US1550794A - Magneto telephone - Google Patents

Description

Aug.2s,192s. 1,550,194

R. D. FAY

MAGNET() TELEPHONE Filed April 13'. 1922 Patented Aug. 25, 1925.

UNITED STATES PATENT OFFICE.

RICHARD D. FAY, OF N AHANT, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO HAMMOND V. HAYES, TRUSTEE, OF BOSTON, MASSACHUSETTS.

MAGNETO TELEPHONE.

Application led April 13, 1922. Serial No. 552,325.

T0 all whom t may concern.'

Be it known that I, RICHARD I). FAY, of Nahant, in the county of Essex and State of Massachusetts, a citizen of the United States, have invented a new and useful Improvement in Magneto Telephones, of which the following is a specication.

I will take the case of an electro-magnetic telephone as the simplest illustration of the application of my invention to a practical and useful p-urpose. It is well known that a telephone when used as a receiver must transform the alternating currents which are made to pass through the coil or coils of its electro-magnet into a to-and-fro movement of a member which will produce the compressional waves in air which are called sound. The best receiver is one which will make this transformation from electrical waves into air waves with the least possible loss in energy and will at the same time create sound waves as nearly as possible similaiin form and relative intensity as the electrical waves which actuate it. Similarly when the telephone is used as a transmitter for transforming air waves into electrical waves, the best form is that in which there is the least loss of energy in the transformation and in which there is the least distortion in electrical wave form from that of the actuating air wave form.

Or, if the case of a quick-acting relay is considered, the design must be such as will offer the least possible loss or deformation of the incoming electrical wave and at the same time create a motion of the moving part as quickly as possible and with the least possible loss of energy.

The well known form of Bell receiver does not meet the requirements. outlined above, both on account of its high effective resistance and from the fact that there are large losses in the magnetic circuit arising from the necessity of having a thin diaphragm, forming a portion of the magnetic circuit, and considerable separation between the pole pieces and the diaphragm. I am aware that attempts have been made to overcome these difficulties by the elimination of the diaphragm as a portion of the magnetic circuit as has been done by supporting from the diaphragm a light coil or a tube of conducting material, said coils or tubes moving in a powerful magnetic field. The weight of these moving parts and the large air gap required in the magnetic field has resulted in little or no improvement in.`

the sensitiveness of such devices when used as telephone receivers, although instruments of this type have one important advantage m that the amplitude of the moving parts is restricted only by the flexibility of the diaphragm to which they are attached.` I am aware that another type of receiverl has been devised in which an armature, piv-j cted or hinged between the two poles of a` magnet or electro-magnet, is used, such argreater amplitude of motion of the soundff.I

energy.

My invention consists in an electro-magnet in which the armature is normally substantially under no strains such as are imposed by springs or similar means and is free to move in a substantially uniform field with unrestricted amplitude as far as the magnet is concerned.

The armature of my electro-magnet, when no alternating current is acting upon it, is so balanced that there is no resultant longitudinal pull upon it.

In the drawings accompanying the present specification my invention is shown in its preferred form.

Figure 1 s a front elevation of my electromagnet.

Fig. 2 is a section on line Qf-EZ of Fig. 1.

Fig. 2L is a modification.

Fig. 3 shows the armature of my electromagnet as blanked out.

Fig. I is a sectional view of a casing enclosing my electro-magnet when used in a magneto telephone.

Fig. 5 is a plan of my electro-magnet.

1 is a spool of insulated wire for carrying the alternating currents used when the electro-magnet is actuated, its leads l(not shown) CII being connected with a suitable source of alternating current. 2 and 3 are pole pieces which pass, respectively, over and under the spool (see Fig. 2), being connected to the horse-shoe magnet M by bars 2l and 8l. (S is the armature which is a thin plate ot iron or high permeability which passes through the central opening in said spool l. This armature is punched or blanlied as shown in Fig. 3 and then bent into the torni shown in F ig. -1. rEhe metal removed inales a reetangular hole at 7, leaving two nai-ron` strips at 8 and 9,1 and when the armature is bent into the form shown in Q, it the end ll is held lirmly and pressure applied at the end l0, the strips will bend easily thus form practically a spring hinge for the armature. rllhus the ond l0 has D dom oit movement while there is relatively small movement ot the armature at points where the strips 8 and i) the main body of the armature 6. The bent end ll of the armature is held rigidly upon one et the pole pieces by 'four screws l2, 13, and l5. Screw l2 is tapped into the pole piece and screws 18, and l5 are tapped into the part ll, their ends resting` against the pole piece.

