CA1123506A - Adjustable dual spider for a loudspeaker - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The present invention is an internal stabilizing spider-dust cap for use in combination with a loudspeaker that has an external centering spider and a surround mechan-ically coupling the conically shaped diaphragm of the loudspeaker to the frame thereof. The loudspeaker includes a ring-shaped magnet, a pole piece, gap plate, and a pole plate of iron which are separated by a cylindrical voice coil member and a voice coil, which is disposed about the voice coil member, and which provides a magnetic gap for the voice coil. The centering spider aligns the voice coil within the magnetic gap.
The stabilizing spider is mechanically coupled to the internal sidewall of the conically shaped diaphragm and to a rod which is disposed perpendicularly into the pole piece. The center of the stabilizing spider is mechanically clamped to the rod by a mounting device which is secured in place by a set screw in one embodiment so that it may be raised and lowered in order to modify bias compliance linearity of the existing suspension.
A lateral adjustment may also be provided to increase effective excursion and to correct for faulty assembly.

Description

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_ BACKGROUND OF THE INVENTION

2 Field o~ the Invention . . .

3 The presen-t invention relates to loudspeakers and

4 more particularly to dual spider arrangements for use in combina~ion with the loudspeakers.
6 Descri~tion of the Prior Art 7 U. S. Patent No. 2,812,825, entitled Loud Speaker 8 Diaphragm Supporting Member, issued Charles L. Matthews on 9 November 12, 1957, teaches a m~mber for supporting a moving coil in an electro-acoustical transducer and for 11 centering suc~ coil in an air gap in such transducer. The 12 member includes a corrugated disc of resin-impreg~ated, 13 thin, resilient, porous cotton ~abric and an external film 14 of modi~ied po~yv1nyl chloride type resin on ~he surface o~
~e disc-to fill the pores in the cotton.
16 U~ S. Patent No. 2,641,329, entitled Loudspeaker 17 Diaphragm with Trznsversely Arched Sti~fener Means, issued 18 to Sidney E~ Levy-and Abraham B. Cohen on June 9, 1953 19 teaches an acoustic diaphragm for loudspeakers, that ~
an acoustical energy-responsive diaphragm member of 9ubstan-21 tially conical ~orm having a relatively rigid transversely 22 arched stiffener member secured at its ou~er marginal edge 23 to an intenmediate por~ion of the diaphragm mQmber and 24 extending across the latterO The stifener member has a ~5 plurality of rela~ively small sound-radiating per~orations 26 therethrough, the per~orations of t~e stiffener member 27 being spaced from each other and each perforation ~8 having its axis inclined at an angle t~ the central axis ~aS
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_.. ~,_ , 3~i of the diaphragm member. The perorated sti~fener memb~r 2 has the property of directional control o~ high freguency 3 propagation generated from the center of the diaphragm 4 member.
U. S. Patent No. 3~905,448, entitled Loudspeaker, 6 issued to Hirotake Kawakami, Toshio Sasabe, Toshio Hirosawa, 7 Nobuyaki Arakawa, Kozo Kok~lbu, Kazumasa Abe and Toshiko 8 Harashino, on September 16, 1975 teaches a loudspeaker with 9 a suspension device for supporting the diaphragm from its rame. In the loudspeaker, ~he upper part and the lower part 11 of a oone~shaped diaphragm with a voic~ coil ax~ suspended 12 ~rom a frame by a ring-shaped suspension member, herein 13 referred to as a first suspension means, and by ~ ring-shaped 14 suspension member, hexein referred to as a suspension means, respectively. At least one o~ the suspension means is formed 16 of a mixture-o~ elas~ic material such. as rubber, with carbon 17 fibers therei~. The fibers are needle-like and are aligned 18 radially in the material of at least one of the suspension 19 means.
U. S. Patent No. ~,767,004, entitled loudspeaker, 21 issu~d to Arthur Liebscher on October 23, 1973, teaches ~2 a loudspeakex that is provided in which a thin surround 23 is employed ~or the speaker cone o impervious foam material, 24 the surround being characterized by omni-directional elastic tension and ~eing secured between the cone and the support.
26 The loudspeaker also has a pair o:E spaced coaxial 27 supports which support the coil~ The.supports have radial 28 rigidity and high axial flexibility so that the surround ___ , ," ,_ ,_ _,,, .,_,,~.. , .. .... ~_ .. ".. , . ... ~ ... ___. _. ,_ _,. .____.. ...... ~ _ ... , ,.. ... ,.. , . _, .. .. .... .....
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serves no supporting function and acts prim~rily as an air 2 separator at the periphery of the diaphragm.
3 Abraham B. Cohen has written an article entitled, 4 The Mechanics o~ Good Loudspeaker Design, published in Volume 2, Number 3, July, 1954, Journal of the Audio 6 Engineering Society on pages 176 to 1~2. In his article 7 he discusses a double spider to correct voice coil mis-8 aligr~ment as follows:
9 "~aving thus dealt brie~ly with one of the unrecog-nized causes of gap and voice coil misallgnment, we must 11 complete the study of the problem by considering the more 12 commonly recognized cause o such misalignment. Damaging 13 eccentric and rocking motion o the voice coil about its 14 axis of motio~ will occur while it iS vibrati~g, if the means used to maintain accuracy o~ such motion are inade~uate 16 to meet the mechanical re~uirements i.mposed on the 1? system by the laxge power ou~put expe!ctea of it. The 18 usual means lor preventiny such side swaying of the voice 19 coil motion ~s-khe well known spider located directly at the voice coil area. There is a new and exceedingly 21 successful 501utio~ to the problem of maintaining preclsion 22 voice coil alignment during vibration. Placement o~ two 23 axially spaced spiders at the apex area of the vibrating 24 system provides a dual guLde to the vibrating system that keeps the voice coil motion rigidly channeled along one 26 line of vibration ~hat neither deviates in an~ular direction 27 from th~.central axis nor becomes eccentrically located 28 in respect to this axis."

