US2124338A - Loudspeaker - Google Patents

Description

July 19, 1938. J p, QUAM 2,124,338

LOUDSPEAKER Filed April s, 1935 2 sheets-sheet 1 July 19, 193s. J. P. QUAM 2,124,338

I LOUDSPEAKER Filed April, 1935 2 Sheets-Sheet 2 catto" speaker.

Patented July 19, 1938 uNrrl-:D s

' SEP 9- oF-Fic f l1.oUlisrlinKFR James P. Quam, Chicagm'lll., assigner to Quam- Chicago, Ill., a corporation Nichols Company, of Missouri Application Aprii s, 1935, seal No.` 14,389

' 16v Claims.

My invention relates in general vto loudspeakers, and particularly loudspeakers with the cone type diaphragm and a vibratory unit therefor, ordinarily known as a magnetic type speaker.

Diiculty is encountered kin, the presentmagneticvr type loudspeakers in thatitis not possible to obtain the volumeor `the faithfulness of reproduction over the entire band of frequencies `obtained from the dynamic,` type loudspeaker.

Chatteringand distortionroften developwhen the speakeris operated at high volumes so as to impair reproduction.

A further disadvantage to the present magnetic type speaker, in comparison. with a dynamic speaker, is they fact that it is less sturdy, ,and has ashorter life. Furthermore, Yit does' not lend `itself to shipment and handling as satisfactorily Aas thedynamic type.- g 5.

It is an object of my inventiony ;to `provide an improved magnetic. type of loudspeaker.

A `further object `is to provide an improved vibratory Aunit for a cone typey diaphragm..loud

It is also an object to provide .a magneticv type loudspeaker which, will,y faithfully reproduce. at large volume aradioy broadcastover substantially the entire band of frequencies.

One of the features of my-improved driving -unit isthe provision vof alaminat'ed. permanent magnet comprising closed .ring-shaped body members, in which said laminations are punched out on apunch press. v .f An additional feature isftlie,` provision of a -pair of laminated pole pieces. adapted; to carry a `laminated yarmature anda field coil therebeytween, with thethree -elements designed to be mounted between the laminations of the vperma nent magnetas afframe.furtheI elements.

-A further feature of my invention is ythe provision of a vibratory unitior a loudspeakerwhich may be completelyassembled and then quickly mounted directly onthe usualframe support yfor the cone-shaped-diaphragm ofthe'speaker. y vIt is also al featureotmyinvention to proalong the une 5 'cf Fig. 3.

will be apparent from theiollowing descriptinn iftaken with the drawings, in which: r

Fig. 1 is a front elevation of the completely assembled loudspeaker.

Fig. 2; is a rear elevation thereof.

Fig. 3 is a fragmentary .rear elevation partly in 'M- section of the vibratory or driving forthe speaker.` f.

Fig.I 4 is a similar view to that of Fig. 3,shovv ing the pole pieces outside the armature.

Fig. 5 is a sectional view of the driving unit ing in addition a bi-part clampfor rigidly clampt1 0 Fig. 6" isa sectionall vieW of the drivingy unit line 6 6 cf Fig. 3.r

Fig. 7 is a sectional view of the vibratory'unit as mounted on the cone housing taken along the mm1- 1 of Fig. 3. v

as mounted on the conehousing'taken'along the 15 Fig. 8 is a View of the driving unit, particularly 2 0 piece, armature and'vcoilmem- Uf the magnet, pole bers.

Fig. 9 is a top elevation showing the manner in which the laminations of the pole pieces are stamped out of a single strip of` steel-With 2x25 minimum of waste inthe strip. z

i Fig. 10 illustrates a'modication of fthe closing plate for the vibratory unit housing.

' In practicing my invention I provide'a loudspeaker having a cone-shapedy diaphragm supported, on an annular frame, and asty-lus extend-*fil ing rearwardly Afrom the center ofthe cone.4 vI provide a vibratory unit for the -diaphragm to be mounted at thevrear `of the. cone support and comprising a laminated permanent magnet in-` 35 cluding a` plurality of closedring -magnetSfServing as a frame and having a central aperture kto carry a pair of Y-shaped laminated pole pieces which in turn support a laminated armature and :an encircling energizing coil intermediate saidn40 pole pieces. A driving arm extends from Within the armature to the stylus on the diaphragm, `and a non-magnetic housing is providedvaround vthe entiredriving lunit'when assembled on the cone support.

