US1630009A - Translating device - Google Patents

Description

M. c. HOPKINS May 24, 1927.

TRANSLATING DEVICE 7 Filed June 1925 2 Sheets-Sheet 1 INVENTOR /74/?c06 [fla /rm:

ATTORNEY May 1927' M. c. HOPKINS TRANSLATING DEVICE FilBdJune 1925 2 Sheets-Sheet 2 "mvENTbR Mica; (fla M45 WWW ATTORNEYS Patented May 24,1927.

- UNITED STATES PATENT OFFICE.

MARCUS C. ITOPKINS'OF BROOKLYN, YORK, ASSIGNOR, BY DIRECT AND MIllSNE ASSIGNMENTS, T O HOPKINS GOBPQRATION, A CORPORATIOH Olli DELAWARE.

TRANSLATING' DlEVICE.

Application filed June 6, 1925. Serial No. 35,425.

This invention'relates to electrical movements for translating varying electrical impulses'into mechanical motion, and aims particularly to provide an electrical movement suitable for' use with radio loud-speakers, line-wire receivers and the like. This electrical movement has special advantages 4 operation with a loud-speaker diaphragm of the conical type, I have hereinafter described it in conjunction with a diaphragm of that type and particularly one somounted as to permit that free bodily movement of the cone which I have found best suited to give accurate tone production or reproduction.

Claims on the novel cone and its mounting, as disclosed in the present application, are made in my co-pending application, Serial No. 34,255, filed June 1st, 1925. Other cones and other mountings can be used in conjunction with the electrical movement pole piece and-on each of them there is claimed herein, but for best results there must be correct coordination between the electrical movement and the vibratory diaphragm. Due regard must be had to the weights of the several moving elements and to the magnitudes of their movements.

In'the preferred embodiment of my present invention the electrical arrangement is such that thevibration of the armature is of small amplitude.

The electrical movement of the present invention includes a very rigid vibratory armature or reed, one end of which is se curely anchored, and the other end of which is free to vibrate. -The free-end portion is normally disposed midway between two electro-magnet poles-which are in turn secured to one pole of a strong permanent magnet, so that' both electro-magnet poles have the same normal polarity and normally exert equal and opposing forces on the free end of the armature. The two electromagnet poles are'those of a single soft iron by those mounted a coil through which the actuating or speech current circulates, thereby causing fluctuating differences of magnetic attraction between the armature or reed and the electro-magnet poles. The structure may be regarded as including a polarizedreedwith 1ts free end positioned between opposing speech coils through eitheror both. of which the magnetic flux of said reed may pass. Current fluctuations in the speech coils cause the armature or reed to vibrate correspondingly and the vibrations thus setup in the reed may be representative of and capable of being translated into sound waves.

I have discovered that distinctly improved to the armature canbe found by trial.-

Under these conditions the amplitude of vibration of the diaphragm is less than the amplitude of vibration of. that portionof the armature which is directly acted upon by the electromagnet. This is contrary to the usual loud speaker. arrangement, wherein a step up actuation of the diaphragm is pro-,

vided for. My present arrangement is particularly suited for use with a conical diaphragm which is very rigid and light in weight and restrained at the periphery as little as possible, so that the diaphragmarmature, the natural frequency may vibrate substantially as a'wh'ole instead of bending in the manner of an ordinary diaphragm. Although the best results in radio and line wire receivers are realized only with a very rigid, light and freely movin diaphragm, still, fair'results may be had with a diaphragm which could not be regarded as meeting those qualifications, and the invention should, therefore, notbe construed as limited in those respects except in'so far as such limits are included in the appended claims. 4 e

Other features, characteristics and ad- Figs. 3, 4 and 5 are side, top and rear. views, respectively, of the electrical move-' ment used for actuatin the diaphragm;

Fig. 6 is a view part y in cross section of the electrical movement and on a larger scale than 3, 4 and 5;

Fig. 7 is a view partl' in cross section taken along the lines 7 of Fi 6, and

Fig. 8 is a rear elevation of t e receiver with the ,electrical movement removed.

