US1250192A - Telephone repeating instrument. - Google Patents

Description

C. D. LANNING.

TELEPHONE REPEATING INSTRUMENT.

Patented Dc. 18,1917.

3 SHEETSSHEET 1 APPLICATION FILED AUG-2. I911.

Inventor Chartesllbauru' C. D. LANNING.

TELEPHONE REPEATING INSTRUMENT.

APPLICATION FILED AUG-2. 1911.

1,250,192. Patented Dec. 18, 1917.

3 SHEETS-SHEET 2- witnesses Invania r Charleslllmwmzng, aa/pfi'fim. a?

C. U. LANNING.

Patented Dec. 18, 1917.

3 SHEETS-SHEET 3.

i Te

?5 O is) 9 It I A Zfivhzessea. ventar' wv/%@ WeamsDLanuiu UNITED STATES PATENT OFFICE.

CHARLES I). LANNING, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO ODIN B. ROBERTS, TRUSTEE, OF BOSTON, MASSACHUSETTS.

TELEPHONE REPEATING INSTRUMENT.

Specification of Letters Patent.

Patented Dec. 18, 1917.

Continuation of applications Serial No. 44,049, filed January 21, 1901, and Serial No. 291,530, filed December To all whom it may concern:

Be it known that 1, CHARLES D. LANNING, a citizen of the United States, and a resident of Boston, in the county of Suffolk and Commonwealth of Massachusetts, have invented an Improvement in Telephone Repeating Instruments, of which the follow ing description, in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts.

My invention has reference to instruments for repeating and thereby relaying or reinforcing telephone voice currents; and particularly to the class of such instruments embodying an electro-magnetic receiving elementand a variable resistance transmitting element controlled by such receiving element, the receiving element being con nected into the incoming line and a transmitting circuit operatively controlled by said variable resistance device being connected to an outgoing line.

In the operation of such an instrument it is obvious that there are a number of successive transformations of energy and my invention in general consists in simplifying the instrument and in so arranging it that each cooperating part may perform its desired function with efficiency, and in connecting and arranging the parts so that there will be as little energy loss as possible in the various transformations necessarily taking place and so that reproduction of the voice-current wave may be accomplished with the minimum distortion thereof; whereby the desired object may be efficiently attained; such object being the establishing of a new and stronger current in which the wave form of the received current shall be reproduced as accurately as possible.

I have illustrated my invention in the annexed drawings which are made in the various figures on slightly different scales from working apparatus of which the principal portions of the receiving and transmitting devices e. the receiving magnet and the transmitting microphone) are parts of the usual commercial transmitter and receiver respectively as used on commercial telephone lines; which will indicate in eneral the size and proportion of parts that find it advantageous to employ.

This application filed August 2, 1911.

Serial No. 641,947.

In the drawings Figure 1 is a plan View of one embodiment of my invention and Fig. 2 is an elevation partially in section of the apparatus shown in Fig. 1.

Fig. 3 is a plan view of another embodiment of my invention substantially similar to Fig. 1 except that some of the auxiliary parts therein illustrated are omitted.

Fig. 4 is an elevation partly in section of the apparatus shown in Fig. 3.

Fig. 5 illustrates another and slightly different embodiment of my invention being substantially similar to what is shown in Fig. 1 except that the position of some of the cooperative vibratory parts is relatively reversed.

Fig. 6 is an elevation partly in section of the apparatus shown in Fig. 5.

Referring to the drawings in general it will be seen that they all embody a similar mechanism for correlating the receiving and transmitting elements of the repeater. The receiving element in each case g is the usual permanent magnet with soft iron pole-pieces as employed in the commercial receiver, with its windings, y, 1 mounted on soft iron pole-pieces attached to the permanent magnet as clearly shown in plan in Figs. 1 and 3.

The magnet winding is placed in series with the receiving circuit through 11, 2, coils 3 y, 3 and o. This form of magnet is adopted for its simplicity and demonstratec efficiency. The windings are of the usual type with approximately 100 ohms resistance. The permanent magnet provides an initial field as usual, acting upon the related armature whereby the magnet is responsive differentially, and thereby cumulatively, as usual to the opposite phases of the received alternating line current.

In place of the provision of this initial field by the permanent magnet, there might be provided additional windings for the creation of this initial field by a separate battery-energized circuit of the magnet; suchmeans having been many times disclosed in the published art relating to telephone repeaters and providing in some instances a useful means for regulating the strength of th s initial flux of the receiving magnet whereby its initial strain upon the armature attached to the operated microphone may be regulated. In place thereof I provide in the various forms shown a means for regulating the gap between the magnet and related armature as will be described in detail in connection with the separate figures, but either of such means may be employed.