Referring now` to the drawings, inthe loudspeaker of my invention I provide the usual coneshaped diaphragm l0 supported onthe'annular rim of a frame I.|,` having a pair of rearwardly protruding legs IZJ to carry a slotted mounting strip I3. The strip I3 is preferablyV Welded to the legs l2 of the frame. A stylusv I4` is Vrigidly secured at the apex of the coneto extend rearwardly through the mounting strip. i

Inaddition to obtaining marked :improvement in the lfaithfulness of reproduction and the volume in the commercial embodiment b'ffmyo marient magnet comprising a pair of ring-shaped alo the steel issoft enough to permit stamping,

laminations I6 and I1 stamped from a suitable magnet steel preferably in the shape of a substantially oval ring with an elongated aperture in the center thereof. If I wish to increase the field strength I may employ four, or even more laminations in the permanent magnet, using an even-number so that they may be divided with an equal number on each side of the pole pieces as will be hereinafterv described. In a commercial embodiment I have stamped the laminations from steelstrips or sheet steel 1/8 inch thick in which but hard enough to provide the necessary retentivity value. The individual laminations of the magnet are assembled as shown particularly in Figs. 6 and 7 to serve as a frame on the inside and outside ofV a pair of Y-shaped laminated pole pieces I8 and I9 including a plurality of laminations with extendinglegs 2| and an integral tail piece 22. A pair ,of apertures 23 in the tail portion 22 of each of the laminations of the pole pieces provide holes the length of the pole pieces to receive fastening rivets 20.

The individual laminations ofthe pole pieces `I8 and I9 are preferably stamped from relatively thin silicon steel, and with the retaining rivets extending only through the tail portion of the laminations there might be a tendency for the legs 2| to spread slightly in a longitudinal direction. To overcome this difficulty I provide silicon steel laminations over the central portion 'indicated by the letter A and steel laminations of greater thickness at each end as designated by the letter B. This assembly is also indicated by darker and lighter portions in the pole pieces of Fig. 8. The steel laminations are of suflicient rigidity to prevent the longitudinal spreading of the legs of the intermediate silicon steel laminations when secured together by the rivets.

A laminated armature 24 is provided for mounting between the pole pieces and includes a thin knife-edge driving arm 26 having a right-angled ,extension 21 of the same area as the laminations for the armature, so that the arm may be fitted into the center of the armature in the vertical plane of -the stylus I4, to move as an integral portion ofthe armature. Apertures 28 are provided in each of the armature laminations as well as in the extension 21 to receive retaining rivets to hold the laminations ofthe armature together. A central aperture 29 is also provided to receive a mounting spring 3| extending the entire length thereof and protruding a short distance from l each end thereof. The mounting spring is preferably a phosphor bronze alloy, although other materials with the necessary flexibility and .strength'may also be employed. The .mounting spring must of course be stiff enough to insure a faithful movement in response to a variation in impulses applied, and stiff enough so that the armature wont hit against the pole pieces in vibI'at-ng'.

As will be noted from a consideration of Figs. 6 and 7, the armature rocks about the mounting spring 3| as a central axis, although the only twisting of the spring that actually occurs is that between the armature and the torsion blocks as will be hereinafter explained. The mounting spring of course is rigidly soldered into the central vaperture 29 so there is no relativemovement as between the spring and the armature body itself. Torsion or mounting blocks 32 of a non-magnetic metal fit over the ends of the spring 3| and are slightly spaced away from each end of the ar mature body itself to permit vibration of the armature itself, and spaced far enough away so that the block may be soldered to the end of the spring without danger of soldering the block to the end laminations of the armature. 'Ihe torsion blocks are rigidly secured between the ends of thelegs 2| on the pole pieces and are initially alined by means of notched portions 33 on each of the four corners of reach of the blocks 32 to correspond with the ends of the legs 2|. The torsion blocks are of such a size that when the armature is mounted between the pole pieces, an air gap 34 is provided between the armature and the ends ofthe pole pieces preferably of .005 inch. From the standpoint of sensitivity it is of course important to keep this as small as possible. However,` I have obtained satisfactory operation with an .air gap varying `from .004 to .00'7 inch for instance.

