US322295A - Acoustic diaphragm - Google Patents

Description

(No Model.)

' W. JONES & W. W. REYNOLDS.

ACOUSTIC DIAPHRAGM.

No. 322,295. Patented July 14,1885.

L1 yen for a N. PETERS. PholoLilhcgnph-r. Wnhingtnn. D.C.

\VILLIAM JONES AND \VARREN -W. REYNOLDS, OF CiiSSOP-OLlS, liil'CillGlrhT.

ACOUSTlC E lAPHRAGhd.

SPECIFICATEON forming part of Letters Patent No. 322,295, dated July 1%, Application filed December 13, 1884. (No model.)

To aZZ whom it may concern:

Be it known that we, WILLIAM J ONES and \VAnnnN W. REYNoLDs, citizens of the United States, residing at Oassopolis, in the county of Cass and State of Michigan, have invented a certain new and useful Improvement in Acoustic Diaphragms, which has not been patented to ourselves, nor to others with our consent or knowledge, in any country, and which has not, according to our knowledge and belief, been in public use or on sale in the United States for more than two years prior to this application; and we do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawing, which represents a diametric section of one of our improved diaphragms, the thickness being considerably exaggerated for the purpose of showing the more distinctly the several layers of which the diaphragm is composed.

Our invention relates to acoustic diaph ragms of that kind which are used in telephones; and its object more particularly is to provide such a diaphragm which shall, in conjunction with another similar diaphragm and awire or cord connecting the two, and without the aid of any electric or magnetic apparatus, be capable of transmitting the utterances of the human voice or the sound of musical instruments with perfect clearuess to the distance of a mile or more.

To this end it consists in a diaphragm composed of a layer of wood. and one or more layers of paper, preferably with the addition of one or more layers of canvas or equivalent material, the whole compacted into a single plate. We will proceed to describe this in detail, and will afterward point out particularly and distinctly what we claim as our invention. W'e make the diaphragm of the usual disk form and of two or more circular layers closely applied the one to the other, so as to form one perfectly-compact disk. For this purpose we apply a cementing substance between the layers, preferably either glue or varnish; but any means by which the layers can be effectually compacted togethersuch as compression-wi.ll produce a diaphragm equally eilicient in transmitting sound. The

layer atthe front of the diaphragm nearest to the hearer or speaker, as the case may be, is of wood, ordinarily a veneer from one ihirtysecond to one-sixteenth of an inch thick, and it is on this layer that we principally depend for reproducing the sound vibrations, the lesser thickness being the more sensitive. The wood, however, when used alone, gives out a whizzing sound characterisiic of the material, which, besides being disagreeable, mingles confusingly with the sound which comes from the voice of the speaker, and thus makes the reproduction indistinct. We reduce i peculiar whizzing sound to practically noth J by adding to the layer of wood a layer of pa per, )referably paper made of wood pulp and about equal to the wood in thickness. diaphragm thus composed does excellent service as a transmitter of speech; but as it is hardly strong enough to bear for any length of time without detriment. the tension of the connecting-wire, except where the line is comparatively short, we add, to give i mness to the structure, a sheet (corrcspei g in shape to the other two layers) of canvas or other cloth, whose thickness is not appre ble by ordinary means of measurement. "We apply it between the wood and the paper. Rawhide, wire-cloth, or any thin and iirm fabric or membrane may be used instead of the canvas.

W'e find in practice that the best results are attained by adding to the structure, as we have already described it, another layer of canvas or its equivalent and another layer of paper, the latter being also of about the same thickness as the wood.

This the preferable form of our improved phragni is the one illustrated in the awing. In this A denotes the button, of wood, metal, or other suitable material, attached. to the front or outer face of the diaphra m by any convenient means. 13 denotes the wire, hastened at its end to the button and passing through diaphragm to a similar diaphragm at the other end of the line. C denotes the outer or front layer of the diaphragm, being a disk of woe veneer from one-thirty-seooml to oi'ze-si":ccn:n of an inch thick. D denotes the two layers of paper, each similar in shape and thickness to the wood; and E denotes the two sheets of canvas or equivalent material interposed, respectively, between the wood and the first layer of paper and between the two layers 01' paper. Of course we apply a suitable moutlrpiece to the front of the diaphragm; but as a mouthpiece forms no part of the present invention, and is unnecessary to a perfect understanding of it, we have not shown any mouth-piece in the drawing.

\Vith the diaphragm which we have illustrated we find by actual use that articulation is perfectly reproduced, and the tones of each individual voice are rendered with purity at a distance of seven-eighths of a mile from the speaker, there being several sharp bends of the wire between the two termini of the line,

and we believe that the apparatus will transniit speech distinctly to a much greater distance.

brane arranged, respectively,between the wood 0 and the paper and between the two layers of paper, and a cementing material, substantially as and for the purpose described.

XVILLIAM JONES. UXRBEN \V. REYNOLDS.

Witnesses:

THOMAS H UGGINS, GEORGE H. Rnnrrnrn.

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