The conical diaphra 1 is preferably of lar diameter, usua y more than nine inc es,,andygenerally is made wholly or in part of paper in order that it ma be of light we ht. The paper should stifi.

A long fi red paper of porous structure and free from loading will serve well, sizing should be of the fibers beand not of the sheet after it mod 11' A layer of varnish and an fore fe tin has been it) or otherlike material applied to a finished .say, with little or no bending of the cone.

cone is likely to impair greatly its sound producing ualities. Brittleness in the cone is a desira le characteristic, rovided the paper has at the same time su cienttoughness to withstand commercial transportation and ordinary handling during use.

It has been my experience that paper se eral years old'is better than new stock, presuma-bly because of an increased stiffening of the fibers due to ageing. In anyevent, the paper used for the cone must be capable of being bent without breaking, in order that there may be formed in it the one-or more peri heral creases or bends'on which I rely for ee bodily movement of the diaphragm when in use.

In making the dia hra'gm illustrated a flat sheet of paper is rst cut to form a sector of the required radius and angle. This sector of paper is then creased circumferentially at a lesserradius or radii to mark out the line or linespnwhich the paper may be sharply bent to bring about the results desired by me.

During theprocess of forming the flat sector into a cone those portions of the paper sheet which are to form the supporting brim are pressed one Way or' the other as-the case may be so that they-will assume their proper plane. The cone is then glued along its radial joint. By forming the complete cone this way the brim br circumferential corrugation is formed without any suljgtantial distortion of the paper such asj might cause the main portion of the diaphragm to buckle in spots or become unequally stretched or tensioned.

As an alternative procedure I may cut the sector from the flat sheet of paper and glue it to form a cone, and then by means of a suitable tool crease the cone near its edge and crowd the periphery forward ,until by bending sharply at crease 2 it snaps into the position shown in Fig. 2. Similar circumferential creasing on the lines 2 and- 2" will produce the triple bend or corrugation of Fig. 1. From experience I have found that with a single bend as shown in Fig. 2 the forwardly flaring brim of the cone naturally takes up a position making the same angle to the vertical as does the main body of the cone. I consider this feature of importance because of the freedom from irregular strains in the. cone, and because it contributes to that freedom of bodily movement for the conewhich I have found to be so vital tothe most satisfactory sound production or reproduction.

.By virtue of a circumferential bend or plurality of bends and the rigidity of the paper of which the diaphragm is made, the main portion of the diaphragm is enabled to vibrate substantially as a whole, that is to This results in much more accurate reproduction than-is possible with a diaphragm subjected to bending action. Best results are bad by having a part, but not all, of,

the brim of the cone secured to a supporting structure, the remaining or inner portion of the brim being relied on for flexibility in giving to the cone proper the needed support and restraint, but at the same time allowing it to move axially much as if it were without support. Any arrangement for supporting the diaphra m so that it'is capable of moving bodily with but little restraint may be employed instead of bending or corrugating the peripheral portion of the diaphragm as. above described, but the arrangement shown is inexpensive, is attractive in appearance, and serves its purpose well.

The supportin phragm an electromagnetic actuating mechanism comrises a spun or pressed sheet metal memher 3 of frusto conical sha e having an off set .rim with. a beaded structure for the diage 4 formed as shown to receive the diaphragm. The metal 18 preferably cemented thereto but is enough er than the rim to provide the desired elastic support for the cone. The sheet metal member 3 is provided with a large central opening 5 into which the electrical movement is removably inserted. A post 6, whidh may for t e electrical movement or openings as shown at 10, 11 and 12 for the purpose of facilitating the passage of sound waves from the'inside of the instrument to the-unconfined air. The openings 10, 11 and 1 2 may be of ornamental outline. The electrical movement comprises a U-shaped permanent magnet 13, the two ends of which are slotted as indicated at 14 and 15. To one pole of the permanent magnet there is secured a soft iron pole piece 16. The pole piece 16 is secured to the permanent magnet by means of a screw 17 Threaded studs 18 and 19 constitute poles for the pole piece 16 and are adjustable'therein, toward and away from each other. Between the arms of the pole piece 16 there is inserted a specially formed block 20 of insulating material, such as bakelite, having recesses of proper size to receive the electromagnet coils 21 and 22, each of which surrounds one of the studs.