The pole pieces Q ant 3 are extensions ot magnet M, and as shown are shaped to substantia-lly surround the coil and form a row slit in which the armature in u "'ibratd the edges 4l and 5 being chain'rered to di reet the magnetic linx onto the armature.

An important feature orn my invention lies in the relation which is made to exist between the pole pieces and the armature. To illustrate th's relation, Fig. 2 is presented which is a oross section at Qr-Q of li. See, also, lEig. 2l which shows the armature blank arranged in relation to one ot the pole pieces. lt will be seen that armature 6 can be brought into the closest proximity to the surfaces and of the pole pieces and, as the pole pieces are slotted as at a; to allow the projection l0 move freely, the armature can travel to points within the Chamber enclosed by the pole pieces, but it is so proportioned with relation to the pole pieces that it will not touch them eren when its movements are. the greate a result of this design the magneti( ill; s between 6 and 2, 3, et and are subst and as a consequence there is no lonsri strain exerted ipon (l by t pole faces. Moreover, the through the armature ar practically nnmagnetized longitudinally and as a consequence the lai i st ssible i of lines of 'force will be induced in it by the alternating currents when L assing through tb. e

coil l. lt the alternating current at a Y. Ten instant ot tune makes the armature horth at its ree end, it will be polarized South at the end at which 1t 1s pivoted.

Theoretically strips 8 and 9' should be of non-:nagnetie n'iaterialv` bnt for mechanical reasons l bave preferred to use the same ma- 'for these strips as that used in the "are and to eli. `inate losses by reducthe e e sections et the stri*L to a miniconsistent with the requisite mechani- TKT i i ln i the gen-ral arrangement of my bloemmagnet as :rpg-lied to a telephone re- I is chown. Y i this orar-:ing 16 is a A .'YX! AL Stlll.

2C has one enc secured to l`he other end et the rod is attached and Thus nre are imparted be a permanent or elecdesired and other changes nfnetion shown in the drawbe made without departing fron "ter oi" my claims renten is particularly adapted to nets in such forms as are used ting relays. 'found that a very etlicient way ot ing the armature is that shown in j Q5 where as shown at 32 a piece o' ,stic material such as sott rubber is placed between the armature and the pole piece and a second like pi ce ot material is placed outside the armature. is a metal Qiece or Yasher. il screw 2 A asses through this washer and tao members 3; as well as through the armature and holds the armature to the pole piece.

lVhat claim as my invention is:

fr device of the lind described Compris! ing a lield magnet having pole pieces located to ,torni two short air gaps in the magnetic eii mit, ni s ttor supporting an armature attaened at one end to said l support eans whereby its other end may swing k A-- 7 sait pole pieces being located on opposite side armature be" f 3. ln a device of the kind described, magnet the poles of which are located to form two gaps of different length in the magnetic path, an armature located between said gaps with one end projecting into the longer of said gaps and with the other end overlapping the pole pieces at the shorter gap, said armature being hinged near the projecting end.

4. In a device of the kind described, an electro-magnet responsive to alternating currents, having a normally longitudinally uninagnetized armature pivotally mounted near one end thereof, a field magnet, the other end of said armature being located in close proximity to two pole faces of said field magnet of opposite polarity, said pole faces and said other end of said armature being shaped with relation to each other whereby said armature may be given an amplitude of vibration mechanically unrestrained by said poles.

5. An electro-magnet having an armature hinged nearmoneend, an alternating current coil located to surround kthe free portion of said armature, afield magnet having recessed pole pieces located to partially enclose said coil, the free end of said armature being proportioned to vibrate within the recesses in said pole pieces.

6. A magneto-telephone comprising a diaphragm and means by which it is actuated comprisinga magnet and an armature, said magnet comprising a coil located between the two pole pieces of said magnet, said pole pieces being in close proximity to each other, one end of said armature being attached to one of said pole pieces and the other end thereof lying within the coil and between the surfaces of said pole faces adjacent to the coil.

7. A field magnet, an armature, a mounting therefor engaging one end thereof Whereby the other end of said armature is free to vibrate, a coil surrounding said armature, the poles of said magnet being recessed and said armature being located to vibrate within said recesses.

8. A magneto-telephone comprising a diaphragm and means by which it is actuated comprising a magnet and an armature, said magnet comprising a coil located between the two pole pieces of said magnet, said pole pieces being in close proximity to each other, one end of said armature being attached to one of said pole pieces and the other end thereof lying within the coil and between the surfaces of said pole faces adjacent to the coil, said armature-attracting means comprising a clamp having two pieces of soft elastic material, one located on each side of said end and means for clamping said elastic material and said end to its pole piece.

RICHARD D. FAY.

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