US2020211A

US2020211A - Loud speaker

Info

Publication number: US2020211A
Application number: US750429A
Authority: US
Inventors: James P Quam
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-10-29
Filing date: 1934-10-29
Publication date: 1935-11-05
Anticipated expiration: 1952-11-05

Description

Patented Nov. 5, 1935 UNITED STATES 2,0zaz11 PATENT OFFICE 9 Claims.

My invention relates to loud speakers, and has to do more particularly with the loud speakers having the cone type of diaphragm. In some respects my improvements are applicable to the cone type of diaphragm whether used with or without the dynamic drive, that is, the cone may be driven either by a dynamic voice coil or a vibrating armature as ordinarily employed and controlled by the voice currents.

The present application is a continuation in part of my co-pending application Serial No. 670,865, filed May 13, 1933.

An object of my invention is to provide an improved and simplified structure of the above character, cheap to manufacture, easy toassemble, and effective in operation.

A further object is to provide a simplified diaphragm or cone supporting frame stamped from sheet/metal in a form to carry a one-piece reshaped outer pole-piece magnet at the rear and welded thereto in a permanent and irremovable fastening.

It is also an object of my invention to provide a simplified structure in which one of two parallel leg portions of the outer-pole piece is welded at the rear of the diaphragm support in an-initial unit assembly, a field coil is then slipped into the pole-piece and a core for the pole-piece is forcedinto the other leg portion of the polepiece in a driving fit to be supported therein and properly centered in the first leg portion entirely by said driving fit.

One of the features of my invention resides in an improved, cone supporting frame, that is, the frame supports the cone diaphragm, resulting in a simpler and cheaper construction. This feature resides in a frustum-like' conical support or framework for carrying the cone diaphragm, which framework has an inwardly extending flange for supporting the field coil, and outwardly extending ears at the apex end of the frame for carrying the cone supporting spider and other elements. v I a I Another feature of my invention is the welded fastening of the pole-piece of the diaphragm support. This fastening not only facilitates assembly but with these members in alignment before welding, they remain permanently so after the operation as contrasted to other types of fastening, where due to production inaccuracies in holes and the positioning thereof, the elements are sometimes put under tension in a jig and then spring back upon removal. Qther types of fastening have been found to work lqose during the life of the speaker, but the welding is permanent.

For a better understanding of my invention reference is to be had to the accompanying drawing, in which: 5

Fig. l is a side elevation of the preferred form of my invention.

Fig. 2 is a bottom plan view of the cone supporting frame.

Fig. 3 is a top view of Fig. 2.

Fig. 4 is a left end view of Fig. 3 with part of the base broken away.

Fig. 5 is a right end view of Fig. 1 showing more particularly the method of mounting the transformer on the cone frame; and

Fig. 6 is a modified form of cone supporting frame showing a frame adapted to take a larger size of cone than that shown in Fig. 1.

Referring now more in detail to the preferred form of construction as illustrated, I provide a suitable field magnet, the one illustrated having an outer U-shaped pole piece 8 enclosing a magnetizing coil 9 supported upon a, central core III driven into one leg of the magnet and extending up into the other to provide the usual annular air gap into which the voice coil I I extends.

A cone support A is provided in which the cone I2 is supported at its annular flange I3, the said cone carrying the voice coil I I and supporting spider I4. This spider is of the usual thin linen reinforced material, stiff enough to act as a support, but permitting free vibration of the cone with the spider arms fastened at their ends.

Now, as to the construction of the cone frame, this is preferably in the nature of a frustrum of a cone in which the base end I3 carries the base flange of the cone, with the apex end of the frame arranged to support the spider and field magnet. To this end the frame has an inwardly extending fiange for supporting the field magnet, preferably in the form of inwardly extending ears I5 and I6 separated sufficiently to permit the voice coil II to pass between these ears as shown in Fig. 1.

The field magnet and cone frame are preferably secured together by spot welding the ears V I5 and I6 directly to one leg of the outer pole piece. of the field magnet.

Now as to the means for supporting the ends of the arms of the voice coil supporting spider It, I provide a pair of outwardly extending ears H and I8 preferably formed out of the sheet metal of the side wall of the frame A. Thus the nds of the spider arms are fastened upon these ears by suitable studs l9 and 20 with lock nuts thereon.