The channel between the `legs 2| of the pole .pieces is of such a size as to receive the frame of an energizing coil 3B. The energizing coil has a central elongated aperture wide enough to permit the insertion of the torsion blocks 32 as shown 3 andfi and preferably of particularly in Figs.

such a width thatfthe projections on the blocks willengage the inner insulating ring 35 on the coil vwhen the pole pieces, armature and coil are clamped together. The energizing coil is wound gwith any desired wire in the usual manner.

To assure arigid assembly of the pole pieces,

`armature and energizing coil, I employ a bi partspring clamp including a pair of clamping members 31 and 38 bent to engage the top of the tail portion of the pole pieces at C and D and .rounded out at the corners to remain out of engagement with mounting screws for the entire driving unit as will be hereinafter described. The

ends of the clamping members are bent outwardly and apertured in the usual manner to receive bolts 39 of non-magnetic material and Vpreferably brass. Upon tightening the clamp bolts, the ends of the legs of the pole pieces engage the torsion blocks so tightly that there is ,no possibility of looseness or chattering with ,repulsion or attraction of poles of like or opposite polarity, twisting the mounting spring therewith.

A very rapid and simple assembly of the entire unit is provided in first assembling the laminated pole pieces and laminated armature with the` driving arm therein. The central aperture 29 in i means of the alining notches 33.

`ment around the pole pieces.

ei'ipens'i've unit is provided, and at the same time the armature formed bythe various apertures in each of the laminations is of a diameterapproximately the width of the phosphor bronze mounting spring 3|. This aperture is reamed out at its ends as shown in Fig. 5 to a depth of approximately 1A; inch. 'Ihe spring 3| is then inserted into the aperture, a drop of acid asflux is placed in the aperture, and the armature dipped into a solder bath to rigidly solder the spring into the armature body. Any excess solder is wiped oiT and the torsion blocks 32 are fitted over the "ends ,of the spring, spaced away from the laminations of the armature. The springs are then soldered to the block on the outside thereof. After the eld coil 35 is inserted between the legs of the `pole pieces the armature is placed in the central aperture of the coil 'and properly alined by The clamp is then positioned and drawn up to a tight engage- A jig is employed for alining the elements of the assembly.

To prevent dust, dirt or moisture from getting into the driving unit, I provide a non-magnetic housing 4l including a closed cap 42 and a bottom member' 43. To complete the assembly of the vibratory unit, the motor assembly comprising the pole piece, armature, and coil, clamped together by the bi-part clamp, is positioned between the two laminations I6 and l1 of the permanent magnet with the shoulders 44 on the pole pieces fitting into the alining notches 46 in the laminations. The cap 42 is then placed over this assembly and the bottom member 43 properly positioned, after which this assembly is mounted on the mounting strip .I3 by bolts 41. A pair of bolts 48 are insertedthrough the necessary apertures in the lower portion of the assembly to hold the members of the permanent magnet together over the pole piecesand close the housingr over the entire driving-unit. In the meantime the split end 5I of the driving arm has been placed over the stylus I4 and when soldered thereto completes the assembly of the driving unit on the cone support. Suitable wireleads 52 extend from the field coil 36 to be soldered to mounting posts 53 eyeletted onto the mounting strip I3. Lead wires 54 then extend from the eyelets to the radio receiver.

Inasmuch as dirt and moisture, collecting in the air gap would impair the operating eiciency, it is very desirable to employ the cap 42 and bottom plate 43 to house the unit. It is understood, however, that the vibratory unit may, if preferred, be mounted directly on the cone support with the bolts 41 and 48 as described.

.A modication of the bottom member of the housing is illustrated in Fig. 10, wherein a fiber insulating strip 56 is assembled in the same manner as the member 43. I also utilize the member 55 as a terminal strip by eyeletting a pair of, terminal lugs 51 thereon. The wire leads 52 are brought to the eyelets and soldered thereto, and the wire leads 54 from the receiver are soldered onto the terminal lugs 51, thus eliminating the lugs 53.

'Io further protect the vibratory unit against moisture and dirt when employing a housing, I slit a piece of thin surgical rubber 58 and slipit over the driving arm before the unit is placed against the bottom member of the housing. This effectively closes the aperture 59 in the bottom member through which the arm extends.

