US2137780A

US2137780A - Speaker

Info

Publication number: US2137780A
Application number: US75442A
Authority: US
Inventors: Walter J Paredes
Original assignee: ARLAVOX Manufacturing Co
Current assignee: ARLAVOX Manufacturing Co
Priority date: 1936-04-20
Filing date: 1936-04-20
Publication date: 1938-11-22
Anticipated expiration: 1955-11-22

Description

SPEAKER Filed April 2o, 195e 3 Sheets-Sheet l Nov. 22, 1938. w. J. PAREDES SPEAKER 3 Sheets-Sheet Filed April 20, 1936 f'zzyefzzlar: A Eygczf'er Paredes .0 Mo@ my/M1.

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Nov. 2.2, 1938. w. J. PAREDES SPEAKER Filed April 20, 1956 3 Sheets-Sheet 3 Patented Nov. 22, 1938 SPEAKER Walter J. Paredes, Chicago, Ill., assigner to Arlavox Manufacturing Company, a corporation of Illinois Application April 20, 1936, Serial No. I75,442

6 Claims.

'Ihis invention relates to a speaker for radios and the like, and more particularly to a speaker having a permanent field.

One feature of this invention is that it provides V an effective field for the motor means, with a small block of permanently magnetized material; another feature of this invention is that the actuating means for the .armature of the speaker motor comprises a single loop of a relatively 10` heavy strip of metal;`yet another feature of this invention is that the actuating means also forms the vsecondary of the energizing transformer, and acts as a mounting therefor; yet another feature of this invention is that a single straightlever,

15' rigidly mounted on the armature, forms the connecting means between the armature and the diaphragm of the speaker; a further feature of this invention is that the connecting lever is so constructed and arranged that a straight drive from 20` the armature to the diaphragm is effected, permitting compact mounting of the motor means with relation to the rest of the speaker; another feature of this invention is that the motor frame is so constructed and arranged as to readily as- 25 semble the various parts, and to make a single unit of considerable structural strength, easily and compactly mounted on the basket of the speaker; still other features and advantages of this invention will be apparent from the following specifica- 30- tion and the drawings, in whichl Fig. 1 is a top plan view of the speaker; Fig. 2 is a vertical elevation of the speaker from the motor end; Fig. 3 is a fragmentary sectional view along the line 3-3 of Fig. 1; Fig. 4 is a horizontal 35 sectional view along the line 4`4 of Fig.` 2; Fig. 5 `is a vertical sectional View along the line 5-5 of Fig. 1; Fig. 6 is a vertical sectional view along the line 6--6 of Fig. 1; Fig. '7 is a perspective view ofthe eld elements and block of magnetized 40 material; Fig. 8 is a perspective View of the armature and connecting lever; and Fig. 9 is4 an enlarged perspective view of the actuating coil.

The earlier speakers or mechanical-electrical translating devices, used in the radio field for 45 transforming variable currents into audible sound waves, were generally of 'the type wherein 'only one magnetic field was employed and the variable current varied this field to provide greater or less attractive force on a metal diaphragm. More 50 recently, speakers have been almost exclusively of the so-calleddynamic type, wherein one field is provided,` and an armature is placed therein, and a second field is set up in said armature with the variable currents to cause movement thereof.

55 Thismovement is then transferred by some me- Vmately 25%, 15% and '7% of the total.

chanical connecting means to the diaphragm, now generally cone-shaped and of non-metallic material. Such speakers generally have a field developed through the action of coils energized by a relatively heavy direct current, and thus con- 5': siderable drain exists on the power pack or batteries supplying the speaker field. v

More recently, a magnet metal or material, capable of about ten times the coercive force of ordinary magnet steel, and which maintains its 10 magnetization substantially permanently, has been developed. This `material is an iron base alloy, also containing nickel, aluminum and cobalt, which latter named metals form approxi- With this material, permanent magnet elds can be made of sufficient strength to operate properly ln the motor means of a speaker of the preferred type.

While this material, commercially available and not further described here, since it forms no part of this invention, has high coercive force, it is expensive, brittle, and not readily workable by any means except grinding. 'I'he presentv invention uses only a relatively small block of this material, substantially cubical or somewhat rectilinear in shape, and provides the proper field flux path through field elements of permeable lamination, contacting each end of the block.

The current, delivered by the output tube of the audio system of the usual receiver, is of comparatively high volta-ge and low current, whereas the armature of the speaker motor means is preferably driven by a current of higher intensity. Thus, step-down transformers are generally used, and wherethese are separate from the speaker, the relatively high current intensity from the transformer secondary to the actuating coil of the `speaker results in heat losses in the lead wires. The speaker disclosed herein is an improvernent, in that the armature actuating coil and the transformer secondary are formed by a single loop of relatively heavy metal of good conductivity, so that negligible heat losses result and a very good transfer of energy is had. This coil or strip, moreover, also serves as the mounting for the transformer` and helps in making a compact unit. Y

In order to provide a direct drive from the armature to the apex of the cone diaphragm, the connecting lever is centrally mounted in the armature at right angles thereto and passes through an opening in one of the eld elements provided by spacing apart two of the laminations which make up such element. The lever arm is also slotted or provided with an opening, which surrounds one leg of the actuating coil, so that strength is achieved without sacrifice of compactness and operating efliciency.

The motor frame is formed of two stampings of brass, aluminum, or other non-magnetic material, and provided with slots adapted to re ceive the ends of the laminations of the field elements. These slots, and spacing means, enable an assembly, wherein the eld elements, magnet block, armature, and actuating coil, are all held in an assembled unit through the use of only two rivets.