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1 In his book, Hi-Fi Loudspeakers and nclosures, -2 2nd Edition, Abraham Bo Cohen further describes a dual 3 spider arrangement on pages 87 to 88 in which he states:
4 "The mechanical precision with which the suspension holds the whole assembly together determines the mechanical 6 longevity o~ the voice coil itselfO The voice coil must be 7 kept per~ectly aligned mechanically in its magnetic gap at 8 all ~imes during its vibration cycle. If, during its 9 vibration, it sways or twists sideways, it may scrape itself against the walls of the gap, causing rubbing of 11 the voice coil, which in turn results in distortion, 12 in shorted turns, and sooner or later, in a~ open voi~e 13 coil. Althoug~ the spider is norc~mlly the device that 14 keeps the coil centered in the gap when no motion is involved it is the combination of the spider cmd the other cone 16 suspension that dictates how the cDil behaves in the gap 17 under mo~ion~ Obviously, even though the spide.r may ~eep 18 the coil cente~ed, if the cona tilts, it will tilt the 19 coil and cause rubbing. Where small motions are involved, as in tweeters, t~is condition does not present a 21 pxoblem. ~owever, in the case o~ woo~ers, where voice 22 coil motions of t~e order of 3/8 inch or more are prevalent, 23 added insurance against voice coil misalignment may be had 24 by the double spider suspen~ion. The addition of ~he second stabil;zing spider part way up ~he cone o~ the 26 speaker acts as a second guide to the linear in and out motion 27 of the voice coil, keeping the voice coil not only rigidly 28 centered, but also moving in a rigidly prescribed axis."

