US238740A - Acoustic telephone - Google Patents

Description

(Model.)

H. WILLARDI Acoustic Telephone.

No. 238,140. A A Patented March 8,1881.

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UNITED STATES PATENT GEEICE.

HENDERSON WILLARD, OF GRAND RAPIDS, MICHIGAN.

ACOUSTIC TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 238,740, dated March 8, 1881.

Application filed November 19, 1880.

To all whom it may concern Be it known that I, HENDERSON WILLARD, a citizen of the United States, residing at the city of Grand Rapids, in the county of Kent, and State of Michigan, have invented certain Improvements in Acoustic Telephones, of which the following is a specification.

This invention relates toacoustic telephones in which a line ot' wire connects two vibrating diaphragms, either of which may receive or transmit sound.

The said invention consists, principally, in the combination, with each diaphragm, of a niouth-and-ear piece having its rear t'ace in contact at all points with the front of said diaphragm, in order to 4insure clearness and accuracy of sound.

1t also consists in constructing each mouthand-ear piece with an inwardly-tlaring passage or chamber having straight sides inclined at an angle, which will cause all sound-waves received therein from the diaphragm to be reliected forward through the open front of the instrumentwithout returning` to the diaphragm or the neighborhood thereof.

It consists, finally, in the special devices for supporting the connecting-wire, and in certain other improvements hereinafter set forth.

In the accompanying drawings, Figure l represents a vertical section through one of the transmitting or receiving instruments, arranged with its mouth-piece upward; and FiO. 2 represents a side view of a part ot' the connecting-wire and the devices for supporting the same.

A designates one of the receiving or transmitting instruments, (it being adapted to either use,) which consists of a case inclosing a broad rear sound-chamber, a mouth-piece or ear-piece, B, and a diaphragm, C, that separates said chamber from the interior ot' said mouthpiece. Said case preferably consists of a front part integral with said mouthpiece, and a rear part, A', secured to said front part by screws h It. A transmitting or connecting wire, G, is attached at one end to one ot' said diaphragms and at the other end to the other, the attachment being made in each case by means of a button, d, on the front of the diaphragm, and an eye, O, at the rear of the latter, said eye having a shank, which passes (Model.)

through said diaphragm and screws into said button.

The general construction of the telephone, as above indicated, is not broadly new; but hitherto there have been spaces, chambers, or recesses interposed between the front of the diaphragm and the rear portion or base of the mouth-piece. Now the said mouth-piece becomes an ear-piece when the instrument is used for receiving a message, and there ought to be perfect clearness, distinctness, and purity of tone in the messages received through it. Such air chambers,spaces,or recesses between any part of the diaphragm and the rear wall of the mouth-piece will inevitably cause a certain inequality and unreliability in the vibrations of the diaphragm and a partial deadening of tone and confusion ot' sound. To obviate this serious defect l have caused the rear wall or base, b, of my mouth-piece (it is also the front wall of the casing A) to tit at all points squarely against the front face of diaphragm C, said diaphragm being attached near its periphery to said wall b by tacks n or other convenient fastenings. Then the soundwaves passing through wire C reach diaphragm C they are transmitted, by the central portion of the latter, to the space or passage within the mouth-piece without any loss of 8o tone or confusion of sound. The wall b adbrds at all points, except within the central opening, a solid brace or backing for said diaphragm.

The construction oi' my mouth-piece is another important feature ot' my invention. This mouth-piece (or ear-piece) consists of an outwardly-flaring part, f, and an inwardly-flaring part, ff', which form a shell or casing for two communicating chambers or passages, f j", which have the shape oftruncated cones placed with their lesser ent s together, so as to form a neck, fm. The outer chamber, j", has a wide tlare, so as to accommodate a persons mouth or ear readily and fully. Theinner one ares less, the sides having such an inclination that the waves of sound thrown against the same, by the action of the diaphragm in receiving, will not be reliected back to said diaphragm nor across from side to side, but out of the instrument through the neck fm and the chamber or passage f. This avoids the confusion IOO and indistinctness of sound due to vibrations from side to side of the ear-piece B and back toward diaphragm O, which must inevitably arise when the chamber corresponding to f has curved walls, or even straight walls of too great an inclination. The curved walls are, however, more objectionable than these last, since they tend to concentrate or focalize the sound-waves on the center of the diaphragm.

In sending` a message a part of the soundwaves caused by the voice will be reected by the inclined sides of space f through neck fm against the inner face of the wall off', whereby they will again be reflected in converging lines on the center of the diaphragm, so as to strengthen the sound without confusing it. Another portion of the sound-waves will pass directly through neckf/H to diaphragm C without any reiiection whatever. Said diaphragm consists of two wooden strips or veneers, a and a', arranged with the grain of one crossing that of the other. This cross grain arrangement lessens the liability to warp or split. Two strips, united as shown, give greater elasticity and resonance than a single piece of equal thickness. I t-hus combine in my diaphragm the highestdegree of durability and resonance consistent with a given quantity ofthe proper material.

To prevent sagging of the line-wire C', and impediment of longitudinal vibrations therein, and to maintain equality of tension at all points, I employ a number oi' supportingsprings therefor, hung at suitable intervals, and having the construction shown in Fig. 2. Each of these springs has a central eye, y, and two arms, s s', that extend therefrom in opposite directions, the whole being formed from one bar of spring-wire. Eye y is suspended by a wire, l, from any suitable iixed device, and the ends of arms s s are connected, by suspending-wires x', to two diiierent points on line-wire C', said line-wire being free, however, to slide through eyes or loops formed on the lower end of said suspending-wires. Arms s s tend constantly to rise into the position indicated in dotted lines, thus lifting said wire and maintaining it everywhere under equal tension. If the spring-support were at one point ofthe wire only the angle formed there in would necessarily be more acute than those formed by my double spring-support above described, and the transmission of the sound would be more or less impeded thereby.

Having thus described my invention, what I claim is- 1. The combination of a diaphragm for transmitting and receiving sound with the rear face ofthe base of the mouth -and-ear piece, the greater part of said diaphragm being in contact with said rear face, for the purpose set forth.

2. In combination with a diaphragm for rcceivin g and transmitting sound, a mouthandear piece having its interior formed ot' two straight solid communicating conoidal chambers, substantially as set forth.

3. A spring-bar, forming loop y, and arms s s', in combination with line-wire C and sus pending-wires Z m w.

HENDERSON VILLARD.

Witnesses:

EDWARD TAGGART, HENRY H. GIBSON.

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