US 2058071 A
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Description (OCR text may contain errors)
Oct. 20, 1936. w ELLMORE I 2,058,071 SPEAKER UNIT Filed July 2, 1954 2 Sheets-Sheet 1' Oct.20, 1936. w. A. ELLMOR E 2,058,071
. r SPEAKER UNIT I Filed July 2, 1934 2 Sheets-Sheet 2 Patented .0... 20, 1-936 v SPEAKER UNIT William A. Ellmore, Wilmette, 1u., assignor to Utah Radio Products Company, Chicago, 111., a
corporation ofv Illinois Application July 2, 1934, Serial No. 733,365
4 Claims. (Cl. 179-119) The invention relates generally to devices for transforming electrical vibrations into sound vibrations and more particularly to a device of the type generally known as a magnetic speaker.
A general object of the invention is to provide a. novel device of this character having an improved arrangement and relationship of parts by which simplicity of manufacture, ease of assembly, and accuracy of adjustment are achieved.
Another object is to provide a device having high operating efficiency.
Another object is to provide a new and improved device wherein the voice coil is disposed in substantially the closest possible relation to the armature which is responsive to: the energizations thereof whereby to obtain maximum efiiciency in operation.-
vibrated, andfor obtaining accurately the precise relationships required in the assembly of the several elements comprising the cone driving mechanism.
Other objects and advantages will become apparent in the following description and from the accompanying drawings, in'which:
Figure 1 is a fragmentary rear view in elevation of a device embodying the features of the invention.
Fig. 2 is an enlarged fragmentary centralsection through the device taken along the line 2-2 of Fig. 1.
Fig. 3 is an enlarged view showing a detail of the cone mounting or supporting member.
Fig.4 is a distended view in perspective of the several elements forming a part of the means by which the armature is supported.
Fig. 5 is a fragmentary sectional view of the cone driving mechanism taken as indicated by the line 55 of Fig. 6, the cone support being omitted for clarity.
Fig. 6 is a sectional view of said mechanism taken along the irregular line 6-6 of Fig. 5.
Fig. '7 is a sectional view of said mechanism taken transversely thereof on the line Fig. 5.
and what may be termed a motor or driving Fig. 8 is a fragmentary perspective view of the armature'and pole piece assembly.
Fig. '9 is an exploded view showing the several elements constituting the adjustable mounting of the armature. While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe, in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling'within the spirit and scope of the invention as expressed in the appended claims.
In devices of the type to whichthis inventionrelates, the speaker unit conventionally embodies a suitably supported sound vibration producing means, generally designated in in the drawings,
means, indicated at l l, by which electrical vibrations are transformed into mechanical vibrations and transmitted to the sound vibration producing means. The desired result is, in the present device, produced by theeifect of a permanent magnetic field upon a movable armature which is variably magnetically energized by varying or alternating electrical currents passing through an associated voice coil, the responsive movements of the armature being suitably transmitted to the dei/ice for producing sound vibrations.
With particular reference to Figs. 2,5 and 6, a preferred. form of driving means ll embodies the following structure and arrangement of parts. A flat base i2, preferably of elongated, somewhat oval shape, .has outstanding from one side thereof integrally formed supports or posts l3 which may be rectangularly arranged as shown. These posts secure what may be termed a pole piece assembly to the base in definitely 40 fixed relationship thereto. The pole piece assembly comprises a pair of spaced-plates M, l5 which support therebetween a pair'oi pole pieces l6,. l6. Each pole piece,'as shown in Figs. 2 and'6, preferably consists of a stack of lamina-.- tions which are substantially .U shaped (see Fig. 2). 0n the outer sides of the legs of each lamination are projecting nibs l'l providing elongated ribs Onthecomplete pole assemblies or pole? pieces which are fashioned for engagement with slots lilprovided in the spaced plates I4, I 5. The slots are so formed as to receive the ribs snugly: whereby precisely and securely to mount tliepole pieces between the supporting plates.
fine a channel which has a central transverse gap and faces along the major dimension of the supporting plates and base. In assembly, one of the supporting plates, in this instance the plate i4, abuts the base l2 and the corners of said plate are cut away to clear the posts l3. The other plate overlies the posts and is apertured to allow screwthreaded extensions ill on the posts to pass therethrough. Nuts 23 threaded onto said extensions rigidly secure the pole piece assembly to the base. If desired other screws 23' through the base and engaging the base abutting plate l4 may be employed finally to secure the parts permanently together.
While the pole pieces l3, l6 may be magnetically energized in any suitable manner to produce a permanent magnetic field therebetween the present embodiment attains this end by means of a pair of permanent. magnets 2| which are U shaped and are of somewhat greater overall dimensions than the base I2. The magnets are disposed in end to end relation with their like poles abutting and with their meeting faces located substantially on the transverse median line of the pole pieces, as shown in Fig. 6. Thus, the pole pieces l6,- Iii have opposite polarity and the magnetic attraction between each magnet and the pole pieces is ample to hold the magnets in place against endwise movement outwardly. The magnets rest against the base i2 at one side and the open face defined by the other side thereof may be suitably closed and the magnets held in place by a cover member 22 (Fig. 5) which is preferably secured by nuts 23 threaded onto the extensions IQ of posts l3.
