US2432424A

US2432424A - Electromagnetic sound translating device

Info

Publication number: US2432424A
Application number: US550418A
Authority: US
Inventors: John J Hyland; William J Muldoon
Original assignee: CONTROL INSTR CO Inc
Current assignee: CONTROL INSTR CO Inc; CONTROL INSTRUMENT COMPANY Inc
Priority date: 1944-08-21
Filing date: 1944-08-21
Publication date: 1947-12-09
Anticipated expiration: 1964-12-09

Description

1947- J. J. HYLAND ET AL 2,432,424

ELECTROMAGNETIC scum) TRANSLATING DEVICE Filed Aug 21, 1944 Fig 2 INVENTORSV JOf/NJ HYl/JND WILL/AM a. MULDOON Patented Dec. 9, 1947 UNITED STATES PATENT OFFlCE ELECTROMAGNETIC SOUND TRAN SLATING DEVICE Application August 21, 1944, Serial No. 550,418

12 Claims. 1

This invention relates to improvements in sound translating equipment and has particular reference to a telephone unit of the sound powered' type.

Known devices of this character usually comprise a field structure consisting of one or more permanent magnets with which pole pieces are associated and arranged so that their pole tips of opposite polarity are opposed to each other. Said opposed pole tips have their faces in spaced apart relation to receive therebetween opposite end portions of a vibratory armature forming a part of' the motor assembly, and pivotally mounted intermediate its ends in a supporting struc ture about which the voice coil of said assembly is wound in electromagnetic association with said aramature. One end of said armature is connected to a diaphragm responsive to sound waves from an external source in the case of a transmitter, or responsive to mechanical impulses in the case of a receiver, said impulses being generated by the vibration of said armature. Heretofore, in the manufacture of such devices, difiiculties have been encountered in making the same of sufiiciently rugged construction to withstand shocks and yet have a sensitivity which will adequately transmit voice currents and be of a weight and size which will render the instrument practical for universal use in telephone work. Among these difiiculties are the structural formation and arrangement of the parts which increase the size and weight of the instrument, the inability to secure rigid maintenance of the coil assembly, including the armature, in fixed relation to the pole pieces, and the inadequate protection of the armature against the effects of gun or other high pressure blast waves.

The present invention is designed to overcome the above mentioned difiiculties by the production of an improved device of practical, rugged and efiicient construction which will hav the advantages of simplicity and ease of assembly, lightness of Weight, reduction of size particularly with respect to its over-all height, and capable of withstanding extreme shocks without displacement of parts.

In carrying out the above objects, a structure is provided wherein the pole pieces are so constructed and arranged that the same will form th sole support for the elements constituting the motor assembly, and combine to provide a recess for the reception of the voice coil and its armature so that the outer faces of the pole pieces will be substantially in the same planes as the outer opposed surfaces of said coil, thereby materially reducing the over-all height of the unit. In the coil assembly, a simple and positive means is provided for accurately locating 'the armature with respect to the pole tips and for locking said elements together in such manner that lateral displacement of the armature relative to the pole pieces will be avoided, even under the severest shock tests. Further, it is proposed to protect the armatur from the effects of positive blast waves by mounting a stop memher on the upper pole piece in association with the adjacent end of the armature shaft.

The inventive idea involved is capable of receiving a variety of mechanical expressions, some of which are shown in the accompanying drawing; but it is to be expressly understood that said drawing is employed merely to facilitate the description of the invention as a whole and not to define the limits thereof, reference being had to the appended claims for this purpose.

In the drawing;

Fig. 1 is a plan view of a telephone unit constructed in accordance with the invention.

Fig. 2 is a transverse section on the line 2-2 of Fig. 1.

Fig. 3 is a similar section on the line 3-3 of Fig. 1.

Fig. 4 is a perspective View of the lower pole. piece forming a part of the motor assembly.

Fig. 5 is a similar View of the upper pole piece.

Fig. 6 is an exploded perspective of the armature and its support.

Fig. '7 is a perspective view of one of the permanent magnets.

Fig. 8 is an enlarged section of a detail taken through a portion of the armature support, and

Fig. 9 is a transverse section through a modified form of diaphragm assembly.

In its preferred form, the motor assembly of the device comprises, generally, a magnet structure consisting of two permanent magnets Ill arranged at opposite ends of a substantially rectangular voice coil Ii, it being apparent and within the scope of the invention that said magnets may be combined in a unitary structure, if desired. Extending through said coil is the armature l2 supported for vibratory movements by two elements in the form of parallel bars [3 of nonmagnetic material. Said bars are pro vided with recesses i l in the inner opposed faces thereof adapted to receive and have secured therein, by any suitable means such as solder introduced into openings i i in said bars, the extensions i5 projecting. from intermediate points of the side edges of the armature l2 and in a plane therewith, this manner of supporting the armature being well known in the art. An ear I6 is formed at one end of the armature for connection to the shaft ll thereof. The armature and its supporting bars are insertable through and adapted to be secured in the opening of the coil H, as will later appear. As customary, the ends of the armature project beyond adjacent ends of the coil so as to be in operative association with lower and upper magnetic pole pieces 18 and [9 which, in the present instance, are of novel construction and arrangement, as will appear in the course of the description.

