US1985881A - Sound apparatus - Google Patents

Description

L.. J. BUCKLE! SOUND APPARATUS Jan. 1, 1935'.

Filed Aug. 27. 1934 2 Sheets-Sheet l INVENTOR. L 0 Bue/(LEY.

Y E N R O T A Jan. 1, 1935. J. BUCKLEY 1,985,881

SOUND APPARATUS Filed Aug. 27, 1934 2 sheets-sheet 2 INVENTOR. so J. BUCK/.Ex

Patented Jan. 1, 1935 UNITED STATES PATENT OFF-ICE Claims.

My invention relates to sound apparatus and has for its primary object the provision of a sound box in whch a loud speaker such as is commonly used in radio receiving sets and the like, is mounted and which is so designed as to produce the audible translation of the sound waves emanating from the loud speaker diaphragm over a maximum frequency range and in natural character and tone.

It is known that when a loud speaker unit including the diaphragm which translates the electrical impulses into audible sound waves, is mounted Within a box or container, the faithful translation of the sound waves of Various fre quencies and particularly those of the low frequency type is effected by the character of the box and the chamber therein within which the loud speaker is mounted. This is due to the fact that the diaphragm, usually of substantially cone shape, during vibration, sets up the vsoundwaves on both sides of the diaphragm. There is, of course, customarily provided an opening in the front wall or panel of the V box directly behind which the loud speaker diaphragm is mounted so that the sound waves emanating from the interior surface of the diaphragm pass directly to thev atmosphere outside of the box. Ordinarily, however, the chamber in the box within which the loud speaker isv mounted has been more or less closed to the atmosphere except for such opening, with the result that the vibrations or sound waves emanating from the outside surface of the diaphragm meet with an air pressure comprising the air bottled up in the chamber and surrounding the diaphragm.

I have discovered that while a certain amount of this air pressure or air resistance within the chamber to the sound waves is essential for the audible translation of certain of the sound waves, particularly those of the low frequency, I have also discovered that the amount of such air pressure depends upon several factors among which are the size of the chamber, the energy of the loud speaker unit, and the amount of free air communication between the rear surface of the diaphragm andthe atmosphere.

I am awarethat others have recognized these conditions in part and have attempted to provide the required balance between the air pressure within the chamber and the atmosphere by providing channels of communication therebetween. In such attempts, however various other elements and means have been introduced which tend to render more diicult the delicate balance required between the chamber and the atmosphere.

By my invention I have provided a very simple and economic structure by which the balance between the air within the chamber and the atmosphere can be easily obtained and regulated without the addition of extraneous elements such as hoods, tubes, interior casings, etc., and which by virtue of its simplicity and direct control makes possible a true translation of the vibrations of the diaphragm into audible sound Waves.

One of the principal objects of my invention lies in the provision of an opening in the front board or panel of the box which is of such size with respect to the diameter of the diaphragm of the loud speaker and the air capacity of the box itself that for a loud speaker of given energy the proper balance is obtained between the interior of the box and the atmosphere thus providing for a true' rendition of the original soundras translated by the loud speaker unit.

Another object of my invention is to provide a meansrcooperating with the diaphragm in the chamber for affecting the amplitude of sound vibrations of certain vfrequencies without disturbing or affecting the other sound frequency Waves emanating from the diaphragm.

Other objects and advantages in details of construction will beapparent as the description proceeds, reference now being -had -to the figures of the accompanying drawings forming a part of this application and 'wherein'like reference numerals indicate like parts.

In the drawings:

Figure 1 is a front View of a sound box embodying my invention.

Figure 2 is a sectional view thereof taken on the line 2--2 of Figure 1.

Figure 3 is a detail sectional View taken on the line 3-3 of Figure 2.

Figure 4 is a front View of a slightly modified form of sound box embodying my invention.

Figure 5 is a sectional view taken on the line 5-5 of Figure 4.

Figure 6 is a front view of a still further modied form of sound box embodying my invention.

Figure 7 is a sectional view taken on the line 7-7 of Figure 6.