Operatively the magnet is fixedly mount ed on a supporting block or pediment Z". In the field of the magnet is supported a block armature p by rigid and central attachment to the vibratory electrode of the microphone. The provision of the armature in non-diaphragmatic form, that is,confin ing its function entirely to that of a responsive mag netic member, secures the maximum etli ciency in the armature as part of the magnetic circuit. Not being limited in dimen sions by considerations of flexibility it may be made as thick as desired and built in any other established manner, such as being provided with laminations or otherwise. By means of the adjusting mechanism as shown the air gap between the armature and magnet may also be established 'ata minimum distance and thus, with a magnet of ellicient design, an armature so constructed and proportioned as to be more etlicient magnetically than when limited in thickness as in diaphragms, and an air gap limited to'the smallest practicable distance, the energizing windingsbeing also as near the ends of the pole-pieces as practicable, a magnetic circuit and a receiving magnetic device of great efficiency is secured. I I

In all the forms shown the said block armature is rigidly and centrally attached to the vibratory electrode of the microphone. This microphone is provided in the form of what is known as the solidback micro phone as employed for some time past in the. commercial transmitter in the Bell service. This microphone is shown in general outline in Figs. 1, 2, '5 and G, and in detail in'Figs. 3 and 4-. It comprises, as is well understood in the art, a chamber having in the rear portion aplate carbon electrode. The front electrode is formed as part of a composite diaphragm-electrode structure; this structure being clamped upon the walls of the chamber in such manner that the diaphragmelectrode structure is maintained, preferably through granular carbonheld in said chamber between the front and back electrodes, in electrical connection with said back electrode. The diapln'agm-electrode structure is formed so that=when assembled it'has an interior plate carbon electrode and an exterior clamping member, an annular diaphragm preferablyv of mica clamped therebetween and said diaphragm being clamped upon the walls-of the chamher as above described; all'as well understood in the art and as disclosed in a prior United States patent to A. lV-hite.

In all the forms of apparatus illustrated being,

herein, said microphone is shown fixedly mounted on a pedestal. or support, which is, a-preferable but not essential construction.

It will be seen, therefore, that the armature member is separated in all forms from the vibratory electrode and diaphragm elements and also that the sin le diaphragm of the solid-back electrode structure constitutes the only diaphragmatic member involved in the vibratory operation of the con nccted armature and vibratory electrode. In this way not only is the armature provided in a design calculated to secure the greatest efficiency thereof but the vibratory,electrmt of the microphone is preserved in form, assembled, so that its freedom of movement and accuracy in performing its vibratory function, cooperating with the varying strain of the magnet, is not impaired. lVhere the vibratory electrode is subject to'the control of more than one diaphragmatic member great difliculty is found in maintaining the diaphragms in parallel alinement and'concentrically arranged; and unless such condition is preserved manifestly each diaphragm tends to restrain the action of the other and thereby the action of the microphone is much impaired.

I have provided in the preferred form of instrument herein shown as in Figs. 1 and 5 an auxiliary tension member to cooperate in the regulation of vibratory actiom'noin diaphragmatic in form, so that this dil'licult-y of adjustment and resulting impairment of microphone operation may be avoided and at the same time the single diaphragm maintained as nearly as possible in an initially flat condition which is obviously its condition of greatest delicacy as related to'freedom of vibratory movement; which auxiliary element I 'will later dc scribe.

It will be seen, therefore, that in all the forms of instruments illustrated in the drawings the ellici'ent character of the simplified repeater instrument that I have invented resides essentially in the provision of a receiving elcctro-magnetic element havingas a cooperative member thereof a block armature disassociated in function from' the vibration-controlling element of the microphone or from 'the electrode ele ment or elements of the microphonegin mounting this block armature by central and rigid attachment to the vibratory electrode; and in providing the microphone in form where its vibratory electrode is a composite diaphragm electrode structure, constituting the only diaphragm element operativ'ely related to the perform-- ance by the connected armature andvib'ratory electrode of their vibratoryfunctions. It will be obvious that'this construction, by disassociating the repeating instrument 'entirely from instruments designed to respond to or to produce audible sound, supplies a current-actuated and a current-reproducing instrument in a simple and efiicient form.