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1 "In loudspeakers in which the voice coil travels a 2 straight and narrow path, and in which the side play of the 3 coil is rigidly controlled, the clearances betw~en the 4 overall gap walls and the voice coil may be reduced, with resultant improved magnetic circuit e~flciency, because 6 of the reduced gap cross-section. Thus we see again that 7 the final acoustic performance of the loudspeaker is a 8 function of the mechanical toleranc s permissible between 9 co~trolled moving parts."
There have been several other loudspeakexs that 11 have incorporated dual spiders for supporting their 12 ~iaphragmsO Th.e di~iculty with these dual spiders is 13 tha~ their m~nufacturer is unable to adjust the linearity 14 of the loudspeakers' response after manu~ac~ure thereo~.
The two exter~ally placed spiders are disposed in a fi~ed 16 position. It would be ~deal to provi.de an adjustable 17 spider for loudspeakers that can reduce the bias in the 18 response ~hereor.
19 SUMMARY OF T~E I~VENTION
In view of the foxegoi~g factors and conditions 21 characteristic of the prior art~ it is a primary objec~
22 of the present invention to provide an adjustable internal 23 ~pider ~or use in combination with a loudspeakex having 24 an ~xtexnal spider me~hanically coupling its frame to th~
base of its diaphra~m.
26 It is another object of the present invention 27 to provide a dual spider arrangement that not only eliminates 28 lateral movement, but also provides more truly axial or _, _ _, _ , ,, _, "__,_,_.. ,~ .. , ._ , .. , ,__ . ____ .. ,. .. ___ ._ , . ..... _ .. _, . , .. ... .. , ~ . .... ... _... . ....
.... ....

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linear movement by having a larger lateral separation 2 between the dual spiders.
3 It is still another object of the present invention 4 to provide an internal spider that functions as a dust cap thereby reduciny the number of components re~uired in the 6 loudspeaker.
7 It is yet skill another object o~ the present ~ invention to provide a clamp system that allows lateral 9 spider adjustment in order to correct a faulty assembly that is incapable o~ true axial motion withouk remanu~acturing.
11 In accordance with an embodiment of the present.
12 invention, an internal stabilizing spider-dusk cap for use 13 in combination wi~h a louaspeaker that has an external 14 .centering spider and a surround mechanically coupling the conically shape-~ diaphragm of the loudspeaker to the frame 16 thereof has b~en described~ The loudspeaker includes a pole 17 piecej a gap plate, a pole plate of :Lron and a ring-shaped 18 magnet which are separated hy a cylindrical voice coil 19 msmber and a voice coil, which is disposea about the voice coil member, an~ which provides a magnetic gap for the voice 21 coil. The centering spider aligns the voice coil within 22 the magnetic gap~ The stabilizing spider is mechanically 2~ coupled to th~ internal sidewall of ~he conically shaped 24 diaphragm and to a rod which is disposed perpendicularly into the pole piece. The center of the s~abilizing spider is 26 mechanically clampe~ to the rod by a mounting plate de~ice 27 which is secured in place by a set screw in one embodimenk so 28 .that ik may be ra.ised and lowered in order to modify the 3~

1 compliance linearity of the existing suspension. A lateral 2 adjustment may also be provided to increase e~fective 3 excursion and to correct for faulty assembly.
4 The featur~s of the present invention which are believed to be novel are set forth with particularity in 6 the appended claims.
7 Other objec~s and many of the attendant advantages 8 will be more readily appreciated as the same becomes better 9 unders~ood by reference to the following detailed description and consid~red in connection with the accompanying drawing 11 ~n which like reerence symbols designate like par~s through-12 out the ~i~ures.