By the arrangement above referred to, that is, with the flange or inwardly extending ears I 5 and I6, and the outwardly extending ears I1 and I8, I provide not only a very simple and cheap construction, but also am enabled to use the same magnetic structure and same length of spider with different diameters of cones. For instance, in the speaker illustrated in Fig. 1, which is full size, I employ a 5-inch cone. This is one of the smallest sizes now ordinarily employed. Should a larger cone be required, the base end 13 of the frame A is made larger, as indicated in Fig. 6, with the side or angular portion 2| of the frame extending at a more acute angle than in Fig. 1. The apex end of the cone, that is, that end carrying the ears l6 and I8, remains of the same diameter as in Fig. 1, so that although a larger cone is provided, I still can use the same spider and magnet construction. The reverse is also true, that is, where the larger cones are employed, and more room is provided at the base of the frame so that a suitable spider I4 may be employed, when a smaller cone is to be provided the same magnet structure and spider I4 may be employed by having the spider supporting ears I! on the outside of the frame and permittin the arms of the spider to extend through the side walls of the frame to the point where they are supported by said ears.

In connection with the outwardly extending ears, I also am enabled to use one of them for supporting the usual transformer 22 by securing a mounting plate 23 to the ear [8, preferably by welding. The transformer is then attached to this plate 23 in any suitable manner, preferably by a pair of

lugs

24 and 25 which are punched out of the plate 23 and are passed up through openings in the fastening plate 26 of the transformer.

Another simplified construction which I have provided is in the method of supporting the ends of the conductors 21 of the voice coil. For this purpose I provide ears 28 through which an eyelet 29 is passed and insulatingly supported by these ears through the use of a pair of insulating washers 30, one of which is secured against each face of the ear 28 and through which the eyelet 29 is passed after which it is curled over each washer. A voice coil conductor 21 is then passed into the eyelet 29 and soldered thereto, after which the corresponding conductor 3| from the transformer is soldered to the outside of the eyelet 29.

In assembling the speaker, I preferably first weld one leg of the outer pole piece 8 of the field coil to the inwardly extending ears I5 and I6 of the cone supporting frame. I then assemble the field coil by placing the coil 9 over the core l0 and driving this core into the lower leg of the outer pole piece with the free end of the core providing an annular air gap in the other leg.

I now take the cone assembly consisting of the cone I2, voice coil II and spider I 4, and place it in the cone supporting frame A with the voice coil ll suitably centered in the air gap and the ends of the arms of the spider l 4 are now attached to the studs l 9 and20. The voice coil conductors 21 are now soldered to their terminals 29 after which the transformer 22 is put in place and the terminals 3| thereof secured to their corresponding eyelets 29. M I claimr 1. In a loud speaker, a frustum-like one-piece conical frame stamped from a sheet of metal for supporting a cone diaphragm, said frame having a rim and free-ended brackets slanting inwardly therefrom and having inwardly-extending cars at their apex ends, and a field magnet ir- 5 removably mounted on said inwardly-extending ears, and outwardly-extending ears at the apex ends stamped from the brackets themselves and extending outwardly therefrom for supporting a cone-supporting spider extending through said 10 brackets.

2. In a dynamic loud speaker a cone, a voice coil unit mounted directly on'said cone, a field magnet having a core and a bent-to-shape polepiece having substantially parallel side portions 15 with one side surrounding said core to form an annular air gap in which said voice coil operates, and a one-piece metallic cone support having an outer rim 'to which said cone is secured, having attachment ears substantially parallel with said 20 rim and permanently and irremovably secured to the face of said side portion independently of any securing formations on the joined members, with said rim concentrically aligned with said air gap, and having an apertured wall between '35 said rim. and attachment ears, outwardly-extending ears integrally formed on said cone support near said side portion, and a spider extending through the apertured wall, secured to said ears and supporting said voice coil unit accurate- 30 ly aligned in said air gap and being flexible axially of said air gap to permit said voice coil to vibrate therein.

