US2128385A - Telephone apparatus - Google Patents

Description

Aug. 30, 1938. F. G. TROISI TELEPHONE APPARATUS Filed Aug. 29, 1955 2 Sheets-Sheet l Patented Aug. 30, 1938 UNITED. STATES P TsNrorl-lcs F... ..$Z." a. Application Aunut 29, 1935, Serial No. 38.408

The present invention relates to a telephone instrument intendedto function in a system as transmitter or receiver, independently of external current sources, and constitutes a continuation in part of my application Serial Number 713,023

filed on February 26, 1934.

Due to inherent defects and general inefllciency, instruments of the so called batteryless type heretofore constructed, have failed to meet with commercial success. In most cases the diaphragms oi such instruments have been strained beyond desirable limits in an attempt to obtain maximum amplitudes of vibration and a mini mum weight of the moving system. In attempts to balance the mechanical system, balance of the magnetic circuit has been overlooked with a resulting imperfection oi sound transmission.

Units conforming to the present construction find application for any installations wherein local telephone systems are used, such as for ships. apartment houses, hotels, oifices, mines, factories, etc., as well-as for submarine salvage as disclosed in the parent application already referred to.

In use as a transmitter, the unit of the present invention derives its actuating current from the sound vibrations impressed upon the diaphragm, obviating the need for batteries or other external current sources. As a receiver, the unit converts the incoming electrical currents to sound waves which are reproduced by the diaphragm. While especially intended for use without external current sources, the interposition of a battery or other current source in the circuit is also contemplated.

Faithful reproduction is obtained throughout the audio frequency range with units of the pres-= ent construction, by virtue of the proportions oi the various masses and arrangements resorted to. Undue damping is avoided, and injury to the parts is prevented.

The armature oi? the electromagnetic circuit is supported in a truly balanced condition, and measures are taken to preserve a balance of the magnetic circuit as a whole. v Sound vibrations impressed upon the diaphragm of transmitter or receiver alike, represent more nearly the mean values, whereby distortion is overcome and the diaphragm is subjected to smaller strains than in known structures.

It is with the object of overcoming the faults of and irictionally held thereby.

prior constructions and of attaining the ends,

already outlined, that the present invention is proposed, the details of which will be understood from the following description in conjunction with the accompanying drawings,

Fig. 1 is a partially exploded view of the telephone unit;

Fig. 2 is a detail of portions oi the magnetic system, partially broken away.

Fig. is a sectional elevation taken along line 3-3 of Fig. 1 with the parts in assembled relation;

Fig. 4 is a portion of the section along line H oi'Flg. 1 with the parts assembled;

Fig. 5 is a plan view of the diaphragm;

Fla. 6 is a plan view of the partially assembled unit; and J Fig. 'i' is an. elevation showing one manner in which a pair oithe units may be combined as a set.

A diaphragm it is sandwiched between a spacing ring i Land an annular boss I2 which is integral with and protrudes irom a pertorated cover plate It, whereby an. air chamber is defined between the diaphragm and cover plate. The spacing ring it has a bearing upon a plate it which serves as a support for the various elements. The base plate and cover plate are provided with registering openings and it respectively, for the reception oi assembly screws. Another set 01' openings provided in the cover plate are intended to receive screws for attachment to ahousing, not shown, for enclosing the working parts in watertight condition. a

Secured to the base plate it by-bolts I1, is the assembly for effecting the induced current: in response to the voice or other sound frequencies impressed upon the diaphragm. This assembly comprises a permanent horseshoe magnet i8, pole pieces IS, an armature 20, an armature housing 2 I, a winding it properly insulated fromthe metallic structure, and means for holding the various elements in assembled relation and properly spaced. A pinzt couples the diaphragm assem-- bly to the armature. to which elements its rew spective ends are positively connected, though ad- .justably, by solder or the like.