In providing punched-out laminations for the permanent magnet, and stampings for most of the remaining parts of the vibratory unit, an inlble of long and efficient use.

a very sturdy one. The various parts of the unit are very simple, anddue' to their design may be very readily assembled. It is possible to ship the unit disassembled'to its place .of use, and there .35 to be very quickly and cheaply assembled. The vibratory unit is exceedingly sturdy and capa- Inthe commercial embodiment ofthe invention I obtain marked improvementv in f reproduction over the entireulo frequency range, and a'large increase in volume over the magnetic type speakers in use at the present time.

Although I have described my invention in its preferredv embodiments, it is understood that 1;-15 aml not limitedthereby, but limit the invention only Vby the scopeof the appended claims.

I claim:

1. A vibratory' unit for a magnetic speaker, .in-

cluding a motor assembly having a pair of poleszo pieces, an armature supported for oscillatory vibration between the Ypole pieces and having a driving member in connection therewith, means for yretaining said pole pieces rand armature in 'x'ed relation,.and a plurality ofpermanent mag-M25 nets including a continuous, flat, apertured magnet on each of two sides of the pole piece'varrnature assembly engaging the pole pieces, and of such a size and shape as to extend considerably beyond the edge of the assembly in oppositefs30 '.directions, and positioned at right angles to the line .of movement of said driving member to serve as a mounting frame for the pole piece 1 armature assembly.

permanent magnet mounted on said motor assembly 'as an assembling frame therefor.

3. A vibratory unit 'for a loudspeaker including a pair of oppositely positioned Y-shapedy pole pieces each having a pair of forwardly extending 50 legs with a'channeltherebetween, a tail portion extending rearwardly from the channel and of the same size assaid channel', an energizing coil carried in the oppositely positioned channels, anarmature supported between the pole pieces1.55 and 'within the field coil, a` permanent magnet comprising a plurality' of ring-shaped members with a mem-ber restingon one side of each pole piece 'taiL'iand another member resting on the other sid'eof .each pole piece tail.

4. A vibratory unit for a loudspeaker comprisinga lpermanent magnet, a vibrating armature,a laminated pole piece on each of two sides of said armature, each of said pole pieces comprising a plurality of `relatively thin Y-shaped laminations having a pair of forwardly extending' legs dening a channel therebetween and a tail piece extending rearwardly from the leg pory tion and of substantially the same size as said' channel, a retaining rivet through said tailv pieces, and vmeans for preventing a longitudinal spread of the pole piece lat the leg portions, said means comprising relatively heavy laminations assembled'at each end of the relatively light lamina- `tion .assembly with said heavy laminations hav` 75 ing greater rigidity than said relatively light laminations.

5. A loudspeaker motor including an armature, a spindle rigidly secured to said armature, holders carrying said spindle and positioned adjacent to said armature but being slightly wider than said armature, a pair of pole pieces having their active faces bearing against opposite sides of said holders and accurately spaced by said holders to permit operation of the armature therein, and means for supporting said pole pieces and supplying magnetic flux thereto.

6. A loudspeaker motor including an armature, separate pole pieces positioned on opposite sides of said armature with end faces toward said armature, and .a centrally apertured ring-shaped permanent magnet engaging a side face at right angles to an end face of each of said Dole pieces whereby it may firmly engage both of said pole pieces irrespective of their exact dimensions and rit in the vertical direction through the two pole pieces and armature, said pole pieces being laminated, and means being provided for clamping all of the laminations of the pole pieces against said magnet to insure their proper vertical alinement.

7. A vibratory unit for a loudspeaker, including a pair of oppositely positioned laminated pole pieces, each including a plurality of Y- shaped laminations with a pair of forwardly extending legs having a channel therebetween and a tail portion extending rearwardly from the channel, an energizing coil, and an armature supported between the pole pieces, and a ringshaped permanent magnet in engagement with the pole pieces on the tail portion thereof.

8. In a vibratory unit for a loudspeaker, an armature unit comprising a pair of spaced apart non-magnetic stationary torsion blocks, a supporting spring rigidly secured at its ends at the blocks, an armature member rigidly secured on said spring with the latter extending through the longtudinal center of the member from end to end, said member comprising a plurality of laminations with a one-piece diaphragm driving element positioned in said member intermediate the ends thereof and having a body portion conforming in shape precisely to the laminations in said member, with an integral elongated driving arm, flat and of the same thickness as'the body portion extending away from said body portion in said armature and at right angles thereto for'connection with the diaphragm.

