US1418998A - Diaphragm for sound-producing instruments - Google Patents

Description

S. B. WILUAMSON. DIAPHRAGM 'FOR SOUND PRODUCING INSTRUMENTS.

APPLCATION FILED OCT.20, 1920.

Patented June 6, 1922.

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UNITED STATES SAMUEL B. WILLIAMSON, OF WESTPORT, CONNECTICUT.

DIAPHRAGM FOR SOUND-PRODUCING ;[NSTRUMEiN'TS.

Speciflcation of Letters Patent.

Patented June 6,1922.

Application filed October 20, 1920. Serial No. 418330.

To all whom it may concem:

Be t known that I, SAMUEL B. WILLIAM- soN, a citizen of the United States of America, and a resident of. Westport, County of Fairfield, State of Connectic'ut, have invented certain new .and useful Improvements in Diaphragms for Sound-Producing Instruments, of which the following is aspecifi'cation. 4 w

One of the objects of my invention is to provide a diaphragm which is very delicate and responsive in its nature so as to take up the vibrations of the sound initiatin'g instrumentalities and likewise equally delicate and accurate in reproducing same.

Another object of my invention is to so form the diaphragm as to eliminate to a gr'eater degree than heretofore attained the nasal qualities of the voice and at the same time to do away with all scratehy noises; and in carrying this phase of my improvement into efect I provide a sound screen, or sifter, integral with, and midway of, the diaphragm structure, which will arrest and eliminate these undesired vibrations and permit the undiluted ori inal 'tones to arrive at, and departfrom, the outer, or sound, delivering surface.

I further in my invention and improved diaphragm contenplate and attain a much greater vibratory activity than heretofore achieved in any similar instrumentality of like dimension; in fact I secure an amplitude of vibration equal to that which would ordinarilybe obtained in a diaphragm of four or five times the area; that is under present con structions.

Another, and very important, object secured by me in the engineering of ny preseut improvement s that I provide a structure which will secure the harmonious reproduction of orchestras, so that the orchestra, as a whole, is truly and accurately reproduced and the accentuating of any special instrument is entirely avoided.

Another object of my invention, which I will hereinafter explain at large, is the separation' of the sound producing zone of my diaphragm from that part of the diaphragm whi 'li is attached to its supports; and in this way and through this arrangement the diaphra gm is permitted to vibrate unhampered and unhlndered by .its supporting agencies:

thegreat difliculty experienced in this re-.

spec-t was, and is, that the diaphragm, in vi bratng, transmtted part of its activities to 'the box, or container, which latter would thereupon set up a sympathetic and more or less independent action resulting in Conflicting sounds: in creating zones, as I will explain, I am enabled to intervene and entirely obviate this drawback. In order to achieve this I will here state, although I will explain it more fully further on, that the structure which receives sifts and reproduces the vibration must be, as a unit, integral,- that is to say, homogeneous: a built-up or laminated diaphragm always results in individually developed vibrations and consequent interfering and discordant sounds. The laminations meddle with one another and instead of amplifying and clarifying the sounds serve only tomuddle and befog: a thiek instead of a clear sound; a burr instead of abell.

Specifically I provid a cylindrical diaphragm formed of fibrous paperwith a suiti able binder so blended and disposed as to result in a homogeneous mass, and `on both faces of the diaphragm I impose a suitable coating` of very fine glue. v

In constructing my diaphragm I provide a relatively large centrally located vibrating zone. This zone is as hereintofore indicated, formed of fibrous material with a suitable binder and a coating on each face; it is my desire and purpose to limit the vibrations to this central zone and not permit them to be communicated to the box or case of the phonograph: to achieve this I provide a concen tric zone immediately outside of and conti guous to the central zone of a conforrnation which will operate to halt and cut off the sound vibratious. and I accomplish this by effecting a compression of the material so that when the vibrations proceeding radially outward from the center of the disc reach this 'depressed portion 'they will not get across: in other words this is a dead nonvibrating annular moat which refuses passage to the progress of the vibrations.

The outer edge or periphery of the dia phragm'may be formed in various ways a: I

will explain, but I cannot too strongly accentuate the necessity and importance of the annular noat atoresaid. v

This depression or moat also serves to delimit the vibrations and prevents them creeping, and it also in a sense is a sort of hinge for the outer edge ot' the central zone.