The bolts i'i have their heads countersunk in the base plate, their shanks extending through thesarnewith a forced fit in order to maintain them'in rigid, spaced relation. The spacing of these bolts is such, that the ends of the horseshoe magnet, it are nicely received therebetweeh Counterboredopenings formed near the opposite ends oi the magnet, receive the screws 24 which threadediy engage the pole-pieces it to fasten the same to thepoles of the magnet. Each of the pole-pieces is preferably termed from a flat sheet of magnetic material, which is out to a substantially T- u shape, the horizontal bar of the T tending to converge at its extremities by virtue of a slight taper on its lower edge. In assembled relation, these pole-pieces each have a vertical portion contiguous to and coextensive with the poles of the horseshoe magnet. One end of each of these vertical portions (in Fig. 2' the upper end oi the left hand pole-piece and the lower end of the right hand pole-piecel joins a horizontally extending portion which is substantially coplanar with one of the planes of the horseshoe magnet. The tips of the pole-pieces are formed by folding inwardly towards the axial plane of the permanent magnet, a pair of wings which constituted the horizontal bar of the original T. These wings or tips of the respective pole-pieces extcnu towards one another, but are maintained in a pre determined spaced relation by .a series of lugs t5 extending from the armature housing.

A light weight armature 20 of magnetic material, and substantially rectangular in plan, has a short perforated integral lug 25 extending centrally from one side thereof. Parallel to the side bearing the lug 26, on a line passing through the center of gravity of the armature, a pair of open ings are formed, symmetrical with respect to said center of gravity, through which the ends of a supporting pin 21 are passed. The pin is preferably a length of resilient wire having its ends bent at to their base, forming a pair of parallel arms. The base of the pin is permanently attached to the armature, as by soldering or the likepindlcated at 2B.

The ends of the pin 21 are received in openings formed in the upper surface of a one-piece armature housing 2| which is of rigid, light nonmag netic materialfpreterably metal. The armature is centered in its housing, whereupon the pin ends are riveted and aflixed to the housing by soldering or the like. The housing comprises a top surface, a pair of side Walls perpendicular thereto, opposed base portions spaced from one another and parallel to the top surface, and carefully calibrated lugs 25 projecting from both ends of both side walls, making four in all. The upper and lower edges of all of these lugs 25 lie in two parallel planes, for the purpose of spacing the pole pieces IS. The base of the housing, being discontinuous, prevents to a large extent, the effects of eddy currents.

Bridging the gap between the base portions of the armature housing, there is provided an insulating block 29, which in conjunction with its insulating wrapping 30, spaces the spool flanges 3| of insulating material, which are provided with elongated slots for the reception of the armature housing. Thus, except for its lugs 25, the armature housing serves as a core for the magnet winding 22 which is formed upon the wrapping 30 and between the flanges 3|. These elements are held in assembled relation by bending the four lugs 25 outwardly along their line of junction with the housing proper. After the predetermined number of turns of suitable guage wire have been applied on the spool, an insulating covering 32 is wrapped about the coil so formed.

A clamping bar 33 of non-magnetic material is provided with openings for the reception of the threaded ends of the bolts H, for clamping the assembly to the base plate upon application of the nuts 34. The bar is provided with a pair of locating pins 35, preferably pressed from the material '01 the bar itself, which pins are received in a pair of cooperating openings in the upper I surface of the magnet. Also, the bar preferably bowed downwardly at its central pi rtlon so as to resiliently bear against the horizontal portion of the upper pole-piece 3B. The lower polepiece is also given a definite bearing surface against the base plate by designing the latter in the manner shown in Fig. 6. The central aperture of the base plate is formed of two concentric semi-circles of different radii. Thus the smaller semi-circle 37! leaves sufiicient material to suppm" "t the pole-piece without unduly damping the di While the larger semi-circle it provides a sufficiently large passage r air within the instrument so as not to interfere with its sensitivity and operation.

As shown in Fig. 4, the armature preferably terminated in the planes of the poleiece surfaces so as to be cut by substant flue: emanating therefrom. To p age through fatigue, the armature lug as short as possible, and to allow for ie solder or the like applied thereto for holding the pin .25], the rear surfaces of the pole-pieces are provided with grooves 40. A further and more important function of these grooves, is the balance of the magnetic system which is achieved thereby. The projecting lug 25 tends to decrease the reluctance of the gap at the rear of the polepieces, which factor is compensated by reducing the area of the pole faces at this point. Consequently, the torque applied at the opposite sides .of the fulcrum provided by the pin 21 will be equalized and likelihood of distortion dimh'lished.

After the diaphragm i0 is clamped into position, the pin 23 is inserted'through the opening in the lug 26, and with the armature assigned to its final neutral position with respect to the opposed pole tips, the pin is fixed to the lug. Should the diaphragm subsequently become bent, or should there be need of adjustment for another reason, the pin may be readjusted with respect to the armature lug and a new joint formed.