9. A vibratory unit for a loudspeaker including a vibratory armature comprising a plurality of apertured laminations, a diaphragm driving member having an apertured body portion conforming in shape to said laminations and positioned corresponding thereto in said armature intermediate the ends thereof and a knife-edge elongated driving arm extending away from the body portion in the plane of said body portion and integral therewith, and a mounting spring for the armature extending through the aperture in each lamination and the aperture in the body portion of the driving member, with said mounting spring rigid with respect to the laminations and driving member.

10. A vibratory unit for a loudspeaker including a pair of oppositely positioned Y-shaped polepieces each having a pair of forward legs and a tail portion, an apertured energizing coil carried in the recess formed by the legs of the pole-pieces, an armature in the aperture of the coil having supporting means carried by the pole pieces,- and an apertured permanent magnet carried on a corresponding face of each of the tail portions with a portion of each pole-piece extending into the magnet aperture.

11. A vibratory unit for a loudspeaker including f. 5 a pair of Y-shaped block-like pole-pieces, each having a pair of forwardly extending legs and a tail portion, with said pole-pieces positioned with the legs facing each other, an energizing coil carried in the oppositely disposed recesses in the l0 pole-pieces formed by the legs, and an armature within the energizing coil having a stationary carrying plate at each end supported by the active faces of the pole-pieces, and a closed substantially oval shaped permanent magnet resting on a cor-15,15 responding side of each of the tail portions of the pole-pieces, with a corresponding forward leg of each pole-piece lying in the aperture of the magnet and acting with the magnet to position the vpole-pieces with respect to one another and ther-20 armature plate therebetween.

12. A vibratory unit for a loudspeaker including an apertured plate-like permanent magnet, a vibratory armature, and apair of block-like Y- shaped pole-pieces supporting the armaturel 25 therebetween, each pole-piece having a recess on at least one side of the tail portion corresponding in depth substantially to the thickness of the `permanent magnet with the recesses on corresponding sides of the two tail portions, and said30 permanent magnet lying on the tail portions at the corresponding recesses with the forward leg on said recess side of each pole-piece positioned in the magnet aperture.

13. A vibratoryunit for a loudspeaker includingiV35 a pair of spaced apart pole-pieces with the active face of Yeach pole-piece oppositely disposed from the other, a pair of spaced apart non-magnetic plates between the active faces of the pole-piecesn and supported solely by engagement with said* faces, a block-like armature between said polepieces and said plates, a spindle irremovably secured to said plates and extending through the armature in the longitudinal axis thereof to sup-,w port the same for vibratory movement, and ai permanent magnet resting upon a corresponding outside face of each pole-piece with such outside faces at right angles to the active faces of the pole-pieces, and said magnet acting to position, said pole-piece-armature assembly elements with"50 respect to one another and acting as a mounting frame for the vibratory unit.

14. A vibratory unit for a loudspeaker comprising a pair of oppositely disposed single unit.l pole-pieces, a laminated armature mounted be#4 tween the pole-pieces for oscillatory Vibration, means for supporting said armature comprising a stationary torsion block at each end thereof retained between the pole-pieces in engagementfo With the active faces thereof, a mounting spring irremovably secured at each end in a torsion block and extending through the armature in the longitudinal axis thereof in a line at right angles to the line of movement of the diaphragm of the 65 loudspeaker.

15. An electromagnetic loudspeaker motor including a continuous oval shaped permanent magnet having an elongated central aperture, a pair of opposed pole-pieces positioned against ondface of the magnet with each pole-piece having a portion extending into the aperture of the magnet to position said pole-pieces with respect to said magnet, and a clamp around the pole-pieces on an outside face of each at right angles to the275 magnet engaging face to draw the pole-pieces toward one another.

' 16. An electromagnetic loudspeaker motor having a pair of opposed pole-pieces, an armature unit retained by the pole-pieces between the active faces thereof, a permanent magnet for the polepieces, and a spring clamp around said pole-pieces enga-ging an outside face of each parallel to the active face of that pole-piece and adapted to be adjustably tightened to draw the pole-pieces toward one another to rigidly retain the armature unit therebetween.

JAMES P. QUAM.

Images