US252142A - Self as trustee - Google Patents

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US252142A US252142DA US252142A US 252142 A US252142 A US 252142A US 252142D A US252142D A US 252142DA US 252142 A US252142 A US 252142A
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    • H04R19/00Electrostatic transducers
    • H04R19/01Electrostatic transducers characterised by the use of electrets
    • H04R19/016Electrostatic transducers characterised by the use of electrets for microphones


A `(No Model.) Y 2 Sheets-Sheet 1.
"N0.2.52,142. 'Patented Jan.' 10.1882..A
(No Model.) 2 Sheets-Sheet A; W. ROSBL C. ACHEEVER.
ELECTRIC SPEAKINTELBPHoNE- Q Y No.,252,142. Patented Jam10.1882.v4
ALLEN WJROSE AND CHARLES p ApcnEEvER, on NEW YORK, N. Y., SAID y ROSE ASSIcNoR To sAID cnEEvER, SAID cnEEvER ASSIGNOR To HIM- I sELE As TRUSTEE` sPEcIEIcA'I:10NramingV part eeA Lettere rfatent' No. 252,142, dated January ro, 1882.
" Application tledNovember 1"2,`18`80`.` (No model.)
To all/whom it may` concern 1 Beit known that wen/ALLEN` `W. ROSE, a citizen of theDominion of Canada, residing-in the city, county,and State of New York, and 5 CHARLES A.GHEEvER,a citizen of the United States, also residing Ain New `York city aforesaid, jointly Ahave invented certain new and useful Improvementsin `Electric Speaking-Telephony, of which the following ds a specification. A Our inventionis based upon and, constitutes an improvement upon certain new and useful improvementsin electric telephony made by the aforesaid ROSE, the distinguishing characteristic of which is the suspension of magnetic filings in the magneticleld of a speaking-telephone, throughwhich field a galvanic current passes. t
In another application made by us jointly 2o for Letters Patent of the United States we have `shown an improvementnpon the said "ROSEsinvention, which improvement consists in suspending` thetilings in a magnetic field through which the current, when the telephone 2 5 is used as areceiver, does notnecessarily pass,
the magnetism acting inductively on the iii` ings in suchcase.
'Ihe object of ourpresent invention is to dis` pense with a permanent magnet or the equiv- 3o alent core of an electro-magnet, substituting therefor theinductive action ofan `ordinary coil or helix included in `an ordinary electric circuit. d The subject-matter claimed is hereinafter speciied.
Our invention may be `modified in various ways, of which the accompanying drawings furnish the best illustra-tions now known to us.
Figure l represents a central longitudinal section through an apparatus adapted for op- 40 eration both as areceiverand asatransmitter,
the current lowingfrom the ground through` i the batteryB over the line Z,and through a heliX or flat spiral, C, of ordinary insulated wire, through thcwire l', which is connected with the sheet (Hof conductingmaterial,preferably non-magnetic-such,for instance, as tin-foil or .1 `sheet-brass.` -The current iiows through this coiland conductin g-surface, magnetizes the lings or powderF of some magnetic materialsu ch as iron ,steel,alun1inium,cobalt, or nickel- `in the magnetic iield between the conductingsurface C' and the diaphragm D, causing the filings to stand upright and establish connection with the plate or diaphragm D, which is of non-magnetic conducting material, connecting with the line-wire L.
In operation as a transmitter the diaphragm is vibrated hysound-wave`s,which in turn produce correlated changes or variations in the lings, and consequently in the resistance ot'` 6o the circuit or the strength ofthe current Howing therethrough, which variations may be reproduced'in any of the well-known forms of receivers connected with theline wire, and thus accurately reproduce articulate speech `as to tone, pitch, and quality. If two such instru- `ments asthose above described were placed upon the line, the variations in the strength of the current caused by the sound-vibrations ot' the transmitter would be accurately reproduced Iupon the other, the apparatus being equally well adapted for use as a transmitter and as a receiver.` When used as a receiver the current passes from the line through the diaphragm and filings to the conducting-surface C', wire l', coil C, and wire l, to the ground,ior,` `in other words, in a direction exactly the reverse of that in which it passes when acting as a transmitter. The variations in the strength of this current caused by the sound-vibrations of the transmitter produce corresponding va` riations in the magnetic field of the receiver by passing through its helix C, and thus cause correlated movements in the filings, which are correspondingly reproduced upon the diaphragm and converted into sound-waves.
In order to keep the magnetic filings in a proper condition, we prefer, though it is not necessary, to connect the diaphragm D and conducting-surface C by a substance of high resistance relative to the things-such, t'or instance as a ring or slip of oilestone, O, pro` vided with a conducting-surface of carbon or plumbago, or of a strip of carbon or other paper covered with powdered plumbago.
Fig. 2 represents a vertical central section through the apparatus organized for transmission only, the coil C in this case being provided with a local battery, L B, for keeping it charged. The line'passes from the ground and main battery through the wire l to a conducting surface or plate, G', similar to that above described, through the magnetic tilings F and diaphragm D to the linewire L.