14 FIG. 1 is a perspective view of a first loudspeaker having a dual spider which has been constructed in accordance 16 w.ith the principles o the present invention.
17 FIG. 2 is a side elevatio~al view of the loudspeaker 18 of FIG. 1 19 FIG.- 3 is a side cross-sectional view of the loudspeaker of FIG. 1 t~ken along line 3-3 of ~IG. 2.
21 FIG. 4 is a partial top plan view of the loudspeaker 22 o~ FIG. 1.
23 FIG. 5 is a partial ~o~tom plan view of the loudspeaker 24 of FIG. 1.
FIG. 6 i~ a cross-sectional side view of a ~irst 26 clamping apparatus for an internal stabilizing spider for the 27 loudspeaker of FIG. 1.
28 FIG. 7 is a cross-sectional side view o a second -~8-_, _ .... , .. ..... .. _ _ _ _ 1 clamping apparatus for an internal stabilizing spider ~or 2 the loudspeaker of FIG. 1.
3 FIG. 8 is a side cross-sectional view o~.a second 4 loudspeaker having a dual spider which has been constructed in accordance with the principles of the present invention.
6 FIGu 9 is a side cross~sectional view o the loudspeaker 7 having a dual spider which has been constructed in accordance 8 with the principles of the present invention.
9 DESCRIPTION OF TME PRE~ERRED EMBODIMENT
The present invention can best be understood by 11 reference ~o a descrip~ion of its preferred embodIment and 12 to the showings in the drawing. The invention is an 13 improvement for use in combination with a loudspeaker 10 14 shown in FIG. I to provide an adjl7stable stabilizing spider 11. The loudspeaker 10 includes a conically shaped diaphragm 16 12 having a front peripneral edge 13, an external sidewall 17 14, an internal sidewal~ 15 and a has~ peripheral edge 16 18 and a frame 17 ha~ing a conically shaped portior~. adapted 19 to receive-the diaphragm 12 and a front plate ~J The 2G loudspeaker 10 also include~ a surraund 19 which mec~anically 21 couples ~h~ f7 ont peripheral edge 13 of the diaphragm 12 to 22 the frame 17.
23 Re~rring now to FIG. 2 the loudspea~er 10 further 24 includes a cylindxically shaped voice coil member 20 which is mecha~ically coupled to the base peripheral edge 1~ of 26 ~he diaphragm 12, a voice coi~ Zl disposed about the voice 27 coil member ~0, a:.ring shaped magnet 22, which is disposed 28 about the voice coil 21 and which is mechanically coupled _.. _ ., ... ,., . , . .. ., _,.. , ,". _ -- .. , ___ ., ., _, __. .,, ~ _ .,.. _, . . .. _.. , .. , . ,. ,.. _ .. ..........
...... .. .. .... .. .

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1 to the back pla-te 18, and a cylindrical iron pole piece 23 which is disposed within the voice coil member 20 and which is also mechanically coupled to the back plate 18. The ring-shaped may-net 22 and the pole piece 23 create a magnetic gap across the voice coil 21.
Still referring to FIG. 2 the loudspeaker 10 still further includes a centering spider 24 which mechanically couples the base peripheral edge 16 of the diaphragm 12 to the base por-tion 26 of the frame 17. The centering spider 24 centers the 1~ voice coil 21 within-the magnetic gap.
Referring now to FIG. 3 in conjunction with FIG~ 4 the stabilizing spider 11 is mechanically coupled to the internal sidewall 15 of the di~phragm 12 ~o a rod 25 which is disposed perpendicularly to the pole piece 23 at th.e center thereof.
Referring briefly to FI~. 5 one may view a front plate 18 of the loudspeaker 10.
Referring again to ~IG. 3 the sta~iliæing spider 11 is mechanically coupled to the rod 25 by a mounting device 30 which is adapted to travel up and down the rod 25 and which is secured in place by a set screw 31 to provide adjustability to the stab-ilizing ~Pider. In operation the stabilizing spider 11 provides a more truly axial movement while eliminating lateral movement than the dual spider taught by Abraham B.. Cohen .in his articles.
The stahilizing spider 11 also functions as a dust cap.
Referring no~ to FIG. 6 a first coupling device 60 for mechanically coupling the ~tabilizing spider 11 to the 3~