18 and 19. The central openings through the coils 21 and 22 are of the proper sze to fitthe unthreaded portions of studs 18 and 19. The coils 21 and 22 should be securely gripped within the block 20 and if neces-- sar they may be cemented in lace. The block 20 should make a snug fit lEetween the arms of the -pole piece 16, a d the unthreaded portions of the studs 18 and 19' should fit snugly within the openings through the coils 21 and 22.- A very rigid soft iron armature or reed 23' is firmly bolted at one end to one pole of the ermanent magnet and its free end is normal y situated midway between the ends of the poles formed bystuds 18-"and 19. Normally the polarity of these oles is the same and they are soadjusted that their magnetic attrac- .tions on the armature .are equal and opposing.

A rod 24is rigidly attached at one end to the armature 23 ata point between its -secured end and that part which is disposed between the electromagnet poles. The other endlof rod 24 is attached to the center of the diaphragm by means of set screws 25. Rod 24 forms a connecting link between and functionsto transmit the vibrations of the armature 23 to the diaphragm 1'. In order to provide'a secure attachment to the center of the diaphragm, it isreinforcedbyv means Bf a pair of conical washers 26 secured together, with the-diaphra In between, by

. means of. a hollow rivet 2 through which the rod 24 extends.

Coils 21 and 22 are so wound that current passing one way willcause an attraction of armature 23 toward one of the electroma'gnet ales and vice -'versa. v

The diaphragm actuating mechanism, in-

cluding permanent magnet, armature, con necting link and coils forms a self contained unit which is mounted on a metal plate 28 through the medium of a wooden block 29 to which the permanent magnet is secured by means of a three-armed clamping plate 30, which: embraces the permanent magnet, and a pair or wood screws 31. Plate 28 is secured to the sheet metal supporting member 3 by means of four machine screws 32. A lifting handle 33 is attached to plate 28 and affords a convenient means for carrying the instrument about. c

Although I do not wish to be limited by any. thcor for the highly satisfactory results obtained by me in sound reproduction through use of the apparatus above described as a loud speaker on radio and line wire circuits, nevertheless, I.record my present ideas on the subject. The armature 23 beingof metal and relatively thick and stiff has a natural vibratory period above audibility. The magnetic flux from that pole of the permanent magnet to which the armature is rigidly attached streams across the armature toward the other pole of the per manent magnet, and at or near the free or vibratory end of this armature that flux is split into two parts, one part going through soft pole 18 to the soft iron poleishoe 16, and thence to the permanent ma'gnet. and the other part going throughthepole 19. Poles 18 and 19 are adjustable, and-by longitudinal movement can. be so] positioned that themagnetio fiux is ndrmallynsplit into two equal portions. This adjustment can be made at the factory and-the poles can be 5 permanently clamped in their adjusted position by suitable transverse bolts passing through the slotted pole shoe.

A current impulse through the speech coils 21 and 22 redistributesthe magnetic flux which streams outjof armature 23 into the'adjustable poles 18 and 19 so that more than half of it goes to one pole, say pole 18.

,The armature 23 then moves toward pole 18 and by its movement decreases the air I gap thereby increasing the vflux to that 'suflicient to. permit fiexingof it, but the armature is so stiff and-is so supported vat one end that ,it cannot strike the adjustable pole toward which 'it moves. A current impulse through the-speech coils in the opposite direction will produce '-a flexing of the armature toward pole 19," andv the swinging armature is thus made to take up movements which infrequency and in vmagnitude represent the current variations the structure in the speech coils. Bar 24 is rigidly attached to armature 23 between the vibratory end and the supported end of that arma, ture. This I regard as an important innovation. There is a "gain in power but a loss in the magnitude of movement.