Referring to the drawings in detail, in Fig; 1 the receiving magnet 3 is mounted as shown upon a block pediment t which latter is mounted upon an adjusting carriage, the block t engaging the worm u so that the magnet may be given an adjusting movement with reference to its relation to the armature p. This worm is provided with amilled'end nut 11 and a lock nut u; the said worm u receiving a permanent and controlling end thrust from the interposed coil spring at one end thereof, u. In this form of instrument the parts are interconnect-ed sothat any increase of attraction upon the. armature p will result in increase of pressure in the microphone; and for that purpose the armature p is mounted, by means of the connecting yoke g, centrally upon the vibratory electrode structure 71 of the microphone; the said yoke being preferably made, as in the instrument shown, of aluminum so as to be as light as practicable. There is also connected to the vibratory electrode to oppose the initial magnetic strain on the, armature as communicated to said vibratory electrode, the elastic 0 which is connected at its other end to the tension adjustment means as shown comprising the worm c mounted in a pedestal as shown and carrying at its end the bracket d, supporting the hook at, the latter engaging the said elastic as stated.- Said worm e is mounted for rotative movement in said bracket d and an auxiliary rod 03 parallel to the said worm e engages said bracket d rigidly so that adjustment of said worm e by turning thereof will not disturb the alinement of the bracket (1' and hook d with reference to the said elastic c and connected hook b on the vibratory electrode structure.

The function of this elastic tensioning device is to assist. in preserving the diaphragm of the diaphragm-electrode structure initially in a flat condition, whereby the most sensitive condition thereof is secured. To perform this function the cooperative spring or tensioning device must be aperiodic in character; that is, it must have the quality inherent in diaphragms of responding accurately to the varying periods of vibration taking place in tone production and reproduction, without any dominant rate of vibration inherent in its own structure. An elastic under rectilinear extension fulfils these requirements as well or better than a diaphragm, whereas any coiled spring obviously tends to introduce its own rate of vibration and thereby impair other desired action. Such an elastic, however, may have an inherent rate of vibration at right angles to its axis of extension and for that purpose I provide the. intermediate vibration-checking member 41*, supported in contact with the elastic 0 by means of the arm n mounted in the pedestal m and held in position by the lock screw 07/.

I find the provision of this rectilinearly 7O extensible auxiliary tensioning device. preferably in the form o an elastic as slrm'n, is of considerable advantage. The reason for this is that the action of the microphone is well recognized to be that its variations 75 of conductivityare the result of variations of area of contact which latter are the consequence of varying pressure which implies movement. If the entire energy communicated to the block armature could be availed of in the form of movement-of, and pressure between the electrodes, ideal efiiciency would be secured. But in order to control the movement of the vibratory electrode and connected armature some form of mechanical vibration-controlling device is necessary in the form of instruments shown; and therefore part of the energy delivered to the armature must be expended in overcoming the resistance or inertia of this mechanical vibration controlling device. Diaphragms constitute very sensitive springs but their range of excursion is very limited; and upon very slight movement either way from a flat condition their further additional movement in the same direction is substantially restrained. Where, therefore, the diaphragm through its connected armature is under the initial strain of the electro-magnet and the current phase received by the receiving magnet is such as to still further increase the initial strain, it is substantially inoperative in producing further movement of, or pressure between, the electrodes, the energy being taken up in diaphragm resistance. If very large diaphragms are used for the purpose of enlarging the range of excursion, Variations or inaccuracies of vibratory movement creep in requiring the use of damping springs upon various parts of the diaphragm such as those commonly employed with transmitter diaphragms. The function of the auxiliary tensioning device in the form shown, therefore, is to supply a tension acting against the initial magnetic tension to keep the diaphragm of the micro phone initially in a substantially flat condition. The auxiliary device being provided as shown, is in a form having a very large range of movement relatively to the energy spent thereon, and is the equivalent in sensitiveness of a very large diaphragm. The result is that the mechanical resistance or inertia of the associated microphone diaphragm and auxiliary tensioning device is less, under the varying operating conditions, than the resistance of the diaphragm alone when initially distorted as would otherwise be the case. By providing the auxiliary tension and vibration-controlling device in this nected that any increase of attractive action" by the receiving magnet y on the armature p operates to decreasethe conductivity or the microphone. The instrument being substantially similar 'in' all respects to that shown in Figs. 1 and 2 no other description will be necessary.

In Figs. 3 and i I haveshown a form of the instrument in whlch the auxiliary vibra-f tlon controlling member is omitted. In this and '6 I have illustrated substantially the same general arrangement of form the receiving magnet is mounted on a fixed pediment' t, it being otherwise 0on strueted 'and1ts c1rcu1t connectedasabove described 1n connection wlth the other figures. The transn'iitting' microphone is mounted in a holder or pediment'r, which is carried in a support W, being mounted there- 1n on a worm r prov1ded with an end milled nut-r andlock nut r whereby the worm,

being fixedly held in'the endmembers r 0 on said support 1, may be utilized to give the microphone and" connected armature p a movement parallel with the end faces of the receiving magnet. Said support 0 in turn mounted upon the worm a carriednr the bracket to and'u", the worm to being provided w th an'end m1lled nut' a and loclrnut 10*, whereby the whole microphone and connected armature structure may be given a movement longitudinal of the microphone axis," By these'adjusting mearns the microphone and connected armature may be readily brought intoany desired position with relation to the cooperating receiving magnet and there supported and-maintained. The microphone is connected as before in-series with a -local battery circuit through the binding posts 4 and the circuit connections to the induction coils as shown, the secondaryof the induction coil being connected into the transmitting circuit as desired to the circuitsas shown and the binding posts 7 8 p The circuit connections in the various instruments are. indicated by similar marking in the various figures.