In order to overcome the possibility of a short circuit around each end of the armature l2 and through the bars i3 and pole pieces 18 and [9, said bars, which may be of brass, are chemically treated to provide them with nonconducting surfaces. Such treatment may consist in the application of a coating of zinc carbonate or copper oxide to the surfaces of said bars.

The motor assembly thus briefly described is mounted on the perforated cover plate 20 and attached thereto by screws 2| which also secure the usual diaphragm 22 in position. At its center, said diaphragm is suitably connected to the lower end of the armature shaft l1 so that the diaphragm and armature will vibrate in unison. Provision for electrical connections to the coil may be in the form of an insulated strip 23 secured to the upper surface of the pole piece I8 and carrying terminals 24 to which are attached the conductors 25 connected to said coil. A gasket 23 which may be of insulating material is secured to the perforated plate 20 and forms a seat for a cover (not shown) of the unit.

The lower pole piece 3 is in the form of a circular plate equal in size to the interior diameter of the cover plate 20 and, in accordance with one of the features of the present invention, said pole piece provides the base for the entire motor assembly and combines directly with the upper pole piece [9 in rigidly and compactly securing together all parts of the motor assembly. Said pole piece [8 is provided therein with an opening 27 which forms an air space adjacent to diaphragm 22, thus providing more suitable acoustic impedance by exposure of a portion of said diaphragm. An extension 28 of said opening accommodates the armature shaft H. is further provided with a second opening 29 from opposed edges of which there extends laterally the two complementary pole tips 30 which are thus disposed within and spaced from the marginal edge of the plate, as distinguished from known constructions wherein said tips project from edges or ends of the pole piece. Each tip 30 is reduced along its face portion 3! to provide shoulders 32 at the ends thereof, and said shoulders of at least one of said tips are formed with recesses 33 therein for a purpose which will presently appear.

The upper pole piece I9 is of substantially oval formation and has therein an opening 34 similar to the opening 29 in the piece l8. Laterally projecting from opposed edges of said opening 34 are the pole tips 35, the faces 36 of which are provided at their ends with shoulders 31 similar to the shoulders 32 of the tips 39. Thus the tips are also disposed within the marginal edge of the pole piece i9.

When the pole pieces 18 and I9 are assembled, the pole tips thereof are directed oward each other in opposed relation and constitute sets of opposed polarity with their faces spaced apart Said pole piece all) to receive therebetween the end portions of the armature I 2, Thus arranged, the

shoulders

32, 3? of the two pole pieces are in such aligned relation that they will receive and engage the ex tremities of the parallel armature-supporting bars 13 on opposite sides of the latter so as to aid in the maintenance of the armature and its support in proper position. It is highly important that, after assembly, the pole pieces and the armature and its support be accurately located and rigidly held against relative lateral shifting such as might occur under severe shocks and, to this end, the invention provides a simple and effective means in the form of locking pins 38 projecting from the bars l3 adjacent the ends thereof and extending into the recesses 33 in the shoulders 32 of the pole faces 3|. Only two of said pins 38 and their corresponding recesses are shown, but it will of course be understood that a pin and recess for each of the shoulders of both tips of the same pole piece may be provided, if desired or found necessary. When the supporting bars [3 are thus interengaged with the pole piece l8, any relative lateral movements between the parts will be eliminated and the same will be rigidly held together by the clamping action of the

shoulders

32, 31, against the bars 13, said clamping action being effected in a manner to presently appear.

The openings 29, 34 in the pole pieces and the pole tips thereof, combine with the inner walls of the magnets in to form a recess for the reception of the coil H and, when in position therein, the inner and outer surfaces of said coil will lie substantially in the planes of the outer faces of the lower and upper pole pieces, respectively. This arrangement contributes materially to a reduction in the over-all height of the unit and enhances the compactness of the structure without detracting from its mechanical strength or acoustic eihciency. Further, the provision of the space formed by said recess permits of an increase in the height of the coil l l which may be at least equal to the combined thickness of the plates from which the pole pieces I8 and I9 are formed.

After the parts have been assembled as described, they are secured together by means of screws 39 which extend through the end portions of the upper pole piece I9 and into threaded engagement with the lower pole piece 18, the shanks of said screws projecting through slots 40 formed in the magnets l0. Tightening of said screws will draw the pole pieces together into clamping engagement with the flux faces of the magnets it, and, at the same time securely clamp the

shoulders

32, 31 of the pole tips against the ends of the supporting bars l3.

Provision is also made for limiting movement of the shaft [1 under the influence of positive blast waves, this being accomplished by the simple and effective expedient of mounting a stop member in the form of a set screw 4| in the upper pole piece IS in direct alignment with and in space relation to said shaft, where it is positioned for easy access when it is desired to adjust the screw to vary the gap between it and the adjacent end of said shaft.

