US 2392143 A
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Description (OCR text may contain errors)
Jan. 1, 1946. GRAHAM v 2,392,143
- LOUDSPEAKER 1 Filed Nov. 30, 1942 Zmventor Patented Jan. 1, 1946 UNITED STATE noun-SPEAKER Maxim L. Graham, Indianapolis, Ind., assignor to Radio Corporation of America; a corporation of Delaware Application November 30, 1942, Serial No. 467,469
This invention relates to loudspeakers of the dynamic type, and more particularl to the diaphragm and voice coil assembly thereof,
Loudspeakers of this typehsually include a magnetic structure formed with an air gap in which is located a flange or skirt secured to the diaphragm and upon which the voice coil is wound. One of the disadvantages of conventional constructions is that, unless the voice coil is properly, centered in the air gap, it frequently rubs against the pole pieces of the magnetic structure during vibration of the diaphragm, and this usually results in short-circuiting of the turns of the coil. Under certain conditions, it is also desirable that the voice coil be protected from exposure to the atmosphere. For example, in loudspeakers used on board ships, the voice coils frequently are attacked by the sea air and they are rendered unsuitable for use.
The primary object of my present invention is to provide an improved loudspeaker which will not be subject to the aforementioned disadvantages.
More particularly, it is an object of my present invention to provide an improved loudspeaker of the type set forth wherein the voice coil is so mounted that it will not only be protected from the atmosphere, but will also be protected from contacting the pole pieces during vibration of the diaphragm.
Another object of my present invention is to provide, in a loudspeaker as aforesaid, an improved diaphragm and voice coil assembly.
Still another object of my present invention is to provide, in a diaphragm for dynamic loudspeakers, an improved mechanical connection between the diaphragm and the voice coil.
It is also an object of my present invention to provide an improved loudspeaker as aforesaid which is simple in construction, inexpensive in cost. and highly efllcient in use.
In accordance with this invention, the diaphragm may comprise a central, vibratile portlon having 2. depending flange, and a peripheral suspension also having a depending flange, the two flanges being concentric'and spaced slightly from each other to provide a channel within which the voice coil is disposed. The voice coil may be secured to the diaphragm by cement or in any other suitable manner to protect it from the atmdsphere. when the diaphragm is mounted in place, the flanges are disposed in the air flanges may all be molded out of suitable material in one piece. According to another form of the invention, the vibratile portion together with its flange may be molded together to constitute one unitary member, the suspension and its flange may be molded together to constitute a secondary unitary member, and the ends of the two flanges may be cemented or otherwise suitably secured to each other to provide one integral structure.
The. novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention it-- self, however, both -as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description of two embodiments thereof, when read in connection with the accompanying drawing, in which Figure l is a fragmentary, central, sectional view of a dynamic loudspeaker having a diaphragm and voice coil assembly according to one form of my invention, and
Figure 2 is a similar view showing a modified form of diaphragm and voice coil assembly formed in accordance with the present invention.
Referring more particularly to the drawing, wherein similar reference characters designate corresponding parts throughout, there is shown a diaphragm having a central, vibratory portion l formed with a depending annular flange 3 extending in the axial direction. The diaphragm is supported by a peripheral suspension 5 which may be formed with one or more corrugations 'l in well known manner and which is provided with a downwardly extending flange 9. The flanges l and 9 are concentric and are spaced slightl from each other to provide a channel or groove ll therebetween in which a voice coil i3 is mounted, the flanges 3 and 8 being connected at their lower ends. The diaphragm I, the suspension -5, and the flanges 3 and 9, together with their connecting portion, may be molded as one unitary, integral structure out of paper, synthetic resin, or the like, or it may be pressed out of thin sheet metal, or any other suitable material. The voice coil may be wound separately and then cemented into the channel II with cement or the like 2| which completely covers it. If desired, the voice coil it may be secured to the diaphragm with the aid of a resinous cement by heating or baking whereby the diaphragm and voice coil assembly gap and protect the voice coil from the polepieces. According to this form of my invention, the vibratile portion, the suspension is made into one, integral structure.
The diaphragm may be supported for vibraand the tory movement in well known manner at the suspension I. the flanges 3 and I extending into the air gap ll of a suitable magnetic structure comprising an inner pole piece I! and an outer, annular pole piece is, as is well known in'the prior art.' It will be noted that the voice coil is is sandwiched in between the flanges 3 and 8 which protect it from contact with the pole pieces I! and is. At the same time, the cement or the like 2| which surrounds the voice coil l3 and which serves to connect it to the diaphragm protects the voice coil from attack by the atmosphere or other foreign matter.
In some cases, it may be desirable to make the diaphragm and the suspension of two separate units as shown in Fig. 2. In this modification, the diaphragm I and its flange 3 are made as one unitary member separate from the suspension I and its flange 8 which constitute a second unitary member. The flange .8 may be formed at its lower end with an outwardly extending oflset portion 23, and the flange 9 is made at its lower end with an inwardly extending oflset portion 25 which overlaps the portion 28. The flanges 3 and 9 are secured to each other at their lower ends in concentric but slightly spaced relation with each other to provide the channel Ii therebetween, as in the modification of Fig. 1. In assembling this form of diaphragm and voice coil, the voice coil is first wound on the outside of the flange 3 and is secured thereto by a suitable cement or the like. The suspension is then applied to the assembled portion l and the voice coil I3 whereby the coil It becomes confined between the two flanges 3 and 9. The entire assembly may then be baked to provide a substantially integral unit.
AlthoughI have shown and described but two embodiments of my invention, it will be apparent to those skilled in the art that many other modiflcations thereof, as 'well as changes in the ones described, are possible within the scope of my invention. I therefore desire that this invention between said vibratile portion and said suspension and constituting a connection therebetween, and a voice coil secured to said diaphragm within said channel.
2. In a loudspeaker, an acoustic diaphragm comprising a central, vibratile portion and a peripheral suspension therefor, said vibratile portion and said suspension each including an annular flange, said flanges being disposed in spaced shall not be limited except insofar as is made necessary by the prior art and by the spirit of the appended claims.
I claim as my invention: 1. In a loudspeaker, an acoustic diaphragm comprising a central, vibratile portion and a peripheral suspension therefor spaced radially from said vibratile portion, means providing a channel relation to each other and being connected at their ends whereby to provide a. channel therebetween, and a voice coil secured to said diaphragm within said channel.
3. In a loudspeaker, an acoustic diaphragm comprising a central, vibratile portion and a peripheral suspension therefor, said vibratile portion and said suspension each including an annular flange, said flanges being disposed in closely spaced, concentric relation and being connected at their ends whereby to provide a narrow, annular channel therebetween, and a voice coil secured to said diaphragm within said channel.
4. The invention set forth in claim 3 characterized in that said vibratile portion, said suspension and their respective flanges are all formed of one unitary member.
5. The invention set forth in claim 3 characterized in that said vibratile portion and its flange are formed of one unitary member, characterized further in that said suspension and its flange are formed of another unitary member, and charterized still further in that said members are united'into one integral structure. I
6. The invention set forth in claim 3 characterized in that said flanges are formed with offset portions at their ends, and characterized further in that said flanges are connected to each other at said offset portions.
7. In a loudspeaker, an acoustic diaphragm comprising a central, vibratile portion including an annular flange thereon extending in an axial direction and a peripheral suspension concentric therewith and also including an annular flange, said last named flange being concentric with and spaced slightly from said first named flange and said flanges being connected to each other at their ends whereby to provide a narrow, annular channel therebetween, and a voice coil secured to said diaphragm within said channel.
MAXIM L. GRAHAM.