of the invention, refer- ;ence being had to the appended claims for that purpose.

Referring in detail to the drawing wherein the same reference characters are employed to designate corresponding parts in both figures,

Fig. 1 is an elevation, partly in axial section, of an embodiment of the present invention, and I Fig. 2 is a face view.

-In the form sho"wn, the sound producing or reproducing instrument takes the form of an electro-magnetic receiver of the character commonly employed in loud speakers, but

it is to be expressly understood that the actuating mechanism for the vibratory element to be described may be of any suitable char} acter and construction. and while the invention has particular utility in connection with loud speakers and electro-magnetic receivers, the invention within its broader aspects is applicable to mechanically as well as electro- 30 magnetically actuated vibratory elements.

As shown, the casing 1 of the instrument is mounted in any suitable way, as by a bracket 2, on any suitablesupport 3. Within the cas-. ing 1 are shown more or less diagrammatically the conventional elements of an electro-magnetic receiver including the core 4 and coil 5 provided with leads 6. Supported from the face of the casing 1 in any suitable way, as by a housing ring or bracket 7, is a vibratory element or diaphragm 8 .of any suitable size, construction and material and of conical or frusto-conical formation. The diaphragm is attached to a flexible peripheral ring 9 which is clamped at its margin between the flange 10 of the ring 7 and the clamping ring 11, one or more gaskets such as shown at 12 being interposed if desired. The smaller or inner end of the diaphragm 8 carries a flexible spider 13 which is attached in any suitable way, as by a screw 14, to the core 4, and it also carries, or is suitably connected with, the armature,-movable coil or other means bv which vibrations are imparted to the diaphragm. The apparatus so far describedis shown as mounted with its diaphragm 8 op; posite an aperture 16in a wall or partition 17 with aring18 interposed between said wall and the clamping ring 11. Further description of this apparatus is deemed tobe unnecessary as'the details thereof form no part ofthe-present invention, and maybe of any conventional or suitable construction. In conformity with the present invention, a conical or frusto-conical member 20 of any suitable material, such as wood, is mounted, preferably rigidly, within the cavity provided by the diaphragm 8. As shown, said member 20 is mounted by one or more brackets 21 suitably secured at one extremity to the partition 17, as by screws 22, and suitably secured at the opposite extremity to the member 20, as by screws 22". While within the broader aspects of this invention said member 20 may be made solid, it is preferred to cutout the central portion of said memher, as shown at 23, but leaving an, annular surface 24 at the base of the member which formed may be parallel to the outer wall, or it may be tapered toward the inner end as illustrated.

The outer'wall of the member 20 is preferably substantially parallel with the inner surface of the diaphragm 8 and as a general rule, said member will be conical or frustoconical as the diaphragm is conical or frustoconical, said member being made of such size as to be spaced from the diaphragm 8, by a narrow but substantial distance, substantially throughout the extent of the inner conical or frusto-conical surface of said diaphragm. Said member 20 should not be so near the diaphragm as to effect a dampening action thereon, nor should it be so far from the diaphragm as to permit converging out-of-phase vibrations to be radiated directly from different portions of the diaphragm. While there may be some variation in the width of the annular air channel thus formed between the member 20 and the diaphragm 8, a spacing on the order of a quarter of an inch has been found to produce good results.

The exact cause of the improved results obtained by the use of the present invention may not be fully understood, but is believed to be as follows:

For wave lengths greater than the length of the generatrix of the cone or conic frustum forming the diaphragm 8 as shown, said diaphragm apparently acts substantially as a piston. For that wave length which is equal to the length of said generatrix, and for partials thereof, said diaphragm apparently acts also as a diaphragm and only partially as a piston, and has vibratory movement substantially at right angles to its surface. When said diaphragm is producing or reproducing a wave length which is equal to the length of said generatrix, for example, a wave motion is. set up in the diaphragm, and the motion at any point in said diaphragm is 180 out of phase with the motion of said diaphragm at another point spaced axially along said diaphragm by a distance equal to a half wave length. If the vibrations imparted to the air at these two points pass directly out into space in straight lines, there is destructive interference. Similarly the same is true of all other points on the diaphragm having the relation specified. Likewise an analysis of what occurs when the wave length is a partial of that wave length which is equal to the length of said generatrix shows that interference arises whenever the diaphragm is vibrated to generate any sound wave which is equal to said generatrix or any partial thereof.

The present invention prevents direct radiation into space of any sound waves set up by suchtransverse vibratory movements of the diaphragm, because the air waves generated by the transverse vibrations of the diaphragm are caused to move substantially parallel to the surface of the diaphragm. The possibility of interference is therefore minimized or prevented, because while a polnt on the diaphragm may still be 180 out of phase with another .point one-half wave length removed therefrom axially along. the diaphragm, by the time the vibratory impulse imparted to the air at the first point has moved through half a wave length along the diaphragm, the second point has moved through one-half of its cycle of oscillatory motion and is now in phase with the air wave reaching that point.

As the exterior surface of the member 20 is spaced from the diaphragm 8 sufiiciently to prevent all dampening action, said member acts to enforce movement of the sound waves parallelly to the surface of the diaphragm or vibratory element and prevents interference by causing vibratory impulses to be in phase by reason of the travel of the sound waves parallelly to the surface of the vibratory element.

Whether or not the foregoing explanation is technically correct in all respects as to the cause of the improved results obtained,

investigation has demonstrated that the present invention is productive of substantially better sound production and reproduction than has heretofore been obtained with frusto-conical or conical diaphragms.

While the embodiment of the invention illustrated on the drawing has been described with considerable particularity, itis to be expressly understood that the invention is not to be restricted thereto, as the same is capable of receiving a variety of mechanical expressions, some of which will now readily suggest themselves to those skilled in the art while changes may be made in the details of construction, arrangement and proportion of parts without departing from the spirit.

of this invention. Reference is therefore to be had to the appended claims for a definition of said invention.

What is claimed is:

1. In a sound producing or reproducing free bodily piston-like movement in the direction of the conical axis, means having a direct mechanical connection with said diaphragm and operable through such connection to impart such movement to said diaphragm, and a hollow member open at both ends thereof and 'havin substantially the same configuration exterlorly as the configuration of said diaphragm, said member supported independently of and in spaced relation with respect to said diaphragm with its axis substantially coincident with that of said diaphragm, the apex portion of said member disposed adjacent such portion of said diaphragm.

3. Ina loudspeaker, a diaphragm of substantially conical configuration supported for free bodily piston-like movement in the direction of the conical axis, means having a direct mechanical connection with said diaphragm and operable through such connection to impart such movement to said diaphragm, and a hollow member open at both ends thereof and having substantially the same configuration exteriorly as the configuration of said diaphragm, said member disposed with its axis substantially coincident with that of said diaphragm and supported at its larger end in spaced relation to and independently of said diaphragm, the apex portion of said member disposed adjacent such portion of said diaphragm.

In testimony whereof I have signed this specification.

CARLETON D. HAIGIS.

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