In Fig. 9, a different form of diaphragm assembly is disclosed, wherein the perforated cover plate 42 is centrally depressed to accommodate the diaphragm 22, and has its marginal edge 43 spun around the periphery of the lower pole piece I8.

What is claimed is:

l. A telephone unit comprising, in combination, a permanent magnet structure, an assembly associated therewith and including a coil and an armature, pole pieces each having tips extending laterally therefrom at points inwardly of the 7 margin thereof and in opposed relation to the tips of the other pole piece, said tips combining to form a recess for receiving said coil with the outer faces of said pole pieces lying substantially in the planes of outer opposed surfaces of said coil, and means fastening said pole pieces, coil and magnet structure in assembled relation.

2. A telephone unit comprising, in combination, a permanent magnet structure, an assembly associated therewith and including a coil, an armature, supporting elements for the latter constituting the core for said coil, pole pieces having tips extending laterally therefrom and combining to form a recess for receiving said coil, said tips having portions of their faces engaging said supporting elements, means connecting said pole pieces for clamping said portions of said pole faces against said supporting elements, and means interengaging said supporting elements and pole tips for preventing relative lateral shifting between said parts both linearly and transversely of the armature.

3. A telephone unit comprising, in combination, a permanent magnet structure, an assembly associated therewith and including a coil, an armature, supporting elements for the latter constituting the core for said coil, locking pins projecting from said supporting elements, pole pieces having tips extending laterally therefrom and combining to form a recess for receiving said coil,

said tips having portions of their faces engaging said supporting elements and being provided in said portions with recesses for receiving said locking pins, and means connecting said pole pieces for clamping said portions of said pole faces against said supporting elements.

4. A telephone unit comprising, in combination, a permanent magnet structure, an assembly associated therewith and including a coil, an armature and two bars forming a support for said armature and constituting the core for said coil, locking pins projecting from said bars, pole pieces having tips extending laterally therefrom and combining to form a recess for receiving said coil, said tips being formed in their faces with shoulders for receiving said bars and having recesses in said shoulders into which said locking pins project, and means connecting said pole pieces for clamping said shoulders against said bars.

5. A telephone unit comprising, in combination, a motor assembly including a permanent magnet, a coil and its armature, a support for said armature, pole pieces associated with said elements, and locking means between said support and one of said pole pieces for preventing relative lateral displacement of said parts in different angular directions.

6. A telephone unit comprising, in combination, a motor assembly including a permanent magnet, a coil and its armature, a support for said armature, and pole pieces associated with said elements, one of said pole pieces constituting the supporting base for said assembly and having tips extending laterally therefrom inwardly of the marginal edge thereof, securing elements clamping said pole pieces against said magnet and said armature support, and locking pins on said support extending into one of said pole pieces for preventing relative lateral displacement of said parts.

7. A telephone unit comprising, in combination, a motor assembly including a permanent magnet, a coil and an armature associated with said magnet, a support for said armature, a pole piece associated with said support, and means to prevent lateral displacement between said support and pole piece, said means including pins projecting from one into the other of the latter two elements.

8. A telephone unit comprising, in combination, a motor assembly including a permanent magnet, a coil and an armature associated with said magnet, a support for said armature, a pole piece associated with said support, one of the last two named elements having recesses therein for receiving portions of the other element, and means to lock said support and pole piece against relative lateral displacement, said means including pins projecting from one of the last named elements into the other.

9. A telephone unit comprising, in combination, a motor assembly including a permanent magnet, a coil and an armature, and pole pieces associated with said armature, both said pieces comprising plates provided with openings opposed edges of which are bent laterally to form pole tips between which said armature extends, and the plate of one of said pole pieces constituting the supporting base for said motor assembly,

10. A telephone unit comprising, in combination, two pole pieces each having tips projecting laterally therefrom and toward the tips of the other pole pieces and combining to form a space therebetween which extends through said pole pieces, a coil mounted in said space, and an armature mounted between the tips of said pole pieces and extending through said coil.

11.A telephone unit comprising, in combination, two opposed pole pieces each having tips projecting laterally therefrom and combining to form a space therebetween which extends through said pole pieces, a coil mounted in said space and being of a height greater than the distance between the inner opposed surfaces of said pole pieces, and an armature mounted between the tips of said pole pieces.

12. A telephone unit comprising, in combina tion, an armature support, pole pieces arranged on opposite sides of said support and each having tips projecting laterally therefrom and combining to form a space therebetween which extends through said pole pieces, a coil mounted in said space, and a balanced armature carried by said support and arranged between the tips of said pole pieces.

JOHN J. HYLAND. WILLIAM J. MULDOON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,562,252 Pihl Nov. 17, 1925 1,671,105 Farrand et a1 May 29, 1928 1,830,160 French et al Nov. 3, 1931 1,870,446 Foley Aug. 9, 1932 1,871,739 Ringel Aug. 16, 1932 2,245,039 Lilja June 15, 1941 2,343,859 Baldwin Mar. 14, 1944 2,391,627 Howell Dec. 25, 1945