In the particular embodiment of this invention disclosed herein, a frame or basket I has mounted therein a diaphragm II, here shown as a cone. Motor means I2 is also mounted on the basket and is adapted to drive the cone diaphragm through the lever I3, connected to the apex of the cone II by the pin I4. 'I'he motor means I2 comprises a motor frame consisting of an upper stamping I5 and a lower stamping I6, both being of non-magnetic material, a field consisting of field elements II and I 8, and a block of magnetized material I9, an actuating coil or strip 20, an armature 2|, the connecting lever I3, and a transformer 22.

Considering the field in more detail, each field element II and I8 is composed of a number of laminations of highly permeable material, each lamination being substantially F-shaped. The block I9 of permanently magnetized material is either cubical or slightly elongated, and is adapted to be engaged and grippingly held by the bottoms or lower parts of the field elements depending beneath the arms which direct the field across the armature 2|. These upper and lower arms are adapted to lie immediately adjacent opposite sides of the armature, and to have the actuating coil or strip 20 extend therethrough between the upper and lower arms thereof.

By means of this construction, a strong permanent eld is developed across the armature at the desired place by the use of a relatively small block of the expensive permanently magnetized material.

The armature, best shown in Fig. 8, comprises a series of laminations 23, end pieces 24, rivets 25, and L-shaped mounting brackets 26 of springy metal. 'I'he lever I3 is rigidly mounted in the center of the armature by the rivets 25, and extends out at right angles thereto. This lever is provided with a slot or opening 21 therethrough, adapted to surround one leg of the actuating coil 20 to permit free play of the lever arm asfthe armature rotates slightly as a result of the spring in the mounting brackets 26.

The actuating coil 20, best shown in Fig. 9, is provided with a substantially square opening 28 near one end thereof, and an elongated opening 29 near the other end thereof, these openings being joined by the slot 30. The opening 28 is adapted to have the central leg 3|, or core of the transformer 22, pass therethrough, so that the primary coil 32 of the transformer is in substantial registry with this opening, and this end of the coil 28 acts as the secondary of the transformer. The other opening 29 is adapted to surround the armature 2l and to set yup a varying flux therethrough as a result of the variable current induced in the coil 20 by the transformer 22, and thus to drive the diaphragm I I of the speaker. The coil 20 is preferably of a strip of copper, shaped as shown,'and it acts not only as the actuating coil for the armature, and the secondary coil for the transformer, but also acts as the lead therebetween, since the two are really one integral loop or coil, and also as the mounting or supporting means for the transformer.

Referring more particularly to Figs. 1, 4 and 5, the assembly of the motor means will be seen. The upper stamping or frame piece I5 is provided with slots 33 and 34, having central strips or bars 35 and 36 left in place. These slots are adapted to receive the upper ends of the field elements I 'I and I8, and similar slots in the lower stamping I6 are adapted to have the bottoms or lower legs of the field elements project therethrough. These slots are so spaced that the bottoms of the eld elements I 'I and I8 make a tight gripping contact with the magnetized block I9. The spacers, as 35, space apart two of the laminations forming the field element I8 and make a slot or opening 3l, through which the lever I3 projects. The upper and lower stampings I5 and I6 are drawn together adjacent the holes for the

rivets

38 and 39, and the spacing at this point is accurately stamped. This is necessary, in order that the

rivets

38 and 39 will hold the entire structure together with the brackets 26 tightly gripped therebetween, and the actuating coil or strip 20 also tightly held between the strips of insulation 40, provided to prevent electrical contact between the coil and the frame. Thus, the entire motor means for the speaker is held in operative assembly by the two

rivets

38 and 39, and it is only necessary to mount the frame on the basket,las by the bolts 4I, and then solder or otherwise fasten the pin I4 to the lever I3.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims, in which it is my intention to claim all novelty inherent in my invention as broadly as permissible, in view of the prior art.

I claim:

1. Motor means for driving the diaphragm of a speaker of the character described, including: a movable armature of magnetic material; connecting means between said armature and said diaphragm; field elements of highly permeable material adjacent opposite sides of said armature and having substantially parallel portions extending therefrom; a motor frame of nonmagnetic material having slots therethrough, said field elements having portions extending through said slots; a relatively small block of permanently magnetized material gripped between the extending portions of said field elements whereby a permanent field flux through said armature is maintained; and means for setting up a second variable flux through said armature.

2. Motor means for driving the diaphragm of a speaker of the character described, including: a movable armature of magnetic material; connecting means between said armature and said diaphragm; field elements adjacent opposite sides of said armature and having substantially parallel portions extending therefrom, said elements comprising laminations of highly permeable material; a relatively small block of permanently magnetized material between the extending portions of said field elements, whereby a permanent field flux through said armature is maintained; a motor frame so constructed and arranged that it supports saidV field elements and causes them to grippingly support said block; and means for setting up a second variable flux through said armature, whereby movement of said diaphragm is effected.

3. Apparatus of the character claimed in claim 2, wherein two of the laminations of one of said eld elements are spaced apart to permit said connecting means to pass therebetween, and said block is magnetically parallel to said permanent eld.

4. Motor means for driving the diaphragm of a speaker of the character described, including: a frame having slots therethrough; eld elen ments having extended portions and at least two arm portions substantially perpendicular to said extended portions, the top and bottom of variable flux through said armature, whereby movement of said diaphragm is effected.

5. Apparatus of the character claimed in claim 4, wherein said lever passes between spaced laminations in one of said eld elements.

6. Apparatus of the character claimed in claim 4, wherein the block is so arranged that the flux therethrough is parallel to that of said field.

WALTER J. PAREDES.