The structure thus far described comprises the means by which a permanent magnetic field is produced in the present device. Operatively located within this field is an armature having a voice coil closely associated therewith so that the armature will be magnetically energized in accordance with electrical current variations passing through the voice coil. The attraction and repulsion action resulting from such variable magnetization of the armature in the permanent magnetic field causes the armature to move accordingly. As may be seen clearly in Fig. 5, the armature comprises a stack of laminations 24 of rectangular form which are secured together by pins 23 passing therethrough from end to end. The armature is dimensioned substantially to fill the space between the pole pieces but is of slightly less thickness than the width of the space between the pole pieces to provide a relatively small clearance between each side of the armature and the pole piece opposed thereto.
The armature is surrounded by a voice coil, the structure of which preferably comprisesa supporting case 26 of a thin dielectric material formed to provide an outwardly facing channel within which a number of turns of wire 21 are wound. The case 23, as shown in Fig. 6, is centrally open to'fit closely yet loosely about the armature and is dimensioned to fit snugly (see Figs. 2 and 8) within the channel defined by the U-shaped pole pieces l6 and I3. This snug fit positions thjevoice coil against other than longitudinal movement of the coil assembly through the channel. To prevent longitudinal movement, lugs 23 outstandingfromthe voice coil case 23 are provided for engagement with the opposite side faces of at least one of the pole pieces. Thus, the voice coil assembly may be definitely and accurately fixed with respect to the pole pieces.
The armature 24 must be supported in accurately spaced relation between the active faces of the pole pieces. In the present embodiment the means for supporting the armature not only rigidly'secured thereto by the pins 23. The arms I project in this instance through registering apertures 3| in the base l2 and supporting plate l4. Overlying the outer face of each arm 29 and end portion 33 is a plate 32 which is rigidly secured to the assembly by the pins 23 and by rivets 33 or the like. Each of the plates 32 carries a brir' Te-like member 34 in the form of a U-shaped structure having diverging arms and dimen- :ioned to fit over or straddle the voice coil strucure.
The assembly of one of the plates 32 with its bridge member 34 is best shown in Fig. 4 and is relatively important since it provides a simple but exceedingly accurate means for securing these parts together. Thus, the plate 32 has apertures 35 and 33 through which the rivet 33.and pins 23 respectively extend in securing the plate to the armature assembly. The end of the plate opposite that at which the aperture 33 is located has an intermediate end recess 31 providing spaced longitudinally extending nibs 33. One diverging leg ofthe bridge member 34, which leg is designated 33, has notches 43 out in its opposite side faces near the end thereof to receive the nibs 33 when the parts are moved together at right angles to each other. The other diverging leg, designated 4i has a centrally located end projection 42 which is adapted to be received within an aperture 43 appropriately formed-on the plate 32. Thus, when the nibs 33 and notches 43 are engaged and the bridge member forced sideways to position the projection 42 in the aperture 43, a binding engagement between the nibs 33 and the margins of the notches 43 results. The projection 42 may then be secured to the plate 32 in any suitable manner, as by soldering, to complete the assembly. In consequence, the bridge member 34 may be secured to the plate 32 in a very simple manner which nevertheless insures that all necessary accuracy will be obtained.
Each bridge member 34 has a flat base portion designated 44 which contains spaced apertures 43 adapted to receive tongues '43 on a fiat bar 41. A permanent connection between these parts is obtained in anysuitable manner as by soldering. The bars are arranged to extend outwardly from the base 44 at right angles thereto; and to the plate 32, and the parts are arranged so that the longitudinal line of the bars 4! lies substantially thereof has an.outstandingvlug48 acrosswhich the bars. 41: extend: The, lugs: and the I mounting means associated therewith are substantially identical and only one constructionwill-therefore v I be described.
l l The outer. face of a semi-circular recess49 (Figs. land 9) adapted to receive a semi-cylindrical bearing 50. The cen-. ter onJwhich the arcuate surfaces ofthe recess and bearing are formed is substantially the pivotal axis of thearmature. Opposite the arcuate each log 48 is provided with surface on the bearingis a channel 5| dimen sioned snugly to receive the bar 4]. Opposed recesses 52 are provided in the sides of the channel to receive lugs 53 formed on a plate 54 which is arranged to overlie the bar 41 after it has been positioned in the channel. -A binding plate 55 is secured to the lug 48 by screws 56 and the plate extends across the recess 49 in the lug for engagement with the outer face of the plate 54.
With respect to the operation of mounting the armature structure and adjusting the position of the armature relative to the pole pieces, the bar is positioned in the channel 5| between the bearing 50 and the plate 54, the bearing is placed in the recess 49, and the binding plate, by means of the screws 56, is caused to engage the outer face of the plate 54. It will be evident that by tightening or loosening one or the other of the screws-56, a' slight rotational movement of the bearing 50in the recess 49 may be produced and this movement is utilized to adjust the armature to a desired operative position between the opposed faces of the pole pieces. As may be seen in of the cone mounting between theapex and the Figs. 5 and 9, the bearing 50 is somewhat longer than the thickness of the lug 48 to permit adjustment of the position of the bearing and its cooperating plate 54 along the length of the bar 41.-
Since movement of the armature produces a torsional strain in the bars 41, the resistance which is offered to movement by the armature may be adjusted to a proper value by locating the bearing 50 at a proper point along the bar 47,.