Referring to the accompanyiug drawngs which form part ot' this specificatiou,

Figur-e l represents a view partly insection of a phonograph instrument.

Figure 2 indicates the same inplement on the line lI-II Figure l.

Figure 3 is a cross section of my improved diaphragm as it is shaped preliminarily.

Figure 4 is a similar View of the diaphragn after it has been treated with the coating material.

-Figure 5 shows the conformation ot' the diaphragm after it has been subject to compression: in this View appears the main central vibrating zone, the depressed concentric zone surrounding same which depression is designed and intended for shutting of and stopping the outward radial travel ot' the vibrations of the central zone thereby preventing said vibrations from reaching the phonograph case or box and setting up independent and confiicting vibrations; in this view is also shown the outer or pe'ipheral zonepo'sitioned in the complete 'structure to be embraced and held in position by the diaphragm supporting agencies of the phono-' graph case. In this figure also I show the central perforation designed to receive the needle arm.

Figure 6 represents the diaphragm with the immediate 'supporting agencies consisting of the peripheral rings; this view also shows the central attachment.

Figures 7 and 8 show modified forms of diaphragms.

At 12 is the peripheral rim which in cross section is full size, the same size in cross section as the central zone 13. Between the central zone 13 and the peripheral rim 12 is the annulardepression 14 positioned concentric with the central zone and formed by pressing in upon the diaphragm from both sides. This annular depression 14 is arranged in the outer portion of the diaphragm and contiguous to the final outer rim 12. The physical efi'ect of this distribution of zones is that when the central area becomes agitated by the needle arm the amplitude of the resulting vibrations of the diaphragm will be greatest at the central point, the vibrations tending to decrease as they approach the peripheryz nevertheless at the periphery 'there will be some activity which if unsuppressed will be communicated to the parts of the phonograp'h structure which serve as peripheral supports; this latter defeat, which attaches to all present forms of phonographs, I purpose eliminating by means of the depression 14 for when the radial travel of the vibrations, moving from the central point outwards, reach this depression they are halted as said depression by reason ot' its position and inherent rigdity will operate as a stop; the -vibrations in other words will not get across the zone 14.

In Fgure T I show a modifiedform of depression; here the annular groove is on one side of the disc only: in Figure 8 is another form: in this instance it is a sort of platform 16. The principle in all of these is the same however and that is a wave stop between the central vibrating zone and the phonograph box.

At 17 is the central perforaton to accommodate the screw 18 for attaching the needle arm 19.

At 20 are peripheral rings of rubber or other suitable material and these latter embrace and retain the disc at its outer edge.

At 21 is the needle held in the needle arm 19 by adjusting screw 22 and at 23' is shown the record disc. These latteriare conventional forms and need not be enlarged upon.

Having thus described my invention the following is what I claim as new and useful therein and desire to secure by Letters Patent.

l. A circular sound producing diaphragn 95 formed throughout of fibrous material with a compressed concentric zone between the center and periphery.

2. A sound producing diaphragn formed throughout of homogeneou-s fibrous material 100 and comprisinga main central portion and a p concentric compressed depression positioned between the periphery and the center.

3. A sound producing diaphragm formed throughout of honogeneous fibrous material and comprising a main central portion and a concentric compressed depression position'ed relatively nearer the periphery than the center.

4. A sound producing diaphragn for-med 110.

throughout of fibrous material, and comprising a main central rin-compressed vibrating zone, and a concentric zone positioned relatively near theperiphery sufliciently compressed to permit independent vibrating acllv tivities of the central zone.

5. A sound reproducing diaphragm formed v throughout 'of fibrous material, and comprising a main central uncompressed vibrating zone, 'and a concentric compressed de- .pression positioned exterior to the said main material, and comprisng a main central iribratmg. zone, wth a concentrc exteror zone of greater densty than the central zone.

8. The method of making diaphragms for 5 sound pmducing instruments which consists in providin a cylindrcal disa of fibrous paper having a nder so blended and disposed as to result in a homogeneous mass, applying on both facesof the diaphragm a coating of very fine glue and finally b compression forming a zone of diminshe crosssection contiguous tothe periphery of the diaphragm. V

. SAMUEL B. WILLIAMSON.

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