Figure 8 is a perspective view of the attachment used in connection with my invention.

Figure 9 is a front view of a further modified form of sound box embodying my invention.

Figure 10 is a sectional View thereof taken on the line 10-10 of Figure 9.

This application is a continuation in part of my application Serial No. 671,670 filed May 18, 1933.

The reference character 1 refers generally to a sound box, the front wall 2 of which is provided with an opening 3 hereinafter referred to in more detail. Within the chamber 4, closed to the atmosphere except for the opening 3, there is suitably mounted as by means of a bracket 5 a loud speaker unit 6 of any desire type or construction. This loud speaker unit is provided with the diaphragm 7 of the usual substantially cone shape which projects forwardly toi a pointin .registry with the o Y ening 3 in the front board or panel 2.

Adjacent the rear side of the box there may be provided guides 8 by means of which removable partition boards 9 and l() may be inserted across the rear of the box whereby to selectively change and reduce the Volume of the box between .the front board and the back, that is,` reducel the size of the air chamber within which the loud speaker is mounted. This may be desirable withr certain sizes and types of loud speakers and provides a means of roughfvadiustment to bring the volume of the sound chamber to the desired amount.

The diaphragm'v 'Z is usually provided with a fastening rim l1 adjacent its front end and as a means of support this ring is connected at spaced points by means of the ears or lugs A12 to the front board 2 of the box.;` The sizeof these lugs 12 is such as not to interfere, materially withthe communication between the chamber 4` and the atmosphere. l A

Thesize of the opening?, is extremely important depending, as beforeI stated, upon the energy of the speaker and more particularly upon `the volume of the chamber within which the speaker is mounted. It is also important that there be no intermediate elements betweexifthe rear surface of the diaphragm l andl thesopening 3, L Thisl is clearly illustrated'in Figure 2I where itwill be observed that free and directcommunication exists between the Y, chamber- 4 immediately surrounding thev diaphragmand the atmosphere,

an opening 14 inches in diameter, leaving a l inch passage around the outer edge of the diaphragm and its frame, allowing a direct passage between the chamber directly` adjacent the outer surface of the diaphragm and the atmosphere, When the baie attachment, hereinafter described, is used, avery faithful reproduction is obtained having a measured frequency responseof from 35 cycles per second to-16,500 cycles pervsecond.

In the operation of thejinvention the vibration of the diaphragm 7 and particularly the Vibrations of the outer surface thereof, set up corresponding air waveswithin the. chamber 4 and with the proper balancebetween the. air in the chamber and theatmosphere through the vopening 3, the-widest; possiblerange of frequencies will be rendered audiblebecause of the proper inuence of the air pressure within the chamber uponthe emanating sound waves. Thus. by providing the proper sized opening 3 and the elimination of intermediate elements between the diaphragm and opening, I am able to provide the proper balance between the chamber and atmosphere which results in the true rendition of the vibrations of the diaphragm as sound waves and over a greater range of frequency than heretofore possible.

In Figure 4 there is shown a slightly modified form of the invention in which the front board 2a of the box la is provided with the opening 3a. In this form the diaphragm '7a projects through the opening 3a a slight distance bringing the attaching rim 11a and fastening lugs 12a outside of the box.

In Figures 6 and "I, a still further modification is shown in which the front board 2b is comprised of preferably porous material such as burlap 13 between the layers of which is loosely provided sound absorbing material 14 of any desired character. 'Ihe opening 3b is dened by a ring l5 and to. which the rim 11b of the diaphragm is secured as by the` lugs 12b. In this modification the front edge of the diaphragm 7b .is mounted so as to be flush with the front wall of the front board 2b and as in the other cases, the opening 3b in the front board is of a diameter larger than the diameter of the diaphragm 7l; and its rim 1lb whereby to permit free and direct access to the atmosphere from the chamber 4b.