It will be seen that in the form illustrated in Figs. 3 and 4 the essential features of my arrangement are embodied, but preferably I' employ the'forms illustrated in the other figures and for' the reasons'above stated. 1

While I have herein shown and described for purposes of illustration one specific form of the invention, it is to be understood that the same is not limited to the details of construction or relative arrangement of parts but that extensive deviations maybe made from the disclosed details without departing from the spirit of the invention.

Claims: 1

1. A telephonic voice-current repeating instrument, comprising an initially magnetized receiving magnet and its circuit connections; a transmitting microphone and its in 'thefield of said magnet, rigidly and centrally attached to said diaphragm structure; together with an auxiliary vibration-controlling member for the microphone, in the form of a rectilinearly extensible member, disposed along the central axis of vibration of the microphone diaphragm, extended by means of an attachment to an abutment and to the associated armature and vibratory electrode, and opposing the magnetic pull on the armature; said auxiliary tension member, as related to the said diaphragm member, having relatively large elastic limits and having a low inherent rate of vibra tion.

2. A telephonic voice-current repeating instrument, comprising-an initially magnetized receiving'magnet and its circuit connections;'a transmitting microphone and its circuit connections, embodying a stationary rear electrode, an opposed electrode inthe form of a single,peripherally-clamped, nonmagnetic, diaphragmatic, composite electrode-diaphragm structure, electrically related to said stationary rear electrode, with the central axis of vibratory movement of said diaphragm-electrode structure substantially coincident with the central line of pull of said magnet; and a rigid block armature in the field of said magnet, rigidly and contrally attached to said diaphragm structure; together with an auxiliary vibration-controlling member for the microphone, in the form of a rectilinearly extensible member, disposed along the central axis of vibration of the microphone diaphragm, extended by means of'an attachment to an abutment and to the associated armature and vibratory electrode, and opposing the magnetic pull on the armature; said auxiliary tension member as related to the said diaphragm member having relatively large elastic limits and a low inherent rate of vibration; said auxiliary tension member being non-metallic.

3. A telephonic voice-current repeating instrument, comprising an initially magnetized receiving magnet and its circuit connections; a transmitting microphone and its circuit connections, embodying a stationary rear electrode, an opposed electrode in the form of a single. peripherally-clamped, nonmagnetic, diaphragmatic, composite electrode-diaphragm structure, electrically related to said stationary rear electrode, with the central axis of vibratory movement of said diaphragm-electrode structure substantially coincident with the central line of pull of said magnet; and a rigid block armature in the field of said magnet, rigidly and centrally attached to said diaphragm structure; together With an auxiliary vibration-controlling member for the microphone, in the form of a rectilinearly extensible member, disposed along the central axis of vibration of the microphone diaphragm, extended by means of an attachment to an abutment and to the associated armature and vibratory electrode, and opposing the magnetic pull on the armature; said auxiliary tension member, as related to the said diaphragm member, having relatively'large elastic limits and a low inherent rate of vibration; said auxiliary tension member being further in the form of a stretched rubber strip.

4. A telephonic voice-current repeating instrument, comprising an initially magnetized receiving magnet and its circuit connections; a transmittitng microphone and its circuit connections, embodying a stationary rear electrode, an opposed electrode in the form of a single, peripherallycla1nped non-magnetic diaphragmatic, composite electrode-diaphragm structure, electrically related to said stationary rear electrode, with the central axis of vibratory movement of said diaphragin-electrode structure substantially coincident with the central line of pull of said magnet; and a rigid block armature in the field of said magnet, rigidly and centrally attached to said diaphragm structure; together with an auxiliary vibration-controlling member for the microphone, in the form of a rectilinearly extensible member, disposed along the central axis of vibration of the microphone diaphragm, ex tended by means of an attachment to an abutment and to the associated armature and vibratory electrode, and opposing the magnetic pull on the armature; said auxiliary tension member, as related to the said diaphragm member, having relatively large elastic limits and a low inherent rate of vibration; said auxiliary tension member having means to damp the vibration across its axis of extension.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

CHARLES D. LANNING.

Vitnesses THOMAS B. Boo'rn, ROBERT H. KAMMLER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.

Images