The exact point at which bar 24 can best be attached to armature 23 lies about mid- 'way of the length of the armature, and

depends somewhat on the thickness and stiffness of the armature, and on the weight and other characteristics of the diaphram to which bar 24 is ri idly attached. The point can best be foun by trial.

The dia hragm which can best be used with this e ectrical movementis of the conical t pe, and preferably not less than 9" in iameter. The fibrous material of which the cone is made should be light in weight and relatively stiff. A porous pa er, the individual fibers of which are tig tly interlocked with one another and have been rendered stifi bfy sizing or ageing, will serve well. Sti ness or brittleness ac uired by filling the interstices between t e fibers of the paper, as with varnish, does not help. Free suspension of the cone so that it may move as :a whole the coneasa whole that freedom of bodily movement that I have found so hi hly desirable, while at the same time In ing rugged enough'for merchantability.

By thus coordinating the diaphragm to the electrical movement a highly satisfactory loud speaker can be obtained. Its tonal characteristics can be varied some- I what. by changing the. weight or stiifness of the vibratory armature or reed, or by chan 'ngthe weight, size or thickness of the brous cone. For best speech repro: duction the treble shouldf-be emphasized,

' and for best reproduction'of'music the base tones should be emphasized. As to the lower tones of themusical scale, my loud speaker presents great advantage over any structure within my observation where movement of a small flatdiaphragm of the telephone type is amplified through a horn. My loud speaker is entirely free from the unpleasant or horny-xtimbre of loudspeakers of the-horn type.

This invention is capableof considerable variation and modification 'and'should not 1 beconstrued aslimited to the particular 1 of said armature.

ments of said armature.

1. In a translating device, the combina- I tion of a permanent magnet, a resilient reed supported at one .end by net and polarized thereby, two poles of a speech magnet on opposite sides of the free end of said resilient reed and between which the endof said reed projects,- and means for translating into sound the vibratory movements of said reed.

2.-In a translating'device, the combination of a permanent magnet, a resilient reed rigidly attached at one end to a poleof said magnet and polarized thereby, two poles of aspeech magnet on opposite sides of the central plane of said ermanent magnet and between which the dice end of said resilient reed projects, and means for translating into sound the vibratory m'ovementsof said reed. L

3. In a translating device, the combination of a U-shaped permanent magnet, a resilient polarized vibratory armature supported at one end on a pole of said magnet and polarized thereby, a bifurcated pole shoe embracing the other end of said armature and between the two poles of which the end of said armature projects, a speech winding 1n magnetizing relation to said pole shoe and with'its axis perpendicular to the plane of said ma et, and means for translating into soun the vibratory movements 4. In a translating device, the combination of a permanent magnet, a polarized vibratory reed suplported thereon at one end and through whic the magnetic flux of said magnet passes longitudinally,v a bifurcated pole shoe embracing-the other end of said armature and betweenthe two poles of which the end of said armature-projects, a speech winding on each sideof the free end ot said reed and in magnetizing relation to said nole shoe, and aconical diaphragm opperatively connected to said armature to a pole of said mag-- translate into sound the vibratory move- ,5. In a translating device the combinetign of .a magnet, 11 vlbratory armature supported at one end by a and polarized thereby, a ifurcated pole shoe embracing the other end of said armature and betweenlthe two poles of which the end of said armature projects, a speech winding in magnetizing relation to said pole shoe, and atransmission. rod extending at right angles to the plane of said ma et andconnected to said-armature interme 'ate its ends and substantially perpendicular thereto.

