US1808512A - Sound radiating apparatus - Google Patents

Description

June 2, 1931. L. sHAPlRo 1,303,512

soUND RADIATING APPARATUS Filed June 16. 1928 l l I l l mvENToR 8%@ ATTORNEYS Patented June 2, 1931 PATENT OFFICE LAZARUS SHAPIRO, OF NEW YORK, N. Y.

SOUND RADIATING APPARATUS Application led June 16, 1928.

This invention relates to sound radiating apparatus and for purposes of illustration is herein shown and described as embodied in a radio loud speaker. It will be appreciated, however, that the invention may be utilized for other purposes than radio reception, as, for example, in phonographic reproduction or in connection with the reproduction of sounds or signals transmitted by wire.

It is now usual practice to provide in an apparatus of this character a centrally driven vibrating member of substantial dimensions such as a cone of paper or other vibrant material for radiating the sound vibrations derivable from a driving device operated by electrical undulations or other suitable means.

It is important for the purpose of obtaining uniform response to notes of different frequencies and also for the purpose of avoiding strains due to varying condition of temperature and humidity that the position of the vibrating member in the direction of its vibration be determined solely by the driving device and that its marginal portion be free from rigid support or connection to other parts, so that it may shift bodily, without strain, in response to changes of operating conditions. It is desirable, however, that provision be made for engaging the outer or marginal portion of the vibrating member in a non-rigid manner by soft, yielding means to provide lateral support and to damp the vibrations of the vibrating member at its free edge for the purpose of preventing objectionable parasitic vibrations of the edge which might give rise to the familiar paper rattle, and also to reduce the production of undesirable differences in amount of response at different frequencies which would otherwise result from the resonance characteristics of the vibrating member. It is also important to prevent the passage of air around the edge of the vibrating member and hence to make provision for impeding or baffling the passage of air from one side of the vibrating member to the other, because the ready passoft, yielding, material such as sponge rubber sage of air results in a marked decrease in the amplifying efficiency of the vibrating member, particularly at low frequencies.

To these ends it is an important feature of plie within the opening of the front Wall Serial No. 285,796.

Vthe present invention that provision is made of a vibrating member longitudinally supported and driven from the center thereof,

.a baffle surrounding the vibrating member Vadapted to have the peripheral portion of the vibrating member embedded therein, for the purpose of forming a seal between the vibrating member and the bale.

Other objects and advantages will hereinafter appear.

In the drawings forming part of this speciiication:

Fig 1 is a longitudinal, vertical, sectional view of an apparatus embodying the invention; and

Fig. 2 is a front elevation of the same apparatus.

The apparatus comprises a box 1, open at the rear end thereof and having lateral walls including a top 2, bottom 3, and side Walls 4. A front wall 5 is provided with an opening, illustrated as circular but which may be of any suitable shape to correspond to the shape of the vibrating member. A bar 6 extends horizontally across the back of the box and carries an electrically driven motor unit for translating electrical undulations into sound vibrations. Such unit may be like that disclosed in Letters Patent of the United States No. 1,666,183 granted to me on April 17, 1928, and comprises a drive rod '7 for lonl gitudinally supporting and driving a vibratof the conical washers 11 and the split chuck 9. Y 1

The conical vibrating member 8 is positioned to have its marginal or edge portion 5 of the box 1.

Provision is made of a band or ring 12 of lining the opening in the front wall 5 and engaging the edge of the cone completely around the periphery thereof. Such material ldeeper notes,

is suiiiciently resilient to substantially follow the Vibration of the vibrating member to prevent paper rattle but has no tendency to sustain vibrations, being rather shock-absorbthe baffle. This feature is of ver-y great imsecuring the full value of the since without it sound radiation at low frequencies would be impaired by 1mportance in `mediate neutralization of the rarefactions and compressions of air on opposite sides of the cone.` 'Y

In addition to thus providing a seal the ring I2 provides a cushioning or damping support for the periphery of the cone preventing paper rattle and reducing the peaks corresponding to the resonant'frequencies of the vibrating member. It will be observed that the normal functoning of the cone by longitudinal movement results in a shearing deformation ofthe soft compressible ring 12.

The cone is not attached to the ring 12 but simply sinks into it due to the yielding nature of the material forming the ring. rlhe cone is not, therefore, held against bodily shifting, but may adjust itself relative to the ring lin response toV variations of temperature, humidity, or other factors, and will never be put Y under unnatural strain by suchfactors.

Although in the illustrative form of the invention the ring 12 is shown tangential to the y lateral circumference of the cone, it will be understood that the ring may be positioned in V abutting relationship to the forward edge of the cone or be positioned to encircle the cone slightly in the rear of its forward edge.

The sealing and damping of the kedge of the Vvibrating membermay be eected by other means vthan sponge rubber. For example, a

piece of soft Vrubber tubing or other yielding, non-vibrant means may be employed.k

It will be understood, moreover, that the vibrating member may be of any desired form I claim:

1. In a sound radiator, in combination a vibrating member, driving means therefor, a baffle surrounding said member, and a ring of soft, compressible, non-vibratory material sealing the space between the member and the baiiie and having its inner diameter a little less than the maximum diameter of the member, the peripheral edge of said member engaging the linner circumferential face of the ring. Y

2. In a sound radiator, in combination, a vibrating member, driving means therefor, a baille surrounding said member, and a ring of sponge rubber sealing the space between the member and the baffle, the peripheral edge of said member engaging said ring, but unattached thereto, whereby said edge may embed itself in the ring and the member may shift bodily relatively to said ring without reduc-f ing the sealing effect of Vsaid ring and without setting up any vibrations therein.

3. In a sound radiator, in combination, a conical vibrating member, driving means therefor, a baffle housing said member andfgo having a forward, radiating end surrounding the vibrating member, and a solid ring of soft, compressible, non-vibratory material disposed between the peripheral edge of said ,member and the radiating end of said baflie, the peripheral edge of said member being Vembedded m and unattached to said ring and free to move bodily relative thereto.

In testimony whereof I have amxed my signature to this'specilication.

Y LAZARUS sHAPIRo.

and material other than the conical paper Y type of member illustrated herein.

i While I haveillustrated and described in detail' certain preferred forms of my invention, it is to be understood that changesfmay be made therein and the invention embodied in other structures. I do not, therefore, de-

Vsire to limit myself to thespe'cific constructions illustrated, but intend to cover my in- .vention broadly in whatever forml its principle may be utilized.

V'ils i ias Yiso

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