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1 rod 25 includes a pair of disc-shaped members 61 between which 2 the stabilizing spider 11 is placed and which are joined by a 3 pair of set screws 62. The stabilizing spider 11 may be 4 radially adjusted. The coupling device 60 may be adapted for traveling slideably along the rod 25 so that the stabilizing 6 spider 11 may be axially adjusted and is then secured by a 7 third set screw 63.
8 Referring now to FIG. 7 a second coupling device 70 9 for mechanically coupling the stabilizing spider 11 to a rod `B 10 71 o~ a seeon~ type having a threaded portion 72~ The second 11 coupling device includes a top piece 73 and a bottom piece -~
12 which the stabilizing spider 11 i~ placed. The second 13 coupling device 70 i.s adaptad to be mechanically coupled to 14 the threaded portion 72 of the rod 71 so that the stabili2ing spider 11 may be adjusted axially along the rod 71.
16 Referri~g now to ~IG. 8 the stabilizing spider 11 may 17 be mechanicall~ coupled to a rod 81 whlch is secured to a 18 support mem~er 82 which is at~ached t:o oppositely disposed 19 peripheral edges o the ~rame 17 o~ the loudspeaker 10. The stabilizing spider 11 i5 mechanically coupled ~o the rod 81 21 by the second coupling device 70.
22 Referring now to FIG. 9 the stabilizing spider 11 23 may be mechanically coupled to a mass 90 which has a central 24 hole 91 therein and slideably coupled to the rod 25 so that the stabilizing spider 11 is axially aligned and centered.
26 The mass 90 provides additional mass which may be adjusted 27 in addition to the compliance of the stabilizing spi~er 11 28 in order to alter the mechanical-acoustical sys~em of the .
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1 loudspeaker 10. There is also a cylindrical~Teflo~ bearing 2 92 to provide slideability for the mass 90 disposed within 3 the hole 91 thereof.
4 Furthermore, it should be noted that the schematics of the device have not been drawn to scale and that distances 6 of and between the figures are not to be considered signifi-7 cant.
8 Accordingly, it is intended that the foregoing 9 disclosure and showings made in the drawing shall be considered as illustrations of the principles of the present inventi~n~

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Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A stabilizing spider arrangement for use in combination with a loudspeaker that includes:
a. a conically shaped diaphragm having a front peripheral edge, an external sidewall, an internal sidewall and a base peripheral edge;
b. a cylindrically shaped voice coil member which is mechanically coupled to the diaphragm adjacent to its base peripheral edge;
c. a voice coil mechanically coupled to the voice coil member;
d. a ring-shaped magnet disposed about the voice coil member;
e. a pole piece disposed within the voice coil member with the ring-shaped magnet and the pole piece creating a magnetic gap therebetween;
f. a frame that includes a conically shaped portion with an internal sidewall which receives the conically shaped diaphragm and a base portion which receives the ring shaped magnet, the voice coil member and the pole piece; and g. a centering spider which mechanically couples the base portion of the frame to the base peripheral edge of the diaphragm;
said stabilizing spider arrangement comprising:
h. a rod which is mechanically coupled to the pole and which is disposed perpendicularly thereto at its center;
i. a stabilizing spider which mechanically couples the internal sidewall of the diaphragm to said rod;
j. a coupling device which has a top member, which has a cylindrical collar coupled in axial alignment there-with, and a bottom member between which said stabilizing spider is placed;
1. Claim 1 continued....
   
   k. a pair of set screws mechanically coupling said top member and said bottom member together with said stabilizing spider being disposed therebetween so that said stabilizing spider may be radially centered; and 1. a third set screw which secures said collar of said top member so that said top member and said bottom member may be secured in place along the axis of said rod by said third set screw.
   
   2. A stabilizing spider arrangement for use in combination with a. a conically shaped diaphragm having a front peripheral edge, an external sidewall, an internal sidewall and a base peripheral edge;
   b. a cylindrically shaped voice coil member which is mechanically coupled to the diaphragm adjacent to its peripheral edge;
   c. a voice coil which is mechanically coupled to the voice coil member;
   d. a ring-shaped magnet which is disposed about the voice coil member;
   e. a pole piece which is disposed within the voice coil member with the ring-shaped magnet and the pole piece creating a magnetic gap therebetween;
   f. a frame that includes a conically shaped portion with an internal sidewall which receives the conically-shaped diaphragm and a base portion which receives the ring-shaped magnet, the voice coil member and the pole piece; and g. a centering spider which mechanically couples the base portion of the frame to the base peripheral edge of the diaphragm;
2. Claim 2 continued....
   
   said stabilizing spider arrangement comprising:
   h. a stabilizing spider which is mechanically coupled to the internal sidewall of the diaphragm;
   i. a mass which is mechanically coupled to said stabilizing spider at its center;
   j. a rod which is mechanically coupled to the pole piece and which is disposed perpendicularly thereto at its center; and k. a cylindrical bearing which may be inserted into a hole in said mass so that said mass may slidably engage said rod in order to provide an axial centering of said stabilizing spider arrangement.