In Figures 9 and 10 I have shown a further 1" modification in which the box 1c is entirely open at the lfront as at 3c omitting the front board entirely. In this form there is provided the maximum freedom of passagefor the sound waves emanating from the rea-r of the diaphragm 'To tothe atmosphere, it being understood, of course, that the size of the opening 3c is in proper proportion to the size: of the diaphragm and the volume of the box chamber as previously explained. In this form,V the narrow strip 5c extending from top to. bottom of the box supports the loud. speaker unit (5c. Ifdesired for decorative purposes, a very thin and extremely porous screen 32d4 maybe provided over the open front 3c but care should be taken to use. a material which will not appreciably affect the-freeand unrestricted passage of. the sound waves from the box to theatmosphere.

It` is .considered a decided advantage to providethis opening orbcommunication between at-` mosphere andchamber at a point directly adj acentr the front peripheral edge of the diaphragm. This is probably due to the fact that the vibration of the diaphragm next totheA front edge thereof corresponding to certain low frequencies are very weak and without the direct communication to the atmospherel at this point, coupled with the balancingV feature between atmosphere and chamber pressure at this same point, such frequency would be lost to audibility.

With reference to.y Figuresy 2 and 8 it will be noted that I havev provided an attachment which may be used with, facility to increase the amplitude of certain of the sound waves emanating from the back surface of the diaphragm. This attachment comprises the baies 16; surrounding the diaphragm but spaced apart as shown soA astopermit free air communication between the diaphragm and the chamber around thek edges of the bafiies. These baies may be held togetherv in this spaced relation by thek pins 1'7 and the entire unit supported in position by the bracket 18.

It will be noted that the baiile unit is positioned short vof the front. endY of the diaphragm. This is to leave this front portion of the diaphragm, from which the low frequency sound waves largely emanate, uninfluenced by the bailies. The bales, therefore, act upon the middle register frequencies only and tend to amplify them, a desirable function for proper balance of sound translation.

It Will be clear too, that the use of this bafiie device does not materially aifect the free air communication between the diaphragm and the opening 3 to the atmosphere.

Of course, changes may be made in details of construction and arrangement of parts Without departing from the spirit and scope of my invention. I do not limit myself, therefore, to the exact form herein described other than by the appended claims.

I claim:

1. A sound apparatus comprising a chamber of determined volume, and a sound unit in said chamber including a vibratile diaphragm, said chamber and both sides of said diaphragm having direct communication With the atmosphere, such communication from the rear side of said diaphragm being through an opening around said diaphragm, said opening being unrestricted in its direct communication with the atmosphere and of a predetermined size to responsively balance the air resistance in said chamber to the Vibration of said diaphragm whereby a full range of audible frequencies is reproduced, said opening being of a larger diameter than said diaphragm.

2. A sound apparatus comprising a chamber of determined volume, a sound unit in said chamber including a vibratile diaphragm, said chamber having an opening providing free and unrestricted communication With the atmosphere, said opening being of such predetermined size and of a diameter greater than said diaphragm so as to responsively balance the air resistance in said chamber to the Vibration of said diaphragm whereby a full range of audible frequencies are reproduced, and said diaphragm being so disposed with relation to said opening that there is provided a free and unrestricted passage for the sound Waves from all parts of said diaphragm to the atmosphere through said opening.

3. A sound apparatus comprising a chamber of determined volume, a sound unit in said chamber including a Vibratile diaphragm, said chamber having communication with the atmosphere directly from both surfaces of said diaphragm, and means in said chamber for Varying the volume of said chamber.

4. A sound apparatus comprising a chamber of determined volume, and a sound unit in said chamber including a vibratile diaphragm, said chamber having communication with the atmosphere directly from both surfaces of said diaphragm, and means in said chamber for varying the volume of said chamber, comprising removable panels slidably mounted therein.

5. A sound apparatus comprising a closed box having a single opening therein providing direct and unrestricted communication to the atmosphere, a loud speaker diaphragm in said box adjacent said opening of less diameter than said opening, the space between said diaphragm and said opening providing a direct and ree passage to the atmosphere, and separated baiile members in said box disposed adjacent a portion only of said diaphragm and spaced rearwardly of said opening and the portion of said diaphragm adjacent said opening.

LEO J. BUCKLEY.

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