The ends of the winding 22 are brought out to a suitable terminal block 41, from which they are connected to their respective conductors for completing a circuit with one or more similar units.

The diaphragm I0 is preferably a thin disk of resilient flexible material, such as duralumin, highly responsive to voice frequencies, which in the form shown, has been impressed with a series of concentric corrugations, the spacing and depth of which in general, increase as their diameters decrease.

Whereas it is usual practice in devices of this type to solder or otherwise connect the center of the diaphragm directly to the pin which transmits the movements to or from the armature, more reliable and generally better reproduction has been obtained in this construction by transmitting movements between diaphragm proper and the pin through an intermediate, substantially rigid member which is supported at a plurallty of points on the diaphragm. To prevent undue damping of the diaphragm, this member is attached at the peak of a corrugation, being otherwise out of contact with the diaphragm.

This connecting member 42 which is preferably of light yet rigid construction, has a body portion of substantial cone shape, terminating at its base in a rigldifying bead 43, extending from which, there are a plurality of short stiff lugs 44 which are perforated for the reception Ill) of rivets 45 for attachment to the diaphragm 76 a waterproof and plastic material such as a wax is applied over the solder.

As shown, three lugs connect the member 42 with the diaphragm, this number having been chosen as a-balance between light weight .and rigidity, both of which factors are important. Whether the movements are transmitted from the diaphragm to the armature while the unit serves as a transmitter, or from the armature to the diaphragm when in use as a receiver, a more nearly perfect reproduction is effected than with a. pinconnected at a single point to the center of the diaphragm. The number of such lugs may be varied without departing from the spirit of the invention.

The air chamber between the diaphragm and the diaphragm cover is designed with respect to the moving system, that is, the diaphragm, its pin and the armature, so that when a. plurality of the units are connected in a circuit, the circult will be substantially uniformly responsive to frequencies throughout the audible range. The resonance of a unit used as a receiver will be difierent than when it is used as a transmitter, due to a change of its effective air cham-- her, and the number of different resonant frequencies of the system will be increased, tending to render uniform the output of the system over the entire audible range.

As appears inFig. 3, the length of the pole tips is necessarily slightly greater than the length of the armature housing for the lugs to perform their function of spacing these pole tips uniformly.

These telephone units operate as transmitteror. receiver interchangeably. and due to their construction, operate emciently under the high pressure conditions to which they are frequently subjected as in under water salvage operations when used as a transmitter, the vibrations of the diaphragm set up by the voice, are imparted to the balanced armature through the pin a. The movements of the armature in the field of the permanent magnet, vary the reluctance of the magnetic circuits with a frequency proportional to that of the sound waves producing these movements. Accordingly, proportional currents will be induced in the winding, which currents will be carried to similar units serving for the instant as receivers. When current flows in the receiver winding, magnetic flux will be produced to oppou or reinforce that of the permanent units especially adaptsthem to use in connection with submarine salvage apparatus, they have been highly successful in other uses and their application is not to be restricted beyond the scope of the appended claims.

I claim:

1. A telephone unit comprising a permanent magnet carrying a pair of detachable pole pieces, an electromagnet embraced by said pole pieces, said electromagnet comprising a spool having separate flanges and a discontinuous one-piece sheet metal armature housing having elements holding said spool in assembled relation and projecting between said pole-pieces and in contact therewith for limiting the positions of the latter.

2. A telephone unit comprising a permanent magnet carrying a pair of pole-pieces, an electromagnet embraced by said pole-pieces, said electromagnet comprising an armature and a. one-piece sheet metal housing therefor, a spool composed of a plurality of elements formed about said housing, said housing carrying lugs engaging and holding the spool in assembled relation and contacting said pole-pieces for spacing the latter.

3. A telephone unit comprising a base plate carrying a pair of spaced bolts, a horseshoe magnet carried by said base plate having its legs in frictional engagement with said bolts, pole-pieces carried by said magnet having surfaces coplanar with those of the magnet and a clamping bar receiving said bolts ensasins coplanar surfaces of said magnet and-said pole-pieces for. clamping the same to said base plate. v

4. A, telephone unit comprising a horseshoe magnet having a pair of oppositely directed polepieces rigidly attached thereto, said pole-pieces having surfaces coplanar with those of the magnet, a clamping bar engaging the upper surfaces of a pole-piece and the magnet and having positioning pins received by apertures in the magnet,

a base plate engasing the lower surfaces of a HORENTmO G. 'I'ROISI.

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