6. In a translating device the combination of a permanent magnet, a polarized vibrale of said 'magnet' tor-y reed rigidly' supported at one end by a pole of'said magnet, a bifurcated pole shoe embracing the other end of said reed and vibratory reed rigidly supported'at one end between the two poles of which the end of said reed projects, a speech winding in magnetizing relation to each bifurcation of each pole shoe, and means for translating into sound the vibratory movements of said reed.

' 7. In a translating device the combination of a permanent magnet, a polarized by-a pole of said magnet and polarized thereby, a bifurcated pole shoe embracing the other end of-said reed and between the two poles of which the end of said reed projects, a'speech winding in magnetizing relation toeach bifurcation of said ole shoe, a transmission rod extending at right angles to the plane of said magnet, and a. diaphragm connected to said rod and having its periphery positioned in a plane parallel to that of said permanent'magnet.

8. In a translatin device the combina tion-of a magnet, a vibratory reed supported at one end by one pole ofsaid magnet and through which the magnetic flux of said magnet passes longitudinally, a pole shoe for the other poleofsaid magnet, said shoe having two poles on opposite sides of the free end of saidreed and between which said free end projects, a speech-coil ,for'each shoe,po1e-, and.means for translating into sound the movements of said a'rmaturepro ducedby-said speech coils; I y

9. In a translating device, the combina: tion of a magnet, a vibratory reed rigidly supported at one .end by one pole of said magnet, a'pole shoe 'for the other pole of said magnet, said shoe'having two poles on opposite, sides of the central plane of said magnet and between which thelfree end of said armature projects, a s eech coil' for other pole 0 said magnet, said? shoe having each pole shoe, and means or translating intosound the moy ements of said armature produced by-said speech coils.

10. In a translating devicethe combination of a permanent magnet, a vibratory reed rigidl a softiron pole shoe forthe other'pole of two'opposed soft iron poles on opposite si es of the free end of said armature and between 'which' said end projects, a speech coil for each shoe,

and means for, translating into sound the movements-of sald armature produced by said speech coils.

11-. In a translating device the combination ofv a (permanent magnet,a flexible arma-' 6o ture ri yattached atone end to one pole of sai magnet-said armature being, polars ized thereb'y a soft iron pole shoe .for the gaid magnet, said shoe'having supported at one end by one pole of sai magnet and polarized thereby,

two opposed soft iron poles on opposite sides of thefree end of said armature and between which said end projects, a speech COll for each pole shoe and through which the magnetic flux of said polarized armature may divide, and means for translating into sound the movements of said armature produced by said speech coils.

12. In a translating device the combination of a permanent magnet, a. flexible armature rigidly attached at one end to one pole of said magnet,. a soft iron pole shoe for, the other pole of said magnet, said shoe having two opposed adjustable poles on opposlte sides of-the free end of saidarmature said magnet, said shoe having two opposed adjustable poles on opposite sides of the free 'end' of said armature'and between which said free [end projects, afispeech coil encircling each shoe pole, and means, including a diaphragm, for translating'i'nto sound the movements of said armature'produced by said s ech coils.

14. na translating reed rigidly supported at one en a pole shoe adjacent the other end of said reed, 'said shoehavin two poles on opposite sides of the free" en of said reed and between which that free end projects, and a speech coil for each pole shoe, each 'of said coils being held in stationary osition with respect to the pole'shoe an each .pole being axially rotatable in. the pole shoe andlongidevice the combina-' t on of a permanent magnet, a olarized tudinally adjustable through itsspeech coil.

15. In a translating device,'-the combination of .a U-shaped permanent magnet, ,a polarized reed rigidly secured at one-end to end of said ree on opposite sides of the free end of said mod and between which that'free end rojects, .anda speech coil for each pole s oe,

each'of .said coils being'held in stationary position with; respect" tothe pole shoe, and

each pole being axiallly rotat 1e inthe pole shoe and lon itudina ly adjlistable through its speech 00' ture.

' i i MARCUS duos-Kins In testimony whereof I ailix my signs a pole of said magnet and olarized thereby, a soft ironpole shoe ad acent the other said shoe having two poles

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