3. In a dynamic loud speaker a cone, a voice coil unit mounted directly on said cone, a field 35 magnet having a core and a U-shaped bent-toshape yoke having one leg surrounding said core to form an annular air gap in which said voice coil operates, and a metallic cone support having an outer rim to which said cone is secured and 40 having attachment ears substantially parallel with said rim and spot welded to the face of said leg with said rim concentrically aligned with said air gap, and outwardly-extending ears integrally formed n said cone support near said 45 leg, and a spider supporting said voice coil unit accurately aligned in said air gap and being flexible axially of said air gap to permit said voice coil to vibrate therein and being secured to said ears at points outside of the contour of said 5 cone support and spaced laterally with at least one ofsaid points beyond the pole-piece whereby the amplitude of vibration for said spider is relatively large.

4. In a dynamic loud speaker, a frustum-like 55 metal diaphragm frame having an annular rim at its face and walls extending inwardly to the apex of the frame, a diaphragm rigidly supported in said frame on said rim, a field electro-magnet having a one-piece outer pole-piece with substan- 60 tially parallel side portions lying in planes parallel to the plane of the face of the frame, with one of said side portions permanently and irremovably mounted at the apex of the frame, diaphragm driving means carried centrally of 65 the diaphragm, and aligned in an opening in one of said side portions, whereby said pennanent and irremovable mounting of said outer pole-piece on the diaphragm supporting frame maintains said frame, pole-piece and diaphragm 70 driving means in permanent alignment.

5. In a dynamic loud speaker, a frustum-like metal diaphragm frame having an annular rim at its face and attachment portions at the apex thereof, a diaphragm rigidly supported in said 75 frame on said rim, a field electro-magnet having a one-piece outer pole-piece with substantially parallel side portions lying in planes parallel to the plane of the face of the frame, with one of said side portions welded to the apex of the frame, diaphragm driving means carried centrally of the diaphragm, and aligned in an opening in one of said side portions, whereby said welding fastening of said outer pole-piece on the diaphragm supporting frame maintains said frame, pole-piece and diaphragm driving means in permanent alignment.

6. A dynamic loud speaker comprising a frustum-like metal diaphragm frame having an annular rim at its face, and attachment portions at the apex thereof, a diaphragm supported on said rim in said frame, and a one-piece outer polepiece having an outside face portion and an inside leg portion, substantially parallel over their length, and said portions lying in planes parallel to the plane of the face of the frame, with said inside face portion of the outer pole-piece permanently and irremovably mounted at the attachment portions of the frame and retained in permanent alignment therewith independent of any securing formation in the joined members.

7. A dynamic loud speaker comprising a onepiece sheet metal diaphragm sup-porting frame with an open face, and attachment portions at its rear end, a diaphragm supported in the frame, and a one-piece outer pole-piece having an outside face portion and an inside face portion substantially parallel over the length of the portions and lying in planes parallel to the face of the frame, with said inside face portion permanently and irremovably secured to said attachment portions to maintain said pole-piece in permanent alignment with said frame independent of any securing formations in the joined members.

8. A dynamic loud speaker including a diaphragm, a diaphragm support, a voice coil for operating said diaphragm and an electro-magnetic field magnet including a one-piece polepiece pressed to shape having two parallel side portions, said pole-piece mounted on said dia- 5 phragm support independently of any securing formations in the support and pole piece, said pole-piece having a core attachment opening in one of said two side portions and a voice coil opening in the other side portion, and a one-piece core 10 extending into said core attachment opening and confined therein with radial pressure between said side portion and said core, and said core being centered in said voice coil opening independently of imperfections of parallelism between said side 15 portions. 9. A dynamic loud speaker comprising an openfaced diaphragm supporting frame having attachment portions at the rear thereof, a diaphragm supported on the frame, a one-piece outer pole- 20 piece having a pair of substantially parallel side portions secured at one side portion at the rear of said frame in a permanent and irremovable manner to maintain said frame and pole-piece in permanent alignment, said pole-piece having an 25 opening in each side portion, a core of magnetic material retained in one of said openings by a driving-fit between the end of said core and the inside surface of the opening, with the other end of said core extending into the other of said openings to provide an annular air gap, a voice coil in the air gap to drive said diaphragm, with said pole-piece and frame assembly, and polepiece and core assembly maintained in permanent alignment by the manner in which said elements are secured together to cause all of said elements to remain in permanent alignment with respect to one another.

JAMES P. QUAM.