Fig. 3 represents a vertical central section through one form ot' our improved apparatus organized for use as a receiver only. The current from the transmitter passes through the line-wire Lto the coil C, and thence to the ground through the line l. The variations in the strength of the current thus transmitted are reproduced upon the ilings in the manner mentioned above. It is obvious that under this organization it is immaterial whether C be a conducting-surface or not. In this instance a ring, b, interposed between the surface G and the diaphragm, prevents the esca-peot' the iilings when not subject to magnetic action, and some equivalent protection is preferably' employed in all of the forms of the apparatus. We find it advantageous in this form of apparatus to employ a local circuit provided with a local battery, L B, to keep the coil charged, as described in Fig. 2; but to prevent tlhe short-circuitiug of the current from the transmitter we interpose a resistance, R 7L, greater than that of the coil employed, in the local circuit, and a switch, S, ot' ordinary coustruction, may be employed to throw this line out of circuit when required.
Fig. 4 represents a vertical central section through an apparatus adapted for operation both as a receiver and as atransmitter, in connection with an induction-coil and a locallycharged circuit such as above described. W'e may remark here that any ot the instruments herein described could be used in connection with an induction-coil in well-known ways, and with or without a separate local circuit for charging the coil.
Fig. 4 shows the primary wires of an induction-coil, (in which is included the local battery L B in the ordinary way or" telephonie transmission,) connected one with the conducting-surface Gand the other with the diaphragm D, the circuit being completed through the lings. Thesecondarycircuitoftheinductioncoil to which the line-wire is connected passes through the inducing-coil G, in the usual wellknown way, to the ground. This inducingcoil is shown as composed ot' two separate coils, each in the form of a dat spiral, and one placed upon the other. We prefer to carry the linewire connections through the coil nearest the conducting-surface C', while the other is included in the charging-circuit provided with the local battery L B, thus obviating the ne cessity for the employment of the resistance coil or switch incident to the construction shown in Fig. 3. As the coils are separate, there is no danger of short-circuiting the linecurrent. The arrangement of the two coils may obviously be varied in wellknown wayssuch, for instance, as winding them alternately in the same plane, so as to constituteadouble spiral.
Fig. 5 shows a section through a coil of this latter construction.
We do not claim herein the method of operation ot' the devices described, nor the combination of the electric circuit, an inducing-helix without a core included therein, a local battery included in a local circuit connected with the helix, a resistance in said local circuit to prevent short-circuiting the main line, a diaphragm, and magnetic filings interposed between the inducing-helix and diaphragm, as these subjects-matter will be embodied in another division of this application.
Ve claim as our invention- 1. The combination, substantially as herein set forth, of an electric circuit, a battery, an inducing-helix,anon-magneticconducting-surface, a diaphragm, and magnetic filings interposed in the magnetic tield between said con,- ducting-surfaee and diaphragm. l
2. The combination;substantially as herein set forth, of an inducing-helix, a conductingsurface, a diaphragm, magnetic lings interposed between the helix and diaphragm, -and a high resistance between the diaphragm and conducting-surface to maintain the continuity ofthe magnetic circuit.
3. The combination, substantially as herein set forth, of the local circuit, its battery, the inducing coil without a core in the local circuit, aud the magnetic filings, whereby the tilings are'maintained in a constant field.
4. The combination, substantially as herein set forth, ot' an electric circuit, a conductingsurface, a diaphragm, and magnetic filings interposed between the conducting-surface and diaphragm, with an inducing-coil and an independent battery and local circuit for keeping the coil charged.
5. The combination, substantially as herein set forth, of an electric circuit, a battery, an-
inducing-helix without a core-in said circuit, a diaphragm, and magnetic filings interposed between the inducing-helix and diaphragm, the filings being acted upon iuductively by the helix and the diaphragm being vibrated by the movement of the lilings.
6. The combination, substantially as herein set forth, of two independent but adjacent iuducing-coils without cores, a diaphragm, and magnetic filings interposed between said diaphragm 'and coils.
magnetic IOO IIO
7. The combination, substantially as herein set forth, of a local circuit, its battery, an inducing-coil without a core for maintaining a constant magnetic ield, a conducting-surface,'
a diaphragm, magnetic lings interposed between the helix and diaphragm, a local bat- In testimony whereof we have hereunto subtery in the primary circuit of an induction-coil, scribed our names this 22d day of October, A. 1o in `which primary circuit the magnetic lings D. 1880.
are included, the seconda-ry helix ofsaid in- A. W. ROSE.
5 duction-coil constituting a portion ofthe line- UHAS. A. CHEEVER.
`Wire,vand an independent inducing-coihalso Witnesses: included in the line-wire7 in proximity to the WILLARD L. OANDEE,
local inducing-coil. E. C. DAVIDSON.
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