It will be evident from the foregoing that the armature may thus be accurately set in its proper operating position with respect to the pole pieces and that the resistance to movement imposed on the armaturemay be easily and accurately adjusted.
The arms 29 which extend outwardly from the armature assembly beyond the base l2 converge. as maybe seen in Fig. 5, and at their outer ends are joined by plates 51. From these plates a short link 58 extends at right angles for connection with theapex of a cone 59 which herein constitutes-the sound vibration producing means Hi. This cone is supported by a generally conventional cone mounting in the form of a stamping 60 to which the marginal edge of the cone is suitably connected as at 6|. The cone mounting is generally conical, has a cup-shaped apex.
and is fashioned to extend about the rear face of the cone. A portion of the mounting near the apex thereof is struck outwardly and offset rear wardly, as at B2, to terminate in a fiat portion 63. Other portions, designated 64, are struck out rim thereof to" provide flat. surfaces which are substantially parallel to the struck-outpart 63.
The base l2 on its outer surface thereof has an upstanding lug 65 intermediate its ends and near one side of the base and has other outstanding lugs 66 spaced longitudinally of the base adja- J cent to the other side thereof. The arrangement 4 of these parts is such that the struck-outpertion 63 is disposed outside of and in abutment with the lug 65, while the struck-out portions 64 are in abutment .with the outer, sides of the lugs mounting from the base or frame of the driving mechanism and the assembly is exceedingly rigid. If desired, an insulated distributor BBfor cooperation with the, lead wires from the voice coil may be secured to the lug 65 by the associated screw 61.
It will be seen from the foregoing that a speaker unit has been provided which embodies an improved arrangement of structurcand a novel aryrangements of parts.
structurally, the various elements which comprise the unit are capable of being produced by simple manufacturing processes. The assembly of the various elements into a complete structure may be easily accomplished g and once the parts have been assembled, the only formed by said magnets with the bases thereof abutting the magnets and crossing the line of engagement between the magnet ends, said pole members being opposed'but spaced from each other and the legs thereof defining a channel extending lengthwise of the magnet assembly, an armature in the space between the pole members, a voice coil assembly located in said channel and encircling said armature with the coil in closely and symmetrically spaced relation thereto throughout, said voice coil assembly having a snug fit in said channel and having means thereon interengaging a pole member to prevent movement thereof longitudinally of said channel, supporting means secured to said armature at each end and straddling said voice coil structure, a frame supporting said magnets and pole pieces, adjustable means for connecting said supporting means with saidframe, a sound vibration producing device, and means for operatively connecting said armature'with said device including arms connected with opposite ends of said armature.
2. In a speaker, the combination of means providing a permanent magnetic field, a stack of laminatlons constituting an armature located in said field and having a voice coil in closely encircling relationship thereto, and means for operatively supporting said armature including a platesecured to each end of the armature and extending beyond the opposite sides thereof, one extending end having alined notches in opposite sides thereof and the other end being substantially centrally apertured, a U-shaped bracket for each plate having diverging side arms and adapted to pass about the voice coil at that part of the assembly, one side arm having nibs fashioned to fit into said alined notches upon insertion in a direction substantially at right angles thereto and to perfect a binding engagement between the parts when the other end is engaged with said plate, said last mentioned end having a part engageable within said aperture for securing the parts together, an outwardly extending arm fixed centrally to each bracket and extending therefrom substantially on the center line of the armature assembly, means connecting with said arms for operatively supporting said armature assembly, and means connected with said brackets and extending substantially at right r angles to said arms for connection with a sound 10 vibration producing device.
3. In a speaker, the combination of means for producing a permanent magnetic field, an armature located in said field and having a voice coil in closely encircling relationship thereto. and means for operatively supporting said armature including a plate secured to 'abut each end of the armature and to extend beyond the opposite sides thereof, one extending end having alined notches in opposite sides thereof, a U-shaped bracket for each plate having diverging side arms and dimensioned to pass about the voice coil at that part of the assembly, one side arm having nibs fashioned to fit into said aline'd notches upon insertion in a direction substantially at right angles thereto and to perfect a binding engagement between the parts when the other end is secured to said plate. and means fixed to each bracket and extending therefrom substantially on the center line of the armature assembly for operatively supporting said armature assembly.
4. In a speaker, the combination of means for producing a fixed magnetic field, a stack of laminations constituting an armature located in said field and havinga voice coil in closely encircling relationship thereto, and means for operatively supporting said armature including a plate secured to the armature abutting each end thereof, a U-shaped bracket for each plate having side arms dimensioned to pass about the voice coil. means for securing said brackets to said plates. means connected with said brackets for operatively supporting said armature, and means connected with said brackets and extending substantially at right angles to said armature for connection with a sound vibration producing de-